螺旋构象 全同聚丙烯 MH MH MH MH MH MH M CH; 0.4nm 每3个CH2-CH.转一周 CH3 =CH3,-C2H5,-CH=CH2,-OCH3 记作31或2x3/1 螺旋构象 全同聚丙烯 0.4nm CH3 C C C C C C C C C C C C C C H H M H M H M H M H M H M H M M M M M M M M 每3个-CH2-CH- 转一周 CH3 记作31或23/1 H H H H H H =CH3 , C2H5 , -CH=CH2 , OCH3