There are many types of polymer degradation mechanisms: thermal, mechanical, photochemical, radiation chemical, biological and chemical degradation (Schnabel, 1981). According to ASTM definition, “degradable plastics are the plastics that are designed to undergo a significant change in its chemical structure under specific environmental conditions, resulting in a loss of some properties that may vary as measured by standard methods appropriate to the plastic and the application in a period of time that determines its classification”. This definition can be applied to many polymer degradation types including photodegradation, thermooxidation, hydrolysis and biodegradation. Autooxidation is the cause of thermooxidative degradation of organic materials without light. In natural photodegradation, sunlight reduces the molecular weight of the polymers by photooxidation and direct bond cleavage (Hand Book of Polymer Degradation, 2000). Another mode of degradation is hygrothermal degradation. Substantial loss of weight and mechanical properties of a material due to the effects of moisture and temperature is called hygrothermal degradation (Balakrishnan, Hassan, Imran, & Wahit, 2011). For instance, aged PLA/jute fiber composites in hygrothermal environment showed 15% decrease in tensile strength after 24 h …show more content…
The elongations-to-break of aged PHB and PHBV at 15°C decreased by 64% and 72%, respectively, after 168 days (Srubar et al., 2012). Ultimate strengths decreased by 28% and 8.9% for PHB and PHBV, respectively. During the aging process, the amorphous regions of PHB and PHBV underwent glassy aging in the rigid amorphous fraction, resulting a significant embrittlement. Over the testing period, PHB and PHBV samples had a maximum increase in modulus of 166% and 178%, and crystallinity of approximately 41% and 58%, respectively (Srubar et al.,
Have you ever wondered why the plastic bag that you left on the porch during winter cracks or breaks more easily than when you left it during summer time but a piece of wood which was left just like the plastic bag has no effect whatsoever? This is because of a phenomenon, which only happens to polymers, known as the glass transition. For each polymer, there is a certain temperature at which the amorphous polymers undergo a second order phase transition from a rubbery and viscous amorphous solid to a brittle and glassy amorphous solid called the glass transition temperature, Tg.1 When the polymer, or in this case, the plastic bag, is cooled below their glass transition temperature, it becomes hard and brittle like a glass but when it is used above their glass transition temperatures, it might have a different effect than when used at room temperature or below the glass transition temperature as normally, different types of polymers like clothes, food packaging, insulations for wires, etc. are either used above their glass transition temperatures or
Service life The effect of fillers on polymers is that they are very beneficial because they don’t get ruined for a long time. Glass fillers are the most commonly used fillers in polymers. This is because they last longer and their service life is longer.
National Center for Manufacturing Sciences. (2004, August 11). Environmental Roadmapping Initiative. Retrieved October 14, 2011, from Plastics Impacts, Risks and Regulations: http://ecm.ncms.org/ERI/new/IRRPlastics.htm
It is a thermoplastic which is in solid form in its normal temperature but when heated above the glass transition temperature it becomes into liquid and can be easily molding.
The food we consume everyday touches plastic infinitely, whether it is during the preparation stages, packaging, storage or even just eating the food from a plastic plate. There is no escaping the fact that the food we eat has a huge contact with plastics. However, what does this mean for our food? There is an adverse effect to plastics and their contact with foods, particularly acidic, fatty or salty foods. The chemicals in plastics go through a process called “leaching” or “migration” which leads to transfer of polymer additives, impurities and polymerisation solvents into packaged goods with a consequent risk of toxic hazard to the consumer (Crompton, T. (1979). [book]). In this
One of the main challenges that face the environment today is the threat of plastic materials in the environment. All forms and sizes of plastic are harmful to the environment; this paper looks at the effects of microplastics which are small forms of plastic that are at least 5mm in size. Due to their small size, the microplastics end up being ingested into the bodies of aquatic animals causing health consequences that are uncertain to the organisms. This review focuses on the susceptibility of marine organisms to the physical, chemical and biological uptake of microplastics.
A polymer is a large molecule that is known as an organic compound. Polymers are used in many different ways to form different structures but mostly polymers are used to create various kinds of plastics. A polymer is made from the covalent bonding of smaller repetitive molecules. As seen in figure 1. These repeating molecules are built into chains, and different polymers have varied chain lengths. These smaller molecules which make up the polymer are known as monomers. Through the reaction of polymerization which generally requires a catalyst polymers are formed. Various Polymers are built of different types of monomers, some contain only one type of monomer whereas others can contain up to two or more monomers. These polymers are known as natural polymers, they occur in nature and then are extracted for use. Natural polymers are often water based, examples are silk,
Tillman, Gerngoss U., and Slater C. Steven. "Making Packaging Greener – Biodegradable Plastics." Biodegradable Plastic News. 2 Aug. 2007 <"Background Press Information." Background Press Information. 28 July 2007 .>.
