Synthesis And Evaluation Of Novel Nucleating Agents Of Polypropylene

Polypropylene (PP) has been used extensively as a raw material of composites because of its simple synthetic technology, low price and excellent comprehensive properties, however, the low impact strength and stiffness at high temperature and high shrinkage limite its application. Nucleating agents have an effect on the crystalline morphology of PP and improve the performance and processability of PP.Modifying with nucleating agent would widen the field of application of PP. Therefore, nucleating agents have been employed to modify PP as a significant means.In order to select effective nucleating agents of PP, the new layered materials, SiY1 and SiY2 were prepared with Si(OC₂H₅)₄ and CH₃(CH₂)₁₆COOH; and the new nucleating agents TiB1 and TiB2 were synthesized with Ti[OCH(CH₃)₂]₄ and C₆H₅COOH; and another new nucleating agents TiY2 were synthesized with Ti[OCH(CH₃)₂]₄ and CH₃(CH₂)₁₆COOH. The thermodynamic stability was investigated by TGA. The effects of following several kinds of nucleating agents on crystallization performance, heat resistance and mechanical properties of PP were characterized by X-ray diffraction (XRD), polarized optical microscopy (PLM), differential scanning calorimetry (DSC), Vicat softening point test and tensile strength, impact strength and flexural strength tests. And more synergistic effect of nucleating agents and zeolites was investigated.The results showed that, the layered materials of SiY1 and SiY2 induce PP to formβphase. The impact strength of PP/SiY1 and PP/SiY2 increase from 11.28kJ/m² of PP to 38.33 kJ/m² and 44.5kJ/m², respectively. The tensile strength and the flexural strength of PP decreased slightly. The crystallinity of PP/SiY2 increased obviously. The photo of PLM showed that the spherocrystal of PP became more homogeneous obviously.The pattern of XRD revealed that TiB1 and TiB2 are the nucleating agents of valid a crystal type. The crystallization temperature and the crystallinity PP/ TiB1 and PP/TiB2 increased obviously. TiB1 and TiB2 improved the Vicat softening point of PP too. The photoes of PLM showed that the mophology of spherocrystal of PP were changed obviously,and the spherocrystal was refined with addition of TiB1 and TiB2.The impact strength of PP/TiB1 and PP/TiB2 increased from 11.28kJ/m² to the 28.52 kJs/m² and 23.58 kJs/m², respectively. The tensile strength and the flexural strength of PP also increased significantly.It is advantageous to the mechanical properties of PP that the synergistic effect of zeolite 5A and layered material SiY1, SiY2.The composites TiY2-13X, TiY2-5A and TiY2-4A mixed by TiY2 and a series of zeolites 4A, 5A and 13X were also used to be nucleating agents. The impact strength of PP/TiY2, PP/TiY2-13X, PP/TiY2-5A and PP/TiY2-4A increased from 11.28kJ/m² to 36.69 kJ/m²,34.49 kJ/m²,38.33kJ/m² and44.0kJ/m², respectively. The tensile strength and the flexural strength of PP alsoincreased too. And the photoes of PLM indicated that the spherocrystal wasrefined.