This field of engineering is generally engineering which designs, analyses, or modifies polymer materials. Polymer engineering focuses on aspects of the petrochemical industry, polymerization, characterization, and structure of polymers, properties of polymers, compounding, and processing of polymers and description of major polymers, applications, and structure-property relations.
Materials worked upon in Polymer Engineering
Polymers are basically categorized into elastomers, thermoplastics, and thermosets. This categorization helps define their areas of application in a better way. The latter group of materials includes phenolic resins, polyesters, and epoxy resins, all of which are applicable in composite materials on reinforcing with stiff fibers like fiberglass and aramids. Since crosslinking leads to stabilizing the thermoset polymer matrix of these materials, they have physical properties which are more similar to traditional engineering materials like steel. However, they have very much lower densities which are compared with metal. They make them ideal for lightweight structures. In addition, they suffer less from fatigue, so are considered ideal for safety-critical parts which are stressed in service regularly.
With relatively low tensile moduli, elastomers have lower densities and properties like transparency which make them ideal for consumer products and medical products. They include polypropylene, polyethylene, nylon, polycarbonate, acetal resin, and PET, all of which are widely used materials.
Elastomers are polymers with very low moduli and which show reversible extension when strained, a valuable property for vibration absorption and damping. They may either be thermoplastic or crosslinked, as in most conventional rubber products like tires. Typical rubbers used conventionally include natural rubber, nitrile rubber, polychloroprene, polybutadiene, styrene-butadiene, and fluorinated rubbers.
Applications of Polymer Engineering
The typical applications of composites are monocoque structures which are used in aerospace and automobiles, as well as more mundane products like fishing rods and bicycles. The first all-composite aircraft was the stealth bomber, but many passenger aircraft such as the Airbus and the Boeing 787 utilize a rising proportion of composites in their fuselages, like hydrophobic melamine foam. The quite different physical properties of composites provide designers much higher freedom in shaping parts, which is why composite products often look different to conventional products. On the other hand, certain products like drive shafts, helicopter rotor blades, and propellers look identical to metal precursors owing to the basic functional requirements of such components.
Plastic is also a polymeric material which is in a semi-liquid state and has the property of plasticity and exhibiting flow. This engineering encompasses plastics material and plastic machinery. The nature of such materials poses unique challenges to an engineer. Mechanical properties of plastics are often difficult to quantify, and designing them meets certain specifications while keeping costs to a minimum. Other properties that the engineer has to address include outdoor weatherability, thermal properties like upper use temperature, electrical properties, barrier properties, and resistance to chemical attack.
Like in most engineering disciplines, the economics of a product plays an important role in this field of engineering as well. The cost of plastic materials varies from the cheapest commodity plastics which are used in mass-produced consumer products to the very expensive which are called specialty plastics. The cost of a plastic product is measured in different ways, and the absolute cost of plastic material is difficult to determine. Cost is often measured in price per pound of the material or price per unit volume of the material. In many cases, it is important for a product to meet some specifications, and cost could then be examined in price per unit of property.
Polymer science comprises three main sub-disciplines:
Polymer chemistry: It is a sub-discipline of chemistry which focuses on the chemical synthesis, structure, physical and chemical properties of polymers and macromolecules. The principles and methods used for polymer chemistry are common to the sub-disciplines of organic chemistry, physical chemistry, and analytical chemistry. Various materials have polymeric structures, from fully inorganic metals and ceramics to DNA and other biological molecules. However, this sub-discipline is typically referred to in the context of synthetic and organic compositions. Synthetic polymers are omnipresent in commercial materials and products which are used every day are referred to as rubbers, plastics, and composites.
Polymer physics: This is the field of physics which studies polymers, their mechanical properties, fluctuations as well as the kinetics of reactions which involve degradation and polymerization of polymers and monomers respectively. While it focuses on the perspective of condensed matter physics, polymer physics is fundamentally a branch of statistical physics. Polymer physics and polymer chemistry are also related to the field of polymer science, where this field is considered the applicative part of polymers. Being large molecules, polymers are very complicated for solving by using a deterministic method. Yet, statistical approaches can come up with results and are often pertinent, since large polymers are explainable efficiently in the thermodynamic limit of infinitely many monomers. Thermal fluctuations continuously affect the polymers shape in liquid solutions, and modeling their effect needs the use of principles from statistical mechanics and dynamics.
Polymer characterization: It is the analytical branch of polymer science. This discipline is linked with the characterization of polymeric materials on a wide range of levels. The characterization typically has as a goal for improving the performance of the material. Various characterization techniques should ideally be related to the desirable properties of the material like strength, impermeability, optical properties, thermal stability. The techniques of characterization are typically applicable for determining molecular structure, molecular mass, morphology, thermal properties, and mechanical properties.
Polymer engineers focus on the realm of developing or testing plastics or related equipment and processes. A bachelor's degree in this field is necessary for getting employment. Polymer engineers develop new polymers, manage a lab, handle projects and processes, and design equipment. They work primarily in the field of plastics development. They also help develop new plastics or help in the testing and evaluation of products. They are also expected to maintain a laboratory or oversee other employees in working on a product or process. They need a bachelor's degree in polymer engineering or a related subject, and they may need a state license.
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By: Preeti Narula
Posted By - Assistant Editor