Rubber research approach

The approach that has been used in our laboratories for synthetic rubber research for improved tire tread composition is shown in Figure 1. 

The first move in this direction was to improve the weatherability of impact-resistant polystyrene. Because polybutadiene, the most widely used rubber in impact-resistant polystyrene, is unsaturated, it is sensitive to photooxidation, and impact-resistant polystyrene is therefore not suitable for outdoor applications. A saturated rubber might be able to help here. In the ABS sector this has been successfully tried out with acrylate rubber (77) and EPDM (78, 79), and the latter has also been used in impact-resistant polystyrene (80, 81) This development has elicited satisfactory responses only in certain areas and more work still has to be done. For instance, attempts have been made to improve resistance to weathering by using silicone rubber (82 ). This approach is effective, but economic factors still stand in its way. Further impetus may also be expected from stabilizer research. Hindered secondary amines (83), to which considerable attention has recently been paid, are a first step in this direction. 

As World War II approached, Germany and the USSR worked frantically to be free from outside need of rubber. The United States by comparison were conducting research in a number of areas that would eventually prove useful, but had made no real push for... 

Since Meyer ) introduced the concept of kinetic molecular chain into the physics of polymers in 1932, remarkable progress has been made in the molecular-theoretical interpretation of elastic behavior of rubber vulcanizates and polymer solids in general2- ), and one can appreciate the present status of knowledge on this subject by a number of review articles and reference books. On the other hand, the phenomeno-logic approach to rubber elasticity has not aroused much interest in the field of polymer research. This is understandable because polymer scientists are primarily concerned with affairs of the molecular world. 

HIPS products however do not have sufficient impact strength for many uses. SkiHed researchers agree that HIPS with impact strength approaching 7.5 ft-lbs/inch notch can be prepared by adding more rubber. However the hardness, flexural modulus, tensile, and heat distortion temperatures are then drastically reduced. 

No percutaneous devices are completely satisfactory. Nevertheless, some researchers believe that hydroxyapatite maybe part of a successful approach. In one experimental trial, a hydroxyapatite-based percutaneous device was associated with less epidermal downgrowth (1 mm after 17 months vs. 4.6 mm after 3 months) when compared with a sUicone rubber control specimen in the dorsal skin of canines. Researchers have also investigated coatings such as laminin-5 which has been shown to enhance epithelial attachment. 

New rubber-producing crops face substantial barriers they must overcome before they can successfully enter the commercial arena (133-143). Decades of guayule research have allowed guayule to overcome these barriers and reenter the commercial arena. Researchers have investigated a plethora of approaches seeking ways... 

We believe that the approach that we have discussed should serve as a guide for the development of new tire rubber compositions of superior performance in the future. The systematic and fundamental approach in polymerization research outlined in the beginning of this paper should be emphasized. 

Various types of polymeric modifiers have been researched as possible candidates to impart impact resistance of epoxy resins. Sometimes, properties other than impact resistance are to be modified. For example, for adhesive applications, the main focus is usually on improving shear and peel strength. In these cases, epoxies blended with elastomeric nitrile rubbers (Hycar CTBN, B.F. Goodrich), phenolics, nylons (soluble types such as DuPont Zytel-61), and pol5nirethanes are commonly used. For impact modification, there are several approaches, as discussed below. 

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