Morphology profiles generated by temperature gradient in PMMA modified epoxy system

Citation
Pm. Stefani et al., Morphology profiles generated by temperature gradient in PMMA modified epoxy system, POLYM ENG S, 41(11), 2001, pp. 2013-2021
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science & Engineering
Journal title
POLYMER ENGINEERING AND SCIENCE
ISSN journal
0032-3888 → ACNP
Volume
41
Issue
11
Year of publication
2001
Pages
2013 - 2021
Database
ISI
SICI code
0032-3888(200111)41:11<2013:MPGBTG>2.0.ZU;2-3
Abstract
A diglycidyl ether of bisphenol-A (DGEBA) epoxy resin was modified with 15 wt% of poly(methylmethacrylate) (PMMA) and cured with a stoichiometric amou nt of 4,4'-diamino diphenyl methane (DDM). The reactive mixture was cured i n a heated mold with different gradients of temperature. Temperature profil es in the mold were imposed by generation of a heat. flux from the base, su pported on a hot plate, and the top, cooled with water; they were measured along the mold. Depending on the thermal history in each position of the mo ld, the competition between the phase-separation process and reaction kinet ics produces opaque or transparent zones. Phase separation can also occur i n the postcure process while the gelation does not take place before. There fore, a thermoset plate with gradient of morphology and properties was obta ined. Mass fractions of PMMA dissolved in the matrix were calculated with t he Fox equation from glass transition temperatures measured along the mold. They were related to morphologies developed during curing. The superpositi on of the phase diagrams with the conversion-temperature trajectories durin g cure permitted an explanation of the morphology gradients generated.