Synthetic rubber and the need for sustainability

Synthetic rubber refers to any artificial rubber synthesized from monomers derived from petroleum by-products or those of natural origin. The former however made-up bulk of the synthetic rubbers that are in use today. Since the first successful synthesis of synthetic polyisoprene in 1887, there were many variations of synthetic rubbers developed throughout history. The brief timeline of the development of synthetic rubbers is shown in Fig. 1. Until today, there are more than 20 types of synthetic rubbers that are widely available in the market. Fig. 2 shows the data on demand and distribution of synthetic rubber by application in the year 2020, while a summary of the industrial production methods and properties of some commonly used synthetic rubbers is given in Table 1. Synthetic rubbers not only share many similar applications as natural rubber, but also provide an extended range of applications. The primary cause is that synthetic rubber is made using a wide range of monomers, resulting in a variety of rubber properties to be engineered, as opposed to natural rubber, which typically has just one chemical structure. For example, NBR has excellent oil resistance contributed by the polar nitrile group from acrylonitrile moiety in the rubber. The mechanical properties, oil, and chemical resistance of the rubber could be altered by manipulating the ratio of butadiene to acrylonitrile repeating units. Over the decades, the oils and gas industry has optimized the extraction and processing of crude oil and natural gas, resulting in the availability of cost-effective raw materials for synthetic rubbers. This is presumably one of the reasons to most of the synthetic rubber formulations and processing technologies used in the rubber industries today are still largely similar to those that were developed in the early days of synthetic rubber discovery.

	Fig. 1 Timeline of the development of different synthetic rubbers.

	Fig. 2 Demand for synthetic rubber in 2020 according to rubber types, and their respective applications.

Table 1 General description, properties, and applications of conventional synthetic rubbers