Silane-Treated E-Glass Fiber-Reinforced Telechelic Macromer-Based Polymer-Matrix Composites

Abstract

The aim of this in vitro study was to investigate the water sorption and flexural properties of fiber reinforced composites (FRC) prepared from telechelic macromer extended urethane dimethacrylate (PEG-400-E-UEDMA)(PEG), hydroxypropyl methacrylate (HPMA) and E-glass fibers. Three experimental groups of test specimens based on poly(PEG-400-E-UEDMA-HPMA) polymer matrices and continuous unidirectional E-glass fibers were light polymerized and stored in deionized water for 0, 4, 12 or 24 weeks. The weight ratios (%) of PEG-HPMA were 27.5–70.5, 49.0–49.0 and 70.5–27.5 with an initiator-activator percentage of 1.0–1.0. After each time period of storage the water absorption and flexural properties were measured. There were six test specimens in each of the test groups (N = 6) and the specimen’s fracture surfaces were analyzed using scanning electron microscopy (SEM). All the PEG-HPMA groups exhibited the highest water absorption at the time point of two days (5.5 to 6.4 %), which thereafter decreased to the level of 3.8–4.7 % at the time point of 30 days. The flexural strength varied from dry specimens’ 128 to 283 MPa to the 30 days water-stored specimens’ of 30 to 49 MPa. The flexural modulus exhibited values from 7.9 to 14.8 GPa (dry specimens) and ca. 0.5 to 1.8 GPa after 30 days of water-storage. Both the flexural strength and modulus decrease dramatically with a longer water storage time. The SEM images showed good adhesion between the fibers and the resin matrix. In the wet conditions, the telechelic macromer based hydrophilic PEG polymer-matrix FRCs formed a plasticized composite that decreased the flexural properties.