ISO 12965:2000

Overview

ISO 12965:2000 specifies a laboratory method for determining the microstructure of butadiene rubber (BR / polybutadiene) by infra‑red spectrometry (IR / FTIR). The method uses a cast film of extracted rubber on a salt plate, records a spectrum from 2000 cm⁻¹ to 600 cm⁻¹, and calculates cis, trans and vinyl contents from peak absorbances. The standard includes sample preparation, instrumental requirements, calculation procedures and precision data for repeatability and reproducibility.

Key topics and technical requirements

• Sample preparation

  • Extract rubber (ethanol/toluene azeotrope) per ISO 1407 and dry under vacuum at 50–60 °C.
  • Mill to a thin sheet and dissolve ~100 mg extracted rubber in ~20 ml methylene chloride; filter if gel is present.
  • Cast film on a salt plate and allow solvent to evaporate; target transmittance between 30–50%.

• Instrumentation

  • Double‑beam IR spectrophotometer or FTIR with 2 cm⁻¹ resolution and scale expansion over 2000–600 cm⁻¹.
  • Use a horizontal salt plate and ensure even film casting.

• Measurement and calculations

  • Baseline from 2000 cm⁻¹ to 600 cm⁻¹.
  • Measure absorbances at 965 cm⁻¹ (trans), 909 cm⁻¹ (vinyl), 728 cm⁻¹ (cis).
  • Normalize absorbances and calculate isomer contents (cis, trans, vinyl) using the equations provided in the standard.
  • Report microstructure percentages (cis %, trans %, vinyl %).

• Precision and quality control

  • Repeatability / reproducibility values are given (examples: cis r = 1.00 pp, R = 1.86 pp; trans r = 0.72 pp, R = 0.94 pp; vinyl r = 0.30 pp, R = 0.64 pp).
  • Test report must reference ISO 12965, identify the rubber, note presence of gel, results, deviations, and test date.

Applications and who uses it

• Quality control labs in rubber and tire manufacturing for incoming raw polybutadiene inspection and batch verification.
• R&D and polymer analysis to characterize polymer microstructure during synthesis or catalyst development.
• Suppliers and formulators verifying cis/trans/vinyl content to meet material specifications.
• Accredited testing laboratories performing standardized IR spectrometry for contractual or regulatory compliance.

Practical benefits include consistent microstructure measurement, comparable interlaboratory data, and a defined workflow for IR-based rubber analysis. Users should follow appropriate laboratory safety and solvent handling protocols.

Related standards

• ISO 1407:1992 - Rubber - Determination of solvent extract
• ISO 1795:2000 - Rubber sampling and preparative procedures
• ISO/TR 9272:1986 - Precision for test method standards

Keywords: ISO 12965, butadiene rubber, microstructure, infra-red spectrometry, FTIR, polybutadiene, cis trans vinyl, rubber testing, IR spectrophotometer.