Initial softening temperature

The synthesis of phenylene R type systems via the proposed route afforded two materials which had both final Tg s above the 350°F limit and initial Tg s which were at or below room temperature. The two systems which offered the most desirable properties were those based on resorcinolAg-dibromobenzene and hydroquinone/m-dibromobenzene. Of the two, the hydroquinone system offered a lower initial softening temperature while also providing a cured Tg above 200°C. For this reason the product from hydroquinone and m-dibromobenzene was chosen as the candidate system for future work. 

Initial softening temperature temperature at which the dial movement reaches 1.0 dial division per minute (100 dial divisions = one complete revolution of the stirrer) may be characterized by other rates, but if so, the rate must be reported. 

A comparison between the IGC results for Upper Freeport coal with results obtained via Giesler plastometry is presented in Figure 8. The marked increase in retention volume that indicates the start of the third region correlates well with the initial softening temperature. For the coals investigated thus far, the transition is observed in the IGC 10 to 15 0 before the initial softening temperature. 

Figure 2.26. A typical fluidity curve. 7, initial softening temperature and T solidification temperature (Marsh etai, 1997).

Ash Fusibility. A molded cone of ash is heated in a mildly reducing atmosphere and observed using an optical pyrometer during heating. The initial deformation temperature is reached when the cone tip becomes rounded the softening temperature is evidenced when the height of the cone is equal to twice its width the hemispherical temperature occurs when the cone becomes a hemispherical lump and the fluid temperature is reached when no lump remains (D1857) (18). 

The variation in the initial Tg s show the effect on processability of the structures of the diol and the dibromobenzene. Two of the systems, those based on thiodiphenol and dihydroxybiphenyl, gave crystalline products which could not be made amorphous upon heat treatment. The effect on chain flexibility of dibromobenzene structure could be seen with the two hydroquinone systems. In this case, the meta isomer gave an initial Tg of 12°C while the more rigid para system had a Tg of 59°C. Variation of diol structure shows a parallel effect as shown with the resorcinol/j>-dibromobenzene system. This material has a softening temperature of 20°C. 

Both unplasticised and plasticised PVC shrink films are available. Plasticised material feels softer to touch, is less brittle, has a lower softening point and shrinkage. Unplasticised PVC has good surface gloss and clarity, but tends to be brittle, of poor impact strength and rather easy to tear once initiated. Shrink temperature is around 90-100°C. 

Friction stir welding has been applied to metals with moderate melting points. Initially, FSW was applied primarily to aluminum alloys, which could be easily welded due to the relatively low softening temperatures of these alloys. Other relatively soft metals, such as copper, lead, zinc, and magnesium, have also been welded. In contrast, for a number of years it was difficult to weld ferrous alloys and other high-softening-temperature metals due to the lack of suitable tool materials. 

Commercial lithium aluminosilicate glass-ceramics provide excellent examples of such behavior. The initial glass used for production of transparent cookware, for example, has a thermal expansion coefficient of 4 ppm K , Tg 730 °C, and T = 760 °C. After processing, the thermal expansion coefficient is == 0.5 ppm K and Tg and T can no longer be detected on an expansion curve below 1000 °C. Heat treatment results in the formation of a lithium aluminosilicate crystal which has a very low thermal expansion coefficient. Removal of lithium from the residual glassy phase also decreases the thermal expansion coefficient of that phase, while simultaneously increasing the transformation and softening temperatures. 

The quinoxalline pol5mers, possessing higher glassing and softening temperatures and better mechanical properties compared to initial polymers, have been produced by means of interaction of polyester-a-diketones with a-phenylenediamine at 23 °C in m-cresol. Polyquinoxa-lines are amorphous pol5mers, soluble in chlorinated, amide and phenol dissolvents with = 0.4-0.6 dL/g (25 °C, in N-methylpirrolydone of 0.5 gram/deciliter). 

PE can be prepared for carbonization by treating with chlorosulfonic acid at 60 90°C, or 98% H2SO4, at 100-180°C. Initially, the temperature should be maintained below the softening point of PE and gradually increased as the temperature resistance of the fiber increases [308]. The... 

Compression molding—the laminate is heated beyond its softening temperature using hot air or infrared and pressed into the required shape. A heated platen press can be used to initially heat the laminate. 

Adhesive joints may be subjected to a variety of adverse service conditions, including elevated temperature, organic solvents, water and stress (see Durability fundamentals. Durability creep rupture). Solvent-based, emulsion and melt adhesives are normally based on thermoplastics with fairly low softening temperatures. If a loaded joint is subjected to elevated temperature, failure may occur because of Creep unless the adhesive is cross-linked. Likewise, attack by organic solvents can be minimized by cross-linking. Solvent-based, emulsion and hot melt systems are available that cross-Unk after the initial bonding has been carried out. These systems provide improved in-service performance. 

Thermal Mechanical Analysis (TMA). TMA thermograms were obtained using a Perkin Elmer TMS-1 in the penetration mode on samples of cast resin film. The reported glass transition temperatures were identified as temperature of initial softening of the resin when heated at 10 C min under a load of... 

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