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  • 1.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Thessaly, Greece.
    Hosseinpourpia, Reza
    Georg-August-University Göttingen, Germany.
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Tensile strength of handsheets prepared with macerated fibres from solid wood modified with cross-linking agents2015In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, no 8, p. 959-966Article in journal (Refereed)
    Abstract [en]

    This study was conducted to explain the tensile strength loss of wood due to the modification with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and glutaraldehyde (GA). Modified and control wood blocks were macerated to deliberate fibres, and handsheets were produced thereof. The nitrogen content of the fibres indicated that maceration removed the major proportions of DMDHEU. The stability of GA in wood during maceration was not assessed. Tensile strength determined at zero span (z-strength) and finite span (f-strength) was equal for the handsheets from DMDHEU-modified fibres and the control handsheets. The microscopic appearance of the tested finite-span paper strips from DMDHEU-modified fibres mainly indicated interfibre failure and did not differ from the fibre fracture mode of the control handsheets. In contrast, the z-strength of the handsheets from GA-modified fibres was lower than that of controls and decreased with increasing content of GA in the initial modified wood. The f-strength behaviour of the handsheets from GA-modified fibres was the opposite: it was higher than that of controls and increased with increasing GA content. The microscopic appearance of the rapture zones of the finite-span testing mainly indicated intrafibre failure for the GA-modified fibres. It was concluded that cross-linking is likely to be the major reason for tensile strength loss of GA- and DMDHEU-modified wood. In terms of DMDHEU-modified wood, the incrustation of the cell wall by the resin and the reduction in pliability could play an additional role.

  • 2.
    Altgen, Michael
    et al.
    Aalto Univ, Finland.
    Willems, Wim
    FirmoLin Technol BV, Netherlands.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Rautkari, Lauri
    Aalto Univ, Finland.
    Hydroxyl accessibility and dimensional changes of Scots pine sapwood affected by alterations in the cell wall ultrastructure during heattreatment2018In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 152, p. 244-252Article in journal (Refereed)
    Abstract [en]

    There is a complex link between the water sorption behavior and the presence of accessible hydroxyl groups in the wood cell wall, which can be altered by heat-treatment (HT). This study analyses the effect of changes in the cell wall ultrastructure caused by two HT techniques on the hydroxyl accessibility, water vapor sorption and dimensional changes of Scots pine (Pinus sylvestris L.) sapwood. HT of wood in pressurized hot water at 120-170 °C was applied to cause the preferential bond cleavage, whereas HT of wood in oven-dry state in superheated steam at 180-240 °C was performed to create additional covalent cross-links within the cell wall matrix. Removal of cell wall polymers by HT and water leaching reduced the oven-dry dimensions of wood and enhanced the cellulose aggregation during drying. Cellulose aggregation restricted the cell wall shrinkage in circumferential direction, resulting in inhomogeneous shrinkage of the cell wall with only little changes in lumen volume by HT. Cellulose aggregation also reduced the water-saturated dimensions, but a decrease in swelling was only achieved when additional cross-links were formed by HT in dry state. Additional cross-links in the cell wall matrix also resulted in an additional reduction in water sorption at 25 °C and 93% RH. However, this was not caused by a further reduction in the hydroxyl accessibility. Instead, cross-linking was shown to reduce the amount of accessible OH groups that are simultaneously active in sorption, which was explained based on the concept of sorption of water dimers at hydroxyl group pairs at high RH levels.

  • 3. Balea, A
    et al.
    Blanco, A
    Fuente, H
    Concepción, M
    Negro, C
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Hosseinpourpia, Reza
    Mai, C
    Tubek-Lindblom, A
    Hansen, P
    Morphology, properties and recyclability of modified fibres and papers with different chemicals at laboratory and pilot plant trials2015In: 46th Congresso Annuale Aticelca, May 28-29, Sestri Levante-Genova, Italy, Aticelca , 2015, p. 23-31Conference paper (Refereed)
    Abstract [en]

    Fibre+ (2012-2015) is a European project aiming to develop potential treatments for recovered fibre modification capable of improving the recyclability and the properties of recycled papers. This study reports on the results on fibre morphology, paper properties and recyclability of fibres and papers modified with different chemicals and approaches from both laboratory and pilot plant trials. Sixteen modification chemical agents were studied in a set of laboratory trials. The raw material used was 100% recycled paper grade from old corrugated board containers (OCC). The laboratory analysis to evaluate the effectiveness of fibre modifications treatments included FBRM for pre-screening of chemicals, preparation of laboratory control and modified handsheets to a target grammage of 80 g/m2, and measurement of the fibre morphology, recyclability and mechanical and physical properties of the modified handsheets. Based on the results of laboratory testing, Fibre+ modifications pilot plant trials were carried out at a FEX paper machine. Furthermore the effect of the better dispersion of the cPAM using an ECOWIRL was studied. The overall laboratory and pilot plant results were promising for further implementation of the Fibre+ modifications at industrial scale and projection of improvements of fibre and paper properties on the performance of packaging products thereof

  • 4.
    Cristina, Simón
    et al.
    Technical University of Madrid, Spain.
    Francisco, García Fernández
    Technical University of Madrid, Spain.
    Luis, García Esteban
    Technical University of Madrid, Spain.
    Paloma, de Palacios
    Technical University of Madrid, Spain.
    Hosseinpourpia, Reza
    University of Göttingen, Germany.
    Carsten, Mai
    University of Göttingen, Germany.
    Comparison of the saturated salt and dynamic vapor sorption methods in obtaining the sorption properties of Pinus pinea L.2017In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 75, no 6, p. 919-926Article in journal (Refereed)
    Abstract [en]

    Several methods are available for obtaining the sorption isotherms of wood. Among these, the saturated salt and dynamic vapor sorption methods are the most frequently used  ones. For the first time, the hygroscopic response of wood obtained using these two methods is compared. This is done by determining the 35 and 50°C adsorption isotherms of juvenile and mature wood of Pinus pinea L. The hygroscopic behavior of the two types of wood is different, as the mature wood has a higher moisture content than the juvenile wood in the isotherms studied. Comparison of the static saturated salt method and dynamic vapor sorption shows few significant differences between the equilibrium moisture content obtained by each method during the adsorption process, both in a point by point comparison and in the comparison of quadratic polynomial forms of the Guggenheim Anderson-de Boer model. Moreover, in both methods the point of relative humidity from which multilayer sorption predominates over monolayer sorption is similar.

