Rubbers, additives Fillers

The second path in Fig. 3 outlines the approach to a more robust tape designed by Drew [21]. Here the milled rubber and filler are combined with tackifiers and other additives/stabilizers in an intensive dispersing step, such as a Mogul or Banbury mixer. Next, a phenolic resin or an alternative crosslinker is added and allowed to react with the rubber crosslinker to a point somewhat short of crosslinking. The compounded mixture is then charged to a heavy duty chum and dissolved in a suitable solvent like mineral spirits. To prepare a masking tape. 

Elastomer-plastic blends without vulcanization were prepared either in a two roll mill or Banbury mixer. Depending on the nature of plastic and rubber the mixing temperature was changed. Usually the plastic was fed into the two roll mill or an internal mixer after preheating the mixer to a temperature above the melting temperature of the plastic phase. The plastic phase was then added and the required melt viscosity was attained by applying a mechanical shear. The rubber phase was then added and the mixture was then melt mixed for an additional 1 to 3 min when other rubber additives, such as filler, activator, and lubricants or softeners, were added. Mixing was then carried out with controlled shear rate... 

It has been well established that wear resistance of filled rubber is essentially determined by filler loading, filler morphology, and polymer-filler interaction. For fillers having similar morphologies, an increase in polymer-filler interaction, either through enhancement of physical adsorption of polymer chains on the filler surface, or via creation of chemical linkages between filler and polymer, is crucial to the enhancement of wear resistance. In addition, filler dispersion is also essential as it is directly related to the contact area of polymer with filler, hence polymer-filler interaction. 

At Goodyear laser-desorption MS has been used for direct analysis of rubber additives (e.g. antioxidants, antiozonants, vulcanising agents, processing oils, silica fillers, etc.), in situ at the surface of an elastomeric vulcanisate [74,75]. 

Fillers are materials that modify rubber characteristics (e.g., hardness) and improve its physical characteristics (e.g., tensile strength), in addition to reducing costs. Rubber is sometimes compounded without the use of fillers the resultant product is called gum rubber. Typical fillers are calcined and hydrated clays, magnesium silicate (talc), magnesium oxide, and silicas. Carbon black, a common filler used to increase the heat resistance in industrial components such as tires, is not used as a filler in pharmaceutical components but it is used in smaller amounts as a black pigment. Polynuclear aromatic (PNA) hydrocarbons are a concern with carbon blacks but the grades used by manufacturers of pharmaceutical components contain very low concentrations. 

In addition to black, the elastomer may be compounded with other common fillers such as silica, clay, and asbestos. However, in general, their reinforcing properties are inferior to carbon. For certain uses, it is advantageous to compound the rubber without fillers. This gum vul-canizate has poorer physical properties than loaded stock but is better in chemical resistance. Both reinforced and gum recipes may include perfluoro greases or oils as plasticizers to soften vulcanizates without affecting appreciably chemical resistance. 

As rubber has a much better coefficient of friction compared with polyoleflns, it might be helpful to add rubber powder or small particles into, say, HDPE-based composite matrix. Coarse grades of calcium carbonate could serve the same purpose (this would be again a certain trade-off in properties of the flnal composite material). Additional benefits can be obtained if the same additive/ filler enhances both friction and impact resistance (a rubber might be a good candidate in this case). 

Limera is a family of styrenic thermoplastic/ rubber compositions. The compositions are suitable for compounding with a variety of additives, fillers and polymers such as PS, PVC, PMMA, ABS and PPE. They are processable by injection molding, extrusion and blow molding. 

OTHER COMMENTS used as an additive to clay in ceramic manufacturing and paper coatings used as a filler in paints, putty, plaster, oilcloth, slate pencils, and crayons formerly used in dusting powder, either alone or with starch or boric acid also used as a pigment in paints, varnishes, and rubber, a filler for paper, rubber, and soap useful as a glove and shoe powder has also been used as an electric and heat insulator. 

