I'm using an extrusion of LDPE, 640i. ID .032" Wall .005". I have a process where I re-flow the extrusion, using a mandrel,FEP heatshrink and hotair. I have noticed that my pre reflow process tensile strength is about 2x of what my post reflow process strength is. Also, post process elongation is about 3x what the pre process elongation is. I believe that is telling me that the material is being annealed, and becomes more amorphous during the process.
The ID and OD do not change significantly during the process step. I used a thermal couple under the FEP heatshrink to measure the actual temperature that the material is exposed to during process, and the temperature was 425F. I tried lowering the temperature to see if that had an effect on the tensile strength of the post process material, and there was no difference. Still about half of pre process material strength.
Can someone explain what is happening? Why does the material loose half of it's tensile strength, and can I do some post processing to gain the tensile strength back? ?( Maybe irradiate the parts to recross link?)
Thanks in advanced.
Can someone explain what is happening? Why does the material loose half of it's tensile strength, and can I do some post processing to gain the tensile strength back? ?( Maybe irradiate the parts to recross link?)
Thanks in advanced.