  • 5.
    Danesh, Mohammad Amin
    et al.
    Islamic Azad University, Iran.
    Ziaei Tabari, Hassan
    Islamic Azad University, Iran.
    Hosseinpourpia, Reza
    Georg-August University, Germany.
    Nazarnezhad, Noradin
    Sari Agricultural Science and Natural Resources University, Iran.
    Shams, Morteza
    Islamic Azad University, Iran.
    Investigation of the morphological and thermal properties of waste newsprint/recycled polypropylene/nanoclay composite2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 1, p. 936-945Article in journal (Refereed)
    Abstract [en]

    The main objective of this research was to study the potential of waste polypropylene and waste newsprint fiber for making wood-plastic nanocomposites. We used 30 wt.% waste newsprint fiber and 10 wt.% compatilizer in this study. Nanoclay was used at two levels: 2.5 and 5% by wt. Materials were mixed with either recycled or virgin polypropylene. The effects of nanoclay (NC) on the mechanical and thermal properties were also studied. The improvements in tensile properties of the blended composites with the addition of NC were further supported by Scanning Electron Microscope (SEM) micrographs and X-Ray Diffraction (XRD) data. Thermal degradation behavior of the composites showed that the degradation temperatures shifted to higher values after addition of nanoclay. The XRD data showed that the relative intercalation of composites with 2.5% nanoclay was higher than 5% nanoclay. The experimental results demonstrated that the waste materials could be used as appropriate alternative raw materials for making low cost wood-plastic composites (WPCs).

  • 6.
    Esteban, Luis García
    et al.
    Ciudad Universitaria, Spain.
    Simón, Cristina
    Ciudad Universitaria, Spain.
    Fernández, Francisco García
    Ciudad Universitaria, Spain.
    Palacios, Paloma de
    Ciudad Universitaria, Spain.
    Martín-Sampedro, Raquel
    Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain.
    Eugenio, María Eugenia
    Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain.
    Hosseinpourpia, Reza
    Georg August University, Germany.
    Juvenile and mature wood of Abies pinsapoBoissie: sorption and thermodynamic properties2015In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 49, no 4, p. 725-738Article in journal (Refereed)
    Abstract [en]

    For industrial processes, it is important to study the hygroscopicity and thermodynamic properties of juvenile and mature wood. Samples of Abies pinsapo Boiss. collected in the natural areas of the species in Spain were used to study these properties in both types of wood. The equilibrium moisture contents were obtained, and the 15, 35 and 50 °C isotherms were plotted following the Guggenheim–Anderson–Boer–Dent model. The thermodynamic parameters were calculated using the integration method of the Clausius–Clapeyron equation. Chemical analyses, infrared spectra and X-ray diffractograms were applied to assess chemical modifications and possible changes in the cell wall structure. The chemical composition of the mature wood shows a decrease in the lignin and hemicelluloses content and an increase in the extracts and α-cellulose. The sorption isotherms for the three temperatures studied are higher in the mature wood than in the juvenile wood. Causes of this include the higher content of α-cellulose, the higher crystallinity index and the shorter crystallite length in the mature wood. No difference was found between the juvenile and mature wood in relation to the point of inflexion where the multilayer starts to predominate over the monolayer (approximately 30 %). In terms of the thermodynamic properties, the heat involved is greater in desorption than in adsorption, and more heat is involved in the mature wood than in the juvenile wood.

  • 7.
    Hosseini, Payam
    et al.
    Sharif University of Technology, Iran ; Alaodoleh Semnani Institute of Higher Education, Iran.
    Hosseinpourpia, Reza
    Georg-August University, Germany.
    Pajum, Arash
    University of Tehran, Iran.
    Khodavirdi, Mohammad Mahdi
    University of Tehran, Iran.
    Izadi, Hamed
    Sharif University of Technology, Iran.
    Vaezi, Ali
    Politecnico di Milano, Italy.
    Effect of nano-particles and aminosilane interaction on the performances of cement-based composites: An experimental study2014In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 66, p. 113-124Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to experimentally investigate the interaction between a low replacement ratio of different nano-particles (SiO2, Al2O3, clay, and CaCO3) and aminosilane in the matrices of cement paste and mortar. Results showed that the optimum content of aminosilane for improving the 28-day compressive strength of cement mortar was 0.75% (by weight of the total binder). The utilization of nano-SiO2 and nano-clay particles improved the strengths of the cement mortar containing hybrid systems of nano-particles/aminosilane at early (7 days) and middle curing ages (28 and 91 days). The 28-day compressive strength enhancement of cement mortar with hybrid systems of nano-SiO2/aminosilane and nano-clay/aminosilane was about 19% and 20%, respectively. Additionally, the application of aminosilane with nano-CaCO3 and nano-Al2O3 particles showed lower efficacy on mechanical performance of the cement-based composites in comparison with nano-clay and nano-SiO2. Despite the fact that the utilization of aminosilane with and without different nano-particles enhanced the flowability of the cement paste and mortar, it reduced the electrical resistivity of the cement mortar. In this regard, the minimum electrical resistivity was achieved for specimens with only aminosilane. This reduction was about 19.5% for samples containing 0.75% aminosilane for a curing time of 28 days.

