Application Research Of Poly (Propylene Carbonate) For Film Products

Poly(propylene carbonate)(PPC)materials were expected to used into real lives for its perfect properties,such as good mechanical property,excellent gas barrier property and characteristic biological degradability.However,PPC couldn't be used as extensive as the traditional materials due to its lower glass transition temperature(Tg)and lower thermal decomposition temperature(Td).Therefore,to make up its defects,two methods were researched: chain-extending reaction and melt blending.Hexamethylene diisocyanate(HDI)trimer and Increasing precision with decreasing intelligence(IPDI)trimer were used as chain extenders.Poly(lactic acid)(PLA),poly(butylene adipate-co-terephthalate)(PBAT)and thermoplastic polyurethane elastomer(TPU)were melt with PPC.A series of research were carried out.The results were as follows:(1)Both Tg and Td of chain-extended PPC were clearly increased.Fourier transform infrared spectroscopy(FTIR)and nuclear magnetic resonance(1H-NMR)results were indicated that chain-extending reaction occurred between HDI trimer and PPC.Thermal gravimetric analyzer(TGA)results showed that the thermal stability of PPC could be improved by the addition of chain extenders.Especially,the temperature of 5% thermal weight loss(T-5%)were increased from 167 oC to 256 oC.(2)PPC/PBAT blends were prepared by melted blending.When PPC content was higher than 40wt%,there was no improvement for tensile strength and toughness of the blends.The chain extender content was varied in range of 1phr to 2phr in film products.Differential scanning calorimeter(DSC)results showed that the Tg of PPC tended to increase with increasing chain extender content.TGA examination indicated that the thermal stability of the blends was improved by the addition of chain extenders.Melt flow rate(MFR)results showed that the MFR of the blends was decreased with the increase of the chain extender content.The tensile strength of the blends was increased with increasing chain extender content.The elongation at break of the blends was increased non-apparent,changing in range of 500%~800%.The machine direction(MD)tensile strength of films was higher than the transverse direction(TD)tensile strength.However,the TD tear strength of films was much greater than the MD tear strength.The degradation examination results showed that the degradation rate of PPC/PBAT blends was at a small value.The degradation rate could be varied enormously,depending on experimental methods.The values were about 0.4% whenthe films were buried in the soil for two months,and about 0.8% when the blends were dipped into lipase solution for a month.(3)The plasticized corn starch(P-CS)content had a great influence on the properties of the blends.Overall situation,the composites were blended with 20 phr P-CS.The content of the chain extenders changed from 2 phr to 4 phr.DSC results indicated that the degree of crystallization for PLA decreased with increasing chain extender content.TGA showed that the improvement of the thermal stability became non-apparent with increasing chain extender content.MFR results showed that the MFR values were decreased with increasing chain extender content,and increased with increasing P-CS content.When the P-CS was introduced into the blends,both the MD tensile strength and TD tensile strength for the films were increased with increasing chain extender content.Also,the TD tear strength was obviously increased.However,the improvement of MD tear strength showed non-apparent.Both water absorption and degradation rate were increased with increasing P-CS content.And scanning electron microscope(SEM)results showed that the starch was equably dispersed in the matrix with obvious interface.(4)For PPC/TPU blends without chain extenders,the mechanical properties were not increased due to the two-phase structure between PPC and TPU.The mechanical and thermal properties were increased by the addition of chain extender.The contents of chain extenders were varied in the range of 1 phr to 2 phr in films.Dynamic mechanical analysis(DMA)results showed that the storage module of the blends showed an increasing trend with increasing PPC content.Also,the storage module could be improved by the addition of Chain extender.TGA showed that the thermal stability of the PPC/TPU blends was enhanced with increasing chain extender content.DSC results showed that PPC and TPU were not crystal materials.With increasing chain extender content,the vicat softening temperature(VST)tended to increase,but the MFR values tended to decrease.For PPC/TPU films,the MD tensile strength was much higher than the TD tensile strength.However,the TD tear strength was higher than the MD tear strength.The thermal shrink rate for films was decreased with increasing chain extender content.More over,the MD thermal shrink rate was higher than that of the TD.