Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid).

Xingxun Liu,Mingshu Yang,Laurence C Chow,Tongxin Wang,James W Mitchell

doi:10.1155/2014/827028

Abstract

Addition of filler to polylactic acid (PLA) may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA) on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline) have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC), scanning electron microscope (SEM), instron tensile tester, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA.

Highlights

Polylactic acid (PLA)/hydroxyapatite (HA) composites have attracted great attentions for application in tissue engineering recently, because polylactic acid (PLA) and HA are both bioresorbable materials and do not need to be removed by surgery after the bone heals [1]
It is shown that the melting mixing made the inorganic filler distribute homogeneously in PLA matrix, which was confirmed by thermogravimetric analysis (TGA) and scanning electron microscope (SEM)
gel permeation chromatography (GPC) analysis indicated that the melting mixing could decrease the molecular weight of PLA, probably due to the shear, decreasing the mechanical strength

Summary

Introduction

Polylactic acid (PLA)/hydroxyapatite (HA) composites have attracted great attentions for application in tissue engineering recently, because PLA and HA are both bioresorbable materials and do not need to be removed by surgery after the bone heals [1]. Zhou et al [2] have reviewed the different fabrication methods to the preparation of PLA/HA composites such as solvent casting, phase separation, electrospinning, surface coating, melt compounding, and so forth. In order to be used for bone fixation, the tensile strength of PLA/CaP composites in the range of 50–150 MPa is desirable [5,6,7]. While the tensile strengths from most of the reported results are close to the low limit of the cortical bone [5], it is necessary to further improve the tensile strength, for example, up to 100 MPa, so that the tensile strength of the composite can best match those of natural bones from varied locations [5,6,7]

Methods

Findings

Discussion

Conclusion