A new approach to compatibilization study of EVA/PMMA polymer blend used as an optical fibers adhesive: Mechanical, morphological and thermal properties

Mechanical, morphological and thermal properties of optical fiber adhesives, based on poly(ethylene-co-vinyl acetate) (EVA) with 18 and 40% of vinyl acetate, polymer blend of EVA/poly(methyl methacrylate) (PMMA), and graft polymer, raw EVA-g-PMMA, prepared via in situ free radical polymerization, were studied. Extraction of PMMA homopolymer from raw EVA-g-PMMA produced purified EVA-g-PMMA, which enable quantitative determination of graft initiating centers by NMR spectroscopy. FTIR and image analysis allowed determination of the graft content/level in purified EVA-g-PMMA. Grafting effect to compatibilization efficiency in EVA-g-PMMA was monitored by image analysis of gelation processes and determination of wetting angle. Single lap joint of adhesives/optical fibers were subjected to adhesive testing before and after aging on 60°C for 60h and 120h. Thermogravimetry coupled with mass spectrometry showed different thermal stability and degradation pathways of adhesives, and reduced the degree of deacetylation of thermally treated EVA-g-PMMA adhesive. DSC analysis showed higher thermal stability of EVA-g-PMMA adhesive. Better mechanical properties of EVA-g-PMMA, i.e. 62.4% higher Charpy impact strength value in relation to EVA, was obtained.