Pursuing Better PVCs

Environmental Health Perspectives v.105, n.12,  Dec97

Many industries that manufacture products from polyvinyl chloride (PVC) are making new efforts to recycle the plastic, diverting millions of pounds of consumer waste from landfills and incinerators. Though the new initiatives are making PVC a more environmentally sound material, they fall short of the demands from some environmental groups who would like to see its production stopped completely.

PVC, which is used in products ranging from credit cards to garden hoses, is the second most popular plastic in the world. However, it has been recycled far less than other plastics such as polyethylene and polyethylene terephthalate. This causes concern among environmentalists and public health advocates, who say that both the manufacture of PVC and the incineration of the discarded plastic release dioxins into the atmosphere. Though there is some debate about the toxic effects of these chemicals, the NTP recently voted to label dioxins as "known human carcinogens," and there is evidence that they may also cause reproductive problems. Recycling PVC, on the other hand, may be a much cleaner process, and many industries are finding that recycling post-consumer plastic waste can be as cost-effective as making new PVC.

One of the biggest recyclers of PVC is Collins & Aikman, a manufacturer of floor covering in Dalton, Georgia. The company uses old carpeting that has PVC backing to make industrial flooring, highway sound barriers, marine bulkheads, and new carpet backing that is 75% post-consumer waste. In a normal year, over 3.5 billion pounds of carpet are landfilled at a price of $350 million. Collins & Aikman hopes that it can cut into this total by diverting over 75 million pounds to its Infinity Initiative recycling project. The Infinity Initiative gathers worn vinyl-backed carpet from the company's customer installation sites. The old carpet is chopped into small pieces and polyethylene pellets are added to it. The mixture is then simply melted and extruded into sheets of material suited for a variety of purposes.

A similar process is employed at Yemm & Heart Materials of Marquand, Missouri. To make its flexible surfacing material called Flexisurf, Yemm & Heart adds 10% polyester to the PVC that it has gathered from old pool covers, industrial roofing, and automobile dashboards. The addition of polyester gives the material rigidity and strength that rival the original PVC. Originally, Flexisurf was intended only to be used as industrial floor covering, but it has found its way into a variety of other products including computer mousepads, self-healing cutting surfaces, coasters and trivets, ladder treads, and tabletop surfaces. Yemm & Heart estimates it will recycle more than 34,000 pounds of plastic by the end of 1997.

A drawback to the processes employed by Collins & Aikman and Yemm & Heart is that once the PVC is mixed with other chemicals to form a new material, its chances of being recycled again are very slim. In effect, the PVC is used twice and then thrown away. However, some processes like the one employed by a consortium made up of IBM, Hydro Geon, and the Mann Organisation preserve the purity of the PVC so that it can be recycled over and over again. The process starts with the IBM facility in Greenock, Scotland, which collects used computer equipment containing PVC and sends it to the Mann Organisation, an electronics recycler in Ross-on-Wye, Scotland. Mann separates and granulates the materials and the screened granules are sent to Hydro Geon in Durham, England, which processes them into recycled PVC that is suitable for reuse by IBM. The consortium will recycle more than 400,000 pounds of PVC per year for use in IBM keyboard base covers. The recycled PVC meets all of IBM's standards for durability and resistance to scratching, color change, and fire.

source: http://ehpnet1.niehs.nih.gov/docs/1997/105-12/forum.html#pvc