Study On The Synthesis Of Silicon-contained Aromatic Hyperbranched Polyester And The Properties

In recent decade, hyperbranched polymers have been extensively studied because of its high branched structure with unique physical and chemistry characteristics.Hyperbranched polymers can be widely modified, because it contains a large number of end groups which are mostly reactive. Hyperbranched polymers have low viscosity and high solubility which make it has good application prospects in polymer materials. As one of the most important members of hyperbranched polymers, the synthesis process of hyperbranched polyesters are mature, and hyperbranched polyesters have important application in many fields, such as drug carrier, carrier gene, molecular recognition, polymer blends, resins and coatings. In this paper, a series of hyperbranched polyesters which contain organic silicon repeating unit were synthesized with trimellitic anhydride and dimethyl dimethoxy silane as monomers, the plasticizing effect of these hyperbranched polyesters to PVC were also investigated.Hyperbranched polyesters were synthesized by the intermediate of AB2 which were synthesized by trimellitic anhydride and dimethyl dimethoxy silane. A series of hyperbranched polyesters were synthesized with different ratio of monomers and The resuits showed that tetrahydrofuran(THF) is good solvent for hyperbranched polyesters and that methanol is poor solvent. The crude products were purified by the character of the difference in solubility between tetrahydrofuran and methanol.The structure of hyperbranched polyesters were characterized by FTIR and 1H-NMR and calculated the degree of branching(DB) of hyperbranched polyesterss by1H-NMR. The molecular weight and molecular weight distribution of hyperbranched polyesters were characterized by gel permeation chromatography(GPC). The glass transition temperature of hyperbranched polyesters were characterized by differential scanning calorimetry(DSC) method. Thermal degradation performance of hyperbranched polyesters were characterized by thermo-gravimetric analysis(TGA). HBPE-A, HBPE-B and HBPE-C were the products which were prepared at the rates of trimellitic anhydride and dimethyl dimethoxy silane were 1:1, 1:1.1and 1:1.2, respectively. HBPE-B which had the highest molecular weight, the narrowest molecular weight distribution, the highest DB, the lowest glass transition temperature and the best heat resistance during the three products were the best one to be studied about the plasticizing effect to PVC.DOP which is the small molecule plasticizers of PVC and DOP/HBPE which is a composite plasticizer were used to be compared the plasticizing effect to PVC withHBPE-B. PVC that contained different types and amounts of plasticizer were characterized by tensile test, impact test, Shore hardness and DSC. The results showed that HBPE were the best plasticizer to PVC when the amount of plasticizer less than 30% and the worst one when the amount more than 40% during the three plasticizer. The volatility test and liquid phase extractability test showed that there were no migration when HBPE were used as plasticizer in PVC.