Preparation Of PP/LDH Nanocomposites With AA Modified LDH

Layered double hydroxides(LDH) is a kind of environmental friendly inorganic materials, it can be used as a filler added into the polyolefin which can not only save non-renewable resources but aslo make polyolefin obtain more excellent performance. Therefore, PP/LDH composites become a hot topic gradually. In this paper, sodium dodecylsulfonate anion firstly intercalated Mg Al-CO3 layered double hydroxides(LDH) by ion exchanged method to extend the interlayer spacing and make acrylic acid(AA) intercalate easier. Then, acrylic acid was brought in it. Combine polypropylene(PP) with sodium dodecylsulfonate/ acrylic acid modified LDH(AA-LDH) and peroxide initiator, by means of melting intercalation and grafting reaction to prepare PP/LDH composites in the twin-screw extruder. The best technical parameters was obtained. This article will provide a theoretical basis for preparing PP/LDH composites with excellent performance. The main arguments are as follows:1.Factors such as p H value, reaction temperature, reaction time, molar ratio of AA and LDH were studied how to effect the ion exchanged reaction. The results show that, by controlling the reaction conditions, AA-LDH can be obtained through hydrotalcite precursor. Sodium dodecylsulfonate anion and acrylic acid were confirmed substitute the original CO32- into LDH layer by X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR). By comparing the variation of interlayer spacing, intercalated rate and residual volume of CO32- in the layer, we obtained the best reaction conditions: p H=4?T=70??t=3h?the molar ratio of AA/LDH=1?2.The influence of chemical parameter and machining parameter on the AA-LDH and PP grafting reaction was investigated by control variable method. The best technical parameters was obtained by comparing grafting ratio, mechanical property of PP/LDH composites and gel ratio: when PP=100g, the dosage of AA-LDH was 5.0g, the dosage of DCP was 0.2g, T=190?, rotate speed was 5Hz. The highest grafting ratio was about 1.45 wt%.3.By studying the isothermal crystallization behavior of composites, the crystallization rate of PP/AA-LDH composites show a trend of rise first and then decreased. The higher of grafting rate, the bigger of the crystallization rate. When the content of additive in the same conditions, the addition of AA-LDH and unmodified LDH particles act as nucleating agents to facilitate the crystallization process, just AA-LDH performed better. By studying the nonisothermal crystallization behavior of composites, grafting effected on the crystallization of PP in two aspects:(1)it performed nucleation to facilitate the crystallization process of PP;(2)graft polymer can destroy the crystalline regularity to influence the crystallization process and regularity.