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Different amounts of multiwalled carbon tubes (MWCNTs) were incorporated into an epoxy resin based on diglycidyl ether of bisphenol A and both epoxy precursor and composite were cured with 4,4′-diamino diphenyl sulfone. Transmission and scanning electron microscopy demonstrated that the carbon nanotubes are dispersed well in the epoxy matrix. Differential scanning calorimetry measurements confirmed the decrease in overall cure by the addition of MWCNTs. A decrease in volume shrinkage of the epoxy matrix caused by the addition of MWCNTs was observed by pressure-volume-temperature measurements. Thermomechanical and dynamic mechanical analysis were performed for the MWCNT/epoxy composites, showing that the T g was slightly affected, whereas the dimensional stability and stiffness are improved by the addition of MWCNTs. Electrical conductivity measurements of the composite samples showed that an insulator to conductor transition takes place between 0.019 and 0.037 wt % MWCNTs. The addition of MWCNTs induces an increase in both impact strength (18%) and fracture toughness (38%) of the epoxy matrix with very low filler content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

A comparative study of the influence of 2-(10-oxo-10H-9-oxa-10λ5-phosphaphenanthrene-10-yl)-benzene-1,4-diol (DOPO-HQ) and 2-(2,8-dimethyl-10-oxo-10H-10λ5-phenoxaphosphine-10-yl)- benzene-1,4-diol (DPPO-HQ) on their ability to form polysulfones (PSU) with 4,4'-difluorodiphenylsulfone (DFDPS) as well as the properties of the aromatic phosphorus-containing polysulfones (P-PSU) is reported. These properties are also compared to bisphenol A-based polysulfone. Both diols have the phosphorus unit as substituent and differ in the number of oxygen atoms within the environment of the phosphorus changing from DOPO-HQ (phosphinate structure, Ar2OP(=O)) to DPPO-HQ (phosphine oxide structure, Ar3PO). The nucleophilic aromatic polycondensation was carried out successfully using both phosphorus-containing aromatic diols instead of bisphenol A and was followed by ATR-FTIR in-line monitoring. The use of DPPO-HQ decreased the number of side reactions and enhanced slightly the molecular weight. The thermal stability of DPPO-HQ-based PSU is slightly better than DOPO-HQ-based PSU. Thermal decomposition schemes for PSU and for both P-PSUs are proposed based on thermogravimetric analysis and Pyrolysis GC-MS results. [ABSTRACT FROM AUTHOR]

As a method of compatibilization of immiscible polyether ether ketone (PEEK)/polysulfone (PSU) blends, the addition of segmented PEEK/PSU block copolymers based on amorphous bisphenol A-containing PEEK was studied. This approach was evaluated for blends consisting of PEEK and PSU homopolymers with different molecular weights and different amounts of compatibilizers (segmented PEEK/PSU block copolymers and reactive end-functionalized PEEK and PSU oligomers). The compatibilizers were added under varying melt-processing conditions and effectively allowed the homopolymers to interact with the segmented block copolymers in the blend. The influence of the compatibilizers on the phase behavior was examined in both binary and ternary blends. Interactions in the amorphous phase, which effectively induce an enhancement of the toughness properties of the final product, could be detected. [ABSTRACT FROM AUTHOR]