Grantees of the 2021 TechAccelR Grants
Additive that Prevents Surface Defects in PVC Films
Professor Milan Maric, Professor Richard Leask, both Chemical Engineering and Professor Jim Nicell, Civil Engineering
Executive Summary
Gas checks are visible fleck-shaped defects that occur on the surface of poly(vinyl chloride) (PVC) films during industrial calendering. Films containing these surface defects often do not meet minimum product specifications and therefore must be disposed of or recycled, resulting in increased cost and material waste. Currently, gas checks are controlled by keeping film gauge low and through trial-and-error modifications of processing parameters by calender operators. We found that a series of poly(caprolactone) (PCL)‐based compounds with diester linkers and alkyl chain cappers were all effective at preventing the formation of gas checks during calendering, with additive concentrations as low as 8 phr producing films with no gas checks.
High Temperature Te-Based Solder Alloys
Professor Mathieu Brochu and Dr. Sunyong Kwon, postdoctoral fellow, Materials Engineering
Executive Summary
High-temperature solders require solidus temperature at least 270 °C and the liquidus temperature at most 350 °C. Small solidification ranges are preferred to avoid solidification defects. The conventional high-temperature solders mainly comprise of Pb, which include Pb-5Sn, Pb-10Sn, Pb-5Ag, Pb-2Ag-8Sn, etc. Sn-based solder alloys are currently used for lead-free solders; but they suffer from high temperature properties due to their low solidus temperature (<260 °C). Alternatively, Bi-based solder alloys were invented (e.g. Bi-Ag), but their solidus temperature (262 °C) is still considered relatively low. For this reason, Pb-based alloys for HT solder applications have been exempted from the Restriction of Hazardous Substances (RoHS), but this exemption will not be permanent. The present invention provides four alloy compositions, whose eutectic temperatures ranging from 300 to 350 °C depending upon compositions. The alloys contain over 50 atomic percent Te, and an effective amount of Ag and Cu, optionally with Sn. Although Te is mildly toxic for humans, it is not hazardous for the environment. As such, Te is not listed in RoHS. Te has been used as an essential element for photovoltaic solar cell and thermoelectric materials. The technological limitation to be addressed is to develop lead-free, high solidus temperature, high service temperature alloys. The main advantage of the invention is the ideal eutectic temperatures (small solidification range) for high-temperature solder applications. In addition, Te is less reactive to oxygen than Bi and Sn, as such, oxidation during soldering can be reduced.
Accelerated Alloy Discovery Through Machine Learning: The KASSANDRA Method
Professor Mihriban O. Pekguleryuz and Dr. Luis Angel Villegas-Armenta, postdoctoral researcher, Materials Engineering
Executive Summary
Designing new materials is crucial to face the ever-increasing engineering challenges of the future. Particularly for metals, the light-alloy design is a process that involves great time and expenses to perfect a proposed material. This is traditionally done by incrementally adding elements to an alloy and testing various heat treatments until the desired properties are obtained, which involves substantial work at each iteration. The KASSANDRA method is a novel solution to design light alloys that relies on artificial intelligence to dramatically accelerate the design process. It is a flexible approach that can be applied to a wide range of challenges: mechanical resistance, corrosion resistance, ductility improvement, cost reduction and more. It has the potential to reduce the development process from years to weeks, reducing costs and giving companies a competitive edge over others traditional approaches.
Specifically, a CMOS imaging sensor is coupled with a sample microfluidic system. Samples swabbed from regions with high fluorescence will be placed on the microfluidic channels/wells on top of the CMOS sensor. Light will be generated during the ATP-mediated chemiluminescence reaction from the samples containing aerobic microorganisms, and the emitted light will be recorded and further analyzed for quantitatitation. We anticipate that a combined fluorescence and chemiluminescence approach will overall speed up the cleanliness assessment and increase the uptime for the processing facility or kitchens. Within the frame of this proposal, we will work on the adaptation and validation of the ATP chemiluminescence detection on a CMOS sensor and evaluate its use in conjunction with the CSI-D fluorescence device. Successful validation of this combined approach will lead to a robust tool for food safety inspection and quality control.
