Vacuum Effect on the Lactide Yield

The vacuum effect on the yield and purity of lactide obtained by catalytic lactic acid oligomer depolymerization was investigated. As raw material for the lactic acid oligomer synthesis the L-lactic acid aqueous solution was used. It was shown that the highest yield of raw-lactide takes place via distillation under a vacuum. The raw-lactide in all fractions was purified by recrystallization from dry ethyl acetate. The highest yield of raw-lactide is observed at a vacuum of 10 ... 15 mbar. The distillation process of raw-lactide is complicated with chemical reactions. Control of the reaction, raw materials and products was performed using DTA, gel permeation chromatography, infrared spectroscopy and high performance liquid chromatography

Effect of annealing on mechanical and morphological properties of Poly(L-lactic acid)/Hydroxyapatite composite as material for 3D printing of bone tissue growth stimulating implants

In this work, effect of additional annealing on mechanical and morphological properties of 3D-printed PLLA/HAp composite scaffolds of three compositions (12.5, 25, and 50 wt.% of HAp) was investigated. Morphology and Young's modulus of 3D-printed scaffolds were investigated by scanning electron microscopy and nanoindentation. It has been shown that additional annealing does not have an effect on the homogeneous distribution of HAp powder in the PLLA-matrix. Results of nanoindentation showed growth of Young's modulus after annealing. The maximum value of 9393 ± 709 MPa Young's modulus was reached for the annealed composite with 50 wt.% of HAp

Influence of Storage Conditions on the Stability of Lactide

The objective following of the present study was to investigate the effect of different storage time and conditions on the stability of lactide. In this study the samples of lactide with different purities were stored under three various storage conditions and the compound integration was monitored for a period of 2 weeks. The storage conditions selected were (1) in the desiccator, (2) in the glove box under argon and (3) under ambient atmosphere. The purity of samples was performed on HPLC and Karl Fischer titration during all period of storage. It was shown that the initial purity of the lactide has a significant bearing on the lactide degradation