Effects of Topological Constraint and Knot Entanglement on the Crystal Growth of Polymers Proved by Growth Rate of Spherulite of Cyclic Polyethylene

In order to clarify the effects of entanglement species on nucleation of polymers, we studied the growth rate of spherulite G of cyclic and linear polyethylenes (C-PE and L-PE) from the melt as a function of degree of supercooling Delta T by means of polarizing optical microscope. We prepared several C-PEs with different weight average molecular weights My, 9300, 43600 and 86500, and L-PE with M(w) = 44000. G of all the sample were obeyed the equation, G = G(0) exp (-B/Delta T). B of C-PE gradually increased with increasing M(w). B is proportional to the surface free energy of the end surface of the nucleus, and this indicates that the regularity of folding surface increased with increasing M(w). We consider that topological constraint of cyclic polymer becomes large with decreasing M(w) of the cyclic polymer. On the other hand, for C-PE and L-PE having almost the same M(w) (=44 k), C(0) of C-PE is much less than that of L-PE. Due to the topological constraint of cyclic polymer, we speculated that the adsorption mode on the crystal surface of C-PE is different than that of L-PE.