An Unusual Crystallization Peak of Poly (vinyl chloride) TIEQI LI, 1,2 KUN QI 1 1 Department of Materials Science and Engineering, Guangdong University of Technology, Guangzhou, 510090 2 Materials Science Institute, Zhongshan University, Guangzhou 510275, People’s Republic of China Received 27 June 1996; accepted 6 September 1996 ABSTRACT: Owing to an efficient quenching process that ensure r-poly ( vinyl chloride ) to be amorphous enough, crystallization of rPVC at lower temperatures has been found in samples with various processing histories. Through a modified Avrami analysis, kinetics of the isothermal crystallization at these low temperatures was studied, prov- ing that the crystal growth in the studied temperature range was controlled by segment mobility, which should follow a WLF-type relationship. Such a mechanism is unusual compared to ordinary growth controlled by chain reptation. Also discussed were implica- tions of the results to further crystallization study of PVC and to that of polymers in general. The treatment distinguished itself in that it can give out both spacial growth exponent and dependency of the dimension on time.  1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1747 – 1754, 1997 Keywords: PVC; cold crystallization; kinetic analysis INTRODUCTION dom be found in commercial PVC. 4,12 Therefore, rather than being a proper description of micro- crystals as for many other polymers, 13 the lamil- The crystallinity in poly(vinyl chloride) (PVC) lae model was able to be formulated 7 only on a plays an important role in the gelation of PVC tutorial background. Lack of thermodynamic data rigid compounds. 1–3 Though crystallinity in com- has seriously hindered the understanding of crys- mercial suspension-polymerized PVC is generally tallization. in r-PVC. as low as about 10% by weight, 4,5 the endotherms To avoid difficulties in morphology observation on DSC curves have been experientially used to that originate from imperfection and poor crystal- characterize the level of its fusion or gelation. 1–3 lization ability of the PVC, kinetic studies are nec- Poor knowledge about the nature of melting and essary through sensitive methods, such as differ- recrystallization prohibits further development of ential scanning calorimetory. In this work, a novel the method. Although lattice parameters had crystallization peak was found in a temperature been obtained from PVC/DOP gel, 6 lamellar range of about 10°C higher than the glass temper- thickness calculated from WAXD data, 5,7 and iso- ature. Isothermal experiments were carried out thermal crystallization kinetics studied to find an to analyze its kinetics, following the original Avrami exponent near to unity, 8,9 the tacticity methodology of Avrami. 14–16 necessary to ensure the crystallization 10,11 can sel- Correspondence to: T. Li. EXPERIMENTAL Contract grant sponsor: Guangdong University of Tech- nology. A mass suspension-polymerized PVC ( TK800, Contract grant number: 932027.  1997 John Wiley & Sons, Inc. CCC 0021-8995/97 / 131747-08 Nippon Shinetsup, Japan ) was dry-blended with 1747 8e8f 3897 / 8E7C$$3897 01-27-97 15:33:48 polaas W: Poly Applied