Optimization Of Nanocrystalline Cellulose Preparation And Study On Natural Rubber Reinforcement

Since carbon black?CB?has been found can be used to reinforce rubber,this petrochemical product has always occupied the first place in rubber filler consumption and reached to half of total rubber consumption.It is well known that petrochemical resources will be draining out in the near future,so we have to found a filler that can replace carbon black reinforcing rubber.The annual output of cellulose can reach 10¹¹ tons.Since the nanocrystalline cellulose?NCC?prepared by cellulose has been discovered.Its'advantages of high modulus,degradable,high specific surface area,good biocompatibility have attracted the favor of a large number of scientists.Because of its'strong chemical polarity,it dissolves badly in long chain weak polarity rubber phase.The poor capacity leads to the slow development of the industrialization process of large-scale use of nanocrystalline cellulose to reinforce rubber.Silane coupling agent is a kind of auxiliary agent that has shown its great economic value in industrial production.Its'silicon-containing end group can reactive with the polar filler,and the other end chain contains a group which is compatible or reactive with the matrix,making it a polar filler and a non-polar bridge between the substrates,so it can promote the dispersion of the filler in the matrix.3-Octanoylthiopropyltriethoxysilane?NXT?is a kind of silane coupling agent which is developed to solve the problem of agglomeration due to the presence of a large amount of silanol on the surface of silica.In view of the large amount of reactive hydroxyl groups on the surface of cellulose and silica,we use NXT to graft nanocrystalline cellulose.In this thesis,NCC was prepared by bleaching eucalyptus pulp through modified ammonium persulfate and hydrogen two-step oxidation step.Then carbon black was partially replaced by NCC to prepare natural rubber?NR?/CB/NCC composite.We compared it with the pure carbon black reinforcing rubber system to explore the mechanism of NCC and carbon black synergistic reinforcement and the possibility of NCC replacing carbon black,we found that the process performance of the rubber which mixed with NCC is better,and the vulcanization time of the rubber compound also has down.The time consumption is beneficial to reduce the energy consumption in industrial production.With the increase of NCC content,the Payne effect of the system is weakened,the compression fatigue temperature is gradually reduced,and the tear strength and tensile strength can be maintained at 5 phr.And then mechanical properties began to decline significantly.The hydrolyzed NXT silane coupling agent is mixed with NCC suspension to react the hydroxyl groups on the two phases to obtain modified nanocrystalline cellulose?XNCC?.The Zeta potential of the modified cellulose surface is increased by comparison with NCC.The particle size is further reduced.Compared with the NR/CB/NCC system,the processing performance of NCC replaced by XNCC is further improved,the vulcanization time is further reduced,and the Payne effect of the system is further reduced.The performance is optimal at10 phr,and DMA test shows that the NR/CB/XNCC system has lower rolling resistance at the same time.