Plastic softening range

Plasticizers soften the film and increase the adhesion and the setting speed. The most common are phthalates, adipates and benzoates. The amount added can be in a broad range of 10-50%. They affect the swelling and softening of the PVAc emulsion particles, ensure film formation at room temperature, and the tack of the still wet adhesive. They also provide improved moisture resistance of the bond. Disadvantages are the lower resistance of the bond line against heat, possible migration of the plasticizers and enhanced cold flow. 

Softening range Temperature range in which a plastic transforms from a rigid solid to a soft state. 

With crystalline types [not amorphous (Chapter 1)], melt leaving the die (and moving to a ring-shaped zone where the film approaches its diameter) changes from a hazy to a transparent (amorphous) condition. The level at which this transition occurs is the frost line. This zone is characterized by a frosty appearance to the film caused by the film temperature falling below the softening range of the plastic. 

The final action required is reheating the molded part at which time the plastic softens and the gas expands to form a closed-cell foam. With this technique it is possible to produce foams with densities as low as 2 lb/ft3, although the usual range is 10 to 50 lb/ft3. Because of this two-step procedure the process is much slower than the foaming procedure for open-cell foams. Close cell use includes athletic mats and marine flotation products. 

Fig. 2 Temperature-dependence of the modulus of elasticity (Young s modulus) of plastics (diagram). As an alternative to this modulus, tension a can also be plotted against constant elongation e or viscosity i), or other properties [2]. MSRe x,d- main softening range of elastomers, thermoplastics, duroplastics, Tgt associated glass transition temperature, Tfi flow point of the amorphous thermoplastic, //////// application range, application range...

In eqs. (8.42) we recall that the dilatancy factor depends on f, the liquid-like-material fraction, which increases with increasing plastic strain -f (or e ) from a low value cp- of around 0.05 at -f= 0 in the annealed structure to = 0.5 in the flow state through the strain-softening range and remains stationary after that. In the stress-strain relationship all plastic strains are represented as the true equivalent plastic strain sP, where we recall that... 

The thermal decomposition of coal is a complex sequence of events (Stein, 1981 Solomon et al., 1992) (Chapters 13 and 16) that can be described in terms of several important physicochanical changes, such as the tendency of the coal to soften and flow when heated (Chapters 8 and 9) or the relationship to carbon type in the coal (Solomon, 1981). In fact, some coals become quite fluid at temperatures of the order of 400°C-500°C (750°F-930°F) and there is a considerable variation in the degree of maximum plasticity, the temperature of maximum plasticity, as well as the plasticity temperature range for various coals (Kirov and Stephens, 1967 Mochida et al., 1982 Royce et al., 1991). Indeed, significant changes also occur in the structure of the char during the various stages of devolatilization (Fletcher et al., 1992). 

Softening range n. A temperature interval over which a plastic changes from a rigid to a soft state or undergoes a rather sudden... 

Polyamides designed for bonding plastics are functioning to make heat-shrinkable sleeves in electrical applications and for sealing electrical connectors. Polyamides containing a secondary diamine, with a wide softening range, are chosen because of their better adhesion properties and easy activation. 

The solid resins are clear, colorless, odorless, and tasteless, with a wide molecular weight distribution and a broad softening range. They are soluble in ketone and ester solvents and are readily plasticized. PVA is used in coatings and adhesives, as a chewing gum base, and as an intermediate in the production of poly(vinyl alcohol), PVOH. 

Plasticizers are substances of low or negligible volatility that lower the softening range and increase workability, flexibility, or extensibility of a polymer (ASTM D907-08b 2008). 

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