You might try searching for stress relaxation data. This should provide a reference to time and temperature.
Note: there are many different types of PVDF and each manufacturer has different grades.
I suggest measuring the flexural modulus using a Rheometric Scientific RSA II using stress...
The "defect" needs to be verified as 1)already in the material or 2)caused by the machining operations.
Sometimes linear polyolefins (HMWPE, LLDPE, UHMWPE, etc) will crosslink from the heat associated with shearing (machining)the part.
First- ask yourself what are the most important properties.
Second- Send samples to many manufactures of rheometers to perform a test of your materials (Normally Free).
Third- choose a system that can perform the testing, and last a long time in the lab.
Besides the final physical properties, you might want to investigate melt strength and a laboratory that performs blending of polymers on a brabender.
The previous responce included a co-polymer of polystyrene and that would help a great deal, but you must look at compatibility and processibility.
I would have the pvc tested as good verses "bad" and then make a determination as to the grade or quality of pvc needed. Rheology testing or even thermal analysis will predict the difference.
First of all what density of foam are you lookin for?
Also the end use is very important.
The environmant the foam is exposed to is important. The answer to the questions will determine the proper foam to choos and which manufacturer to pick.
Please describe "transparent" to UV and IR wavelengths.
As many have stated all polymers have an infrared spectra. Most also have an ultraviolet spectra. The IR spectra covers the range of 4800 cm-1 to 375 cm-1, and UV light covers 370 nm to 900 nm.
So, do you want low absorbance of these...
All polyethylene foam and co-polymers of polyethylene foam will absorb oil. The University of Toronto has a lab, directed by Dr. Chul Park, that has polycarbonate foam and many other materials.
Fourier transform infrared analysis (FTIR) will verify if the "particles" are starch or a mineral like talc or TiO2.
Many labs can perform the analysis for about $150-$200 dollars.
