Effect of the Molecular Structure of the Polymer and Nucleation on the Optical Properties of Polypropylene Homo- and Copolymers

Abstract

Two soluble nucleating agents were used to modify the optical properties of nine PP homo-and random copolymers. The ethylene content of the polymers changed between 0 and 5.3 wt%.Chain regularity was characterized by the stepwise isothermal segregation technique (SIST), while optical properties by the measurement of the haze of injection molded samples.Crystallization and melting characteristics were determined by differential scanning calorimetry (DSC). The analysis of the results proved that lamella thickness and change in crystallinity influence haze only slightly. A model was introduced which describes quantitatively the dependence of nucleation efficiency and haze on the concentration of the nucleating agent. The model assumes that the same factors influence the peak temperature of crystallization and optical properties. The analysis of the results proved that the assumption is valid under the same crystallization conditions. The parameters of the model depend on the molecular architecture of the polymer. Chain regularity determines supermolecular structure and thus the dependence of optical properties on nucleation.

Determination of Nucleus Density in Semicrystalline Polymers from Nonisothermal Crystallization Curves

“…The effect of nucleus density has been correlated to the optical properties thus we can check the between H and Tcp as well 42,43 , which correlation is used frequently by the industrial practice.…”

Nucleation and impact modification of polypropylene laser sintered parts

“…In In an extensive review, Gahleitner et al [6] established that addition of a nucleating agent generally increases the Young's modulus of a material, and often also its impact resistance. Notable as well is the clarification effect of some nucleating agents, which is attributed to the reduction of crystallite size and respective light scattering reduction [7,8]. Introducing nucleating agents in the SLS process at first glance seems counter-productive, since a side effect of the nucleating agent is an elevation of the crystallization temperature, and corresponding narrowing of the sintering window.…”

Effects of Cyanuric Acid on Crystallization Behavior, Polymorphism, and Phase Transition of Poly(butylene adipate)

“…Also, the mechanical properties like flexural modulus, strength, heat distortion temperature and hardness increase, and the clarity and transmittance improve for the PP. 35,36 Cyanuric acid (CA), a chlorine stabilizer in swimming pools, can form a weak bond with free chlorine in the pool water and protect it from the sun's ultraviolet rays to reduce chlorine loss. Properly managed, CA has been shown to reduce the amount of chlorine needed to maintain the minimum chlorine residual in an outdoor pool.…”

“…Due to the fast crystallization, a part of the PBA completes its crystallization before lowering to the given T c (in particular at the T c which is lower than 25 o C) in the isothermal crystallization process, even if a rapid cooling rate of 100 o C/min is available. Furthermore, the nucleating effect of the CA would highly enhance the crystallization rate of the PBA, so two relatively high T c s (that is,35 and 45 o C) are chosen to investigate the isothermal crystallization process of the PBA component in the PBA/CA. The isothermal crystallization DSC curves of the neat PBA and its composites at 35 and 45 o C are presented in Figures.…”