Abstract
The curing behavior of phenolic molding compounds was studied under the heating and pressing conditions with the JSR-curelastometer and the phase angle indicator.
In addition, the viscoelastic behavior of the materials was tried to analyze during the curing process by assuming two elements Maxwell-model as the viscoelastic model, and by considering heat transfer through the material from the die. As the results, complex elastic modulus G of the material could be calculated with the following equation (Wo' is the force detected actually with the load-cell), G= (9.09X 104) Wo' and the viscoelastic properties of the material during the molding process could be approximated, with practically sufficient precision, by the simple two elements model. (Fig.11)
And the change of element-parameters (elastic coefficient G, viscosity coefficient n) with time were individually estimated with the following equations.
(t is the molding-time)
G=Gm [1-exp {-kG (t-tGO)}]
n=nm [1-exp {-kn (t-tno)}]
As a rule, kn was greater than kG and the temperature dependence of them was represented witth the following equation. (Fig. 7, Fig. 9, and Fig.10)
k=k*exp (-Ec/RoT)
Tin the above equation is the average material temperature and could be calculated with the following equation. (a is the mean thermal diffusivity)
T≅Tw-0.811 (Tw-To) exp [- (2.47 X106) αt