  • 8.
    Hosseinpourpia, Reza
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. University of Göttingen, Germany.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Holstein, Nonna
    University of Göttingen, Germany.
    Mai, Carsten
    University of Göttingen, Germany.
    Dynamic vapour sorption and water-related properties of thermally modified Scots pine (Pinus sylvestris L.) wood pre-treated with proton acid2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 138, p. 161-168Article in journal (Refereed)
    Abstract [en]

    This study investigates the effect of proton acid pre-treatment and subsequent thermal modification at relatively low temperatures (up to 180 °C) on wood with respect to dimensional stability and water vapour sorption properties. The effects are compared to those of solely thermally-modified wood at higher temperatures (up to 250 °C). Scots pine sapwood (P. sylvestris L.) was impregnated with a proton acid or demineralised water, and subsequently, thermally modified to various mass losses (ML). Acid pre-treatment and thermal modification improved the dimensional stability and reduced the equilibrium moisture content (EMC) until certain ML. Excess surface work (ESW) obtained from vapour sorption studies indicated that, at comparable ML, the acid pre-treatment reduced the available sorption sites as compared to sole thermal treatment. Samples pre-treated with acid also showed stronger decreasing courses of EMC- and ESW-ratios than sole thermally modified ones. This was attributed to degradation of amorphous wood polymers and a stiffer matrix due to cross-linking of the cell wall polymers as a consequence of acid pre-treatment. Electron spin resonance (ESR) analysis indicated that acid pre-treatment did not enhance the concentration of phenoxy radicals, whereas thermally modified wood showed a considerably higher concentration of phenoxy radicals, suggesting that high radical density cannot be used as an indicator for high matrix stiffness.

  • 9.
    Hosseinpourpia, Reza
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Mai, C
    Georg-August-University Gottingen, Germany.
    Analysis of the vapour sorption behaviour of wood modified with thermosetting resins with Hailwood-Horrobin and Excess Surface Work models2018In: 29th International Conference on Wood Science and Technology, ICWST 2018: Implementation of Wood Science in Woodworking Sector - Proceedings / [ed] Spanic N.,Zupcic I., University of Zagreb , 2018, p. 87-92Conference paper (Refereed)
    Abstract [en]

    Wood modification is a well-known technology to enhance the dimensional stability of wood and the resistance to abiotic and biotic degradation. Impregnation modification of wood with thermosetting resins, such as melamine formaldehyde (MF) or phenol formaldehyde (PF), alters the material properties of wood through formation of a three-dimensional network within the cell wall. This work investigates the vapour sorption behaviour of Scots pine (Pinus sylvestris L.) micro-veneers modified with MF and PF resins by means of Hailwood-Horrobin (H-H) and excess surface work (ESW) models. The analysed sorption data indicated that the available sorption sites were increased in the modified samples compared to the unmodified controls due to an increase of the monolayer sorption. However, modification resulted in a considerable reduction of the multilayer sorption. This could be attributed to the formation of a rigid, three-dimensional corset within the cell wall formed by auto-polymerization reactions of resin monomers and oligomers, which is known to reduce the cell wall swell-ability upon water absorption.

  • 10.
    Hosseinpourpia, Reza
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Dynamic vapour sorption of wood and holocellulose modified with thermosetting resins2016In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, no 1, p. 165-178Article in journal (Refereed)
    Abstract [en]

    Micro-veneers of wood and holocellulose (HC) were modified with the thermosetting resins phenol formaldehyde and melamine formaldehyde. The dynamic water vapour sorption of the modified and untreated veneers was studied in a dynamic vapour sorption apparatus to assess the effects of resin modification. The adsorption of wood and HC as well as the desorption of wood was little affected by the modification in the low relative humidity (RH) range but decreased in the RH range above 60–70 %. The desorption isotherm of HC, however, was increased in the RH range of 15–80 % due to modification. Resin modification gradually decreased the EMC ratio of wood and HC and also influenced the moisture increment, equilibrium time and sorption rate in RH range above 50–60 % RH for wood and above 70–80 % RH for HC. HC exhibited a clearly lower hysteresis than wood. Modification of wood slightly reduced hysteresis compared to untreated wood, but modification of HC clearly increased hysteresis about to the same extent as that of wood. This indicates that the stiffening effect of lignin and thermosetting resins reduces the flexibility of the HC matrix, which results in increased hysteresis.

  • 11.
    Hosseinpourpia, Reza
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Dynamic water vapour sorption properties and dimensional stability of thermally and acid-treated Scots pine (Pinus sylvestris L.)2015In: 69th Forest Products Society (FPS) International Convention, June 10-12, Atlanta, GA, Forest Products Society , 2015Conference paper (Refereed)
    Abstract [en]

    In order to accelerate the thermal modification process, Scots pine sapwood samples were subjected to two types of treatments. One group of samples was impregnated with water and exposed to 220oC and the second group was initially treated with low concentration of acids (1 mol l-1 AlCl3 and a mixture of 0.5 mol l-1 H2SO4 and 1 mol l-1 AlCl3), and then heated at different temperatures (180 and 120oC) to achieve comparable mass loss (ML) levels. The water vapour sorption isotherms of the thermally and acid-treated wood samples were determined using a dynamic vapour sorption (DVS) apparatus. Increasing the temperature in both thermally and acid-treated samples resulted in ML attributable to hemicelluloses degradation. As a result thereof, dimensional stability and reduction in the hygroscopicity of wood were observed. Acid-treated samples heated at lower temperature exhibited similar water sorption behaviour as water-treated samples subjected to considerably higher temperature. The sorption data were analysed using the Hailwood-Horrobin (H-H) and excess surface work (ESW) models. The data indicated that the monolayer and polylayer sorption were reduced by the acid and thermal treatments, but acid treatment reduced the monolyer sorption stronger than the thermal. The effect of thermal and acid treatments on the flexibility of the cell wall matrix could not be fully distinguished.

