Fracture Behavior of Poly(trimethylene terephthalate) Toughened by Maleic Anhydride Grafted Styrene-Ethylene-Butadiene-Styrene Block Copolymer

Abstract

Maleic anhydride grafted styrene-ethylene/butadiene-styrene block copolymer (SEBS-g-MA) was introduced into poly(trimethylene terephthalate) (PTT) to prepare the PTT/SEBS-g-MA blends. The results showed that SEBS-g-MA exhibited dispersed particles and the particle sizes changed with the variation of its content. Furthermore, the crystallization behavior of PTT matrix was restricted by adding SEBS-g-MA. Mechanical properties measurements proved that PTT could be toughened by SEBS-g-MA and the toughening effect was greatly dependent upon the SEBS-g-MA content and the measurement conditions. The toughening mechanism was mainly attributed to the largely enhanced resistance of the crack propagation during the fracture process. INTRODUCTIONPoly(trimethylene terephthalate) (PTT) is a linear aromatic polyester with better elasticity, dimension stability and dyeability compared with other polyesters such as poly (ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT), and it has wide application in the field of textile [1][2][3][4][5][6][7] . Furthermore, PTT is also a semicrystalline polymer, and its crystallization ability is relatively better than PET [8] , which endows it with great potential application as an engineering plastic. Although PTT exhibits excellent tensile strength and modulus, the impact strength is relatively poor, and is very sensitive to the sharp notch. Therefore, toughening PTT attracts much attention in the past years.It is well known that rubber or elastomer is the most efficient material that improves the fracture toughness of brittle matrix. So far, nearly all the toughening methods of PTT are related to the use of elastomers in PTT. However, as reported in the literature, the common elastomers that exhibit apparent toughening effects for PTT are relatively few possibly due to the poor interfacial interaction between elastomer and PTT matrix [9] . This is apparently different from the toughening of PET in which different kinds of elastomers, whether they are apolar or polar, are widely used [10][11][12] . So far, most of the researches have been focused on the direct use of polar elastomers or functionalized elastomers. These elastomers include maleic anhydride grafted ethylene-propylene-diene copolymer (EPDM-g-MA) [13][14][15] , maleic anhydride grafted acrylonitrile-butadiene-styrene (ABS-g-MA) [16,17] , maleic anhydride grafted styreneethylene=butadiene-styrene (SEBS-g-MA) [18] , maleic anhydride grafted poly(ethylene-octene) (POE-g-MA) [19,20] .In addition, the other toughening methods of PTT are related to the use of the vulcanized thermoplastics and coreshell particles. For example, Savadekar and Mhaske [21] introduced vulcanized thermoplastics based on polypropylene (PP) and EPDM, i.e., PP-g-EPDM, into PTT and found that the impact strength was significantly increased with the increase of PP-g-EPDM content. Wang et al. [22] introduced polybutadiene grafted polymethyl methacrylate (PB-g-PMMA) into PTT. The PB-g-PMMA exhibited a core-shell structure. When diglycidyl ether of ...