Weatherability

Weatherability of Fluoropolymers: Enhancing Durability and Performance

Weatherability refers to the ability of a material to withstand long-term exposure to outdoor conditions, including sunlight, humidity, and other environmental factors. For outdoor scene applications, weatherability is one of the key factors to determine whether fluoropolymer materials are suitable for different applications.

While the chemical and thermal stability of fluoropolymers are well-known, their ability to withstand exposure to outdoor conditions is equally crucial. Weathering can lead to the degradation of fluoropolymers, causing changes in physical properties, such as discoloration, surface roughness, reduced mechanical strength, and loss of transparency. Understanding the weatherability of fluoropolymers is vital to ensure their longevity and reliability in demanding applications.

Example of weatherable fluoropolymer structure [1]

Why Are Fluoropolymers Weather Resistant?

Fluoropolymers are weather resistant primarily because of the strong chemical bonds formed between carbon and fluorine atoms in their molecular structure. This combination of atoms results in several properties that contribute to their weather resistance:

• Chemical inertness
  Fluoropolymers exhibit high chemical resistance and are highly unreactive to most chemicals. This makes them resistant to corrosion and degradation when exposed to harsh weather conditions and chemicals present in the environment.
• Hydrophobicity
  Fluoropolymers are highly hydrophobic, meaning they repel water and do not absorb moisture. This property prevents water from penetrating the material and causing damage, such as swelling, warping, or cracking, which can occur in other polymers upon exposure to moisture.
• UV resistance
  Fluoropolymers have excellent resistance to ultraviolet (UV) radiation from the sun. The strong carbon-fluorine bonds in their structure allow them to withstand prolonged exposure to UV light without degrading. This property helps prevent color fading, deterioration, and embrittlement that can occur in other polymers exposed to sunlight.
• Thermal stability
  Fluoropolymers have a high melting point and can withstand extreme temperature variations, making them resistant to thermal degradation. This stability allows them to resist damage from heat, cold, and temperature fluctuations commonly experienced in outdoor weather conditions.

Factors Influencing Weatherability of Fluoropolymers

The weatherability of fluoropolymers can be influenced by several factors and external conditions. Some of these include UV radiation, temperature, humidity and moisture, chemical exposure, mechanical stress, environmental pollutants, and ageing, etc. Alfa Chemistry's analytical testing platform can provide you with a series of testing services to evaluate the weatherability of fluoropolymers.

• The energy from UV rays can break down the polymer chains, leading to a reduction in physical and mechanical properties.
• High temperatures can accelerate the degradation of fluoropolymers.
• Moisture can penetrate fluoropolymers and induce hydrolysis, causing chain scission and weakening the material.
• Although fluoropolymers are generally resistant to many chemicals, exposure to certain substances can degrade their performance.
• Repeated mechanical stress, such as impact or flexing, can lead to physical degradation of fluoropolymers.
• Over time, even in the absence of external factors, fluoropolymers can undergo gradual degradation due to internal interactions and reactions within the polymer matrix.

Weatherability Comparison of Fluoropolymers

Fluoropolymers	Forms	Weatherability
		UV Resistance	Hydrolysis Resistance	Ozone Resistance
PTFE	Fluoropolymer Fluoropolymer films Fluoro coatings Polymer additives	☆☆☆	☆☆☆	☆☆☆
FEP		☆☆☆	☆☆☆	☆☆☆
PFA		☆☆☆	☆☆☆	☆☆☆
PCTFE		☆☆	☆☆	☆☆
ETFE		☆☆	☆☆	☆☆
Fluoroelastomer		☆☆	☆☆	☆☆

Reference

1. Ameduri B. Chemistry-A European Journal, 2018, 24(71): 18830-18841.