Papers by Keyword: Valeric Acid

Abstract: Gel casting foam is a novel method which was developed in latter 1990s for the fabrication of porous materials with regular round pores and a relatively high flexural strength. It also has the advantages of simplicity in degreasing processing and short production cycle. However, the gelating system used in this method commonly contains acrylatnide, which is toxic and sensitive to oxygen, due to which, foaming and polymerization of the substance have to be performed in an oxygen-free environment. In this work, we use agar as the gelating agent in replace of acrylatnide to prepare alumina macroporous ceramics. The effects of foaming speed, foaming time, gelating time and valeric acid on the pore diameter of the sample were investigated. Results show that the average pore diameter increasing with the foaming speed, but decreasing with the increasing foaming time. Moreover, the addition of valeric acid reduces the bubble size during foaming and increase the stability of the foams. By controlling the foaming and gelating conditions, we achieve alumina macroporous ceramics with regular round pores of over 100μm by this method.

Abstract: Poly(ether sulfone)s (PES) containing 25-75 mol % valeric acid were prepared with bisphenol A, bis(4-chlorophenyl)sulfone and 4,4-Bis(4-hydroxylphenyl)valeric acid using potassium carbonate in DMAc (dimethylacetamide) at 160 °C. Copolymers containing carboxylacid group were reduced to hydroxy group by BH₃ solution 1M in THF and NaBH4 co-catalyst. Sulfonated poly(ether sulfone)s (S-PES) were obtained by reaction of 1,3-propanesultone and the reduced copolymer (PES-OH) with potassium t-butoxide. Composite membranes were prepared with copolymers and SiO₂ nanoparticles(20 nm, 4-10 wt%). The composite membranes were cast from DMSO.A series of composite membranes were studied by ¹H-NMR spectroscopy, differential scanning calorimetry (DSC), and thermo gravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol.