Polyacrylamide and its derivatives for oil recovery

Fourier Transform Infrared Spectroscopy 
Figure 2. 
FTIR spectrum of polyacrylamide crosslinked microspheres
. 
The composition of the dry microspheres was characterized by FTIR spectroscopy 
(Figure 2) and was typical of polyacrylamide. The absorption bands at 3400 cm
-1
and 
3197 cm
-1
are stretching vibrations of N-H. The characteristic absorptions at 1670 cm
-1
and 1418 cm
-1
are vibrations of the C=O (amide) and C-N, respectively, while 
absorptions at 2939 cm
-1
, 2862 cm
-1
, and 1450 cm
-1
reflect vibrations of -CH
2
-. Crosslink 

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149 
structures were not observable in the FTIR spectra since the concentration of crosslinkers 
was less than 0.5wt.-%. 
Thermogravimetric Analysis 
Figure 3. 
Thermogravimetric curve of the PAM micro-gel dry spheres, obtained after 
samples treated isothermally at 105 º
C for 30 min.
 
Thermal properties of the microsphere solids were characterized by TGA.
According to Figure 3, crude dry particles were obtained by removing free water and 
solvent isothermally at 105 º
C. Bulk water and solvent were about 9% of sample mass. A 
3 % weight loss occurred below 250 º
C, due to absorbed and bonded water and solvent in 
the polyacrylamide. As the polar solvent used to wash the products, acetone (b.p. 56 º
C) 
would be expected to constitute the major part of volatile solvents since it could remain 
absorbed during synthesis but was not observed. Meanwhile, polymer can also absorb 

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150 
trace water from acetone and environment. The product had about a 97% non-volatile 
content. 
There are two main thermal degradations of the microspheres, typical of 
polyacrylamide. The first degradation temperature (T
d
) is onset at 270 º
C with a weight 
loss of 18.3 %. The degradation evolves ammonia from thermal imidization of 
polyacrylamide
37-39
removing of unreacted monomer or absorbed solvent, mineral oil.
The main weight loss of 51.1 % onset at 380 º
C results from degradation of the polymer 
chain backbone.