Test Technology And Application Research On Pvt Relationship Of Polymers

The equation of state is used to describe PVT (pressure-volume-temperature) relationship of polymers. It has significant meanings to compute the specific volume at different pressure and temperature and research the blend of polymers. Meanwhile, the PVT datas support the development of equation of state of polymers. The PVT relationship of polymer is a significant basis for flow analysis of injection molding, simulation of warpage and shrinkage deformation. It is also the main method to test material parameters such as the isothermal compression coefficient, thermal expasion coefficient and thermal pressure coefficient. Therefore, the PVT test and relative research have important meanings.Firstly, the development of equation of state of polymers and relative testing technologies were summarized and concluded. By investigating and studying literatures, the application range and the deficiency of equation of state were acknowledged. The principle of PVT testing technology and respective advantages and disadvantages were understood.Secondly, the testing work of nine kinds of polymers about the crystalline polymers and amorphous polymers were finished, and influence factors of test results such as the air bubble, the wall bonding and the melt fluid were solved. Meanwhile, PVT testing parameters such as the temperature, the compression rate and the sampling time was obtained. The testing PVT datas appeard very regular.Thirdly, The PVT datas of nine kinds of polymer melts were predicted with the group contribution modified cell mold (GCMCM). The results showed that the predicted curves wholly moved up slightly. Meanwhile, the datas were also predicted with the cell mold (CM), the characteristic parameters were computed and the PVT curves from15MPa to45MPa were predicted, the results showed that the predicted results were consistent to the real datas.At last, the threee kinds of amorphous polymers, PC(Makrolon2805), PS(PG-33) and PMMA(CP51A) were analysed with the theory of Simh-Boyer. The affection of temperature and pressure to free volume fraction were discussed. Meanwhile, the viscosity of PMMA(CP51A) was tested and PVT characteristic parameters of Tait were fitted. The shrinkage fraction of the length direction and width direction was simulated and compared to the measured results.