Synthesis and characteristics of poly(ethylene terephthalate) with EO‐PO‐EO triblock copolymers: A thermal and mechanical property study

Abstract

AbstractA series of multiblock copolymers poly(ethylene terephthalate)‐co‐poly(ethylene glycol)‐poly(propylene glycol)‐poly(ethylene glycol) (PET‐X%‐E‐P‐E) were synthesized from dimethyl terephthalate (DMT), ethylene glycol (EG) and poly(ethylene glycol)‐poly(propylene glycol)‐poly(ethylene glycol) (E‐P‐E) with a two‐step procedure via melt polymerization. The structure, composition, crystallization behavior, and thermal stability of the synthesized copolymers were determined by 1H‐NMR, FT‐IR, XRD, DSC, and TGA measurements. All samples exhibited good thermal stability at a Td‐5% above 300°C. DSC results revealed an increment trend of crystallization ability of copolymers in lower E‐P‐E content and then decreased when E‐P‐E concentration gradually raised to 40 wt%. Furthermore, the mechanical properties of copolymers were investigated systematically; the incorporation with E‐P‐E segments significantly enhanced the toughness and water absorption ability. Impact strength increased from 670.46 to 4448.75 J/m2, and water absorption values raised from 0.7% to 3.4% of the content of E‐P‐E increased. The stress–strain curve exhibited that tensile strength reduced from 40.38 to 17.88 MPa, the elongation at break increased from 4.6 to 27.9%. These new tough PET materials have an important application in toughness polyester fiber by the melt‐spinning techniques.