Viscosity Approximation of PDMS Using Weibull Function

Abstract

The viscosity of a fluid is one of its basic physico-chemical properties. The modelling of this property as a function of temperature has been the subject of intensive studies. The knowledge of how viscosity and temperature variation are related is particularly important for applications that use the intrinsic friction of fluids to dissipate energy, for example viscous torsional vibration dampers using high viscosity poly(dimethylsiloxane) as a damping factor. This article presents a new method for approximating the dynamic viscosity of poly(dimethylsiloxane). It is based on the three-parameter Weibull function that far better reflects the relationship between viscosity and temperature compared with the models used so far. Accurate mapping of dynamic viscosity is vitally important from the point of view of the construction of viscous dampers, as it allows for accurate estimation of their efficiency in the energy dissipation process.

PDMS-polyimide transcutaneous blood gas collector with self-folding out-of-plane heater elements

“…Even though the intragroup folding angles varied, the left part of the figure indicates that the folding angle appeared to increase with lower temperature, i.e. higher surface tension and viscosity, as both increase with falling temperatures [13,14]. This is further supported by the right part of the figure where the PDMS brands are ordered by decreasing viscosity from left to right.…”

“…With the gas collector mounted on a neonate's skin, with an expected temperature of around 33 • C, and a target temperature of 43 • C, this means that the folded heater would only need about 50% of the time and 90% of the power to deliver the required heat compared to its flat counterpart. It should also be noted that the flat heater had a higher temperature on its backside than at 5, surface tensions modeled as described in [14] and viscosity as in [13]. its skin-facing frontside.…”

“…Given the general low thermal conductivity of PDMS, the time from mixing to casting differed with temperature-the first two mixes were cooled in a freezer and refrigerator, respectively, for 18 h. The 23 • C mix was cast directly after mixing, and the 38 • C mix was heated in an oven for 30 min. While the viscosities of the different brands were given by their respective data sheets, the temperature dependence of the viscosity was modeled using a Weibull function, as described in [13]. Similarly, the temperature dependence of the surface tension was modeled with the method described in [14].…”

Vitreous Substitutes from Bench to the Operating Room in a Translational Approach: Review and Future Endeavors in Vitreoretinal Surgery

“…The MW, which is determined by the length of the polymers, determines in turn the viscosity of the SiO, which is measured in centistokes (cSt). Increasing a SiO’s or PDMS’s polymer chain length means increasing the MW, which in turn increases the viscosity and therefore it corresponds to a higher cSt value [ 87 ]. The viscosities of the most commonly used PDMSs in vitreoretinal surgery today are 1.000 cSt (MW of 37 kDa) and 5.000 cSt (MW of 65 kDa) [ 80 , 88 ].…”

A facile method for fabricating microlens array with diverse morphologies at general thermal reflow conditions

“…The viscosity dependence relative to the mixing ratio and heating temperature of PDMS will have a certain impact on the experimental results. 26,27) After natural cooling, the cured PDMS layer can be peeled off from the substrate completely, and microlens array can be obtained [Fig. 1(f)].…”