Overview
ISO 4608:2023 - Plastics - Homopolymer and copolymer resins of vinyl chloride for general use - Determination of plasticizer absorption at room temperature - specifies a laboratory method to measure how much plasticizer a PVC general‑purpose or filler resin absorbs at ambient conditions. The test gives a practical indication of plasticizer uptake for producing dry blends and for quality control of vinyl chloride resins used in plasticized formulations.
Key topics and requirements
- Scope: Applicable to PVC general‑purpose resins and filler resins designated “G” and “F” in ISO 24024‑1.
- Principle: An excess of plasticizer is mixed with a weighed amount of resin, centrifuged, and the plasticizer retained by the resin is determined gravimetrically.
- Apparatus & materials:
- Balance with accuracy ±0.1 mg.
- Burette or dispenser (see ISO 8655‑2).
- Horizontal‑rotor centrifuge with acceleration at the tube bottoms of 24 500 to 29 500 m·s‑2 (60 min) and temperature ≤ 30 °C.
- Centrifuge tubes (conical bottom with ~0.8 mm hole or with sieve plate) and sheaths.
- Cotton wool (100 mg ± 2 mg) or filter paper; alternative absorbents allowed if equivalent.
- Plasticizers covered: Bis‑(2‑ethylhexyl) phthalate (DOP, CAS 117‑81‑7) and Bis‑(3,5,5‑trimethylhexyl) phthalate (DINP, CAS 28553‑12‑0 / 68515‑48‑0), with specified density, refractive index and viscosity limits as per ISO 1385‑1. Note: DOP use is now restricted in Europe for hazard reasons (CLP/REACH).
- Procedure highlights: Blank measurement of absorbent, weigh tube + absorbent, add specified resin mass and a measured volume/length of plasticizer, centrifuge, reweigh and compute absorbed plasticizer. Results reported as parts per hundred resin (phr).
- Reporting: Include reference to ISO 4608:2023, sample ID, plasticizer type, centrifuging conditions, quantities used, test result, deviations, and date.
Applications and users
- Quality control laboratories in PVC resin manufacturing.
- Compounders and processors producing plasticized dry blends and formulations.
- R&D and material development teams evaluating resin/plasticizer compatibility.
- Regulatory and compliance testing where plasticizer uptake affects product performance or safety.
The method supports decisions on plasticizer selection, dry‑blend formulation, batch acceptance and troubleshooting of mixing/compatibilization issues.
Related standards
Keywords: ISO 4608:2023, plasticizer absorption, PVC, vinyl chloride resins, DINP, DOP, centrifuge method, room temperature absorption, dry blend, plasticizer uptake.
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