Polyethylene terephthalate (PET) is widely used as a support layer for composite membranes because of its molecular structure, material properties, and performance characteristics. In this analysis, we will explore why PET is well suited for this application.
What is the molecular structure of PET film material?
1. PET is a thermoplastic polymer belonging to the polyester family, which is synthesized by the reaction of ethylene glycol (EG) and terephthalic acid (TPA) or its ester dimethyl terephthalate (DMT). The molecular structure of PET consists of alternating ester and aryl groups, which contribute to its strong mechanical properties and chemical stability.
2. The mechanical strength of PET, the aromatic rings in PET provide rigidity to the polymer chain, contributing to its high tensile strength and stiffness. This mechanical strength ensures that the support layer can withstand processing conditions and maintain its integrity during operation of the composite membrane.
3. PET has chemical stability, and the ester bond in PET is relatively stable to hydrolysis and other chemical reactions. This chemical stability is crucial for the support layer as it ensures that the membrane resists degradation or swelling in the presence of solvents, acids and bases.
What are the characteristics of PET film material?
PET has a variety of material properties that make it an ideal support layer for composite membranes.
1. Dimensional stability: PET has good dimensional stability, which means it maintains its shape and size under changing conditions such as temperature and humidity. This property is critical for the support layer as it ensures that the composite membrane maintains its performance and integrity over time.
2. Thermal stability: PET has a relatively high glass transition temperature (Tg) and melting temperature (Tm), which allows it to maintain its mechanical properties and dimensional stability at high temperatures. This thermal stability is essential for high temperature applications or when the membrane is exposed to temperature fluctuations during operation.
3. Porosity: PET can be made into a porous structure, which is a key feature of the support layer. The porosity allows efficient transport of permeate through the support layer, thereby minimizing the overall mass transfer resistance in the composite membrane.
What are the performance characteristics of PET film?
PET-based support layers offer several performance advantages in composite membranes.
1. PET is chemically compatible with a variety of film materials, such as polyamide, polyether and polyurethane. This compatibility allows the development of composite membranes with tailored properties for specific applications such as gas separation, water purification, and energy storage.
2. PET is an abundant and low-cost material, making it an attractive option for large-scale production of composite films. Using PET as a support layer helps reduce the overall cost of the membrane, making it more economically viable for a variety of applications.
3. As an environmentally friendly material, PET can be recycled and reused to reduce the impact on the environment. This feature is especially important given the growing focus on sustainability and the need to minimize waste in membrane technology.
In summary, the molecular structure, material properties and performance characteristics of PET make it an excellent choice for the support layer of composite membranes. Its mechanical strength, chemical stability, dimensional stability, thermal stability, porosity, compatibility with various membrane materials, low cost, and recyclability all contribute to its widespread use in this application.
Citation
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3.Zhang,S., Wu, H., & Huang, X. (2019). Fabrication of novel poly(ethyleneterephthalate) (PET) ultrafiltration membranes via a reactive blending method.Journal of Membrane Science, 583, 226-234. doi: 10.1016/j.memsci.2019.03.002.
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