  • 12.
    Hosseinpourpia, Reza
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Mai, Carsten
    Effect of lignin and hemicelluloses removal on dynamic water vapour sorption behavior of wood2017In: IUFRO Division 5 Conference, 12-14 June, 2017 - Vancouver, British Columbia: Final program, proceedings and abstracts, IUFRO Division 5 Conference , 2017Conference paper (Refereed)
    Abstract [en]

    Water-related properties of wood are strongly depended on the sorption behavior of its hygroscopic polymers such as cellulose, hemicelluloses and lignin. To assess the sorption performance of wood matrix in the absence of hemicelluloses and lignin, micro-veneers of Scots pine (Pinus sylvestris L.) were hydrolyzed with sulphuric acid and delignified with sodium chlorite and acetic acid, respectively. The dynamic water vapour sorption of the hydrolyzed, delignified and untreated veneers was studied in a dynamic vapour sorption (DVS) apparatus. The moisture adsorption of hydrolyzed veneers was decreased in the relative humidity (RH) range above 60-70 %. Delignified veneers, however, showed obviously higher moisture adsorption at RH above 70%, as compared to untreated controls. Hydrolyzed and untreated veneers exhibited a comparable hysteresis, while delignified veneers showed a considerably lower hysteresis in comparison to them. This explains that, despite the fact that the hydrophilic hemicelluloses influence the moisture sorption of wood, the expand-ability of the cell wall matrix is mainly controlled by lignin.

  • 13.
    Hosseinpourpia, Reza
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Georg-August-University, Germany.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Mai, Carsten
    Georg-August-University, Germany.
    Effects of acid pre-treatments on the swelling and vapor sorption of thermally modified Scots pine (Pinus sylvestris L.) wood2018In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 1, p. 331-345Article in journal (Refereed)
    Abstract [en]

    Scots pine sapwood samples were pre-treated with a Lewis acid (AlCl3) and a combination of Lewis and protonic acids (AlCl3 and H2SO4), and were subsequently exposed to respective temperatures of 180 °C and 120 °C for establishing a comparable mass loss with those impregnated with demineralized water and solely thermally modified at 220 °C. Water impregnated samples dried at 120 °C also served as controls. The swelling behavior of all wood samples was examined with respect to maximum swelling in water, anti-swelling efficiency (ASE), shrinkage, and dynamic water vapor sorption at relative humidity ranges of 0% to 95%. The thermal modification at 220 °C diminished swelling and moisture adsorption, and also reduced moisture increment and decrement compared with the unmodified control. However, it was less obvious than both acid pre-treated samples. Excess surface work and Hailwood-Horrobin results calculated from water vapor sorption studies demonstrated that, at comparable mass loss, the available sorption sites were reduced to a greater extent by Lewis acid and combination of Lewis and protonic acids pre-treatment than the sole thermal treatment. This was attributed to more pronounced degradation of polysaccharides, mainly hemicelluloses and amorphous parts of cellulose, and to cross-linking of cell wall polymers due to the acid pre-treatments.

  • 14.
    Hosseinpourpia, Reza
    et al.
    Georg August University Göttingen, Germany.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Mai, Carsten
    Georg August University Göttingen, Germany.
    Tensile strength of handsheets from recovered fibers treated with N-methylol melamine and 1,3-dimethylol-4,5-dihydroxyethyleneurea2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 3, article id 41290Article in journal (Refereed)
    Abstract [en]

    The main objective of this study was to assess the effect of two amino resins, N-methylol melamine (NMM) and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), on the intrafiber and interfiber strengths and water absorption of two types of waste paper categories, office paper (OP), and old corrugated containers (OCCs). The tensile strength of individual fibers measured at zero span was reduced by increases in the resin concentrations. The dry tensile strengths of the recovered handsheets measured at a finite span were enhanced with increases in the weight percentage gain of the resins. The increasing of the resin concentration also significantly improved the intrabonding of the OP and OCCs in moist measuring conditions. The water absorption of the handsheets considerably decreased at the higher concentration of the thermosetting resins, especially with NMM. The results are promising for the use of NMM- and DMDHEU-treated recovered fibers as an alternative fiber resource for the production of laminated paper and also for the use of DMDHEU as a new N-methylol compound for laminated paper.

  • 15.
    Hosseinpourpia, Reza
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Georg-August-University, Germany.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Mai, Carsten
    Georg-August-University, Gemany.
    Hemmilä, Venla
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Effect of Bio-Based Additives on Physico-Mechanical Properties of Medium Density Fibreboards2017In: 28th International Conference on Wood Science and Technology (ICWST), Zagreb, Croatia, 7-8 December, 2017 / [ed] Ivica Zupcic; Vjekoslav Zivkovic; Josip Miklecic, University of Zagreb, Faculty of Forestry , 2017, p. 153-158Conference paper (Refereed)
    Abstract [en]

    Dimensional stability of wood-based panels is generally improved with application of suitable additives. Most of these additives, such as paraffin wax, are petroleum-based and with relatively high cost, and therefore, it is desirable to develop low-cost and effective substitutes from renewable resources. This work studied the potential of using a renewable water-repellent additive, such as tall oil fatty acid, for lab-scale manufacturing of medium density fibreboards (MDF). Tall oil fatty acid (TOFA) was used at 1 and 3% w/w of urea formaldehyde (UF) resin. MDF panels with similar concentrations of paraffin wax (wax) and panels without adding a water-repellent agent were served as controls. It was assessed the dimensional stability of the panels in terms of thickness swelling and water uptake after 4 and 24h immersion in water, and their mechanical performance in terms of modulus of elasticity, modulus of rupture and internal bonding. Results showed no obvious differences in the strength behaviour of the panels by addition of water-repellent agents. Dimensional stability, however, considerably improved by addition of TOFA, but it was still inferior when compared to that provided by wax.   

