Final Report: Recycling Glass-Reinforced Thermoset Polymer Composite Materials

EPA Grant Number: R828737C008
Subproject: this is subproject number 008 , established and managed by the Center Director under grant R830420
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Center for Environmental and Energy Research (CEER)
Center Director: Earl, David A.
Title: Recycling Glass-Reinforced Thermoset Polymer Composite Materials
Investigators: Mayes, Steven , DeRosa, Rebecca
Institution: Alfred University
EPA Project Officer: Klieforth, Barbara I
Project Period: September 1, 2001 through August 31, 2003
RFA: Targeted Research Center (2000) Recipients Lists
Research Category: Targeted Research

Objective:

The objectives of this research project were to: (1) investigate the interface chemistry between recycled and virgin constituent materials, including the use of coating agents, to provide the foundation for improving such materials and the resulting structural material; (2) investigate mechanical grinding parameters to identify and produce optimum constituent recyclate materials; (3) investigate material reformation technology to identify and produce optimum ratios for mixing virgin and recycled feedstock; and (4) conduct detailed mechanical and thermal characterization of reformulated composite materials.

As a multidisciplinary team from Mechanical Engineering and Materials Science, our goal was to conduct the basic research necessary to address the issue of removing significant amounts of thermoset composite materials from the solid waste stream terminating in our fast-disappearing landfills. Large-scale adoption of thermoset composites by the automobile industry has increased the urgency for developing a composite recycling infrastructure analogous to the one in place today for metals. Attempts by the composites community to recycle thermoset composites have essentially focused on innovative ways to grind up the waste composite material and use it as filler/reinforcement with a virgin resin matrix to form a new low-grade composite material.

Our research is focused on understanding and improving interfacial bonding between the recyclate and the virgin matrix material so that near original stiffness and strength is obtained from the second generation composites (2GC).

Summary/Accomplishments (Outputs/Outcomes):

To recycle composite automobile components, they are first mechanically ground, or “chipped” such that glass fibers on the order of 4 centimeters, with some resin still attached, and matrix powder is produced. Our research focused on combining the relatively high value glass fiber recyclate with virgin matrix to produce a 2GC that has nearly 100 percent of the strength and stiffness of the original material.

Our research to date has focused on three major studies: 2GC formulating and fabrication, failure mode analysis of the 2GC, and chemical modification of the recyclate portion of the 2GC.

Second, we used optical and electron microscopy to determine the failure mechanisms for the traditional recycled composite system. We have found that the failure mode for 2GC systems occurs between resin-resin interfaces. Crazing was found around chunks of resin pieces from recyclate, which indicates that the onset of failure and the cracks propagate along the resin-resin interfaces. Some fiber pullout is found at the fracture surface, but it is minimal compared to resin-resin debonding.

The microstructural data directed our efforts on cured polyester resin modification to enhance adhesion with virgin matrix polyester. We have not dealt with the fiber/resin interface because, at this time, it is a minor contributor to the failure of the 2GC. Finally, we identified a three-step modification process tested on resin-only systems, which will be adapted to the ground sheet molding compound (SMC).

As the resin-modification steps were completed, they were monitored using Fourier Transform Infrared (FTIR) spectroscopy techniques. The untreated resin has spectra typical of polyester with some water present on the surface. By monitoring the C=O peak, the region from 1,550 to 1,680 cm-1, and the region from 3,050 to 3,700 cm-1 we were able to determine the effects of the chemical treatments.

The spectrum of the sodium hydroxide (NaOH) soak shows a reduction in the magnitude of the peak at 1,725 cm-1, and a new peak appears at 1,578 cm-1 indicating the presence of a carboxylic acid salt. The band resulting from the carboxylic acid salt disappears in the iodomethane-treated resin spectrum, and there is an increase in the peak at 1,725 cm-1 indicating reformation of the polyester-like structure.

After the maleic anhydride (MA) soak, there are three major things to note about the spectrum of the resin. First the height of the peak at 1,725 cm-1 increases as a result of the addition of the ester groups that are part of the MA. Second, there is only a small broad peak left in the region from 3,050 to 3,700 cm-1 indicating that most of the OH groups are gone, having reacted with the MA. The third band of interest is the one that appears at 1,640 cm -1 after the treatment. Bands in this area are typical of double bonds in an ester.

