We investigated the effects of fiber variability, size and content on the fusion characteristics of wood particle-reinforced high-density polyethylene (HDPE). Five types of wood sawdust were used: eastern white cedar, with sapwood, and heartwood treated separately; jack pine divided into wood and bark; and black spruce. Three different fiber length classes were also used. Composite pellets containing wood particles at 25, 35, and 45% by weight with HDPE were made using a co-rotating twin-screw extruder. The pellets were melted and mixed during 7 min in a torque rheometer at 180°C. We also investigated the polymer variation using HDPE, polypropylen (PP), polyvinyl chloride (PVC), and a blend of (80% HDPE+ 20% PP) where wood fiber proportion and length were kept constant. We varied the mixing temperature to reach the melting temperature range of each polymer. Mixing and melting times, maximum torque and stabilized torque were obtained. Adding wood fibers to the HDPE increased processing time and torque energy. At constant fiber length and proportion, torque properties varied with fiber origin. Higher fiber length and proportion increased torque energy and time of stabilization. Thus, using wood fibers with different properties will lead to significant variations in processing, such as in extrusion or injection. The fusion characteristics of wood polymer composite vary among polymers. The PVC showed the highest steady-state torque. The formulation containing a polymer blend of HDPE and PP showed the highest torque energy. This higher torque energy is explained by the interaction of the incompatible polymeric chains of the two thermoplastic polymers. © 2018 Society of Plastics Engineers.

This study evaluated the reinforcement potential of Posidonia oceanica fibres (POF) and deinking paper sludge (DPS) on the thermo-mechanical properties of high density polyethylene (HDPE) binary and hybrid composites. The weight ratios of the fillers (POF and/or DPS) to the polymer were 0:100; 20:80; 30:70 and 40:60 (wt:wt). Maleated polyethylene (MAPE) was added at a proportion of 3% by weight. The chemical composition, structural and thermal properties and morphology of the fillers were investigated by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The mechanical (tensile and impact strength) and thermal properties (TGA and Differential Scanning Calorimetry (DSC)) of the binary and hybrid composites were also investigated. Binary and hybrid composite properties depend on the chemical composition of the fillers (POF and DPS), the filler/matrix interfacial adhesion and the POF: DPS ratio. The tensile modulus and strength of the binary and hybrid composites increased with increasing filler content (POF or/and DPS). A better interfacial adhesion between fillers and matrix was achieved in the presence of MAPE. HDPE/POF/MAPE composites achieved the highest tensile modulus and strength with 40% POF. But lower thermal stability, ductility and impact strength were found with the addition of the POF. However, the thermal stability, crystallinity, ductility and toughness improved in HDPE/POF/DPS/MAPE hybrid composites due to the addition of DPS or the substitution of POF by DPS. © 2018 Elsevier B.V.

Deinking paper sludge (DPS)/high density polyethylene (HDPE) composites with and without coupling agent (3 % of maleated polyethylene (MAPE)) were manufactured by twin-screw extrusion followed by injection molding with high percentages of DPS (0, 20, 30 and 40 %). The effects of DPS content and MAPE on the mechanical, thermal, and morphological properties of the DPS/HDPE composites were investigated. Increasing DPS content in composites increased the tensile and flexural modulus (E; MOE), tensile and flexural strength (Rm; MOR), while decreased elongation at break and Un-notched impact resistance due to a poor adhesion between the DPS and HDPE. The addition of DPS also improved the thermal stability and increased the composites crystallinity. High content of DPS (40 %) and 3 % MAPE achieved good interfacial adhesion between fibres of DPS and HDPE. Therefore, an increase is observed for Rm, MOR, ductility, and impact toughness.

Recent studies have demonstrated the potential of primary sludge (PS) as reinforcing fibers and secondary sludge (SS) as binder or co-binder in wood–plastic composites (WPC). A comparative study was conducted using paper mill sludge produced by three different pulping processes at two SS to PS ratios. The objectives were to determine the impact of PS and SS on the development of high density polyethylene (HDPE) WPC properties. Sludge produced by thermomechanical pulping (TMP), chemithermomechanical pulping (CTMP), and Kraft pulping were used at three different proportions (20%, 30%, and 40%) for composite manufacturing. The use of mixed sludge containing 30% SS resulted in lower tensile, flexural, and impact performance of the WPC compared to mixed sludge containing only 10% SS for the three pulping processes. Sludge type had a significant impact on the WPC physical and mechanical properties. Kraft sludge produced the best WPC properties, followed by CTMP and TMP sludge. Increasing the sludge proportion produced increasingly negative impacts on water absorption and thickness swelling, but improved the flexural and tensile properties.

