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本文報告測定本所合成研究室用乳液聚合在50°時所製備的丁苯橡膠分子量分佈的結果。我們在1％苯溶液中,加入甲醇作沉澱劑經分級沉澱後,用粘度法測定各級份的分子量。所得分子量分佈曲線,在分子量等於50,000處有一個明顯的高峯,與前人的結果相符合。特性粘數[η]>3的級份,從它們的溶解度和在甲苯溶液中的粘度數據,我們認為有顯著的支鏈和交聯的存在,約佔試樣的25％。甲苯溶液的粘度數據指示在[η]<3時,k′=0.36,與分子量無關,而且k′+β=1/2;當[η]>3時,k′值顯著地增大,而且k′+β>1/2。 這些差異的大小,我們認為可以看作丁苯橡膠分子支鏈或交聯程度的一種量度。 從本實驗所得的丁苯橡膠的分子量分佈曲線,我們建議同時用■和■來做橡膠的品質指示。
This paper reports the results of the determination of the molecular weight distribution of styrene-butadiene rubber prepared by emulsion polymerization at 50 ° in our synthetic laboratory. We in 1% benzene solution, adding methanol as a precipitating agent after precipitation, the viscosimetric method to determine the molecular weight of each fraction. The resulting molecular weight distribution curve, at a molecular weight of 50,000 has a significant peak, consistent with previous results. Intrinsic viscosity [η]> 3 fractions, from their solubility and viscosity data in toluene solution, we consider that there are significant branches and cross-links, accounting for about 25% of the sample. The viscosity data of the toluene solution indicate that k ’= 0.36 at [η] <3, regardless of the molecular weight, and k’ + β = 1/2; k ’values increase significantly when [η]> 3 and k ’+ β> 1/2. The size of these differences, we believe can be seen as a measure of the degree of branching or cross-linking of styrene-butadiene rubber. From the molecular weight distribution curve of styrene-butadiene rubber obtained in this experiment, we suggest using both ■ and ■ for rubber quality indication.