Scientists propose new systematization for polymers and nonpolymers

July 08, 2014

What are polymers? A better question is, What are biopolymers or bioplastics? Are these so-called bioplastics produced from plants grown upon the earth through industrial processes more bio-based than plastics produced from natural substances found beneath the earth's surface? Are all polymer materials and substances just polymers? Or do we need new definitions of polymers and a way to systematize the various polymer materials and substances?

Those are the questions that Professor D.Sc. Igor Catic (retired) and his colleagues Maja Rujnic-Sokele and Gordana Baric, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia, are pondering. The group decided it is time for a new paradigm for the systematization of substances and materials, and has published a paper in Vol. 9 of Rubber, Fibres, Plastics in January of this year.

What is natural technology vs. artificial technology? And when did artificial technology start? The group notes that "general technology starts with a natural one" and the "natural material technology starts" at the quantum level with "quarks and connected with gluons" resulting in the development of macromolecular components, which were formed into natural inorganic materials—minerals.

The paper notes, quoting Aristotle, that "there is a relationship between the form and the matter; the form being always the first . . . [which] precedes the creation of any level of matter. For example, the making of thermoset, rubber, and ceramic materials precedes primary shaping."

The question we need to ask is whether polymers are natural or synthetic. According to Dr. Catic and his colleagues, "the name polymers is an umbrella term for natural and synthetic substances and materials with the basic component being a system of macromolecules." Based on this, they have determined there are groups of macromolecular components; inorganic macromolecular compounds (inorganic polymers and inorganic nonpolymers); and organic macromolecular compounds (organic polymers and organic nonpolymers).

"The fact that we have only two groups of substances and materials—polymers and nonpolymers—led us to the idea to propose a new systematization of substances and materials," they write. Going back several billion years, to a period of "natural technologies such as geological processes of nonliving materials and biosynthesis," they follow the inorganic side of natural technologies: "natural inorganic polymers or natural geo-polymers," such as clay, mica, and zeolite.

Next are your basic organic polymers—"biopolymers with very complicated and complex forms and structures, are proteins, nucleic acids, and polysaccharides"—and from these "appeared the living organisms, followed by plants and animals. The death of living organisms resulted in the nonliving organic natural products: crude oil, natural gas, and coal. This means that fossil fuels are natural raw materials, pure products from nature." Natural processes turned these fossilized organic materials into other organic materials, all via natural processes and from nature itself.

Through industrialized processes developed very recently (just over 100 years ago), scientists have engineered ways to turn these natural fossilized organic materials into other materials through the use of heat and other reactive processes. "This is the case of reactive primary shaping, so often in the production of plastics (always for thermosets and in some cases for thermoplastics) and rubber parts," writes the group.

"Synthetic plastics and rubber can be made by different polymerization [processes] from natural sources: crude oil, natural gas or coal, or from planted products, corn or potatoes," they write in the paper, noting that the first synthetic plastic (phenol formaldehyde) was Baekelite in 1907.

So what about the term bioplastics? Catic and his colleagues write in their paper: "Bioplastics is not a new term, but they participate only with about 0.5% in overall production of plastics. However, a number of leading global companies impose bioplastics as an absolute hit, and a universal solution for all the world's problems, particularly for climate change."

Catic, Rujnic-Sokele, and Baric were pretty astounded by the "propaganda" they encountered surrounding bioplastics that occurred at the K fairs in Düsseldorf, Germany, in 2007 and 2010; so much so that it prompted the authors to respond. In fact, they came to the conclusion that "such propaganda that favours bioplastics as a form of plastic derived from renewable biomass sources, such as vegetable oil, corn starch, pea starch, or microbiota, can cause unforeseeable consequences for fossil plastics image and plastics in general," they write.

They also questioned the "ambiguity of converting food into plastics and especially into biofuel," and caused them to establish a "new criterion for the classification of plastics to the existing criteria . . ." There is little difference between so-called natural and synthetic polymers, the group notes. Whether the material is "grown matter from the living [plant], used in cellulose, for example, [b]y modifying cellulose we make, e.g., cellulose acetate (CA) . . ."

The group notes that "polyurethane (PU) and polyamide (PA) are products of castor oil. . . . The main characteristic of natural organic polymers is the forming by reactions of biopolymerization." In other words, an industrial process can take an organic material and create inorganic products like toothbrushes, car parts, and foam insulation. "Bioplastics are also man-made organic polymers and, thus, just one group of plastics, and at the moment with a very low share in the total production of plastics," they write. "Concerning the environmental impact, the criterion for division of plastics cannot be the origin of the input into the process, but only the footprint."

Catic and his colleagues quote researchers from the Royal Institute of Technology in Stockholm: "We have managed to prove that fossils from animals and plants are not necessary for crude oil and natural gas to be generated. The findings are revolutionary since this means on one hand that it will be much easier to find these sources of energy and on the other hand, that they can be found all over the globe."

So perhaps Jon Huntsman Sr.'s favorite saying doesn't really have any bearing on the plastics vs. paper debate: "Use old dinosaurs, not new trees." Perhaps, after all the wrangling is done, both can be called bioplastics.

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