Modification and characteristics of biodegradable polymer suitable for selective laser sintering

This paper investigates the methodology to modify biodegradable polymers having random size, shape, and molecular weight into particles appropriate for selective laser sintering (SLS), which is a powerful technique to build arbitrarily complex objects. Polycaprolactone (PCL), which has recently drawn significant attention as biodegradable polymer for potential application in bone and cartilage repair, was used in this study. PCL powders with various sizes, shapes, and molecular weights were modified by chemical processes and resultant shape, size distribution, degree of crystallinity, and thermophysical properties were observed by optical and scanning electron microscopy (OM and SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The modified PCL as well as raw material were sintered by CO₂ laser irradiation with 10.6-ím wavelength, and specimens for tensile testing were fabricated. By simple design of experiment (DOE) method, macro and micro structures of the fabricated parts were observed depending on various processing parameters related with SLS. Finally, micro tensile tests were conducted, and tensile properties as a function of molecular weight and particle shape were obtained. All the procedures attempted in this study can be extensively applied to other biodegradable polymers. Since SLS has an advantage to deposit multiple materials spatially, the obtained mechanical properties can be referred to generate functionally graded material (FGM), which incorporates deliberately designed transition in materials composition and properties within a component, by SLS.