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

Abstract A 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 1 H‐NMR, FT‐IR, XRD, DSC, and TGA measurements. All samples exhibited good thermal stability at a T d‐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/m 2 , 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.