Heat Deflection Temperature HDT

The greatest enhancement of HDT is seen with semi-crystalline thermoplastics such as PE, PP, polyamides and PET, with only minor enhancements achieved for filled amorphous 

---

Thermal Properties. Thermal properties include heat-deflection temperature (HDT), specific heat, continuous use temperature, thermal conductivity, coefficient of thermal expansion, and flammability ratings. Heat-deflection temperature is a measure of the minimum temperature that results in a specified deformation of a plastic beam under loads of 1.82 or 0.46 N/mm (264 or 67 psi, respectively). Eor an unreinforced plastic, this is typically ca 20°C below the glass-transition temperature, T, at which the molecular mobility is altered. Sometimes confused with HDT is the UL Thermal Index, which Underwriters Laboratories estabflshed as a safe continuous operation temperature for apparatus made of plastics (37). Typically, UL temperature indexes are significantly lower than HDTs. Specific heat and thermal conductivity relate to insulating properties. The coefficient of thermal expansion is an important component of mold shrinkage and must be considered when designing composite stmctures. 

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)... 

PCT forms the basis of a family of reinforced, crystalline plastics for injection molding. As mentioned above, the high melting point of the polymer is a key property, as this results in high heat deflection temperatures (HDTs) in glass-fiber-reinforced formulations. Good toughness, flow into the mold, and rapid crystallization are also important in these applications. 

Melting point (°C) Long-term resistance temperature in an unstressed state (°C) Heat deflection temperature, HDT 1.8 MPa (°C)... 

The practical goals of the fibre reinforcement are to increase the modulus and strength to improve the heat deflection temperature (HDT) to reduce the tendency to creep under continuous loading to save costs by decreasing the material cost used to obtain the same stiffening. 

Figure 7.8 shows the relationship between the heat deflection temperatures (HDT) and PVDF content of PVDF/PMMA blends. HDT is the starting temperature at which the polymer begins to deform under a certain stress. A minimum HDT is observed at a PVDF content of 50 wt %. The sharp increase in HDT is most likely due to the crystallization of PVDF in solid blends when the PVDF composition exceeds 50 wt %. The crystallites serve as temporary crosslinking sites to limit the mobility of polymer segments and thus to increase the heat resistance of PVDF/PMMA blends. When a blend has a PVDF content greater than 65 wt %, the material provides a heat resistance exceeding that of PMMA. 

From the practical point of view, the glass transition is a key property since it corresponds to the short-term ceiling temperature above which there is a catastrophic softening of the material. For amorphous polymers in general, and thus for thermosets, one can consider that the glass transition temperature, Tg, is related to the conventional heat deflection temperature (HDT) (usually, HDT is 10-15°C below Tg, depending on the applied stress and the criterion selected to define Tg). 

At elevated temperatures al polymers soften, dependent on their glass-rubber transition points, Tg, and/of their melting points, Tm. These temperatures limit the practical use of plastics. To characterize the softening behaviour, in practice various types of standard tests are being carried out, resulting in values for the softening temperature , defined in different ways. The values mostly used are the ISO Heat Deflection Temperature (HDT) and the Vicat Softening Temperature (VST or... 

Table 20.2 shows the effect on physical properties of a 2.5% letdown of a 70% Ti02 dispersion in liquid color. Tensile yield strength, Heat deflection temperature (HDT), and flexural strength and modulus are the only properties where there is some negative effect, essentially a plasticizing effect. Several properties in various resins are enhanced or unaffected. Consult this table before choosing a coloration system and decide what properties are important. 

Temperature has certainly an effect not only on the mechanical strength but also on the bond strength of the adhesive joints. Loss of strength occurs near the heat deflection temperature (HDT) (Lin and Deon, 1996). 

The lowest cost process for preparing all-arcmatic liquid crystalline polyesters involves the reaction of aromatic carboxylic acids with acetates of aromatic hydroxy ocnpounds a recent history (2) describes the development of these ICP s. Because aoetic acid is evolved in the process and reaction temperatures are above 300°C, expensive corrosion-resistant reactors must be installed for ccranercial production. In cur latest paper (2) of this ICP series, we described a number of aliphatic-aromatic ICP s which can be produced in conventional polyester reactors and injection molded to give plastics with very high mechanical properties, heat-deflection temperatures (HDT s), and solvent resistance. These ICP s (la) were prepared by the reaction of the dimethyl ester of... 

Because of low cost, high heat deflection temperature (HDT (104°C)), notched impact resistance, improved low temperature impact and flexibility, weather resistance, flame retardancy, and impact resistance, the PP/EPDM blend has got a widespread applications. These unique characteristics of this thermoplastic elastomer blend make it an attractive alternative to conventional elastomer in a variety of markets such as automobile industries, wire, cable insulator, automobile bumpers and fascia, hose, gaskets, seals, weather stripping, among others. 

Increased Heat-deflection temperature [HDT) Glass fibers Carbon fibers Fibrous minerals Ductility, cost Ductility, cost Ductility, cost Ductility, cost Ductility... 

P-FRs have both negative chemical and mechanical efferts in the resin, limiting their applications. For example, they are not usually used in thin applications, or in water-handling applications, because of their solubility and extraction tendencies. Moreover, as with mineral FRs, P-FRs tend to inaease modulus and heat-deflection temperature (HDT), while lowering impart strength and other mechanicals [1-1, 5-11, 5-13). 

Rein ncements Baron, carbon fibca-, glass fibca-, mineral fibta-, Kevlar Increases tensile strength, flexural modulus, and heat deflection temperature (HDT)... 

Figure 1.31 Heat deflection temperature (HDT) test apparatus.

Figure 3.116 Dissipation factor vs. frequency and temperature for Mitsubishi Engineering-Plastics lupiace AV 40—UL94 V-1 rated, heat deflection temperature (HDT) 100°C polypropylene ether, and PS blend resin.

AvaSpire AV-651—Better ductility and higher heat deflection temperature (HDT) than comparable PEEK, high melt flow for injection molding... 

---