【国外标准】 Standard Practice for Separation and Identification of Poly(Vinyl Chloride) (PVC) Contamination in Poly(Ethylene Terephthalate) (PET) Flake

5.1 Presence of even low concentrations of PVC in recycled PET flakes results in equipment corrosion problems during processing. The PVC contamination level shall dictate the market for use of the recycled polymer in secondary products. Procedures presented in this practice are used to identify the PVC contamination in recycled PET flakes.NOTE 4: These procedures may also be used to estimate the concentration of PVC contamination.1.1 This practice covers four procedures for separation and qualitative identification of poly(vinyl chloride) (PVC) contamination in poly(ethylene terephthalate) (PET) flakes.NOTE 1: Although not presented as a quantitative method, procedures presented in this practice may be used to provide quantitative results at the discretion of the user. The user assumes the responsibility to verify the reproducibility of quantitative results. Data from an independent source suggest a PVC detection level of 200 ppm (w/w) based on an original sample weight of 454 g.1.2 Procedure A is based on different fluorescence of PVC and PET when these polymers are exposed to ultraviolet (UV) light.1.3 Procedure B is an oven test based upon the charring of PVC when it is heated in air at 235°C.1.4 Procedures C and D are dye tests based on differential staining of PVC and PET.NOTE 2: Other polymers (for example, PETG) also absorb the stain or brightener. Such interferences will result in false positive identification of PVC as the contaminant.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazards see Section 8.NOTE 3: There is no known ISO equivalent to this standard.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.