Tran Thi Thuy

Investigation of cure and mechanical properties of deproteined natural rubber-g-poly(methyl methacrylate)

Investigation of cure and mechanical properties of graft copolymer of deproteinized natural rubber (DPNR) with methyl methacrylate (MMA) prepared by graft copolymerization in latex was presented in this work. It is determined that the increase in scorch time, cure time, hardness and tear strength of the graft copolymer were depended on monomer concentration. With the monomer concentration of 15 g/100 g rubber, the increase of hardness and tear strength are 68 % and 66 %, respectively, compared to DPNR. Besides, there are increasing trends of tensile strength and elongation at break. The optimum concentration of MMA monomer is found at 15 g/100 g-rubber. At this monomer concentration, the hardness and tear strength of the graft copolymer increased, whereas the elongation at break and the tensile strength decreased a bit compared to the natural rubber. Keywords. Natural rubber, polymethyl methacrylate, grafted copolymer, curing properties, mechanical properties.

Crystallization technology: selective polymorphism of L-glutamic acid in anti-solvent crystallization

The selective polymorphism of L-glutamic acid was firstly investigated in anti-solvent crystallization with a high productivity. When the ratio of feed solution and anti-solvent was varied from 90:10 to 80:20, the pure metastable α-form crystal was crystallized at 30 0 C, 18.5g/l feed concentration and 360rpm of agitation speed. However, when the ratio of feed solution and anti-solvent was varied from 70:30 to 40:60, the mixture of α-form and b-form crystal product was precipitated. Further decreasing the ratio of feed solution and anti-solvent from 30:70 to 10:90, the only pure stable b-form crystal was crystallized. The results indicated that the supersaturation determined by the ratio of feed solution and anti-solvent was a key factor to impact on the nucleation process, in which the nucleation of α-form and b-form was favorably crystallized at a low and high supersaturation, respectively, which resulted in the selective polymorphism of L-glutamic acid in the anti-solvent crystallization. Keywords. Crystallization, polymorphism, phase transformation, anti-solvent crystallization.