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Improvement of fracture toughness and glass transition temperature of DGEBA ‐based epoxy systems using toughening and crosslinking modifiers
Author(s) -
Utaloff Katja,
Kothmann Martin Heinz,
Ciesielski Michael,
Döring Manfred,
Neumeyer Thomas,
Altstädt Volker,
Gorman Irene,
Henningsen Michael
Publication year - 2019
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.24870
Subject(s) - diglycidyl ether , materials science , epoxy , glass transition , curing (chemistry) , bisphenol a , fracture toughness , isophorone , diamine , composite material , copolymer , polymer chemistry , polymer
Several toughening and crosslinking modifiers were tested in two epoxy resin systems based on the diglycidyl ether of bisphenol A (DGEBA) with the objective to improve the critical stress intensity factor K IC and the glass transition temperature ( T g ) simultaneously. An amine hardener (isophorone diamine (IPD)) and a homopolymerization initiator (1‐ethyl‐3‐methylimidazolium acetate (EMIM Ac)) were used as curing agents. The highest effect on the K IC value of the resin system DGEBA/IPD ( K IC = 0.72 MPa 1/2 ; T g = 164°C) was achieved with the dendric polymer Boltorn P501 (10 wt%), but it decreased the T g ( K IC = 1.39 MPa 1/2 ; T g = 136°C). A high toughening effect with a low decrease of T g was achieved with a combination of a self‐organized block copolymer (Nanostrength M22N) and silica nanoparticles (Nanopox F400) ( K IC =1.15 MPa 1/2 ; T g =157°C). The K IC value of the resin system DGEBA/EMIM Ac was improved from 0.44 to 0.66 MPa 1/2 . An improvement of both, the thermal and mechanical properties was established for a combination of a poly(tetrahydrofuran) as toughening modifier (PolyTHF2000) with the post‐crosslinking modifier diethylphosphite (DEP) in the resin system DGEBA/IPD ( K IC = 0.86 MPa 1/2 ; T g = 180°C). A system with chemical linkages between both modifiers was investigated for comparison but yielded inferior results. POLYM. ENG. SCI., 59:86–95, 2019. © 2018 Society of Plastics Engineers