Study On Konjac Glucomannan Composite Materials Preparation

Nowadays,the petroleum and coal resources are being exhausted gradually and the environmental pollution from the deposit of non-biodegradation synthetic polymers is becoming more and more serious.Therefore,it is necessary to study and develop the novel polymer material mainly from natural polymer.Konjac is a kind of agricultural product with high yield.It is widely planted in the mountainous areas in south China with low cost.Konjac Giucomannan(KGM)is the main content of the Konjac.KGM has the similar structure to cellulose,but has the water solubility that is not embodied by cellulose.The abundant hydroxyl groups in KGM molecules are high active, and it contains certain amount of acetyl groups,so that KGM is easy to be modified by various technology.The main contents and conclusions in this paper are as follows:1.Graft copolymerization of 4-vinylpyridine(4-VP)onto KGM in an aqueous medium initiated by Ammonium Persulfate can be carried out with satisfactory results.It is generally believed that Ammonium Persulfate which initiates polymerization of vinyl monomers onto water-soluble polysaccharides cannot reach a high graft ratio in aqueous medium.However,by using ethanol as dispersant,4-VP is dispersed effectively in deionized water,and phase conglomeration is hindered effectively,graft copolymers with high grafting efficiency and grafting percentage have been obtained.The optimum Grafting ratio(G%)and grafting efficiency(E%)have achieved 307.27% and 52.75%respectively,and the optimal parameters are under[KGM]=1.00g/L,[APS] =1.00×10^-2mol/L,[4-VP]=9.32×10^-2mol/L,[H⁺]=5.00×10^-2mol/L,temperature =35℃,time =120min.Proof of grafting was obtained from gravimetric estimation and IR analysis.Grafted production was thermally more stable than pure KGM on the basis of the TGA results.The elementary research of the adsorption capacity for heavy metal suggested that the copolymer could be used as sorbent commendably.2.A novel high performance and biodegradable blend film of konjac glucomannan(KGM)and lignin(LIG)was prepared successfully by using the solvent-casting technique with different blending ratios of the two polymers.Their structure and properties were studied by Fourier reflectance infrared(FIR),X-ray diffraction(XRD),scanning electron microscopy(SEM), thermogravimetric analysis(TG,DSC),tensile tester.The results indicated that the blend system of konjac glaucomannan and lignin had good miscibility.The IR spectra of the blends proved that hydrogen-bonding interaction occurred between KGM and lignin.The crystal melting temperature(T_m)of these blends increased with an increase of lignin content,which indicates that these blends are able to form a miscible phase due to the formation of intermolecular hydrogen bonding between the KGM and lignin.The thermostability of these blends increases with the increase of lignin content.At a 5%lignin incorporation level,the maximum value of 70.13MPa tensile strength was reached and the blend exhibited its maximum value of 60.46%strain.When the threshold in lignin content for blends exceeded the range,the tensile behavior of these blends became poorer because of micro-domains of lignin.3.Konjac glucomannan(KGM)films with different plasticizer(glycerin,Sorbitolum,citric acid) were prepared successfully by using the solvent-casting technique.Their structure and properties were studied by X-ray diffraction(XRD),thermogravimetric analysis(DSC),tensile tester.The results indicate that the glass transition temperature(Tg)of films decrease with an increase of plasticizer content,when the ratio of plasticizers are the same,the decline degree of Tg:citric acid＞Sorbitolum＞glycerin,the ability of plasticizers to plasticize KGM films:citric acid＞Sorbitolum＞glycerin.when the ratio of glycerin,Sorbitolum,citric acid are 25%in films,breaking elongation(ε_b)increase 57.36%,72.28%,44.99%than pure KGM film respectively,tensile strength(σ_b)decrease 48.43%,44.58%,16.42%accordingly.Glycerin,Sorbitolum,citric acid all can improve breaking elongation(ε_b)and reduce tensile strength(σ_b)of KGM films.For the property of the three plasticizers is distinct,the ability of plasticizers to plasticize KGM films is variant.Citric acid is preferable to other plasticizers,it can not only improve breaking elongation(ε_b)but also reduce tensile strength(σ_b)lesser.