Reinforcement additives

The term s plastic, polymer, resin, elastomer, and reinforced plastic (RP) are some-what synonymous. However, polymer and resin usually denote the basic material. Whereas plastic pertains to polymers or resins containing additives, fillers, and/or reinforcements. Recognize that practically all materials worldwide contain some type of additive or ingredient. An elastomer is a rubberlike material (natural or synthetic). Reinforced plastics (also called composites although to be more accurate called plastic composites) are plastics with reinforcing additives, such as fibers and whiskers, added principally to increase the product s mechanical properties. 

The styrenic thermoplastic elastomers are the only type which are fully compounded in the manner of conventional elastomers. In this case, however, the addition of carbon black, or other fillers, does not give reinforcement. Additions of polystyrene, or high impact polystyrene, and oil are used to vary hardness and tear strength, and fillers can be used to cheapen the material. Other added polymers, e g., EVA, can be used to increase ozone resistance. These materials also require antioxidants for protection during processing and service life, and the poor UV stability restricts their use in outdoor applications. 

A broad choice of lubricating and reinforcing additives leads to a good range of coefficients of friction, from 0.1 up to 0.3 for the static coefficients, and low wear from excellent to good. For example, static and dynamic coefficients of friction are, respectively ... 

The Schedule-Controlled Operant Behavior test guideline (OPPTS 870.6500) defines procedures for conducting studies of schedule-controlled operant behavior, one way of evaluating the rate and pattern of a class of learned behavior. The purpose of the guideline is to evaluate the effects of acute and repeated exposures on the rate and pattern of responding under schedules of reinforcement. Additional tests may be necessary to completely assess the effects of any substance on learning, memory, or behavioral performance. 

PTFE powder can be incorporated as a reinforcing additive in different rubber matrixes if enhanced mechanical, friction, and wear properties are desired. However, the different friction, wear, and chemical coupling mechanisms in... 

Both hydrated and anhydrous metal borates have numerous industrial uses. Some of the major uses of hydrated metal borates are the manufacture of glasses, ceramics, and industrial fluids, and as micronutrient fertilizers, fire retardants, and biostats. Anhydrous borates find use as heterogeneous catalysts, scintillation hosts, and in the fabrication of optoelectronic devices. Anhydrous aluminum borates are used as additives in oxide ceramics to promote the formation of desirable phases. Also, aluminum borate whiskers are used as reinforcing additives in composite materials. Specific nses of sodium, calcium, zinc, and barium borates are discussed in sections below. 

Elastomers are prepared by chain extension of hydroxyl-terminated low-molecular-weight polymers followed by vulcanization 180). The most important work concerns the use of hydroxy telechelic polybutadienes and polyisoprenes in the tire industry 249 252>. The hydroxylated polydienes of molecular weight 1000-20000 are mixed with a diisocyanate, a catalyst, vulcanization agent (sulfur), and accelerator, reinforcing additives (carbon black), and surface-active agents. The reaction takes place in two steps simultaneously or consecutively ... 

For electrostatic and steric stabilization, the particles can be viewed effectively as colloids consisting of a soft and deformable corona surrounding a rigid core. Colloidal particles with bulk elastomeric properties are also available. These particles, which are generally of submicron size, are developed and used as reinforcement additives to improve the Impact resistance of various polymer matrices [28-30]. The rubber of choice is often a styrene/butadiene copolymer. The presence of chemical groups at the matrix-filler interface leads to improved adhesion between them. Typically, the addition of about 30% by volume of these elastomeric particles increases the impact strength of a brittle glassy polymer like polystyrene by up to a factor of 10. For some applications, particles with more complex architecture have been... 

The two components are kept in temperature-controlled tanks, with pumped re-circulation when injection is not taking place. For the polyurethane system, one tank contains an isocyanate (usually MDI) and the other a mixture of polyol, chain extenders, catalyst and mould release (and possibly blowing agent or reinforcing additives). An amine catalyst accelerates the initiation of the polymerisation, while an organotin catalyst... 

A wide variety of additives is used with both TS and TP resins to adjust the handling, processing, property, and/or simply to add bulk and reduce cost without impairing the properties of RPs. Cost-reduction is not always the end-result. Apart fi om reinforcement, additives for these resins are generally in the form of particles or liquids, or combinations of the two, such as pastes (Chapters 3 and 4). Generally, the particles influence the mechanical properties, while the liquids are reactant components. Colorants can take the form of powders, pastes or liquids. In addition to what follows in this section more follows in his chapter and throughout this book. 

What are the most dramatic ways in which reinforcing additives are used to improve mechanical properties ... 

When properties are more of a concern, lower-cost fillers also can act as extenders that displace not resin, but rather higher-cost reinforcing additives. For example, wollastonite can sometimes partially or fully replace more expensive, milled glass filler, or partially replace chopped glass fibers, while providing similar mechanical properties [7-6, 7-13]. 

The thermal stability of high-temperature plastics can be further enhanced by reinforcing additives. Such reinforced high-temperature plastics are used in rocket construction techniques where short-term heavy thermal attack needs to be resisted (the nose of a rocket, liner of the nozzle, etc.). Undergoing this load, a part of the polymer is consumed either by volatilization or by carbonization, resulting in a protection of the subjacent layers from thermal effects. This consumption of the polymer by virtue of a short-term exposure to a very high temperature is called ablation. 

These examples illustrate the important principles of potymer reinforcement. A good reinforcing additive has the following attributes ... 

Carbon black as a reinforcing additive has been employed in rubber manufacture for many years. One may argue that carbon black provides nanoparticle reinforcement for rubber. There are many reviews available on carbon black use in rubber.[46] We will focus on recent advancements in nanoparticle reinforcement. These advancements do not include carbon black. Most of the recent advancements in nanoparticle reinforcement in rubber have focused on montmorillonite clay.There are several reviews on rubber... 

WITH the easy-processing properties in the liquid crystalline phase, main-chain TLCPs have been widely used as high-strength fiber, fiber reinforcement, in situ reinforcement additive, and injection molded articles, etc, [ 1 -4]. The successful applications are quite dependent on the adhesion at interface of the liquid crystalline polymer and the conventional engineering resin, which is indeed affected by surface tension and/or interfacial tension between the two phases [1-2],... 

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