Diffusion-controlled growth of lamellar crystals in an isotactic polystyrene–polyphenylene oxide blend

The growth rates of lamellar crystals grown onto preseeded fibrillar crystals (“shishes”) in isotactic polystyrene and blends of isotactic polystyrene (iPS) with polyphenylene oxide are followed by using transmission electron microscopy. The preseeded fibrillar crystals avoid the problem of timedependent primary nucleation. The time dependence of lamellar growth is investigated. At a concentration of 50% PPO in iPS, the lateral lamellar growth rate of the precipitating isotactic polystyrene crystals conforms to a time law characteristic of diffusion-controlled growth (R ∝ t^1/2). Diffusion coefficients are estimated from the growth kinetics. The method could prove a simple means of measuring diffusion coefficients in polymer blends in which one component is crystallizable.