1. The researches so far published on the autohesion of polymers do not make it possible to isolate the influence of the mechanical properties of rubbers, which determine the true area of contact, from the influence of polymer chain diffusion. 2. Studies of the autohesion of thin films of rubber applied by the drain-off method to quartz threads, in relation to the film thickness and contact time, show that for films less than 3.10−5 cm. thick the adhesion force is small and varies very little with contact time. This proves, on the one hand, that in this instance the contact area is small (which is obvious) and does not increase with time, and on the other hand, that diffusion processes play no part in the autohesion of films of this thickness. 3. The effects which depend on mechanical properties and on the specific interaction (per unit area of true contact) between specimens may be separated if the measured values of adhesion between all possible combinations of pairs of rubbers are compared both with their compatibilities, and with their autohesion. 4. The measurements of the adhesional shearing strength of combinations of different pairs of polymers, carried out for this purpose, showed that the results for Butyl rubber may be interpreted on the assumption that diffusion processes do not play any appreciable role and that the adhesion strength is determined both by the true contact area, which depends on the mechanical properties of the corresponding polymer specimens, and also by the influence of forces associated with the electric double layer. 5. For the other rubbers the results may be interpreted only on the assumption that diffusion processes play a significant part. For similar polarities, T12/T11>1 and for dissimilar polarities, T12/T11<1. 6. General conclusion : autohesion and mutual adhesion of rubbers is determined both by mechanical properties, which determine the true contact area, and by diffusional properties. The latter are by no means always decisive. The electric double layer also probably influences the adhesional shearing strength in some instances. It is even more likely to play a role in some cases in measurements of the work of separation of two layers.
1. The bond strength of vulcanized rubber to metal brought about by means of a bonding agent film is regulated by the ratio of the intensities of interaction of the bonding agent film with the contacting surfaces at the bonding agent- rubber and bonding agent-metal interfaces. Where these are approximately equal the bond strength is greatest. Where they differ sharply the bond strength decreases. 2. One of the factors influencing the intensity of interaction of a bonding agent film with vulcanized rubber is a reduction in the thickness of the bonding agent film ; with reduction in the thickness of the bonding agent film the intensity of interaction of the bonding agent with the vulcanized rubber falls; this is expressed in varying ways in the bond strength to metal of vulcanizates of various rubbers, causing a fall-off in some cases, and in some other cases a certain increase in the bond strength of the vulcanized rubber to the metal. 3. By means of the Lei˘konat bonding agent it is possible to bond unfilled vulcanizates based on the majority of existing polymers, whether polar or non-polar, to metal sufficiently strongly. 4. It is established that on increasing the number of polar groups in the polymer there is an increase in the intensity of interaction of the bonding agent film with the vulcanizate containing that rubber.
1. In bonding of rubber to metal by Leukonat adhesive, the type of filler present in the rubber has a very great influence on the rubber-metal bond strength. 2. Active fillers of the gas channel black type in the rubber mixture increase the interaction of the rubber with the adhesive film. 3. Inactive fillers of the thermal black type have little influence on the interaction of the rubber with the adhesive film. 4. The results of the experiments suggest that Leukonat interacts chemically with active fillers present in the rubber during the bonding process. 5. The following empirical rule is formulated: high rubber-metal bond strength is obtained if the interaction of the adhesive film with the rubber is approximately of the same degree as with the metal. This rule is supported by the experimental data. 6. Sandblasting of the metal surface increases the true contact area by a factor of 1.5\2-2, while the bond strength is increased 20 to 100 times; this indicates that qualitative changes occur in the surface on sandblasting and that the nature of the metal-adhesive interaction is greatly changed in the process. It is difficult to explain this other than on the assumption that the charge of the double layer at the metal-adhesive boundary is increased, and in consequence the work of separation of this layer at the boundary is greater.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.