Porous alumina ceramic via gelcasting based on2-hydroxyethyl methacrylate dissolved in tert-butyl alcohol

To obtain porous alumina ceramic with high strength,a novel gelcasting system based on 2-hydroxyethyl methacrylate(HEMA)dissolved in tert-butyl alcohol(TBA)was developed.The polymerization of the HEMA-TBA gelcasting system,the thermal behavior of obtained green body,and the microstructures and mechanical properties of the sintered bodies were investigated by rheometer,TG-DSC,SEM and bending strength testing,respectively.The results show that,(1)10 mg/mL of the initiator(benzoyl peroxide)is the optimal amount for polymerization of this gelscasting system at 25 ℃;(2)The alumina suspension of the HEMA-TBA gelcasting system showing shear-thinning behavior is sufficiently low for gelcasting process;(3)The bending strength of porous alumina ceramic samples,whose porosities range from 42% to 56%,is from(8±0.5)to(91±4.5)MPa.

CONTROLLED SEQUENTIAL AND RANDOMRADICAL COPOLYMERIZATION OF STYRENE AND BUTYL METHACRYLATE BY ATOM TRANSFER RADICAL POLYMERIZATION

Diblock copolymers containing polystyrene (PSt) andpolybutyl methacrylate (PBMA)segnents and random coplymer of styrene (St) and butyl methacrylate (BMA) havebeen prepared by atom transfer radical polymerizanon (ATRP). Diblock copolymers ofBAN and St with predetermined molecular weight (1× 104ed.5 × 104)and narrowermolecular weight distribution(1.25～1.5) were obained The random copolymercompositions were determined by 1HNMR spectroscopy and the reactivity ratios wereevaluated by the extended Kelen-Tudos method to be γst=0.91, γBMA=0.32.