Heat Distortion Temperature HDT

Polymers with differing morphologies respond differentiy to fillers (qv) and reinforcements. In crystalline resins, heat distortion temperature (HDT) increases as the aspect ratio and amount of filler and reinforcement are increased. In fact, glass reinforcement can result in the HDT approaching the melting point. Amorphous polymers are much less affected. Addition of fillers, however, intermpts amorphous polymer molecules physical interactions, and certain properties, such as impact strength, are reduced. 

The DTUL, also called the heat distortion temperature (HDT) of a plastic is a method to guide or assess its load-bearing capacity at an elevated temperature. Details on the method of testing are given in ASTM D648. Basically a 1.27 cm (V2 in.) deep plastic test bar is mounted on supports 10.16 cm (4 in.) apart and loaded as a beam. A bending stress of either 66 psi or 264 psi (455 gPa or 1,820 gPa) is applied at the center of the span. 

Heat deflection temperature (HDT), 45 Heat distortion temperature (HDT), 242 Heck coupling, 489... 

TDI isomers, 210 Tear strength tests, 242-243 TEDA. See Triethylene diamine (TEDA) Telechelic oligomers, 456, 457 copolymerization of, 453-454 Telechelics, from polybutadiene, 456-459 TEM technique, 163-164 Temperature, polyamide shear modulus and, 138. See also /3-transition temperature (7)>) Brill temperature Deblocking temperatures //-transition temperature (Ty) Glass transition temperature (7) ) Heat deflection temperature (HDT) Heat distortion temperature (HDT) High-temperature entries Low-temperature entries Melting temperature (Fm) Modulu s - temperature relationship Thermal entries Tensile strength, 3, 242 TEOS. See Tetraethoxysilane (TEOS)... 

Proper selection of plastic matrix fire retardants and property enhancers offers acceptable combinations of impact properties and heat-distortion temperature (HDT) values for fire retardant plastics. This can be demonstrated by fire retardant styrenics. Fire retardant enhancers have special interest as property enhancers for example the addition of a highly flammable material such as ethylene propylene diene terpolyer (EPDM), dramatically improves the bromine efficiency of octabromodiphenyl oxide in ABS by increasing char-forming without changing the Sb-Br reaction. 

The heat distortion temperature (HDT) is greatly improved by the glass from 59 to 216 °C, while the notched Izod impact is similar to PET and slightly better than PBT. 

The heat distortion temperatures (HDTs) of the injection molded specimens were determined under a load of 1.82 MPa according to ASTM D-648. 

Figure 19.12 Relationship between the heat distortion temperature (HDT) (at 1.82 MPa) and Tg for the amorphous polyarylates of HBA/Ph-HQ or fBu-HQ/HQ/ BB and the crystalline polyarylate of Ph-HQ/BB [33]...

Finally, in the English-speaking countries, there is another extensively used method in which a rod is supported at its two ends and a load is placed on the center this is slowly heated in a liquid bath until a certain distortion is attained the temperature at which this occurs is called the heat distortion temperature (HDT). These methods are applicable both to thermoplastics and to crosslinked polymers. Interconversion of the softening temperatures determined by the different techniques is not possible. 

Heat distortion temperatures (HDTs) are widely used as design criteria for polymeric articles. These are temperatures at which specimens with particular dimensions distort a given amount under specified loads loads and deformations. Various test methods, such as ASTM D648, are described in standards compilations. Because of the stress applied during the test, the HDT of a polymer is invariably higher than its Tg. 

The heat distortion temperature (HDT) is a function of the cross-link density and depends upon the type of glycol. In the case of propylene and diethylene glycol, the HDT becomes smaller at higher levels of unsaturation. 

Heat distortion temperature (HDT) The temperature at which the properties of a polymeric material are distorted. 

The Figure 2-7 TMA plots indicate that the dimensional changes of the XYDAR molded parts are fairly linear over a wide temperature range. The applicable range for TMA measurements on these materials appears to be up to their heat distortion temperature (HDT). For the 300 series formulations shown in Figures 2-7 the HDT is in the 200-250 C range. 

In practice, the "heat distortion temperature" (HDT) is used more often than Tg in product literature for commercial polymers as an indicator of the mechanical softening temperature. It is closely related to (usually slightly lower than) Tg for amorphous polymers. It has been shown [2] to correspond roughly to the temperature at which the shear modulus falls to 280 MPa. See Section 20.B.1 for further discussion of the HDT. 

PPO resins with very high heat distortion temperatures (HDTs) can readily raise the HDT of styrenics to over 100 °C, which is a significant temperature because this qualifies the product for all boiling water applications. 

Heat Deflection Temperature - The temperature at which a material specimen (standard bar) is deflected by a certain degree under specified load. Also called rensi/e heat distortion temperature, heat distortion temperature, HDT, deflection temperature under load. 

Heat Distortion Temperature (HDT) - See Heat Deflection Temperature. 

Quite generally, the goal in any blending of polymers is to obtain one or all of the following benefits higher heat distortion temperature (HDT), improved variable temperature impact resistance, solvent resistance, dimensional tolerance, higher flow, utilization of recycle/regrind, and lower cost. 

The heat distortion temperature (HDT), the deflection temperature under load (DTUL), or the softening temperature are practical and important parameters of a polymeric material. They denote... 

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