I. ABSTRACT
Polymers are made from relatively small molecular fragments known as monomers that are joined together. Synthetic polymers which include the large group known as plastics are divided into three groups: commodity thermoplastic, engineering thermoplastics (ETP), and advanced engineering thermoplastics (AETP). The engineering thermoplastics (ETP) have heat resistance, strong mechanical properties, lightness, self-lubrication, and easy manufacturing. This plastic category has been lately used to replace wood and metal applications.
To have a better understanding of ETP, we will discuss about outstanding properties of some well-known engineering thermoplastics materials which are polyamides 12 (PA12), and polyether ether ketone (PEEK) in aerospace industry. Also, we will focus on major methods to enhance performance of engineering thermoplastics by modification via specialty additives. II. INTRODUCTION
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Synthetic polymers which include the large group known as plastics are divided into three groups: commodity thermoplastic, engineering thermoplastics (ETP), and advanced engineering thermoplastics (AETP). In recent years, the whole new generations of the engineering thermoplastics (ETP) have become commercially available. These offer properties far superior, particularly in regard to high temperature performance, excellent heat resistance, strong mechanical properties, lightness, self-lubrication, and easy manufacturing. This plastic category has been lately used to replace wood and metal applications and open the door to new types of application for
It was found that ATH can help to improve the flammability of HDPE composites in decreasing of heat release rate, total heat release and mass loss rate. With addition of inorganic flame retardants including RP and EG, the ATH flame retarded HDPE composites show obvious synergistic effects in improving the flame retardancy [72].
The most common form of polyethylene is petroleum based or olefins based; as before mentioned polyethylene compounds have a wide commercial applicability and are made from non-renewable resources (Harding, Dennis, von Blottnitz, Harrison, & S.T.L., 2007). Its manufacturing processes are regarded as energy intensive and release significant amount of CO2 and heat into the atmosphere (Broderick, 2008). Next a little more detailed description of polyethylene’s production processes will be presented, with a focus on the way the material inputs are extracted and synthesized.
The Crystallinity of Kevlar Polymer strands, contributes to the unique strength and stiffness of the material. Kevlar is very similar to other common synthetic polymers, including Nylon, Teflon and Lycra. In all Polated to strength. Aromatic refers to the Carbon atoms attached in a ring, and Amides refers to a group of Carbon, Nitrogen and Hydrogen atoms. Kevlar fiber is therefore a “Polyaromatic amide”, as it has a high breaking strength.
Kailas, Prof. Satish V. Material Science. Indian Institute of Science, Chapter 11. Applications and Processing of Polymers.
Plastic fasteners have grown to become viable products for joining applications in various industries. They are regarded as suitable alternatives to metal fasteners, and are known for their flexibility, durability, and application versatility. The various material features and benefits makes them ideal products for applications in a variety of industries such as aviation, marine, automotive, construction, oil and gas, food and beverage, sewage plants, and heavy machinery.
Polyethylene (PE) is one of the most commonly used polymers which can be identified into two plastic identification codes: 2 for high-density polyethylene (HDPE) and 4 for low density polyethylene (LDPE). Polyethylene is sometimes called polyethene or polythene and is produced by an addition polymerisation reaction. The chemical formula for polyethylene is –(CH2-CH2)n– for both HDPE and LDPE. The formation of the polyethylene chain is created with the monomer ethylene (CH2=CH2).
Thermoset polymers contain no set arrangement of chains and as such they can be classified as amorphous i.e. they contain no distinct crystalline structure [3]. Thermoset materials are formed from a chemical reaction of a resin and a hardener or catalyst and this reaction is irreversible and produces a hard and infusible material [4]. Cured thermosets will not become liquid again if heated but above a certain temperature their mechanical properties can change substantially. The temperature at which this change can occur is called the Glass Transition Temperature (Tg) and it varies depending on the particular resin and hardener/catalyst used as well as its degree of cure and whether it was mixed properly. If the temperature of a thermoset material is raised above the Tg, the molecular structure changes from that of a hard crystalline polymer to a more flexible amorphous polymer. At this elevated temperature the properties of the thermoset such as resin modulus (stiffness) drop significantly and as a result the compressive and shear strength of the composite will do the same. Other properties such as water resistance and colour stability also reduce above the resin’s Tg This change can be reversed by cooling the material back down to below the Tg.
Polymer-Polyethylene is partially crystalline as well as amorphous because it has crystalline and amorphous regions. Also it has linear chains so this is the simplest structure compared to a branched or network chain. This can be of an advantage to it over other types of materials as its good toughness and elongation makes it very significant in the engineering industry as it can be moulded or extruded into shape...
German Chemist Hans von Pechmann first synthesized Polyethylene by accident in 1898 by heating diazomethane. His colleagues characterized the waxy substance polyethylene due to the fact that they recognized that it consisted of long ethene chains. It was then first industrially synthesized by accident in 1933 by applying extremely high pressure to ethylene and benzaldehyde. Over the years, development of polyethylene has increased due to the additions of catalyst. This makes ethylene polymerization possible at lower temperatures and pressures.1
Polypropylene is one of those most versatile polymers available with applications, both as a plastic and as a fiber, in virtually all of the plastics end-use markets.[3]
Cryogenics comes from the combination of two different Greek words, namely “kryos”, which means very cold or freezing and “genes” means to produce. Cryogenics is thus defined as the branch of physics and engineering which deals with the study of very low temperature (below 123K), their production and the materials behavior at such low temperature.
The above statement was taken from Laura McRoberts’ article named as “The personal and political implications of Machiavelli’s The Prince”. The article or research paper talks about the advises of Machiavelli given to Prince in order to rule a smooth Princedom. All the motivations given in the book was merely about political implications. But there are certain elements that also talk about personal implications in sense of it is for an individual too. not only for Kingdom or how to rule but also for the opportunities place before each individual.
Thermoplastics are the most commonly used raw materials for SLS process. Based on the applications, the raw materials can be selected based on the criteria’s related to mechanical properties, thermal properties, Electrical properties and manufacturing feasibility.
Everyone has heard a cashier one time or another mumble, “Paper or plastic?” as he put their groceries in a bag, but do shoppers know the effects of each vessel in which they carry their comestibles? There are many issues and benefits to both paper and plastic. The making and recycling of both paper and plastic bags can harm the environment. One must also look at the costs of making each bag. The convenience of each is also something to look at. Many people jump to conclusion that paper bags are better for the environment without knowing the facts. Since plastic bags are preferred by customers and plastic bags actually do not hurt the environment as much as paper ones do, consumers should feel at ease when choosing plastic.
But plastic is an extraordinary innovation that replaces many other expensive products with lightweight, strong easy to maintain , longer lasting material with a less expensive plastic. “Plastics are manufactured materials that can be shaped into almost any form.” Most plastics are made when two or more chemical compounds combine and cause chemical reactions to polymerize, or form a long chain of molecules to form. This causes the plastic to form. The plastic is then heated into a molten liquid and then molded into the shape needed. There are two basic types of plastics. They are thermosetting plastics and thermoplastics. The type of plastic it is determined by the way they react when heated. Thermoplastics are plastics that can be heated and melted and still reform its shape. Thermosetting plastics are just the opposite. They can be melted and cannot be reshaped into its original