The Molecular Weight And Distribution Of State Structure And Properties Of Polypropylene Gathered

In this paper, The molecular weight and its distribution were investigated by using the methods of differential scanning calorimetry (DSC), polarizering microscope and wide-angle X ray diffraction (WAXD) etc. The best formulation of transparent polypropylene (PP) was also investigated by using the method of orthogonal experiment.For PP/DA system, the results indicated that: The value of Mn, Mw and MWD of PP became small with the increase of the DA's content. The crystal speed rate was increased and the spherulitic size was reduced because of the molecular weight reduction and its distribution narrowing down. The disappearance of 6 crystal made the combination property of PP decrease and didn't have obvious improvement on transparency.For nucleating PP/DA system, the results indicated that: It had on effects on PP's molecular weight and its distribution with the adding of nucleating agent. By adding only one nucleating agent TM-3, the crystal temperature had obvious improvement; the crystallization rate had been accelerated; the Avrami exponential "n" had obvious reduction; the crystallization rate constant "Zc" had obvious increase. The formation ofβcrystal had been inhibited and its mechanical property, resistance to effect of heat and transparency are higher than pure PP's. With continued adding DA, PP's molecular weight decreased and its distribution became narrow which led to the further increase of PP's crystallization temperature and crystallization rate constant "Zc"; theβcrystal disappeared; but the value of "n" didn't have change. Some mechanical property parameters of the nucleating PP had a little decrease, but the main mechanical property index were also higher than PP's.For PP/PP140 system, the results indicated that: PP's melt flow rate had gradual enhancement with the increase of the PP140's content and it reflected the decrease of the molecular weight. The decrease of PP's molecular made the crystallization rate accelerate ; crystal size become small; the 6 crystal disappear; the way of nucleating had no change.With the increase of the PP140's content which also meant the decrease of the molecular weight, the tensile-strength had gradual increase; the changes of the flexural strength and the flexural modulus were slight; the impact strength and the extension at break rate were decreased.For nucleating PP/PP140/TM-3 system, the results indicated that: It made the synthesis performance of PP with addig nucleating agent lower than PP without adding nucleating agent. With crystallization rate accelerating, the crystal size became further small.The research on batch formula designing of transparent pp indicated that: When adding the content of nucleating agent A, nucleating agent B, nucleating agent C, PE were 0.3%, 0.4%, 0.15%, 5% respectively, the value of haze of transparent pp that we mad is the lowest, only 32.5%.