Waxes microcrystalline

Microcrystalline waxes, produced from heavy lubricating oil residues, have a micro-crystalline structure and consist largely of iso-and cycloalkanes with some aromatics. 

The exact formulations for inlay casting waxes are considered trade secrets, and Htfle has been pubUshed on the subject. A binary mixture of 65—75 wt % paraffin wax (60—63°C) and a microcrystalline wax having a melting point >60° C has been suggested (127). This produces a mixture having a sohd—sohd transition point at about 37°C with htfle plastic deformation (1—3%) at 37°C and a desirable plasticity at 45°C (73—77%) (128). 

Base-plate wax compositions are generally regarded as trade secrets. A substantial percentage of paraffin is usually present, probably 50—80 wt %. Beeswax [8012-89-3] camauba wax [8015-86-9] ceresin, microcrystalline waxes, Acrawax C (Glyco Products Co. Inc.), mastic gum, rosin [8050-09-7] and synthetic resins may make up the balance of the formulation. Base-plate waxes are generally sold in sheet form about 1.3 mm thick, 75 mm wide, and 140 mm long. 

The compositions of sheet and shape waxes are also trade secrets. However, they are blends of various proportions of paraffin, microcrystalline waxes, camauba wax, ceresin, beeswax, gum dammar, mastic gum, and possibly other resins. Sheet waxes are marketed in square sheets approximately 80 by 90 mm. Various thicknesses are available from 32 gauge (0.5 mm) to 14 gauge (1.63 mm). 

Bite-Registration Waxes are used to estabhsh the occlusion or horizontal relationship of the lower jaw to the upper jaw when there are opposing teeth present. Bite waxes may have a flow of 84% at 30°C. They are generally compounded from high-flow, low-melting paraffins, microcrystalline waxes, and resins. 

Rather, microcrystalline waxes are used to provide adhesives with longer open times and better low temperature adhesion, due to better wet out, and toughness. 

Microcrystalline waxes can also act as an antiblock and can provide some processing benefits. Polymeric antiblocks based on organic particles have also recently been introduced. 

Microcrystalline wax is found worldwide as a constituent of crude oil. It is removed by solvent extraction and distillation. The colour varies, depending on grade, from white to brown black. It has many uses, including waterproofing paper and textiles, and as a sealant. This wax consists of a mixture of long chain (C41 C57) unsaturated hydrocarbons with an average molecular weight of 500 800. 

These waxes have branched structures of higher molecular weight (40-70 carbon atoms) than paraffin waxes and form a quite different crystalline structure on the surface of the rubber when emerging from solution from within the vulcanised rubber. Microcrystalline waxes form smaller crystals, which pack tighter together to form a more coherent, much more flexible film on the rubber surface which is more resistant to ozone penetration. 

Wax is of two general types (1) paraffin wax in petroleum distillates, and (2) microcrystalline wax in petroleum residua. 

Microcrystalline wax wax extracted from certain petroleum residua and having a finer and less apparent crystalline structure than paraffin wax. 

Saturated Paraffin waxes, microcrystalline wax, earth wax, polyethylene waxes. 

Sample thickness and sample uniformity present serious problems. The ideal sample is a uniform foil or a homogeneous solution. For metals the optimum thickness is in the micron range. Most of the samples studied here were powders, ground to pass 300 mesh, dispersed in a ductile microcrystalline wax. This wax dispersion is then spread to a uniform film across a sample holder window. The window has dimensions 3 X 17 mm. Adhesive cellophane tape is frequently spread over the window to assist in the mounting and supporting of the sample. 

The term microcrystalline wax is commonly used to describe wax which is either mal-shaped or needlelike. This wax typically contains molecules >30 carbons in length. This wax can be present in various high-boiling-point fractions such as residual fuel oil and lubricant fractions. 

Because the forces of attraction prevail when molecules are brought into sufficiently dose proximity under normal conditions, release is best effected if both the strength of the interaction and the degree of contact are minimized. Aliphatic hydrocarbons and fluorocarbons achieve the former effect, finely divided solids the latter. Materials such as microcrystalline wax [64742 42-3] and hydrophobic silica [7631-86-9] combine both effects. Some authors refer to this combined effect as the ball bearing mechanism. A perfluoroalkylated fullerene nanosphere would perhaps be the ultimate example of this combined effect (17). These very general mechanistic remarks can be supplemented by publications on the mechanism of specific classes of release agents such as metallic stearates (18), fatty acids and fluorinated compounds (19), and silicone-coated rdease papers (20,21). The mechanism of release of certain problem adherents, eg, polyurethanes, has also been addressed (22,23). 

Formulation Silicon Polypropylene (major binder) Microcrystalline wax (minor binder) Stearic acid... 

Using silicon nitride powder in a polypropylene/microcrystalline wax/stearic acid binder formulation, the effect of filler volume fraction (V) (over the range 50 to 70%) on relative viscosity (rjj.) was predicted from Eq. 5 ... 

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