Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Supervisor

Dr. Joshua M. Pearce

Abstract

This work aims to make thermoforming more accessible to incentivize prosumer participation in localized recycling by providing a combined open source 12” x 12” compression molding and vacuum forming tool. The hardware was validated across a series of applications, each providing a different economic or functional incentive. For prosumers, this included compression forming 1/4" recycled polycarbonate and HDPE sheets, 20-gauge vacuum sheets, and vacuum formed applications with savings of up to 99.9% over commercial sources for 100-part batch production case studies. For researchers and commercial interest, the hardware was used to produce ASTM D695 standard samples of 1:1 silica sand and polycarbonate. The resulting composite was mechanically tested to yield a 71MPa average compressive strength competitive with high performance concrete. The hardware presented in this study provides users with the resources to manage local recycling for product development, customization and research using traditional thermoforming methods in a reduced footprint.

Summary for Lay Audience

Commercial recycling is responsible for directing 50% of thermoplastic waste to landfill with even more being mismanaged. This handling of plastic waste contributes both to environmental degradation and the rapid waste of a nonrenewable resource. To combat this, localized distributed recycling in which consumers contribute to the handling and recycling of their own waste has become increasingly appealing and effective. This approach is most effective amongst community members interested in both consuming and producing (prosumers) for personal and professional use. Therefore, to promote localized recycling, a prosumer target audience requires accessible hardware that can expand their ability to utilize local plastic waste and provides applications that incentivize the adoption of this hardware.

This work presents a hardware design that integrates two complementary thermoforming methods into the same machine footprint including compression molding and vacuum forming to broaden the capabilities of prosumers to handle thermoplastics. For 68.6% the cost of a commercial 11” x 9” Formech 300DT vacuum former, the hardware developed in this study offers increased functionality and compatibility with recycled regrind at a reduced cost. This hardware uses waste plastic regrind as the charge for compression molding to form stock sheets of varying thicknesses for any 2.5-D application Through a simple tooling changeover routine, the functionality of the system can be converted from compression molding to vacuum forming.

To define the economic and functional incentive of this equipment to a prosumer, the hardware was used to form 1/4" recycled polycarbonate and HDPE sheets and 20-gauge HDPE vacuum sheets. The vacuum forming sheets were used with a series of 3-D printed molds to investigate the economic incentive of batch production using the vacuum former. The compression molder was used to investigate the incentive of using this hardware for producing standard research sample for mechanical testing to quantify material properties. A case study using the compression molder to develop a 1:1 sand and polycarbonate composite was conducted, and the results yielded a 71MPa average compressive strength comparable to high performance concrete. Therefore, this hardware offers economic and functional incentive to prosumers and researchers and encourages the adoption of localized recycling.

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