Preparation And Properties Of Natural Rubber/Polyester Fiber Interfacial Adhesive

With the development of the rubber technology,people put forward new requirements for the rubber products.In order to improve the properties of rubber products and enhance the interfacial adhesio n strength between natural rubber and fibers,polyester fibers were used as the skeleton in this paper.In this paper,the natural rubber/polyester fiber composites were prepared by adding rosin resin and dopamine to natural rubber,respectively.Rosin is a kind of natural resin,which is extracted from the secretion of pine.It is a renewable resource.Rosin resin has the characteristics of high viscosity.As a green material,dopamine has no harm to human and environment,and it has similar catechol structure with viscous protein secreted by marine mussels.In this paper,the mechanical properties and dynamic properties of the natural rubber with tackifier were studied by using MDR,RPA,the universal tension machine and the material testing machine.The interfacial adhesion strength of the composites were studied by the peeling strength test,H pull out force test and De Mattia fatigue test.The rubber/fiber composites with 3phr rosin resin were treated by thermal aging.After aged,the interfacial adhesion strength of the composites and the failure modes were studied by SMZ,SEM and XPS.(1)The adhesion strength of the composites were obviously improved by adding rosin resin into the natural rubber compound.The interfacial adhesion strength between rubber and fiber reached the optimum value when 3phr rosin resin was added to 100 phr natural rubber.Because too much resin was added to the rubber,the crosslinking density was too high and the mobility of rubber molecules was limited,so the adhesion strength decreased.The mechanism of increasing the adhesion strength of the composites by adding rosin resin to natural rubber was as follows: the hydrogen bonds which were formed between hydroxyl groups in rosin resin structure and hydroxyl groups in polyester fibers,and the co-vulcanization of rosin resin and natural rubber during vulcanization which would improve the adhesion effect.(2)The results showed that the interfacial adhesion strength of rubber/fiber composites increased firstly and then decreased with the increase of dopamine contents.When 0.5phr dopamine was added into rubber,the adhesion strength of the composites reached the optimum value.This was due to the formation of hydrogen bonds between the hydroxyl groups on polyester fibers and the hydroxyl or amino groups in dopamine structures.Moreover,dopamine is a small molecule,which can reduce the viscosity of natural rubber and make it easier for rubber molecule to penetrate into polyester fibers.So the adhesion strength of the composite was improved.In the process of dynamic fatigue,the generated heat would cause the thermal aging of composites.Therefore,the dynamic pull-out force of the composites decreased more obviously than the static pull-out force.However,compared with the composite without dopamine,the static and dynamic pull-out force values were significantly improved.The SMZ showed that the remained rubber on the surface of the fibers under static pull-out was more than that under dynamic pull-out,and the rubber left was more uniform.(3)The aging experiment results showed that at the same aging time,the H pull-out force decreased with the increase of aging temperature.At lower temperatures,the most of the failure of rubber/fiber composites occurred at the interface.At moderate temperatures,the failure of rubber/fiber composites occurred at both the interface of the composites and the rubber matrix.At higher temperatures,the failure of rubber/fiber composites occurred mainly at the rubber matrix.The SEM results showed that after aged at high temperature,the rubber matrix of the composite became soft and sticky.The rubber matrix would failure even if a small force was applied.So more rubber remained on the surface of the cords.The surface morphology of the aged composites beca me rough.The higher the aging temperature was,the rougher the rubber surface was.The XPS results showed that the C-C bond on the rubber surface was broken to form the carbon free radicals,and then combined with oxygen in hot air to form the oxygen-containing groups.