Grantee Research Project Results
Final Report: Nanoclay Reinforced Recycled HDPE to Replace PVC and PE Water Pipe Materials
EPA Grant Number: SU840159Title: Nanoclay Reinforced Recycled HDPE to Replace PVC and PE Water Pipe Materials
Investigators: Na, Sukjoon , Youn, Sungmin
Institution: Marshall University
EPA Project Officer: Page, Angela
Phase: I
Project Period: December 1, 2020 through November 30, 2021 (Extended to November 30, 2022)
Project Amount: $24,946
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2020) RFA Text | Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Chemical Safety
Objective:
High density polyethylene (HDPE) is one of the most widely used plastics in household products and engineering applications due to its good mechanical properties, chemical and corrosion resistance, low cost, and ease of processing. However, with the increased use of HDPE, the concerns about accumulated plastic waste have grown due to its permanence in the environment. Although the utilization of recycled HDPE can offer many benefits for plastic waste management, recycled HDPE materials are prone to possessing inferior properties compared to pristine counterparts. Thus, recycled plastics are not recommended for engineering applications, particularly in critical infrastructures.
To improve the sustainability of HDPE and suggest a solution to those arisen concerns, this EPA P3 Phase I project aims to evaluate the applicability of nanoclay reinforced recycled high density polyethylene (HDPE) as a potential water pipe material that can be applied in aggressive chemical environments. Polymer nanoclay composites have continuously received great attention as an alternative to a new class of pipe materials due to their potentially enhanced material properties. Several remarkable improvements in the properties of nanoclay composites have been reported. For example, incorporating a small amount of nanoclay into thermoplastic polymers significantly increases tensile strength and modulus. In addition, impermeable and dispersed nanoclay in a polymer matrix increases the length of the diffusing gas path, leading to an increase in barrier properties.
Based on those reported improvements, we assume that nanoclay may also enhance the resistance to chemical degradation and failure under severe chemical conditions. Our current hypotheses for the project are that (1) incorporating nanoclay into recycled HDPE will enhance the chemical resistance of composites, and thus allow the use of recycled HDPE for water pipe systems; (2) chemical resistance of degradation behavior will vary with the compositions of nanoclay and recycled HDPE contents; (3) ultimately, nanoclay reinforced recycled HDPE will be a new group of sustainable materials that utilized recycled plastics and environmental-friendly nanoclay.
Summary/Accomplishments (Outputs/Outcomes):
Under the support of the EPA P3 program, the PI and co-PI could develop a new material lab that allows the production of 3D-printed recycled HDPE blends/nanoclay composites from raw plastic resin. The test materials were prepared by the use of a lab-scale single-screw extruder, and test specimens were manufactured by the use of a 3D printer. To overcome the known challenges that prevent HDPE from 3D printing, parametric studies were conducted to find the optimal extruding and printing conditions. The fracture behavior of test materials was characterized by the EWF concept which is popularly used for ductile polymer materials. The results indicate that blending recycled HDPE with the pristine one decreased the fracture toughness of HDPE. The test materials degraded under chemical exposure for 30 days show lower fracture toughness values. In addition, the same materials but blended with various nanoclay contents were tested to evaluate the effect of nanoclay on the chemical degradation resistance. The results imply that the addition of nanoclay to recycled HDPE blends decreases the fracture toughness; however, it may also help to decrease the rate of chemical degradation. It should be noted that the test results possess relatively low R 2 values implying low reliability. A description of achievements over the entire period of funding is summarized below.
- Parametric studies of the optimal parameters that allow extruding pristine and recycled HDPE/nanoclay composite filaments from the raw pellets.
- Parametric studies of the optimal parameters that allow 3D printing pristine and recycled HDPE/nanoclay composite specimens from the filaments.
- Development of new analysis that allows applying the EWF concept to 3-D printed recycled HDPE blends
- Evaluation of applicabilities and challenges of the EWF concept test for the 3D-printed recycled HDPE blends/nanoclay composites
- Engagement of students in the funded EPA P3 research. For the past two years, one graduate and four undergraduate students were engaged and developed their research experience.
- Publishment of research outcomes in conferences and a journal. Our research team participated in three conferences: (1) 2021 P3 Expo, (2) The 2022 World Congress on Advances in Civil, Environmental, & Materials Research (ACEM22), and (3) 20th Annual Undergraduate Research Day at the Capitol, WV. In addition, we published one abstract in the conference proceeding of ACEM22 and submitted one research article to the journal of Geomechanics and Engineering (GAE).
- Development of new partnerships with industries. We developed new partnerships with industries for the research project. Braskem America and Envision Plastics donated various HDPE resins and recycled HDPE pellets, respectively.
Conclusions:
In summary, this research project focused on the applicability of nanoclay-reinforced recycled HDPE as an alternative to conventional plastic water pipe materials in an aggressive chemical environment. Also, the project studied the technical feasibility of the materials for the use of the 3-D printing technique. The project utilized recycled plastic materials to mitigate concerns regarding accumulated solid wastes in the environment. The results show that nanoclay may have the potential to resist chemical degradation of the materials. However, due to the intrinsic material and structural issues derived from HDPE and 3-D printing techniques, most test results could not provide reliable data. Further research should be conducted to conclude the effect of nanoclay on the fracture characterization of recycled HDPE blends.
Journal Articles:
No journal articles submitted with this report: View all 3 publications for this projectSupplemental Keywords:
Recycled high-density polyethylene (HDPE), essential work of fracture concept (EWF), filament, 3-D printingRelevant Websites:
2021 P3 Expo - Nanoclay Reinforced Recycled HDPE to Replace PVC and PE Water Pipe Materials
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.