Lachlan Bryant Chemistry Ms Bishop
Polycarbonate vs. Acrylic
In this report I will thoroughly discuss the chemical properties, makeup and effectiveness of the polymers polycarbonate and acrylic. I will evaluate the current use of each and conclude which is better and more efficient in various situations. To understand this topic, a full understanding of polymers is required.
A polymer is more commonly referred to as a plastic. The simplest definition of a polymer is something that has been made by many units although they are much more complex than this. A polymer is much like a chain; each link of the chain is the monomer or base unit. This monomer or base unit is usually made of carbon, hydrogen, oxygen and/or silicon. The chain is composed of many of these monomers polymerised together, or in this analogy, many links of the chain joined together. Polymerisation is simply the linking of the monomers to form the polymer (American Chemistry, 2007).
Figure 1 shows the chemical structure of a simple hydrocarbon. Sourced from AmericanChemistry on 6 March 2009.
Figure 2 shows the chemical structure of polycarbonate. The two phenyl groups and the CH3 (not explicitly labelled but still represented) can be seen. Sourced from Buffalo education, March 6 2009
To fully understand the properties of polycarbonate, one must understand why the properties are the way they are. To the left is a diagram of the chemical structure of bisphenol-A. In this diagram two six-sided honeycomb shaped structures can be seen. These are called
Figure 4 shows a comparison of impact strength between various polymers. Sourced from Polymer Technology and Services, March 6 2009.
The diagram above compares the impact strength of polycarbonate to various other polymers (Paying particular attention to the variation between polycarbonate (PC) and Acrylic).
Although this is an outstanding polymer for a variety of uses, it does have its disadvantages. It has only fair chemical resistance and is attacked by many organic solvents. It is also fairly expensive compared to other plastics.
Some of the many uses of polycarbonate include being an ideal engineering plastic due to its ease of being moulded, blow moulded and extruded including having good electrical insulating properties. This means it is applied in electric meter housing and covers. As well as this polycarbonate is used as casket hardware, portable tool housings, safety helmets (due to its extemely high impact strength), computer parts and even vandal proof windows and bullet proof windows used in large bank safes. The price of polycarbonate makes it more suitable for application mainly in engineering. Another big use of polycarbonate that hasn't been mentioned is plastic lenses in sunglasses due to its high transparency and impact resistance.
Acrylic refers to a family of synthetic polymers that contain one or more derivatives of acrylic acid. The most common of these is polymethyl methacrylate (PMMA). PMMA is a tough, highly transparent material giving it many similarities to polycarbonate which is why the two are in competition. Acrylic has excellent resistance to ultraviolet radiation and weathering. It can be coloured, moulded, cut, drilled, and formed.
Figure 5 shows the chemical structure of Acrylic
Acrylic, being nearly crystal clear is an excellent option for display cases. The thicker Acrylic material can shield against beta radiation. Acrylic is available in a wide array of forms and colours as well as being machineable and bendable. It can be used in a wide range of applications such as aquariums, picture frames, shelves and cabinets.
Compared to polycarbonate, acrylic has a lot lower impact resistance, cannot be bulletproof within a reasonable thickness, less bendable and formable and is harder to work with but on the other hand compared to acrylic, polycarbonate is more likely to scratch, the clarity isn't as high, yellows after time due to the UV light whereas Acrylic doesn't and is a lot more expensive.
The facts presented have proved that there is no definite answer to which is better, Acrylic of Polycarbonate. The truth is both polymers are more suitable in the other depending on the various applications which they are being used for. Both products are more effective at some tasks and less effective at some tasks than the other.