OCAS Journal
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PLASTICS AND ITS EFFECTS ON Considering the magnitude of the ENVIRONMENT problem, the most logical sources would be somewhere along the supply chain of 1. Introduction: the plastics industry. Plastic is a toxic material that is severely affecting marine creatures and the marine ecosystems and ultimately humans. We only see the stuff that floats. But it can sink and or float depending on the environmental conditions of the ocean. Because the specific gravity of much of it is roughly that of the ocean water, it can rise in rough seas and sink during the calms. Sunlight, which has very limited penetration in the water, breaks it down into continuously smaller particles until The disposable plastic bottle it reaches molecular size. Some of the symbolizes waste and litter around the plastic debris has taken a fifty-year world. But it is not just plastic bottles voyage in violent seas since it was first and careless littering that threaten to produced. And it doesn’t appear to be turn the oceans from life sustaining to breaking down into something that is life threatening. Bottles and straws bags, even close to the natural materials of the discarded toys, product packaging and earth they once came from. There are cheap holiday decorations. Household estimates of how long this will take, but and industrial waste of a thousand it clearly takes more than fifty years. kinds. Littered, dropped, and dumped. According to a study published in 1992 Used despite safer alternatives, by the US Environmental Protection carelessly disposed, improperly Agency (EPA), plastic pellets were one managed. Not reduced, not reused and of the most abundant types of debris not recycled. Plastic in the oceans is found in US harbors of the Atlantic, entirely caused by human action and Pacific, and Gulf of Mexico. These human inaction. It has as much hurdles are the feed stock of the plastics potential to do harm as the worst industry and come in a variety of shapes climate change scenario and is having spherical, ovoid, and cylindrical — — greater immediate effects. with sizes ranging from one to five There are a number of ways that millimeters diameter. In 1992, nearly marine science, waste management, sixty billion pounds of these plastic recycling and materials experts, pellets were made annually in the biochemists and medical professionals United States and are shipped via train, might be brought together to work on truck, and ship. The most commonly the interrelated problems from a produced resins include polyethylene, number of critical angles. But currently, polypropylene, and polystyrene. there are no major collaborative efforts among these disciplines. If plastic in the and informal dump sites that are poorly ocean can be safely collected, existing located or lack proper controls. and new technologies can be used to Mega- and macro-plastics have reprocess and reuse it. Research can accumulated in the highest densities in determine the requirements, risks and the Northern Hemisphere, adjacent to potential for commercially viable urban centre’s, in enclosed seas and at operations that could turn this water convergences (fronts). Report environmental disaster into an economic reveals that, lower densities on remote opportunity for the right companies. island shores, on the continental shelf Less than 20 percent of leakage seabed and the lowest densities (but still originates from ocean-based sources like a documented presence) in the deep sea fisheries and fishing vessels. This means and Southern Ocean. The longevity of over 80 percent of ocean plastic comes plastic is estimated to be hundreds to from land-based sources; once plastic is thousands of years, but is likely to be far discarded, it is not well managed, and longer in deep sea and non-surface thus leaks into the ocean. Over half of polar environments. Plastic debris poses land-based plastic-waste leakage considerable threat by choking and originates in just five countries: China, starving wildlife, distributing non- Indonesia, the Philippines, Thailand, native and potentially harmful and Vietnam. These countries have all organisms, absorbing toxic chemicals succeeded at achieving significant and degrading to micro-plastics that growth in recent years, and they are at a may subsequently be ingested. Well- stage of economic growth in which established annual surveys on coasts consumer demand for safe and and at sea have shown that trends in disposable products is growing much mega- and macro-plastic accumulation more rapidly than local waste- rates are no longer uniformly increasing: management infrastructure. This creates rather stable, increasing and decreasing a dual problem: the scale of collection trends have all been reported. The and the retention of waste within the average size of plastic particles in the system itself. Our field research and environment seems to be decreasing, interviews with public officials have and the abundance and global also shown that these countries distribution of micro-plastic fragments acknowledge the problem and are have increased over the last few actively looking for collaborative decades. However, the environmental solutions. Of the leakage that comes consequences of such microscopic from land-based sources, we found that debris are still poorly understood. 75 percent comes from uncollected 2. What are Plastics? waste, while the remaining 25 percent Plastics are derived from leaks from within the waste- materials found in nature, such as management system itself. Post natural gas, oil, coal, minerals and collection leakage can be caused by plants. The very first plastics were made improper dumping, as well as formal by nature, rubber from a rubber tree is actually a plastic. Interest in making plastics arose in the 1800s to replace 4. Chemistry of Plastics scarce materials such as ivory and The chemistry of plastics can be tortoise shell. The first synthetic plastics complex, but the basics are were derived from cellulose, a substance straightforward. Think back to your found in plants and trees. Cellulose was high school science lessons about atoms heated with chemicals and resulted in a and molecules (groups of atoms). new material that was extremely Plastics are simply chains of like durable. The raw materials for today’s molecules linked together. These chains plastics come from many places (some are called polymers. This is why many even use salt!), but most plastics can be plastics begin with “poly,” such as made from the hydrocarbons that are polyethylene, polystyrene, and readily available in natural gas, oil and polypropylene. Polymers often are coal. made of carbon and hydrogen and sometimes oxygen, nitrogen, sulfur, 3. Types of Plastics chlorine, fluorine, phosphorous, or There are two types of silicon. plastics: thermoplastics and thermosetti The term “plastics” encompasses all ng polymers. Thermoplastics are the these various polymers. Although there plastics that do not undergo chemical are many polymers, plastics in general change in their composition when are lightweight with significant degrees heated and can be molded again and of strength. Plastics can be molded, again. Examples extruded, cast and blown into seemingly include polyethylene, polypropylene, po limitless shapes and films or foams or lystyrene and polyvinyl even drawn into fibers for textiles. Many chloride. Common thermoplastics range types of coatings, sealants and glues are from 20,000 to 500,000 amount, while actually plastics, too. thermosets are assumed to have infinite molecular weight. These chains are 4.1 Classification of Plastics based on made up of many repeating molecular Chemistry units, known as repeat units, derived Plastics are usually classified by from monomerseach polymer chain will their chemical structure of the polymer's have several thousand repeating units. backbone and side chains. Some Thermosets can melt and take shape important groups in these classifications once; after they have solidified, they are stay solid. In the thermosetting process, the acrylics, polyesters, silicones, polyur a chemical reaction occurs that is ethanes, and halogenated plastics. irreversible. The vulcanization of rubber Plastics can also be classified by the is a thermosetting process. Before chemical process used in their synthesis, heating with sulfur, the polyisoprene is such as condensation, polyaddition, and a tacky, slightly runny material, but cross-linking. after vulcanization the product is rigid and non-tacky. 4.2 Classifications based on Physical property 4.2.2. Natural vs synthetic Other classifications are based on Most plastics are produced qualities that are relevant for from petrochemicals. Motivated by the manufacturing or product design. finiteness of petrochemical reserves and Examples of such classes are the threat of global warming, bioplastics are thermoplastic and being developed. Bioplastics are made thermoset, elastomer, structural, biodeg substantially from renewable plant radable, and electrically conductive. materials such as cellulose and starch. In Plastics can also be classified by comparison to the global consumption various physical properties, such of all flexible packaging, estimated at as density, tensile strength, glass 12.3 million tonnes/year, estimates put transition temperature, and resistance to global production capacity at 327,000 various chemical products. tonnes/year for related bio-derived 4.2.1 Biodegradable plastic materials. Biodegradable plastics break 4.2.3. Crystalline vs amorphous down (degrade) upon exposure