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This study assesses the progression of damage occurring on glass fiber reinforced polyester composite specimens using acoustic emission (AE) parameters. Its aims are to improve understanding of the particular characteristics of AE signals; and also to determine the relationship between AE signals and the failure of the material. Time and frequency domain trends were analysed at four different applied loads (60.97, 67.75, 74.52 and 81.30 MPa) representing 45–60% of the ultimate tensile strength of material. The relevant AE parameters were analysed both in the early stages of the test and as the material neared the fracture zone. The results showed a high degree of correlation between the root mean square and number of hits AE values and the number of cycles to failure, of 92.99 and 92.19%, respectively. This correlation, as well as AE basic parameters, suggests that AE can be a valuable tool to predict the fatigue life and detect the onset of damage in such composite materials. [ABSTRACT FROM AUTHOR]

Poly(ether-imides) were prepared by two simultaneous reactions, that is, Diels-Alder reaction and nitro displacement reaction. Thus 3-nitrophthalic anhydride was reacted with furfuryl amine and the resultant amic acid was then reacted with three bismaleimides (2a–c) and disodium salt of bisphenol–A. The obtained polymers were treated with acetic anhydride to form cyclic imide, as well as aromatization of Diels-Alder adduct. The poly(ether-imide)s were characterized by IR spectral studies and theromgravimetry. A “in situ” polymerization on glass fibers was also carried out and the laminates were characterized by physical, mechanical, and chemical properties. [ABSTRACT FROM AUTHOR]