Wood particle filled polyvinyl chloride composites and their foams

Extruded composite compositions of PVC and wood particles containing chitosan or chitin as a coupling agent are described. The composite compositions have improved physical and mechanical properties.https://digitalcommons.mtu.edu/patents/1029/thumbnail.jp

Photodegradation of polystyrene/montmorillonite clay: the effect of the type of clay and presence of salt

Compósitos de poliestireno/montmorilonita (PS/MMT) contendo 2,5% em peso de argila foram preparados com dois tipos de argila modificada com sais quaternários de amônio. Também foram preparadas amostras do PS + sal quaternário de amônio, utilizando-se proporção de sal semelhante à usada na modificação da argila. Todas as amostras foram expostas à radiação UV por períodos de até 12 semanas, e em seguida foram realizados testes para avaliar as modificações em massa molar, propriedades mecânicas (tração e impacto), estrutura química (FTIR) e superfície de fratura (MEV) dessas amostras. Os resultados mostraram que compostos metálicos existentes na argila catalisam o processo fotodegradativo do PS e a presença isolada do sal não altera significativamente o comportamento do PS frente à radiação UV

Aging mechanisms in cellulose fiber reinforced cement composites

This paper examines the effects of laboratory scale accelerated aging exposures on the changes in physical and mechanical properties of commercially produced cellulose fiber reinforced cement composites. Two different accelerated aging methods were used to simulate the possible aging mechanisms for which the material may experience under service conditions, both methods being compared to material naturally weathered for 5 yr in roofing. The first aging method consisted of different cycles of water immersion, carbonation, and heating exposures whereas in the second method, cycles of water immersion, heating and freeze-thaw exposures were used. The porosity, water absorption, permeability of nitrogen and compressive shear strength of the composites were examined before and after aging exposures. The surface morphologies of the composites fractured in compression shear tests were examined using scanning electron microscope. Experimental results showed that the compressive shear strength of the accelerated aged composites were related to the microstructures within the composites. Both natural weathering and accelerated aging in CO2 environment reduced the porosity, water absorption, and nitrogen permeability in the cement matrix, and enhanced the durability of the cellulose fiber-cement composites. The aging test based on artificial carbonation was more effective in simulating natural aging performance of the composites, while the freeze-thaw cycling method failed to induce significant aging effects on the composites even after 21 cycles

Novel coupling agents for PVC/wood-flour composites

Effective interfacial adhesion between wood fibers and plastics is crucial for both the processing and ultimate performance of wood-plastic composites. Coupling agents are added to wood-plastic composites to promote adhesion between the hydrophilic wood surface and hydrophobic polymer matrix, but to date no coupling agent has been reported for PVC/wood-fiber composites that significantly improved their performance and was also cost-effective. This article presents the results of a study using chitin and chitosan, two natural polymers, as novel coupling agents for PVC/wood-flour composites. Addition of chitin and chitosan coupling agents to PVC/wood-flour composites increased their flexural strength by ∼20%, their flexural modulus by ∼16%, and their storage modulus by ∼33-74% compared to PVC/wood-flour composite without the coupling agent. Significant improvement in composite performance was attained with 0.5 wt% of chitosan and when 6.67 wt% of chitin was used.-© 2005 Society of Plastics Engineers

Efficient one-pot synthesis and loading of self-assembled amphiphilic chitosan nanoparticles for low-leaching wood preservation

A simple, one-step and one-pot method was used to synthesize amphiphilic self-assembling chitosan-g-PMMA nanoparticles (∼100 nm diameter by SEM, but ∼150-200 nm in water by DLS), containing ∼25-28 wt.% (∼82-93% capture efficiency) of the fungicide tebuconazole. The matrix composition was selected to be environmentally low impact, while the nanoparticle preparation conditions were designed to ensure the nanoparticles were sufficiently small to be able to penetrate the pit pairs of solid wood. These nanoparticles were delivered into southern pine sapwood blocks at target fungicide retentions of 0.2, 0.4 and 0.8 kg tebuconazole/m3wood. SEM analysis of a 19 mm × 19 mm × 455 mm nanoparticle-treated wooden stake confirmed penetration throughout the interior of the treated stake. Leaching studies confirmed that biocide introduced into sapwood via nanoparticle carriers leached only about 9% as much fungicide as solution-treated controls, while soil jar tests showed the nanoparticle-treated wood blocks effectively protected the wood from biological decay when tested against G. trabeum, a brown rot fungus. © 2011 Elsevier Ltd All rights reserved