Crosslinking blends

In another case where the twin-screw extruder was used, the rubber and plastic were melt mixed with all ingredients in a similar manner as described in blend compositions for static vulcanizations. The product was then dumped, cooled, and granulated. The premixed granules were then fed into a twin-screw extruder where a very narrow temperature profile was maintained with a relative high compression (2 1), and the screw speed was adjusted depending on the final torque and the flow behavior of the extruded stock. The stock was cured by shear force and temperature enforced by the twin-screw extruder. The dynamically crosslinked blend was taken out in the form of a strip or solid rod to determine the... 

Extending oils for compounds crosslinked with peroxides have to be carefully selected. Synthetic ester plasticisers such as phthalates, sebacates and oleates may be used in combination with crosslinking peroxides without affecting the crosslinking reaction. Some derivatives of alkylated benzenes are also known for their very low consumption of free radicals, which is clearly desirable. Mineral oil with double bonds, tertiary carbon atoms or containing heterocyclic aromatic structure may react with radicals paraffinic mineral oils are more effective than naphthenic types, which usually require extra treatment in order to guarantee optimum results when used in peroxide crosslinked blends. 

Dubois (76) described the use of crosslinked blends of PE and ESI in shoes. In blends with EVA, there is an improvement in the 23 °C compression set value alternatively a softer foam with greater resiliency can be obtained with the same compression set compared with EVA. 

The micrographs obtained from scanning electron microscopy are shown in Fig. 54 for the tensile fractured surface of 50 CR/50 XNBR self-crosslinked blend filled with 10 phr layered silicate (Fig. 54a) and for the same blend without any... 

Y.F. Xu, R.Y.M. Huang, Pervaporation separation of ethanol-water mixtures using ionically crosslinked blended poly(acrylic acid) (PAA)-nylon 6 membranes, J. Appl. Polym. Sci. 36 (1988) 1121— 1128. 

Figure 9.19 Fraction of benzene in permeate as a function of feed mixture composition for pervaporation at the reflux temperature of a binary benzene/cyclohexane mixture. A 20-qm-thick crosslinked blend membrane of cellulose acetate and polystyrene phosphate) was used [54]. Reprinted with permission from I. Cabasso, Organic Liquid Mixtures Separation by Selective Polymer Membranes, Ind. Eng. Chem. Prod. Res. Dev. 22, 313. Copyright 1983 American Chemical Society...

The IR spectra of a self-crosslinked blend of CSM/XNBR [125] following the reaction scheme (Scheme 3.3b) are presented in Figure 3.6. 

The blend of EPDM and polyacetylene was crosslinked using sulfur monochloride in a toluene solution. It should be noted that the crosslinked blend could not be doped with iodine. 

In order to improve the stability of polyacetylene, polyacetylene was blended with ethylene-propylene-diene terpolymer. Subsequently, the resulting EPDM/PA blend was crosslinked with y-radiation. Upon doping with iodine, the conductivity of the blend was found to be in the range 10-100 SI-1 cm-. It was found that the conductivity of the crosslinked blend decayed more slowly compared to that of either the uncrosslinked blend or homopolyacetylene. 

PO blends with either EPR or EPDM Spenadel [1979], using an electron accelerator (3 MeV, 25 mA) at RT, crosslinked blends of either EPR or EPDM with PE or PP (Table 11.9). In EPR, crosslinking was easier when ethylene... 

Bohm and Nelson [1981] point out that these radiation-crosslinked blends have an additional advantage they are more resistant to ozone than... 

TABLE 14.2 Selected Properties of the Dynamically Crosslinked Blends in Relations to PP/EOE Ratio... 

The process for the batoh preparation of TPVs is very similar to the one described above. The process layout for a crosslinked rubber/plastic blend preparation is the same as that for non-crosslinked blends (Figure 3.6). The prcxress steps involved in a plastic-crosslinked rubber blend prcxluction by a batch process are ... 

The process lay out will be slightly different to that used for simple non-crosslinked blends. An additional feeder is required to feed a crosslinking agent to the molten blend along the mixer (Figure 3.22). 

In the case of the peroxide crosslinked blends, the dynamic aspects probably prevent the crosslinking phase from becoming truly continuous since the material will flow. The final blend is thus thermoplastic and can be... 

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