Focus
on Research
Penn State Intercom......November
15, 2001
Addition of clays make
better, cleaner plastics
By A'ndrea Messer
Public Information
Small amounts of well-dispersed natural clay can lead to environmentally friendly and inexpensive plastic composites with improved specialized properties, according to a University researcher.
"Adding very small amounts of natural clays to plastics changes some of their physical properties," said Evangelos Manias, assistant professor of materials science and engineering. "While we can tune the chemical interactions between the clays and some polymers, it is the general changes due to the nanometer fillers in all plastics that may be the most interesting."
Addition of clay can make plastics less permeable to liquids and gases, more flame retardant and tougher. Lower permeability can make plastics like PET, the standard plastic used in soft drink bottling, suitable for bottling beer or wine. The clay-enhanced product would protect the beverages from the effects of oxygen. At the same time, the addition of small amounts of clay does not affect the transparency of plastics.
Adding clay to polymer blends is not a simple process as polymers and clays mix about as well as oil and water. However, if the clay is treated with an organic surfactant, a compound that allows the inert clay to mix with the polymers, much as soap allows oil and water to mix, the clays can be incorporated into the final product.
An inexpensive, more environmentally clean method of producing flame retardant plastics could eventually save lives. Because the addition of clay into plastics reduces flammability in a wide range of plastics, it may have universal application as a general flame retardant additive.
"Currently, chemicals used to make plastics flame retardant contain bromine, which produces poisonous combustion gases when burned," Manias said. "Using clay is a green alternative to current practices and reduces flammability in a wide range of plastics."
The polymer clay blends, while containing only 1 percent to
5 percent clay, are actually nanocomposites. The addition of clay into the polymer blend does not alter the normal production and processing of the clayless polymer.
"The clay can be added at the final stages of polymer processing without any change in the current industrial practices," Manias said. "The thermodynamics drive the nanometer dispe rsion of the clay through the polymer and the small amounts of clay do not cause any wear in the equipment. Manufacturers can use the same equipment, timing and settings as in their normal process."
A'ndrea Messer can be reached at aem1@psu.edu.
Cocoa, dark chocolate have
positive effect on 'bad' cholesterol,
according to preliminary study
By Barbara Hale
Public Information
A University-led study has found that a diet high in flavonoid-rich cocoa powder and dark chocolate had favorable effects on LDL ("bad" cholesterol) when compared with a diet that limited or excluded other flavonoid sources such as tea, coffee, wine, onions, apples, beans, soybeans and orange and grape juices.
Penny Kris-Etherton, distinguished professor of nutrition and leader of the study, said, "Cocoa and chocolate are 'fun foods' and I think these results show that they can contribute to a healthy diet -- especially if they are used in forms that don't include large amounts of fat and sugar. However, cocoa and chocolate shouldn't be considered significant sources of flavonoids in the same category with fruits and vegetables which also have fiber, vitamins and minerals."
The current study was the first to evaluate and compare LDL (low density lipoprotein) susceptibility to oxidation when the test subjects, 23 men and women, ate an average American diet purposely made low in flavonoids and a diet that contained about one and a quarter ounces (38 grams) of cocoa powder and dark chocolate which are rich flavonoid sources. Oxidation of LDLs is thought to play an important role in the development of atherosclerosis or hardening of the arteries. Increasing LDL's resistance to oxidation is thought to possibly delay the progression of the disease. Flavonoids, which are present in a wide variety of plants, have long been known to inhibit LDL oxidation.
Kris-Etherton's co-researchers are Ying Wan, who earned her master of science in nutrition at Penn State; Joe Vinson, a faculty member at the University of Scranton; Terry D. Etherton, distinguished professor and head of the dairy and animal science department; John Proch, a technician at the University of Scranton; and Sheryl A. Lazarus, scientist in the Analytical and Applied Science Group, Mars Inc. The study was supported by the American Cocoa Research Institute.
The subjects had blood drawn at the end of each diet period. The LDL was extracted from each blood sample and then subjected to oxidation in the laboratory. The researchers noted the amount of time it took for oxidation to begin, the rate at which oxidation proceeded and the amount of oxidized fatty acid produced.
When the subjects ate the cocoa and chocolate-containing diet, oxidation occurred about 8 percent slower compared to when they ate the experimental average American diet. Analysis of their blood plasma also showed that total antioxidant capacity was 4 percent greater after the cocoa and chocolate containing diet. HDL cholesterol (the "good" cholesterol) was 4 percent higher after the chocolate diet than after the average American diet.
Barbara Hale can be reached at bah@psu.edu.
Flexibility helps build
competitive advantage
By Steven M. Infanti
Smeal
College of Business Administration
Two University professors have developed a new method that will allow firms to more accurately estimate the additional cash flow a capital purchase can generate.
In recent years many firms have found it increasingly important to invest substantially in technology to maintain a competitive edge. Firms, however, often overlook the value of manufacturing flexibility when considering capital purchases and that can cost them millions.
"If a firm is analyzing the purchase of a new machine, it is easy to determine the value of added capacity or increased production efficiency, but most firms overlook the value of increased manufacturing flexibility," noted Elena Katok, assistant professor of management information systems in the Smeal College of Business Administration.
She recently co-developed a practical method for research planning under uncertainty. William Tarantino of the Center for Army Analysis at Fort Belvoir, Va., and Terry P. Harrison, professor of management science, worked with her.
The researchers were able to show the approach they developed is more accurate than several commonly used methods and successfully applied the approach to an investment problem faced by a major aviation industry firm. Their recommendations resulted in an estimated annual savings in excess of $1 million.
Technological improvements often require superior production methods, and some firms find themselves constantly evaluating opportunities for investments in new production resources. Production investment decisions are extremely difficult because they involve planning under uncertainty. Decision flexibility, Harrison noted, is the ability to postpone decisions until more information is obtained. When a new production resource is added to the current system, it can increase decision flexibility by either providing additional capacity where it is needed, or by providing an additional routing for a part.
Steven Infanti can be reached at smi3@psu.edu,