Sefidi 4 Yasaman Sefididiznab Professor Margaret Neff ENG-112-44 1 December 2017 Plastic Pollution Products made from plastic are a part of everyday life, and plastics of any kind make our lives easier, and seemingly better. We drink water and juice from plastic bottles, work on our laptop using plastic keyboards, plastic utensil, plastic toys, and plastic bags. Plastic is so cheap that tons of plastics are designed to use just one time. Plastic is made from refined oil, and mixed with poisonous chemicals and cooked at the high temperatures, making it resistant to the earth's traditional methods of decomposition. Plastic can be made in any shape, and color, also it is so strong, and it can carry heavy weights. According to the Environmental
Thermal properties of material (Tg, Tm, Td) are those properties that response to temperature. They can be studied by thermal analysis techniques including DSC, TGA, DTA and dielectric thermal analysis. The nanometer-sized of inorganic particles incorporated into the polymer matrix can improve thermal stability by acting as a superior thermal insulator and as a mass transport barrier to the volatile products generated during decomposition [117]. Khanna et al. [57] reported the thermal (TGA) analysis of the PVA/Ag nanocomposite. They observed that the decomposition profile starting at about 330 ◦C and continuing till about 430 ◦C. They also found the PVA/Ag nanocomposites have higher thermal stability than the PVA alone. Mbhele et al. [99] also observed that that the pure PVA starts decomposing at about 280 ◦C and
Synthetic plastics are used widely in food packaging, detergents, cosmetics, pharmaceuticals and other chemicals’ packaging. Almost 30% of the synthetic plastics are used for packaging applications in the world and this rate is expanding at 12% per annum. They have replaced traditionally used papers and cellulose products for packaging purposes because of owing better physical and chemical properties. Polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyurethane, poly(ethylene terephthalate), poly(butylene terephthalate) and nylon are most commonly used plastics. Plastics possess not only suitable thermal and mechanical properties but also better stability and durability. Plastics have attractive more public and media attention because of its durability and visibility in a litter as compared to other solid components. In 1993, total world consumption of this material was 107 million tons and it reached to 146 million tons in
Millions of plastic bags are given out to consumers by supermarkets and stores to carry their goods in. They are also cheap, light, durable, easy to carry and in many cases, free. The most commonly used shopping bag is made of High Density Polyethylene (HDPE). This type is used in the majority of supermarkets and stores. After these bags are used, they often end up in landfills or as litter, roughly only three percent of plastic bags is actually recycled per year (Planet Ark, 2011). The materials used in making plastic bags make them non-biodegradable. According to the science dictionary, 2011 refers to “these materials cannot be decomposed into environmentally safe waste materials by the action of soil bacteria.” These harmful substances are toxic and take approximately four hundred years to break down, or in this case photo-degrade; which is how plastics made from (HDPE) break down. Since they are not biodegradable, they remain in the environment and are absorbed in soil or water (Indian Centre for Plastics in the Environment, 2010). This essay will discuss the various harmful effects of plastic bags, and demonstrate the risks that these bags impose on humans, animals and the environment. It will also discuss a series of suggested solutions that could help reduce plastic bag usage.
Recycling is the process by which a waste material is converted again into reusable process and disposal is a process by which we get rid of something. Polymers are not very reactive so this property makes them very useable for storing food but this property makes it difficult to recycle or dispose of polymer. This difficulty in recycling and disposing of polymer is a major cause of environment hazard. Since the waste of polymer is increasing day by day so proper measurement should be taken to reduce the use of polymer and different method should be made to properly dispose and recycle waste. Following are the process by which a polymer is recycled or disposed.
Solid waste can be classified in different types, depending on their source, household waste is generally classified as municipal waste; industrial waste as hazardous waste or hospital waste as infections waste. It quite obvious that South Africa environment is deteriorated by the illegal dumping area that around here. Solid waste is a major problem this country is facing at the moment. The province that is experience this major problem is Gauteng province, this an urban area am taking about, and since it’s clear that over population is the cause of the problem. Gauteng province is an over populated than rural area .solid waste pollution is refuse or garbage that people use in their everyday life in their house, such as plastic
Millions of tons of plastics are disposed of into oceans and other water sources (i.e. rivers, ponds, etc.). The incorrectly discarded plastics are swept up by large ocean currents, and over time degrade into microscopic particles. These microparticles may be the cause of various adverse human and wildlife health effects, such as infertility and the inhibition of growth. This distressing issue must be brought further to the public’s opinion, and heavily regulated to reduce the effects.