Polymers in Modern Life - Essay Example

?Polymers Polymer is a Greek word with the first part ‘poly’ meaning many while ‘mer’ meaning part. A polymer is therefore a substance with many parts. Polymers are a large molecule built by many repetitions of smaller parts. The parts are held by simple chemicals units which form a covalent bond. In most cases the repetition is linear and a chain is built up from its links while others the chains are branched or interlinked to form a three dimensional networks (Sinha, 2004, p3). Types of polymers The two main types of polymers are thermoplastic and thermosetting polymers. Thermosetting polymers the chains become cross-linked so that the solid materials are produced that can not be softened and that ca not flow. Polymers are usually made in one of two polymerization process. In condensation-polymerization the linking of molecules creates a by product, which is usually water nitrogen or hydrogen gas. Thermoplastic polymers consist of a series of long-chain polymerized molecules in which all the chains are separate and can slide over one another. Thermoplastic polymers The long chains of thermoplastic polymer are connected by weak forces alongside the chemical bonds extremely strong. When they are heated the walls weaken and the polymer becomes soft and flexible at a high temperature and becomes a viscous melt. The cycle can be reversed by cooling of the materials. Thermoplastic elements usually can be of semi-crystalline structure or amorphous structure. Civil engineering materials such as polyester, nylon 66 and polycarbonate are the best examples of amorphous thermoplastic polymers. The developments polymers technology has led to high performing types of polymers such as polythersulphone which is amorphous in nature and polyetheretherketone which are semi crystal-line. The above two are more efficient than the normal thermoplastic, although they are not employed in civil engineering due to high costs. Thermosetting polymers They can be used in two separate ways firstly as a composite that is when combined with fibrous materials and secondly when as an adhesive and maybe as epoxies. They are formed in two stage chemical reaction when a polymer such as polyster, vinylester or epoxy is reacted with a curing agent. The reaction can be performed in a normal room temperature or the application of either controlled heat or pressure. Thermosetting polymers are strong in nature and can be affected by heat. The two procedures used to polymerize the thermosetting polymers used in civil engineering are the cold system that are cured at ambient temperatures and the hot cure system whereby polymerization is performed at elevated temperatures. Polymer science The research on polymer science continues to come up producing new products in the market. The polymer science and engineering are marching together although they are more interested on new materials being produced. Poly was scientifically born to understand how rubber and plastic works and they can not be separated. Polymers are now forming the basis of clothing and automobiles among others. New elastomeric, plastics, adhesives, coatings and fibers among others are being invented by the use of new technology in science. The scientific theory accepts the relationship between polymer structure, physical property and their behavior. Polymers are playing a very important role in processing of other industrial products. Anisotropy in thermoplastic polymers plays a significant role in thermal conductivity. Highly drawn semi-crystalline polymer samples can have a much higher thermal conductivity as a result of orientation of the polymer chains in the direction of draw. For amorphous polymers, the increase in thermal conductivity in the direction of the draw is usually not higher than two. Many polymers experiment a viscous reaction as an elastic response towards stress and strain. Combinations of some elastic and various viscous elements are being used to determine the melting behavior of polymers. The above characteristics make them be classified under the viscoelastic material (Osswald, 2003, p81). Polymer in modern life There is the polyethylene terephthalate and their examples are the two liter beverage bottle. High density polyethylenes are the milk jugs and some bottles. The polyvinyl consist of plastic drain pipe shower curtains and some water bottles. The low density polyethylene is the plastic bags and most of garment bags among others. The polypropylenes have the bottle cups, the modern candy wrapper and are used to make the bottoms of some bottles. The polystyrene are very hard in nature and are mostly used in making the hard cups, eating utensils due to their ability to withstand high temperatures. They are sometimes used to manufacture food containers and popcorn packages. There are many types of polymer which have applications when they are in the powder form. The very fundamental example is that of paint additives as well as coatings. Polystyrene beads are essential for industrial packaging materials. Polymers being the chemical organic substances are fundamentally used in various manufacturing industries. They are commonly used as raw materials in plastic manufacturing industries. However, in plastic fabrications, polymers play a fundamental role in the manufacturing process. All plastics that are seen all over are just polymers that have been basically compacted in to various and refurbished into various shapes by undergoing a series of molding processes. Polymers are very important in the fiber glass manufacturing industries for they are facilitating the bonding process in glass formation. The molding process involves