Critical Of Co <sub> 2 </ Sub> Application In The Preparation Of Microporous Polymer Film Of Polypropylene Modified And Rules

Supercritical carbon dioxide (SC CO₂) has many unique properties, such as low viscosity, high diffusivity, near zero surface tension, nonflammable, nontoxic, mild critical conditions and so on. In addition, its solvent strength could be continuously tunable from gas-like to liquid-like by changing temperature or pressure. So SC CO₂ technology has been widely used in preparation and chemical modification of polymer.Polypropylene (PP) is one of the most important general purpose polymers widely used in various fields, but its non-polarity restricts its application. So graft copolymerization by hydrogen abstraction from teriary carbon offers an effective approach to introduce some desirable properties and expands its application. In order to avoid the disadvantages of traditionary grafting methods, SC CO₂ technology has been employed in this field. Monomer and initiator was impregnated into PP matrix using SC CO₂ as solvent and swelling agent. And then, grafting reaction was took place at appropriate temperature to obtain grafted sample. In this work, three system of grafting of maleic anhydride and styrene to PP, grafting of acrylamide to PP and grafting of acryl acid to PP have been studied. The effects of impregnated temperature, impregnated pressure, impregnated time, monomer concentration, initiator concentration and grafting temperature on grafting rate, and the complex relation of teriary system of PP matrix/SC CO₂/monomer and initiator have been studied. From these experiments we put forward the concept of grafting efficiency and obtained the tendency of it with change of experimental conditions. The original and grafted samples were also investigated by infra-red spectrum (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and micropolariscope (POM).Recently, more and more people focus on the ordered micro-pattern polymer films due to potential application in lots of fields. Now the methods of preparation of these materials are mainly templating and self-assemble of copolymer. In this work, we designed a kind of main chain fluorinated liquid crystalline polymer to produce...