Research On Reinforcing Biodegradable Material Poly-DL-Lactic Acid By Equal Channel Angular Extrusion

Biodegradable material research is one of the most focused issues in the field ofbiomedical engineering currently. As a representative biodegradable material,poly-DL-lactic acid(PDLLA) is focused on and applied to clinic due to excellentperformance. However, the mechanical properties of PDLLA are not enough forclinical application. In order to improve the strength of PDLLA, equal channelangular extrusion(ECAE) was firstly used to reinforce PDLLA and to explore newmeans of reinforcing biodegradable materials. This thesis mainly includes thefollowing contents.1. ECAE device was developed and PDLLA was processed with the device.Bending experiments show that the strength of PDLLA was increased significantlyvia strong plastic deformation with ECAE.2. Reinforcing mechanism and effect of PDLLA with ECAE were analyzed bymeans of scanning electron microscope (SEM), wide angle X-ray diffraction (WAXD)and differential scanning calorimetry (DSC). It can be concluded that ECAE is aneffective means on strengthening, toughening PDLLA and improving thermalstability and microstructure of PDLLA.3. By means of the finite element software Deform-3D for plastic deformation,numerical simulation on ECAE process was carried out by rigid-plastic arithmetic.Principle of plastic deformation in ECAE was analyzed. Meanwhile, the effect offriction on ECAE was investigated. Results of numerical simulation show that thefriction has an important influence on the uniformity of deformation and ECAEforce and has little influence on mean effective strain of ECAE. What's more, it wasverified that deformation can be accumulated to reach large strain value after severaltimes of ECAE.