Effects of microtacticity on 1H and 13C magnetic relaxation times of isotactic polypropylene crystallized at high temperature

✍ Scribed by Hiroshi Tanaka; Yoshinori Inoue

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 307 KB
• Volume: 29
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(93)90019-c

✦ Synopsis

Temperature dependence of ~H spin-lattice, Tt (H), and spin-spin, T2(H ), relaxation times of isotactic polypropylene samples with different microtacticity was investigated. The samples were crystallized at high temperature (155°C) for a long time (200hr). The sample with high microtacticity (mmmm =0.98) shows longer TI(H ) and shorter T2(H ) than the sample with low microtacticity (mmmm = 0.92). In contrast, there are no substantial differences in ~3C magnetic relaxation times such as spin-lattice relaxation time, T t (C), and spin-lattice relaxation time in the rotating frame, Tip(C). There are also no large differences in ~H spin--lattice relaxation time in the rotating frame, Ttp(H), and a time constant characterizing proton spin diffusion, T~, between two samples.