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Executive of the Year: Knowledge of business, industry sets William Stockwell apart
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PHILADELPHIA—When Jerry Krummel attended a trade show meeting with Stockwell Elastomerics Inc., he expected to discuss silicone supply in the upcoming year. What the sales director for...
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PHILADELPHIA—William Stockwell's sense and hands-on attitude are a few of the reasons why he was chosen as the Rubber & Plastics News 2018 Rubber Industry Executive of the Year. PHILADELPHIA—William Stockwell's sense and hands-on attitude are a few of the reasons why he was chosen as the Rubber & Plastics News 2018 Rubber Industry Executive of the Year. $PHILADELPHIA—William Stockwell's sense and hands-on attitude are a few of the reasons why he was chosen as the Rubber & Plastics News 2018 Rubber Industry Executive of the Year.
Cooper Tire, Sailun to form joint venture, build truck, bus tire plant
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FINDLAY, Ohio—Cooper Tire & Rubber Co. and Sailun Vietnam Co. Ltd. have agreed to set up a joint venture to oversee the construction of a radial truck/bus tire plant in Vietnam rated at ...
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FINDLAY, OhioŚCooper Tire and Sailun Vietnam have agreed to set up a joint venture to oversee the construction of a radial truck and bus tire plant in Vietnam rated at more than 2 million units annually. FINDLAY, OhioŚCooper Tire and Sailun Vietnam have agreed to set up a joint venture to oversee the construction of a radial truck and bus tire plant in Vietnam rated at more than 2 million units annually. $FINDLAY, OhioŚCooper Tire and Sailun Vietnam have agreed to set up a joint venture to oversee the construction of a radial truck and bus tire plant in Vietnam rated at more than 2 million units annually.
Nokian opens North American headquarters in Nashville
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NASHVILLE, Tenn.—Nokian Tyres P.L.C. has opened its North American headquarters office in Nashville, housing the company's sales, customer service, IT, logistics and marketing teams. As...
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NASHVILLE, Tenn.—Nokian has opened its North American headquarters office in Nashville, housing the company's sales, customer service, IT, logistics and marketing teams. NASHVILLE, Tenn.—Nokian has opened its North American headquarters office in Nashville, housing the company's sales, customer service, IT, logistics and marketing teams. $NASHVILLE, Tenn.—Nokian has opened its North American headquarters office in Nashville, housing the company's sales, customer service, IT, logistics and marketing teams.
NIBA president looks to keep the course
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PHOENIX—Brian Schachner, NIBA's new president, wants to help the association stay steady on a path of growth established by prior leadership. "My goal is mainly to maintain the direction...
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PHOENIX—Brian Schachner, NIBA's new president, wants to help the association stay steady on a path of growth established by prior leadership. PHOENIX—Brian Schachner, NIBA's new president, wants to help the association stay steady on a path of growth established by prior leadership. $ PHOENIX—Brian Schachner, NIBA's new president, wants to help the association stay steady on a path of growth established by prior leadership.
Executive of the Year: Philadelphia group seeks to provide road for ex-offenders
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Often times, the people who need a second chance don't get it. Fortunately, William Stockwell believes in second chances. The president of Philadelphia-based Stockwell Elastomerics Inc....
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Often times, the people who need a second chance don't get it. Fortunately, William Stockwell believes in second chances. Often times, the people who need a second chance don't get it. Fortunately, William Stockwell believes in second chances. $Often times, the people who need a second chance don't get it. Fortunately, William Stockwell believes in second chances.
Executive of the Year: William Stockwell makes lasting impact on his family's company, employees
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William Stockwell always wanted to follow his own path. Oddly enough, embracing the same family legacy he initially felt would prevent him from forging his own identity has allowed him to do just...
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William Stockwell always wanted to follow his own path. Oddly enough, embracing the same family legacy he initially felt would prevent him from forging his own identity has allowed him to do just that. William Stockwell always wanted to follow his own path. Oddly enough, embracing the same family legacy he initially felt would prevent him from forging his own identity has allowed him to do just that. $ William Stockwell always wanted to follow his own path. Oddly enough, embracing the same family legacy he initially felt would prevent him from forging his own identity has allowed him to do just that.
Editorial: Trade dispute over rubber bands has big implications
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Much of the talk regarding international trade wars, tariffs and duties revolves around what impact those activities will have on the automobile industry and, closer to our readership, the tire...
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Much of the talk regarding international trade wars, tariffs and duties revolves around what impact those activities will have on the automobile industry and, closer to our readership, the tire sector. Much of the talk regarding international trade wars, tariffs and duties revolves around what impact those activities will have on the automobile industry and, closer to our readership, the tire sector. $ Much of the talk regarding international trade wars, tariffs and duties revolves around what impact those activities will have on the automobile industry and, closer to our readership, the tire sector.
Auto sales volume dips as cars sputter, still on pace for 17 million sold this year
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U.S. light-vehicle sales slipped 0.5 percent in November as robust fleet shipments by some auto makers failed to offset slumping demand for passenger cars. But the seasonally adjusted annualized...
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U.S. light-vehicle sales slipped 0.5 percent in November as robust fleet shipments by some auto makers failed to offset slumping demand for passenger cars. U.S. light-vehicle sales slipped 0.5 percent in November as robust fleet shipments by some auto makers failed to offset slumping demand for passenger cars. $U.S. light-vehicle sales slipped 0.5 percent in November as robust fleet shipments by some auto makers failed to offset slumping demand for passenger cars.
Mary Barra pressed by Ohio senators to keep GM's Lordstown plant open
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WASHINGTON—Ohio's Sens. Sherrod Brown and Rob Portman urged General Motors CEO Mary Barra to accelerate contract talks with union officials and decisions on where to build new products so...
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WASHINGTON—Ohio's Sens. Sherrod Brown and Rob Portman urged General Motors CEO Mary Barra to accelerate contract talks with union officials and decisions on where to build new products so the state's Lordstown plant can continue operating. WASHINGTON—Ohio's Sens. Sherrod Brown and Rob Portman urged General Motors CEO Mary Barra to accelerate contract talks with union officials and decisions on where to build new products so the state's Lordstown plant can continue operating. $WASHINGTON—Ohio's Sens. Sherrod Brown and Rob Portman urged General Motors CEO Mary Barra to accelerate contract talks with union officials and decisions on where to build new products so the state's Lordstown plant can continue operating.
Wacky World of Rubber: Nectar bets on science, humor in new ad campaign
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Nectar Sleep gets it. Science sells. Late last month, Nectar launched a YouTube ad featuring Mayim Bialik, who probably is best known for her portrayal of neurobiologist Amy Farrah Fowler in the...
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Nectar Sleep gets it. Science sells. That's why the company launched a new ad featuring actress and real-life scientist Mayim Bialik, best known for her portrayal of neurobiologist Amy Farrah Fowler in the CBS sitcom "The Big Bang Theory." Nectar Sleep gets it. Science sells. That's why the company launched a new ad featuring actress and real-life scientist Mayim Bialik, best known for her portrayal of neurobiologist Amy Farrah Fowler in the CBS sitcom "The Big Bang Theory." $Nectar Sleep gets it. Science sells. That's why the company launched a new ad featuring actress and real-life scientist Mayim Bialik, best known for her portrayal of neurobiologist Amy Farrah Fowler in the CBS sitcom "The Big Bang Theory."
Digital Edition
Digital Edition
Published on January 1, 2005

