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Introduction to Jiangsu PTFE High-Temperature Fabric Manufacturers: What Effects Does Gamma-Ray Irradiation Have on the Structure and Properties of PTFE?
Views: 0 Author: Site Editor Publish Time: 2026-07-23 Origin: Site
Changes in Chemical Structure: Main Chain Scission and Oxidation
1. Main Chain Scission and Sharp Decline in Molecular Weight
Gamma rays directly break the C-C main chains and C-F side chains of PTFE. Its radiation chemical yield (G-value) reaches 3.0–3.5. Massive chain scission occurs even at extremely low doses, leading to a drastic drop in molecular weight. Manufacturers of PTFE high-temperature cloth in Jiangsu regard this as the fundamental cause of performance deterioration.
2. Free Radical Reactions and Oxidation
Under oxygen-free conditions, free radicals generated by chain scission undergo recombination or disproportionation to form shorter perfluoroalkanes. In an aerobic environment, free radicals rapidly combine with oxygen to form peroxy radicals, triggering chain reactions that further fracture molecular chains and introduce end groups such as acyl fluorides and carboxylic acids. Upon exposure to moisture, acyl fluorides hydrolyze into carboxylic acids and release highly toxic hydrogen fluoride (HF), severely degrading the material.
Changes in Condensed State Structure: Crystallinity and Morphology
1. Crystallinity Rises First and Then Falls
At low doses (typically below 50 kGy), main chain scission produces abundant short chain segments with enhanced mobility, which arrange more readily in an ordered manner and cause an abnormal increase in crystallinity. As the radiation dose increases, numerous defects and degradation products disrupt crystal structures, and crystallinity subsequently decreases.
2. Destruction of Lamellar Crystal Structure
As analyzed by manufacturers of PTFE high-temperature cloth in Jiangsu: WAXS/SAXS results demonstrate that irradiation degrades the original band-like long-period lamellar crystals of PTFE into smaller, fragmented crystallites. The long-range ordered structure disappears, accompanied by thinner crystal lamellae and increased defects.
1. Mechanical Properties (The Most Sensitive Indicator)
Elongation at break begins to decline at merely 0.1 kGy in air, and loses over 90% at approximately 1 kGy. The material completely loses toughness and becomes rigid and brittle. Tensile strength may rise slightly at the initial stage due to increased crystallinity, followed by a rapid decline; elastic modulus increases, while wear resistance and fatigue resistance deteriorate significantly.
2. Thermal Properties
Thinned crystal lamellae and structural defects gradually reduce the melting point from 327 °C to below 310 °C, together with a decreased crystallization temperature. Unstable terminal groups on polymer chains markedly lower the initial thermal decomposition temperature and impair thermal stability.
3. Electrical Properties and Appearance
Polar groups (e.g., carbonyl groups) introduced by degradation slightly raise the dielectric constant and dielectric loss. The material surface changes from white to grey and eventually black, accompanied by severe loss of gloss and embrittlement.
Key Influencing Factors
1. Irradiation Environment (Core Variable)
Degradation damage in air is far more severe than under vacuum or inert atmosphere. Oxygen participates in self-oxidation chain reactions after chain scission, multiplying degradation efficiency and generating harmful end groups. This constitutes the primary limitation restricting PTFE applications under radiation exposure.
2. Total Dose and Dose Rate
Total absorbed dose determines the overall damage level. Under aerobic conditions, low dose rate irradiation causes worse outcomes than high dose rate irradiation. Oxygen has sufficient time to continuously diffuse into the material interior, forming deeper oxidative degradation layers and more uniform and thorough damage, further accelerating the loss of mechanical properties. Therefore, manufacturers of PTFE high-temperature cloth in Jiangsu conclude that PTFE is generally not suitable for radiation environments.
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