Study Reveal Mechanical Properties of Flexible Film for Large Deflection
Polydimethylsiloxane (PDMS) is a flexible polymer characterized by good resilience, high chemical resistance and transmission. PDMS is widely used in nano-imprinting, self-assembling, and soft lithography as an elastic stamp to transfer nano- or micro-patterns. It also has been used as a flexible composite for various sensors due to its ability to respond readily to tensile, torsion, and compression.
Among these applications, many cases require flexible film to adapt the curved surface and perform larger camber deformation, such as wearable sensor attach to the joint and the flexible imprinting on the non-planar surfaces.
Therefore, the mechanical properties of PDMS film that matter most are relationship between input force and curvature of deformation, and the maximum received curvature that can be achieved before fracture, which have not been fully elucidated.
Researchers from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences studied the camber deformation of the PDMS film, the relationship of the deformation characteristics and maximum received curvature versus the properties of PDMS films, such as Young’s modulus and film thickness, has been investigated. The study was published in Optical Materials.
Firstly, the film samples were made by PDMS with different composition ratio of curing agent, and the Young’s modulus of each film was individually measured according to the Hooke’s law. Then, a vacuum chamber was set up to observe the camber deformation and the fracture at the maximum received curvature. The distribution of deformation and shear elastic strain of the PDMS film was calculated by finite element simulation.
The research results indicated that deformation was depended on the pressure, Young's modulus and film thickness, the maximum received curvature mainly affected by the film thickness, and the fracture shear strain was about 27~32% (mm-1) of film thickness.
This research focused on the camber deformation of the flexible film made by PDMS, and provided practical instructions for the further application of PDMS films.
Photo of the flexible film. (Image by SIAT)
Camber deformation and fracture process of the PDMS film (M10). (Image by SIAT)