| Wood flour/PVC (WF/PVC) composites have the excellent characteristics combining wood and PVC, which is a new composite material prepared with waste wood fibers, PVC and appropriate aids by hot pressing process. The product fully reflects the effective use of renewable resources and recycling of petroleum products; It has a great significance for easing issues such as the current shortage of resources and environmental pollution.This paper explored the impact factors on interface compatibility of WF/PVC composite; and then, it used different modifications and painting process to improve water absorption. On the other hand, the mechanism of interface compatibility and water absorption was analysis by FTIR, SEM and other microscopic means; Subsequently, it proposed different halogen flame retardants compound and organic modified means to achieve the flame retardancy and mechanical properties on above basis.The main conclusions were as follows:(1) The study on interface compatibility of WF/PVC compositesBoth wood flour content and coupling agent had a greater impact on interface compatibility of WF/PVC composites, which were superior to wood flour particle size or maleic anhydride grafting agent by orthogonal analysis. It found that the tensile strength and impact strength would be decreased rapidly with the improvement of the wood flour content; Wood flour particle which was too larger or smaller was not conductive to the dispersion and properties of WF/PVC composites; The mechanical properties could be increased obviously after the treatment by the silane coupling agent of KH550 or titanate coupling agent of NXT201;From FTIR analysis it indicated that the polarity of wood fiber weakened and the interface compatibility of plastic and non-polar substances enhanced; The results by SEM showed that the fuzzy interface between the matrix appeared continuous, isotropic and no flour reunion phenomenon after the treatment by modifiers, and interface compatibility had been improved significantly.(2) The research on water absorption of WF/PVC compositesThe experimental results indicated that water absorption and swelling in the thick direction of WF/PVC composite at 24 hour had increased with the content and particle size of wood flour. WF/PVC composite showed smaller water absorption with modifiers adding in a certain concentration range, additional coupling amount was not significant improvement in the production and would inevitably increase the cost of raw material; While, the treatment of surface painting could reduce water absorbency obviously; From FTIR analysis, it found that hydroxyl groups of water absorption peak and the polar of wood flour became weaken by the modifier treatments, indicating that water absorbency of WF/PVC composite had improved with the number of hydroxyl groups reducing; the specimens had well dispersion, fuzzy interface and no reunion phenomenon among the matrix phases by the technology of SEM, and further verified the above conclusions.(3) The study on the flame retardancy of WF/PVC compositeThe objective that had double well results between flame retardancy and mechanical properties was achieved through organic zinc borate, or organic bentonite compounded with ATH respectively. Especially, the former system better on the overall performance of the composites, which with the organic zinc borate of 15 portion and ATH of 5 portion had limiting oxygen index of 26.8%, tensile strength of 14.80 Mpa and izod impact of 19.42 KJ/m2; By weight analysis of TG and DTG, The results showed that, the mechanical properties of WF/PVC composite had improved with the flame retardants compounded, but the initial decomposition temperature lead to reduce. At the heat loss in weight of 50%, the corresponding temperature of decomposition delayed nearly 200 compared with no retardants compounded, thus the flame retardancy was greatly improved. |
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