Modification Of Low Molecular Weight Polylactic Acid By Reactive Montmorillonite

Polylactic acid,which is derived from nature and returned to nature,is a clean and renewable biodegradable material that can meet the needs of human beings for environmentally friendly and sustainable economy.However,polylactic acid has poor thermal stability and poor toughness,which limit its development in the market.Modified by reactive montmorillonite,and due to the strong interaction between reactive montmorillonite and polylactic acid,the compatibility of montmorillonite with polylactic acid and its dispersibility in polylactic acid matrix are improved,and this will improve the thermal stability of polylactic acid and not sacrifice other properties at the same time.And it has great significance for the application of polylactic acid in the fields of disposable products and packaging.In this paper,the principle of cation exchange is adopted.sodium montmorillonite(Na-MMT)are modified by cetyltrimethylammonium bromide(CTAB)and 3-chloro-2hydroxypropyltrimethylammonium bromide(CTA),respectively,ordinary organic montmorillonite CTAB-MMT and reactive montmorillonite CTA-MMT were prepared,as well as the industrial grade reactive montmorillonite DK-2,Fourier infrared spectroscopy analysis,thermogravimetric analysis,and X-ray diffraction analysis were performed.Thermogravimetric analysis showed that the organic adsorption capacity of self-made CTA-MMT and CTAB-MMT was higher than that of industrial grade montmorillonite DK-2.The X-ray diffraction analysis showed that the interlayer spacing of CTAB-MMT was larger than that of DK-2,and the interlayer spacing of DK-2 is larger than that of CTA-MMT,but it is also proved once again that the content of organic components in self-made CTA-MMT and CTAB-MMT is higher than that of industrial montmorillonite DK-2.In order to improve the molecular weight of polylactic acid polymerized by one-step polymerization,and in order to prepare polylactic acid/montmorillonite composite material with high additive performance,this paper discusses the process conditions for one-step polymerization of polylactic acid to find out the best process conditions.Under this process condition,the effects of different montmorillonites and montmorillonite content on the thermal stability and mechanical properties of polylactic acid were also investigated.Fourier transform infrared spectroscopy analysis,thermogravimetry analysis,differential scanning calorimetry analysis,dynamic thermo-mechanical analysis,melt index analysis,plate rotation rheological analysis,and mechanical properties analysis found that the modification effect of polylactic acid that modified by ordinary organic montmorillonite is far less than that of reactive montmorillonite,and the self-made reactive montmorillonite CTA-MMT has slightly better modification effect on polylactic acid than industrial grade reactive montmorillonite DK-2;moreover,when the content of CTA-MMT at 4%,the thermal stability and mechanical properties exhibited by PLA are the most prominent.