Study On Phase Distribution And Properties Of Eucommia Ulmoides Gum/Natural Rubber Blends

Natural rubber(NR)is widely used in various fields of national defense and national economy for its excellent physical and chemical properties.Not any synthetic rubber can replace the role of natural rubber up to now since it was discoveried for hundreds of years.As the world's largest rubber consumption,as well as the largest tire importer,China consumes a lot of NR each year.However,China's NR production is very limited for climate reason,so over 80%NR consumption have to be imported from Southeast Asia every year.In recent years,with the implementation of the EU Reach regulations,the EU label law and a series of environmental laws and regulations for tire industry,as well as the world's major tire manufacture giants,like Continental and Bridgestone,have planned to produce tire with 100%renewable materials.China also needs to develop the domestic second natural rubber resources to ease the plight of NR in China.Eucommia ulmoides(Eu)gum,as the China's unique renewable natural polymer material,can be extracted from the tissues of eucommia ulmoides oliver,which widely cultivated in the central and western regions of China.It is an isomer of NR and its chemical structure is trans-1,4-polyisoprene.Since the cis-trans isomers have a large difference in molecular regularity,Eu gum and NR have big differences on their macro performance.At room temperature,Eu gum is a hard plastic because of its crystalline behaviour,while NR is a very flexible elastomer for its amorphous structure.However,if the crystalline structure of Eu gum could be destroyed by crosslinking,it would be an elastomer too.To a certain extent,if Eu gum could be blended with NR and used as conventional rubber materials,which,on one hand,can alleviate the problem of extreme shortage of NR,on the other hand,can also improve the NR's fatigue resistance,tearing resistance and other aspects of performance.The experiment is divided into four parts.In the first part,the molecular structure,molecular weight and molecular distribution,crystalline morphology and mechanical properties of the Eu gum were characterized and studied in order to understand the basic properties of Eu gum.At the same time,synthetic trans-1,4-polyisoprene(STPI)was also studied for comparison.And then the performances of vulcanized Eu gum were studied by two kinds of vulcanization systems commonly used in traditional rubber field,which mainly focused on the change of crystalline structure,molecular structure and mechanical properties during the three stage of vulcanization,namely slightly crosslinked stage,highly cross-linked stage and elastomer cross-linked stage.It was found that the mechanical properties of Eu gum with sulfur vulcanization system showed obvious tensile enhancement phenomenon after the crystalline structure was completely destroyed.In the second part,as the atomic force microscopy(AFM)can detect the distribution of the two phases with different performances in the microscopic condition.The phase distribution of the unvulcanized Eu gum and NR are studied with AFM.It was found that a small amount of Eu gum was dispersed in the continuous phase of NR.The dispersed particles of Eu gum were very small.At the same time,with the increase of the content of Eu gum,the ridge-like continuous phase was gradually formed under the shearing effect of the open mill.And an irregular transition phase also formed between the two phases of Eu gum and NR.In the third part,the general properties of Eu gum/NR blends were studied,which indicated that Eu gum/NR blends have a good vulcanization performance.At the same time,their mechanical properties are not declined obviously,but the fatigue life,resistance to fatigue lines,toughness and tear resistance are obviously improved.In the fourth part,the properties of the Eu gum/NR blends filled with carbon black were studied.Because of the main application areas of NR is in the tire field,meeting the application properties requirements of tire is the main studying direction of Eu gum/NR blends.Therefore,the rolling resistance,mechanical properties,cutting resistance and compression heat generation of the carbon black reinforced Eu gum/NR blend rubber materials were studied.The results showed that the performances of rolling resistance,cutting resistance,tear resistance and compressive heat generation are improved,while the tensile properties have a slight decrease.