Study On Preparation And Application Of Cellulose Nanocrystalline/Inorganic Nano Phase Hybrid Materials

Cellulose is a kind of natural degradable material widely existing in nature.Nanocrystalline Cellulose(NCC)have high strength and modulus which can be used to reinforce polymer matrix composites.However,due to its high polarity and specific area,NCC is easy to agglomerate in the process of rubber processing.Also the preparation of NCC is complex and high cost.The reasons above have limited its application.In this thesis,a cellulose aqueous solution(CEL)was prepared by a lowtemperature alkali / urea system,and then NCC / NR composites were prepared by insitu dispersion of NCC in natural rubber latex(NRL)respectively with the methods of co-coagulation and in-situ precipitation.Then,based on the sol-gel technique,the precipitated cellulose was hybridized with zinc nitrate to prepare NCC-ZnO hybrids,and different hybridization processes were used to control the precipitation morphology and particle size of the hybrids.The mechanical properties of the composite materials and micro-morphology observation were used to characterize the reinforcing effect of NCC and NCC-ZnO hybrids on natural rubber and its morphology in the matrix.The co-coagulation method is to dilute the CEL with water and drop it into the NRL drop by drop.During the demulsification process of the NRL,the NCC is co-coagulated in the rubber matrix.Highest mechanical properties was prepared by CEL diluted with deionized water to three times the original mass at 10 ?.The 3phr NCC could significantly improve the tensile properties and tearing properties of vulcanizates;SEM photos show that Sheets or rods were distributed in the matrix.The in-situ precipitation method is to make NCC precipitate in its aqueous solution,and then drop it into NRL and use dilute acetic acid to demulsify to prepare NCC / NR composite material.When the precipitation temperature was 30? and the CEL was diluted twice,the prepared composite material had the best mechanical properties.At this time,NCC was dispersed in the rubber in the form of 200-300 nm spheres.During the precipitation of cellulose,zinc nitrate was added to precipitate ZnO under the induction of cellulose to prepare a cellulose/ZnO hybrid.The hybrid material presented a rod-like structure with a diameter of 1.5 ?m and a length greater than 20 ?m.The cellulose/ZnO hybrid could accelerate the vulcanization speed of natural rubber,effectively increased the vulcanization speed of rubber,improved the mechanical properties such as tensile strength and tear strength of natural rubber.