کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5186753 | 1502552 | 2008 | 8 صفحه PDF | دانلود رایگان |
Improvements in mechanical properties at low temperatures are desirable for epoxy resins such as diglycidyl ether of bisphenol A (DGEBA) that are often used in cryogenic engineering applications. In this study, a hydroxyl functionalized hyperbranched polymer (H30) is employed to improve the mechanical properties of a DGEBA epoxy resin at liquid nitrogen temperature (77Â K). The results show that the tensile strength, failure strain (ductility) and impact strength at 77Â K are simultaneously improved by adding a proper content of H30. The maximum tensile strength at 77Â K is increased by 17.7% from 98.2Â MPa of pure epoxy resin to 115.6Â MPa of modified epoxy system for the 10Â wt% H30 content. The failure strain at 77Â K increases consistently with the increase of H30 content. The maximum impact strength at 77Â K is attained by introduction of 10Â wt% H30 with an improvement of 26.3% over that of pure epoxy resin. For the purpose of comparison, the mechanical properties of modified epoxy resins at room temperature (RT) are also investigated. It is interesting to note that the impact strength is not lower at 77Â K than that at RT for the modified systems. Moreover, the glass transition temperature (Tg) is not reduced by the addition of H30 in appropriate amounts.
Journal: Polymer - Volume 49, Issues 13â14, 23 June 2008, Pages 3168-3175