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Study on Structure and Properities of Nanocomposite Based on Konjac Glucomannan Nanocrystal

Author: HuangJin
Tutor: GaoShanJun
School: Wuhan University of Technology
Course: Materials Science
Keywords: Konjac glucomannan KGM nanocrystal Chitosan Sodium alginate Nanocomposites
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 170
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Abstract

Because the fossil resources such as petroleum,coal and so on,are being exhausted increasingly,and the problem of environmental pollution from the waster and litter of nondegradable polymer materals that are mainly derived from petrolrum resources becomes more and more serious.Therefore the polymer science and technology faces a new challenge.Nowdays,research and exploitation of new materials based on natural polymers have become the front of polymer science.It is a good way to reinforce material that nano-sized structure uniformly dispersed into polymer matrix by strongly interacting with matrix and restricting the motion of polymer segments.Inorganic nanoparticles from fossil resources have been successfully applied to polymeric nanocomposite materials.Compare to these abio-nanoparticles,the stably nanocrystals structure(eg.Cellulose and chitin nanocrystals and starch nanocrystals) got from polysaccharide of propagation after acid hydrolysis after sonication,had excellent properites with biodegradable, chemically modified and so on would drawn more and more attention in view of their environmental friendliness to the earth.Konjac Glucomannan(Abbr.KGM) is the special resource in China,which is a kind of natural polymers.It is innocuous and biodegradable.Generally speaking,the molecular weight of KGM can reach to the order of magnitude of 10~6.This work aims to produce potential nanocomposite material with high mechanical properties mainly based three natural polymer,chitosan(Abbr.CS),sodium alginate(Abbr.SA) and KGM nanocrystal.The content of this thesis is divided into two aspects:after acid hydrolysis after sonication etc method to dispersion,the one is KGM nanocrystal can be got from the disruption of KGM.And the other is the nanocomposites based on KGM nanocrystal.The detailed work in this thesis is described as follows.KGM nanocrystal got from the disruption of KGM by acid hydrolysis was characterized by transmittance electron microscope(TEM),laser particle size analyzers, X-raydiffraction(XRD),Infrared spectroscopy(IR spectroscopy) etc.Meanwhile,the KGM nanocrystal was filled into matrix to produce full-degradable nanocomposite.In addition,in order to disclose the structure-mechanical properties relationship,such nanocomposite materials were characterized by X-ray diffraction(XRD),differential scanning calorimetry(DSC),scanning electronmicroscope(SEM),and tensile test etc. In this study,we get the preparation of aqueous suspensions of KGM nanocrystals in the optimize way.We have determined the operative conditions leading to the smallest size of insoluble hydrolyzed residue within the shortest time and with the highest yield.The KGM nanocrystal,derived from natural Konjac Glucomannan granule,was also used to prepare CS and SA nanocomposite,and produce reinforced full-degradable nanocomposites.It was attributed to a uniform dispersion of small-scale KGM nanocrystal in amorphous region of matrix as well as enduring stress of rigid KGM nanocrystal and stress transferring mediated with interfacial interactions between active KGM nanocrystal surface and matrix,which enhances the strength and elongation at one time.Based on the study above mentioned,the strength of CS film and SA film were enhanced by introducing nanoparticles.At the same time, the water-resistance of CS film was also improved to a certain extent.Moreover,it is disclosed that the mechanical properties of nanocomposites strongly depend on the shape,size,surface character of nanoparticles and their distribution in polymer matrix.There are always three kinds of interaction which contribute to the strength of nanocomposite and even elongation,such as original interaction in polymer matrix,the interracial interactions between matrix and nanoparticles,and the self-aggregated affinity among nanoparticles.In conclusion,the structure-properties relationships for these systems are established while a strategy to design full-degradable nanocomposites has been submitted.

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