Rubber compounding categories

For some applications, such as when it is necessary to dissolve or solvate rubbers, or rubber compounds to form doughs and solutions it is desirable to use a machine in this category. Various types of machines can be used to produce the required form. Grinders are also used to reduce scrap vulcanisate to form a rubber crumb for purposes of working this waste product back into cheap compounds, or prior to reclaiming rubber by chemical processes. 

Various processability tests are used to predict how well a rubber compound will process. However the process" can vary greatly. Table 1 shows the diverse categories of rubber processes and some of the quality characteristics and concerns associated with each process. The natures of these processes vary because of differences in applied shear rates, temperatures, residence times, etc. Changing a given compound property can improve performance in one or more of these processes but could hurt the performance in another process. This is why it is important to look at all processes in a manufacturing operation when implementing compound changes. 

Other types of process aids available to the rubber compounder to assist in various processing problems essentially fall into the following main categories. 

Blend of (1) and (2) type categories mostly include the modification of engineering thermoplastics with another thermoplastic or rubber. PS-EPDM blends using a low-molecular weight compound (catalyst) Lewis acid have been developed [126]. Plastic-plastic blends, alloys of industrial importance, thermoplastic elastomers made by dynamic vulcanization, and rubber-rubber blends are produced by this method. 

Aliphatic and alicyclic amines form one of the most extensively used categories of compounds in a variety of manufacturing industries. These compounds are first-phase materials for chemical synthesis, intermediates, pharmaceuticals, pesticides, soil sterilizers, and several kinds of solvents, rubber products, rocket propellants, and plastic monomers. This chapter discusses the safety and toxicity of selected compounds handled by workers in different industries. More information and extensive literature are available in several study reports on members of this important group.31,32... 

Processing oils in a rubber formulation serve primarily as a processing aid. Oils fall into one of three primary categories paraffinic, naphthenic, and aromatic. The proper selection of oils for inclusion in a formulation is important. If the oil is incompatible with the polymer, it will migrate out of the compound with consequent loss in required physical properties, loss in rubber component surface properties, and deterioration in component-to-component adhesion, as in a tire. The compatibility of an oil with a polymer system is a function of... 

Among the particulate organic fillers, wood meal is the most important material for use in thermoplastics, in particular PP. For curable molding compounds, powdered cellulose is also in this category. These finely powdered materials are actually fibrous, finely ground and specially conditioned products based on spruce or beech wood or cotton. Others include wood granulate, sawdust, shell and seed meal and, already mentioned in relation to impact modifiers, natural rubber. 

The elastomers and elastomer blends used in tire compounds, and particularly tread compounds, are thus equally important to the structural design parameters of the tire (Table 4.7). A properly designed tread compound will ensure the tire can meet its performance targets. Tread compounding materials fall into one of five general categories polymers, fillers, protectants, vulcanization system, and various special purpose additives. Elastomers for tread compounds are typically natural rubber (NR), styrene-butadiene rubber (SBR), polybutadiene (BR), and in some instances isobutylene based polymers for winter and special performance tires. 

---