To measure the gel time
of the different lignin phenolic resins, a Sunshine 22A gel time
meter was used.
Increases in accelerator concentration decreases the gel time
Thus, the VNC has clearly distinguished between the character of these two cures, despite the fact that the catalyst levels had been adjusted to give both formulations the same gel time
The primary objective of the present study was to investigate the effect of chain extender content on the gel time
and its temperature dependency in thermosetting PU formulations using rheological approaches.
The gel time
was determined under isothermal conditions at 80[degrees]C and established as the point corresponding to the crossover between the elastic (G') and viscous (G") moduli curves (12), (13).
The gel time
and rise time for the foaming of both conventional and nanocomposite foams are given in Table 2.
For both the 12- and 40-nm nanocomposites, the gel time
is reduced with increasing silica content.
Considering that the gel time
of this EMC is 41 s and the rise in viscosity by curing occurs in 12-13 s as shown later, this flow stop is not caused by curing but by the yield stress.
The duration of time depends on the solution gel time
of the nanocomposites.
CCP's new OptiPlus MC 040-8089 (standard gel time
) and 040-8094 (extended gel time
, summer version) can be substituted for the original OptiPlus 040-8077 resin, which is still available.
Peak exotherm temperature and gel time
were determined in accordance with ASTM D2471-88 using 120 ml of resin-curing agent mixture in [1/4] pt can.
This particular experimental technique may be considered an efficient method, since it is able to correlate the reactivity of an epoxy system with the measured gel time