New DuPont modifier toughens PBTs, keeps them stiff
Hemel Hempstead, September 2005. 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, 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, heat deflection temperature values; demonstrate high
elongation and flow more easily during moulding than compounds prepared with
alternative tougheners, including conventional modifiers containing glycidyl methacrylate
“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 23ºC. In a 30 percent glass-reinforced resin with 10 percent modifier,
notched Izod is more than doubled at 23ºC and more than quadrupled at -20ºC. 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 201ºC (at 1.8 MPa
loading), just 2ºC lower than that of the unmodified resin.
Flow. In the injection moulding process, PBT modified with Elvaloy® PT862
exhibits better melt flow than PBT compounds prepared with conventional GMA-
containing modifier. In moulding 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
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. For more
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