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:

(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. (4) Conduct detailed mechanical and thermal characterization of reformulated composite materials. As a multidisciplinary team from Mechanical Engineering and Materials Science, our objective is 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).

Approach:

To recycle composite automobile components, they are first mechanically ground, or “chipped” such that glass fibers on the order of four centimeters, with some resin still attached, and matrix powder is produced. Our research is 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 recylate 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, that indicates that the onset of failure and the cracks propagate along the resin-resin interfaces. Some fiber pull-out 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 3-step modification process tested on resin-only systems, which will be adapted to the ground SMC.

As the resin-modification steps were completed, they were monitored using FTIR 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 1550 to 1680 cm-1, and the region from 3050 to 3700 cm-1 we were able to determine the effects of the chemical treatments.

The spectrum of the NaOH soak shows a reduction in the magnitude of the peak at 1725 cm-1 , and a new peak appears at 1578 cm-1 indicating the presence of a carboxylic acid salt. The band due to the carboxylic acid salt disappears in the iodomethane treated resin spectrum, and there is an increase in the peak at 1725 cm-1 indicating reformation of the polyester like structure.

After the MA soak there are three major things to note about the spectrum of the resin. First the height of the peak at 1725 cm-1 increases owing to the addition of the ester groups that are part of the maleic anhydride. Second, there is only a small broad peak left in the region from 3050 to 3700 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 1640 cm-1 after the treatment. Bands in this area are typical of double bonds in an ester.

Expected Results:

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 be now be carried out to create improved 2GC.

Relevant Websites:

http://ceer.alfred.edu Exit

Publications and Presentations:

Publications have been submitted on this subproject: View all 13 publications for this subprojectView all 34 publications for this center

Journal Articles:

Journal Articles have been submitted on this subproject: View all 3 journal articles for this subprojectView all 6 journal articles for this center

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

Progress and Final Reports:

  • 2002
  • Final Report

  • 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).
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    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
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