Conclusions
Chitosan with various addition amounts and particle sizes were incorporated into WF/PVC composites as a novel biopolymer coupling agent. Functional amino-groups in the molecular chains of natural chitosan were indirectly verified to engender a “bridge” link between wood flour and PVC matrix by the thermal analyses of VST, DSC and TGA. An optimum addition amount (30 phr) with the particle size (180–220 mesh) could elevate heat resistance capacity, glass transition temperature of composites as well as thermal stability at the early stage of degradation more effectively. Compared to WF/PVC/SA composites added 5 phr silane coupling agent, the heat resistance capacity and thermal stability at the early stage of degradation of WF/PVC/CS clearly performed better while the thermal stability of the whole compound system was showed to be a little weaker.
As for the rheological characteristics, longer fusion time, lower fusion torque and higher fusion temperature were mainly attributed to the lower bulk density and higher heat capacity of compounds at higher addition level of CS as well as lower frictional forces and heat by shearing at smaller particle size level of CS. The three variation trends obviously slid when the addition amount of CS was beyond 30 phr. It was worthy to note that the torque rapidly decreased to approximately zero after passing the stable processing stage when the addition amount of CS exceeded 20 phr, the whole compound system needed to be supplied a higher pressure to maintain a sufficient compaction and ensure proper blending during extrusion. Oppositely there was almost no variation in the stable processing time despite the various particle sizes of CS
ConclusionsChitosan with various addition amounts and particle sizes were incorporated into WF/PVC composites as a novel biopolymer coupling agent. Functional amino-groups in the molecular chains of natural chitosan were indirectly verified to engender a “bridge” link between wood flour and PVC matrix by the thermal analyses of VST, DSC and TGA. An optimum addition amount (30 phr) with the particle size (180–220 mesh) could elevate heat resistance capacity, glass transition temperature of composites as well as thermal stability at the early stage of degradation more effectively. Compared to WF/PVC/SA composites added 5 phr silane coupling agent, the heat resistance capacity and thermal stability at the early stage of degradation of WF/PVC/CS clearly performed better while the thermal stability of the whole compound system was showed to be a little weaker.As for the rheological characteristics, longer fusion time, lower fusion torque and higher fusion temperature were mainly attributed to the lower bulk density and higher heat capacity of compounds at higher addition level of CS as well as lower frictional forces and heat by shearing at smaller particle size level of CS. The three variation trends obviously slid when the addition amount of CS was beyond 30 phr. It was worthy to note that the torque rapidly decreased to approximately zero after passing the stable processing stage when the addition amount of CS exceeded 20 phr, the whole compound system needed to be supplied a higher pressure to maintain a sufficient compaction and ensure proper blending during extrusion. Oppositely there was almost no variation in the stable processing time despite the various particle sizes of CS
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