Softness ranges

Polyvinyl Chloride (flexible) Softness range is that of rubber, extensibility proportionate to plasticizer used Bums with yellowish sooty flame, melts freely to form pearl like drops Flame turns green Sharp acrid fumes turn Congo paper blue Cyclohexane, tetrahydrofiiran and pyridine, solution turns red in presence of alcoholic potassium hydroxide solution... 

The use of thermoplastic olefins or TPOs is growing at a faster rate than the styrenic block copolymers (SBC) just discussed, or the thermoplastic vulcanizates (TPVs), which are discussed in the next section. The TPO growth rate is currently about 10% annually worldwide. Unlike the SBCs, certain TPOs can sometimes be used at higher service temperatures. Unlike the TPVs (which are derived through dynamic vulcanization), the TPOs are usually used uncured or are only very slightly vulcanized, if at all. This means that the TPOs are usually less costly than the TPVs. The TPOs have been very successful in the automotive industry in replacing the soft polyvinyl chloride compounds used in car interiors. TPOs are commonly available in softness ranges from 60 Shore A to 60 Shore D. A major use for TPOs is in the manufacture of automotive fascias, where appearance is very important. 

New ethylene ionomers have been developed over the last 35 years to offer expanded and improved performance capabilities. These developments include ionomers with different acid contents or counter-ions for improved resilience, with diverse rheological properties for various conversion processes, with improved adhesion to various substrates, with broader stiffness and softness ranges to facilitate rigid and flexible applications in a wider temperature range. 

Vaseline A trade name for soft paraffin. Yellow and white semi-solid, partly translucent mixtures of hydrocarbons of the paraffin series ranging from CijHji to C2oH42- Obtained from the high-boiling fractions of petroleum... 

It was found that that in the case of soft beta and X-ray radiation the IPs behave as an ideal gas counter with the 100% absorption efficiency if they are exposed in the middle of exposure range ( 10 to 10 photons/ pixel area) and that the relative uncertainty in measured intensity is determined primarily by the quantum fluctuations of the incident radiation (1). The thermal neutron absorption efficiency of the present available Gd doped IP-Neutron Detectors (IP-NDs) was found to be 53% and 69%, depending on the thicknes of the doped phosphor layer ( 85pm and 135 pm respectively). No substantial deviation in the IP response with the spatial variation over the surface of the IP was found, when irradiated by the homogeneous field of X-rays or neutrons and deviations were dominated by the incident radiation statistics (1). 

In the previous section, non-equilibrium behaviour was discussed, which is observed for particles with a deep minimum in the particle interactions at contact. In this final section, some examples of equilibrium phase behaviour in concentrated colloidal suspensions will be presented. Here we are concerned with purely repulsive particles (hard or soft spheres), or with particles with attractions of moderate strength and range (colloid-polymer and colloid-colloid mixtures). Although we shall focus mainly on equilibrium aspects, a few comments will be made about the associated kinetics as well [69, 70]. 

M. E. Tuckerman and B. J. Berne. Molecular dynamics in systems with multiple time scales Systems with stiff and soft degrees of freedom and with short and long range forces. J. Comp. Chem., 95 8362-8364, 1992. 

When freshly exposed to air, thallium exhibits a metallic luster, but soon develops a bluish-gray tinge, resembling lead in appearance. A heavy oxide builds up on thallium if left in air, and in the presence of water the hydride is formed. The metal is very soft and malleable. It can be cut with a knife. Twenty five isotopic forms of thallium, with atomic masses ranging from 184 to 210 are recognized. Natural thallium is a mixture of two isotopes. A mercury-thallium alloy, which forms a eutectic at 8.5% thallium, is reported to freeze at -60C, some 20 degrees below the freezing point of mercury. 

Terbium is reasonably stable in air. It is a silver-gray metal, and is malleable, ductile, and soft enough to be cut with a knife. Two crystal modifications exist, with a transformation temperature of 1289oC. Twenty one isotopes with atomic masses ranging from 145 to 165 are recognized. The oxide is a chocolate or dark maroon color. 

One reason for these difficulties is that metals have fairly soft bonding. This means that there is a nearly continuous range of values experimentally observed for any given metal-organic bond length. Likewise, inorganics more often exhibit distorted or fiuxional bond angles. There is also less vibrational data available to parameterize force constants. 

FI and FD are mild or soft methods of ionization that produce abundant molecular or quasi-molecular positive or negative ions from a very wide range of substances. In the FD mode, it is particularly useful for high-molecular-mass and/or thermally labile substances such as polymers, peptides, and carbohydrates. 

An abrasive is a substance used to abrade, smooth, or polish an object. If the object is soft, such as wood, then relatively soft abrasive materials may be used. Usually, however, abrasive coimotes very hard substances ranging from naturally occuring sands to the hardest material known, diamond. 

Much more information can be obtained by examining the mechanical properties of a viscoelastic material over an extensive temperature range. A convenient nondestmctive method is the measurement of torsional modulus. A number of instmments are available (13—18). More details on use and interpretation of these measurements may be found in references 8 and 19—25. An increase in modulus value means an increase in polymer hardness or stiffness. The various regions of elastic behavior are shown in Figure 1. Curve A of Figure 1 is that of a soft polymer, curve B of a hard polymer. To a close approximation both are transpositions of each other on the temperature scale. A copolymer curve would fall between those of the homopolymers, with the displacement depending on the amount of hard monomer in the copolymer (26—28). 

The combination of durability and clarity and the ability to tailor molecules relatively easily to specific applications have made acryflc esters prime candidates for numerous and diverse applications. At normal temperatures the polyacrylates are soft polymers and therefore tend to find use in applications that require flexibility or extensibility. However, the ease of copolymerizing the softer acrylates with the harder methacrylates, styrene, acrylonitrile, and vinyl acetate, allows the manufacture of products that range from soft mbbers to hard nonfilm-forming polymers. 

Spinel ferrites, isostmctural with the mineral spinel [1302-67-6] MgAl204, combine interesting soft magnetic properties with a relatively high electrical resistivity. The latter permits low eddy current losses in a-c appHcations, and based on this feature spinel ferrites have largely replaced the iron-based core materials in the r-f range. The main representatives are MnZn-ferrites (frequencies up to about 1 MH2) and NiZn-ferrites (frequencies 1 MHz). 

Typical textile fibers have linear densities in the range of 0.33—1.66 tex (3 to 15 den). Fibers in the 0.33—0.66 tex (3—6 den) range are generally used in nonwoven materials as well as in woven and knitted fabrics for use in apparel. Coarser fibers are generally used in carpets, upholstery, and certain industrial textiles. A recent development in fiber technology is the category of microfibers, with linear densities <0.11 tex (1 den) and as low as 0.01 tex. These fibers, when properly spun into yams and subsequendy woven into fabrics, can produce textile fabrics that have excellent drape and softness properties as well as improved color clarity (16). 

Ethylene vinyl acetate copolymer (EVA) forms a soft, tacky film with good water-vapor barrier but very poor gas-barrier properties. It is widely used as a low temperature initiation and broad-range, heat-sealing medium. The film also serves for lamination to other substrates for heat-sealing purposes. 

In the Rockwed test a spheroconical diamond (Brale) indenter or a hardened steel bad is used with various load ranges to achieve a series of scales identified by a suffix letter (Table 3). The suffix letter defines both load and indenter. The most popular scales used are "C" for hard materials and "B" for soft materials. A Rockwed hardness number is meaningless without the letter suffix, eg, HRC 54 or HRB 95. 

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