New DuPont Modifier Toughens PBTs, Keeps Them Stiff and Strong, Too
September 27, 2005
WILMINGTON, Del. -- PBT (polybutylene terephthalate) resins modified with a new DuPont toughening agent deliver sharp increases in impact resistance while key engineering and processing properties remain largely intact. The new toughener, DuPont?Elvaloy?PT862 polymer modifier from DuPont Packaging & Industrial Polymers, is part of a broad range of property-enhancing additives supplied under the DuPont?Elvaloy?and Fusabond?brands.
Test data show that PBT compounds containing Elvaloy?PT862 retain more of their original stiffness, strength and heat deflection temperature values; demonstrate high elongation and flow more easily during molding than compounds prepared with alternative toughners, including conventional modifiers containing glycidyl methacrylate (GMA) terpolymer.
"Elvaloy?PT862 gives compounders a valuable new tool for tailoring the properties of PBT resins to application requirements," said Penny L Perry, Ph.D., director, DuPont Industrial Polymers. Typical applications for toughened PBT include electrical and electronic components such as connectors as well as components for various other industrial and consumer products.
Impact improvement at ambient and low temperatures.
When a typical unreinforced PBT is compounded with 15 percent of the new toughener, its notched Izod impact strength rises to 10 to 12 times that of the unmodified polymer at temperatures between 0 and 23?C. In a 30 percent glass-reinforced resin with 10 percent modifier, notched Izod is more than doubled at 23?C and more than quadrupled at -20?C. Significant impact improvement is also achieved at 5 to 10 percent use levels.
Strength and stiffness retention.
A typical unreinforced PBT with 15 percent of Elvaloy?PT862 retains more than 80 percent of its original tensile strength and flexural modulus (stiffness). A 30 percent glass-reinforced resin with 10 percent of the toughener retains nearly 90 percent of its tensile strength and over 75 percent of its original flexural modulus values. These properties are superior to those of PBT formulated with conventional GMA-containing modifiers.
High temperature capability.
The heat deflection temperature (HDT) of the 30 percent glass-reinforced PBT resin with 10 percent Elvaloy?PT862 is 201?C (at 1.8 MPa loading), just 2 degrees lower than that of the unmodified resin.
Flow.
In the injection molding process, PBT modified with Elvaloy?PT862 exhibits better melt flow than PBT compounds prepared with conventional GMA-containing modifier. In molding parts such as connectors with thin wall sections and/or long flow paths, the excellent flow of PBT toughened with the new modifier improves productivity by widening the process window and reducing clamping pressure requirements
Other PBT-compatible grades of Elvaloy?allow compounders to achieve property combinations different from those achieved with the new Elvaloy?PT862. Super-tough PBT grades, for example, can be produced with Elvaloy?PTW.
A wide range of DuPont polymer modifiers is available to enhance the properties and processing of many engineering plastics and other thermoplastic resins.
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