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Fu S.,Northeast Forestry University | Han G.,Northeast Forestry University | Cheng W.,Northeast Forestry University | Deng J.,19 rue Franquet
Advanced Materials Research | Year: 2011

Particleboards bonded with urea formaldehyde (UF) and a combination of UF and methylene diphenyl diisocyanate (MDI) resins were manufactured using wheat straws modified through different steam explosion treatments. The effect of steam explosion treatment, resin system, and mixing ratios of wood and straw materials on the panel properties was investigated. Generally, with steam explosion treatment of straw fibers, panel properties in bending and internal bond (IB) strength increased, thickness swelling (TS) and water absorption (WA) decreased. The bending properties for the panels made from the straws pretreated with 12 h water-soaking were significantly improved at the UF/MDI content level of 5%/1%. The IB strength dramatically increased, while TS and WA decreased with the use of dual resins. With increased weight ratio of wheat straw to wood particles, the bending properties, IB strength, TS and WA deteriorated. Pure wheat straw boards had the lowest properties. Wood particles in substitution for part of straw materials helped improve the panel properties. The results demonstrated that steam explosion modification and/or its combination with UF/MDI dual resin system can be a feasible approach to improve the bonding strength for wheat straw based particleboards. © (2011) Trans Tech Publications.

Mihai M.,Industrial Materials Institute of Canada | Legros N.,Industrial Materials Institute of Canada | Iordan A.,Industrial Materials Institute of Canada | Alemdar A.,19 rue Franquet
Annual Technical Conference - ANTEC, Conference Proceedings | Year: 2011

This paper aims at developing natural fiber biocomposites based on biopolymers reinforced with wood fibers obtained from a thermo-mechanical refining process. Polylactide (PLA) and polylactide/thermoplastic starch blends (PLA/TPS) were used as matrices. TPS content in the PLA/TPS blends was set at 50 wt%. Two wood fiber types were selected, a hardwood (HW) and a softwood (SW), to state the effect of the fiber type on the biocomposite properties. The impact of different additives on biocomposite properties was studied with the purpose to enhance the biopolymer-wood fiber affinity giving the best final mechanical performance. Biocomposites containing 30 wt% of wood fibers were obtained by co-rotating twin-screw extrusion. The properties are described in terms of morphology, thermal, rheological, and mechanical properties.

Migneault S.,Laval University | Koubaa A.,University of Quebec | Nadji H.,University of Quebec | Riedl B.,Laval University | And 2 more authors.
Wood and Fiber Science | Year: 2010

Pulp and paper sludge can be recycled in the manufacture of medium-density fiberboard (MDF) because it contains wood fibers. A comparative study was conducted to evaluate the properties of MDF made from virgin fibers mixed with different pulp and paper sludge sources. A factorial design was used in which factors were mill pulping processes, thermal-mechanical pulping (TMP), chemical-thermal- mechanical pulping (CTMP), and kraft pulping, and percentage of sludge mixed with virgin fibers (0, 25, 50, and 75%). Virgin fibers were obtained from paper birch wood, an underutilized species. Chemical composition, physical characteristics, pH, and buffer capacity of sludge were measured. MDF properties decreased mostly linearly with sludge content. Panel properties negatively correlated with the proportion of nonfibrous material such as ash and extractives. TMP and CTMP sludge sources produced panels of similar quality, and kraft sludge produced the lowest quality. It was concluded that the amount of sludge that can be incorporated into MDF without excessive decrease in panel quality depends on the pulping process. At 25% sludge content, all panels met ANSI quality requirements for MDF used for interior applications. © 2010 by the Society of Wood Science and Technology.

Migneault S.,Laval University | Koubaa A.,University of Quebec | Nadji H.,Laval University | Deng J.,19 rue Franquet | Zhang S.Y.,665 East Mall
Wood and Fiber Science | Year: 2011

Pulp and paper sludge is valuable in fiberboard manufacturing because primary sludge (PS) contains fibers and secondary sludge (SS) has adhesive properties. We evaluated properties of binderless fiberboard made from conventional pulp and paper mill sludge sources using a factorial design in which the factors were SS:PS ratio (1:9, 2:8, and 3:7) and pulping process (thermomechanical [TMP], chemical- thermomechanical [CTMP], and kraft). Sludge was collected, refined, dried, and characterized for chemical composition and fiber length. Internal bond strength of CTMP panels increased 90% and thicknessswell of TMP panels improved 92% with increasing SS content from 10-30%. IR Fourier transform and X-ray photoelectron spectroscopy analyses were conducted to better understand these results. Increased bonding was attributed to presence of proteins and lignin on the sludge fiber surface, which enhanced adhesion during hot pressing, whereas surface contamination decreased bonding efficiency. The TMP formulation at SS:PS ratio 3:7 met the ANSI requirement for basic hardboard. All other formulations were not dimensionally stable enough to meet the standard. The CTMP source resulted in the highest mechanical properties, and thickness swell was similar for the TMP and CTMP pulping processes. The kraft source produced low-integrity and dimensionally unstable panels. © 2011 by the Society of Wood Science and Technology.

Landry V.,19 rue Franquet | Blanchet P.,19 rue Franquet | Zotig L.,Societe Laurentide | Martel T.,19 rue Franquet
Journal of Coatings Technology Research | Year: 2013

The purpose of this study was to investigate the performance of a semitransparent PVDF-acrylic coating on two wood species: Black spruce and White pine. An accelerated aging test was performed on the PVDF-acrylic coating and the results obtained were compared with those obtained for a water-based acrylic coating. Color changes were found to be more significant for the acrylic coating, especially after 1000 h of exposure, and for the White pine panels. Infrared spectroscopy revealed that the acrylic resin was more affected by the accelerated aging test than the PVDF resin, although X-ray photoelectron spectroscopy revealed that PVDF was slightly affected at the extreme surface (first 10 nm). Star-shaped defects were found at the surface of the White pine panels finished with the PVDF-acrylic coating. Experiments revealed that the PVDF-acrylic coating does not seem to be flexible enough to sustain resin exudation or other stresses. © 2012 ACA and OCCA.

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