Date of Award
Master of Science in Chemistry (MSChem)
Dr. Jeanne Norton
Dr. Jody Neef
Controversy surrounds the use of plastic products, primarily due to their potentially negative impact on the environment at the end of their lifecycle. The most widely used plastics are manufactured from petrochemicals such as petroleum, coal or natural gas. Petrochemical plastics are not able to readily breakdown in the environment, which aggravates the existing pollution problems. Fortunately, there are eco-friendly alternatives to petrochemical-based plastics. Bioplastics may be derived from renewable sources, biodegradable, or both. Bio-based plastics are plastics that may be derived from renewable biomass sources including, but not limited to, vegetable oils, cornstarch, straw, woodchips, and food waste. They may be partially-derived or fully-derived from renewable sources. In addition to bio-based plastics, resin with post-consumer and post-industrial recycled content also offers a beneficial opportunity to reuse plastic in new products rather than manufacture more with virgin plastic. By taking advantage of these solutions, less petrochemical-based plastic will be manufactured, resulting in potential saving of finite resources, energy, and environmental waste. However, in order for companies to pursue the commercial use of bioplastics and wider use of recycled plastics, they need to ensure these eco-friendly materials still have the desired chemical, physical, and mechanical properties in commercial thermoplastic products.
In order for our industrial partner to convert to bioplastics for their parts, a suitable resin must first be identified. We will accomplish this goal first by comparing mechanical, thermal, and chemical properties of potentially viable bioplastics to that of the commercial petrochemical-based thermoplastics that are currently being used in manufacturing. This will provide useful information regarding the processing and properties of two control resins versus potential bioplastic resins. We will also gain more insight into the thermal properties of the resin prior to processing versus the injection molded part. Another commercial concern for product manufacturers is the ability to create plastic products with an appealing physical appearance. For that reason, we must also insure that potential bioplastics may be colored the same way as commercial thermoplastics, and not experience any discoloration in the product that may be inconsistent with the brand standard or unappealing to the consumer.
Using recycled plastic material, known as “regrind,” is both an environmentally friendly and cost-effective approach. However, post-consumer regrind (PCR) may negatively affect mechanical and thermal properties important to processing and end applications. Evaluation of varied levels of PCR will provide crucial information to our industrial partner regarding the processing and properties of PCR resins and the effect of increased regrind content on physical properties.
Thermal analysis will be done for all resins on differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC will erase any prior thermal history and allow us to evaluate glass transition temperature, melting temperature, and crystallinity of the resins. TGA will indicate upper use temperatures and demonstrate the temperature at which thermal degradation occurs. The best processing parameters will be determined for injection molding test bars. Molded parts will undergo Izod impact testing and tensile testing in order for us to evaluate the materials’ mechanical properties. Chemical resistance analysis will also be performed. This is essential to demonstrate the viability of a resin for use with household chemicals including pine-oil cleaner, hand soap, ammonia-containing window cleaner, and chlorine bleach. Lastly, a spectrodensitometer and a spectrophotometer will be used to determine any changes in color for eco-friendly samples versus control resins in samples that contain colorants.
Bicknell, Shelby, "Effect Of Post-Consumer Content and Bioplastic Incorporation on Polymeric Resin in Consumer Applications" (2020). Electronic Thesis Collection. 357.