Preparation And Foaming Investigation Of PLA/PEG Composite

Poly(lactic acid) has the most potential to replace the petrol-based polymers for its highstrength, optical transparency, and biodegradability. In recent years, the application of PLA intissue engineering field has attracted extensively attention in view of its excellentbiocompatibility. However, PLA used as package material was limited due to its brittleness atroom temperature. Also in tissue engineering field, the complicated process and theintroduction of organic solvent during scaffold preparation is urgently to be solved.Firstly in this study, PLA was melt-blended with PEG to enhance its toughness whilemaintaining its biodegradability, and the influence of PEG on the mechanical properties,thermal properties, crystallization properties, and rheological properties were alsoinvestigated to make preparation for the following foaming process. Secondly, a newpreparation technique for tissue engineering scaffold was explored, that is to say, we inducedcell break on the cell wall via matrix viscoelasticity control during the supercritical fluid batchfoaming process, thus an interconnected structure with high porosity was obtained. Finally,PLA/PEG/OMMT composite with both excellent toughness and thermal stability wasprepared, and its foaming behavior was further investigated to verify the feasibility of thebatch process for scaffold material preparation.The results showed that the incorporation of PEG enhanced the mobility of the PLAchains, thus lowered the glass transition temperature and the cold crystallization temperature,and improved the impact toughness and the elongation at break of the PLA matrix. Smallmolecular PEG acted as lubricant to weaken the viscoelasticity of the matrix, which led to thecell break during the cell expansion process, in addition, the interconnectivity of the foamstructure improved with the PEG content.XRD and SEM results showed that PEG enhanced the dispersion of the clay palates inthe PLA matrix, and thus the intercalated structure was formed, which contributed to theenhanced thermal stability. However, the interfacial bonding of OMMT and PLA matrix waslimited, the tensile strength and the flexural strength decreased to some extent with significantly increase of the modulus and the izod impact strength. Furthermore, theincorporation of the OMMT enhanced the viscoelasticity of matrix, and the cell breakphenomena significantly reduced with the increasing OMMT content, which confirmed thatthe foam structure of the matrix can be flexibly altered via matrix viscoelasticity control.