97
Table 1. St-VAc blockcopolymers Table 2. Stability of dispersion of blockcopolymers in unsaturated polyester
(a) (b) (c) Fig. 1. Phase reversions of poly (St-b-VAc) in unsaturated polyester. Fig. 2. Shrink-resistance effect of poly (St-b-VAc) on unsaturated polyester: œ, SV 10;, SV 50;, Pst, PVAc; ~, control. Fig. 3. Shrink-resistance effect of poly (St, MAb-VAc) on unsaturated polyester: œ, SV 10A;, SV 50A;, VAc-MA copolymer.
a b
VI Fig. 4. Scanning electron micrographs of fracture surface of cured unsaturated polyester compounded with Poly(St-b-VAc) (9/1wt) a, fracture surface; b, after etching with benzene; I-IV, shown in Table 4. Table 3. Surface condition of unsaturated polyesters Table 4. Appearance of unsaturated polyester at each curing stage
a b
VI a Fig. 5. Scanning electron micrographs of fracture surface of cured unsat polyester compounded with PSt. a, fracture surface; b, after etching with benzene; I-VI, shown in Table 4. b
Table 5. Solubility parameters of polymers a Fig. 6. Scanning electron micrographs of fracture surface of cured unsat. polyester compounded with PVAc. a, fracture surface; I-III: shown in Table 4.
4) K.E. Atkins and J.V. Koleske, 31th Annual Tech. Conference, 1976, Reinforced Plastics Composite Institute, SPI. 5) B. Peltzer, G. Kampf, Colloid Polym. Sci., 255 (12), 1145 (1977). 6) T. Okada, Preprint, 3rd International Con- gress on Polymers in Concrete yama), Vol. I, p.407. (1981, Kori- Preparation of New Low Profile Additives for Unsaturated Polyester and Study on Their Behavior by Scanning Electron Microscopy* Kyosuke FUKUSHI*1, Yasuo MORIYA*1, and Takashi YAMAMOTO*1 Preparation of Block and Graft Copolymers and Their Applications. IV. Chemicals and Explosives Laboratory, Nippon Oil and Fats Co., Ltd. (Taketoyo-cho, Chita-gun, Aichi, 470-23 Japan) Block copolymers of styrene (St) and vinyl acetate (VAc) were prepared with a polymeric peroxide having several peroxy bonds in a molecule. They are excellent low profile additives for unsaturated polyesters. The curing of unsat. polyesters was observed by scanning electron microscopy, and the behavior of low profile additives was studied on the basis of solubility parameters. Poly (St-b-VAc) dispersed in a styrene solution, where PSt segments were outside and PVAc segments were inside of the micelles. When a styrene solution was mixed with unsat. polyester, phase inversion took place, turning PVAc segments to outside. At the final stage of curing, phase inversion again took place and poly (St-b-VAc) micelles with outside PSt segments separated as spheres. Voids formed in this process seemed to serve for prevention of shrinkage. A similar phenomenon was observed in the cases of low profile additives such as PSt and PVAc. KEY WORDS Block Copolymer/Polymeric Peroxide/Low Profile Additive/Unsaturated Polyester/ Polystyrene/Polyvinyl Acetate/Scanning Electron Microscopy/Solubility Parameter/ (Received May 14, 1986: Accepted July 7, 1986) [Kobunshi Ronbunshu, 44 (2), 97-106 (1987)]