Synthetic polyisoprene IR

However, in spite of these developments the market for the synthetic polymer has proved disappointing and many plants in the Western world have been mothballed . The greatest use appears to be in the one-time Soviet Union, where it was developed to avoid dependence on the natural material. 

Initial attempts to make synthetic rubber similar to NR date back to mid 1800s. Modern synthetic polyisoprene is designed to be similar to natural rubber in structure and properties. Although it has lower green strength, slower cure rates, lower hot tear, and 

The main reason that this rubber is not used in process industries in place of natural rubber could be that the price of this rubber is much more than that of natural rubber. 

290 Aliphatic Polyolefins other than Polyethylene, and Diene Rubbers 

---

The curing and dynamic properties of precipitated nano-silica on NR without and with the sulfur addition (NR with S), synthetic polyisoprene (IR), polybutadiene (BR) and SBR was investigated. Silica was treated with bis(3-triethoxysilylpropyl)tetrasulfane (TESPT) to form bonds at interfaces. Cure, Mooney viscosity, glass transition temperature, bound rubber, crosslink density and DMA were measured. The properties of silica-filled SBR and BR correlated with highest rolling resistance and SBR-silica correlated with best skid resistance. A Payne effect was observed in the loss modulus under some experimental conditions. In addition to possible filler de-agglomeration and network disruption, the nanoscale of the filler may have further contributed to the non-linear response typified by the Payne effect. ... 

NR is an important elastomeric material, used in around 70% of all tyres and in a variety of applications in the engineering, medical, sport and household sectors. This is due to its outstanding properties which cannot be matched by the synthetic polyisoprene (IR). Before the vulcanization process, NR is not... 

Vulkanox HS is an antioxidant with relatively weak staining and discoloration characteristics, it provides outstanding heat protection in natural rubber (MR), synthetic polyisoprene (IR), polybutadiene (BR), styrene butadiene rubber (SBR), nitrile rubber (NBR) and ethylene propylene rubber (EPIBl), but is less suited>le for polychloroprene (CR). Its performance is improved further in combination with Vulkanox MB-2 antioxidant, which is especially effective in thiuram cured articles with low levels or sulfur or without sulfur. Vulkanox HS antioxidant also yields good protection against rubber poisons. 

Synthetic Polyisoprene Rubbers (IR). IR is a cis-1,4 polyisoprene synthetic natural rubber. However, it does not contain the non-rubber substances that are present in NR. One can differentiate between two basic types of synthetic polyisoprene by the polymerization catalyst system used. They are commonly referred to as high cis and low cis types. The high cis grades contain approximately 96-97% cis-1,4 polyisoprene. 

The first patent on PAB was granted to Parkes in 1846 for two natural polymers co-vulcanized during blending in the presence of CS2, i.e., a natural rubber (NR = amorphous c/s-polyisoprene, IR) with gutta-percha (GP = semicrystalline trans-polyisoprene, IR). Thus, mbber PAB predates that of synthetic polymers by ca. 80 years (PMA/PVAc 1929). Notably, while the early plastics were bio-based, their usage fell to <5 wt% nowadays slowly recovering from the absolute dominance of synthetic, petroleum-based plastics. 

Synthetic polyisoprene, isoprene rubber (IR), was introduced in the 1950s as odorless rubber with virtually the same properties as natural rubber. Isoprene rubber product and processing properties are better than natural rubber in a number of characteristics. MW and MWD can be controlled for consistent performance and processing properties. 

Among the variety of synthetic rubbers, EPM and EPDM are particularly known for their excellent ozone resistance in comparison with natural rubber (cfs-l,4-polyisoprene) and its synthetic counterparts IR (isoprene rubber), SBR (styrene-butadiene rubber), and BR (butadiene rubber). Secondly, EPDM rubber can be extended with fillers and plasticizers to a very high level in comparison with the other elastomers mentioned, and still give good processability and properties in end articles. This leads to an attractive price/performance ratio for these poljmiers. 

SJ Bunce, HGM Edwards, AF Johnson, IR Lewis, PH Turner. Synthetic polyisoprenes studied by FT-Raman spectroscopy. Spectrochim Acta 49A 775-783, 1993. 

Polydiene Rubbers. Most important of these is natural rubber (NR). Additionally used are butadiene-styrene rubbers (SBR) and synthetic polyisoprene rubbers (IR). They have very high molecular masses (several 10 to some 10 g/mol) and low Tg (- 70 to -40 °C). 

Synthetic polyisoprene rubber Synthetic natural rubber SN IR... 

Steinbuchel and co-workers, using rubbers as the sole source of carbon, found that NR and IR (synthetic polyisoprene rubber) biodegrade at a similar rate in the presence of Pseudomonas aeruginosa. NR gloves were 26% mineralised in 6 week compared with 21% for IR gloves. This slight difference may well have been due to the difference in the antioxidants used in the formulation, although these were not identified. It is clear, however that, contrary to the views of some environmentalists, there is no intrinsic difference between natural and synthetic polymers. 

---