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Nucleation Ability (nucleation + ability)
Selected AbstractsNucleating agent for poly(L -lactic acid),An optimization of chemical structure of hydrazide compound for advanced nucleation abilityJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007N. Kawamoto Abstract A series of compounds having hydrazide groups was prepared and evaluated as nucleating agent for poly(L -lactic acid) by differential scanning calorimetry. Hydrazide compounds derived from benzoic acid, 2-hydroxybenzoic acid, 3- tert -butylbenzoic acid, and 2-aminobenzoic acid, where two of hydrazide compounds connected by four methylene chain were evaluated in series. Benzoylhydrazide type was found to be more effective on the enhancement of crystallization of poly(L -lactic acid). Effects of connecting length of methylene chain numbers between two of benzoylhydrazide on the nucleation ability were also evaluated. Benzoylhydrazide-type compound having 10 methylenes, that is, decamethylenedicarboxylic dibenzoylhydrazide demonstrated excellent nucleation ability, and the resulted crystallization temperature and enthalpy of PLA with the compound of 1 wt % loading were 131°C and 46 J g,1. The achieved crystallization temperature and enthalpy were over 10°C and over 10 J g,1 higher than PLA with conventional nucleating agents, such as talc and ethylenebis (12-hydroxystearylamide). Thus, the improvement in processability, productivity, and heat resistance of PLA is suggested to be achieved by using decamethylenedicarboxylic dibenzoylhydrazide as a nucleating agent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 198,203, 2007 [source] Advanced nucleating agents for polypropylene,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2007Dima Libster Abstract The present short review aims to summarize advanced nucleating agents for polypropylene (PP). Reviewing the relevant literature, we focused on powerful nucleators that are capable of significantly increasing the crystallization temperature of the polymer at very low working concentrations and also serving as clarifying agents. The nucleation mechanism and efficiency of these compounds are discussed in detail. The nucleating agents were divided into groups according to their tendency to induce monoclinic (,), hexagonal (,), or orthorhombic (,) PP cell geometries. The major , -nucleators and clarifiers are sorbitol-based compounds that speed-up the polymer crystallization due to gelation phenomena and induction of epitaxial crystallization by the metal salts of substituted aromatic heterocyclic phosphate. Among , -nucleators, N,N,-dicyclohexyl-2,6-naphthalene dicarboxamide was found to be very efficient and its nucleation ability was highly concentration dependent. In addition, it was shown that nucleation efficiency of a nucleator can be significantly increased by a new dispersion method comprising its solubilization in a microemulsion. Moreover, the nucleator (HPN-68) increased the , -modification present in the polymer. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||