Using polymer plasticizers: Is it possible?

Rubber and plastics have become an integral part of modern life, without which humans cannot live. These materials are used in shoe soles, garden chairs, all types of films, DVDs, CDs, tubes, hoses, tires, packaging, and a host of many other products.

Plasticizers are unique types of additives.

For instance, without plasticizers, PVC would have been extremely fragile and brittle, and would not have conquered the huge market as seen today. Without plasticizers, a majority of the injection molding compounds would have been completely unfit for that purpose, and certain blends of rubber would not have been produced at all.

Plasticizers make plastics elastic, extensible, flexible, and plastic at low temperatures. In a majority of the cases, polymer products can be produced only on a commercial basis by integrating a plasticizer.

As a matter of fact, the invention of plasticizers was mainly responsible for the development of the plastics industry. If it were not for this, the industry may not have developed much beyond the stage it was in the earlier days. This is because the first plastics, as well as modified natural polymers like Galalith or nitrocellulose, were brittle and hard, and hence they could not be used for daily applications.

Most certainly, it does not exactly increase the marketability of a novel material, if, for instance, people have to look after their combs as if they were made of Meissen porcelain.

The rubber industry also used plasticizers to refine its products

Extensive kneading makes unvulcanized rubber as soft as chewing gum because the kneading process breaks down the polymer’s long-chain molecules. But this means that other major characteristics of this useful material are also lost.

Due to this reason, rubber investigators made an early start by combining all types of liquid components into their black formulations—oils, pitch, coal tar, paraffin, terpenes (like camphor), and even Vaseline. This meant that the mixture of crude rubber was sufficiently sticky for various solid ingredients even when the size of the rubber molecules is not reduced considerably. Carbon black is an example of a solid ingredient that can be effortlessly kneaded together in the mixer.

These factors demonstrate the importance of these unobtrusive plasticizers with respect to polymer processing—and how they can completely transform the characteristics of what was originally a relatively unappealing polymer material. Paradoxically, this extraordinary power also demonstrates the fact that even eminent chemical historians are currently finding it difficult to acquire information regarding plasticizer technology.

The “right” plasticizers are significant to such an extent, that information gathered about the performance of plastic over the years has vanished into the vaults of firms utilizing polymers. As time passed, this meant that plasticizers became relatively anonymous utilitarian substances.

One Problem—Many Solutions

Over the years, the plastics sector’s order book for plasticizers has developed into an unorganized agglomeration of chemicals. However, it is governed by several “major families” of products.

Phthalates are employed in PVC films and cables, cellulose adhesives, and coatings. With dicarbonates, flexible PVC becomes elastic at low temperatures. Phosphates are utilized both as a hydraulic fluid and as a flame-retardant. Fatty acid esters—the distant relatives of margarine—are used for plasticizing rubber and vinyl resin floor coverings. For some applications, plastics technologists also turn to esters of tartaric acid and citric acid.

Growth and Development of Industry

The plasticizer sector is largely involved with conventional products. While it is quite unusual to devote so much effort to product development, it definitely pays off.

Over the past two years, the plastics market achieved a growth of just 4%, but despite this fact, the sales of certain specialist plasticizers increased by about 15%, in the same period. This figure alone is sufficient to show that the last chapter in the long history of plasticizers has not been written yet: innovative plastics and the latest demands placed on the products that are constantly made from them need novel solutions. Here, only the collective brainpower of plastics experts can do justice to these.

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