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Evolved gas analyses with pyrolysis were carried out for some kinds of polymer products using a newly developed apparatus of Skimmer interface-connected [TG/DTA]/[Photo-Ionization-QMS] that is “ThermoMass Photo” by Rigaku corporation.The apparatus has an advantage of the real-time monitoring of pyrolyzed species because of no transformation and no retention time of the evolved species using the skimmer interface.The PI technique is one of the soft ionization techniques.The soft ionization for mass spectrometry offers no fragmentation during ionization,so that one peak indicates one chemical species reflecting its molecular weight.In the mass spectrum,evolved species can be distinguished without any separation techniques,such as gas chromatography as pretreatment technique.The combination of soft ionization mass spectrometry and TG/DTA results offers the discrimination of polymers with the same chemical structure and different thermal properties.In the soft ionization mass spectrum,there are some minor peaks due to small amount additives.In general,the small peaks may be ignored as noise.For this purpose,multivariate analysis such as Residual Analysis is effective to identify these minor peaks due to small amount species.In case of usual apparatus such as capillary-connected TG/MS and Py-GC/MS,unstable species evolved by pyrolysis must be adsorbed or transformed on the inner wall of transfer device for evolved gaseous species.Hence it follows that detection of these species is impossible.The software is newly developed,and useful to polymer discrimination by spectrum matching and product comparison by residual analysis.DCR(Different calculation method of regression analysis)offers the spectrum matching,so that discrimination between not only homo-polymers but blended polymers using homo-polymer database only,without database of blended polymers.The software-assisted evaluation has been carried out to blended polymer products.In case of shock-resisted polymer that is mixture of polystyrene and styrene-butadiene copolymer,the result indicated PS∶SB = 78%∶22%,and discriminated that SB was ABA block copolymer with 28 wt%styrene.It is appropriate to the product specifications.