Meaning
Exclusion of impurities or low molecular weight species from the growing crystal front occurs during the cooling of a semi-crystalline polymer. This spherulite crystallization rejection concentrates non-crystallizable components into the amorphous regions between the spherical crystal structures. It affects the optical, mechanical, thermal and barrier properties of the molded part by creating microscopic zones of different composition.
Engineers monitor the purity of the resin to minimize the impact of these localized concentrations on the final product performance.
Boundary Accumulation
Trapped material at the edges of the crystals can create weak points in the polymer matrix. When spherulite crystallization rejection is high, the concentration of additives or contaminants in the inter-spherulitic space can lead to stress cracking or reduced impact resistance. This phenomenon is particularly noticeable in polymers with large crystal sizes.
Growth Rate
Speed at which the crystals expand influences the efficiency of the separation process. Rapid cooling limits the time available for spherulite crystallization rejection, leading to a more uniform distribution of species within the solid. Slower cooling allows for more complete exclusion, which can change the way the material responds to environmental stress.
Molecular Distribution
Analysis of the cross section reveals how the different components have been rearranged during solidification. Managing spherulite crystallization rejection is necessary for maintaining consistent performance in parts that are subjected to chemical exposure or mechanical loads. The resulting heterogeneity can influence the rate of diffusion for gases and liquids through the material.
