Product Overview

IOTA 255 is a methyl/phenyl copolymerized polymethylphenylsiloxane fluid. The phenyl segments significantly enhance thermal stability, oxidation resistance, and radiation resistance, giving it a much wider working temperature range than conventional dimethyl silicone oils, while retaining the low pour point, low surface tension, and excellent lubricity typical of silicone fluids.

The product is a colorless to pale-yellow transparent liquid with viscosity covering 75–1400 cSt (25°C), open-cup flash point ≥280°C, and pour point ≤-40°C, meeting needs from precision damping to high-temperature heat transfer.

Key Features 

• Wide working range: –60°C to 320°C — no decomposition at high temperature, no freezing at low temperature.

• Good thermal stability and oxidation resistance: phenyl structure delivers excellent heat-aging resistance.

• Radiation resistance: suitable for applications with radiation exposure.

• Water stability: performance does not easily degrade in the presence of water.

• Good lubricity: usable directly as a high-temperature lubricating oil and as base oil for high-temperature greases.

• Wide viscosity selection: 75–1400 cSt (25°C), with grades matched to applications.

• High flash point: ≥280°C (open cup) for safe high-temperature operation.

• Low pour point: ≤-40°C, remaining workable in severe cold.

Technical Data Sheet at a Glance

Main Applications

1. High-temperature heat-transfer medium for insulation, lubrication, damping, shock-absorption, and dust-proofing service;

1. Base oil for high-temperature lubricating oils and greases: long-term lubrication of bearings, chains, and hot spots;

1. Damping and shock-absorption fluid: damping medium for precision instruments, gyroscopes, and dampers;

1. Electrical insulation and encapsulation: high-temperature insulating service;

1. Radiation-exposed environments: special scenarios leveraging its radiation resistance.

Frequently Asked Questions (FAQ)

Q: What is the chemical name of IOTA 255? A: Polymethylphenylsiloxane.

Q: What is the working temperature range of IOTA 255? A: –60°C to 320°C. It remains thermally stable at high temperature and stays fluid down to a pour point of ≤-40°C.

Q: What viscosity grades does IOTA 255 offer? A: 75–1400 cSt at 25°C; select the grade that matches your application.

Q: How does IOTA 255 differ from dimethyl silicone oil? A: With its higher phenyl content, IOTA 255 offers better thermal stability, oxidation resistance, and radiation resistance over a wider range (–60°C to 320°C), making it better suited to harsh high-temperature and radiation environments than dimethyl silicone oil.

Q: Can IOTA 255 be used as base oil for high-temperature grease? A: Yes. It is an ideal base oil for high-temperature lubricating oils and greases, and also serves as a high-temperature heat-transfer medium.

Q: What is the flash point of IOTA 255? A: ≥280°C (open cup), ensuring safe high-temperature operation.