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| Titel: |
Preparation and Molecular Structure of Poly(Vinyl Alcohol) by Low Temperature Bulk Polymerization of Vinyl Acetate and Saponification |
| Auteur: |
Lyoo, Won Seok Lee, Chul Joo Park, Ki Hong Kim, Nakjoong Kim, Byoung Chul |
| Verschenen in: |
International journal of polymeric materials |
| Paginering: | Jaargang 46 (2000) nr. 1-2 pagina's 181-194 |
| Jaar: |
2000-06-01 |
| Inhoud: |
Vinyl acetate (VAc) was bulk-polymerized at 30, 40 and 50°C using a low temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN), and effects of polymerization temperature and initiator concentration were investigated in terms of polymerization behavior and molecular structures of poly(vinyl acetate) (PVAc) and corresponding poly(vinyl alcohol) (PVA) obtained by saponifying it with sodium hydroxide. Low polymerization temperature and low conversion by adopting ADMVN proved to be successful in obtaining PVA of high molecular weight. PVAc having number-average degree of polymerization (Pn) of 6,800-10,100 was obtained, whose degree of branching for acetyl group of 0.6-0.7 at 30°C, 0.8-1.1 at 40°C, and 1.0-1.9 at 50°C at conversion of below 40%. Saponifying so prepared PVAc yielded PVA having Pn of 3,100-6,200, and syndiotactic diad (S-diad) content of 51-53%. The whiteness, S-diad content, and crystal melting temperature were higher with PVA prepared from PVAc polymerized at lower temperatures. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 26 van 35 gevonden artikelen
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