Abstract
Physicochemical and mechanical properties of crystalline polypentene-1 and its copolymer with 3-methyl-1-butene were studied. The Form II, one of the two crystalline modifications of polypentene-1 was stable at room temperature and transformed gradually to another modification, Form I, by annealing at temperature range from 50°C to 80°C.
Though mechanical properties of films or fibers of the both crystalline forms are affected by the degree of crystallinity, there is no essential difference in the tensile properties. It was found that copolymer of pentene-1 with 3-methyl-1-butene can cocrystallize in the Form II of polypentene-1 over the whole range of composition, and their melting points change continuously from 80°C of polypentene-1 to 300°C of poly(3-methyl-1-butene) according to the composition.
Although the crystalline copolymer of pentene-1 with minor 3-methyl-1-butene composition has almost the same poor tensile properties as pentene-1 homopolymer, the melting point of polypentene-1 increases by the copolymerization.
It is also recognized that the copolymerization of major 3-methyl-1-butene with pentene-1 is effective to decrease the characteristic brittleness of poly (3-methyl-1-butene).
