Surface treatments vulcanization

Adhesion of mbber is limited because of its inherent nonpolar nature and the presence of additives in formulation (processing oils, moulding agents, antiozonant waxes, vulcanization aids). Although, unvulcanized mbbers are somewhat less difficult to bond, most of the mbbers used in industry are vulcanized mbbers. To improve their adhesion, a surface treatment is always necessary. 

The application of surface treatments to mbbers should produce improved wettability, creation of polar moieties able to react with the adhesive, cracks and heterogeneities should be formed to facilitate the mechanical interlocking with the adhesive, and an efficient removal of antiadherend moieties (zinc stearate, paraffin wax, and processing oils) have to be reached. Several types of surface preparation involving solvent wiping, mechanical and chemical treatments, and primers have been proposed to improve the adhesion of vulcanized SBR soles. However, chlorination with solutions of trichloroisocyanuric acid (TCI) in different solvents is by far the most common surface preparation for mbbers. 

In the past, BCME was used for crosslinking of cellulose, preparation of styrene and other polymers, surface treatment of vulcanized rubber to increase adhesion, and in the manufacture of flameretardant fabrics (EPA 1980a). These applications have been discontinued, and no uses of BCME other than as a nonisolated intermediate were identified. 

There are certain technical limitations in the devulcanization of rubbers, and vulcanization is, in fact, not truly reversible (Pryweller, 1999). The partial devulcanization of scrap rubber will result in a degradation of physical properties. In many cases, this may limit the amount of substitution levels in high-tech applications such as passenger tires. But it can provide the compounder of less stringent products with an excellent low-cost rubber that can be used as the prime rubber or at very high substitution levels. According to Franta (1989), reclaim cannot be used for tread compounds in tires because every addition may decrease their resistance to wear. However, this statement has not been checked in case rubber devulcanized without an addition of chemicals. Considerable amounts of reclaim are consumed for carcasses of bias ply tires for cars if the compounds are of NR for carcasses of radial tires no reclaim is added. On the other hand, reclaim is added to compounds for bead wires and it may also be added to sidewalls. Within the framework of direct recycling options a number of applications for GRT outside the rubber industry have been proposed. Such applications include the use as a tiller in asphalt for the surface treatment of roads and as a rubberized surface for sport facilities. 

CB, and in particular Vulcan XC-72, is the standard support material in fuel cell research. Therefore, it is hardly surprising that most recent publications do no longer focus on ways to describe, analyze, and optimize the support, but rather report on strategies to, for example, increase the dispersion of the catalytically active metal nanoparticles on the carbon surface by various treatments [43-47]. Apart from that, also the investigation of CB composites, such as CB blended with CNT [48] and CB/reduced graphene oxide [49], came into the focus of recent fuel cell research, as well as its application in the microporous layer (MPL) of the GDLs, which are not subject of this chapter [50, 51]. In addition, the comparison of low-surface-area Vulcan XC-72 with high-surface-area black pearls or Ketjen-black with respect to their electrochemical properties, capacitive behavior [52], and durability [53] has been a frequent subject of recent publications. 

Table 4.9 Butt joint strengths (MPa) of rubber/metal joints for various vulcanized rubbers and surface treatments [76] ...

Depending on fashion, each year different materials have been and are currently used in the manufacturing of shoes, ranging from rubber soles (vulcanized styrene-butadiene rubber (SBR), thermoplastic rubber, EPDM) to different polymers (leather, polyurethanes, ethylene-vinyl acetate (EVA) copolymers, polyvinyl chloride (PVC), polyethylene, Phylon). To produce adequate adhesive joints, surface preparation of those materials is required (see part B Surface treatments). Surface preparation procedures for these materials must be quickly developed and the validity of these treatments is generally too short. Several procedures have been established to optimize the upper to sole bonding, most of them are based in the use of organic solvents. Due to environmental and health issues, solvents should be removed from the surface preparation procedure and several environmental friendly procedures for the surface preparation of several materials have been proposed. 

Rubber soles are by far the most common materials in shoe industry. Vulcanized or unvulcanized (thermoplastic) rubber soles are used. In general, bond is produced with one-or two-component polyurethane adhesives, and a surface treatment is always required to produce good adhesive joints. 

Cincinnati, Oh., 17th.-19th. Oct. 2000, paper 91 EFFECT OF CBS SURFACE TREATMENT ON ITS REACTIVITY IN RUBBER VULCANIZATION... 

Romero-Sanchez M.D., Pastor-Bias M.M., Martm-Martmez J.M., Zhdan P.A., and Watts J.M., 2001, Surface modifications in a vulcanized rubber using corona discharge and ultraviolet radiation treatments, J. Materials Sci., 36(24), 5789-5799. 

From the plots of BET specific surface areas as a function ofheat-treatment temperature for both Vulcan XC-72R and Shawinigan acetylene black, shown in Fig. 10, it is obvious that the latter black has experienced a much higher temperature than that for Vulcan XC-72R. It is well known that Shawinigan acetylene black is formed at a high temperature, which leads to significant surface area diminution. 

The efficiency of vulcanization and structure formation of rubber concrete can be considerably increased by supplementary thermal treatment of the outside of the covering, thereby creating a more uniform thermal field along the surface and volume of the heated article. 

Efforts to bond rubber to metal without the use of metal plating led to what is believed to be the first research efforts in surface preparation prior to adhesive bonding. Strong and durable bonds of rubber to metal were necessary for rubber shock mounts for automobiles in the late 1920s, but they were limited to proprietary formulations used on specific metals. In 1927 solvent-based thermoplastic rubber cements for metal-to-rubber bonding were prepared from rubber cyclized by treatment with sulfuric or other strong acids. With these rubber cements strong bonds could be made to either vulcanized or unvulcanized rubber. 

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