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Rheologica Acta

, Volume 35, Issue 4, pp 321–328 | Cite as

Curing effects on viscosity of reactive epoxy resin adhesives

  • D. Hesekamp
  • M. H. Pahl
Original Contribution

Abstract

The influence of temperature and the extent of curing on the viscosity of a ,reactive epoxy resin adhesive is described and a mathematical model for the behavior is introduced. The temperature dependence of viscosity can be described by the WLF equation. The parameters required for the WLF equation are obtained from experiments in the temperature range where the crosslinking reaction has not yet been initiated. The viscosity and glass transition temperature increase with increasing curing. The glass transition temperature can also be described with an equation of the WLF type. Kinetic experiments on the epoxy resin adhesive enable a time and temperature dependent description of the extent of curing with a series reaction of the type A→B→C, where each partial reaction is of order n. The viscosity model and reaction kinetics enable calculation of the viscosity as a function of time and temperature, which agrees well with the experimental data.

Key words

Epoxy resin adhesive viscosity curing chemorheology reaction kinetics 

List of symbols

aN

Viscosity shift factor

aT

Temperature shift factor

ax

Glass transition temperature shift factor

b1

Constant for crosslinking effects

b2 °C

Constant for crosslinking effects

c2

WLF constant

c2 °C

WLF constant

cA, cB, cC

Concentrations of A, B and C

f

Ratio of the reaction rate of series reaction

g1,g2

Constants of glass transition temperature equation

k01, k02s−1

Pre-exponential factor for the reaction rate constants

n1,n2

Reaction orders

s

Scan numbers of various DTA analyses

t s

Time

D mm

Diameter

E1,E2 J/mol

Activation energies

H mm

Gap

M g

sample weight for DTA analysis

MA g/mol

Molecular weight of hardener

ME g/mol

Molecular weight of epoxy resin

Q J

Heat

\(\dot Q\) W

Heat flux in DTA analysis

R 8.314 J/(mol·K)

Gas constant

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Copyright information

© Steinkopff Verlag 1996

Authors and Affiliations

  • D. Hesekamp
    • 1
  • M. H. Pahl
    • 1
  1. 1.Universität-GH PaderbornPaderbornGermany

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