Distortion temperature under load

TetrabromobisphenoIA. Tetrabromobisphenol A [79-94-7] (TBBPA) is the largest volume bromiaated flame retardant. TBBPA is prepared by bromination of bisphenol A under a variety of conditions. When the bromination is carried out ia methanol, methyl bromide [74-80-9] is produced as a coproduct (37). If hydrogen peroxide is used to oxidize the hydrogen bromide [10035-10-6] HBr, produced back to bromine, methyl bromide is not coproduced (38). TBBPA is used both as an additive and as a reactive flame retardant. It is used as an additive primarily ia ABS systems, la ABS, TBBPA is probably the largest volume flame retardant used, and because of its relatively low cost is the most cost-effective flame retardant. In ABS it provides high flow and good impact properties. These benefits come at the expense of distortion temperature under load (DTUL) (39). DTUL is a measure of the use temperature of a polymer. TBBPA is more uv stable than decabrom and uv stable ABS resias based oa TBBPA are produced commercially. 

S/MA/MM). Miscibility behavior of typical matrix pairs is discussed as a function of composition, and discussion of material behavior in this work emphasizes response to elevated temperatures and to stress at temperature extremes. Thus, glass transition temperature (Tg), distortion temperature under load (DTUL), and tensile deformation properties as a function of temperature are reported for various typical blend combinations. Also discussed are the results of elevated temperature air aging studies on a typical blend compared to ABS. 

Figure I. Effect of maleic anhydride content on distortion temperature under load (DTUL) and on glass transition temperature (Tg). Key o, Si MA copolymer and a. Si MAI MM terpolymer (ca. 6% MM).

Nylon-SAN, which has a high impact strength of 16 ft.-lb/in. of notch (854 J/m), has received a UL (Underwriters Laboratory) rating of 104°C. The nylon-arylate blend is transparent and has a heat-distortion temperature under load (264 Ibf/in. ) value of 154°C. 

Serlzawa et al. reported high-performance biomass-based plastics that consist of PLA and kenaf fiber. Adding kenaf fiber to PLA greatly Increased its heat resistance (distortion temperature under load) and modulus and also enhanced its crystallization [48]. 

Material SG Tensile Strength psi Flexural Modulus psi Izod Impact Strength ft Ib/in Distortion Temperature Under Load G 264 psi Co-efficient of Linear Thermal Expansion... 

For a given notched-lzod value, a higher melt flow can be obtained via use of a copolymer than with the corresponding BPA homopolymer (e.g., Lexan resins). For example, Lexan SP grades possess almost twice the melt flow index (MFI) of the BPA homopolymer resins at a 640 J/m (12 ft Ib/in) notched Izod. The tradeoff for the increased flow is a corresponding decrease in the distortion temperature under load (DTUL) of 20°C, as shown in Fig. 14.7. These resins are being supplanted by the siloxane-BPA polycarbonate (see the section PC Siloxane Block Copolymers ), which provide an even better balance of melt flow and ductility without a significant loss in heat performance. 

CLTE (MD), coefficient of linear thermal expansion DTUL, distortion temperature under load. 

Regardless of the quantity and ready availability of this information, how can published Izod impact behavior be successfully used to make a better, more durable product How can the Distortion Temperature Under Load (DTUL) of a material translate into practical continuous use temperature What publi ed data are really useful And what are meaningless ... 

Two particular test methods have become very widely used. They are the Vicat softening point test (VSP test) and the heat deflection temperature under load test (HDT test) (which is also widely known by the earlier name of heat distortion temperature test). In the Vicat test a sample of the plastics material is heated at a specified rate of temperature increase and the temperature is noted at which a needle of specified dimensions indents into the material a specified distance under a specified load. In the most common method (method A) a load of ION is used, the needle indentor has a cross-sectional area of 1 mm, the specified penetration distance is 1 mm and the rate of temperature rise is 50°C per hour. For details see the relevant standards (ISO 306 BS 2782 method 120 ASTM D1525 and DIN 53460). (ISO 306 describes two methods, method A with a load of ION and method B with a load of SON, each with two possible rates of temperature rise, 50°C/h and 120°C/h. This results in ISO values quoted as A50, A120, B50 or B120. Many of the results quoted in this book predate the ISO standard and unless otherwise stated may be assumed to correspond to A50.)... 

In the deflection temperature under load test (heat distortion temperature test) the temperature is noted at which a bar of material subjected to a three-point bending stress is deformed a specified amount. The load (F) applied to the sample will vary with the thickness (t) and width (tv) of the samples and is determined by the maximum stress specified at the mid-point of the beam (P) which may be either 0.45 MPa (661bf/in ) or 1.82 MPa (264Ibf/in ). 

To enhance the resistance to heat softening his-phenol A is substituted by a stiffer molecule. Conventional bis-phenol A polycarbonates have lower heat distortion temperatures (deflection temperatures under load) than some of the somewhat newer aromatic thermoplastics described in the next chapter, such as the polysulphones. In 1979 a polycarbonate in which the bis-phenol A was replaced by tetramethylbis-phenol A was test marketed. This material had a Vicat softening point of 196 C, excellent resistance to hydrolysis, excellent resistance to tracking and a low density of about l.lg/cm-. Such improvements were obtained at the expense of impact strength and resistance to stress cracking. 

Heat distortion temperature (deflection temperature under load) of cured... 

The ASTM heat distortion temperature (deflection temperature under load) test may be used to characterise a resin. Resins must, however, be compared using identical hardeners and curing conditions. 

Heat-Distortion Temperature (see also Deflection Temperature Under Load)... 

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. 

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... 

Two particular test methods have become very widely used. These are the Vicat softening point test and the test widely known as the heat distortion temperature test (also called the deflection temperature under load test). In the Vicat softening point test a sample of polymer is heated at a specified rate temperature increase and the temperature is noted at which a needle of specified dimensions indents into the polymer a specified distance under a specified load. 

The structures and glass transition temperatures of several commercial polysulfones are listed in Table 4.30. The polymers have different degrees of spacing between the p-phenylene groups and thus have a spectrum of glass transition temperatures which determine the heat-distortion temperature (or deflection temperature under load), since the materials are all amorphous. 

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