Studies On Preparation And Properties Of Polymer/Clay Nanocomposites

Polymer/clay nanocomposites combine the properties of organic polymers and inorganic nanoclay,exhibit excellent versatility and extremely high application value,and have become a research focus in recent years,but due to the poor compatibility of clay and polymer,there were problems such as how to realize the directional arrangement of clay to solve the dispersibility.In this work,a series of polymer/clay nanocomposites were prepared by combined waterborne polyurethane(WPU),polyvinyl alcohol(PVA),and thermoplastic polyurethane(TPU)with organically modified MMT.The main research was as follows:1.The WPU/AS-MMT nanocomposite emulsions,nanocomposite films and coatings were prepared from WPU and MMT modified with Aminosulfonates(AS)by prepolymer emulsification.The effect of different AS-MMT content on the particle size of the emulsions,the morphology,mechanical properties,heat resistance,water resistance of the nanocomposite films and the gas barrier properties of the nanocomposite coatings were discussed in detail.The results of SEM and XRD showed that AS-MMT was uniformly dispersed in the nanocomposite films,and gradually forms a regular directional arrangement in WPU with the increase of AS-MMT content;the tensile test results showed that the tensile strength and Young's modulus of the WPU/AS-MMT-60 wt%nanocomposite film were increased to 62.45 MPa and 9.82 GPa respectively;the water absorption rate of the nanocomposite film drops to 2.23%when the AS-MMT content was 70 wt%;The water vapor transmission rate(WVTR)and oxygen transmission rate(OTR)of WPU/AS-MMT-50 wt%nanocomposite coating reached 2.68g/(m~2·day)and 26.71 cm~3/(m~2·day·bar),respectively,which were 73.3%and 46%lower than pure WPU.2.The PVA/AS-MMT nanocomposite films and coatings were prepared by dissolved and blended PVA in the AS-MMT aqueous dispersions,used solution evaporation and vacuum filtration methods,respectively.The results of ATR-FTIR showed that AS-MMT successfully formed hydrogen bonds with PVA through the amino and sulfate;the results of SEM and XRD showed that AS-MMT was highly oriented in the nanocomposite films,and AS-MMT was further intercalated and exfoliated by the PVA;the tensile test results showed that the mechanical properties of nanocomposite films prepared by the vacuum filtration method better than the solution evaporation method,and when the AS-MMT content was 40 wt%,the tensile strength and Young's modulus of the nanocomposite film can reach 147.85 MPa and 8.18 GPa,respectively,which were increased to 2.76 times and 10.23 times compared with pure PVA;the barrier performance results showed that the WVTR and OTR of the nanocomposite coating can be reached to 4.64 g/(m~2·day)and 0.82 cm~3/(m~2·day·bar).3.The TPU/OMMT nanocomposite films were prepared based on TPU and self-made cationic waterborne polyurethane modified MMT by solvent blending method.The OMMT's effect on the morphology,mechanical properties,heat resistance,water resistance and transmittance of nanocomposite films were investigated.The characterization results showed that OMMT had good compatibility with TPU,and was in a uniform and completely peeled dispersion state in TPU matrix;When the OMMT content was 3 wt%,the tensile strength,modulus and elongation at break of the nanocomposite film reached 64.05 MPa,17.41 MPa and 887%,respectively,which were 67.3%,59.6%and 20%higher than pure TPU,achieved both strengthening and toughening.The water absorption rate of the nanocomposite films was reduced to 1.6%,and the light transmittance of the nanocomposite films remained above 80%when the OMMT content was less than 5 wt%.