Лако-красочные материалы — производство

Perhaps the most apt definition of analysis of adhesives is their qualitative and quantita­tive characterization. Since the early days of adhesive development, the elementary che­mical analysis of adhesives has provided valuable information on the structure and purity of materials. Chemical methods of analysis are simple and cheap but labor intensive. The use of such techniques […]

David N.-S. Hon Clemson University, Clemson, South Carolina, U. S.A. I. INTRODUCTION Adhesives now form an inextricable part of modern life. In fact it is difficult to imagine our everyday existence without these bonding substances. Consider packaging, building, auto­mobiles, dentistry, medicine, consumer goods, and food industries—all these activities rely heavily on adhesive materials. Use of […]

Although the degradation of a bond is likely to be inevitable, there are means by which to slow down the process; some of which were discussed above. For convenience of the discussion, these methods can be classified as environment, materials, and design related. Changing the environment to which a bond is exposed is probably the […]

The stresses that a joint experiences during environmental exposure also influence its durability, i. e., it exhibits either decreased lifetime or decreased residual strength [1,7,10,107]. As with moisture, there may be a critical stress level below which failure does not occur [108,109] or is not accelerated (depending on the moisture level). The type of stress […]

The effects of water and temperature on the adhesive itself are also of utmost importance to the durability of bonded structures. In the presence of moisture, the adhesive can be affected in a number of ways, depending on its chemistry and how rapidly the water permeates through and causes significant property changes [51,86-88]. The potential […]

The adherend often establishes ultimate joint durability. The morphology of its surface determines the degree of physical bonding (mechanical interlocking) with the polymer and its chemistry, in part, determines the degree and type of chemical bonding. Furthermore, the stability of the adherend and its surface determines the ultimate limit of durability. Once the adherend becomes […]

The adherend, adhesive, and interphase between them are major factors in determining bond durability. For example, the simple disruption of the dispersive forces already described indicates that joints made with composite adherends will be inherently more stable than those made with metallic adherends. To increase durability, most metallic and many polymeric adherends undergo surface treatments […]

As already mentioned, moisture is the bane of most adhesive bonds. It is nearly impossible to keep water from a bond exposed to the outside environment [14]. Water can readily diffuse through the adhesive or the adherend, if it is permeable, as a composite might be. Moisture can also wick or travel along the interface […]

Guy D. Davis DACCO SCI, Inc., Columbia, Maryland, U. S.A. I. INTRODUCTION Although obtaining high initial bond strength is relatively easy, maintaining good bond durability in aggressive environments is comparatively more difficult. The most impor­tant factor leading to bond degradation of most materials is moisture. Moisture is pervasive over much of the world and is […]

One major cause of adhesive tape failure is the gradual disentanglement of the adhesive polymer system under slight but prolonged shear stress. While the standard shear stress test under static load (see Section II. B) is the accepted test method to evaluate this, the nature of the results, which could be in tape movement, time […]