Research On Preparation And Properties Of Thermoplastic Polyurethane Toughened Poly Lactic Acid Meltblown Nonwovens

With the fast development of society,the application of meltblwn nonwovens(MBN)has become more and more widespread nowadays.MBN materials are gradually replacing the traditional materials in some fields such as medical(mask,bandage),filtration membrane,health supplies as a result of excellent feature and performance.In recent years,for producing the superfine meltblown fabrics there has been considerable interest has grown up in the MB process from both commercial and scientific viewpoints.Polylactic acid(PLA)is biodegradable,biocompatible and renewable thermoplastic polyester which is mainly derived from corn starch has drawn a plentiful interest in this sector for manufacturing biodegradable nonwoven products that shows strong market competitiveness due to its ultrafine fiber structure and environmental friendliness.However,PLA has limited its application due to its lack of mechanical toughness.In this thesis paper,high fluidity thermoplastic polyurethane(TPU)is used as the toughening material for PLA,and the PLA/TPU composite masterbatches for MBN prepared by the melt blending method,and its phase structure,thermal crystallization performance,thermal stability and the crystal structure changes were studied,and PLA/TPU MBN were further prepared.The results show that PLA and TPU are incompatible systems,and TPU has almost no effect on the crystallization process and crystal structure of PLA,but it reduces the thermal stability of PLA.The blending mass ratio of TPU is less than20%,and the MBN process ability of PLA/TPU is better.PLA/TPU MBN material exhibits better strength and tensile ductility than a single PLA MB material.With the improvement of research in biomedical applications such as tissues Engineering scaffolds and fracture fixation devices even PLA can replace the stainless steel and metallic medical devices.However,PLA shows some inherent drawbacks such as low thermal stability and crystallization speed,ductility,brittleness etc.For fulfill the requirement of any special use of PLA MBNs the use of some compatibilizers and treatment is highly required.Therefore,the preparation of flexible PLA melt blown nonwoven fabrics has extensive research significance and application value.In this thesis,different ratios of PLA and TPU blending materials had been prepared and the thermal properties,crystallization,morphology and melt flowing rate were studied.The properties of the material such as thermal,mechanical were characterized by using scanning electron microscopy(SEM),differential scanning calorimeter(DSC),wide-angle X-ray diffraction(WAXD).In the second part of the thesis PLA/TPU blending materials thermal properties,and rheological properties were investigated with the help of melt flow meter and capillary rheometer.As well as the PLA and TPU blended fibers were produced and investigated the apparent morphology,melt spinning and tensile mechanical properties.In the final part of thesis,the morphological structure and mechanical properties of different proportion of PLA and TPU MBN fabrics were tested and analyzed.It was found that Adding compatibilizer in the PLA/TPU blend improved performance of the composite master batches and as well as it improved the mechanical properties of the MBN fabrics.