When modern man discovered plastic and its myriad of uses, there was no turning back. Today, plastics figured prominently in the lives of 21st century people. It is almost impossible to live comfortably without this substance. And among the many kinds of polymer there is perhaps nothing more versatile and very much in demand than acrylic polymers.
This paper will look into the chemical properties and the myriad of uses for the compound normally designated as PMMA or Polymethyl methacrylate.
Acrylic acid (H2C – CHCOOH) was synthesized in 1843 according to Charles Carraher (2003, p. 160). Then he goes to add that ethyl methacrylate (H2C – C(CH3)COOC2H5) was synthesized and polymerized in 1865 and 1877, respectively (2003).
With regards to polymerization e.g. acrylic or methacrylic acid, it must be done in an aqueous solution at less than 20-30% concentration (Feldman & Barbalata, 1996). “Besides water, a conventional recipe involves an initiating system (potassium persulfate and sodium thiosulfate) and chain transfer agent” (Feldman & Barbalata, 1996).
Acrylic polymer is derived from the monomer methyl metharcrylate or MMA. Polymers can be divided into two groups: thermoplastics and thermosets. And that majority of them are thermoplastics meaning once the polymer is formed it can be heated and reformed over and over again (see American Chemistry Council, 2007). This major attribute alone is enough to make scientists and businessmen to be very interested in the application of the product. But interestingly there are many more surprises up the sleeves of the thermoplastic polymer.
The following attributes can be seen in most polymers and especially so to acrylic polymers:
1. Has a light transmittancy of about 92% – with particular clarity at lower wavelength of 270 to 350 nm (Whitaker, 1996)
2. Has good resistance to weathering
3. Good mechanical strength
4. Dimensional stability along with high tensile and flexural strength (Whitaker, 1996)
5. Chemical resistance – including salts, bases, aliphatic hydrocarbons, fats and oils, most common gases, and inorganic chemicals as well as dilute and concentrated solutions of most alkali
According to Feldman and Barbalatat, the most important usage of acrylic polymer is in the manufacture of adhesives, thickeners, coatings, flocculants, dispersants, fluidizers, in cosmetics, pharmaceuticals, ion exchange processes and textile processing (1996).
Now, a few years after acrylic polymer was first introduced by the scientific community, the said substance was first used as interlining for automobile windshields (Carraher, 2003). Since acrylic polymers exhibit good resistance to weathering it is widely used in thermoformed signs, aircraft windshields, and bathtubs.
Acrylic polymers have long been used in the manufacturing of cuvettes, tubing connectors, speculums,and many other medical devices requiring impact strength, chemical resistance, biocompatibility, and clarity. In fact it occupies a, “…prominent place in the market for clear, disposable plastic – only glass transmits light as well” (Whitaker, 1996).
In the medical field, acrylic polymers have shown its versatility and all around usefulness. From the start medical professionals were already well acquainted with the substance because it was used in the manufacture of incubators.
In 1955 its range of usage was expanded when the first acrylic prosthesis was implanted. This probably came after its success as a primary material for aircraft canopies during World War II – pilots suffered fewer infections from shards of acrylic than they had from glass (Whitaker, 1996).
Aside as an important component of cuvettes and tubing connectors, it is also used to produce test kits, luers, drainage wands, syringes, blood filters, blood pump housings, fluid silos, surgical blade dispensers, surgical trays etc.
Finally, acrylic polymers is not only superior in terms of chemical resistance, clarity as a thermoplastic, and durability which is highly prized in the medical field. This substance is also easily recyclable, “Acrylic burns extremely clean […] with end products of carbon dioxide and water. In addition, the material offers superior recyclability: acrylic can be reground and reused, which results in less material waste during molding” (Whitaker, 1996).
But there is more. The said material can be depolymerized back to its monomer, thoroughly purged of its impurities, and then can go full circle back into PMMA. This is a true recycling process, whereas most other recycling processes involve crushing the material and using it in applications with lower specifications (Whitaker, 1996).
In the world of plastic, acrylic polymers belong to the top shelf. The range of its applications is a great help in the development of many industries especially in the medical field. Among other things it has provided cost-efficiency and safety concerning the medical practice and other industrial purposes.
American Chemistry Council. (2007). The Basics – Polymer Definition and Properties.
PlasticResource.com [online] Accessed 08 May 2007 from http: www.plasticresource.com/s_plasticresource/sec.asp? TRACKID=&CID=124&DID=226 Carraher, C. (2003). Giant Molecules: Essential Materials for Everyday Living and Problem
Solving. New Jersey: John Wiley & Sons, Inc. Feldman, D. & Barbalata, A. (1996). Synthetic Polymers: Technology, Properties, Applications. New York: Chapman and Hall. Whitaker, W. (1996). Acrylic Polymers: A Clear Focus. Medical Device Industry [online]
Accessed 08 May 2007 from http: www.devicelink.com/mpb/archive/06/01/001.html.