| This application adopted dry method to synthesize Maleic Anhydride Acetic starch(ES). The effect of reaction time, temperature, water content and ratio of reactants onstarch substitution was investigated. As a result, when content of water was between12% and 14%, the weight ration of anhydride to starch was between 3/10 and 4/10, under85℃-90℃and 2h—3h of reaction time, the substitution of esterified starch could reach0.4, and the efficiency of available lime of Anhydride reached 75%。ES wascharacterized by Infra-red spectrum, and its characteristic adsorption of carboxylvibration was found; The esterified starch was compared with starch in hydrophiliccharacter, viscosity, thermal performance, and the result showed that esterified starchwas better on hydrophobe, lower viscosity, and better thermal stability.The ES/PCL blend was manufactured by extruding, and its properties was detectedby Capillary rheometers. The result showed that non-Newton index (n) for melting blendswas less than 1, and pseudoplastic was exhibited. Under the same Shear stress, the higherthe content PCL was, the lower apparent viscosity was. All apparent viscosity was lowerthan that of TPS. Within the process temperature range, the apparent viscosity of blendsdecreased and the shear rate increased as the temperature increased; Under certaincircumstances, Eηof several blends was within the range of 47 KJ·mol-1to 53 KJ·mol-1.Additionally, with the increase of the content of PCL, the apparent viscosity decreased.The apparent viscosity and thermal stability were investigated by DSC and TG. Thepeak temperature and thermogravimetry of the blends was between that of esterifiedstarch and PCL. It implied that there were interactions among the polymers. Thecomplatibility and thermal stability of the blends were improved.The water tolerance was studied for the blends sheet materials processed by flatpress cure machine. The result indicated that the water tolerance of sheet materials wasimproved significantly by PCL. As a whole, the water tolerance of sheet materials wasadvanced in company with the increase of the concentration of PCL. The waterabsorption of some sheet materials was only 3%. However the dosage of water andglycerin had an impact on the water tolerance of sheet materials. The water absorption ofall the sheet materials were lowered than 20% when only glycerin acted as the plasticizerand were up to 160% when only water acted as the plasticizer in the system. The watertolerance was between 20%-160% when the mixture of water and glycerin acted as the plasticizer. In addition, the waterproof ability and size stability of ES(m)/PCL(m)=70/35 series samples were better than that of 70/8, 70/26 and 70/49.The mechanical properties of the blends sheets were determined by the electronuniversal testing machine controlled by microcomputer. The result demonstrated that thetensile strength and breaking elongation of ES/PCL blends sheets were higher thanthose of thermoplastic starch. The mechanical properties were satisfactory with thebreaking elongation of 97%, fracture strength of 177 MPa in the blend system of 70gfixed esterified starch, 5g-25g water, 10g-25g glycerol and PCL of 8g-35g with water andglycerol as plasticizers.The degradation properties of ES/PCL sheets were studied by the experimental ofsoil-burying. The result indicated that the degradation of blends sheets was speeded upwith 50% loss of weight in 30d, 70% loss of weight in 60d. All the sheets were degradedentirely in soil and these could be considered as ready biodegradable materials.
|
PDF Full Text Request