the viscous flow of liquid substances followed by a strategic solidification of the molten substance as suggested by (Chenier p291). However, the uses of plastics  in medical devices and packaging continues to grow and result to a significant benefit to patients, health care providers and those who foot the bill for healthcare costs. In relation to that, the functional and other requirements for polymeric materials in medical applications are becoming more demanding as well as better defined. Some of the commonly used polymers in the medical field comprise of: polyvinyl chloride (PVC), polyethylene (PE), polystyrene (PE), and finally polypropylene (PP) among others. PVC as a polymer materials in medical field are commonly used in numerous medical products. They are used in the manufacture of plastic containers for storage of solution. They are more applicable in this case because they withstand the temperature of the solution as well as resistant to reaction activities of the container. PVC plasticized with diethylehexylphthalate (DEHP) are commonly used in the manufacture of plastics that hold intravenous IV sets as well as blood bags in hospitals and medical centers. However, some polymers like the metallocene polyolefin are basically useful to deposit flexible vinyl in medical field because they don't easily react with chemicals due to their non-absorbance characteristic of drugs (Tang, Lambert and Rodgers 2001, p11). When working with polymers both medical and industrial manufacturing field, they may a times fail to perform due to various physical and chemical properties they posses. Failure in performance of polymers may arise due to high values of viscosity of molten polymerized compounds; the non-Newtonian nature of viscosity as well as temperature dependency may affect its performance. When this failure occurs it results to difficulties in the controlling of atomization thus being accomplished prematurely that is; before solidification process. However, low melting point polymers like the polyethylene is considered being the most easily atomized polymer, and powders with varied mass median diameter that is not more than 100 microns thus readily achievable whenever atomization is done. The low point effect has become a challenge in facilitating the atomization process thus becoming ineffective compared to the powder form production. There are various ways of testing and improving the polymers, these methods comprise of: the instrumental free falling dart test and the instrumental notched charpy impact test, the two methods can be linked to conventional determination of parameters to give a quality assurance nature of the polymers. The polymers contracting nature can be improved through evaluation of the polymer's behavior. This is important because it prevents the fracturing effect of the containers made of polymers. Together with technological advances especially the computerized system, it has been noted that rapid progress in coming up with various inventions is being made basically on stimulating the mechanics fracture testing by the use of numerical methods. Among these numerical methods are: the finite element method (FEM) and the finite difference method (FDM). These methods are essential whenever used because they result to the potential of optimizing experimental conditions important for improving as well as standardizing the evaluation methods. Finally the most important method used in determining the tensile characteristic of polymers is the use of converging flow method whereby, the extensional flow behavior is determined and evaluated from the behavior of then melt in a contraction flow region. The data created as a result of this test is important in the development process of resistant polymers as well as selection of the essential materials used thus improving the process of atomization in the development of polymerized equipments both industrial level as well as manufacturing enterprises and medical field. UHMWPE Polymers refers to polyethylene which has ultra-high molecule weight and it should be in a position to exhibit physical and mechanical properties. The most significant expressed characteristics that are visible involve the inert characteristic nature on chemicals, resistance and lubricity impact, and finally the abrasion impact just to mention but a few. UHMWPE emanates from a class of polymers that shows deceptively simple chemical compositions that comprise a combination of both carbon ad hydrogen molecules that enable them to have the malleability traits. Its simplicity in the structural design it gives a bigger complex hierarchy of organization structure to the molecule as well as sub molecular varied scales of measurements. However, the UHMWPE polymer is important because at molecular level, usually there is a possibility of the carbon base of the polyethylene to twist, fold, and rotate in different directions thus easier to work with when shaping in different structures of the ordered crystalline levels thus becoming of great benefit to the users as proposed by Kurtz (2009, p1). List of References Chenier J. P. (2002). Survey of industrial chemistry. New York, NY: Springer Kurtz S. M (2009). UHMWPE Biomaterials Handbook: Ultra High Molecular Weight Polyethylene in Total Joint Replacement and Medical Devices. Academic Press Lambert B.J, Tang F.W & Rodgers J.W. (2001). Polymers in medical applications. London, UK:  iSmithers Rapra Publishing  Osswald, T. A. Menges, G (2003).Materials Science of Polymers for Engineers. Cincinnati, Ohio: Hanser Verlag. Print. Sinha, R. (2004).Outlines Of Polymer Technology: Manufacturer Of Polymer. New Delhi: PHL Learning. Print. Read More