Synthesis Of Hydroxyalkylformamides And Study On The Properties Of Thermoplastic Starch Using Hydroxyalkylformamides As Plasticizers

Starch, a cheap polysaccharide obtained from a great variety of crops, is one of biomass resources. Thermoplastic starch (TPS) can be obtained from starch in the presence of plasticizer. TPS is a promising biodegradable plastic. It is one of key research projects to improve the properties of TPS.In the text, a series of hydroxyalkylformamides (HAF) were synthesized from alcohol amine and ethyl formate without solvent and catalyst. These products were confirmed by FT-IR, 1H NMR, MS. There were no catalyst, no high pressure and no use of much solvent for the method compared to traditional method. The new method reduced the amount of superfluous reagent. It accorded with the principles of green chemistry.Thermoplastic starches using nontoxic HAF as plasticizers (HAFTPS) were prepared. The properties of HAFTPS were studied. The hydrogen bond interaction between HAF and starch was proved by Fourier-transform infrared (FT-IR) spectroscopy, it demonstrated that starch and HAF had good compatibility. By scanning electron microscope (SEM), starch granules were completely disrupted and a continuous phase was obtained. The crystallinity of HAFTPS was characterized by X-ray diffraction (XRD). The HAFTPS crystallinity related to the structure of plasticizer HAF. If there was one hydrogen atom connected to nitrogen of HAF, the corresponding HAFTPS only had VA crystallinity; if there was no hydrogen atom connected to nitrogen of HAF, the corresponding HAFTPS had EH crystallinity due to the bulky plasticizer. VA and EH crystallinity could lead to VH crystallinity upon hydration. The properties of HAFTPS were compared with that of traditional thermoplastic starch using glycerol as plasticizer (GTPS). The thermal stability of HAFTPS was inferior to that of GTPS. HAFTPS water vapour absorption and mechanical properties were investigated. The water resistance of thermoplastic starch using N,N-bis(2-hydroxyethyl)formamide as the plasticizer (BTPS, one kind of HAFTPS) was better than that of GTPS, the water resistance of other prepared HAFTPS was inferior to that of GTPS. At relative humidity (RH) 44%, the tensile strength of BTPS was better than that of GTPS, whereas, the tensile strength of other HAFTPS was inferior to that of GTPS. At RH 68%, the elongation at break of BTPS was better than that of GTPS.HAF were used as Montmorillonite (MMT) activators. MMT-reinforced HAFTPS/MMT nano composites were prepared with the method of one time extrusion. The hydrogen bond interaction among HAF, starch and MMT was proved by FT-IR, it demonstrated that starch, HAF and MMT had good compatibility. Exfoliated nano MMT in HAFTPS/MMT was found by atomic force microscopy (AFM). XRD demonstrated that d-space of MMT in HAFTPS/MMT was expanded. MMT had no influence upon the crystallinity HAFTPS. The thermal stability was examined by Thermogravimetric (TG) analysis. The water resistance and tensile strength of HAFTPS were improved by adding MMT.