Study On Crystallization Behavior And Flame Retardancy Of Natural/eucommia Ulmoides Rubber

Natural rubber(NR)as a kind of natural macromolecule polymer,normal temperature have good elasticity,abrasion resistance and excellent dielectric properties,but as a result of NR resources in China is relatively poor,already can’t meet the needs of the development of rubber,rubber blend as one of the best ways to solve such problem,by more and more attention.EUG has become the preferred material to replace NR because of its duality.However,NR/EUG using rubber(BR)also inherited the lack of flame retardant performance of traditional rubber materials,which seriously restricted the use of BR.The use of green and environment-friendly bio-based flame retardant rubber material has become the focus of current research.Taking BR as the main research object,this paper explores the combustion,mechanics and crystallization behavior of flame retardant BR composites through the interaction between bio-based flame retardant and BR.The main research contents and conclusions of this paper are summarized as follows:In this thesis,NR and EUG were blended to get NR/EUG and rubber(BR),and CS and APP were added to NR,EUG and BR in a certain mass ratio to form flame retardant rubber material(FRBR).It was found by differential scanning calorimetry(DSC)and X-ray photoelectron spectroscopy(XPS)that the addition of flame retardants reduced the crystallinity of FRBR significantly.LOI,UL-94,SEM and other tests showed that crystallization in FRBR would reduce the binding ability of rubber crosslinking relative to flame retardants,resulting in uneven distribution of flame retardants and reducing the flame retardancy efficiency of flame retardants.Meanwhile,mechanical tests showed that adding flame retardants would reduce the mechanical properties of FRBR blend system.In order to improve the efficiency of flame retardant,using sodium tripolyphosphate(STPP)as core material and chitosan(CS)as wall material,microcapsules CS@STPP were prepared by ionic gel method.The morphology,chemical structure and thermal properties of the microcapsules were characterized by SEM,FTIR and TG.CS@STPP and expandable graphite(EG)were added to BR in a certain proportion to investigate the synergistic effect of CS@STPP and EG on the flame retardancy of BR.Through LOI and VERTICAL combustion(UL-94),it is found that when m(CS@STPP)∶ M(EG)= 4∶1,the flame retardant effect of prepared FRBR is the best,which is attributed to the synergistic effect of CS@STPP and EG to the formation of more stable and compact carbon layer structure,better continuity.In addition,The combustion performance of FRBR 5 was significantly reduced,with LOI reaching 28.4% and UL-94 reaching V-0rating,and the maximum heat release rate decreased by 30%.In order to reduce the influence of biological flame retardant CS@STPP on BR,the flame retardant reinforced integrated rubber composite(FROR)was prepared by chemical bonding between epoxidation natural rubber(NRO)and CS@STPP.Hydrogen nuclear magnetic resonance(HMR)and Fourier transform infrared spectroscopy(FTIR)showed that FROR was successfully prepared.The flame retardant test results showed that the influence of flame retardant on FROR was significantly reduced,the limiting oxygen index reached 28.2%,UL-94 grade was V-0 grade,and the maximum heat release rate decreased by 35%.At the same time,the chemical bond between flame retardant and BR makes the elongation at break of FROR reach 590%,and the mechanical properties of FROR are obviously improved.