Kearns_Experiment 2

Kearns_Experiment 2 - Experiment 2, Differential Scanning...

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Experiment 2, Differential Scanning Calorimetry (DSC) of Poly(ethyleneterephthalate) Author: Jeremy Kearns Group 6 Section 1, M 1:25 PM – 4:25 PM Partner: Tyler Smith 3/7/2011 Abstract: This experiment uses Differential Scanning Calorimetry (DSC) in order to measure the enthalpy of fusion, enthalpy of recrystallization, glass transition temperature, and temperature of fusion of quenched and unquenched poly(ethylene terephthalate) (PET) from a plastic soda bottle. From these measurements, the entropy of fusion was also calculated. The enthalpies of fusion of quenched and unquenched PET were respectively found to be 42.92 and 53.45 J/g. The respective entropies of fusion were found to be 0.18 and 0.23 J/g o C. When comparing the DSC scans, there was no recrystallization peak for the unquenched sample, but there was one present for the quenched sample. The weight percent of diethylene glycol (DEG) was also measured for each sample. The unquenched sample was 5.71 wt. % DEG and was 25.85% crystalline. The unquenched sample was 6.19 wt. % DEG, and had a 9.90 and 32.20% crystallinity before and after its recrystallization peak. I. Introduction Many properties of polymers can be measured using Differential Scanning Calorimetry (DSC). Such properties as heat of fusion (ΔH fus ), crystalline fraction (f c ), entropy of fusion (ΔS fus ), onset temperature (T f ), and temperature of fusion (T fus ) can all be calculated using a DSC.
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Experiment 2, Differential Scanning Calorimetry of PET Poly(ethylene terephthalate) (PET) is a condensation polymer that is commercially prepared using two steps. The first step involves either transesterification or direct esterification to form a diol ester and low molecular weight oligomers. The second step consists of a melt polycondensation step. PET is usually prepared to be in a partially crystalline form, which is, in effect, a series of crystallites in an amorphous matrix. This experiment will look at the fraction of crystallinity of PET from a sample obtained from a plastic soda bottle. Many of the mechanical properties of PET are strongly dependent upon the fraction of the polymer which is in the crystalline form. In order to calibrate the DSC for the purposes of this experiment, an indium sample will be first run to experimentally determine if a calibration factor was necessary in the melting temperature and enthalpy of fusion of the PET samples. If the indium is too far out of the range of a literature value, then adjustments will have to be made until the experimental melting
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This note was uploaded on 03/08/2011 for the course CHEM 232 taught by Professor James during the Spring '11 term at Clemson.

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Kearns_Experiment 2 - Experiment 2, Differential Scanning...

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