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Direct Evidence of Nucleation During the Induction Period of Polyethylene Crystallization by SAXS

2003; Taylor & Francis; Volume: 42; Issue: 3-4 Linguagem: Inglês

10.1081/mb-120021610

1525-609X

Masamichi Hikosaka, Shinichi Yamazaki, Isao Wataoka, Narayan Chandra Das, Kiyoka Okada, Akihiko Toda, Katsuaki Inoue,

Fiber-reinforced polymer composites

Abstract Direct evidence that nuclei are formed during the induction period of crystallization is obtained for the first time by means of small-angle X-ray scattering (SAXS). Polyethylene (PE) was used as a model crystalline polymer. The nucleating agent was mixed with PE in order to increase the scattering intensity I x from nuclei as large as 104 times bigger than usual. I x increased soon after quenching to the crystallization temperature from the melt and saturated after some time. A new theory is proposed to estimate the size of the nuclei N, the number density distribution of nuclei with N at time t, f(t,N), and the induction time τ i, by analyzing the SAXS scattering intensity. The volume-averaged size of the nuclei was nearly the same as that of critical nuclei and does not change so much with time during the induction period. Lamellae start stacking much later than nuclei start forming. Keywords: Induction periodNucleationDegree of supercoolingPolyethyleneSmall-angle X-ray scatteringNucleus Acknowledgment The authors are grateful to Asahi Denka Kogyo K.K for supplying the nucleating agent, NA-11SF, and to Mr. Motoki Arakaki of Hiroshima University for his help in experiments and analyses. The authors also thank Dr. Zdenek Kozisek of Institute of Physics, Academy of Sciences of the Czech Republic, for his helpful discussions. This work was partly supported by Grant-in-Aid for Scientific Research on Priority Areas B2 (No.12127205) and Scientific Research A2 (No.12305062). The authors are also grateful to SPring8 (SP8) at JASRI in Harima and Photon Factory (PF) at KEK in Tsukuba for supporting this SAXS experiment.