Comparison of crystallization behavior of Trans-1,4-polyisoprene under different crystallization temperature, pressure and tension

摘要

The crystallization of trans-1,4-polyisoprene (TPI) was influenced by many factors, such as the processing temperature, pressure and stress. The crystallization of TPI prepared under different conditions (temperature, pressure and tension) was characterized by Fourier transform infrared spectroscopy (FTIR), polarizing light microscopy(POM)and X-ray diffraction(XRD). The experimental results showed that the absorption frequency and the intensity of the FTIR spectra were not influenced by Mooney viscosity of TPI, however, it deeply affected by the sample preparation methods. The spectrum of hot pressed films showed a combination of -form and -form crystals, while that of solution cast films showed the characteristic absorption bands of -form crystals and less -form crystals. Spherulites of TPI could be obtained at several different crystallization temperatures (45 degrees C, 18 degrees C and 9 degrees C), but the size of the spherulites decreased from 180m to 70m with the decrease of temperature from 45 degrees C and 9 degrees C. When the temperature of the specimen decreased at a uniform rate (1.5 degrees C/min), large size spherulites were obtained. With the increase of pressure, the spherulites were not perfect. XRD patterns of TPI revealed that both -form and -form crystals existed in stretched specimens. Part of the -form crystals transformed into -form crystals during the extension.