It would appear that a carbon-carbon double bond, C=C, has been successfully added to the surface of the treated resin using this three-step process. These double bonds should react and form a covalent bond with a virgin resin during the crosslinking process. With successful introduction of double bonds to the surface, treatment of the SMC recyclate can now be carried out to create improved 2GC.

We have submitted a summary of our work through summer 2002 to Silvio de Andrade, Editor of Revista do Plástico Reforçado., who is writing a series of articles on composite recycling. He requested the summary for publication in a Brazilian trade journal.


Journal Articles on this Report : 3 Displayed | Download in RIS Format

Other subproject views: All 13 publications 3 publications in selected types All 3 journal articles
Other center views: All 34 publications 8 publications in selected types All 6 journal articles
Type Citation Sub Project Document Sources
Journal Article DeRosa R, Telfeyan E, Gaustad G, Mayes S. Strength and microscopic investigation of unsaturated polyester BMC reinforced with SMC-recyclate. Journal of Thermoplastic Composite Materials 2005;18(4):333-349. R828737C008 (Final)
  • Abstract: Journal of Thermoplastic Composite Materials
    Exit
  • Journal Article DeRosa R, Gaustad G, Telfeyan E, Mayes JS. Microscopical evaluation of recycled glass-reinforced polymer matrix composites. Microscopy and Analysis 2004;18(5):9-11. R828737C008 (Final)
    R830420 (Final)
    X832541 (2007)
    X832541 (Final)
  • Abstract: Microscopy and Analysis
    Exit
  • Journal Article DeRosa R, Telfeyan E, Mayes JS. Current state of recycling sheet molding compounds and related materials. Journal of Thermoplastic Composite Materials 2005;18(3):219-240. R828737C008 (Final)
    R830420 (Final)
  • Abstract: SAGE Journals Online
    Exit
  • Supplemental Keywords:

    thermoset composite, composite recycling, glass fiber recyclate, formulating and fabrication, failure mode analysis, chemical modification, FTIR, second generation composite,, RFA, Scientific Discipline, Sustainable Industry/Business, POLLUTION PREVENTION, waste reduction, Sustainable Environment, Technology for Sustainable Environment, Chemistry and Materials Science, automotive supply chain, polymer composite materials, waste minimization, waste recycling, automotive industry, environmental sustainability, automotive components, alternative materials, recycled composite automotive components, recycling, pollution prevention design

    Relevant Websites:

    http://ceer.alfred.edu Exit

    Progress and Final Reports:

    Original Abstract
  • 2002

  • Main Center Abstract and Reports:

    R830420    Center for Environmental and Energy Research (CEER)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R828737C001 Environmental Impact of Fuel Cell Power Generation Systems
    R828737C002 Regional Economic and Material Flows
    R828737C003 Visualizing Growth and Sustainability of Water Resources
    R828737C004 Vibratory Residual Stress Relief and Modifications in Metals to Conserve Resources and Prevent Pollution
    R828737C005 Detecting and Quantifying the Evolution of Hazardous Air Pollutants Produced During High Temperature Manufacturing: A Focus on Batching of Nitrate Containing Glasses
    R828737C006 Sulfate and Nitrate Dynamics in the Canacadea Watershed
    R828737C007 Variations in Subsurface Denitrifying and Sulfate-Reducing Microbial Populations as a Result of Acid Precipitation
    R828737C008 Recycling Glass-Reinforced Thermoset Polymer Composite Materials
    R828737C009 Correlating Clay Mineralogy with Performance: Reducing Manufacturing Waste Through Improved Understanding
    R830420C001 Accelerated Hydrogen Diffusion Through Glass Microspheres: An Enabling Technology for a Hydrogen Economy
    R830420C002 Utilization of Paper Mill Waste in Ceramic Products
    R830420C003 Development of Passive Humidity-Control Materials
    R830420C004 Microarray System for Contaminated Water Analysis
    R830420C005 Material and Environmental Sustainability in Ceramic Processing
    R830420C006 Interaction of Sealing Glasses with Metallic Interconnects in Solid Oxide and Polymer Fuel Cells
    R830420C007 Preparation of Ceramic Glaze Waste for Recycling using Froth Flotation
    R830420C008 Elimination of Lead from Ceramic Glazes by Refractive Index Tailoring
    R830420C010 Nanostructured C6B: A Novel Boron Rich Carbon for H2 Storage