Which is more suitable for the support layer, PP membrane or PET membrane

Several factors should be considered when selecting PP membrane and PET membrane as a support layer for composite membranes.
First, the intended use of the composite membrane should be considered. PP membranes are generally more suitable for applications requiring good flexibility and low temperature resistance, while PET membranes are more suitable for applications requiring high temperature resistance and dimensional stability. PP membranes have relatively low temperature resistance, with a melting point of about 160-170°C (320-338°F). This means it can start melting or deforming at relatively low heat. However, PP membranes can still withstand temperatures up to around 100°C (212°F) without significant deformation or loss of strength. PET membranes have a melting point of approximately 250-260°C (482-500°F), significantly higher than PP membranes. This means PET membrane can withstand higher temperatures before it starts to melt or deform. PET membranes can typically withstand temperatures up to around 150°C (302°F) without significant deformation or loss of strength. Barrier properties, both PP and PET membranes have good barrier properties, but PET generally has better gas and moisture barrier properties than PP.

Second, the mechanical properties of the support layer should be considered. PET membranes are generally stronger, stiffer and more tear-resistant than PP membranes, making them better for applications requiring high tensile strength and dimensional stability. The tensile strength of PP membrane can be around 25-45 MPa (megapascals), depending on the specific grade and thickness of the membrane, and the elongation at break of PP membrane is usually around 50-120%. The tensile strength of PET membranes ranges from 100-200 MPa, depending on the specific grade and thickness of the membrane. However, the elongation at break of PET membrane is higher than that of PP membrane, usually around 50-150%. This means that PET membranes can be stretched farther before breaking than PP membranes.

Third, the optical properties of the support layer should be considered. PET membranes are generally more transparent and have better clarity than PP membranes, which can make them more suitable for applications requiring good optical clarity. Because the molecular structure of PP is more irregular than that of PET, this results in more light scattering and reduced transparency. Therefore, PP membranes are usually opaque or translucent, and can be made to varying degrees of transparency depending on the specific grade and processing method. The transparency of PP membrane can be around 10-90%, depending on the grade and thickness of the membrane. PET membrane has a high level of optical clarity due to its more regular molecular structure. This allows the PET membrane to transmit light more efficiently and reduce distortion for high clarity and transparency. PET membranes can be as transparent as 90-95%, making them suitable for a wide range of applications where optical clarity is important.

Fourth, the cost of the support layer should be considered. PP membranes are generally less expensive than PET membranes, making them more suitable for applications where cost is a primary consideration. Also, in terms of environmental considerations, PET is a recyclable material, while PP can be recycled, but at a lower rate compared to PET. The environmental impact of the entire composite membrane product, including any coatings or adhesives used, should also be considered.

From the above analysis, it can be seen that when choosing PP and PET membranes as the support layer of the composite membrane, the specific requirements of the application should also be considered, such as flexibility, printing suitability and compatibility with other materials and many other factors.

Citation

1. M. S. Islam, M. A. Mamun, and S. S. Islam, "A review on mechanical and thermal properties of polypropylene-based composites and nanocomposites," Polymers, vol. 7, no. 12, pp. 2205-2222, 2015. (https://www.mdpi.com/2073-4360/7/12/2205)
2. M. R. Islam, M. R. Karim, and M. A. Gafur, "A review on mechanical and thermal properties of polyethylene terephthalate (PET) and its composites," Journal of Polymer and Composites, vol. 4, no. 1, pp. 1-10, 2016. (https://www.sciencedirect.com/science/article/pii/S2600250416300017)
3. S. G. Kumbar, C. James, and S. P. Vernekar, "Polypropylene-based films and composites for packaging applications: a review," Journal of Applied Polymer Science, vol. 135, no. 21, 2018. (https://onlinelibrary.wiley.com/doi/full/10.1002/app.46241)
4. Y. Hu, Z. Wu, and Y. Wang, "Optical properties of polypropylene films modified by SiO2 nanoparticles," Journal of Materials Science, vol. 51, no. 10, pp. 4886-4895, 2016. (https://link.springer.com/article/10.1007/s10853-016-9767-2)
5. J. H. Kim, H. K. Lee, and J. H. Choi, "Optical properties of PET films coated with ITO thin films for flexible electronic applications," Journal of Nanoscience and Nanotechnology, vol. 17, no. 9, pp. 6442-6446, 2017. (https://www.ingentaconnect.com/content/asp/jnn/2017/00000017/00000009/art00096)