Preparation And Properties Of Functional Eucommia Ulmoides Gum Elastomer

In recent years,it has become a new trend to replace non-renewable petroleum-based materials with renewable bio-based materials.As an important biomolecular material,eucommia ulmoides gum(EUG)is widely distributed in most areas of China.Due to its abundant resources and renewable properties,the development and application of EUG is of great significance.However,EUG is easy to crystallize,and it is hard plastic at room temperature,which limits the scope of its application.Thus,how to turn EUG into elastomer by chemical modification and give it more functions is very important to broaden the application field of EUG.In this paper,two chemical modification methods,epoxy ring-opening modification and cyclization modification,were used to prepare eucommia ulmoides ester(EUET)and cyclized eucommia ulmoides gum(CEUG)elastomer,respectively.After modification,EUG has not only been successfully transformed into an elastomer,but also has the properties of self-repairing,oil resistance and damping,which further expanded the application field of EUG.Specifically,this paper mainly includes the following two parts:In the first part,EUG was epoxidized by performic acid formed from hydrogen peroxide and formic acid in situ in toluene solution,and then undergo a ring-opening reaction with aid of acetic acid.It was found that EUET contained both a-hydroxyl-ester and β-hydroxyl-ester in the molecular chain.Unlike EUG,EUET was no longer crystallized due to the reduction of regularity,and it had been successfully converted into elastomer materials.Furthermore,because of the presence of polar groups and the hydrogen bond between them,EUET could achieve self-healing under the condition of 50℃,and its vulcanizate possessed excellent mechanical properties,oil resistance and damping properties.In the second part,the bio-based cyclized eucommia ulmoides gum(CEUG)elastomer with various degree of cyclization was prepared using TiCl4/CH3COOH as catalysts.1H-NMR and FT-IR techniques were used to obtain structure information.It was found that di-,tri-,and tetra-substituted olefins in the cyclized sequence were formed during cyclization.DSC and XRD results indicated that cyclized structure could inhibit crystallization.When the degree of cyclization reached 8.20%,crystallization disappeared and the material transformed from plastic into elastomer.With increasing of the degree of cyclization,the glass transition temperature(Tg)of CEUG increased and the thermal stability enhanced,but the molecular weight decreased significantly.Above all,DMA results showed that the tanδmax could reach 1.22 when the degree of cyclization was 20.01%,and the damping temperature range could be adjusted by controlling the degree of cyclization.