| Natural rubbers(NR)are attractive as a renewable strategic resource widely applied in numerous fields due to the superior mechanical properties.Whereas the inferiority on ozone aging resistance extremely limits the service life of rubber products.Thus,a strong research momentum to study the performance of non-rubber constituents have been motivated in last decades.The main non-rubber constituents,such as the protein and acetone extract,play the role of natural anti-aging agents on the automotive industry in particular.According to the previous studies on the natural rubber properties and non-rubber constituents,there is a causal relationship between the main non-rubber constituents and mechanical properties.To study the effect of non-rubber constituents on NR,and to exclude the impact of single factor in non-rubber components was used as an effectively solution.The traditional design method of orthogonal test design including multi-factor and multi-level and the repetition of experiments,to achieve the accurate result that may greatly impede the research progress.Moreover,rarely researches on NR multi-factor and multi-level have been reported,which may related to the lack of theoretical basics and the labile factors.In this study,the uniform experimental design method is applied,which take the multi-factor and multi-level into account by using fewer experiments.Through the addition of protein and acetone extract combined with uniform experimental design method,the effects of the main non-rubber components and NR ozone aging performance were experimentally arranged and a regression analysis model was established for exploratory research.It was found that an obvious ozone aging layer and non-aging layer were observed after the ozone aging,besides,the physical and mechanical properties of NR still maintained the same level of non-aging layer.Moreover,the added protein and acetone extract exhibits a well compatibility with rubber in the low concentration,however it may do harm to the mechanical performance on NR in the high concentration.Attractively,the added protein leaded to a damage of mechanical properties,while the added acetone extract improved the mechanical properties on NR.The added protein and acetone extract well improve the ozone aging resistance of the rubber,and the effect of the two factors at the same time is significantly better than the single factor.Infrared analysis found that protein and acetone extract show minor influence on each other,and the reaction with ozone more intense than that of rubber molecules delays the attack of NR by ozone,which is beneficial to improve the ozone aging resistance of rubber.By establishing a regression analysis model based on the results of the uniform experimental design method,it is found that the "two factors"(protein and acetone extract)have a positive correlation with the effects of mechanical and ozone aging properties,and there is a significant causal relationship.?"Two factors" regression analysis of mechanical properties obtained the optimal regression equation::y=-2.9361+34.9462*x1+16.6204*x2-15.6706*x1*x2+2.0951*x12-1.9198*x22,According to the equation,achieve the optimal mechanical properties data:the nitrogen content is 0.19%,the acetone extract content is 3.535%,and the tensile strength is 27.89Mpa.?"Two factors" regression analysis of ozone aging performance,and the optimal regression equation:y=-132.425+595.7924*x1+55.44496*x2-26.0793*x1*x2-817.13*x12-5.8934*x22.According to the equation,the optimal ozone-resistant aging conditions were obtained:the nitrogen content was 0.30%,the acetone extract content was 4.04%,which could cause the retention rate of tensile strength after rubber ozone aging is 68.67%?... |
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