This Special Report is an industry statement on the recyclability of phenolic materials. Its contents will define the role of phenolic suppliers and the Phenolic Division of The Society of the Plastics Industry, Inc. (SPI) on the topic of recycling, an increasingly important and viable option in the 1990s.

Four U.S.-based companies are currently involved in the recycling of phenolics: Rogers Corporation, based in Manchester, Connecticut; Plaslok Corporation, based in Buffalo, New York; Plastics Engineering Company, based in Sheboygan, Wisconsin; and Occidental Chemical (Durez). Consequently, this report will focus on the recycling activities of these companies, including the results of laboratory studies and pilot programs. It will also discuss an SPI- funded study by the Asphalt Institute Research Center on the use of ground phenolics in asphalt.

• ICI (Fiberite)
• Occidental Chemical (Durez)
• Plaslok Corporation
• Plastics Engineering Corporation (Plenco)
• Resinoid Engineering Corporation
• Rogers Corporation

The study's conclusions indicated that while behaving in a manner similar to a mineral filler, phenolics may improve (emphasis added) the engineering properties of an asphalt mixture. The study provided the producers of phenolic molding compounds with the information they needed to approach transportation departments with the concept of incorporating ground-cured phenolic as an aggregate modifier in asphalt.

Copies of the Asphalt Institute's report (catalog number AT-103) are available through SPI's Literature Sales at 1-800-541-0736.

Thermosetting phenolic composites are recyclable--by a different means than that of thermoplastics. Recycling studies indicate that molded phenolic (ground into a fine powder) can be successfully used in the raw material stream¹ (Figure 1) without compromising mechanical properties² (Figures 2-5).

Figure 1: Flow Chart for Recycling Roger's Phenolic

Figures 2 through 5 provide data collected on lab samples produced from Material A, a commercially available glass-reinforced phenolic material containing approximately 50% glass by weight. Recycle was added at levels of 4% to 12% by weight into a virgin raw material mix of the same formulation. The sizes of the ground recycle ranged from slightly larger than 80 mesh to smaller than 200 mesh.

Figure 2: Recycle Lab Results Flexural Strength at Room Temperature

The data indicates that the addition of up to 12% recycle did not significantly adversely affect the properties of the compound. The results show that the smaller particle sizes are desirable, but the larger particles are still acceptable.

Rogers is currently conducting pilot recycling programs with its customer base.

Figure 3:Recycle Lab Results Flexural Strength at 150°C

Figure 4:Recycle Lab Results Tensile Strength at Room Temperature

Figure 5:Recycle Lab Results Tensile Strength at 150°C

Note: The information provided by Rogers Corporation is not intended to and does not create any warranties, express or implied, including any warranty of merchantability or fitness for a particular purpose. Use of this material in your particular application may yield different results.

Plaslok Corporation of Buffalo, New York, a manufacturer of phenolic molding compounds, has also developed a recycling program to keep phenolic scrap out of landfills. The company collects runners, sprues, flash, and other forms of cured phenolic scrap from its customers via returnable containers; recycles this scrap material; and then recompounds it with virgin phenolics.

Despite the potential appeal of these recycling programs to the environmentally conscious, these efforts may be difficult to promote in states where landfill costs are low. But customers in states where landfill costs are high-such as New Jersey-have already used Plaslok's recycling program to reduce the amount of scrap being hauled to landfills.

According to Plaslok's Assistant General Manager Tacks Call, up to 15% of the amount of Plaslok material sold to a customer can be returned to the company for recycling. The product must be certified free of contamination, and Plaslok will pay the cost of return freight on minimum amounts, with certain restrictions.

Plaslok's recycling program has kept 500,000 pounds of phenolic scrap out of landfills during a period of just eight months. In addition to reducing landfill costs, participating customers have reported other benefits. The exact amount of scrap produced can be documented because the scrap must be gathered in one place and weighed for shipment, thus expanding the opportunities for improving the efficiency of scrap production.

Plastics Engineering Company (Plenco) has been an active participant in developing the SPI Phenolic Division's Recyling Blueprint. (See Figure 6.) Specifically, the company has stressed the source reduction of molded scrap phenolic as a key consideration in any recycling program. This program has been successful in helping molders and end users to significantly improve their yields in converting molding compound to finished product.

Plastics Engineering Company has been addressing the issue of grinding molded phenolic scrap from an engineering, logistics, and economics perspective. These ongoing investigations concentrate on optimizing the use of recycled molded scrap in particular products where performance levels can either be maintained or enhanced. Plenco Management has committed to fund a pilot program designed to further test the feasibility of the concept.

Laboratory studies are focusing on product performance of the molding compound. Testing is being done in accordance with UL standards to maintain UL yellow card listings.

Plastics Engineering Company has encouraged the investigation of other options available to molders for recycling on a localized basis, including the asphalt study discussed on page 1.

Source Reduction
The effort to minimize the amount of scrap initially generated, i.e., to minimize mold moldifications/formulation changes and the use of hollow sprues, hot cones, flat runners, etc.

Identification/Collection/End-Use Determination
1. Identification: the process of identifying the molded material, verifying that the molded material is phenolic and determining the filler/reinforcement type.
2. Collection: collecting it from the source, the molder.
3. End-Use Determination: determining the appropriate recycle stream.

Coarse Grind
The molded phenolic (sprues, runners, culls, parts without inserts, etc.) is ground into a 30-50 mesh material.

Sort & Clean
Any metal contamination is removed from the coarse material. If necessary, the material is cleaned with a solvent. Oil-contaminated material will be segregated. The goal is that this coarse material will not need cleaning, with all scrap remaining free of hydraulic fluid, oils, etc.

Fine Grind
The molded phenolic is ground into a 60-150 mesh material.

Recycle into Same Product
The fine or coarse material is added to the original formulation. The level of addition is determined by the compound supplier and the requirements of the end-use application.

Recycle into Lower Grade Product
The fine or coarse material is added to a different formulation, a low-cost material. The level of addition is determined by the compound supplier.

Recycle into Other Uses, i.e., Asphalt
The coarse material is used as an aggregate modifier in asphalt.

Thermal Treatment
The molded phenolic is subjected to heat to destroy organics and reduce volume.

Recycle via Energy Recovery
Generate steam or electric energy via combustion in industrial furnaces or boilers.

Recycle via Pyrolysis
Subject molded phenolic to low heat in order to extract chemical distillates for reprocessing and to recover basic chemical components.

in summary

The phenolic compounders and the SPI Phenolic Division are responding to the political and environmental realities of the 1990s. Outlets are now in place to handle the phenolic recycle stream. The message that phenolics are recyclable is being communicated to the media and industry, particularly among the automotive community. As "recyclable" becomes a material selection criterion, recycling outlets will ensure that phenolic continues to play a key role in composite material use.

For additional information on phenolic recycling, contact your phenolic compounder

Endnotes
^1,2Barbara A. Olson and Hendrick DeKeyser, Recycling Cured Phenolic Material, SAE International Congress and Exposition, 1992.