Orientation Microstructure and Properties of Poly(propylene carbonate)/Poly(butylene succinate) Blend Films G. J. Chen, Y. Y. Wang, S. J. Wang, M. Xiao, Y. Z. Meng The Key Laboratory of Low-carbon Chemistry & Energy Conservation of Guangdong Province, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, People’s Republic of China Correspondence to: Y. Z. Meng (E-mail: mengyzh@mail.sysu.edu.cn) or M. Xiao (E-mail: stsxm@mail.sysu.edu.cn) ABSTRACT: The blends of high molecular weight poly(propylene carbonate) (PPC) and poly(butylene succinate) (PBS) were melt blended using triphenylmethane triisocyanate (TTI) as a reactive coupling agent. TTI also serves as a compatibilizer for the blends of PPC and PBS. The blend containing 0.36 wt % TTI showed that the optimal mechanical properties were, therefore, calendared into films with different degrees of orientation. The calendering condition, degree of orientation, morphologies, mechanical properties, crystallization, and thermal behaviors of the films were investigated using wide-angle X-ray diffraction, scanning electron microscopy, tensile testing, and differential scanning calorimetry (DSC) techniques. The result showed that the as-made films exhibited obvious orientation in machine direction (MD). Both tensile strength in MD and the tear strength in transverse direction (TD) increased with increasing the degree of orientation. The orientation of the film also increased the crystallinity and improved the thermal prop- erties of the PPC/PBS blend films. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 390–399, 2013 KEYWORDS: poly(propylene carbonate); poly(butylene succinate); triphenylmethane triisocyanate; calendared film Received 22 February 2012; accepted 31 May 2012; published online 3 July 2012 DOI: 10.1002/app.38150 INTRODUCTION The development of plastics industry had serious consequences for the environment, called ‘‘White Pollution,’’ 1 because of their not biodegradability. In recent years, much attention has been paid to aliphatic polyesters; they show good biodegradability and excellent comprehensive performance. For instance, poly (lactic acid) (PLA), poly(3-hydroxybutyrate-co-3-hydroxyvaler- ate), and poly(butylene succinate) (PBS) are the outstanding representatives of them. 2–8 Moreover, the mass emission of CO 2 produced by industries is believed to cause the global warming that may contribute to the climate change. 9–11 On the other hand, the utilization of CO 2 as resource has attracted more and more researcher of late years; the copolymerization of CO 2 with epoxide to form biodegradable aliphatic polycarbonate is one of the promising ways. 12–16 The fixation of CO 2 in the synthesis of biodegradable polycarbonate not only eases dependence on pe- troleum but also reduces the massive emission of CO 2 , which can mitigate the greenhouse effect. In previous works, high molecular weight poly(propylene car- bonate) (PPC; M n > 250,000) has been successfully synthesized from CO 2 and PO using supported catalyst under optimized reaction conditions, and alternating PPC in very high yields (126 g of polymer per gram catalyst) has also been synthesized successfully in our laboratory. 17–19 PPC with alternating molec- ular structure exhibits fairish mechanical properties and consid- erable degradability in surroundings of both soil and buffer sol- utions. However, poor thermal properties limit its practical application areas. PPC possesses many particular characteristics. Its amorphous na- ture can endow many unique properties, such as highly oxygen barrier property. On the other hand, to produce PPC-based films, it is very important to improve its melt and static strength. 20–24 PBS is aliphatic polyester with semicrystalline structure and bio- degradable nature. Because of its high crystallinity and crystalline structure, it exhibits excellent mechanical properties and thermal stability. 7,25 In our previous work, we reported the miscibility and properties of PPC/PBS blends. 26 The compatibility between PPC and PBS can be effectively improved by simple melt compound- ing in the presence of compound containing reactive groups. Both PPC and PBS have terminated hydroxyl groups, which can then react with isocyanates to enhance the comprehensive proper- ties of PPC/PBS blends (Figure 1). Numerous works using isocya- nates as reactive agent have been reported. 27,28 For example, Zeng et al. 29 used toluene diisocyanate as chain extender to synthesize multiblock poly(ester urethane), consisting of poly(L-lactic acid) and PBS blocks; Harada 30 prepared PLA/PBS blends using lysine V C 2012 Wiley Periodicals, Inc. 390 J. APPL. POLYM. SCI. 2013, DOI: 10.1002/APP.38150 WILEYONLINELIBRARY.COM/APP