はく離のレオロジー : 分散形のレオロジー, その他

概要

論文の詳細を見る
The dependence of the peeling strength on the peeling rate is treated in this paper rheologically. First we showed experimentally that the time-temperature superposition principle is applicable to the S-type curve of the peeling strength vs. the rate for the amorphous polymer films (Vinylite) of various plasticizer (DBP) contents above glass transition temperature (T_g). The dependence of the shift factor a_T on the temperature obeyed the W. L. F. equation giving reference temperature T_s considerably lower than T_g+50^o, where T_g is measured dilatometrically. This means that the fractional free volume at T_g is larger than 0.025, in our case showing 0.037. This discrepancy is explained by the theory of Ferry and Stratton on the increase of fractional free volume due to the extension of polymers of Poisson's ratio less than 1/2. the apparent activation energy at T_s evaluated from the dependence of log a_T on temperature, are 46.5-33kcal/mol for samples of plasticizer contents 0-40%, which are reasonable values for the viscous flow of the polymer segments. From these experimental results we conclude that the dependence of the peeling strength on the rate is substantially rheological in character, and that the course of peeling is not governed by the electrostatic mechanism as proposed by Deryagin et al. Secondly, we derived a theoretical formula relating to the peeling strength to the rate of peeling in adhesive tapes assuming that the adhesive layer is deformed locally only at the peeling end, and its rheological behavior is described by the simple Voigt model. It is also assumed for simplicity that the shape of the bend at the peeling end is regarded as a part of a circle of radius R, which is determined by the peeling force P as R=√<E_0I/P>, and that the deformation is vertical to the adherend surface. If the peeling proceeds steadily with velocity u, we may represent the initial and proceeding stage after time t of peeling with two circles whose centers are at (O, R) and (vt, R). Then the elongation of the adhesive Layer at the origin, y, is given as a function of v, R, and t, with its time derivative, dy/dt, as a function of v, R, and y. Introducing this into Voigt's equation and integrating the equation dW=fdy from f=0 to f=f_b where f_b means the critical surface force, we obtain work of deformation, W_d, at the adhesion break. In the work of deformation, elastic energy W_e must be reserved. Put W'_d=W_d-W_e, then the sum of W_a, work of adhesion, and W'_d equals to the work done by the applied force, that is W_a+W'_d=P(1-cosθ), where θ is peeling angle. Carrying necessary calculation with some reasonable approximations, we obtain the following equation in the case of L-peeling (θ=π/2), P-C_1P^<1/4>_v+C_2P^<1/2_v^2=W_a, C_1=2√<2h^<1/2>>/3(E_0I)^<1/4>・(f_b/E)^<3/2>η, C_2=2/(E_0I)^<1/2>・(η/E)^2f_b, where E_0 is Young's modulus of polymer film which determines the curvature at the peeling end, I, its moment of inertia , h, the thickness of the adhesive layer, η and E, viscosity coefficient and Young's modulus of the adhesive. this equation represents well the S-type curve of log P vs. log v expert that the theoretical slope of the curve is rather steeper than the observed one around the inflexion point. The time-temperature superposition principle is also confirmed from this equation. The exact derivation of the relation has also been discussed without making any assumption.
社団法人日本材料学会の論文
1964-05-15

著者

畑敏雄
東京工業大学

はく離のレオロジー : 分散形のレオロジー, その他

スポンサーリンク

概要

著者

関連論文

スポンサーリンク