Surface Resin Friction Polymer

The aromatic radical anion can react with metal or metal oxide to form lower-valent metal oxide or metal wear particles. Surface resin (as Goldblatt prefers to call it) is formed from the aliphatic or naphthenic constituents by the following process  

Aromatic Radical Anion + White Oil— Adduct + Polymeric Resin 

Oxidation works on the aromatic radical anion and its combination with white oil as shown below  

Aromatic Radical Anion + White Oil + 0 ---------- Acids (aliphatic) + Resins 

In the presence of aliphatic or naphthenic material, surface resin is formed by the action of the aromatic radical anion in preference to 

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When a chemically deposited film of "friction polymer" or "surface resin" derived from precursors intrinsically part of a petroleum oil acts as an additive in the high-pressure lubricant behavior of that oil, then the function of the oil must be viewed in a two-fold light. That part of the oil which generates the surface film is in effect an additive. The rest of the oil is the inert liquid carrier. 

Composite Particles, Inc. reported the use of surface-modified rubber particles in formulations of thermoset systems, such as polyurethanes, polysulfides, and epoxies [95], The surface of the mbber was oxidized by a proprietary gas atmosphere, which leads to the formation of polar functional groups like —COOH and —OH, which in turn enhanced the dispersibility and bonding characteristics of mbber particles to other polar polymers. A composite containing 15% treated mbber particles per 85% polyurethane has physical properties similar to those of the pure polyurethane. Inclusion of surface-modified waste mbber in polyurethane matrix increases the coefficient of friction. This finds application in polyurethane tires and shoe soles. The treated mbber particles enhance the flexibility and impact resistance of polyester-based constmction materials [95]. Inclusion of treated waste mbber along with carboxyl terminated nitrile mbber (CTBN) in epoxy formulations increases the fracture toughness of the epoxy resins [96]. 

Additions of BN powder to epoxies, urethanes, silicones, and other polymers are ideal for potting compounds. BN increases the thermal conductivity and reduces thermal expansion and makes the composites electrically insulating while not abrading delicate electronic parts and interconnections. BN additions reduce surface and dynamic friction of rubber parts. In epoxy resins, or generally resins, it is used to adjust the electrical conductivity, dielectric loss behavior, and thermal conductivity, to create ideal thermal and electrical behavior of the materials [146]. 

Organic photoreceptors can be prepared in either a flexible web or drum format. Webs are usually prepared on polymer substrates, polyethylene tere-phthalate being the most common. The substrates are between 100 to 200 pm in thickness and coated with a conducting surface layer. The substrates often contain layers on the reverse side for reduced curl, static discharge prevention, and control of frictional characteristics. The web configuration is also widely used for laboratory studies. For drums, the substrate is a metal cylinder, usually Al. Recently, however, drums of a poly(phenylene sulfide) resin doped with conductive C black have been developed (Kawata and Hikima, 1996). Drums are widely used in low- and mid-volume applications. Drums, however, are not well suited for research purposes. Thus, the preparation and characterization of drum photoreceptors is usually related to a specific application. 

The heat to melt the resin comes from feed preheating, barrel and die heaters frictional heat. The frictional heat because of the rotation of the screw accounts for > 50% of energy input. Barrel and die heaters resistance heaters 5 to 6 W/cm of inner barrel surface. Power to covey and heat 0.4 to 1 kW s/g or 400-1800 kj/kg depending on screw design and polymer processed. 

Lubricants may be internal (incorporated into the host resin during production or compounding) or external (placed between the sliding surfaces before or during operation). Addition of PTFE to host polymers such as polyamide, polyacetal, polyphenylene sulphide, and PETP polyester considerably reduces their friction coefficients. Internal lubrication is not always the answer, however. In some cases (such as polyamide with 2 wt% silicone oil sliding against steel at a moderate speed and a low load), internal lubrication has been observed actually to increase friction. 

The frictional properties of thermoplastics, specifically the reinforced and filled composites, vary in a way that is unique from metals. In contrast to metals, even the highly reinforced resins have low modulus values and thus do not behave according to the classic laws of friction, as developed by theories from the ICI-LNP. Metal-to-thermoplastic friction is characterized by adhesion and deformation resulting in frictional forces that are not proportional to load, because friction decreases as load increases, but are proportional to speed (see Tables 3-21 through 3-24) [323]. The wear rate is generally defined as the volumetric loss of material over a given unit of time. Several mechanisms operate simultaneously to remove material from the wear interface. However, the primary mechanism is adhesive wear, which is characterized by having fine particles of polymer removed from the surface. 

The friction forces develop between the polymer surface and the surface of the mold, which is usually made of steel [26]. Also, it depends on resin and mold used, and the non-linear, distributed and time varying process dynamics. Manipulating the machine settings and process dynamics is necessary to control process variables [27]. 

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