Page 427 - Handbook of Adhesives and Sealants

Adhesives Families 369

TABLE 10.10 Single Part and Two Part Epoxy Adhesive Formulations with (Formula
B) and without (Formula A) Additions of CTBN. 11
Formula Formula
A B
Single Component
DGEBA (eposy reisn, EEW 190) 100 75
DGEBA/CTBN (1300X13) adduct a — 25
Tubular alumina (filler) 40 40
Cab-O-Sil (thixotroping agent) 5 5
DICY (curing agent) 6 6
Melamine (accelerator) 2 2
Lap shear at ambient temperature (MPa) 18.5 20.5
T-peel at ambient temperature (kN/m) 1.1 5.5
Two Component
DGEBA (epoxy resin) 100 77.5
Atomite whiting (CaCO 3 filler) 30 30
DGEBA/CTBN (Hycar 1300X8) adduct b — 37.5
Ancamine AD (amine hardener) 60 59.3
Lap shear strength at 40 C (MPa) 6.9 22.7
Lap shear strength at 25 C (MPa) 8.6 17.9
Lap shear strength at 75 C (MPa) 4.4 5.5
180 T-peel strength (kN/m) 0.5 5.0
a Adduct contains 40% CTBN (Hycar (1300X13).
b Adduct contains 40% rubber.

TABLE 10.11 Bulk Properties and Peel Strength of a Control Adhesive and a CTBN
Modified Epoxy Adhesive 6
Formulation A1
(control) Formulation A2
Formulation, pbw
Liquid DGEBA (EEW 190) 100 77.5
CTBN 1300 13/Epoxy adduct (EEW 340) — 37.5
CaCO3 filler
Fumed silica thixotrope 30 30
Dicyandiamide 3 3
3-phenyl-1, 1-dimethyl urea 5 6
2 2
Bulk Properties
Tensile strength, MPa 68.9 57.8
Elongation, % 2.5 3.2
Modulus, MPa 3848 2845
Tg, C (Determined via DSC) 135 129

atively high. Peel strength is also high and does not decrease rapidly
with lower temperatures. The durability of CTBN modified epoxies are
satisfactory as measured by most long term moisture tests, but it does
not match the durability of the vinyl-phenolic or nitrile-phenolic
types. 12 Nitrile-epoxy adhesive systems should not be used in marine
environments or under continuous immersion in water. 13