  • 16.
    Hosseinpourpia, Reza
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Parsland, Charlotte
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Utilization of different tall oils for improving the water resistance of cellulosic fibers2019In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 136, no 13, article id 47303Article in journal (Refereed)
    Abstract [en]

    This study was conducted to assess the effect of the pulping by-products crude tall oil (CTO), distilled tall oil (DTO), andtall oil fatty acid (TOFA) on dynamic water vapor sorption behavior, interfiber strength, and thermal stability of cellulosic paper-sheets.The results were compared against those obtained in cellulose papers treated with the conventional petroleum-derived hydrophobicagent hydrowax and in untreated ones. The tall oil treatments caused strong reduction in equilibrium moisture content of the paper-sheets during adsorption and desorption runs. The same trend was noticed for the hydrowax-treated papers, however, it was lesspronounced than the CTO-treated and DTO-treated samples in the relative humidity range of 75–95%. The sorption hysteresis was con-siderably decreased after the treatments. The ultimate dry-tensile strengths of the paper-sheets were significantly reduced by TOFA andhydrowax treatments, while CTO and DTO showed comparable strength as that of untreated control. The ultimate wet-strengths of thepaper-sheets were improved after the treatments. The thermal stability of the specimens was improved by the tall oil treatments, and thehydrowax-treated samples illustrated lower degradation temperature than the untreated control. The results are promising for the use oftall oils as alternative hydrophobic agents of cellulosicfiber-based products, such as wood panels and paper packaging.

  • 17.
    Hosseinpourpia, Reza
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Echart, Arantzazu Santamaria
    University of the Basque Country UPV/EHU, Spain.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Gabilondo, Nagore
    University of the Basque Country UPV/EHU, Spain.
    Eceiza, Arantxa
    University of the Basque Country UPV/EHU, Spain.
    Modification of Pea Starch and Dextrin Polymers with Isocyanate Functional Groups2018In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 10, no 9, article id 939Article in journal (Refereed)
    Abstract [en]

    Pea starch and dextrin polymers were modified through the unequal reactivity of isocyanate groups in isophorone diisocyanate (IPDI) monomer. The presence of both urethane and isocyanate functionalities in starch and dextrin after modification were confirmed by Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR). The degree of substitution (DS) was calculated using elemental analysis data and showed higher DS values in modified dextrin than modified starch. The onsets of thermal degradation and temperatures at maximum mass losses were improved after modification of both starch and dextrin polymers compared to unmodified ones. Glass transition temperatures (Tg) of modified starch and dextrin were lower than unmodified control ones, and this was more pronounced in modified dextrin at a high molar ratio. Dynamic water vapor sorption of starch and dextrin polymers indicated a slight reduction in moisture sorption of modified starch, but considerably lower moisture sorption in modified dextrin as compared to that of unmodified ones.

  • 18.
    Hosseinpourpia, Reza
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Göttingen university, Germany.
    Mai, Carsten
    Dynamic water vapour sorption properties of wood cell wall polymer constituents2015In: COST FP1303 (Performance of bio-based building materials) / [ed] Dennis Jones, Christian Brischke, Jaan Kers, Triinu Poltimäe and Joachim Schmid, SP Technical Research Institute of Sweden , 2015, p. 42-44Conference paper (Refereed)
    Abstract [en]

    Lignin, cellulose and hemicelluloses have main roles on swelling and shrinkage of wood products. Interaction of these components with moisture has an important effect on market-friendly when the wood is subjected to the outside utilizations. In the heterogeneous structure of wood, sorption and desorption are occurred in different stages and it calls hysteresis. Hysteresis is a characteristic result from a moisture/temperature/time-dependent, slow, non-equilibrium, swelling-related conformational change, which is facilitated by increasing free volume and mobility in a polymer that is being plasticized during sorption that usually progresses through the stage of water clustering (Reina et al. 2001). Cell wall polymers of wood have a different behavior in the face of moisture in terms of sorption, desorption and hysteresis (Engelund et al. 2013).

    In order to better comprehension of the effect of cell wall material such as lignin, cellulose and hemicelluloses, Scots pine micro-veneers were subjected to hydrolysis with sulphuric acid or delignification with acidic sodium chlorite, as previously described (Klüppel and Mai 2012). Then the hemicelluloses were isolated from the delignified veneers according to the chloride method. The commercial lignin was also used after dialysis tubing. The water adsorption and desorption mechanism of delignified and hydrolysed veneers as well as cell wall polymers such as cellulose, hemicelluloses and lignin were determined using a dynamic vapour sorption (DVS) apparatus.

    The hydrolysed veneers were resulted in obviously lower moisture content in adsorption and desorption processes with increasing the relative humidity (RH) (Fig. 1a). While, delignified veneers showed slightly higher moisture content compared to control with increasing the ambient moisture until 70% RH and then considerably higher until 95% RH. Control specimens shown higher hysteresis than hydrolysed veneers and also higher hysteresis than delignified veneers after hygroscopic range (Fig. 1b). Moisture content of cell wall constituents in various relative humidity exhibited the higher moisture sorption and desorption of cellulose than lignin, however, hemicelluloses illustrated the significantly higher moisture content than other two cell wall polymers which might be attributed to the softening of hemicelluloses in higher relative humidity (Fig. 2a,b,c). Lignin showed higher hysteresis than cellulose in different relative humidity. Hemicellulose demonstrated the relatively low hysteresis until 50% RH, and with increasing the ambient pressure from 60% RH the hemicelluloses exhibited the extremely higher hysteresis than other cell wall polymers.

  • 19.
    Hosseinpourpia, Reza
    et al.
    Georg-August-University Göttingen.
    Mai, Carsten
    Georg-August-University Göttingen.
    Mode of action of brown rot decay resistance in phenol-formaldehyde-modified wood: resistance to Fenton’s reagent2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 3, p. 253-259Article in journal (Refereed)
    Abstract [en]

    The mode of action of phenol-formaldehyde (PF)-modified wood has been investigated with respect to its resistance to brown rot decay. The Fenton reaction is assumed to play a key role in the initial brown rot decay. Pine microveneers were modified to various weight percent gains (WPG) with low molecular weight PF and exposed to a solution containing Fenton’s reagent. The mass loss (ML) and tensile strength loss (TSL) as well as the decomposition of hydrogen peroxide within the incubation time decreased with the increasing WPG of the veneers. Incubation of untreated and PF-modified veneers in acetate buffer containing ferric ions without H2O2 revealed that the modification strongly reduces the uptake of iron by the wood cell wall. Further studies indicated that lignin promotes the decay of wood by Fenton’s reagent. The reason for the enhanced resistance of modified wood to the Fenton reaction is attributable to the impeded diffusion of iron ions into the cell wall rather than to the blocking of free phenolic sites of lignin, which accelerate redox cycling of iron.

