Butyl rubber IIR

Butyl Rubbers (IIR/BIIR/CIIR) Designation in ISO 1629 - MR, BIIR CNR Repeat Unit (MR)... 

Butyl rubber (IIR) is derived from polyisobutylene, a polymer which is not further mentioned in this chapter, which has a rubbery nature, but which can not be vulcanised in the conventional way with sulphur. This objection is taken away by copolymerisation with a small amount of isoprene. Butyl rubber has a very low resilience, but outrivals all other rubbers in resistance to gas permeation for that reason it is generally used for tyre inner tubes. 

Natural rubber, synthetic cw-1,4-poly(isoprene), butadiene rubbers, and styrene-butadiene rubbers are all sensitive to oxidation because of their high carbon-carbon double bond fractions. Attempts to reduce sensitivity to oxidation with maintenance of the vulcanizability have lead to the development of what are known as the butyl rubbers, IIR, which are copolymers of isobutylene with a little isoprene. But butyl rubbers only have a small rebound elasticity. However, since they also have poor gas permeability, they are mostly used for tire inner tubes. 

Subsequent recombination produces a secondary ozonide (or just ozonide). In small olefins, ozonide formation is generally a facile process. In stretched rubber, however, ozonide formation is more difficult, since the cleaved intermediates may be forcefully separated to relieve the stress. Interestingly, both crosslinking and chain scission products may form during rubber ozonation. Rubbers containing trisubstituted double bonds (e.g., polyisoprene, IR, and butyl rubber, IIR) are more prone to yield chain scission products. Several pathways can lead to chain scission. 

Table 4.7 Physical and Mechanical Properties of Butyl Rubber (IIR) ...

Particularly synergistic properties can be obtained using ternary polymer blends that cannot be achieved with binary blends. Ternary blends based on NR, BR and EPDM have been used for tyre sidewalls and show excellent ultimate properties, better ozone resistance and fatigue resistance under dynamic load. Spedlic morphology development, crosslinking behaviour and their correlation to mechanical properties of different ternary rubber blends like butyl rubber (IIR)/NR/SBR and NR/BR/SBR blends have been well... 

The miscibility of natural rubber (NR) blends is one of the most important factors when designing NR products. For instance, when the NR is miscible with a dissimilar polymer on a molecular level, we may improve the properties of NR as a function of the composition of the polymer. This is significantly different from the design for immiscible NR blends, whose properties are greatly dependent upon the morphology of the blend but less so on the composition. In most cases, NR is immiscible with non-polar synthetic rubbers, i.e. NR/butadiene rubber (BR) with high c -1,4-butadiene units, NR/styrene-butadiene rubber (SBR), NR/butyl rubber (IIR), NR/silicone rubber (q)13,i4 NR/ethylene-propylene-diene rubber (EPDM). This means it is important to find miscible NR blends and to control the morphology of the immiscible NR blends in a rational way. In this chapter, properties of NR blends are described from the viewpoint of miscibility, i.e. the miscible blend of NR/BR and the immiscible blend of NR/SBR. 

Butyl rubber (IIR) is made by copolymerising isobutylene with small amounts (typically 0-5-3 0 parts per hundred parts of isobutylene) of isoprene (Fig. 1). The reaction occurs through an ionic mechanism, by means of which isoprene enters chains of polyisobutylene at irregular intervals (averaging approximately 200-40 isobutylene units) whose... 

PP/EPDM-V Vulcanized EPDM dispersed in polypropylene PP/NBR-V Vulcanized nitrile rubber dispersed in polypropylene PP/IIR-V Vulcanized butyl rubber dispersed in polypropylene... 

PP/IIR-V, a dynamically vulcanized butyl rubber dispersed in a polypropylene... 

PP/IIR-V is marketed to compete with conventional butyl rubber thanks to its low gas permeability, compliance with the pharmacopoeia and, secondarily, its damping properties. 

PP/IIR-V is used in medical, industrial and consumer goods requiring low permeability to moisture, air and oxygen, competing with butyl rubber. 

Isobutylene is used to make butyl rubber (HR), which is mixed with polypropylene in a dynamic vulcanization process to produce a thermoplastic vulcanizate (PP/IIR) that is more resistant to air permeabiiity than other TPVs. 

ZDEC is used in the following applications as a fast primary or secondary vulcanization accelerator in NR, SBR, IIR, EPDM and for natural and synthetic latex a stabilizer in butyl, butadiene, and urethane rubbers an antioxidant in rubber-based adhesive systems a stabilizer in cement a heat stabilizer for polyethylene. 

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