Polyethylene glycol terephthalate/polyethylene glycol(poly tetramethylene glycol)/Montmorillonite intercalated block copolymers, PET/PEG (PTMG)/MMT, were synthesized with different mass fractions and molecular weights of PEG. The dispersion of MMT in copolymer matrixes and the influence of PEG or PTMG on the crystallization behavior of PET/MMT were studied. It was revealed that MMT layers were dispersed at nano-scale in PET/PEG matrixes. PEG or PTMG segments improved the flexibility of PET molecular chain...