用IR,~1H-NMR和超离心沉降法表征SBS

CHARACTERIZATION OF SBS TRIBLOCK COPOLYMERS

将IR法和1H-NMR法相结合,可以测定SBS中1,4-PB和1,2-PB的相对含量。本法不必测定溶液的准确浓度和液体池厚度,具有简便、快速的特点。在35℃、SBS浓度为3.0mg/mL环己烷、转速为56100,/min的条件下,用超离心沉降法测得线形SBS的沉降系数(S)随聚苯乙烯含量(WPS)的增加而增加。当WPS<50％(质量)时,S^(-1)=0.97-0.010 WPS;当WPS>50％时,1nS～1nWPS呈直线关系。国产SBS中不含两嵌段共聚物,1,2-PB含量比国外产品约高6％。

Ten samples of SBS triblock copolymers produced by domestic and overseas producers were characterized by UV, IR,1H-NMR, GPC and ultracentrifugation sedimentation methods. A method by using IR and 1H-NMR in combination was suggested for determining the relative contents of trans-1,4, cis-1,4 and 1,2-units in polybutadiene. The method was simple and guick and without the measurement of accurate solution concentration and the thickness of liquid cell. The sedimentation coefficient (S) of linear SBS determined by ultracentrifugation of SBS solution in cyclohexane, with concentration 3.0 mg, at 35°C and 56 100 r/min, increased with the increase of polystyrene content( WPS). When Wps< 50% ( mass), S-1 =0.9-0.010 Wps; when Wps >%, lnS-lnWps was a linear relationship.