This study assessed the potential of wood residues as fiber sources for wood-plastic composites (WPC) and examined the impact for intrinsic fiber properties on strength development. Sawmill sawdust, underused wood species, bark, composite panel, and pulp and paper sludge residues were sampled. Fibers were characterized for cellulose content, ash content, and fiber aspect ratio. WPC samples were formed by twin-screw extrusion compounding, followed by injection molding at three fiber proportions. WPC mechanical properties, water uptake, and water swelling increased with increasing fiber proportion, whereas tenacity decreased. WPC made with residues had lower mechanical and physical properties than those made with clean wood, with some exceptions. Kraft sludge produced one of the best WPC formulations in terms of thickness swell, water swelling, tensile strength, and impact energy. Deinking sludge produced the toughest and the most dimensionally stable WPC. Panel industry residues formed roughly similar WPC to those made with clean wood. Bark led to poorest WPC in terms of mechanical properties. High correlation coefficients were found between cellulose content, wood content, and all WPC properties except impact energy. However, the correlations between aspect ratio and the WPC were insignificant. © 2014 Copyright Taylor & Francis Group, LLC.

Wood–plastic composites (WPC) were produced with white birch pulp fibers of different aspect ratios (length-to-diameter), high-density polyethylene, and using two common processes: extrusion or injection molding. Three additive levels were also used: no additive, compatibility agent, and process lubricant. Fiber size was measured with an optical fiber quality analyzer. Tensile properties of WPC were measured and modeled as a function of fiber aspect ratio. Models were fitted to experimental values using the minimum sum of squared error method. A shift from the oriented fiber case (injection molding) to the randomly oriented fiber case (extrusion) was achieved using a fiber orientation factor. Fiber/matrix stress transfer increased with increasing fiber aspect ratio. Stress transfer was reduced with the use of process lubricant. Unexpectedly, the compatibility agent had the same effect. Fiber strength and stiffness contributions to the composite were lower than those of intrinsic fiber properties.

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.

Les particules de bois dans les composites bois-plastiques (CBP) se présentent généralement sous forme de farine de bois, caractérisées par un faible ratio longueur/diamètre (L/D). Ceci pour des raisons de disponibilité et pour la facilité avec laquelle la farine de bois s’intègre aux procédés de mise en forme du plastique. Or, la morphologie des fibres joue un rôle important dans la formation et dans le développement des propriétés des produits à base de fibres de bois, comme le papier et les panneaux de fibres. Il en est de même pour les composites renforcés de fibres synthétiques. Il y a cependant très peu d’information disponible en ce qui concerne le rôle de la taille des fibres dans les produits CBP. De plus, l’utilisation de fibres longues est problématique et demande plus d’efforts de recherche. Ainsi, l’objectif général de cette étude est de comprendre le rôle de la longueur des fibres dans le procédé de formation et dans le développement des propriétés des CBP.

Des fibres de pâte à papier chimico-thermomécanique (PCTM) de bouleau blanc ont été réduites mécaniquement en trois classes de longueur. Les classes mesurées à l’aide d’un analyseur de qualité de fibres (AQF) optique ont respectivement des longueurs de 0,196, 0,304 et 0,481 mm et des ratios L/D de 8,3, 13,0, 21,3. Les caractéristiques de couple du polyéthylène haute densité (PEHD) fondu pur et chargé de trois proportions massiques (20, 30, 40 %) des trois classes de fibre ont été étudiées à l’aide d’un rhéomètre à couple. Des CBP à 40 % en poids de fibres PCTM ont été fabriqués par extrusion selon neuf formulations (3 longueurs, 3 formulations chimiques) et par moulage par injection selon trois formulations (3 longueurs). Également, des fibres PCTM ont été utilisées comme additif dans une formulation typique de l’industrie des CBP à 58 % en poids de farine de pin. Les CBP ont été caractérisés en termes de propriétés physico-mécaniques. Enfin, des techniques de modélisation ont été utilisées afin de mieux comprendre le rôle des dimensions des fibres de bois dans le développement des propriétés mécaniques des CBP.

Les résultats montrent que les caractéristiques de couple du PEHD fondu chargé de fibres PCTM varient avec la proportion massique et avec la longueur des fibres. Ainsi, les paramètres de mise en forme doivent être ajustés en fonction de la taille des fibres. Les propriétés physico-mécaniques des CBP varient avec la longueur des fibres, le procédé de mise en forme et les additifs utilisés. Les propriétés mécaniques augmentent avec la taille des fibres tandis que la performance diminue lors des essais en immersion dans l'eau. L'homogénéité et la densité des CBP ne sont pas influencées par la longueur des fibres. L’utilisation de fibres PCTM comme additif dans une formulation de CBP à base de farine de pin augmente les propriétés mécaniques. Finalement, les modèles théoriques permettent d’expliquer les implications de la taille des fibres dans la résistance et la rigidité des CBP. Ils ont toutefois tendance à surestimer les effets observés lors des essais mécaniques © 2007 UQAC tous droits réservés.