Abstract: A method of preparing polylactic acid (PLA) microsphere and polylactic-co-glycolic acid (PLGA) microsphere is provided, including the following steps. A first solution is provided, including polylactic acid or polylactic-co-glycolic acid and an organic solvent. A second solution is provided, including polyvinyl alcohol, sodium carboxymethyl cellulose and an aqueous solution. The first solution is added to the second solution and, at the same time, the second solution is agitated until polylactic acid is solidified to form a plurality of polylactic acid microspheres, or until polylactic-co-glycolic acid is solidified to form a plurality of polylactic-co-glycolic acid microspheres. The polylactic acid microspheres or polylactic-co-glycolic acid microspheres are collected.

Abstract: Semi-aromatic copolyamides and copolyester-amides are obtained by placing an aliphatic polyamide into contact with an aromatic hydroxyacid or aminoacid, by operating at high temperature, under melting conditions, possibly in the presence of a catalyst, with a ratio of the monomer units of aliphatic polyamide to the mols of aromatic hydroxyacid or aminoacid comprised within the range of from 20:1 to 1:1.The semiaromatic copolyamides and copolyester-amides so obtained can display a thermotropic liquid-crystal behavior as a function of their content of aromatic units linked inside the molecular chain. Their elastic modulus results to be improved relatively to the alifatic polyamides used as the starting product, and the elongation at break results to be decreased.Such semiaromatic polyamides and copolyester-amides can find application in the production of high-stiffness articles, by means of moulding or extrusion processes.

Abstract: Semi-aromatic copolyamides and copolyester-amides are obtained by placing an aliphatic polyamide into contact with an aromatic hydroxyacid or aminoacid, by operating at high temperature, under melting conditions, possibly in the presence of a catalyst, with a ratio of the monomer units of aliphatic polyamide to the mols of aromatic hydroxyacid or aminoacid comprised within the range of from 20:1 to 1:1.The semiaromatic copolyamides and copolyester-amides so obtained can display a thermotropic liquid-crystal behaviour as a function of their content of aromatic units linked inside the molecular chain. Their elastic modulus results to be improved relatively to the alifatic polyamides used as the starting product, and the elongation at break results to be decreased.Such semiaromatic polyamides and copolyester-amides can find application in the production of high-stiffness articles, by means of moulding or extrusion processes.