Effect Of Amide Compounds On β-Nucleation Of Polypropylene Copolymer

The p-nucleation and mechanical properties of Polyproplylene block copolymer (PP-B) and Polyproplylene random copolymer(PP-R) with N,N’-dicyclohexylterephthalamide(DCHT) and N,N’-diphenyl terephthalamide(DPHT) which were synthesized by one-step method of acylation reaction in the lab were studied in this paper, and compared that with commercial amide nucleating agent TMB-5.Characterization of DSC, WAXD and polarizing microscope show that more than half of a crystal is induced into (3crystal, and original bulky spherulite changes to a large number of fine spherulites disorderly in PP-B when a small amount of DCHT, DPHT or TMB-5powder was added into PP-B respectively. All these prove that three kinds of amide compounds have good β nucleating effect for PP-B. Nucleating effect order is:TMB-5≥DCHT> DPHT.Notched impact strength is over100%at normal temperature, over60%at0℃, over50%at-15℃; tensile breaking strength is over60%and elongation at break is over55%of modified PP-B when0.10%of TMB-5or0.05%of DCHT was added into PP-B respectively. While, the improvement of mechanical properties of PP-B with DPHT is worse than DCHT and TMB-5.Effect of different extrusion processing conditions on DCHT β-nucleating PP-R was studied. Experiment results show that DCHT enhances β-nucleation of PP-R obviously when barrel temperature and screw speed of the single screw extruder increases, and the best optimal extrusion condition is barrel temperature of250℃and screw speed of120rpm for single-screw-extruder. The β crystal relative content is higher at high screw speed of twin-screw-extruder. The highest β crystal relative content is45%-50%.β nucleating effect of various kinds of amide compounds for PP-R was studied. Results show that both DCHT and TMB-5have good β nucleating effect for PP-R, which can induce partial a crystal in PP-R converts into β crystal, and make spherulite size decrease and original bulky spherulite change to random flower-like crystal morphology. The β crystal relative content is more than25%. While the effect of DPHT on β-nucleation of PP-R is worse than DCHT and TMB-5.In the processing of β nucleating modification for Polyproplylene random copolymer (PP-R), the results show that notched impact strength are increased over25%at room temperature and low temperature of0℃,-10℃, the elongation at break is over50%, the tensile yield strength and tensile breaking strength unchanged basically when the optimal dosage0.05%of TMB-5or0.15%of DCHT was added into PP-R respectively.