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Natural fiber plastic composites were made from Nigerian grown bamboo (Bambusa vulgaris) and high density polyethylene by extrusion and evaluated for strength, sorption and thermal properties. Composites were manufactured using two different screened bamboo particle size fractions (<2 mm and < 0,5 mm). The composites were tested for flexural properties, water sorption, melt flow and thermal properties. The melt viscosities at 190oC were 22,3 ± 0,91 kPa·s (<2 mm) and 27,4 ± 1,2 kPa·s (<0,5 mm). The results obtained indicated that the composites made with the smaller particle size fraction had higher flexural strength (37,4 ± 1,0 MPa) and modulus of elasticity (2,0 ± 0,2 GPa) than those made with the larger particle size fraction (29,9 ± 1,1 MPa and 1,7 ± 0,1 GPa). Dynamic mechanical analysis also showed higher dynamic storage modulus for the <0,5 mm particle-based composites than those made from the <2 mm particle size fraction due to higher density and better interfacial interaction between the fiber and matrix. Also, the composites made with the smaller particles and were more dimensionally stable (water absorption of 5,4% versus 18,5% at 61 d). The bamboo composites had thermal stability range of 265 - 279oC (onset degradation temperature). The composites made with the smaller bamboo particles possessed the better properties in comparison with those made from the <2 mm. Particle size and density significantly affected the mechanical, physical, thermal and rheological properties of the composites evaluated. [ABSTRACT FROM AUTHOR]

The feasibility of using rattan canes (Laccosperma secundiflorum and Eremospatha macrocarpa) as reinforced fillers for high density polyethylene based plastic composite production was investigated. Extruded composites were tested for water sorption, tensile and thermal properties. The results obtained indicated that the rattan composites were dimensionally (water absorption: 2,2-21,4% thickness swell: 0,9-5,3%) and thermally stable (Tc: 116,8-118,2°C) and possessed adequate tensile properties (7,3-21,7 MPa). Composites made from L. secundiflorum had higher strength and thermal properties but lower sorption values compared to those of E. macrocarpa. Differences in the densities of the composites and the anatomical structures of the rattans seemed to influence properties of the composites. [ABSTRACT FROM AUTHOR]

Effects of accelerated and natural weathering on the molecular weight distribution (MWD) and crystallinity of polypropylene (PP) in wood plastic composites (WPC) were investigated. The composites were produced from pine fibers (60%) and PP (40%). Prolonged weathering caused an increase in wood degradation and erosion thereby leaving cracks and "pits" on the surface. Pyrolysis gas chromatography-mass spectrometry (Py GC-MS) revealed that PP dominated the weathered surface due to wood degradation. For matrix analysis, PP was extracted using 1,2,4-trichlorobenzene. Crystallinity and molecular weight distribution of PP were monitored by differential scanning calorimetry (DSC) and gel permeation chromatography (GPC), respectively. PP's crystallinity increased upon longer exposure time. The weight and number average molecular weight (Mw and Mn) decreased with an increase in weathering duration. An increased polydispersity (PD = Mw/Mn) implies that a secondary cross-linking process occurred during weathering. [ABSTRACT FROM AUTHOR]

The popularity and demand for wood plastic composites (WPC) has focused research on fiber properties associated with performance. In this study, maple wood fibers (WF) were ball milled and classified into discrete size fractions. Fiber analyses showed only three distinct WF size classes (80-100, 100-200 and <200 mesh). High density polyethylene (HDPE) based WPC were made from classified WF (10 to 50%). The effect of WF size, loading, and maleated polyethylene (MAPE) coupling agent on WPC rheological behavior (torque rheometry and melt flow rate (MFR)) and flexural properties were examined. The WPC MFR decreased with wood loading, increased with a reduction in WF size. The modulus of rupture (MOR) was shown to increase with a reduction in WF size and increase with the addition of MAPE. The increase in MOR is likely due to an increase in the interfacial interaction between the polymer and WF. Modulus of elasticity (MOE) was shown to increase with an increase in wood loading and decrease with a decrease in WF size. The toughness of the WPC was shown to increase with a decrease in WF size and increase upon addition of MAPE. [ABSTRACT FROM AUTHOR]