Can rheological tests accurately determine hydrogel equilibrium modulus and gelation time?

This study outlines a straightforward protocol to accurately determine hydrogel equilibrium modulus and gelation time using a series of rheological tests. These protocols are applied to several hydrogel systems used within tissue engineering applications: agarose, collagen, fibrin, Matrigel™, and methylcellulose.

Does lap shear affect the toughness of polyacrylamide hydrogel?

For the polyacrylamide hydrogel with cuts made by scissors, we have shown that the peak forces in both lap shear and peel scatter significantly, but the plateau force in peel scatters narrowly. As a consequence, the toughness determined by lap shear scatters more than the toughness determined by peel.

How do you test a polyacrylamide hydrogel?

For both types of test, we use two stiff layers to sandwich a layer of a polyacrylamide hydrogel. To use such a specimen to measure toughness, the thickness of the hydrogel must exceed the fractocohesive length, which is ~ 1 mm for the polyacrylamide hydrogel (Liu et al., 2019; Yang et al., 2019).

Can polyacrylamide hydrogels be used as a model material?

Polyacrylamide hydrogels are used in many applications and routinely synthesized in many laboratories. We have used polyacrylamide hydrogels as model materials to study the mechanical behavior of elastic hydrogels (Liu et al., 2019; Yang et al., 2019). For both types of test, we use two stiff layers to sandwich a layer of a polyacrylamide hydrogel.

Can a rheometer test hydrogels with a Peltier temperature control system?

A rotational rheometer with a Peltier temperature control system was used for analyzing the viscoelastic properties of hydrogels. To prevent slip, hydrogels should be tested with a roughened plate, such as a sand blasted or crosshatched plate, shown in Figure 1. This work utilized a crosshatched Peltier plate.

How was the rheometer adapted for the measurement of hydrogel slabs?

The rheometer was adapted for the measurement of hydrogel slabs by sticking sandpaper (grid No 280) to the geometry. The bottom plate was replaced with a Plexiglas® plate with a roughened surface that was fixed on the rheometer with clamps.