We used a new silane which readily permits quantitative conversion of silanol-terminated fluids into aminopropyl-terminated fluids. The reaction between aminopropyl-terminated fluids and diisocyanates proceeds smoothly within a few minutes, either in solution or in the melt. The preparation of siloxane-urea block copolymers is performed in either a two- or a three-component process. By carefrilly choosing the inorganic segment defined by the corresponding silicone fluid, it is possible to obtain silicone rubbers with different material characteristics. The mechanical properties can be tuned from very soft to very hard. Those materials display tensile strengths up to 14 MPa without requiring additional fillers and crm be used for diverse applications. 

In addition to their use on highways and roofs, both hot poured and room temperature hardening bituminous compositions have been used as caulking materials and sealants in building construction. The classical agphalt/ashestos sealants contained volatile solvents and their resistance to solvents was increased by the incorporation of coal tar. These sealants have also been modified by the addition of elastomers, such as powdered rubber, and fillers, such as sawdust.12... 

As stated previously, styrene-diene triblock copolymers are the most important category of thermoplastic elastomers. Unlike most other TPEs, they can be blended with large quantities of additives without a drastic effect on properties. In almost all applications, the actual triblock copolymer content is less than 50%. Oils are used as a processing aid and do not result in a significant loss of properties if the polystyrene domains are not plasticized. For this reason, naphthalenic oils are preferred. The use of inert fillers such as clays or chalks reduces the cost of the final material. Unlike conventional rubbers, inert fillers do not have a substantial effect on the mechanical properties of TPEs. Thermoplastics such as polyethylene or polypropylene are also used to improve the solvent resistance and can increase the upper service temperature. Polystyrene homopolymer is used as a processing aid, which also increases the hard phase weight fraction and causes the material to stiffen. 

The terms plastic, polymer, resin, elastomer, and RP are somewhat synonymous. Plastic and resin are interchangeable. Worldwide the term preferred is plastic for URP and resin for RP. Polymer denotes the basic material. Whereas plastic pertains to polymers or resins (as well as elastomers, RPs, etc.) containing additives, fillers, and/or reinforcements. An elastomer is a rubber like material (natural or synthetic). RPs (also called plastic composites) are plastics with reinforcing additives such as fibers and whiskers, added principally to increase the product s mechanical properties. 

CAS 1317-33-5 EINECS/ELINCS 215-263-9 Uses Dry lubricant on surfaces lubricant in rubber extrusions filler in self-lubricating plastics and powd. metal parts additive in metalworking compds. can act as coating if mixed with binder Properties Blue-gray slippery powd. 0.4-0.45 p particle size m.w. 160.06 ... 

This is one of the most important synthetic thermoplastic elastomers. Nitrile rubber is a copolymer of butadiene and acrylonitrile. The copolymer usually contains enough acrylonitrile (>25%) so that good resistance to oil and grease can be obtained. Adhesive properties also increase with increasing nitrile content. These adhesives are used to bond vinyls, other elastomers, and fabrics where good wear, oil, and water resistance are important. Compatibility with additives, fillers, and other resins is another advantage of this material.Table 5.1 summarizes the properties of nitrile rubber. 

Up until World War II, almost all elastomers were based on natural rubber. During the war, synthetic rubbers began to replace the scarce natural rubber. Since that time production of synthetics has increased until it now far surpasses that of natural rubber. There are thousands of different elastomer compounds. Not only are there many different classes of elastomers, but also individual types can be modified with a variety of additives, fillers, and reinforcements. In addition, curing temperatures, pressures, and processing methods can be varied to produce elastomers tailored to the needs of specific applications. 

There may be a combination of inert mineral fillers used in the rubber formulation to reinforce the rubber. Additionally, the primary cure, accelerator, and activator would be considered the cure system for the formulation. 

From the data of the kinetics of vulcanization (fiber content—2% for all samples) we know that the addition of the fibers, which was obtained on cobalt catalyst regardless of laundered or not it reduces the induction period and the cure time, but fiber, washed from the metal, not much increase the viscosity of the technology (Table 2 of Section 5.1, Fig. 2 of Section 5.1). As we can see from the data on swelling, samples containing fiber swell more than rubber without filler, it s indicative of a lower density of chemical bonds in the vulcanizates containing fiber. 

Glass transition temperature, crystallinity, cross-linking, fiber fillers, plasticizers Molecular weight, chain orientation, reinforcement, rubber additions Molecular motion, reactive groups Free motion of electrons... 

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