Study On The Preparation And Performance Of CNC/PVA Composite Gel

This article introduced the background,theory of the gel,PVA and CNCs propetrties andits application. The nanofibers manufactured through Chemical purification and ultrasonicdegradation method. Using PVA as the base material, which was improved by chemicalcrosslinking,compositing natural polymer CNCs as reinforcement produced PVA／CNCssurface porous structure compound hydrogel, and studying the hydrogel swelling andmechanical properties, as well as the Image pro plus software were to analyze the pore size anddensity of the porous aerogel. The paper also uses FT-IR, TMA and SEM studyed the propertytransformation mechanwasm of nanocomposite gel. Conclusions based on thwas research wereshown as following:1. Taking the medical degreasing cotton was the main raw material for the preparation ofnanocellulose by chemical and mechanical processing. Transmittance performance of thesuspension was studied at different process, at the same time the chemical treatment groups andnanofibers diameter range were observation by FT-IR and SEM, respectively. Eventually, thebetter preparation method was obtained: chemical processing, grinding and homogene by thehomogenizer, after that the nanofibers can be obtained in less than one hundred in diameter.2. To generate free radicals on the surface of nanofibers was using of chemical methods,and then the crosslinker made the nanofibers, polyvinyl alcohol, acrylic acid producingchemical cross-linking to form a dual-network structure. The performance of hydrogel werestudyed, found that the swelling ratio (SR) of hydrogel increased with the increase of pH value,however, decreases with increase of temperature. But the swelling ratio was reduction when thetemperature and pH value were Dual role3. The paper studyed the influencing factors of mechanical properties of hydrogels byone-time compression test and the fatigue/creep test at different experimental conditions.Results showed that the mechanical properties of nanocomposite hydrogel, were improvedsignificantly. When the fiber content was greater than7.1%, the increased amount ofmechanical properties were the most obvious. When the fiber concentration was greater than5.4%, the hydrogel could recovery completely after mechanical tests. It proved that higherfibers content was contributed to shape recovery of hydrogel after tests. In the case of thehigher fibers content, the greater impact in compression properties of the composite hydrogelby temperature composite hydrogel; And hold time had a certain influence on the fatigue/creep.4. Preparation of aerogels by freeze-drying method cross-sectional was the smoother, but side was a gully; The morpHology was showed by SEM, pure PVA aerogel was almost no pores,to the contrary, the composite airgel has more pores, and pores planar were approximatelyhexagonal, fibers were wound in the sidewall or penetration the pores. The average pore areawas proportional to the fiber content, but the porosity was contrary. The thermo-mechanicalanalysis: glass transition temperature of aerogel was proportional to the nanofibers content.5. The three-dimensional network of gel was formed by three substances cross-linked witheach other. The vibration of the groups was weakened by FT-IR as increasing fibers content; itproved that the nanocellulose can make the system better chemical stability.