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properties of polymers essay
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Polymers are made of large molecules that consist of a many monomers fused together through chemical bonds to make a strong material. Certain polymers are made of different chemical compositions of different molecular weights, crystallization, different degrees of hydrophobic characteristics, and heating transformations. Polymer materials are utilized for their slow degradable capabilities, ability to influence new formation of bone tissue, and contain porosity for cells to latch onto and utilize. The drawback of using polymeric materials in implants is that the properties of the material are unable to support a sufficient amount of mechanical load that is required. A disadvantage to using polymeric material is that during the process of sterilization it can easily change the properties of the material. Some polymers such as Polymethylmethacrylate (PMMA) can be toxic to the body causing heat damages to tissue cells. PMMA may not generally be degradable in the body but release particles known as debris that can lead to inflammation to the surrounding tissue of the implant. PLGAs are known for not causing inflammation to the bone tissue and are highly biocompatible. These polymers induce production of osteoblast in surrounding bone tissue of the implant. (Dorozhkin, 2009) (6)
A polymeric material that is used for prosthesis is D, L-polylactic-polyglycolic acid (PLGA)/L-polylactic acid (L-PLA). This polymeric material is a copolymer that is comprised of three fourths of polylactic acid and one fourth of polyglycolic acid. Another type of PGLA copolymer is made of thirty percent of polyglycolic acid and seventy percent of polylactic acid. Poly lactic acid (PLA) is a polymer that is thermoplastic that has an amorphous structure. L(-)-...
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...catalyst of an inert material roughly around 200˚C under minimal pressure. In order to produce high density polyethylene, propene it is placed into solvent that is inert such as heptane. Heptane contains a compound of trialkyl alumina and titanium. (answers.com) (:( sorry) (12) The resultant is a mixture of both istactic and atactic material. The physical property of PP utilizes young’s modulus as it may vary. Rubber particles are incorporated into PP to give it the characteristics of stiffness and elasticity. PP are more favored than other plastics due to its rigidity and low costs for production. The melting point for this material is 160˚C, which is higher than other plastics. Being that PP has a high melting point it makes it more heat resistant.
Works Cited
(Castleman, 1976), (Kapanen, 2002), (Henton, 2005), (Dorozhkin, 2009), (Wahl, 2006), answers.com
Alumina and zirconia ceramics have been widely used in orthopaedic hip replacements for the past 30 years. The advantage of using these was lower wear rates than those observed using polymers and metals. Because of the ionic bonds and chemical stability of ceramics, they are relatively biocompatible and therefore more preferable to use than metals and polymers. Alumina is most commonly used as a femoral head component instead of a metal in a hip prosthesis because this would reduce the polyethylene wear that is generated. Alumina is a desirable biomaterial to use in hard tissue implants because of characteristics like excellent wear resistance, high hardness, bio inert, low abrasion rate and good frictional behaviour. Furthermore, it has excellent surface finish as well as high fatigue streng...
Prosthetics (pronounced prahs-THEH-tiks) is the branch of medicine that deals with the artificial replacement of a missing body part. A prosthesis (pronounced prahs-THEE-sis) is the general term for the artificial part itself that replaces the body part usually lost to disease or injury. Prosthetics has a long history, and recent design advances that use battery power and new lightweight composite materials are making prostheses better and easier to use.
The future for the total artificial heart with respect to using polyurethanes comes in the form of thermoplastic polyurethane (TPU), also known as polyurethane elastomers that have molecular structures similar to that of human proteins. TPUs have slower protein absorption (protein absorption is the beginning of the blood clotting process) this makes TPUs ideal candidates in the manufacturing of the total artificial heart because it provides more adhesive strength and mimics certain elements within the body. Hence, biomedical polyurethanes can lead the way to eliminate some acute health challenges that the total artificial heart currently faces. By virtue of their range of properties, polyurethanes and their new applications will continue to play an important role in the future of the total artificial heart.
These kinds of polymers have both some advantages and disadvantages. Although they are bioactive and biodegradable and provide high comppressive strength, Degradation of such polymers leads to undesired tissue response due to producing acid formation in degradation process. Metallic scaffolds are another method for bone repair and regenaration. They provide high compressive strength and enormous permanent strength. Metallic scaffolds are mainly made of titanium and talium metals. The main disadvantages of metallic scaffolds are not biodegradable and also discharge metal ions. Recent studies in metallic scaffolds mainly focus on biodegradable materials which can be used improve bioactivity of metals such as titanium.
The plastic obtained from polyethylene can be pressed into varying shapes, ranging from the simplest to the most complicated. The ethylene market is indirectly driven by the increased polyethylene consumption for the production of several plastic components. In 2011, the global propylene market is valued at more than $ 90 billion and significant growth is anticipated in the coming years. Acrylic fibers and coatings, PVC plasticizers and coatings, polyurethane resins, epoxy resins and propylene polymers are applied on polycarbonates and solvents, that are used in the production of propylene. The automotive industry is the biggest end-user of polypropylene. The enormous expansion of ethylene and propylene production will contribute to the growth of the ethylene and propylene market, along with the rising demand for downstream products from India, China, and the Middle East. Tight environmental regulations, fluctuations in raw material prices and political uncertainties in crude oil producing regions are the main factors limiting the ethylene and propylene market [9].
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).
It consists of Kevlar and other polyamides LC polymers. This surfactant have a hydrophilic and hydrophobic part. In concentrated system, liquid crystal forms due to packing of micelles. This basically gives an idea about different polymers and possible attachments on polymers. An example of such a polymer is Kevlar and polyamides.
Birth control implants are becoming an increasingly popular method of birth control. They are preferred by some women over other contraceptive methods due to their extreme effectiveness, discreetness, fast reversibility, ability to be used while breastfeeding, and lack of medication to keep up with everyday. The implants first appeared in the 1960s and have since been improved upon to become smaller with less rods and longer lasting effectiveness. The newest and most popular models of the implant consist of an ethylene vinyl acetate copolymer plastic
With the development of modern technologies, people enjoy their lives with higher level of quality. This results in the extension of average humane life time and the rapid changes of age structure of the population in the world. There are increasing demands for replacing the failed tissues on aged people. For example, if injury occurs on knees, the ability to flex the knee will be restricted due to pain. Deterioration of the knee joint would make it difficult to perform everyday activities. Even when you lie and sit, it still feels painful. Knee replacement surgery is a common solution to relief for the pains. These rapid increasing demands of implant demonstrate the new generation of implant materials with better mechanical properties and higher biological performance for the expectation of longer life.
Clive Maier, Theresa Calafut. 1998. ‘Polypropylene: The Definitive User's Guide and Databook’. USA: William Andrew Inc.
This is a polymer which is, if, treated with strong heat, turns into a fire-resistant polymer. On burning no smoke is formed, which makes it convenient as a plastic for aeroplane interiors. When PHA is intensely heated, it loses water and re-arranges to form PBO. PHA is used as a plastic as it is easier to mould so it is used instead of PBO.
conjunction with the human body, which plastics are used in prosthetic limbs, and if there
device. prior to this, the plastic material in the form of polymer granules is fed into the
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]
The world has become very dependent upon plastic products. From household items to industry and aerospace, plastic in its many formulations has transformed modern manufacturing and created conveniences and economies unimagined in the early decades of the 20th century.