Study On The Modification Of Thermoplastic Polyurethane And Polyvinyl Chloride Blends

Thermoplastic polyurethane (TPU) is one of the most versatile engineeringthermoplastics with elastomeric properties. TPU possesses higher tensile modulus,higher abrasion resistance, and resistance to oil and many solvents in comparison withrubber. However, TPU is limited in its application in several technologically importantfields due to its high product cost and some properties defects. Polyvinyl chloride(PVC) is generally used to be blended with TPU to modify the latter one and decreasethe cost. In this work, binary blending elastomer with TPU and PVC, and ternary blendingelastomer with TPU, PVC and some other polymer are studied. The mechanicalproperties, rheological properties, resistance to oil and solvent properties andelectrical properties of these two kinds of blends are investigated. Through blending,it is expected to obtain a new polymer material with excellent propertied and low cost.Thermal stability of TPU/PVC blends is another part of this research. Congo red testis mainly used to study mechanisms of dehydrochlorination of TPU/PVC blends. Andthe effect of lead salt stabilizer or organic tin stabilizer incorporated into TPU/PVC isalso quantified by Congo red test. The results of the Congo red tests indicate that TPU has an important effect onthe dehydrochlorination of the TPU/PVC blends, while thermal stabilizers play anefficient role in improving the heat stability of TPU/PVC blends. TPU not only dilutesPVC to reduce the concentration of HCl emitted from PVC, but also acts with HCl, sothat it accelerate dehydrochlorination of TPU/PVC blends. Accordingly it can enhancethe thermal stability of PVC. In chosen three organic tin thermal stabilizers, the effectof mercaptide organic tin (395A and T-137) is better than that of DBTL. There is asynergistic action in DBTL mixed with epoxidized soybean oil or calcium stearate,which is showed by restraining dehydrochlorination of PVC. Owning to the effect ofTPU, thermal stability of TPU/PVC blends is not improved with the content of leadsalt thermal stabilizers increases, while that of plasticized PVC system becomes better IIIAbstractwith an increasing lead salt thermal stabilizers concentration. Thermal stability ofTPU/PVC system with dibasic lead phosphite is better than that of TPU/PVC systemwith two other lead salt thermal stabilizers under the same condition. The mass ratioof dibasic lead phosphite to tribasic lead sulphate is 1 to 3, which is the best one inrestraining dehydrochlorination of TPU/PVC system. Binary blend of TPU/PVC is mixed by mechanical method. It is clear thatmechanical properties of TPU/PVC blends are better than those of each individualpolymer. Cooperative effects are also showed on oil and solvent resistance properties.When the mass ratio of TPU/PVC is 90/10, the general mechanical properties of theblend are the best. The blend with the ratio of 70/30 is just inferior to 90/10.Considering the product cost and mechanical properties, TPU/PVC with mass ratio70/30 is chosen as the basic proportion to study in application. As the content ofplasticizer dioctyl phthalate (DOP) increases in TPU/PVC blends, the mechanicalproperties of the blends decrease. 395A as the organic tin stabilizer acts best when it is3 phr added to the TPU/PVC blends (PVC 100 phr). Silica is better than other chosenfillers. But if silica is added more than 15 phr to the TPU/PVC blends, the mechanicalproperties of the blends decrease sharply. Furthermore, the scanning electronmicroscopy (SEM) micrographs show that the ratio of 70/30 is more compatible thanother ratios, which is consistent with the results of mechanical properties tests.Differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA)demonstrate that the thermal stability of TPU/PVC blend is improved by mixing TPU. In the study of ternary blending, TPU/PVC blend with mass ratio of 70/30 is stillchosen as the basic proportion. And severa...