The Effect of Post-Processing Conditions on Injection Molded Part Performance
Category
Sciences and Technology
Department
Plastics Engineering Technology
Student Status
Undergraduate
Research Advisor
Dr. Jeanne Norton
Document Type
Event
Location
Student Center Ballroom
Start Date
10-4-2025 2:00 PM
End Date
10-4-2025 4:00 PM
Description
Plastics recycling is a growing environmental concern. When choosing recycled plastics for new parts, manufacturers prefer post-industrial material rather than post-consumer plastics because they are less contaminated, allowing for easier reprocessing into new products. Despite the advantages over post-consumer plastics, post-industrial plastic can experience temperature extremes. This investigation focuses on the effect of post-processing conditions on HDPE parts' thermal and mechanical properties. Materials used in this study were two different grades of HDPE material: Virgin HDPE and Crate HDPE. Each material was injection molded into test bars and conditioned after processing. Standard conditioning was one week at ambient temperature, pressure, and humidity. Two elevated temperatures were examined: 70C or 110℃ for 24 hours. Three reduced temperatures were also studied: 4℃ or - 25℃ for 24 hours, and ice bath quenching for one hour. Subsequently, we evaluated samples for thermal and mechanical properties. Mechanical properties included tensile and flexural modulus, ultimate elongation, and Izod impact strength. Tc and Tm were determined via DSC. Virgin HDPE had greater elongation than Crate HDPE under all conditions. Ice bath quenched Virgin HDPE showed greater tensile and flexural moduli. Both 70C and 110C Virgin HDPE had lower flexural moduli compared to other conditions and Crate HDPE. Crate HDPE had lower impact strength than Virgin HDPE overall. Virgin HDPE (70℃) and Crate HDPE (110C) showed improved notched impact strength. Tm was not affected in Virgin HDPE by conditioning, but Crate HDPE showed a 5 to 15% crystallization increase. Overall, post-processing of HDPE does affect important material properties.
The Effect of Post-Processing Conditions on Injection Molded Part Performance
Student Center Ballroom
Plastics recycling is a growing environmental concern. When choosing recycled plastics for new parts, manufacturers prefer post-industrial material rather than post-consumer plastics because they are less contaminated, allowing for easier reprocessing into new products. Despite the advantages over post-consumer plastics, post-industrial plastic can experience temperature extremes. This investigation focuses on the effect of post-processing conditions on HDPE parts' thermal and mechanical properties. Materials used in this study were two different grades of HDPE material: Virgin HDPE and Crate HDPE. Each material was injection molded into test bars and conditioned after processing. Standard conditioning was one week at ambient temperature, pressure, and humidity. Two elevated temperatures were examined: 70C or 110℃ for 24 hours. Three reduced temperatures were also studied: 4℃ or - 25℃ for 24 hours, and ice bath quenching for one hour. Subsequently, we evaluated samples for thermal and mechanical properties. Mechanical properties included tensile and flexural modulus, ultimate elongation, and Izod impact strength. Tc and Tm were determined via DSC. Virgin HDPE had greater elongation than Crate HDPE under all conditions. Ice bath quenched Virgin HDPE showed greater tensile and flexural moduli. Both 70C and 110C Virgin HDPE had lower flexural moduli compared to other conditions and Crate HDPE. Crate HDPE had lower impact strength than Virgin HDPE overall. Virgin HDPE (70℃) and Crate HDPE (110C) showed improved notched impact strength. Tm was not affected in Virgin HDPE by conditioning, but Crate HDPE showed a 5 to 15% crystallization increase. Overall, post-processing of HDPE does affect important material properties.
