Preparation And Mechanism Of Antibacterial NCC/PEG Composite Phase Change Materials

As the worsening of contemporary energy crisis and environmental pollution, the searchs for renewable new energy material become current research trend. Cellulose constitute the reserves more abundant in the nature and the sustainable of renewable resources, nanocrystalline cellulose (NCC) not only possesses all the characteristics of the fiber, also with many advantages of nanomaterials, based on its good performance, preparing more new nano materials with phase change, bacteriostatic and other performance is one of hot spot in current research in the field of nanocrystalline cellulose.Reed pulp as raw material, this paper used the ultrasonic pretreatment beafore acid hydrolysis of nanocrystalline cellulose (NCC),and on the basis of single factor experiment, three main influencing factors on the yield of NCC has carried on the response surface optimization. Characterized by transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR), laser particle size instrument (DLS), and so on. The samples are in the rules of morphology, uniform particle size distribution of type I nanocrystalline cellulose. Sulfuric acid hydrolysis of NCC prepared by response surface analysis of the optimum process conditions is:the raw material first pretreated32.12min with ultrasonic and then to the concentration of53.46%sulfuric acid hydrolysis in the constant temperature water bath of52.28℃for4h, and the highest rate of NCC (78.64%) was obtained.Using three different raw materials for the preparation of nanocrystalline cellulose with different particle size distribution as reinforcing agent, different m(NCC)/m (PVA) composite membrane was prepared by blending method, and its mechanical properties and thermal properties was studied. The results showed that three kinds of raw material prepared three different length to diameter ratio of NCC. Enhancement effect of the mixed membranes showed under NCC with different size adding in the different mass ratio.Silver nanoparticles were synthesized in situ adsorption on the surface of NCC that was used as stabilizing agent. Through TEM, XRD, UV, TG and filter method bacteriostatic experiment,the NCC/silver nanoparticles sol had been characterized, and the results showed: in the m (Ag)/m (NCC) for3%～5%was the optimal preparation conditions and the silver nanoparticles in NCC/silver nanoparticles dispersed evenly and spherical with the particle size10nm,which was mainly adsorbed on the surface of nanocrystalline cellulose; NCC/silver nanoparticles sol has antimicrobial properties, when the particle concentration was0.001mol/L, it was best for the inhibition of Escherichia coli. and when silver particles concentration was about0.0006mol/L, it was best inhibition effect of Staphylococcus aureus; The smaller the particle size of silver nanoparticles the inhibition to E.coli and S. aureus was much better. With nanocrystalline cellulose (NCC) as the skeleton, polyethylene glycol (PEG) as the function of phase transition, solid-solid phase change materials of NCC-PEG was obtained by chemical grafting method. Technical means such as IR, DSC, TGA were used respectively to NCC-PEG phase change materials for thermal behavior as well as the energy storage performance characterization. Results showed that the preparation of the NCC-PEG phase change materials by chemical grafting was successful, and it effectively improved the thermal stability of phase change materials, which was up to150.1J/g with efficiency energy storage.