Formation And Enhancement Of Sacrificial Network Formation Driven By Facile Interfacial Interactions

Natural rubber(NR)has excellent mechanical properties.The Previous studies attribute the excellent performance of NR to its molecular chain structure:(1)High cis-polyisoprene of NR chain;(2)Natural network structure formed by the terminal groups of NR molecular chain and combined non-rubber component(NRC).Although,the molecular chain structure of the synthetic polyisoprene rubber is similar to that of NR,its performance is still not comparable to that of NR,which indicates that the molecular chain structure is not the only reason for the excellent mechanical properties of NR.Researchers neglect the contribution of free NRC to the properties of NR in the feature of structure-component-property studies of NR.Therefore,exploring the effect of free components on the excellent mechanical properties of NR can further understand the reasons for the excellent mechanical properties of NR and optimize the processing technology of localized high-performance NR.To understand the effect of free NRC on NR matrix,this article analyzes the interfacialinteraction between free NRC(amino acids)and NR molecular chains.The formation mechanism of the sacrificial bond network constructed by the interfacial interaction between amino acids and NR molecular chains,The effect of such sacrificial network on the mechanical properties of NR.(1)Influence mechanism of natural sacrificial network on the mechanical properties of NRTEM is used to observe the changes of free NRC in morphology of NR and purified natural rubber(CNR)after high-speed centrifugation.The free NRC disappears after the removal of free NRC by high-speed centrifugation.Though DSC curves at different heating rates of NR and CNR,it is found that free NRC can participate in the crosslinking process and react with rubber chain,resulting lower activation energy.Though energy dissipation and fracture energy of NR and CNR,it is found that free NRC in the NR matrix can construct a sacrificial network which preferentially ruptures upon deformation to dissipate energy,leading to the increase in toughness.Moreover,some NRC can participate in the crosslinking process and act as the effective crosslinking points,which further improves strength and toughness.(2)Research on the interfacial interaction between amino acids and NR molecular chains After the addition of amino acid to CNR,the CNR film is placed in high pressure and temperature for heat treatment.Transmission electron microscopy(TEM)is used to observe the changes in morphology of CNR with amino acid before and after heat treatment.It is found that heat treatment triggers the formation of non-covalent interactions between amino aggregates and molecular chains.Though XPS and EPR to the changes in structure of amino acids before and after heat treatment is explored.DMA results demonstrate the interfacial interaction between amino acids and NR molecular chains after heat treatment,As the heating time prolongs,much more of the molecular chains react with amino aggregates,leading to the increase of the interface layer,Moreover,the formation of interfacial interactions obviously increases the mechanical properties of CNR with amino acids.(3)Construction of amino acid sacrificial network based on interfacial interactions and its influence mechanism on mechanical propertiesThough different rate stretching and energy dissipation of CNR with amino,the formation mechanism of a sacrificial network through hydrogen between amino aggregates is illustrated.LSCM is used to observe the changes of amino sacrificial network in structure.it is found that the amino aggregate network driven by interfacial interactions as a sacrificial network preferentially ruptures to dissipate large energy for the improvement of fracture toughness.This article studies the interfacial interaction mechanism between free NRC and NR molecular chains,and further elucidates the natural sacrificial network construction mechanism and its effect on the performance of NR through interfacial interaction.The research results of this article can not only help us further understand the reasons for the excellent properties of NR,but also pro_vide important theoretical and experimental basis for the processing of localized high-performance NR.