Dynamic mechanical and solid-state NMR determination of molecular-scale heterogeneity in a raw elastomer, a microcrystalline polymer, and their blend

✍ Scribed by Seung-Yeop Kwak; Sang Yong Kim; Nobuyuki Nakajima

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 234 KB
• Volume: 35
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199703)35:4<709::aid-polb17>3.0.co;2-k

✦ Synopsis

Dynamic mechanical and solid-state 13 C nuclear magnetic resonance (NMR) analyses have been used to assess a molecular-scale heterogeneity in a raw elastomer (butadiene-acrylonitrile copolymer elastomer, NBR), a microcrystalline polymer (poly(vinyl chloride), PVC), and their 50/50 blend. The presence of the microcrystalline heterogeneity in PVC and in the blend was characterized by the temperature dependence of the frequency-swept dynamic mechanical behavior. The NMR T 1r relaxation experiments with cross-polarization (CP) and magic-angle spinning (MAS) revealed that (1) NBR contained a substantial fraction (ca. 27%) of a molecular-scale heterogeneity identified as butadiene blocks, (2) the fraction of microcrystallites in PVC was ca. 14%, (3) pure phases of both component polymers were present in the blend, dispersed in the mixed matrix, (4) the upper limit of the heterogeneous domains was estimated to be ca. 2.4 nm, and (5) fractions of heterogeneity tend to increase upon blending, indicating that the solubility of the butadiene block and syndiotactic PVC block decreases in the blend.