Studies Of Thermoplastic Konjac Glucomannan Composite Resin

Petroleum-based synthetic polymer materials have faced two majorproblems, which are oil resources exhaustion and its seriousenvironmental pollution from litter of nondegradable polymer material s.Therfore the most effective way to solve those two problems is to find arich source of the biodegradable natural polymer materials, which cansatisfy people’s demands after being modified in physical or chemicalmethods.Konjac glucomannan (KGM),is one of the richestbiodegradable natural polymer polysaccharides, and is a uniqueresource in China’s Middle West region.This article centers arounddeveloping the novel KGM-based materials which is environmentallyfriendly and can satisfy people’ s dema nds. The raw KGM is made intoTDKGM b y grafting modification. The TDKGM/PCL composite resin andthe TDKGM/PBS co mposite resin have been fabricated by meltblending of TDKGM and polycaprolactone（P CL） and polydiethyleneglycol sebacate (PBS), and their me chanical properties as well asther mal properties have been investigated. The results were concludedas follows:(1) Thermoplastic deacetylated konjac glucomannan (TDKGM)was synthesized by free radical graft copolymerization of met hylacrylate (MA) onto the backbone of deacetylated konjac glucomannan.The structures of the TDKGM ha ve been characterized by FTIR、 DSCand DMA. In the IR spectra of TDKGM, the disappearance of peaksat1631cm-1and3386c m-1was due to the reason that the–OH groupsof the KGM reacted with MA. It can be seen that the C–H bending at1437c m-1the–CH2–bands were appeared in the TDKGM, indicatingthat the KGM has grafted with MA or the polymerization of the MA.Theresult of TG shows that the decompos ition temp erature of the TDKGMis higher than the KGM by140℃,reaching aound396℃. And ther e s u l t o f DSC and DMA shows that glass transition temperature appearedat14℃, then the TDKGM is Thermopl astic polymer. (2)The TDKGM/PCL composite resin have been fa bricated withdifferent polycaprolactone (PCL) contents by using melt blending, andtheir mechanical properties as well as thermal properties have beeninvestigated. The results of DMA show that the storage mo dulus of theco mposite can be enhanced markedly co mpared with TDKGM byincreasing the PCL contents in the composites resin, but the glasstransition te mperature (T g) doesn’t change significantly. With theaddition of50wt%PCL (PCL50), the therma l deflectiontemperature(HDT),the initial decomposition temperature and the VicatSoftening Temprature(VICAT) increase by38.6℃、20℃and16.6℃respectively, compared to the pristine TDKGM sample. The mecha ni c altesting shows that the tensile strength of the T DKGM/PCL compo siteresin and elongation at break can be improved constantly by increasingthe PCL contents in the composites resin, and the PCL50has a veryhigh elongation at break of580.61%as compared with282.85%for purePCL, while the tensile strength remains as high as9.49MPa.(3)The TDKGM/PBS composite resin have been fabricated withdifferent polydiethylene glycol sebacate (PBS) contents by using mel tcompound method, and their mechanical properties as well as thermalproperties have been investigated.The result of the SEM shows that theTDKGM/PBS blending systems is separated, which can be clearly seenby scanning electron microscopy of PBS40, and its elongation at breakis only125.58%. PBS conten t is50%, while the te nsile strength of thePBS50is18.15MPa, and elongation at break of232.15%.With theaddition of50wt%PBS (PBS50), the thermal deflection temperature(HDT), the VICAT and melt flow rate (MFR) are86.8℃,96.3℃and12.8g/min respectively. The results of DMA show that the storag emodulus of the composite can be enhanced markedly compared withTDKGM by increasing the PBS contents in the composites resin, andthe glass transition temperature (T g) reduces slightly. The results ofDSC show that the cr ystallization temperature of the TDKGM/PBScomposite resin is much higher than that of PBS, but the melting Pointdoesn’t change significantly. Initial decomp osition temperature is enhanced by increasing the PBS contents, so the TDKGM/PBSComposite resin has a good thermal stability(4) The TDKGM/PCL co mposite resin and the T DKGM/PBScomposite resin have good mechanical property and liquidity. TheTDKGM/PCL composite resin and Th e TDKGM/PBS composite resinare processed by blow molding, then preparing biodegradableTDKGM/PCL and TDKGM/PBS new fil m and boards which boast goodmechanical properties, and they can replace non-degradable plastic insome areas. Those properties are of great significance to addressingenvironmental problems, utilizating Konjac glucomannan resource anddeveloping new materails.