Preparation And Properties Of Functional Eucommia Ulmoides Gum Composites

The development of smart materials is one of important directions of modern high-tech new materials.In particular,the research on shape memory polymers(SMPs)with responsive functions and self-healing polymers(SHPs)with self-healing functions has attracted much attention.SMPs can respond to stimuli(such as heat,light,electricity,magnetism,and solvents,etc.),and change their shapes through designed programming steps,which is usually reversible.SHPs can self-repair their damaged parts through self-sensing and restore the original performance,which have advantages of durability,long service life and low cost.These two kinds of smart materials have considerable application prospects in daily life,aerospace,military transportation,biomedical and other industrial products.Synthetic Eucommia ulmoides gum,which is trans-1,4-polyisoprene(TPI)and a semi crystalline polymer containing double bonds,has the inherent structural advantages as shape memory and self-healing materials.Therefore,the development of TPI based functional materials with shape memory and self-healing properties has important theoretical research value and practical application significance.In this paper,trans-1,4-polyisoprene(TPI)was used as matrix to prepare functional composites with both shape memory and self-healing properties.The relationship between its microstructure and mechanical properties,thermal properties,shape memory properties,self-healing properties and other properties was studied in this manuscript.The detailed research content is as follows:Firstly,the thermoplastic small molecule PEW was introduced into the TPI rubber matrix to prepare TPI/polyethylene wax(PEW)composites.PEW has good high temperature fluidity and can also increase the content of crystalline microdomains in the system.Therefore,the effects of blending ratio and vulcanization system in the system on the comprehensive properties of composites were explored.In the sulfur(S)vulcanization system,the tensile strength of the composites decreased continuously with the decrease of the TPI/PEW blending ratio.In terms of shape memory properties,the shape fixation ratio(R_f)and shape recovery ratio(R_r)showed increasing and decreasing trends,respectively.When the TPI/PEW was 50/50,the healing efficiency of the composites reached the highest value of 20.74%.In the peroxide DCP vulcanization system,with the increase of the TPI/PEW blend ratio,the tensile strength and crystallinity of the composite material both increased.In particular,when the TPI/PEW was 50/50,R_f,R_r and the healing efficiency reached 94.28%,93.80%and 31.25%,respectively.Secondly,the ionic cluster crosslinks,high-modulus amorphous regions and ethylene crystalline microdomains contained in Surlyn resin provide a good premise for the functional modification of TPI.Therefore,TPI/Surlyn composites were prepared by introducing Surlyn into TPI matrix.The effects of blending ratio and peroxide DCP content on the comprehensive properties of TPI/Surlyn composites were mainly explored.With the decrease of the TPI/Surlyn blending ratio,the mechanical properties of the composites basically showed a trend of enhancement,and R_f,R_r continued to rise due to the introduction of sarin.In addition,when the blending ratio was 30/70,the healing efficiency was as high as 87.41%.After that,the influence of DCP dosage was explored.With the increase of DCP fraction,the tensile strength of the composite showed an increasing trend,R_f increased due to the increase of covalent cross-linking,while R_r reached the maximum value of 96.88%when the dosage of DCP was 1.0 phr.When the amount of DCP did not exceed 1.0 phr,the composites could achieve surface healing.Finally,functionalized TPI/HXNBR composites were prepared by using the reaction of hydrogenated carboxylated nitrile butadiene rubber(HXNBR)with zinc peroxide(Zn O₂)to build an ionically cross-linked network in the system.The effects of blending ratio and zinc peroxide(Zn O₂)content on various properties of TPI/HXNBR composites were explored.With the increase of TPI/HXNBR blending ratio,the covalent crosslink network density of the system increased,the content of ionic crosslinks decreased,and the crystallinity decreases,then the mechanical properties of the composite material were further enhanced,R_f gradually decreased,and R_rincreased,and healing efficiency was also declining.The research on the Zn O₂particles content showed that the cross-linking density first rised and then decreased with the increasing of Zn O₂ content,which was similar to mechanical properties,and R_fincreased and R_rdecreased in shape memory behavior.The self-healing properties of the composites reached 23.62%when Zn O₂ content was 20 phr.