The Synthesis And Application Of New-typed Polypropylene Nucleating Agent

Polypropylene(PP) has excellent integrated properties, such as nontoxic, relatively low density, able to endure erode, ease to process and excellent mechanical properties etc. However, there are some defects on PP itself, for instance, low impact strength, bad heat resistance and low transparaency etc, which have limited the range of application of the PP material to a great extent. In recent years, study and development on modified PP becomes the main direction of PP commerce. The performance of PP can be improved by modifying crystallization behavior of PP with adding nucleating agents. Modifying PP with nucleating agent is a practical and reliable method and also is a research hotspot of PP development recently.A series of new-typed nucleating agents were designed and synthesized in this study, these nucleating agents include:The nucleating agent SYLG prepared with calcium phthalate and a layered material .The layered material was synthesized by tetraethyl orthosilicate and stearic acid.The nucleating agents of SY1B,SY2B and SY3B were synthesized by tetraethyl orthosilicate , stearic acid and boric acid.The nucleating agents of AlY, AlB and AlD were synthesized by aluminate isopropyl ester and stearic acid, benzoic acid and p-tert-butylbenzoic acid.The effects of these nucleating agents on crystallization performance and mechanical properties were investigated with X-ray diffraction (XRD), differential sanning calorimeter (DSC), polarizing microscope(PLM) and tensile strength, impact strength and flexural strength tests.The results showed that, the nucleating agents of SYLG series induce polypropylene to crystallize inβphase, the content ofβ-phase in polypropylene was respectively 65.80% and 60.34% when the addition of SY1LG1-2 and SY2LG1-2 were 0.3wt %, and the crystallization temperature increased by 11.58℃and 9.13℃respectively, but crystallinity of polypropylene was decreased. SYLG made spherocrystal grain refining and blured the interface of spherocrystal. The impact strength of PP increased with the addition of SYLG series, especially when the content of SY2LG1-2 was 0.3wt%, the impact strength of the PP increased by three times, and the tensile strength and the flexural strength had little change.SY2B and SY3B induced PP to crystallize in a phase and made the Spherulite perfect. SY1B inducedβ-phase PP partly, and with the increase of addition of nucleating agent, the content ofβ- phase also increased. SY1B, SY2B and SY3B improved the impact strength of PP, but had little effect on the tensile strength of PP. When the addition of SY1B was 0.3wt% the flexural addition of nucleating agent, the content ofβ- phase also increased. SY1B, SY2B and SY3B improved the impact strength of PP, but had little effect on the tensile strength of PP. When the addition of SY1B was 0.3wt% the flexural strength decreased 6.25MPa, but with the same cotent of SY2B and SY3B the flexural strength of PP improved slightly.The nucleating agents of AlY, AlB and AlD induce PP to crystallize in a phase and they can increase the crystallization rate of polypropylene. When the contents were 0.3wt%, the crystallization temperature respectively increased 6.28℃, 5.90℃and 12.07℃. The crystallinity increased by 7.84% and 2.68% with the addition of AlB, AlD.The mechanical properties results show that, the nucleating agents of AlY, AlB and AlD increased the impact strength of PP, especially when the content of AlY was 0.3wt%, the impact strength increased by 20.70kJ/m~2 . The tensile strength and the flexural strength of PP increased firstly, and then decreased slightly with the addition of AlY and AlD. AlB increased the tensile strength and the flexural strength.