Reference

Polylactones

Polylactones. 1. Copolymerizations of glycolide and e-caprolactone. Kricheldorf, Hans R.; Mang, Thomas; Jonte, J. Michael (Inst. Angew. Chem., Univ. Hamburg, Hamburg D-2000/13, Fed. Rep. Ger.). Macromolecules, 17(10), 2173-81 (English) 1984. CODEN: MAMOBX. ISSN: 0024-9297. DOCUMENT TYPE: Journal CA Section: 35 (Chemistry of Synthetic High Polymers) Section cross-reference(s): 36 Copolymn. of glycolide [502-97-6] with e-caprolactone [502-44-3] was conducted in bulk at 100° and in PhNO2 or dioxane at 70, 100, or 150°. The resulting copolyesters (I) [41706-81-4] were characterized with respect to their molar compn. by means of 1H NMR spectra and with respect to their sequences by means of 13C NMR spectra. The results allow a classification of both I and initiators. Cationic initiators such as FeCl3, BF3, and FSO3H favor the incorporation of e-caprolactone, catalyze intermol. transesterification, and cause rapid degrdn. of I above 100°. Complexing catalysts such as ZnCl2, Al(OPr-iso)3 [555-31-7] and Bu2Sn(OMe)2 [1067-55-6] favor the incorporation of glycolide and chem. heterogeneity of 1st order. Furthermore, intramol. transesterification was detected in the case of Al(OPr-iso)3 and Bu2Sn(OMe)2. Anionic catalysts such as Et4N+ PhCO2- [16909-22-1] and Ph3P+CH2Ph Cl- [1100-88-5] only initiate the homopolymn. of glycolide. The polymn. mechanisms are discussed. The differential scanning calorimetry shows a close relationship between crystallinity and nature of sequences.

Scorch-resistant fluoro rubber compositions

Scorch-resistant fluoro rubber compositions. (du Pont de Nemours, E. I., and Co., USA). Japan. Kokai JP 52040558 29 Mar 1977 Showa, 10 pp. (Japanese). (Japan). CODEN: JKXXAF. CLASS: IC: C08L027-12. PRIORITY: US 75-616825 25 Sep 1975. DOCUMENT TYPE: Patent CA Section: 38 (Elastomers, Including Natural Rubber) Compns. of 40-95 parts fluoro rubber derived from CH2:CF2 and other fluoro compds., 5-60 parts rubbery copolymers derived from 90-8 mol% Et or Bu acrylate and 2-10 mol% vinyl compds. having active Cl or epoxy groups, 0.1-5% (based on total compn.) bis(4-hydroxyphenyl) sulfone (I) [80-09-1], and 0.1-3.0% phosphonium compds. or ammonium compds. have good scorch resistance. Thus, a compn. of hexafluoropropylene-vinylidene fluoride copolymer [9011-17-0] 75, 97.2:2.8 (molar) Et acrylate-vinyl chloroacetate copolymer [26426-73-3] 25, I 2, carbon black 20, MgO 3, Ca(OH)2 3, and benzyltriphenylphosphonium chloride [1100-88-5] 0.9 part had Mooney scorch time (5 points up) 34 min at 121° and its vulcanizates (10 min at 180° and 18 kN and 24 h in air at 177°) had Shore hardness A68 and A75 before and after 70 h at 177°, resp., 100% modulus 4.2 and 5.44 MPa, resp., tensile strength 9.78 and 9.78 MPa, resp., and elongation 220 and 180%, resp., compared with 10, A71, A71, 4.2, 5.44, 8.99, 9.47, 200, and 180, resp., for a similar compn. contg. 4,4'-hexafluoroisopropylidenebisphenol in place of I.