Overview
ISO 1264:1980 is an international standard that specifies a method for determining the pH of aqueous extracts from homopolymer and copolymer resins of vinyl chloride. This standardized procedure involves treating a test portion of the resin with a sodium chloride aqueous solution neutralized to pH 7.0, followed by agitation, settling, and measurement of the pH using a pH meter equipped with a glass electrode. The process ensures precise and reproducible pH measurements at a controlled temperature of 23 °C.
This standard is essential for assessing the pH characteristics of vinyl chloride resins, which can impact the selection of additives and stabilizers during compound preparation. Although not intended to estimate electrical qualities of the resin, the pH determination provides valuable information for quality control and formulation in plastics manufacturing.
Key Topics
- Test procedure for vinyl chloride resins: Specifies treating 10 ± 0.5 g of resin with 50 ± 2 ml of 10 g/L sodium chloride solution neutralized to pH 7.0, agitating for 60 ± 5 minutes, and measuring pH after settling.
- Equipment required:
- pH meter with glass electrode and temperature compensation
- 100 ml flask with ground glass stopper
- Mechanical shaker or stirrer
- Pipette and 100 ml beaker
- Measurement conditions: pH measured at 23 ± 2 °C to ensure consistency and accuracy.
- Quality control: pH meter should be regularly calibrated using standard buffer solutions; duplicate determinations are made with acceptable deviation of 0.2 pH units.
- Glassware preparation: Recommends deactivation of glassware through hydrochloric acid treatment to prevent contamination and interference with pH results.
- Expression of results: Reports the arithmetic mean of at least two consistent readings, rounded to one decimal place.
- Reproducibility: Co-operative laboratory tests confirm reproducibility with a variation of ± 0.3 pH units between labs.
Applications
- Quality control in plastics manufacturing: Ensures accurate pH assessment of vinyl chloride homopolymer and copolymer resins as part of product evaluation.
- Additive and stabilizer selection: Helps manufacturers choose compatible chemical additives and stabilizers that function effectively with a given resin pH.
- Formulation and compound preparation: Provides reliable pH data to optimize resin processing and compound stability.
- Regulatory compliance and standardization: Facilitates consistent and recognized test methods across industries dealing with vinyl chloride plastics.
- Research and development: Supports the testing of new formulations and modifications in vinyl chloride resin products.
Related Standards
- ISO 290: Plastic Materials - Preparation of Test Specimens - Guides specimen preparation for plastics testing.
- ISO 846: Plastics - Evaluation of the action of microorganisms - Evaluates resistance of plastics to microbial degradation.
- ISO 9001: Quality Management Systems - Underpins quality assurance procedures applicable in resin manufacturing and testing.
- ISO/TC 61: Plastics Technical Committee - The committee responsible for the development of plastics standards including ISO 1264.
Keywords: ISO 1264, vinyl chloride resin, homopolymer, copolymer, pH determination, aqueous extract, plastics testing, pH meter, sodium chloride solution, resin additives, stabilizer selection, plastics quality control, standardized test method.
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