Lubricant external

Extensional viscosity Extension cord External lubricant External plasticizers Exterol Exter press Exton... 

A-C 7 A-C 7A A-C 8 A-C 8A A-C 9 A-C 9A A-C 9F lubricant, externai enxiisions Cardis 314 Cardis 320 lubricant, external PE Hydrobrite 1000PO lubricant, external polymers Hydrobrite 1000PO Zonyi FS-300 Zonyi FSO... 

Cardis 314 Cardis 320 lubricant, external PP Hydrobrite 1000PO lubricant, external PVC... 

Guar (Cyanopsis tetragonoloba) gum Sorbitan sesquioleate Synthetic wax lubricant, external auto polishes Microcrystalline wax, oxidized... 

Lubricants are used with polymers for two main needs external lubrication and internal lubrication. External lubrication reduces friction between the polymer and the extrusion hardware, such as on the internal flow surfaces of the die. For example, lubricants can help eliminate melt fracture of blown film by reducing stress on the polymer as it passes through the die. Additionally, die drool (or die lip buildup) has been reduced by the use of lubricants. Internal lubrication reduces the friction between flowing polymer molecules, effectively reducing melt viscosity. Use of internal lubricants can reduce the power consumption required for polymers that are difficult to process. Some common lubricants are metal stearates and paraffin waxes. 

The pressure drop in the feedblock is important because the balance between the fluxes for the three layers is achieved by a strong annular restriction in the flow channel. This restriction is similar to a chocker bar on a flat die. Lubrication (external and internal) is used to reduce the pressure drop in the feedblock-die assembly and hence, to reduce the outlet pressure at the extruder. 

External Lubricants. External lubricants are substances with very low solubility in the polymer they exude partially from the bulk, creating a separating layer between the polymer and the metal surface of the processing machine. It is believed that the polar end of the lubricant molecules is strongly adsorbed to the metal surface so as to form a stationary layer of lubricant molecules that then initiates the formation of a multimolecular layer as shown in Fig. 2.6 [19]. The strength of the bond between a lubricant molecule and the metal surface depends on the nature of the metal surface it determines whether the adsorp-... 

Elastomers Adhesives Sonar domes Hoses (water and fuel) Sealants (fuel and water tanks) Conductive sealants (electromagnetic shielding) Lubricants External tiles for submarine hulls Vibrational damping (engine and motor mounts) Electrical insulation Tires, belts, bushings, gaskets, seals Binders for propellants Foams Protective cover for hydraulic actuators... 

Lubricating processing aid Internal lubricant External lubricant UV light absorber Stabilizer... 

Containers stabilized with nontoxic calcium/zinc powders are popular in applications where opacity or translucency is acceptable. (Here nontoxic is used in a commercial sense, denoting a low order, not absence, of toxicity.) In these cases, the stabilizer, used at a level of 1.0-1.5 phr, serves as internal lubricant. External lubrication is provided by OPE wax as above. The remainder of the lubricant system is often 0.5-1.0 phr GMS or blends of GMS with montanic acid esters. 

By far the most common lead salt used for PVC stabilization is tribasic lead sulfate. It can be found either alone or combined with another lead salt in almost every lead-stabilized PVC formulation. Many of the combinations are actually coprecipitated hybrid products, ie, basic lead sulfophthalates. Dibasic lead stearate and lead stearate are generally used as costabilizers combined with other primary lead salts, particularly in rigid PVC formulations where they contribute lubrication properties dibasic lead stearate provides internal lubrication and lead stearate is a good external lubricant. Basic lead carbonate is slowly being replaced by tribasic lead sulfate in most appHcations due the relatively low heat stabiHty of the carbonate salt which releases CO2 at about 180°C during PVC processing. 

This discussion refers to external plasticization only. Several theories, varyiag ia detail and complexity, have been proposed ia order to explain plasticizer action. Some theories iavolve detailed analysis of polarity, solubiHty, and iateraction parameters and the thermodynamics of polymer behavior, whereas others treat plasticization as a simple lubrication of chains of polymer from each other, analogous to the lubrication of metal parts by oil. Although each theory is not exhaustive, an understanding of the plasticization process can be gained by combining ideas from each theory, and an overall theory of plasticization must include all these aspects. 

Poly(ethylene terephthalate). PET is a crystalline material and hence difficult to plasticize. Additionally, since PET is used as a high strength film and textile fiber, plasticization is not usually required although esters showing plasticizing properties with PVC may be used in small amounts as processing aids and external lubricants. Plasticizers have also been used to aid the injection mol ding of PET, but only at low concentrations. 

The success of the compaction operation depends pardy on the effective utilization and transmission of appHed forces and pardy on the physical properties and condition of the mixture being compressed. Friction at the die surface opposes the transmission of the appHed pressure in this region, results in unequal distribution of forces within the compact, and hence leads to density and strength maldistribution within the agglomerate (70). Lubricants, both external ones appHed to the mold surfaces and internal ones mixed with the powder, are often used to reduce undesirable friction effects (71). For strong compacts, external lubricants are preferable as they do not interfere with the optimum cohesion of clean particulate surfaces. Binder materials maybe used to improve strength and also to act as lubricants. 

Substituted Amide Waxes. The product of fatty acid amidation has unique waxlike properties (13). Probably the most widely produced material is N,1S7-distearylethylenediarnine [110-30-5] which has a melting point of ca 140°C, an acid number of ca 7, and a low melt viscosity. Because of its unusuaHy high melting point and unique functionaHty, it is used in additive quantities to raise the apparent melting point of themoplastic resins and asphalts, as an internal—external lubricant in the compounding of a variety of thermoplastic resins, and as a processing aid for elastomers. 

The principal appHcations for metal soaps are as heat stabili2ers and lubricants (both internal and external) in plastics, and as driers in paint and printing inks. 

Fretting corrosion (36,37) can lead to high contact resistance of base metal contacts, such as tin plate in electronic connectors. Small cycHcal displacements of the connector halves occur because of external vibration or differential thermal expansion and contraction of the mating contacts. The wear debris that is formed remains in the contact zone. The accumulation of oxide debris in the contact region leads to increased contact resistance. Solutions to this problem are stmctures that do not permit movement of contact surfaces with respect to one another, the use of gold as a contact finish, and the appHcation of thick coatings of contact lubricants and greases, which reduce the rate of wear and restrict access of air to the contact surfaces. 

Opening the suc tion valves by some external force (oil from the lubricating system, discharge gas, electromagnets. . . ). 

Environment Internal Lubricating oii, 300°F (150 C) External Treated cooling water, 176 F (80°C)... 

Lubrication is splash type and grease is used on the more competitive models. There are variations available with internal pressure lubrication systems. Some models can be equipped with an external lube system, and for rare cases, API 614 lubrication systems have been proposed. 

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