Plastic deformation in the form of slip lines is observed in front of notches in pure epoxy and robber-toughened epoxy specimens under four-point bending. In contrast to the case for pressure-insensitive materials, the angles between two families of slip lines emanating from notch surfaces are not 90°: they are smaller than 90 ° under tension, but they are larger than 90 ° under compression. Fo...

The molecular mobility related to the glass transition and secondary relaxations in a hyperbranched polyethyleneimine, HBPEI, and its relaxation behaviour when incorporated into an epoxy resin matrix are investigated by dielectric relaxation spectroscopy (DRS) and dynamic mechanical analysis (DMA). Three systems are analysed: HBPEI, epoxy and an epoxy/HBPEI mixture, denoted ELP. The DRS behavio...

The use of epoxy resins in metal structures for adhesive reasons is getting wider. Epoxy resins possess enhanced mechanical, chemical and physical properties, i.e. increased shear and compression strength, resistance in solvents, as well as at high temperatures. Tensile tests were carried out with standard aluminium tension specimens glued with epoxy resins. The thickness of the glue and the ac...

A series of metal-containing epoxy polymers have been synthesized by the condensation of epichlorohydrin (1-chloro-2,3-epoxy propane) with Schiff base metal complexes in alkaline medium. Schiff base was initially prepared by the reaction of 2,6 dihydroxy 1-napthaldehyde and o-phenylenediamine in 1 : 2 molar ratio and then with metal acetate. All the synthesized compounds were characterized by e...

OBJECTIVES Epoxy adhesives contain organic solvents and are widely used in industry. The hazardous effects of epoxy adhesives remain unclear. The objective of this study was to investigate the risk of hearing loss among workers exposed to epoxy adhesives and noise. DESIGN Cross-sectional study. METHODS For this cross-sectional study, we recruited 182 stone workers who were exposed to both e...

Irradiation of terminal aromatic γ,δ-epoxy ketones with a 450 W UV lamp led to Norrish type II cyclization/semi-pinacol rearrangement cascade reaction which formed the benzocyclobutanones containing a full-carbon quaternary center, whereas irradiation of substituted aromatic γ,δ-epoxy ketones led to the indanones through a photochemical epoxy rearrangement and 1,5-biradicals cyclization tandem ...

The preparation of some ring A and B epoxy steroids derived from testosterone, pregnenolone and epiandrosterone using m-chloroperbenzoic acid is described. The biotransformation of the epoxy products by the fungus Mucor plumbeus are performed. The introduction of the epoxy group into the steroids moiety has affected the biotransformation results and gave only hydrolyzed products.

(3Z,6Z,9S,10R)-9,10-Epoxy-3,6-henicosadiene (1) and (3Z,6Z,9S,10R)-9,10-epoxy-1,3,6-henicosatriene (5), pheromone components of the female fall webworm moth (Hyphantria cunea Drury), were synthesized by starting from (2S,3R)-2,3-epoxy-4-t-butyldimethylsilyloxy-1-butanol (8). Epoxide 8 was prepared by employing lipase-catalyzed asymmetric acetylation of ( )-8 as the key optical resolution step.

costs and train operations. The impact is sometimes magnified by imperfect or poorly understood techniques for predicting and detecting IJ failures. A common factor in many failures of bonded IJs is a tendency for the epoxy to come debonded from the rail or joint bar near the center of the joint (2). The debonded region starts small but grows with time and traffic, spreading outward toward the ...

Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarbo...