Vulcanization ingredients

Vulcanizing latex adhesives are used in the manufacture of textiles, rugs and carpets. The vulcanizing ingredients are sulphur, zinc oxide and accelerators (for example, zinc dibutyldithiocarbamate and zinc mercaptobenzothiazole to produce vulcanization at room temperature). 

Fig. 8 Stress-strain plots of layered-silicate-filled NBR cured by sulfur and peroxide (a), sulfur in the presence of different zinc organic salts (b), and peroxide in the presence of different vulcanizing ingredients (c)...

The compounding of CR with fillers and vulcanization ingredients was done by a laboratory size open two-roll mixing mill. All the weights are given in parts per hundred parts of rubber and the recipe for the CR compounds is given in Table 4. 

Fig. 34 WAXD patterns of 5 phr organoclay-filled peroxide-crosslinked NBR in the presence of different vulcanizing ingredients...

The results demonstrate the versatility of plasma polymerization of various monomers onto rubber fillers and vulcanization ingredients. The largest effects are seen in blends of different rubbers with unequal polarities. Substantial improvements in mechanical properties are seen in comparison with the use of unmodified fillers and curatives. 

In dissimilar rubber/rubber blends, vulcanization ingredients also preferentially end up in only one of the phases, resulting in overcuring of this phase and under-curing of the other one. An example of this effect is the solubility of insoluble sulfur, which is much lower for NBR than for SBR and EPDM. 

The various substrates, monomer gasses or vapors, rubbers, and vulcanization ingredients are given in Table 1. The materials were used as received, without further purification. 

S-SBR 25% styrene, 75% butadiene Vulcanization ingredients and coupling agent Buna VSL 5025-0 HM Lanxess... 

The production of foamed rubber by whipping a latex is known for a long time. Rubber mattresses are still being made in this way. The latex is whipped into a foamy substance and then poured into a mould. The water is evaporated, and the rubber is vulcanised with the aid of vulcanization ingredients (sulphur etc.) added before to the latex. The density of a rubber latex foam for mattresses is about 70 kg/m3. 

The R trapping also represents alternatives to the formation of so called unextractable nitrogen observed in aged vulcanizates, and formed as a result of reactivity with vulcanizing ingredients, aldehydic end groups or zwitterions (for mechanistic details see Sect. 5). 

Vulcanizing ingredients (accelerator + snlfnr, sulfur donor) -i- activators gives ... 

Premature vulcanization of a rubber compound (called scorch) can occur if the reaction temperature of the vulcanizing ingredients is reached before the desired time. If this temperature is reached in the mixing process before the proper viscosity and level of dispersion is obtained, then the addition of accelerators and vulcanizing agents will cause scorchiness and poor processability. 

Solution procedure, (i) metal alkoxide and the rubber are dissolved in a common solvent (ii) water, sol gel catalyst and vulcanization ingredients are added (iii) sol-gel process is performed, at given temperature and time (iv)... 

The distribution of soluble compounding ingredients, especially curatives, may significantly infiuence the performance of the vulcanized product. Diffusion of common vulcanizing ingredients, such as sulfur, tetramethylthiuram disulfide (TMTD), benzothiazole disulfide (MBTS), and diphenylguanidine (DPG) occurs... 

The approach used was to prepare a filler (e.g., polystyrene) of desired particle size by emulsion polymerization, to blend it in desired proportion with an SBR latex containing the necessary vulcanizing ingredients, to coagulate the blended, compounded latex and to vulcanize the rubber at temperatures well below the softening point of the polymeric filler. 

The major use of vulcanizing latex adhesives is in the manufacture of textiles, rugs and carpets, and closely allied products such as rubberized hair. As in many other latex applications, ultraaccelerators are used to effect vulcanization. The materials used must be stable in alkaline dispersions, although they need not be active, since if the alkali is ammonia it will normally be removed early in the drying/vulcanization process. The vulcanization ingredients, sulfur, zinc oxide, and the insoluble accelerators must be added as dispersions in water, and these are conveniently prepared at 50% solids and stabilized by an anionic surfactant. Such dispersions may be made by ball-milling or may be easily purchased premade from specialist suppliers. Soluble accelerators can be added as solutions directly to stabilized latex, but the solutions have a much more limited life than do dispersions. 

Nitrile-phenolics are formulated as two-part adhesives dissolved in ketonic, chlorinated or, most frequently, in blended solvents. Some one-part materials are available which do not contain vulcanizing ingredients for the nitrile rubber but rely on a novolac resin with the addition of hexamine to introduce some cross-linking into the rubber. 

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