Improvement of fracture toughness and glass transition temperature of DGEBA‐based epoxy systems using toughening and crosslinking modifiers

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 KIC and the glass transition temperature (Tg) simultaneously. An amine hardener (isophorone dia...

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Bibliographic Details
Published in:Polymer engineering and science 2019-01, Vol.59 (1), p.86-95
Main Authors: Utaloff, Katja, Kothmann, Martin Heinz, Ciesielski, Michael, Döring, Manfred, Neumeyer, Thomas, Altstädt, Volker, Gorman, Irene, Henningsen, Michael
Format: Article
Language:English
Subjects:
Amines
Analysis
Bisphenol A
Block copolymers
Copolymers
Crosslinking
Curing agents
Epoxy resins
Fracture toughness
Glass transition temperature
Materials research
Mechanical properties
Nanoparticles
Organic chemistry
Phenols (Class of compounds)
Polymer crosslinking
Polymer industry
Polymers
Polytetrahydrofuran
Properties
Silicon dioxide
Stress intensity factors
Temperature
Thermodynamic properties
Toughening
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Summary: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 KIC and the glass transition temperature (Tg) 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 KIC value of the resin system DGEBA/IPD (KIC = 0.72 MPa1/2; Tg = 164°C) was achieved with the dendric polymer Boltorn P501 (10 wt%), but it decreased the Tg (KIC = 1.39 MPa1/2; Tg = 136°C). A high toughening effect with a low decrease of Tg was achieved with a combination of a self‐organized block copolymer (Nanostrength M22N) and silica nanoparticles (Nanopox F400) (KIC =1.15 MPa1/2; Tg =157°C). The KIC value of the resin system DGEBA/EMIM Ac was improved from 0.44 to 0.66 MPa1/2. 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 (KIC = 0.86 MPa1/2; Tg = 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
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.24870