| Natural rubber is an indispensable polymer material in human social life.It has been widely used in various fields for its good wear resistance、plasticity、acid and alkali resistance、fatigue resistance and other properties,also plays an extremely important role in it.However,the physical properties of natural rubber cannot meet the needs of practical application.Therefore,it is necessary to add a variety of reinforcing fillers in the rubber formula to further improve the comprehensive properties of composite materials and the performance properties of finished products.The addition of short fiber to rubber material can not only retain the high elasticity of natural rubber,but also play the reinforcing performance of short fiber.Also,the orientation of short fiber in rubber matrix can give fully play to its anisotropy,which is conducive to the improvement of finished product performance.Basalt fiber（BF）is a widely distributed,green and environmentally friendly natural fiber,with high temperature resistance、chemical resistance、durability、no pollution、natural degradation and other excellent performance.The combination of basalt fiber and rubber can give composite materials high hardness、high temperature resistance and other comprehensive properties,which has become one of the hot topics in scientific research.However,basalt fiber is difficult to mix,combine and form with rubber matrix due to its characteristics of easy aggregation、large modulus、 smooth surface and high chemical inertness.Therefore,in view of the above problems,this paper mainly explores the modification mechanism and reinforcement mechanism of basalt fiber,as well as the pretreatment method,to prepare basalt fiber/natural rubber composite（BF/NR composite）;The effects of basalt fiber length、the number of additives、the number of modifiers and different processing techniques on the comprehensive properties of BF/NR composites were investigated.The specific work are as follows:1.The modification and reinforcing mechanism of basalt fiber reinforced natural rubber composite were studied.According to the characteristics of basalt fiber,the mechanism of modification of basalt fiber by Si69 and potassium oleate was studied,and the influencing factors and chemical reaction mode in the modification process were analyzed.On this basis,the mechanism of basalt fiber reinforcing natural rubber was studied,and the theory of basalt reinforcing natural rubber composite was established,which provided a theoretical basis for the study of this paper.2.For the problems of smooth surface,low surface energy and high chemical inertia of basalt fiber,the basalt fiber was pretreated by glacial acetic acid solution on the basis of acetone treatment,and the pretreated BF/NR composite was prepared.Scanning electron microscopy（SEM）images show that the surface of basalt fiber after glacial acetic acid treatment is etched into grooves,the surface roughness increases,and the binding sites with rubber matrix increase.The curing performance test showed that the curing time and Mooney viscosity of the composites increased,indicating that glacial acetic acid pretreatment of basalt fiber can reduce the fluidity of the compound and increase the crosslinking density;The mechanical properties of the composites show that the tensile strength and tear strength of the composites are increased by15.3%,18.1% and 7.8% respectively;Dynamic mechanical tests show that the Payne effect is weakened and the wet slip resistance is improved.3.The effects of basalt fiber length and number of components on the comprehensive properties of BF/NR composites were studied.Different variables were set through parameter comparison experiment（fiber length: 3mm,6mm,9mm;add attachments;0、3、5、7、10）BF/NR composites were prepared.The experimental results show that the mechanical properties of the composites increase first and then decrease with the increase of the fiber number,and the optimal value is obtained when the fiber length is 3mm and the fiber number is 5.The tensile strength is increased by 18.4%,the tear strength is increased by 10.3%,the abrasion quantity is decreased by 6.2%,and the elongation at break is increased compared with other parameters.The results show that the Payne effect weakens,the glass transition temperature shifts to the right,and the loss factor decreases.The thermal stability test showed that the weight loss rate of 3mm,5 parts basalt fiber slowed down and the thermal stability was improved.4.The modification method of basalt fiber was explored,and the influence of the number of Si69 and potassium oleate on the properties of the composite was analyzed.The experimental results show that the modification effect of Si69 and potassium oleate is the best when the number of Si69 and potassium oleate is 7.Energy dispersive spectroscopy（EDS）and scanning electron microscopy（SEM）also showed that Si69 and potassium oleate could coat the fiber surface evenly and compactively at7 parts,which improved the interfacial bonding strength.The mechanical properties test showed that the composites with 7 Si69 and potassium oleate had the best properties,the tensile strength increased by 11.7% and 15.6%,the tear strength increased by 10.5% and 12.1%,and the abrasion quantity decreased by 14.1% and14.7%,respectively.5.The effects of different processing techniques on the properties of BF/NR composites were studied.The composite material is prepared by the processing technology of "internal mixing + open mixing" and "intensive mixing + extrusion" to studied the effects of different processing technology and fiber orientation on the mechanical properties and dynamic mechanical properties of BF/NR composites.The experimental results show that the fiber orientation in the rubber matrix is consistent and the radial orientation is higher in the composites prepared by " internal mixing +extrusion".The peak value of the loss factor decreases,and the loss factor decreases the most at 60°C compared with that of the " internal mixing + open mixing" process:the maximum decrease is 15.3% when Si69 is added,and 17.1% when potassium oleate is added,indicating that the "internal mixing + extrusion" process can reduce the rolling resistance of the composite.In conclusion,the basalt fiber added to the rubber material after pretreatment and modification,and oriented in the rubber matrix,can not only improve the binding strength of the fiber and the rubber matrix,but also improve the mechanical properties of the composite material,reduce the rolling resistance,also has a great application prospects,and provides a certain reference value for the production practice. |
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