|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1990 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1989 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Adhesive behavior depends greatly upon physical properties of adhesives and adherents, among which chemical structures, viscoelastic properties and surface chemical properties of those are mostly important. In this study, the dependence of pressure sensitive adhesives (PSA) performances, such as adhesion (or pee-lstrength, P), tack (or rolling friction coefficient, f), both upon viscoelastic properties of adhesives and upon critical surface tension gamma _c of adherends have been investigated.
The dependence of peel strengths for a series of adherents with different gamma _c on deformation velocity (v) can be divided into two parts ; one is a peak atlower velocity side which corresponds mostly to cohesive failure in the adhesive phase, and the other is a plateau or rather a gradually increasing part which corresponds to interfacial failure. The curve shifts toward higher velocity as the relaxation time tau of the adhesive decreases. In the region where cohesive failure of the adhesives
occurs, the curve is substantially the same for all the cases, but in the region where interfacial failure occurs, the value of P is different for each adherent. It can be pointed out that lower gamma _c gives lower P at high velocity region.
Each f vs. log v curve for a seris of adherends has two peaks ; one is a peak at lower velocity side, which corresponds mostly to cohesive failure in the adhesive phase, and the other is a peak at higher velocity side, which corresponds to interfacial failure. The peak of lower velocity side is almost the same for all the adherends, but that of higher velocity side largely depends upon gamma _c of the adherends, i. e. lower gamma _c gives smaller peak at relatively lower velocity. Thus, f vs. log v curve is rather similar to P vs. log v curve, but there is a definite difference between the two ; at very high velocity f decreases drastically, while P is considerably high in the same velocity region. This difference can be attributed to the fact that f involves both bonding- and debonding- processes at the same time, but on the other hand, P involves only debonding- process.