Molded tube of improved performance

Abstract

A tube, preferably a centrifuge tube, molded of a blend of 25-35 weight percent of polystyrene and 75-65 weight percent of styrene-butadiene rubber block copolymer has improved performance compared to a tube of pure copolymer.

1 . A medical tube comprising sidewalls and a closed end, said sidewalls and closed end comprising a blend of 25-35 weight percent polystyrene, based upon total weight of the polymer, having a melt flow index of 7-11 g/10 min and a styrene-butadiene rubber block copolymer having a melt flow index of 10-12 g/10 min, said tube having diminished leakage or plastic deformation compared to identical, in size and shape, tubes of pure styrene-butadiene copolymer.  
     
     
         2 . The tube of  claim 1 , which is a round bottom tube.  
     
     
         3 . The tube of  claim 1 , which is a centrifuge tube.  
     
     
         4 . The tube of  claim 1 , which is sterilized with gamma radiation.  
     
     
         5 . The tube of  claim 4 , wherein said radiation has a maximum dose of 23 Kgy.  
     
     
         6 . A The centrifuge tube of  claim 12 , comprising a blend of 28-32 weight percent of polystyrene having a melt flow index of 7-11 g/10 min and 72-68 weight percent of styrene-butadiene rubber block copolymer having a melt flow index of 10-12 g/min.  
     
     
         7 . The centrifuge tube of  claim 12 , comprising a blend of 29.5-30.5 weight percent of polystyrene having a melt flow index of 7-11 g/10 min and 70.5-69.5 weight percent of styrene-butadiene rubber block copolymer having a melt flow index of 10-12 g/10 min.  
     
     
         8 . An assembly comprising the tube of  claim 1 , and a hermetically sealed closure therefor.  
     
     
         9 . The tube of  claim 1 , wherein said blend comprises 28-32 weight percent, based upon total weight of the polymer, of polystyrene having a melt flow index of 7-11 g/10 min and 72-68 weight percent of styrene-butadiene rubber block copolymer.  
     
     
         10 . The tube of  claim 1 , wherein said blend comprises 29.5-30.5 weight percent, based upon total weight of the polymer, of polystyrene having a melt flow index of 7-11 g/10 min and 70.5-69.5 weight percent of styrene-butadiene rubber block copolymer.  
     
     
         11 . The tube of  claim 1 , wherein said blend comprises 25-35 weight percent, based upon total weight of the polymer, of polystyrene having a melt flow index of 7-11 g/10 min and 75-65 weight percent of styrene-butadiene rubber block copolymer.  
     
     
         12 . The tube of  claim 11 , wherein an innermost surface of the tube comprises said block copolymer.  
     
     
         13 . The tube of  claim 11 , wherein said sidewalls comprising said block copolymer extend as a single layer from an innermost surface of the tube to an outermost surface of the tube.  
     
     
         14 . A centrifugal tube comprising sidewalls and a closed end, said sidewalls and closed end comprising a blend of 25-35 weight percent polystyrene, based upon total weight of the polymer, having a melt flow index of 7-11 g/10 min and 75-65 weight percent styrene-butadiene rubber block copolymer having a melt flow index of 10-12 g/10 min, said tube having diminished leakage or plastic deformation compared to identical, in size and shape, tubes of pure styrene-butadiene copolymer.  
     
     
         15 . The tube of  claim 14 , wherein an innermost surface of the tube comprises said block copolymer.  
     
     
         16 . The tube of  claim 14 , wherein said sidewalls comprising said block copolymer extend as a single layer from an innermost surface of the tube to an outermost surface of the tube.  
     
     
         17 . The tube of  claim 1 , wherein an innermost surface of the tube comprises said block copolymer.  
     
     
         18 . The tube of  claim 1 , wherein said sidewalls comprising said block copolymer extend as a single layer from an innermost surface of the tube to an outermost surface of the tube.