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 1318C and 46 J g À1 . The achieved crystallization temperature and enthalpy were over 108C and over 10 J g À1 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.

Benzoylhydrazide compounds were evaluated as a nucleating agent for poly(L-lactic acid) (PLA). From the results of the differential scanning calorimetry, octamethylenedicarboxylic dibenzoylhydrazide (OMBH) was found to be most effective for acceleration of PLA crystallization under higher cooling rate of À508C min À1. PLA with OMBH of 1 wt % exhibited very short crystallization half-time with wide range of isothermal temperature from 90 to 1308C. The molding cycle time of PLA with OMBH in injection molding was less than 3 min, and the cooling time was one-third of ethylenebis(12-hydroxystearylamide)/talc system as a nucleating agent. Physical and mechanical properties improved extremely, and the heat distortion temperature of 1248C, flexural modulus of 4.1 GPa, and Izod impact strength of 7.9 kJ m À2 were achieved. This indicates that the utilization of OMBH makes it possible to extend the application range of PLA as automotive parts and electric appliances, which require higher heat resistance and stiffness.

ABSTRACT:The aluminum aryloxide was prepared via the reaction of phenolic antioxidant, 3-(3,5-di-t-butyl-4-hydroxyphenyl)-N-octadecylpropionamide, with triethyl aluminum. Propylene polymerization using supported ZieglerNatta catalyst systems was carried out in the presence of the antioxidant or its aluminum aryloxide. Although the antioxidant gave rise to decrease in catalyst yield and change in hydrogen response, the aluminum aryloxide had no influence on the catalytic polymerization behavior, and thus the obtained polymer characteristics such as molecular weight, polydispersity, and meso pentad as a stereoregularity were comparable to that polymerized without the antioxidant and the aluminum aryloxide. Polypropylene obtained in the presence of the aluminum aryloxide was well stabilized for oxidation and its stability was over 1000 h at 100°C (estimated to be over 30 years at room temperature).

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