Effect of rare earth β-nucleating agent on crystallization and foaming properties of polypropylene
A variety of nucleating agents were introduced into long-chain branched polypropylene(LCBPP)to investigate the β-crystal nucleating effect of a nucleating agent WBG-Ⅱ in the LCBPP/isotactic polypropylene(iPP)blends as well as to evaluate their impact on the mechanical properties and foam structure of formed PP materials.The as-prepared sam-ples were characterized by X-ray diffraction,differential scanning calorimetry,and rotational rheometer to identify the highly effective β-crystal inducer,WBG-Ⅱ.The results indicated that the addition of 5 phr WBG-Ⅱ resulted in an in-crease in the impact strength of LCBPP by 128％,whereas its tensile strength decreased by above 20％.Additionally,the nucleating agent had no significant adverse effect on the melt strength of LCBPP.Polarized optical microscopy(POM)observations further revealed that WBG-Ⅱ effectively induced the β-crystal orientation in iPP.Incorporating iPP into the LCBPP matrix significantly increased the β-crystal content in the blend.Compared to pure LCBPP,there was an increase in the crystallinity degree by 190％for the LCBPP/iPP sample at a mas ratio of 1/1.Furthermore,the addition of iPP enhanced the storage modulus and complex viscosity of the PP blend under high-frequency conditions.
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