反式-1,4-聚异戊二烯的结晶性

采用差示扫描量热仪、傅里叶变换红外光谱、偏光显微镜和X射线衍射仪等研究了反式-1,4-聚异戊二烯(TPI)的结晶性。结果表明,在TPI的差示扫描量热分析中,随着升温速率提高,第1次升温曲线上的β晶型熔融温度移向高温;而第2次升温曲线上的α晶型结晶熔融峰逐渐消失,且与第1次升温时相比β晶型的熔融温度偏高;而随着降温速率的提高,TPI的结晶峰向低温方向位移。用不同方法制备的TPI薄膜可以得到球晶、碎晶和捆束状晶体。与浇铸薄膜相比,热压薄膜傅里叶变换红外光谱曲线上的843 cm-1和980 cm-1两侧各出现了2个肩峰,而890 cm-1处的结晶峰消失。拉伸后在TPI的X射线衍射谱线上,0.47 nm和0.39 nm晶面间距的所属峰形比拉伸前要尖锐得多,而0.33 nm晶面间距所属峰则弱化。

Crystallinity of trans-1,4-polyisoprene

The crystallinity of trans-1,4-polyisoprene(TPI) was characterized by differential scanning calorimetry(DSC),Fourier transform infrared spectroscopy(FTIR),polarized light microscopy and X-ray diffraction(XRD).The results showed that with the increase of heating rate,the melting temperature of β-crystal in the first heating DSC curves of TPI shifted towards higher temperature,while the crystalline melting peak of α-crystal gradually disappeared in the second heating curves.Compared with the first heating curves,melting temperature of β-crystal was slightly higher.TPI crystalline peak shifted to lower temperature with increasing the cooling rate.Spherulites,broken grain and bundle crystal could be obtained from TPI films prepared by different methods.Compared with the cast film,there were two shoulder peaks on each side of 843 cm-1 and 980 cm-1 absorption bands,while crystalline peak at 890 cm-1 disappeared in the FTIR curve of hot-pressed TPI film.Crystalline peaks corresponding to 0.47 nm and 0.39 nm interplanar spacing were much sharper than those before stretching,while the peak corresponding to 0.33 nm interplanar spacing weakened in the XRD pattern of TPI after stretching.