DURANEX® PBT, commonly known as polybutylene telephthalate (PBT), is a highly crystalline plastic. DURANEX is available in a wide variety of grades in four categories as shown below:
(1) Unreinforced grades and grades reinforced with glass fiber and/or other inorganic fillers.
(2) Slow burning and flame retardant grades.
Because the heat deflection temperatures of unreinforced grades are not sufficiently high for some industrial applications, most molded parts are made of reinforced grades; therefore, considerations to prevent deformation in molding are essential. Though such considerations include design of product shapes, mold design, and selection of grades, only the first two of these will be explained in this section.
DURANEX contains ester linkage in its polymer chain and care should be taken to avoid polymer degradation due to hydrolysis throughout the molding operation. Key points regarding this problem are how to control moisture level of the pellets, resin temperature and the residence time in the cylinder.
Some aspects of general mold design for DURANEX are common to those for DURACON® POM, so we recommend that you also refer to "Molding Technology for DURACON® POM".