There are various characteristics and properties of Polymethyl methacrylate (PMMA) that are essential in the improvement of the processing of polymer manufacture. PMMA have been widely used in place of the glass. Consequently, its unique features have been the contributing factors in its applications. The properties of PMMA include:
Weight: The material is always lightweight and even durable.
Density: The material has a density of between 1.15-1.19 g/cm3. This weight is estimated as half the density of a glass material.
Strength: PMMA has a good impact strength which is significantly lower than the strength of the polycarbonate as well as other engineered polymers. In addition, the strength of the PMMA is estimated to be higher than the strength of polystyrene and the glass. Precisely, PMMA has a distinct high mechanical strength and a low elongation at break (Koleva, 2006).
Temperature: PMMA ignites at the temperature of 460 °C, which cause the material to burn with the products of combustion being water, Carbon monoxide, Formaldehyde and the Carbon dioxide (Koleva, 2006). In addition, variation in temperature affects the mechanical properties with PPMA, which makes the material to creep. Further, PMMA is the most resistant polymer to direct exposure to sunshine.
Water Absorption: PPMA exhibits low moisture and water content capacities, estimated to be between 0.3-2% for the water absorption and 0.3-0.33% of the absorption of moisture at the equilibrium (Koleva, 2006).
Applications of PMMA
PMMA’s physical and chemical properties make it suitable for various applications. The properties such as its being transparent strong, durable and transparent make it suitable in the manufacture of rear-lights and lenses for glasses. The versatility of PMMA also makes the material applied in the production of various instrument clusters for the motor-vehicles (Bronzino, 2000).
The strength of the material combined with its water absorption capacity make the material to useful in the manufacture of windows, sanitary ware, furniture, and LCD screens, among others (Bronzino, 2000). The material’s resistance to the exposure of sunlight and the effects of UV rays has made it useful in the coating of polymers. The above is due to its stability when exposed to various environmental situations such as moisture and sunlight (Bronzino, 2000).
In addition, PMMA stability and purity have also been used in dental and medical fields. Its compatibility with the human tissue has also been exploited in the manufacture of intraocular lenses. Further, it is applied in the bone cement to fix implants. The transparent appearance of PMM makes is suitable for its use in patient’s teeth and production of ocular prostheses (Bronzino, 2000). Therefore, the physical and mechanical properties PPMA combined with the properties of other polymers enhance the manufacture of better materials with maximum mechanical properties.
How to Improve the Processing of PMMA
PMMA have been established to cement in joint replacement. Consequently, its appropriateness for the use has been enhanced by its properties that make it have a high degree of compatibility with the human tissues. Various studies that were carried out with PMMA established that it was appropriate in cementing bones (Zhao, 2003; Yang et al., 2010). The major limitation of using PMMA in cementing bones is its high heating of up to 82.5°C. The high heat was established to cause the neighboring tissues a thermal necrosis. Other limitations are cement fragmentation and prosthetic loosening. Therefore, to ensure that PMMA makes a good cementing material, Vaishya et al. (2013) recommends the use of nanoparticle additives and to increase the degree of surface roughness of bones. In addition, the combination of NMRP and the ATRP techniques, and the binary mixed PMMA brushes will improve the cementing of bones. ATRP involves a series of transfer of the radical polymerization atoms whereas NMRP is nitroxide-mediated.
Processing of PMMA by Radical Polymerization of MMA
The materials required are AIBN and the BP, and a temperature of up to 60 °C. The process involved in the processing of radical polymerization of the MM requires that Methyl methacrylate is distilled twice under bp 48 °C. The above is followed by crystallization of BP and AIBN thrice after which, they are dried in a vacuum. NMR spectroscopy is then applied to control the purity of the mixtures. AIBN and the BP enhance the decrease in the maximum time of conversion (Zhao, 2003). Additionally, while polymerizing the MMA, a lower cobalt concentration is usually maintained with respect to that of the compounds. A temperature of about 20°C is often used to obtain a high concentration of the complex substance in MMA that is usually about 0.5mmol dm -3. Further, the iron-containing the complex 1 is usually used in the polymerization process since it is an efficient compound. Also, the pivalate metal complexes are typically used to accelerate the process.
Bronzino, J. D. (2000). The biomedical engineering handbook. Boca Raton, FL: CRC Press. Retrieved from < http://books.google.co.ke/books?id=T2UIoAxcFdIC&printsec=frontcover&dq=bronzino,+%282000%29+the+biomedical+engineering+handbook&hl=en&sa=X&ei=iuhrVOCQBajXyQP_2IG4BA&redir_esc=y#v=onepage&q=bronzino%2C%20%282000%29%20the%20biomedical%20engineering%20handbook&f=false >
Koleva, M. (2006). Poly(methyl methacrylate) (PMMA): Injection Moulding Materials.
Vaishya, R., Chauhan, M., & Vaish, A. (2013). Bone cement. Journal of Clinical Orthopaedics
and Trauma, 4(4), 157-163.
Yang, D. T., Zhang, D., & Arola, D. D. (2010). Fatigue of the bone/cement interface and
loosening of total joint replacements. International Journal of Fatigue, 32(10), 1639-1649.
Zhao, B. (2003). Synthesis of binary mixed homopolymer brushes by combining atom transfer
radical polymerization and nitroxide-mediated radical polymerization. Polymer, 44(15), 4079-4083