Physical Properties of Biodegradable Poly(L-lactide) Induced by N, N -Bis(Benzoyl) 1, 3-Cyclohexanedicarboxylic Acid Dihydrazide as Crystallinity Additive

Li-Sha Zhao,Jun Qiao,Yan-Hua Cai,Ting Deng

doi:10.37358/mp.21.2.5477

Abstract

This work is aimed at synthesizing an organic compound N, N -bis(benzoyl) 1,3-cyclohexane-dicarboxylic acid dihydrazide (CABH) to focus on its effect on the non-isothermal crystallization of poly(L-lactide) (PLLA), meanwhile the melting behavior, thermal decomposition process and optical property of PLLA/CABH samples in different CABH concentrations were also investigated. It was found that CABH acted as efficient heterogeneous nucleating agent for inducing PLLA�s crystallization through comparative analysis of melt-crystallization process of the virgin PLLA with PLLA/CABH samples, and a high amount of CABH played a much more significant role in promoting PLLA�s crystallization. Additionally, the melt-crystallization processes also showed that both the cooling rate and the final melting temperature affected the crystallization behavior of PLLA, an increase of cooling rate could weaken the crystallization ability of PLLA/CABH samples, and the final melting temperature of 180�C made PLLA/CABH exhibit the best crystallization ability. For the cold-crystallization process, the cold-crystallization peak became flatter and shifted toward the lower temperature with increasing of CABH concentration, but an increase of heating rate could prevent the cold-crystallization peak from moving to low temperature because of the thermal inertia. The melting behaviors of PLLA/CABH depended on the previous crystallization and heating rate in heating, and the difference in melting behavior of PLLA/CABH samples effectively reflected the nucleation role of CABH, as well as the double melting peaks behavior of PLLA/CABH was thought to due to the melting-recrystallization. The introduction of CABH led to a drop in light transmittance, moreover, this negative effect were more obvious with an increase of CABH loading. In contrast, the fluidity of PLLA was significantly enhanced due to the existence of CABH.

Highlights

The large-scale usage of the non-degradable polymeric products has led to a serious solid waste pollution, and this deterioration is getting worse in the world
The special stereocomplex networks and polyethylene glycol were introduced into PLLA to overcome its poor viscoelastic behavior, low melt strength and insufficient gas barrier properties, as well as the brittleness, the relevant results showed that, in comparison to the virgin PLLA, the elongation at break of the modified PLLA with good light transmittance increased more than 18 times, the O2 permeability coefficient decreased by 61%, meantime, exhibiting the great potential in disposable packaging and agricultural films [15]
The current work is the first to synthesis an organic compound N, N'-bis(benzoyl) 1,3-cyclohexanedicarboxylic acid dihydrazide as a crystallinity additive to evaluate its influence on the non-isothermal crystallization behavior of PLLA in detailed, and the melting behavior, thermal decomposition in air and optical property of CABH-nucleated PLLA were further investigated by differential scanning calorimeter (DSC), transmittance instrument and melt index meter

Summary

Introduction

The large-scale usage of the non-degradable polymeric products has led to a serious solid waste pollution, and this deterioration is getting worse in the world. Poly(L-lactide) (PLLA), made from renewable resources [1], has been globally considered as the most promising bio-based and degradable linear aliphatic thermoplastic polyester due to its excellent biocompatibility, safety, biodegradability [2] and mechanical properties [3], easy processing [4], and green environmental protection during the manufacture [4], etc These advantages have endowed PLLA with tremendous market potential in packaging fields [5,6,7], biomedical fields [8,9,10,11], agricultural fields [12,13,14], and so on. This work is meaningful to rich the category and increase the number of organic nucleating agents, it is helpful to further explore the structure-activity relationship and nucleation mechanism

Objectives

Methods

Results