Poly(1-butene) was modified with rare earth -nucleating agents which were introduced in situ during bulk polymerization of 1-butene.The influence of nucleating agent amount on the molecular weight

melting temperature (Tm)

degree of crystallinity (c)

and crystallization behavior of resulting poly(1-butene) was investigated in detail by gel permeation chromatography (GPC)

differential scanning calorimeter (DSC)

polarizing microscopy (POM)

and wide angle X-ray diffraction (WAXD).The results show that with the increase of nucleating agent content the isotacticity of poly(1-butene) was slightly increased

the number-average molecular weight (Mn) was obviously improved and the molecular weight distribution was narrowed while the activity of Ziegler-Natta catalyst was somewhat decreased.The addition of rare earth -nucleating agents changed the crystallization behavior of polymers

the spherulite size of nucleated poly(1-butene) dramatically decreased compared with that of pure poly(1-butene) and tends to homogenization with the increasing of nucleating agents content

the c of poly(1-butene) is improved

especially when the addition of -nucleating agents is 300 mg

but dropped dramatically after this point.In addition

the rare earth -nucleating agents not only play an positive role in improving Tm by changing the proportion of forms Ⅰ' and Ⅲ

but also speed up the transformation of crystalline form from Ⅱ to Ⅰ

shorten the crystal transformation period.