Polyacrylamide and its derivatives for oil recovery

Dynamic Rheological Measurement
: 
In DRM, an amplitude sweep is a common method 
consisting of dynamic stress sweeping and oscillatory frequency sweep testing. The 
dynamic stress sweep was carried out with a stress range from 0.1 Pa to 10000 Pa at a 
fixed frequency of 6.28 rad
-1
(i.e., 1 Hz). The oscillatory frequency sweep measured 
resistance stresses over a frequency range of 0.01 to 100 rad
-1
(from 0.00159 to -15.9 Hz) 
in oscillation mode.

Static Rheological Measurement
:
The steady stress sweep was carried out with a stress 
range from 2 Pa to 2000 Pa and maintained for 180 s. Through SRM, a yield stress 
τ
y
was 
determined, defined as the minimum stress required to initiate flow.
Results and discussion 
Structure and morphology of PVA/PAM IPN hydrogel 
A series of PVA/PAM IPN hydrogels over a range of PVA contents were 
prepared by in-situ free radical solution polymerization of AM and MBAM, with a 
concurrent chemical crosslinking of PVA. The composition of the IPN hydrogels is listed 
in Table 1. The representative crosslinking structures are proposed in Figure 1. The first 
network contains polyacrylamide crosslinked by N’N-methylene bisacrylamide (Figure 
1a) whereas the second network is obtained by a crosslinking of poly(vinyl alcohol) by 
glutaraldehyde under an acidic environment (Figure 1b).[47,48] 

---

173 
Table 1 
Composition of PAV/PAM IPN
 
(a) 
(b) 
(c) 
Fig. 1 
(a).
 
The first network: polyacrylamide with N, N-methylene bisacrylamide as 
crosslinker; (b). The second network: poly (vinyl alcohol) –glutaraldehyde; (c). The 
representation of interpenetrating network of PAM/PVA