  • 20.
    Hosseinpourpia, Reza
    et al.
    Georg-August-University Göttingen.
    Mai, Carsten
    Georg-August-University Göttingen.
    Mode of action of brown rot decay resistance of acetylated wood: resistance to Fenton’s reagent2016In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, no 2, p. 413-426Article in journal (Refereed)
    Abstract [en]

    Acetylation is known to enhance the resistance of wood to brown rot fungi. As initial decay by some brown rot fungi is assumed to be caused by the Fenton reaction, pine micro-veneers acetylated to various weight percent gains (WPG) were exposed in a solution containing iron ions and hydrogen peroxide, i.e., Fenton’s reagent. Mass loss and tensile strength loss as well as the decomposition of hydrogen peroxide within the incubation time decreased with increasing WPG of the veneers. Incubation of untreated and acetylated veneers in acetate buffer containing ferric ions without H2O2 revealed that the modification strongly reduced the uptake of Fe ions by the wood cell wall. FT-IR analysis indicated oxidation of the unmodified control veneers but did not show predominant decay of specific cell wall components. Spectra of acetylated veneers did not reveal any significant changes induced by Fenton’s reagent. It was concluded that one possible reason for the enhanced resistance of acetylated wood to the Fenton reaction could be the reduced or almost completely prevented uptake of Fe ions by the wood cell wall.

  • 21.
    Hosseinpourpia, Reza
    et al.
    Georg-August-University Göttingen, Germany.
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Mode of action of brown rot decay resistance of thermally modified wood: resistance to Fenton’s reagent2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 7, p. 691-697Article in journal (Refereed)
    Abstract [en]

    The resistance of heat treated (HT) wood to brown rot fungi has been investigated, while the role of the Fenton reaction (FR) in the initial phase of degradation was in focus. Micro-veneers made of Scots pine, were HT with various intensities and their mass losses (MLHT) were determined before soaking with a solution of Fenton’s reagent containing Fe ions and hydrogen peroxide. The mass loss of the veneers treated that way (MLFT), their tensile strength loss (TSLFT) and the H2O2 decomposition were observed. The MLFT, TSLFT, and H2O2 loss decreased with increasing MLHT of the veneers. Soaking of the veneers in acetate buffer containing only Fe without H2O2 revealed that the heat treatment (HT) strongly reduces the Fe uptake by the cell walls. FTIR spectroscopy indicated oxidation of the unmodified control veneers but did not reveal predominant decay of cell wall components; the HT veneers were not changed at all due to FR. It was concluded that the reason for the enhanced resistance of HT wood to FR is attributable to hindered diffusion of Fe ions into the wood cell wall.

  • 22.
    Hosseinpourpia, Reza
    et al.
    Islamic Azad University, Iran ; Georg-August University, Germany.
    Hosseini, Payam
    Sharif University of Technology, Iran.
    Mofidian, Seyedehrashin
    Mazandaran University of Science and Technology, Iran.
    Hosseinpourpia, Rezvan
    Islamic Azad University, Iran.
    Varshoee, Ali
    Islamic Azad University, Iran.
    Influence of Nanosilica on Properties of Green Cementitious Composites Filled with Waste Sulfite Pulp Fiber and Aminosilane2014In: The Arabian Journal for Science and Engineering, ISSN 1319-8025, Vol. 39, no 4, p. 2631-2640Article in journal (Refereed)
    Abstract [en]

    Developments in the field of green cement-based products are characterized as an important approach to sustainable development and are being devoted much attention by the construction industry. Numerous types of materials are utilized; however, based on other published studies, the use of waste material as a filler normally deteriorates the performance of cementitious products. Appropriate additives thus need to be employed to improve the performances and properties of green products. As a consequence, the aim of this study has been to investigate the properties of a novel green cement-based composite—a hybrid system composed of cement, waste natural fiber, silica nano-particles, and aminosilane. Experiments were performed to assess the physical properties (density and flowability), mechanical properties (compressive strength and bending performance), and microstructural properties (as determined by scanning electron microscopy) of the cement sheets. The results demonstrated an improvement in the mechanical and microstructural properties of green cement-based composites by using this hybrid system.

  • 23.
    Hosseinpourpia, Reza
    et al.
    Islamic Azad University, Iran.
    Varshoee, Ali
    Islamic Azad University, Iran.
    Soltani, Mojtaba
    Islamic Azad University, Iran.
    Hosseini, Payam
    Sharif University of Technology, Iran.
    Effects of sulfite waste fibers incorporating silica nano-particles on mechanical and microstructural properties of cementitious composite2010In: 2nd International Conference on Composites: Characterization, Fabrication and Application, 2010, p. 431-436Conference paper (Refereed)
    Abstract [en]

    Natural fibers are one of the most appropriate alternatives for designation and production of structural panels due to low final production cost. However a principal point is the strength loss caused by usage of these fibers in the matrix of cement based composites. Hence, a simple and cheap method should be applied to develop the properties of these fibers. Therefore, in this study by application of sulfite waste (along with waste management in the wood and paper industries) and usage of low-dosage silica nanoparticles (in order to enhance the interfacial transition zone of the cement-fiber paste), production of cement based sheets reinforced with natural fibers and silica nano-particles are investigated. Alongside, flexural strength and microstructure of sheets are examined by calculating the Modulus of Rupture (MOR) and Modulus of Elasticity (MOE), and applying the Scanning Electron Microscopy (SEM), respectively. Results show that mechanical performance and microstructure of cement based composites containing waste natural fibers and silica nano-particles can be improved.

