James S. Fabiyi

Degradation of polypropylene in naturally and artificially weathered plastic matrix composites

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.

Weathering performance of delignified pine-based polyvinyl chloride composites

The influence of pine fiber treatments on the color and chemical changes of polyvinyl chloride-based wood plastic composites exposed to outside and xenon-arc accelerated weathering was investigated. The wood plastic composites were produced from pine fiber (untreated control, acetone extracted, and holocellulose (delignified)) and polyvinyl chloride. Different analytical tools (colorimetry, microscopy, infrared spectroscopy, and gel permeation chromatography) were employed for weathered wood plastic composites characterization. The study showed that longer exposure time in both outside and accelerated weathering regimes caused an increase in color change and lightness, cracking, higher oxidation but decrease in wood (lignin) content of the weathered wood plastic composites’ surface for all the wood fiber types. The polyvinyl chloride molecular weight decreased with increase in exposure time of the composites. From this study, delignified wood fiber-based wood plastic composites had less color (lightness) change and reduced surface cracking with lowest weathered surface oxidation. Furthermore, relationships between accelerated and outside weathered wood plastic composite surfaces were observed.

Infrared Spectroscopy Studies of Ricinodendron heudelotii Wood for its Pulp and Paper Production Potential

The high demand for paper production due to its various uses, but the dwindling of forest trees as a result of deforestation and forest exploitation necessitate the investigation of Ricinodendron heudelotii, a lesser utilised tree species for its pulp and paper production potential. In addition, any technique for such investigation that would give reliable but fast information is encouraged. Therefore, infrared spectroscopy was employed to study the chemical components of R. heudelotii wood since chemical component. Ratios of syringyl to guaiacyl associated bands along the longitudinal and radial positions of the wood differ significantly. Higher syringyl/guaiacyl ratio of the corewood than middlewood was observed. The practical implication of this finding is that more chemical would be required to pulp R. heudelotii wood obtained from the base (10% of the merchantable height) and outerwood, because of the presence of high lignin content compared to the other longitudinal (middle, 50% and top, 90% of the merchantable height) and radial (corewood and middlewood) positions where wood were collected. Also, outerwood favour pulp production compared to middlewood and corewood, because of the high holocellulose content.