The glass transition temperature of star‐shaped polystyrenes

摘要

AbstractThe glass transition temperatures of linear and four‐ and six‐branched regular star polystyrenes are measured by penetration, differential scanning calorimetry, and a density gradient technique. The results of the three methods show that the glass transition temperature depends on the concentration of chain ends in the polymer sample. An attempt is made to assess the influence of the presence of the branch point on the glass transition temperature using a series of four‐branched polystyrenes containing varying amounts of isoprene near the branch point. However, any effect of the central branch point on the glass transition temperature is obscured by plastification of polystyrene by polyiso