Latex compounding technique

A novel NR/S102 nanocomposite was developed by combining self-assembly and latex compounding techniques. Table 18.1 lists the mechanical properties of the pure NR and NR/Si02 nanocomposites with different Si02 loadings. NR as a typical elastomer shows an excellent flexibility and low rigidity. The tensile... 

A combined self-assembly and latex compounding technique was used for preparing NR-based composites containing positively charged CNTs. " TEM and SEM indicated that the CNTs were homogeneously distributed into the NR as single tubes and their interfacial adhesion with the matrix was good. 

The latex compounding technique represents an alternative approach to the preparation of blend materials. Latex compounding is a promising method when compared, for example, to the in-situ polymerization and solution techniques that are used to produce polymer blends. Today, the procedure is becoming increasingly important as many simple polymers are available in latex form, and latex can be introduced into the polymer melt during compounding in line. In an... 

Latex compounding is also a promising method in preparing rubber-clay nanocomposites. The latex compounding technique starts with dispersing layered... 

The compounding technique for latex differs from that of dry mbber and is fundamentally simpler. A critical factor of colloidal stabiUty makes necessary that each ingredient is of optimum particle size, pH, and concentration when added as an aqueous dispersion to the latex. Rubber latex is a colloidal aqueous emulsion of an elastomer and natural mbber latex is the milky exudation of certain trees and plants that of greatest commercial importance is the... 

Rubber can be used by an engineer as a liquid latex or as a raw rubber or a vulcanized rubber. The vulcanized rubber can vary from soft gum stock through various stages of reinforced rubber (the state of which is achieved both by compounding techniques and... 

A certain proportion of fluoroelastomers is used in latex form. The compounding techniques used are similar to those used for standard latexes i.e., solid ingredients are first dispersed in water with the use of surface active agents and liquid ingredients are prepared as emulsions prior to their addition to the latex. The dispersions of solids are prepared in ball mills or high-speed mills (e.g., Kady). 

The finished dry rubber and latex based rubber products can be vulcanized by several techniques depending on the type of rubber compound (dry rubber compound/latex compound), size of the finished product, and its shape and structure. Moulded rubber products are vulcanized by press curing using compression, transfer, or injection moulding presses. The vulcanization techniques other than moulding may be grouped into batch and continuous methods. The batch methods include the use of autoclaves, hot air/gas oven, and hot liquid/ water bath. Rubber products may be vulcanized at room temperature by cold curing either by immersion of rubber products in a carbon disulphide solution of sulphur chloride (SjCy, or by exposure to its vapour. 

NR composites and nanocomposites can be fabricated by three main techniques, namely latex compounding, solution mixing and melt blending. A variety of nanofillers, such as carbon black, silica, carbon nanotubes, graphene, calcium carbonate, organomodified clay, reclaimed rubber powder, recycled poly(ethylene terephthalate) powder, cellulose whiskers, starch nanocrystals, etc. have been used to reinforce NR composites and nanocomposites over the past two decades. In this chapter, we discuss the preparation and properties of NR composites and nanocomposites from the viewpoint of nanofillers. We divide nanofillers into four different types conventional fillers, natural fillers, metal or compound fillers and hybrid fillers, and the following discussion is based on this classification. 

Since 1960, the inner core has been made from c/5-poly-butadiene by the compression moulding technique. This replaced the earlier material made from a suspension of barytes or bentonite clay in water and glycerine or the winding of rubber threads made from t /5-polyisoprene, either from latex or a dry rubber compound. A typical thread recipe is given Table 4. 

Back-coating is the major area where bromine-based flame-retardant compounds are used for textiles. This technique is applied primarily in applications such as upholstery and wall coverings. The system would comprise an FR additive with a latex binder, the latter often based on acrylic or ethylene vinylacetate. Use of vinylidene chloride-modified acrylics reduce the amount of tire-retardant additive required. 

To determine the nature of the silicon moieties in a polymer, clearly the easiest method would be a technique that provides a direct observation of the silicon atom and meaningful, interpretable information on the atom. Nuclear magnetic resonance spectroscopy tuned to the Si isotope ( Si NMR) is a tool of this nature it can directly probe the state of the silicon atom, and with it one can often readily determine the extent to which Si-O-Si crosslinks (fi-om silanol condensation), have formed. One can observe spectra of silicon-containing compounds either dissolved in a solvent or in the solid state. Liquid-state Si NMR, while the most sensitive, cannot be used quantitatively on heterogeneous systems such a latex formulations. Therefore, one must separate the liquid and solid portions of the latex (without heat, which would promote hydrolysis and condensation) and use the solid residue for the Si NMR experiments. 

The technique of paper chromatography can be extended to compounds which are sparingly soluble in water, by drying the paper and impregnating it with olive oil, silicone oil, paraffin or rubber latex. 

---