  • 24.
    Hosseinpourpia, Reza
    et al.
    Islamic Azad University, Iran ; Georg-August University, Germany.
    Varshoee, Ali
    Islamic Azad University, Iran.
    Soltani, Mojtaba
    Islamic Azad University, Iran.
    Hosseini, Payam
    Sharif University of Technology, Iran.
    Ziaei Tabari, Hassan
    Islamic Azad University, Iran.
    Production of waste bio-fiber cement-based composites reinforced with nano-SiO2 particles as a substitute for asbestos cement composites2012In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 31, p. 105-111Article in journal (Refereed)
    Abstract [en]

    The environmental impact of asbestos fibers on human health and their consequent safety-related problems indicate that there is a significant need to replace this material in all asbestos-containing products. Many different types of fibers have been introduced to replace asbestos fibers.

    In this study, the performance of silica nano-particles combined with waste paper pulp fibers (sulfite fibers) has been investigated. Different mechanical (compressive and flexural strengths and bending performance), durability (water absorption), physical (bulk density and flowability), and microstructural (scanning electron microscopy) tests were conducted to examine the properties of manufactured green composites.

    The results reveal that the mechanical properties of cement-based composites containing a ternary system of “natural waste fiber–silica nano-particle cement” have been enhanced. Adding silica nano-particles allows the development of green cement-based composites and movement toward sustainable development in the concrete industry.

  • 25.
    Kumar, Anuj
    et al.
    Natural Resources Institute Finland (Luke), Finland.
    Ryparová, Pavla
    Czech Technical University in Prague, Czech Republic.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Prošek, Zdeněk
    Czech Technical University in Prague, Czech Republic.
    Žigone, Jure
    Czech Technical University in Prague, Czech Republic.
    Petrič, Marko
    University of Ljubljana, Slovenia.
    Hydrophobicity and resistance against microorganisms of heat and chemically crosslinked poly(vinyl alcohol) nanofibrous membranes2019In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 360, p. 788-796Article in journal (Refereed)
    Abstract [en]

    Poly(vinyl alcohol) (PVA) is a water-soluble, semi-ionic and biocompatible polymer with excellent chemical and thermal stability. The chemical crosslinking of PVA membrane improve its stability towards humidity and water. In the present work, PVA nanofibrous membranes were fabricated using roller electrospinning techniques. The prepared membranes were crosslinked by heat treatment, glutaraldehyde dipping, and glutaraldehyde vapour. Furthermore, octadecyltrichlorosilane (OTS) treatment was used for hydrophobization of the crosslinked membranes. The prepared crosslinked membranes were analysed by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The hydrophobization of PVA nanofibrous membranes were analysed by employing optical goniometer and auto-dynamic vapour sorption (AVS) techniques. Further, the PVA membranes were tested against algae and mould growth at in-vitro laboratory conditions. The SEM and FTIR results revealed significant differences in the morphology of the PVA nanofibrous membranes and in chemical bond formation due to crosslinking treatments. Water contact angle and AVS data confirmed a hydrophobization of PVA membranes by the treatments.

  • 26. Reshadi Nejad, H
    et al.
    Hosseinpourpia, Reza
    Arash, Pajum
    Interaction of aminopropyltri-ethoxysilane and amorphous nano-SiO2 particles in the matrix of cement-based materials2012In: 3rd Advances in Cement‐based Materials: Characterization, Processing, Modeling and Sensing Austin, TX, June 10‐12, 2012, 2012, p. 112-117Conference paper (Refereed)
  • 27.
    Soltani, Abolfazl
    et al.
    Shahid Rajee Teacher Training University, Iran.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Taghiyari, Hamid R.
    Shahid Rajee Teacher Training University, Iran.
    Ghaffari, Ehsan
    Shahid Rajee Teacher Training University, Iran.
    Effects of heat-treatment and nano-wollastonite impregnation on fire properties of solid wood2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 4, p. 8953-8967Article in journal (Refereed)
    Abstract [en]

    The effects of nano-wollastonite (NW) suspension impregnation on the fire-retarding properties of heat-treated solid wood of three species (beech, poplar, fir) were studied. Heat treatment was performed at two temperatures of 180 °C and 200 °C. Impregnation was carried out at a pressure of 3 bars for 30 min. The fire properties included ignition time, glowing time, back-darkening, back-splitting, back-firing, and length and width of the burnt area. Both impregnation with NW and heat-treatment generally improved all fire-retarding properties, although not always to a significant level. As a mineral material, NW acted like a physical shield against fire penetration into the texture of wood specimens, thus improving fire properties. Moreover, the high thermal conductivity coefficient of wollastonite increased the thermal conductivity of wood, therefore preventing the accumulation of heat at the point nearest to a piloted flame and contributing to the improvement of fire properties. The chemical degradation of wood cell components caused by heat-treatment further improved the fire properties. Cluster analysis indicated the significant effect of species on fire properties. Significant R-square values were found amongst fire properties related to the spread of fire on the surface of specimens. The combination of thermal modification and impregnation with NW provides suitable fire properties for solid wood.

  • 28.
    Taghiyari, Hamid Reza
    et al.
    Shahid Rajaee Teacher Training University, Iran.
    Elyasi, Abdollah
    University of Tehran, Iran.
    Doost-Hoseini, Kazem
    University of Tehran, Iran.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Georg August University Gottingen, Germany.
    Correlation between gas and liquid permeability with noise reduction coefficient in insulation boards made from sugar cane bagasse2017In: Bulgarian Journal of Agricultural Science, ISSN 1310-0351, Vol. 23, no 3, p. 674-681Article in journal (Refereed)
    Abstract [en]

    Specific gas and liquid permeability, as well as noise reduction coefficients, in insulating boards made of sugar-cane bagasse were studied here. Urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF) were used to produce homogeneous as well as three-layered insulating boards with three densities of 0.3, 0.4, and 0.5 g/cm3. The obtained results indicated that MUF slightly decreased gas and liquid permeability, but it did not significantly affect the noise reduction coefficients. Gas and liquid permeability were considerably affected by the density of the boards, due to the compression between the bagasse particles and less spaces and voids to let the fluids to pass through. However, noise reduction coefficients were significantly affected both by the density, as well as the board-type. More compression between the particles and the consequent less space between the bagasse particles entangled the waves; further more, the sudden change between the layers in the three-layered boards formed a barrier towards transmission of waves.

