The Study On Different Strains Of Natural Rubber Latex Property

Three different strains of freshly natural rubber latex were selected in the same year,that is the early stage (May and June), the middle stage (August and September) and the late stage (November and December) of the tapped rubber. Reken628chosen from Hainan areas was selected as research objective of three stages, while RRIM600grown locally was regarded as control sample; the strains of Yunyan77-2and Yunyan77-4planted in Yunnan areas were regarded as control sample of RRIM600grown locally;Zhanshi327-13from Guangdong planting areas regarded Zhanshi93-14locally grown as control sample;meanwhile physiological parameter of freshly natural rubber latex, mechanical stability of concentrated natural rubber latex and volatile fatty acids were all analyzed. Physical and mechanical properties of vulcanized rubber films, relative molecular weight and molecular weight distribution of raw rubber, Mooney viscosity, six indicators, physical and mechanical properties of vulcanized rubber were mainly investigated. At the same time, every kind of strains on raw rubber about their processability was analyzed with rubber process analyzer, each strains of raw rubber on their processability was made a research on; then using thermal analyzer to analyze various strains of raw rubber about their thermal gravimetric analysis, and analyzed the degradation rule under nitrogen atmosphere; molecular weight and molecular weight distribution were analyzed with gel permeation chromatograph. By analyzing and changing of different strains of natural rubber latex in three stages about their physiological indicators, quality indicators of raw rubber, vulcanized rubber films of concentrated natural rubber latex, and physical and mechanical properties of concentrated natural rubber latex, a good theoretical basis had been provided for processing, utilization of natural rubber, even for the promotion of different strains.The results showed that:sucrose content of three stages of Yunyan77-2were in a rising trend, contents were all high, and higher than control sample RRIM600(云). The yellow body burst index of middle stage of Reken628was high, while the late stage of it was low, and middle stage and late stage of it were both lower than control sample.Mechanical stability of early stage of Yunyan77-4was high, late stage of it was low, and both stages of it were higher than control sample RRIM600(云), while late stage of it was lower than control sample. For Reken628, VFA of middle stage of it was high, the rest of the two stages of it were the same, and middle stage of it was lower than control sample, late stage was of it was higher than control sample. In the terms of concentrated vulcanized rubber films, for Zhanshi327-13, tensile strength and mechanical properties in the early and late stage was bigger than control sample, while the middle stage was smaller than control sample. With regard to Yunyan77-2, its tensile strength and mechanical properties in the early stage was bigger than control sample, the middle stage had the same value,thelate stage was bigger than control sample.For each kind of strains of raw rubber, their six indicators of three stages basically conformed to the national standard, in the early stage, Mooney viscosity and P0of Zhanshi327-13were bigger than control sample, while were smaller than control sample for PRI. In all the strains of middle stages, Mooney viscosity and P0of Reken628gave the highest value, PRI the lowest, RRIM600(Hainan) was contrary to them. In the late stage, Mooney viscosity and Po of Yunyan77-2and Yunyan77-4were bigger than control sample, PRI was smaller than control sample.As for the physical and mechanical properties of vulcanized rubber films, in the early stage, tensile strength and tear strength of Reken628were bigger than control sample. In the middle stage, the two factors of Yunyan77-2and Yunyan77-4were bigger than control sample. Unlike the first two stages, the two indicators of Reken628were smaller than control sample. The study showed that modulus and elongation increased with the increase of tensile strength and tear strength, but the latter two not necessarily increased with the increase of the former two.TG experiments showed that:every strains of raw rubber on thermal degradation was one-step reaction. In the early stage, To and Tp of Zhanshi327-13were bigger than control sample, heat stability was better than control sample. In the middle and the late stage, To and Tp of Yunyan77-4and Zhanshi327-13were bigger than control sample, heat stability of two were better than control sample; while the heat stability of Yunyan77-2and Yunyan77-4were not better than control sample; the heat stability of Reken628was poorer than control sample.The RPA measurement results showed that:every strain increasing with the frequency, elastic modulus also increased to a gentle value, the loss factor reduced to a certain value. In the early stage, elastic modulus of Zhanshi327-13was bigger than control sample, while the loss factor was smaller than control sample. In all the strains, the highest elastic modulus was Yunyan77-2, while the loss factor lowest, which was contrary to Zhanshi327-13. The GPC measurement results revealed that:In the early stage, relative molecular weight of Zhanshi327-13was bigger than control sample, coefficient of distribution was bigger than control sample, but the two were close each other, so as to the elastic modulus and the loss factor. In the middle stage, relative molecular weight of Reken628was bigger than control sample, coefficient of distribution was smaller than control sample. In the late stage, relative molecular weight of Zhanshi93-114was19.91×104, coefficient of distribution was3.72, which were close to relative molecular weight of RRIM600(Yun), that is19.83×104, also close to the coefficient of distribution, which was3.72, and also were close to their elastic modulus, meanwhile showed some correlation.