ISO 6889:1986 PDF

Name: ISO 6889:1986 — Surface active agents — Determination of interfacial tension by drawing up liquid films
SKU: ISO 6889:1986
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Surface active agents — Determination of interfacial tension by drawing up liquid films

Название (английский):

ISO 6889:1986

Surface active agents — Determination of interfacial tension by drawing up liquid films

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 10
Дата публикации:: 20 марта 1986 г.
Издание:: ISO IS 6889 edition 2 version 1
ICS:: 71.100.40

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Описание (английский):

The determination is carried out in the following way: Measurement of the maximum force which can be exerted before the film breaks, the force being exerted vertically on a stirrup or ring, in contact with he interfacial liquid film between two immiscible liquid phases placed in a measuring cup, in order to draw up the interfacial film. The force must pass through a maximum, otherwise the measurement is not valid.

Abstract

Похожие стандарты

Стандарты, упомянутые в описании

Overview

ISO 6889:1986 specifies a standardized laboratory method for determining interfacial tension between two immiscible liquid phases (typically one aqueous and one organic) by drawing up liquid films. The technique measures the maximum vertical force a platinum‑iridium stirrup or ring can sustain while pulling an interfacial film from the interface until rupture. This simple, reproducible method is intended mainly for control testing of systems containing surface active agents (surfactants) in the interfacial tension range of about 4–50 mN/m.

Key topics and technical requirements

Principle: measure the maximum force (difference before/after film draw) exerted on a stirrup or ring in contact with the liquid‑liquid interface; the force must pass through a clear maximum or the reading is invalid.

Apparatus: a tensiometer with vertical micrometer (0.1 mm resolution), dynamometer (accuracy ≥ 0.1 mN), junction piece with zero indicator, and a shielded assembly to avoid drafts/vibrations.

Measuring unit: platinum‑iridium stirrup (wire ≤ 0.1 mm, specified arm lengths and counterweight balls) or ring (0.3 mm wire; circumference 40–60 mm) and a glass measuring cup (min. 8 cm diameter, 4 cm height).

Sample preparation & control: solutions prepared with double‑distilled water (ISO 2456), temperature maintained within ±0.5 °C, and care to avoid foaming, droplets or contamination.

Cleaning: detailed cleaning procedures (sulfo‑chromic acid, concentrated phosphoric acid, potassium persulfate/sulfuric acid, or solvent treatments for silicone contamination); rings may be flame‑dried in methanol.

Calibration: calibrate each measuring unit using a standard two‑phase system of mutually saturated, pure liquids with known interfacial tension and similar densities; apply same volumes as test samples.

Precision & limitations: suitable when reproducibility of about 2 mN/m is acceptable. Not applicable to systems containing cationic surfactants (see ISO 9101 – drop volume method). Measurements near Krafft or cloud point temperatures may be unreliable.

Practical applications

Routine quality control in chemical, detergent, cosmetics and formulation laboratories where surfactant systems are tested.

Comparative monitoring of interfacial behavior (e.g., emulsifier screening, batch-to-batch checks) where moderate precision (≈2 mN/m) suffices.

Calibration and validation of lab tensiometers that use ring or stirrup methods.

Related standards

ISO 862 - Surface active agents: Vocabulary

ISO 2456 - Surface active agents: Water used as a solvent for tests

ISO 9101 - Drop volume method (recommended for cationic surfactants)

Keywords: ISO 6889:1986, interfacial tension measurement, surface active agents, surfactants, drawing up liquid films, tensiometer, ring stirrup method, calibration, laboratory QC

ISO 6889:1986 PDF

Abstract

Похожие стандарты

Overview

Key topics and technical requirements

Practical applications

Who should use this standard

Related standards

Технические детали

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ISO 9101:1987

Surface active agents — Determination of interfacial tension — Drop volume method

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