Interestingly, the 10 kGy sensitized PLA samples irradiated at
60 C had a greater crosslink density than samples irradiated
50 kGy at 20 C as determined by the gel tests. In PLA, both
absorbed dose and temperature can be used effectively together to
help crosslink polymers to target specific thermomechanical
properties. In the MA/IBoA gel test samples an opposite trend is
observed. The samples that were irradiated at higher temperature
showed less gel formation. This trend was observed in all MA/IBoA
samples except the samples without TMPTA added. The samples
with no TMPTA showed the same upward trend as the PLA. Independent
analysis of the thermal stability of TMPTA during temperature
cycles, leads us to believe that some premature
polymerization of the TMPTA sensitizer due to background temperature
and temperature from the exothermic acrylate reaction
before exposure to the radiation and during early stages of exposure
leads to this reduction of properties. We seek to understand
the limits of this effect through the addition of inhibitors such as
MEH-Q into the polymer blend before 3D printing to help stabilize
the system during melt-processing and subsequent irradiation in
future inquiries.