Hello All,
I have a product that has blue colour master batch inside, it is an irradiated polypropylene copolymer.
I would like to find out the exact grade of this PP, is there a method of doing this ? I have the DSC peak of this and the Tp sits around 153C.
The material is gamma stable.
Any ideas would be highly appreciated. Thanks
The exact grade (i.e. manufacturer and type number) probably cannot be determined by analysis. From the DSC melting point it seems that you have a PP homopolymer or a copolymer with substantial amount of PP blocks. If you do not see PE melting, it means that either you do not have PE block or very short ones. I would suggest to make WAXS (Scherrer diffractogram) which tells you the crystalline structure (the polymer, perhaps even that of the pigment - it the latter is crystalline). If you perform TGA/DTA and if the pigment is thermally stable, you can find out the pigment content (and thus the matrix content). From the DSC and the matrix content you can calculate the degree of crystallinity which you may try to compare with the crystallinity determined form WAXS. Additionally you may try to do melt rheological tests of the masterbatch and then you will get the maximum possible information on your system.
Thank you Gyorgy Banhegyi, your answer is very helpful. The DSC is conducted at 20C/min. There is some colour masterbatch inside, however it must be very small weight proportion. indeed, I was thinking of melting it to see its MFI. I have a guess at the moment after doing some research, next step seems like getting some granules to injection mould a new part and see if it has similar properties. I wish we could spot the material straightaway after few XRD analyses like with the metals. Polymer world is so complicated.
Usually the amount of material used for DSC is about 10 mg. Typically high concentration masterbatches contain maximum 40-50 wt% filler. If you make ATR-FTIR and compare the obtained spectrum with a typical PP spectrum, you will see what is the probable nature of the pigment. Inorganic pigments usually absorb at relatively low frequencies. You may also try to perform Soxhlet extraction of the masterbatch with a non-polar, low boiling solvent. If you have a wax-like additive, you will observe more dissoved component after drying. If you use hih boiling solvent, such as xylene, you may dissolve more of the matrix polymer. You can even compare the properties (DSC, TGA, IR, X-ray) of the extracted and the original masterbatch and you may draw certain conclusions on the matrix. A SEM analysis combined with EDAX may tell you something about the elemental composition of the pigment too.
Thank you very much for your answers, I have a guess, however made the guess through investigation of the research papers of this product's brand. It is a global company that has plenty of patents/ research papers of this particular product. it was pretty easy to make a guess after couple of hours research into their documents :) next step is injection moulding / extruding these granules into the same geometry and testing it against the product I have in hand.
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