IDENTIFICATION AND CHARACTERIZATION OF POLYMERS (UNKNOWN)

Introduction:

TGA measures the amount and the rate of change of the mass of a sample as a function of temperature/time in a system with controlled atmosphere. The data obtained from the graph may be used to identify a polymer and to study its properties like

a)      Moisture content

b)      Compositional analysis of Multi Component System

c)      Estimation of product lifetime

d)      Filler content of the material

e)      Thermal stability

All these can be measured in an inert atmosphere like N2. Changing N2 by Air Oxidative degradation can also be studied which will be reported later.

Five unknown samples were sent to Lab for identification and study of their properties. TGA-DTA was carried out, the polymers were identified and the properties were studied.

Experimental:

The samples were characterized by using TGA.

Following experimental conditions were used:

a)      Instrument
Perkin Elmer STA 6000 (Pyris-6 TGA)
b)     Sample mass
18-20mg
c)      Heating rate
10OC/min
d)     Temperature Range
30OC – 600OC
e)      Sample pan
Ceramic  pan with cover
f)       Purge gas
Nitrogen

TGA-DTA Tharmograms, Explanation of the Graphs for each of the five samples:

ABCDE

Interference and Identification of the Polymers:

Please find the five different TGA curve for these unknown polymers and the data obtained from the graph

SAMPLE
MELTING POINT
MOISTURE CONTENT
DECOMPOSITION TEPERATURE(START)
DECOMPOSITION TEMPERATURE (COMPLETE)
A
137.5 OC
2.20%
1ST POLYMER    200OC
2ND POLYMER   380 OC
1ST POLYMER    380 OC
2ND POLYMER   485 OC
B
137.5 OC
0.75%
1ST POLYMER    200 OC
2ND POLYMER   400 OC
1ST POLYMER    400 OC
2ND POLYMER   500 OC
C
135 OC
0.55%
ONLY ONE         230 OC
ONLY ONE  500 OC      
D
165 OC
0.54%
ONLY ONE         280 OC
ONLY ONE  500 OC        
E
165 OC
0.27%
ONLY ONE         230 OC
ONLY ONE  480 OC      

A and B are composite C is a single polymer.

Sample
Melting point
Name of the polymer
Composition
Filler
Moisture
A
137.5 OC
HDPE
1st Polymer 17.51%
2nd Polymer 72.30%
3.46%
2.20%
B
137.5 OC
HDPE
1st Polymer 14.54%
2nd Polymer 78.54%
3.44%
0.75%
C
135 OC
HDPE
Only one polymer 96.55%
2.30%
0.55%
D
165 OC
PP
Only one polymer 96.37%
0.92%
0.54%
E
165 OC
PP
Only one polymer 98.18%
0.93%
0.27%

Sample A is made up of two HDPE polymers of two different degree of polymerization. The first one is 17.51% and the second one is 72.30%. Moisture content in this polymer is 2.20% and the filler material is 3.46%.

Sample B is made up of two HDPE polymers of two different degree of polymerization. The first one is 14.54% and second one is 78.54%.Moisture content is 0.75% and the filler material is 3.44%.

Sample C is made up of only one HDPE polymer. Polymer presents 96.55%. Moisture content is 0.55% and the filler material is 2.30%.

Sample D and E, both are made up of only one PP polymer. The polymer present in each sample is 96.37% and 98.18% respectively. The moisture and filler materials are 0.54%, 0.27% and 0.92%, 0.93% respectively.

Contributed by:  Ms. Alakta Saha under the guidance of Prof. Barun Gupta

Leave a Reply

Your email address will not be published. Required fields are marked *