Plastic, one of the most versatile materials (and why we must be very careful)

By using gas or oil as fuel, we not only pollute and contribute to global warming. We are wasting irreplaceable raw material for the most versatile material ever invented: plastic.

There are several types, so it is more accurate to speak of plastics in the plural. Not all derive from the processing of hydrocarbonsbut they do have some common features.

All the plastics they are synthetic: do not occur in nature and are the result of a manufacturing process. They are synthesized from other materials, through chemical processes that break down organic substances and recombine molecules of the same type to form chains that repeat and intertwine. The chains are known as polymers, and the chemical composition of the molecules that make up the polymer is what determines the characteristics of each plastic.

Raw materials

The other common characteristic that defines them is that they can be given the shape you want. The word ‘plastic‘ derives from the ancient Greek ‘plastikos’which means moldable or that can be shaped.

There are plastic substances in nature, flexible materials formed by molecular chains that an organism molds, such as the cellulose of trees, the sap of plants or the ligaments and cartilage of animals. However, we cannot use them as they are to reshape them, and only some of them can be used as raw material to synthesize usable plastics.

The first use and synthesis of plastics occurred in tropical regions of America. The oldest historically verifiable was in the Mayan culture, before the Spanish conquest. The Mayans used the resin or latex of the rubber tree to make objects, from figurines to shoes and elastic cord to build weapons of wood and stone, and the balls with which they played a ceremonial sport.

“Rubber was not used systematically in the West until Charles Goodyear discovered the process of vulcanization in 1839.”

Rubber was not used systematically in the West until Charles Goodyear (the tire brand) discovered in 1839 the process of vulcanization: a latex firing with a proportion of sulfur that returns to the plastic resulting much more rigid and durable. Sulfur alters the unions of the polymers, making their interlacing more compact and less flexible, but unlike pure latex, the shape it is given, on cooling, is irreversible.

Rubber began to be used as a lining for carriage wheels., until then made of wood or metal and of a very uncomfortable rigidity, which also damaged the structure of the vehicles with each pothole. The tires, first solid and eventually with an inner tube that made them inflatable and better cushioning for vehicles, were massively used on cars (which replaced carriages), trucks and even bicycles.

To ensure the supply of the raw material, the cultivation of rubber trees spread throughout the tropical zones of the world, including Africa, South America and Southeast Asia. World War I put the supply of rubber at riskaccelerating the search for alternatives that led to the synthesis of oil-based rubber.

Before, others were invented plastics rigid: bakelite, produced from phenol and formalin in 1907 by the Belgian Leo Baekeland. Although it was very rigid, expensive and dangerous to produce, it was a revolutionary invention that began to make plastic products available to the public.

great variety

The plastics They are classified according to the chemical structure of the chains of molecules that form them. They can be urethane chains, esters, vinyl, and other base substances, giving rise to their names.. We thus have polyesters (PE or PET), polyvinyl (PVC), polyurethane, etc..

Each type has particular characteristics, but there are two general groups defined by their malleability: thermoplastics and thermosets. They both have polymer chains as their base, but the difference is that thermoplastics do not change their chemical composition when heated, so you can reshape them multiple times by melting them.

Thermoplastics are relatively soft or flexible At room temperature, they melt in the heat and harden in the cold. They are the easiest to recycle, although eventually their qualities degrade or change if they are molded many times.

Thermosets can be molded only once, such as rubber vulcanization. Thermosets (thermohard) keep their shape. Some can be recycled, but under processes that change their composition or not necessarily for the same use.

multiple uses

The jump to the era of plastics It began with the massive industrial production of compounds obtained from the processing of vegetable cellulose, rubber and petroleum derivatives, accelerated after World War II.

This opened the doors to new plastics at low cost and for an infinity of uses. Unfortunately, this led to a ubiquity of disposable uses and waste, in many cases polluting and problematic for not being recyclable or biodegradable. It is estimated that, globally, 50 kilos of plastic are produced per person per year and, according to the UN (2021), less than 10% of the plastic produced so far has been recycled.

Today we are aware of the problem that the use of plastics is causing, and a wide variety of solutions have emerged. In the following pages we will deal with the variety of plastics and their environmental implications, including innovations that are allowing us to clean oceans and places plagued by plastic waste.