Chain Transfer in Polymerizations--Molecular Weight Control and More

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Date Published January 1, 2005
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This Report has been authored by:Vijay R. Srinivas at Arkema Inc.

Control of molecular size and molecular weight distribution is necessary so that the resulting polymers have good processability and have specific properties required for their intended applications. Chain transfer is the process of regulating and controlling molecular weight. Some experts consider this process of chain transfer as the fourth process in polymerizations, along with initiation, propagation and termination. Chain transfer was first observed in radical polymerizations but occurs in ionic polymerizations also. Alkyl thiols (Mercaptans) have been recognized to be one of the most efficient chain transfer agents in polymerizations that produce polystyrene, styrene-butadiene rubber, ABS terpolymers, polymethacrylates (e.g. PMMA), polyacrylates and other vinyl-type of polymers. Chain transfer can also be used to make low molecular weight polymers (telomers), introduce branching and cross-linking. t-Dodecyl mercaptan (TDM) and n-dodecyl mercaptan (NDM) are examples of the two most common chain transfer agents. In many polymerizations, TDM is the choice due to the fact that its Chain Transfer Constant (CT) is an aggregate of different numbers since it is a mixture of several tertiary mercaptans of carbon number C10 to C13. NDM, on the other hand, is a pure C12 mercaptan with a higher CT, thus giving a narrower molecular weight distribution. Mechanism of the various reactions involved in chain transfer will be discussed. Some strategies involving the use of chain transfer agents-mercaptans in particular, for improving thermal stability of the polymers, increasing branching, providing enhanced cross-linking, will also be discussed.

 
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