Nature rubber is one kind of significant material that plays an important role in modern life. High elasticity, which is closely related with its structure, is the primary character of nature rubber. Doing research on the relationship between its structure and function will have contributed not only to its application but also to research and development of more excellent products.In the fifteenth century, when America was discovered by Columbus, native Americans made use of nature rubber. Nature rubber is easily becoming soft and sticky, which prevent it widely used until sulfide cross-linking is found by Goodyear and it comes one kind of important industrial raw materials subsequently. Cross-linked structure of nature rubber produces a significant effect on the its performance of nature rubber, so the study on such structure is necessary.The structure of crystallization is also very important besides crosslinking. Crystallization is easily formed during the procession of stretching, and the recent research are also concentrated in the stretching crystallization. There is a small amount of crystalline in unstretched rubber at room temperature. Then we do some research on this phenomenon with DSC and NMR methods. |