ShopComparative Study on Chemical Stability and Mechanical Properties of ETFE and PTFE Films
Sep
In modern architecture, industrial anti-corrosion, environmental engineering and other fields, film structure materials have become key materials driving engineering innovation. The advantages of these materials include lightweight, large span and high adaptability. Among these, PTFE and ETFE films are the most common fluorine-based film materials. However, there are significant differences between their core performances, which directly impact their application scenarios and engineering value.
- Chemical stability
PTFE:
The molecular chain of PTFE is composed of repeating units of the formula “-CF₂-CF₂”. The strong electronegativity of fluorine atoms creates a protective layer that resists the erosion of most chemical substances. It is commonly referred to as the “King of Plastics”, and its chemical stability is evident in the following ways.
- Acid and alkali resistance
PTFE has been demonstrated to be a stable material which does not react with strong corrosive media, such as concentrated hydrochloric, sulphuric, nitric acids (at room temperature) and strong alkalis. Despite prolonged exposure to these media, there is no evidence of dissolution, swelling or deterioration in performance. The destruction of PTFE will only occur under conditions of extreme temperatures, such as when exposed to molten alkali metals or fluorine elements at temperatures above 200°C.
- Resistance to organic solvents
PTFE demonstrates complete resistance to a range of common organic solvents, including ketones, esters, alcohols, and aromatic hydrocarbons, without undergoing dissolution or penetration. It’s suitable for scenarios such as chemical storage tank linings and organic solvent filtration films.
ETFE:
The copolymerization of ethylene (CH₂-CH₂) and tetrafluoroethylene (CF₂-CF₂) has been utilized to synthesize ETFE, with the incorporation of non-fluorine ethylene units into the molecular chain. While ETFE maintains the corrosion resistance of fluorides, its capacity to endure extreme environments is inferior to that of PTFE.
- Acid and alkali resistance
ETFE exhibits an excellent tolerance to dilute acids, dilute alkalis and neutral salt solutions, and is capable of resisting the erosion of rainwater and mild industrial wastewater. However, it is not capable of withstanding strong oxidizing acids or strong alkalis at high temperatures. Prolonged exposure to these materials is likely to result in molecular chain disruption of ETFE, giving rise to issues including embrittlement and reduced light transmittance.
- Resistance to organic solvents
ETFE exhibits considerable resistance to alcohols and water-based solvents; however, it may undergo slight swelling when subjected to strong polar organic solvents or prolonged exposure to oily substances, affecting its mechanical properties.
- Mechanical property
PTFE:
PTFE molecular chains are characterized by high rigidity and crystallinity. Their mechanical properties evince pronounced rigidity and low flexibility, which is manifested in the following manner.
- Tensile strength and elongation at break
At room temperature, the tensile strength of PTFE is approximately 20 to 30MPa, while the elongation at break is only 10% to 30%. Its mechanical property is characterized by high hardness and brittleness, with the capacity to withstand certain static loads when there is no significant deformation. If the tensile strength exceeds the limit, PTFE is susceptible to brittle fracture.
- Creep resistance
PTFE exhibits exceptional creep resistance, which refers to the ability of the material to resist slow deformation under prolonged external forces. Additionally, PTFE has remarkable dimensional stability under long-term static loads, such as the self-weight of a building roof or snow load, thereby ensuring the integrity and reliability of the structure over an extended period. It is particularly well-suited for large-span fixed film structures, such as the roof of airport terminals.
ETFE:
The incorporation of ethylene units within the ETFE molecular chain leads to a reduction in molecular crystallinity and an augmentation in the fluidity of the chain segments. Consequently, the mechanical properties of ETFE are manifested as high flexibility and high elasticity, rendering it more suitable for scenarios necessitating dynamic deformation.
- Tensile strength and elongation at break
At room temperature, the tensile strength of ETFE is approximately 30 to 40MPa (higher than that of pure PTFE film), and the elongation at break can reach 200% to 300%. It exhibits an exceptional degree of extensibility, with a high resilience to springback. Even when subjected to a tensile stress of up to 2-3 times its original length, it can still revert to its original shape, reducing the probability for irreversible deformation. It is suitable for inflatable film constructions (including stadium ceilings with air pillows), and foldable flexible structures.
- Creep resistance
The creep resistance of ETFE is weaker than that of PTFE. It is susceptible to slow deformation under long-term static loads, rendering it unsuitable for utilization in large-span structures with long-term fixed loads. ETFE is more appropriate for dynamic loads or adjustable loads.
- The selection suggestionsoriented towards core differences
A comparison of the chemical stability and mechanical properties of ETFE and PTFE films reveals that neither is superior or inferior to the other; rather, they are each suitable for different scenarios. It is imperative that the actual selection process aligns closely with the engineering requirements.
- Scenarios where PTFE films are preferred
Chemical anti-corrosion (tank linings, acid and alkali pipelines), high-temperature environments (high-temperature flue gas filtration), and long-term fixed large-span buildings (the ceilings of large exhibition halls).
- Scenarios where ETFE films are preferred
Inflatable film buildings (air-cushion stadiums, temporary exhibition halls), building facades or skylights (requiring light transmission and flexibility), and light anti-corrosion scenarios (rainwater recycling systems).