In late 1969, news from Louisville, Ky., shook the PVC world. The plant physician called a news conference at B.F. Goodrich Co.'s PVC factory there. Several workers had developed a rare form of liver cancer, he announced.
Each of the stricken workers had the job known as poly cleaner. After each batch, they scraped the vinyl chloride buildup off the walls of the polymerization reactor. The doctor announced that vinyl chloride monomer was a likely human carcinogen.
Goodrich started a project called Code Zero, staffed by about 130 engineers and scientists dedicated to solving the problem.
We could draft anybody we wanted any time, said Donald Witenhafer, then a member of the Code Zero team thanks to his background in PVC polymerization.
There was, of course, a sense of urgency. The management realized the people were dying and that took precedence over anything else. It was pretty obvious that the vinyl chloride was causing it, he said.
Environmental groups called for banning PVC, and governments began to take notice. The entire PVC industry was in a fight for survival.
The challenge was clear: Fully contain VCM in a closed system or forget about making vinyl.
Antone Vittone, president of BFG's chemical division, came up with Code Zero. Fred Krause, manager of PVC research and development at Goodrich, was in charge.
We probably had the best, at that time, R&D staff in the world on PVC, said Krause, who is retired. Witenhafer was one of about 15 key scientists working on the project.
PVC survived. Witenhafer was a co-inventor of several breakthroughs that helped make PVC manufacturing safer and gave it a future. The innovations were a way to remove residual VCM, and a water-based coating for the walls of the reactor tank, which eliminated the need for manual cleaning.
For his work, Witenhafer, 69, enters the Plastics Hall of Fame this week at NPE2009. But he stressed Code Zero was a team effort. When you worked on the Code Zero project, if you had an idea, you had a team. If you had a success, you had battalion, he said. It really had super-priority. You could walk in anywhere and say, 'This is a Code Zero project, stop what you're doing and work on this.' And people would do it.
Jack Koenig, Witenhafer's professor at Case Western Reserve University in Cleveland, nominated him for the Plastics Hall of Fame. Koenig himself went into the hall at the last NPE, in 2006 when he was nominated by Witenhafer.
At the time of Goodrich's Louisville announcement, Witenhafer was a scientist in the PVC polymerization research and development group at the company's technical center in Avon Lake, Ohio. He got exposed to plenty of VCM in the laboratory.
I thought I possibly was a dead man, he said.
A Cleveland native, Witenhafer got interested in science in high school. Initially, he wanted to study nuclear physics at CWRU, then known as Case Institute of Technology. He was a good student, but Case was tough. And then he found out he would need a Ph.D. to go into nuclear physics.
I thought to myself, 'Man there's no way I'm gonna survive nine years of this.' So I switched to chemical engineering.
After earning a bachelor's degree in 1962, he worked for a year in polyurethanes at Goodrich. Then he heard Eric Baer was starting a polymer science and engineering department at Case, and so Witenhafer enrolled in the first class, in 1963. Koenig was one of his teachers in graduate school.
Witenhafer got a master's degree, and then a doctorate, in polymer science. He went back to Goodrich, serving on a task force to improve rigid PVC, and then moved into the polymerization group.
The year before the vinyl chloride bombshell hit, Witenhafer became interested in the issue of VCM buildup in the reactors. He determined that eliminating the buildup could save the company $7 million a year.
Witenhafer said management wanted him to go back to the urethanes group, but relented after he insisted. That put him in the right place at the right time when the cancer announcement was made in Louisville when the focus became trying to get a closed reactor setup.
The first problem the Code Zero team had to solve was a daunting one. Does PVC depolymerize and release VCM during heating at processing temperatures say, in a pipe extruder? If that happened, every single extruder, injection press and blow molding machine would need special equipment to recover the monomer. The likely result: a death knell for PVC.
A review of all the technical literature turned up studies showing that some vinyl chloride was released during processing. Bad news. But it turned out that this was actually VCM that was left un-reacted during the resin-making process, Witenhafer said. They found that PVC does not depolymerize, but rather decomposes through a process that gives off small amounts of hydrochloric acid.
Get rid of any un-reacted VCM, and that problem was solved. Witenhafer said the revelation gave the team a shot of confidence.
We all said, you know, we got a shot. We have a real shot at being able to solve this problem. If we can make PVC that has no residual vinyl chloride in it, ship it out of the plant, we don't have to worry. People are not going to generate vinyl chloride in processing the PVC, Witenhafer said.
The other side of the coin was, we also had then to tighten up our plants so that we didn't release vinyl chloride mononer into the atmosphere.
The momentum was swinging.
We learned very early on that we could create a PVC that had no residual vinyl chloride in it, by using heat and vacuum to pull it out, he said. After several months, Code Zero concluded the best way was something called a steam stripping column.
Witenhafer described the inventions during an interview at his home in College Station, Texas.
After PVC resin gets polymerized, the resin slurry, resembling a mixture of sand and water, gets pumped into the steam stripping column. It trickles down, flowing through a series of trays, while hot steam comes upward. VCM and steam exit the top of the column. The resin slurry gets hit with a blast of fresh steam before it leaves the bottom of the column.
With about a two-minute average residence time in a steam stripping column, you can strip PVC resins down to below one part per million of residual vinyl chloride, Witenhafer said.
The recovered VCM goes into a plant recovery system and is re-used in polymerization.
Goodrich shared the steam stripping column design with other PVC manufacturers.
Witenhafer also was involved in research in the structure of the resin particles. The porosity must be uniformly distributed to make it easier to pull out the vinyl chloride.
The steam stripping column comes after polymerization. But was there a way to avoid VCM buildup in the reactor in the first place? The answer was to coat the reactor first.
Witenhafer had already been working on it.
Bear in mind, when I started this project, opening the vessel was absolutely no problem. Vinyl chloride was no problem. You could let out all you wanted. It wasn't an issue, he said. People had looked at solvents, but they required drying and had other drawbacks.
After the cancer news, the challenge was tougher. Not only did Code Zero members have to come up with a clean reactor coating, they needed a way to apply it without opening the reactor.
Witenhafer and a team came up with a water-based coating, which prevented buildup and did not need drying. Quick and easy.
At the Louisville plant, Code Zero had access to a working reactor. Witenhafer hit on blowing steam into the reactor to apply the coating.
Goodrich designed much larger, 16,500-gallon reactors equipped with the coating system. More than 700 batches can be polymerized before the vessel has to be opened.
After a long career at Goodrich, Witenhafer left in 1986 to become head of polymer research at S.C. Johnson & Son Inc. He worked there for five years, then became a consultant in Dublin, Ohio.
About two years ago, he moved with his wife, Carol, to College Station, home of Texas A&M University. He did not go to teach, but rather to be near their grandkids.
A long-time member of the Society of Plastics Engineers, Witenhafer chairs the SPE Polyolefins Conference in Houston. His 16-year term as an SPE council member expires at Antec this week, during NPE2009. He served on the executive committee four years.
Innovations by Goodrich's Code Zero team kept the VCM issue from turning into a firestorm. PVC has gone on to become an important material in medical products and construction applications.
But environmentalists, led by Greenpeace, continue to criticize PVC for things like lead, phthalates and chlorine. Witenhafer said it all stemmed from the long-resolved VCM issue.
My opinion is they're a bunch of spoilsports, he said. They smelled blood and when they couldn't get the blood because we did what we did, they [were] unhappy, and they don't want to give it up.