Study On Preparation And Thermal Stability Of Poly(Propylene Carbonate)/Attapulgite Composites

With the rapid development of industry, we now have suffered much from theenvironment crisis of "greenhouse effect" and "white pollution". Poly（propylenecarbonate）（PPC） derived from the copolymerization of CO2and propylene oxide is abiodegradable polymer material. The complete biodegradability and low cost of PPCmake it potentially suitable for replacing universal plastics to reduce the amount ofpolyolefin waste. However, the weak carbonate linkage in the backbone and thenoncrystallization of PPC lead to its relatively low glass transition temperature, lowthermal decomposition temperature and poor mechanical properties, limiting thepractical applications of this copolymer. Modification of blending is the mosteffective measure to improve the performance of PPC. Attapulgite （AT） with nanocrystals structure show high thermal stability and mechanical strength. Therefore,PPC/AT composites were prepared via solution blending by three different ways inthis article. Thermal performances of PPC/AT composites were investigated in detail.PartⅠ:Poly（Propylene carbonate）/attapulgite composites were prepared via solutionblending with PPC and attapulgite treated by hydrochloric acid or roasting methods.The results showed that the thermal stability of PPC were enchenced by attapulgitetreated by450℃roasting method. That is, PPC/attapulgite composites exhibiteddramatically improved thermal properties compared with PPC. PPC/attapulgitecomposites with4wt%AT indicated the highest thermal stability. The T_10% and T_maxof composites are259℃and279℃, which are higher than pure PPC s34℃and42℃,respectively.PartⅡ:PPC/OAT nanocomposites were prepared successfully via solution blending withPPC and OAT modified by cetrimonium bromide through cation exchange method.The thermal properties and thermal decomposition dynamics of nanocomposites werestudied in detail. The thermal stability of PPC can be effectively increased by theintroduction of OAT. PPC/OAT nanocomposites with0.5wt%AT exhibited the highest thermal performance. T10%and Tmaxof nanocomposites are280℃and289℃,which are higher than pure PPC’s55℃and52℃, respectively. Research on thethermal decomposition dynamics of PPC/OAT nanocomposite revealed that themechanism of PPC/OAT thermal decomposition is close to [-ln（1-α）]^1/4, followed therandom nucleation and subsequent growth mechanism.PartⅢ:PPC/MDI-AT composites were prepared from PPC, Toluene-4,4-diisocyanate andattapulgite. Diisocyanate plays an important role in solution blending of PPC and ATdue to the high reactivity to hydroxyl groups. The reactions between PPC, MDI andAT ensure the percolation network structure of composites, which were confirmed byFT-IR and SEM techniques.The thermal stability of percolation network compositeswas studied by thermogravimetric analysis （TGA）, the results showed that thepercolation network composites exhibited higher thermal performance.