In order to study the crystal structure of polypropylene obtained by cooling melt near melting point under shear flow

samples were prepared by using a dynamic packing injection molding (DPIM) device which was designed by ourselves.With the aid of scanning electron microscopy (SEM)

differential scanning calorimetry (DSC) and wide-angle x-ray diffraction (WAXD)

crystal stuctures and morphologies were studied from skin to shear regions in these samples obtained by cooling melt near melting point under shear flow （DL）.Compared with the samples molded with traditional injection molding （SL）and the samples molded with high melt temperature（DH）

SEM results indicated that crystal structures and morphologies in DL had been greatly affected.Oriented crystal stuctureswere formed from skin to shear regions in DL

and no shish-kebabs could be found in these samples.DSC results showed that the dimension of lamellae in DL is bigger than that in SL and DH .WAXD test exhibited

compared with SL and DH

the dimension of crystal plane （110，040 and 130） is not greatly changed in DL.