Crystallinity of poly(tetramethyl-p-silphenylenesiloxane) and (tetramethyl-p-silphenylenesiloxane)-(dimethyl siloxane) copolymers

An X-ray method is described for determining the degree of crystallinity of poly(tetramethyl-p-silphenylenesiloxane) (TMPS) homopolymers and copolymers of tetramethyl-p-silphenylenesiloxane (TMPS—DMS) of wt % TMPS—DMS ratio of $\text{48}\text{52}$, $\text{65}\text{35}$ and $\text{85}\text{15}$, respectively. The specimens had an average DMS block size of 30 monomeric units. Polymers ranging from 100 wt % TMPS to approximately 50 wt % of TMPS were studied. Over this composition range the crystallinities varied from 75 to 30% approximately. Crystallinity determinations were also made using a density gradient column and differential scanning calorimetric methods for comparison purposes to check the validity of the X-ray procedure described herein. The results of the three techniques were in satisfactory agreement although some refinements are still in order.