Dissertation > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Polymer physics and physical chemistry of polymers > The chemical nature of polymers

Study on Blending Modification of Poly (Lactic Acid)

Author WangNing
Tutor YuJiuGao
School Tianjin University
Course Polymer Chemistry and Physics
Keywords Polylactic acid Thermoplastic starch Plasticizer Carbon black Blends
CLC O631.3
Type PhD thesis
Year 2007
Downloads 1218
Quotes 6
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Melt blending and compounding technology, the PLA thermoplastic starch (TPS), acetyl tributyl citrate (ATBC) poly adipic -1, 3 - butanediol ester (PBA) and carbon black (CB) the blends plasticized and inorganic nano-filler composite modified to improve the performance and practicality of the PLA. PLA with the thermoplastic starch (TPS) is blended, not only reduces the PLA material costs, but also improve their application performance. Experimental results show that the water content is essential for plasticization of starch, dried starch is difficult to completely plasticized; also found that the presence of water so that the PLA hydrolysis occurs during melt processing, resulting in the PLA molecular weight reduction, performance deterioration. PLA Blends dispersibility in order to improve the anhydrous starch plasticizing effect, and improve the dry thermoplastic starch (DTPS), first using citric acid (CA) for promoting plasticizing agent over anhydrous starch and PLA / the DTPS blending system phase dispersant. The study found that the CA can significantly improve its plasticizing effect, and the melt fluidity, thereby effectively improving from PLA / DTPS Blends dispersibility of 2% by mass based on the dry starch. Dicumyl peroxide (DCP) lead to maleic anhydride (MAH) grafted PLA extrusion process using the \Experiments show that the PLA / DTPS blends in MAH and CA combined effect of dispersion and compatibility between the two phases significantly improve the performance of the PLA / DTPS blends has been significantly improved, the tensile strength of up to 40MPa, better than the strength of the PLA itself. According to the experimental results, summed CA and MAH on PLA / DTPS blends a the dispersion - graft collaborative compatibilization. Citric acid ester plasticizer, although able to effectively plasticized PLA, but due to severe precipitation affect the application of the citric acid ester. This article was first used the PBA as PLA plasticizer, Comparative study found that when the plasticized mass is greater than 20 wt%, PBA representing ATBC having a higher plasticizing efficiency. The elongation at break of the PBA plasticized PLA system can reach 600% or more, and be able to maintain the tensile strength of 23.7MPa. The PBA Add plasticized PLA film can effectively reduce the water vapor permeability, improved the PLA melt fluidity and processability. CB is not only possible to improve the tensile strength of the PLA material, a conductive polymer can also be biodegradable, and controllable conductivity of the material by controlling the concentration of the the composite system plasticizer CB. The CB via the ATBC or the PBA infiltration process, can significantly improve the compatibility between the CB PLA matrix to obtain a high dispersion PLA / CB composite system. After adding a plasticizer, the conductivity of the composite system of the PLA / CB improve one order of magnitude, the tensile strength and fracture elongation were maintained at 45MPa and 100% or more, having a good application prospect. In addition, CB Add effectively inhibit the migration of plasticizers and water vapor permeability in the blend system.

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