Effect Of Kneading Modification Of Montmorillonite On Starch Based Biodegradable Film

In this paper, quaternary ammonium salts which been dissolved by 50% ethanol were used as modifiers to make a single modification and compound modification of montmorillonite by kneading method. And each modified montmorillonite was mixed with hydroxypropyl distarch phosphate (HPDSP) as an enhancer to prepare starch nano-composite films by extrusion blowing system. The nano-structure and the molecular interaction of the modified montmorillonite were detected by X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Mechanical properties analysis, scanning electron microscopy (SEM) and contact angle test and water vapor transmittance (WVP) were been used to detect the effects of single modifier modified montmorillonite on starch nanometer composite films and influence of different composite modified montmorillonite content on starch nanometer composite films. The main results were as shown:(1) It had been confirmed that long chain quaternary ammonium salts achieved modify the montmorillonite by kneading method.Dl 821 was performed the best on intercalation and exfoliation the layer system which enlarged the d-space to 2.79nm and lower the CEC to 86.2 mmol/100g. The alkyl chain number, chain length and benzyl groups played different roles in the kneading process and led to the various characters of the organic montmorillonite which had been proved by the XRD, TEM, and TGA.(2)OMMT promoted the compatibility of HPDPS and MMT effectively, and improved the mechanical properties and water resistance performance of starch film. Among each group of starch/OMMT film, Starch/D 1821-MMT film had a good performance that tensile strength was 6.14MPa, Elongation at break was 50%, WVP was 3.26×10-10g·m-2·s-1·Pa-1. Under the condition of single modifier modified montmorillonite as enhancer, the d-space of the OMMT has a positive connection with the performance of the starch film. And different OMMT brought the starch film various characters, such as the elongation at break of 1227-starch was 129.31%.(3)Achieved the experiment design that modified montmorillonite by two kind of quaternary ammonium salts, and composite organic montmorillonite was prepared by the composite modifiers. By analyzing the results, it was confirmed that there was no connection between composite organic montmorillonite characters and the addition order of modifiers. The appropriate composite modifiers content was 30% when the two kind of quaternary ammonium salts ratio was 1:1. Compared to the single modifier OMMT, the composite organic montmorillonite had a new layer sequence which the d-space was 5.31nm.(4) When the CMMT content reached 12.5%, the tensile strength of starch/CMMT film reached the best level,4.0MPa, and elongation at break was 20.4%, WVP was 3.32×10-10g·m·m-2·s-1·Pa-1. Compared to the characters of the starch film with single modifier organic montmorillonite, there was an obvious deterioration of the starch/CMMT film characters. Although the compatibility was raised by this disordered layer structures, it hindered the enhancement effect and blocking effect of montmorillonite to starch film, lead to a fall of the corresponding properties of the starch fill.