Conclusion Polymers 2749m

Conclusion The purpose of first experiment from this lab is to perform two different polyesterifications. Phthalic anhydride is reacted with either ethylene glycol or glycerol. Ethyl glycol will react to form a linear polyester and glycerol will result in a cross linked polyester. Both mixtures were heated in aluminum weight boats by a hot plate. The viscosity and brittleness of the two polymers were compared after heating for 5 minutes. Glycerol was the more viscous than ethylene glycol. Glycerol (1,2,3-trihydroxypropane) has three -OH groups per molecule. On the other hand, ethylene glycol (1,2-dihydroxyethane) has two -OH groups. The viscosity depends on the amount of hydrogen bonding between molecules. Therefore, the more -OH bonds there are, the more hydrogen bonding can occur. Cross-linked polyester, such as glycerol, are more rigid and brittle when compare with linear polyester. However, linear polyester (ethylene glycol) from the experiment was more brittle compare to glycerol. Experimental errors such as heating one mixture longer or mislabeling the compounds can cause this unexpected result. Polymeric materials are very significance to our life. Polymeric materials are used in soil to improve and promote plant growth. In medical, especially heart valve replacements and blood vessels are made of polymers like Dacron, Teflon, and polyurethane. Plastic containers of all shapes and sizes are made from polymers.