Nano calcium carbonate strengthened microcrystal polypropylene composite material synthesized by supercritical fluid rapid diffusion method

Abstract

The invention realizes the even distribution of nano calcium carbonate in PP (Polypropylene) by carrying out filling modification on the PP through applying a supercritical CO2 rapid diffusion technology, thereby greatly improving the stability and the mechanical performance of the modified material. The supercritical CO2 plays a role of plasticization on the PP by unique gas-liquid two-phase performance in the production process, the melting temperature of the PP is reduced, and meanwhile, CaCO3 is uniformly distributed in the PP by the high diffusion and permeability of supercritical CO2. The invention researches a high-performance nano CaCO3 filled microcrystal PP powder. The effect of a microcrystal attributes to the sharp diffusion process from a supercritical state to normal temperature and normal pressure of the whole system; a crystal nucleus of the PP is too late to grow due to the sharp performance of conversion; the optical performance and the transparency are greatly improved by great reduction of the sphaerocrystal size, and the microcrystal structure is beneficial to reducing the contraction of a final injection molding product; and the invention improves the size stability of products and is an ideal high-grade automobile special material.

Description

technical field [0001] The invention belongs to the field of polymer composite materials in material science, and relates to a nano-calcium carbonate reinforced microcrystalline polypropylene composite material and an advanced preparation method thereof. The invention improves the diffusion problem of the micro-nano filling particles in the polypropylene matrix, improves the crystal form of the polypropylene, and greatly reduces the size of the spherulites. The nano-composite material prepared by the method of rapid diffusion of supercritical carbon dioxide has the characteristics of good fluidity, high hardness, good dimensional stability, and scratch resistance. It is an ideal special material for high-end automobiles. Background technique [0002] Among the automotive modified plastics, the modified plastic based on polypropylene PP is currently the most widely used one, and the modification method is mainly filled with inorganic substances. With the development of new t...

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Problems solved by technology

However, due to the violent agglomeration tendency among nanoparticles, how to distribute nano-calcium carbonate uniformly in PP so as to achieve a better connection between the filler phase and the matrix has become a difficult point in the field of modified plastics today.

At present, the most commonly used method to solve this problem is to add an appropriate amount of coupling agent in the twin-screw extrusion process. This method is difficult to ensure the performance stability of the material between batches, and the use of some organic solvents is not conducive to The concept of environmentally friendly production

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