  • 29.
    Taghiyari, Hamid Reza
    et al.
    Shahid Rajaee University, Iran.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Jahangiri, Asghar
    Rabie, Davood
    Effects of Nano-Wollastonite Impregnation on Fire Properties of Some Thermally-Treated Solid Wood Species2017In: Proceedings IRG Annual Meeting, IRG/WP 17-40771, International research group on wood protection , 2017Conference paper (Refereed)
    Abstract [en]

    The effects of nano-wollastonite (NW) suspension impregnation on the fire-retarding properties of heat-treated solid wood of three species (beech, poplar, fir) were studied. Heat treatment was performed at two temperatures of 180 °C and 200 °C. Impregnation was carried out at a pressure of 3 bars for 30 min. The fire properties included ignition time, glowing time, back-darkening, back-splitting, back-firing, and length and width of the burnt area. Both impregnation with NW and heat-treatment generally improved all fire-retarding properties, although not always to a significant level. As a mineral material, NW acted like a physical shield against fire penetration into the texture of wood specimens, thus improving fire properties. Moreover, the high thermal conductivity coefficient of wollastonite increased the thermal conductivity of wood, therefore preventing the accumulation of heat at the point nearest to a piloted flame and contributing to the improvement of fire properties. The chemical degradation of wood cell components caused by heat-treatment further improved the fire properties. Cluster analysis indicated the significant effect of species on fire properties. Significant R-square values were found amongst fire properties related to the spread of fire on the surface of specimens. The combination of thermal modification and impregnation with NW provides suitable fire properties for solid wood.

  • 30. Varshoee, Ali
    et al.
    Hosseinpourpia, Reza
    Soltani, Mojtaba
    Talaeipoor, Mohammad
    The Effect of Coupling Agent on Water Absorption Property of Natural Fiber-Cement Nanocomposites2011In: Iranian Journal of Sciences and Techniques in Natural Resources, Vol. 6, no 2, p. 127-137Article in journal (Refereed)
    Abstract [fa]

    این تحقیق به منظور بررسی تاٌثیر ماده جفت کننده بر خصوصیات میکروسکوپی و جذب آب در نانو کامپوزیتهاي ساخته شده از الیاف دورریز خمیر کاغذ سولفیت و سیمان انجام گرفته است. در این پژوهش هشت تیمار شامل تاٌثیر دو سطح ماده جفتکننده بر پایه آمینو سیلان (0 و6 درصد وزنی الیاف) و چهار سطح نانو سیلیس (0 ،5/0 ،1 و 3 درصد جایگزینی وزنی سیمان) به عنوان عوامل متغیر و میزان الیاف و آب به ترتیب در سطح 10 درصد و نسبت یک به یک وزنی سیمان ثابت، بر خصوصیت جذب آب نمونه هاي ساخته شده مورد بررسی قرار گرفت. کلیه نمونه ها مطابق با استاندارد Part: 1881 BS 5 1983-122 در سه مرحله جامد، مایع و اختلاط نهایی ساخته و مورد آزمایش قرار گرفتند. تصاویر میکروسکوپی SEM جهت بررسی خواص ریز ساختاري کامپوزیتها از نمونه ها تهیه شد. نتایج به دست آمده نشان داد که با افزایش مقدار نانو ذرات سیلیس، جذب آب در مقایسه با نمونه شاهد کاهش یافت، همچنین افزودن ماده جفت کننده موجب افزایش جذب آب گردید. از طرفی اثر متقابل نانوذرات سیلیس و ماده جفت کننده در مقایسه با نمونههاي شاهد که حاوي مقدار 10 درصد الیاف آزبست بودهاند، نشان دهنده کاهش میزان جذب آب بوده است. نمونههاي حاوي 3 درصد نانو ذرات سیلیس و 6 درصد ماده جفتکننده داراي کمترین میزان جذب آب بوده اند. همچنین تصاویر SEM حاکی از بهبود ریزساختاري نانوکامپوزیتها با افزودن ماده جفت کننده بود.

  • 31. Ziaei Tabari, Hassan
    et al.
    Nourbakhsh, Amir
    Hosseinpourpia, Reza
    Danesh, Mohammad Amin
    Evaluation of mechanical and morphological behavior of polypropylene/wood fiber nanocomposite prepared by melts compounding2010In: International Conference on Nanotechnology and Biosensors, 28th to 30th December 2010, Hong Kong, Singapore, 2010, Vol. 2, p. 20-23Conference paper (Refereed)
    Abstract [en]

    Weak flexural properties of wood plastic composites(WPCs) limit their structural application. Recentlyinvestigation of nano particles looks promising to enhancebending properties of WPCs. In this study, the authors haveinvestigated the effect of different concentrations of nanoclay(modified montmorillonite) and coupling agent on themechanical and micro-structural properties of polypropylene/wood-fiber composites. We Bath internal mixer in certainprocessing conditions used for making the samples and then allsamples molded using injection molding for making samplesfor performing mechanical measurements. Samples preparedin four different concentration of nanoclay 0, 1, 3 and 5 wt%(total weight) and two different concentrations of maleicanhydride grafting (MAPP) 5 and 10 wt%. Mechanical resultsindicate that both flexural and impact strength of thecomposites increasing in sample containing 3% nano clay. Inother trend, Scanning Electron Microscope (SEM) imagesshow better interaction of wood fibers and polymer matrixwhen the authors added 5 wt% MAPP as coupling agent.

1 - 31 of 31
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