The modification of epoxy resins by means of w b o n dioxide is presented. The resulting resins contained different amounts of cyclic carbonates (1,3-diOXOlane-2one rings) instead of a part of epoxy groups. The effect of the cyclic carbonate content on viscosity, gel time, peak exotherms, and crosslinking extent of the above mentioned resins was investigated.Mechanical and thermomechanical properties of the modified resins cured with triethylenetetramine have been determined. It was found that heat-distortion temperature, impact resistance, hardness, compressive strength, and lap shear strength of the resins containing cyclic carbonates were higher than those of unmodified ones.
ZUSAMMENFASSUNG:Es wurde die Modifiierung von Dianepoxidharzen mit Kohlendioxid durchgefiihrt, wobei Produkte mit unterschiedlichen Anteilen an cyclischen Carbonaten erhalten wurden.Der Einflun der Carbonatgruppenkonzentration auf Viskositilt, Gelierzeit, Temperaturanstieg und Vernetzungsgrad bei der Hmung wurde ermittelt.Die physikalischen und thermomechanischen Eigenschaften der modifiiierten Epoxidharze, die mit Triethylentetramin vernetzt waren, wurden bestimmt. Es zeigte sich, da8 Wiirmebesttindigkeit, Schlag-und Druckfestigkeit, Hiirte und Scherfestigkeit bei den Harzen, die cyclische Carbonate enthielten, h6her waren als bei den nicht modifizierten Harzen.
Pyrotechnic flares are the traditional maritime distress signals. But flares can injure users, and they contain environmentally-hazardous materials. The U.S. Coast Guard is looking for an alternative to flares. This paper summarizes a series of experiments to determine the characteristics of conspicuous distress signals. It provides four take-aways to improve visual distress signal design.
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