• Plastics Research

    Stuart McCutchen • 07/22/2020 at 20:46 • 0 comments

        In the past few weeks, the team has been getting familiar with the vast world of plastic welding. Understanding a field as extensive and technical as this has been a massive undertaking. Although we plan to continue researching and familiarizing ourselves with all angles of welding, it quickly became apparent how important material selection can be in the initial ideation phase. We realized as a team that whichever plastics we chose to pursue welding would ultimately determine the design and applications of our finished product. That being said, we searched high and low for the plastics that we considered to be the most useful and practical for the Field Ready organization.

    For us to create a product that will expand Field Ready’s toolbox, we took a step back and explored what they’ve tackled as an organization. Digging through dozens of their archived projects from years past showed the types of work that they like to focus on. Although Field Ready’s projects are wide-ranging, in general, they are quick to address the agricultural, architectural, and medical needs of developing countries. We wanted our material selection to reflect the mission of Field Ready by choosing plastics that could be as versatile as the organization itself.

    After extensive research, we decided that Polypropylene (PP) and Polyethylene (PE) would be the best plastics to center our design around. One of the major reasons behind this decision was both plastics are easy to weld and safe to weld if the proper precautions are in place. This is important to ensure our final product does not have a steep learning curve for the user(s), can increase efficiency of welding practices, and become an easy tool for FieldReady to teach to locals and workers in their Makerspaces.  We believe building a device that is compatible with PE will help reflect versatility in our plastic pursuits. PE comes in several different densities [low, medium, high, ultra high], all with their differing properties, allowing us to give Field Ready a tool with enough far-ranging applications to keep up with their constantly evolving workflow.

    Both PP and PE also have beneficial mechanical properties. PP is chemically resistant, has a high impact & tensile strength, and is the most dimensionally stable polyolefin. These are all important properties for an organization that largely works in remote areas and disaster-stricken areas. Field Ready’s prototyping material, infrastructure material, medical material, etc. will at some point be coming into contact with chemical substances, be subjected to high forces, and must be dimensionally accurate in certain situations. Selecting a plastic (such as PP) that can meet that criterion, and surpass it, is crucial. We found examples of PP being used in many relevant contexts including chemical, agricultural, and medical applications, confirming that we were going down the correct path.

    PE also shares similar properties. Besides its availability in different densities, a few properties that stand out are its high impact & abrasion resistance, high tensile strength, machinability, & low water absorption. These properties lend themselves to being applicable in a wide range of industries, such as agriculture and architecture.

    Despite all these positives about PP and PE, it is hard to deny that other plastics don’t also have these similar qualities to them. However, we were able to eliminate several plastics [PVC, PVDF, ECTFE, PFA, etc.] due to fumes alone. Provided adequate ventilation, most welds are okay, but even a few of the fumes from these plastics can go on to cause some serious complications if the proper personal protective equipment is not worn. We did not want to put these extra demands on the user and tried to find a way that would decrease as many regulations as possible (within limits). Furthermore, a lot of these additional plastics required a much higher temperature to reach their melting point and be considered...

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