| Poly (vinyl chloride), one of the five general synthetic resins in the world, was widely applied in all areas of people's lives for its excellent performance and lower cost. But PVC materials were weaked in stability, which can lead to surface color change and mechanical properties losses. Its main reasons were UV light, heat, water and air pollution, and UV light will be accounted for a dominate position. In this paper, the effects, caused by inorganic particles and UV absorbent, of PVC materials aging properties were studied. The main results can be concluded as follows:CaCO3 was modified by a macromolecule (MP) synthesized in our lab, and the product was characterized by FT-IR and SEM. FT-IR showed that CaCO3 was coated by MP, and its aragonite structure didn't disappear. SEM indicated that modified CaCO3 showed a better dispersion, and no significant agglomeration.PVC/inorganic particle composites (PVC/SiO2, PVC/CaCO3, PVC/CaCO3@MP) were prepared by melt blend with PVC and different inorganic particles (SiO2, CaCO3, CaC03@MP), and their mechanical and UV aging properties were investigated. a) Mechanical properties showed that inorganic particles had no effect on PVC materials'tensile strength, but obviously improved the materials'notched impact strength and elongation at break. CaCO3@MP was the best flexibilizer of the three inorganical particles, compared with neat PVC material, the biggest increase rate of PVC/CaCO3@MP composite's notched impact strength was 19.29%, which was better than PVC/SiO2, its best increase rate is 9.23%, and PVC/CaCO3, its best increase rate is 16.09%.b) UV aging properties indicated that inorganic particles can improve PVC materials'UV light stability. Compared with neat PVC, irradiation time D1 of PVC/CaCO3 and PVC/CaCO3@MP composites was increased by 63.92% and 77.41%, while irradiation time D2 was increased by 62.71% and 64.62%, when the weight fraction of CaCO3 and CaCO3@MP were both 16 phr. c) Inorganic particles, UV light stabilizers, can inhibit the aging of PVC chain segments and alleviate the increasement of double bone index, caused by UV light.PVC/UVA composite was prepared and its aging properties were investigated. Apparent color, FT-IR and UV-vis showed that the UV light stability of PVC composite improved after the UV absorbent added in. Compared with neat PVC, when the fraction of UVA was 0.4 phr, irradiation time D1 and D2 increased 86.16% and 72.41%, respectively. Mass loss, FT-IR and DSC demonstrated that UVA can inhibit the fracture of PVC chain segments and promote the crosslinking reaction of activity macromolecular chain, lead to its UV light stability effect.UV irradiation activation energies of PVC composites were calculated by apparent color changing in continuous irradiation times with different aging temperatures. The activation energies of PVC/inorganic particle composites were lower than that of PVC material, and the activation energy changing trends in different reaction stages changed, which indicated that inorganic particles can improve the thermal stability and change the stage mechanism of PVC UV photo aging. The activation energy of PVC/UVA composite was higher than PVC material, and their changing trend in different reaction stages were similar, which demonstrated that UVA made the thermal stability weaker but held the stage mechanism of PVC UV photo-aging. |
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