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Green Chemistry and Design Composites Project

This web page serves as a clearinghouse for posting of findings from completed projects and for other information supporting or generated by this work.

MPCA staff thanks the U.S. Environmental Protection Agency's Pollution Prevention Program for its grant that supported this project.

Case Study: Styrene Free Resins in the Composites Industry - A Study of One Alternative

MPCA and the Minnesota Technical Assistance Program (MnTAP) conducted a composites grant project from October 1, 2011 through September 30, 2012. Activities for this composites project focused on evaluation of operational requirements and performance of a styrene free resin system for the Minnesota Fiber Reinforced Plastics (FRP) manufacturing sector. Renewed outreach to the sector built on work done earlier by MnTAP and MPCA and served to develop contacts and provide participants for this project. A pilot trial was conducted, samples were analyzed for physical property performance, and a webinar was held to present the results broadly to the industry and to help establish reasonable next steps for implementation of non-styrene resin materials in the composites industry.

Motivation

Environmental and health risks come from styrene in the resin that is released by evaporation during standard use conditions, resulting in employee exposure and releases of styrene to the environment. Project activities were set in place to allow FRP manufacturing firms to pilot the use of one styrene free resin for controlled end use application.  Educational events were planned to promote technology transfer and share findings.

Demonstration

A demonstration of the use and performance of the non-styrene based resin and the use of metering equipment to monitor resin application was planned as part of the original project. Due to the poor physical property results for the layup samples made with the NOVOC 8124 resin and Jushi glass during March/April trials, no demonstration event was conducted. Optimally a second trial should have been conducted with a more compatible fiberglass to ensure that reasonable physical property results could be achieved. After the results were presented to the host fiberglass manufacturer, they declined to hold an additional trial. The company could not afford to take operators and manufacturing space out of production if they could not be certain the product would work. Since the NOVOC 8124 resin did not produce parts that met performance expectations, it did not make sense to proceed with a demonstration that would put alternatives in an unfavorable position relative to the traditional styrene resins.

Pilot

A pilot of a styrene-free technology was conducted at a Minnesota fiberglass manufacturing firm on March 7, 2012 with a styrene based resin, Aropol 67301, compared with a polyester based resin containing no styrene, NOVOC 8124. Operators wore chemical exposure monitors during the styrene resin and non-styrene resin portions of the trial which were analyzed after the trial had concluded. Chemical monitoring badges used during the trial were 3M Type-3501 and were analyzed by Galson Laboratories. Two layer hand layup composite samples produced with each resin were analyzed for physical properties at COMTEC at Winona State University.

Observations during the trial:

  • Glass rich formulations appeared to cure and form to the molds better
  • Resin rich formulations had high exotherm temperatures
  • Resin did not easily or completely wet the fiberglass mat product used
  • Parts were slow to cure

Composite performance:

  • Physical properties of the non-styrene composite are 15-25% below those of the styrene resin
  • The poor physical property performance appears to be due to low composite density
  • The low density is a result of poor compatibility between the resin and the reinforcing fiberglass

Results from operator monitoring

Operator styrene exposure during the trial was down by 3-14 ppm (17-55%) for the two operators when they were using the NOVOC resin compared with the Aropol resin. The acetone exposure was up by 50-100 ppm (250-350%) during the NOVOC resin use. Results are shown in Table 1.

Table 1 – Operator Exposure Levels

Trial

Aropol 67301
Operator 1

Aropol 67301
Operator 2

NOVOC 8124
Operator 1

NOVOC 8124
Operator 2

Acetone

74

23

180

84

Styrene

27

17

13

14

The wide variation in the data indicates additional monitoring data would be required to statistically validate the change in operator styrene exposure when using the styrene free resins in a shop environment with both styrene and non-styrene containing resins in use.  

Conclusions

The lower density of the composite samples made with the non-styrene containing NOVOC 8124 resin and the lower strength performance on physical testing measurements is consistent with the high void ratio and apparent poor resin to glass adhesion observed in the scanning electron microscopy samples. Comparison with the physical properties of the NOVOC 8000 series resins on the company website suggests there is an opportunity to increase the physical property performance of the resin to be similar to those observed for the Aropol styrene based resin used as a comparison in this work.

Discussions with NOVOC Performance Resins, LLC about improving resin-to-glass adhesions revealed that the NOVOC resin typically does not show optimal performance with the Jushi fiberglass. Owens Corning fiberglass Advantex M710 and M720 was used to generate the samples for performance testing listed on the NOVOC website. The difference in performance is likely due to differences in proprietary glass binders and finishes used during the production of the fiberglass products as glass surface chemistries may be optimized for various resin compositions.

There are several options to increase the resin interaction with the glass surface. The first option is to use a glass with a surface treatment more compatible with the NOVOC resin. This would likely be a glass targeted to aliphatic type resin compositions. Another option could be to identify a suitable compatibilizing agent or coupling agent to improve the resin wetting to the glass surface, increasing reactive adhesion. To define the optimal performance of the NOVOC resin, it is recommended to layup a few pieces comparing performance between the NOVOC resin with Jushi fiberglass and with another suitable sample such as Owens Corning Advantex M720 fiberglass. Additional testing could be done with Aropol resin with both glass samples, if desired, to generate a full glass and resin matrix for performance comparison.

Discussions with academic researchers, industrial material providers, and FRP manufacturers after the webinar indicate continued interest in optimizing the performance of non-styrene resin products for the Minnesota FRP industry. MnTAP and MPCA will explore options for continuing an effort to define the range of performance opportunity using laboratory scoping effort followed by confirmation of performance in a manufacturing facility.

Webcast

Workshop on Green Chemistry Composites grant project

Sponsored by the Minnesota Pollution Control Agency in cooperation with the Minnesota Technical Assistance Program (MnTAP)

MnTAP served as the lead in a project to allow fiber reinforced plastics manufacturing firms to pilot the use of styrene free resin.

Findings from Composites Project using styrene-free resin

Webcast description

Fiber Reinforced Plastics (FRP) composites are used to make a wide variety of products including recreational boat hulls, electrical enclosures and heavy machinery bodies. The primary components of a FRP composite are chopped fiberglass, a polyester resin, and styrene as a volatile reactive crosslinking agent.

Environmental and health risks come with the use of styrene which is released by evaporation during open molding and spray operations. The work described here shares the results obtained from two projects developed to explore reducing air emissions through the use of styrene free resin systems.

  • Styrene Background
    • Project overview — Phyllis Strong, MPCA
    • Air quality requirements — Kim Grosenheider, MPCA
    • OSHA perspective — Peter Kuzj, Minnesota OSHA
  • Styrene in the Composities Industry — Laura Babcock, Director of MnTAP
  • Project results — Laura Babcock
    • Green Chemistry Demonsration Project
    • Alternative Resin Technical Assistance
    • Outcome and Opportunities
  • Questions

MPCA contact: Phyllis Strong, 651-757-2763.

 

Last modified on December 11, 2012 13:23

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