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Two series of bifunctional benzoxazines were synthesized from o - and p -hydroxybenzyl alcohols (o HBA and p HBA), three aliphatic diamines containing ether linkage (Jeffamines D230 and D400 and 4,7,10-trioxa-1,13-tridecanediamine (TTDDA)), and paraformaldehyde. The chemical structures of the benzoxazines were confirmed by 1H and 13C nuclear magnetic resonance and Fourier transform infrared (FTIR) spectroscopy. The ring-opening polymerization of the benzoxazines was studied by differential scanning calorimetry and FTIR, respectively. o HBA-based benzoxazines respectively exhibit lower onset temperatures of ring-opening polymerization than p HBA-based counterparts due to the O–H∙∙∙O intramolecular hydrogen-bonding interaction between the hydrogen of ortho -methylol group and the oxygen in oxazine ring, and o HBA-based polybenzoxazines respectively show lower glass transition temperatures (T gs) than p HBA-based counterparts due to the difference in crosslinking density caused by the steric hindrance effect of the position of methylol group on the polymerization of benzoxazine monomers. In each of the two series of benzoxazines, the onset temperature of ring-opening polymerization of D230-based benzoxazine is close to that of TTDDA-based analogue and lower than that of D400-based counterpart owing to the steric effect of the chain length and chain volume of the bridging structure between the oxazine rings on the polymerization, and the T g of D230-based polybenzoxazine is close to that of TTDDA-based analogue and much higher than that of D400-based counterpart owing to the difference in crosslinking density caused by the steric hindrance effect of the bridging structure on the polymerization of benzoxazine monomers. In addition, all the polybenzoxazines exhibit thermally induced shape memory effect. In each of the two series of polybenzoxazines, the shape recovery rate and ratio of D400-based polybenzoxazine are respectively close to those of D230-based counterpart and higher than those of TTDDA-based analogue due to the difference in network architecture. [ABSTRACT FROM AUTHOR]

Poly(benzoxazine-co-urethane) was prepared by melt-blending bisphenol-S/aniline-type benzoxazine (BS-a) with isocyanate-terminated polyurethane (PU) prepoly-mer based on 2,4-toluene diisocyanate and poly(ethylene glycol), followed by thermally activated polymerization of the blend. The copolymerization reaction between BS-a and PU prepolymer was monitored using Fourier transform infrared spectroscopy. The morphology, dynamic mechanical properties, and thermal stability of the poly(benzoxazine-co-urethane) were studied using scanning electron microscopy, dynamic mechanical analysis, and thermogravimetry. Homogeneous morphology is shown in scanning electron micrographs of the fracture surfaces of poly(benzoxa-zine-co-urethane)s with different urethane weight fractions, and the roughness of the surface increases with urethane content increasing. Correspondingly, a single glass transition temperature ([T.sub.g]) is shown on the dynamic mechanical analysis curves of the poly(ben-zoxazine-co-urethane)s, and the [T.sub.g] is higher than that of the polybenzoxazine. With increase in the urethane content, the [T.sub.g] and water absorption of poly(benzoxa-zine-co-urethane) increase, whereas the storage modulus and thermal stability decrease. POLYM. ENG. SCI., 53:2633-2639, 2013. © 2013 Society of Plastics Engineers, INTRODUCTION Benzoxazines is a newly developed class of thermosetting phenolic resins, and they can be used as matrix resins for high-performance composite because their corresponding polybenzoxazines possess many unique advantages, [...]

A series of poly (acrylic acid) copolyester/graphene latices were prepared by in-situ polymerization using graphene, acrylic acid (AA), methyl acrylate (MA) and ethyl acrylate (EA) as raw materials, and a composite electrode sheet was prepared by a fabric impregnation method. The effects of graphene and monomer contents on the electrical conductivity, flexibility, mechanical properties and electroencephalography (EEG) monitoring performance of the composite electrode sheet were investigated by using Ohm meter, differential scanning calorimetry, universal material testing machine and EEG tester, and its morphology was observed by scanning electron microscopy. The results indicated that the prepared composite electrode sheet exhibited good flexibility at a graphene content of 46. 5 wt%, a reaction temperature of 80 °C, a reaction time of 3 h, and an AA/MA/EA volume ratio of 0.2/1/1.8. In this composite electrode sheet, and the fabric was made from the non-woven fabric impregnated by copolyester emulsion. This composite electrode sheet exhibits good electrical conductivity and mechanical strength at room temperature and is suitable for the use in EEG monitoring, and its signal intensity and stability for EEG is similar to the commercial Ag/AgCl electrode. There is no conductive paste needed for this composite electrode, so it is more convenient for use without any skin contact. [ABSTRACT FROM AUTHOR]