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Auto industry grapples with multiple forces shaking up business
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DETROIT—It's an exciting time to be in the automotive industry, but that also means there's plenty of uncertainty to go around.With trade relations going under the knife, emerging vehicle...
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DETROIT—It's an exciting time to be in the automotive industry, but that also means there's plenty of uncertainty to go around. DETROIT—It's an exciting time to be in the automotive industry, but that also means there's plenty of uncertainty to go around. $DETROIT—It's an exciting time to be in the automotive industry, but that also means there's plenty of uncertainty to go around.
Bridgestone to expand Tennessee truck tire plant
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MORRISON, Tenn.—Bridgestone Americas Inc. is planning to break ground later this year on an expansion that will increase capacity at its Warren County, Tenn., truck/bus tire plant by about 8 ...
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MORRISON, Tenn.—Bridgestone Americas is planning to break ground later this year on an expansion that will increase capacity at its Warren County, Tenn., truck/bus tire plant by about 8 percent. MORRISON, Tenn.—Bridgestone Americas is planning to break ground later this year on an expansion that will increase capacity at its Warren County, Tenn., truck/bus tire plant by about 8 percent. $MORRISON, Tenn.—Bridgestone Americas is planning to break ground later this year on an expansion that will increase capacity at its Warren County, Tenn., truck/bus tire plant by about 8 percent.
Coker Tire CEO Wade Kawasaki, investor group take ownership of company
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CHATTANOOGA, Tenn.—A group of Coker Group executives, led by President and CEO Wade Kawasaki, has partnered with Irving Place Capital to acquire the supplier of collector car and motorcycle...
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CHATTANOOGA, Tenn.—A group of Coker Group executives, led by President and CEO Wade Kawasaki, has partnered with Irving Place Capital to acquire the supplier of collector car and motorcycle tires and wheels. CHATTANOOGA, Tenn.—A group of Coker Group executives, led by President and CEO Wade Kawasaki, has partnered with Irving Place Capital to acquire the supplier of collector car and motorcycle tires and wheels. $CHATTANOOGA, Tenn.—A group of Coker Group executives, led by President and CEO Wade Kawasaki, has partnered with Irving Place Capital to acquire the supplier of collector car and motorcycle tires and wheels.
New technology may separate ethylene from ethane more efficiently
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SAN ANTONIO—Researchers are finding unusual ways to cut the production cost for ethylene. Cracking naphtha from crude oil is an important ethylene production route. However, this reaction...
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SAN ANTONIO—Researchers are finding unusual ways to cut the production cost for ethylene. SAN ANTONIO—Researchers are finding unusual ways to cut the production cost for ethylene. $SAN ANTONIO—Researchers are finding unusual ways to cut the production cost for ethylene.
Photos: Semperit expands Czech hose plant
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VIENNA—The Semperit Group invested $30.4 million in an expansion at the Semperflex Optimit s.r.o. location in Odry, Czech Republic. The expansion increases production capacity to 109...
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VIENNA—The Semperit Group invested $30.4 million in an expansion at the Semperflex Optimit location in Odry, Czech Republic. VIENNA—The Semperit Group invested $30.4 million in an expansion at the Semperflex Optimit location in Odry, Czech Republic. $VIENNA—The Semperit Group invested $30.4 million in an expansion at the Semperflex Optimit location in Odry, Czech Republic.
Toyoda Gosei expands in China with acquisition of Hubei Rock
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KIYOSU, Japan—Toyoda Gosei Co. Ltd. is purchasing a majority stake in Hubei Rock Rubber and Seal Technology Co. Ltd. to strengthen its automotive parts business in China. The deal is...
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KIYOSU, Japan—Toyoda Gosei is purchasing a majority stake in Hubei Rock Rubber and Seal Technology to strengthen its automotive parts business in China. KIYOSU, Japan—Toyoda Gosei is purchasing a majority stake in Hubei Rock Rubber and Seal Technology to strengthen its automotive parts business in China. $KIYOSU, Japan—Toyoda Gosei is purchasing a majority stake in Hubei Rock Rubber and Seal Technology to strengthen its automotive parts business in China.
Continental completes NVH footprint with Cooper Standard deal
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NOVI, Mich.—Certain opportunities are just too perfect to pass up. Continental A.G.'s Vibration Control business, which produces anti-vibration parts like engine mounts for the automotive...
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NOVI, Mich.—Continental's Vibration Controls business has agreed to acquire Cooper Standard's Anti-Vibration Systems business for $265.5 million, subject to closing conditions and antitrust approval in the relevant countries. NOVI, Mich.—Continental's Vibration Controls business has agreed to acquire Cooper Standard's Anti-Vibration Systems business for $265.5 million, subject to closing conditions and antitrust approval in the relevant countries. $NOVI, Mich.—Continental's Vibration Controls business has agreed to acquire Cooper Standard's Anti-Vibration Systems business for $265.5 million, subject to closing conditions and antitrust approval in the relevant countries.
DuPont to build $80 million plant in China
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ZHANGJIAGANG, China—DuPont Transportation & Advanced Polymers is investing more than $80 million to build a new manufacturing facility in Zhangjiagang that will produce "compounded high-...
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ZHANGJIAGANG, China—DuPont Transportation & Advanced Polymers is investing more than $80 million to build a new manufacturing facility in Zhangjiagang that will produce "compounded high-end engineering plastics and adhesives." ZHANGJIAGANG, China—DuPont Transportation & Advanced Polymers is investing more than $80 million to build a new manufacturing facility in Zhangjiagang that will produce "compounded high-end engineering plastics and adhesives." $ZHANGJIAGANG, China—DuPont Transportation & Advanced Polymers is investing more than $80 million to build a new manufacturing facility in Zhangjiagang that will produce "compounded high-end engineering plastics and adhesives."
Japan's auto makers wonder how to go more 'local' under USMCA
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TOKYO—North America's auto makers face a new reality of sourcing vehicle content under the free-trade deal agreed to by the U.S., Canada and Mexico. But for Japan's auto companies, the...
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TOKYO—North America's auto makers face a new reality of sourcing vehicle content under the free-trade deal agreed to by the U.S., Canada and Mexico. But for Japan's auto companies, the moment is particularly worrisome. TOKYO—North America's auto makers face a new reality of sourcing vehicle content under the free-trade deal agreed to by the U.S., Canada and Mexico. But for Japan's auto companies, the moment is particularly worrisome. $TOKYO—North America's auto makers face a new reality of sourcing vehicle content under the free-trade deal agreed to by the U.S., Canada and Mexico. But for Japan's auto companies, the moment is particularly worrisome.
BKT plans $100 million investment for U.S. tire plant
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MAHARASHTRA, India—Off-highway tire manufacturer Balkrishna Industries Ltd. (BKT) is budgeting $100 million for the plant it is planning to build in the U.S., the company disclosed in a Nov. ...
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MAHARASHTRA, India—Off-highway tire manufacturer Balkrishna Industries is budgeting $100 million for the plant it is planning to build in the U.S. MAHARASHTRA, India—Off-highway tire manufacturer Balkrishna Industries is budgeting $100 million for the plant it is planning to build in the U.S. $MAHARASHTRA, India—Off-highway tire manufacturer Balkrishna Industries is budgeting $100 million for the plant it is planning to build in the U.S.
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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