Experimental study on mechanical performance of polydimethylsiloxane (PDMS) at various temperatures

The Abrasive Jet Machining (AJM) of Polydimethylsiloxane (PDMS) is very slow or even impossible at room temperature due to its ability to absorb the energy of the impacting particles. Cryogenic Abrasive Jet Micro-machining (CAJM) can enhance the material removal rate, and accordingly, the mechanical performance of PDMS can critically affect its processability. The goal of this study is to investigate the physical properties of PDMS at different temperatures. For this, PDMS samples were fabricated for compressive, hardness, X-ray Diffraction and linear expansion coefficient testing, according to GB standards. The results showed the following values: compressive modulus of 17.31-1160.1 MPa; ultimate compressive strength of 160.25-224.50 MPa; hardness of 43 Sh(A)-90.67 Sh(D), coefficient of thermal expansion (CTE) of 247E-06 1/K (103 K to RT, 3 K/min) at different temperatures, over the range of room temperature at, RT = 298 to 123 K. Moreover, the influence of temperature on the compressive fraction surface microstructure was analyzed with scanning electron microscopy (SEM). The results showed that with the decrease of temperature, the failure mode of PDMS material changed from ductile to brittle, and the material exhibited evident brittle characteristics until 123 K.