Abstract
If we can gain better understanding about the chain arrangement of component monomers in EPDM molecule, especially the long chain sequence of ethylene, it will add to the basic knowledge of the crystallinity of ethylene in EPDM that dictates the processability of EPDM raw rubber. For the purpose of this study, we have selected EPM, ethylene•butene-1 copolymer and ethylene•4-methylpentene-1 copolymer as model compounds which are prepared by using various Ziegler-type catalyst.
These model compounds were analyzed by 13C-NMR spectrometer to investigate the arrangement of ethylene in the copolymers. In this study, we have developed here a new concept of“block methylene average length (BMAL)”and studied its relationship to the crystallinity obtained by X-ray study and to the physical properties such as tensile strength of the raw rubber.
As the results, (1) The value of BMAL is found to be proportional to the degree of ethylene content, and it differs from the kind of used catalyst. (2) There are some relationships between crystallinity and BMAL for each copolymer. (3) The relationships between crystallinity and tensile strength of copolymers are also proportional. Additionaly, assignment of the 13C-NMR spectrum of the ethylene•4-methylpentene-1 copolymer has been reported.
