Zinc oxide reinforcement

Silicic add, Terpene resin. Zinc oxide reinforcing agent, acrylates WackerHDK H15 reinforcing agent, acrylics Translink HF-900... 

EFFECT OF ZINC OXIDE REINFORCEMENT ON ELECTRICAL PROPERTIES OF POLYMERS... 

Other Reinforcement Ma.teria.Is. Other materials that have been used in tire compounds for reinforcement are chopped wire (brass-coated), cotton and nylon flock, chopped nylon strands, polyethylene, zinc oxide, and chopped Kevlar. Most of these materials have very limited apphcation and some are obsolete. Others are used more extensively in soHd mbber industrial tires than in pneumatics. 

For equivalent particle size the carbon blacks are the most powerful reinforcing fillers. However, fine particle size silicas can be very useful in non-black compounds whilst other fillers such as aluminium hydroxide, zinc oxide and calcium silicate have some reinforcing effect. 

The pneumatic tire has the geometry of a thin-wallcd toroidal shell. It consists of as many as fifty different materials, including natural rubber and a variety ot synthetic elastomers, plus carbon black of various types, tire cord, bead wire, and many chemical compounding ingredients, such as sulfur and zinc oxide. These constituent materials are combined in different proportions to form the key components of the composite tire structure. The compliant tread of a passenger car tire, for example, provides road grip the sidewall protects the internal cords from curb abrasion in turn, the cords, prestressed by inflation pressure, reinforce the rubber matrix and carry the majority of applied loads finally, the two circumferential bundles of bead wire anchor the pressnrized torus securely to the rim of the wheel. 

One of the most important phenomena in material science is the reinforcement of mbber by rigid entities, such as carbon black, clays, silicates, calcium carbonate, zinc oxide, MH, and metal oxide [45 7]. Thus, these fillers or reinforcement aids are added to mbber formulations to optimize properties that meet a given service application or sets of performance parameters [48-53]. Although the original purpose is to lower the cost of the molding compounds, prime importance is now attached to the selective active fillers and their quantity that produce specific improvements in mbber physical properties. 

Attempts have been made to improve the mechanical properties of these cements by adding reinforcing fillers (Lawrence Smith, 1973 Brown Combe, 1973 Barton et al, 1975). Lawrence Smith (1973) examined alumina, stainless steel fibre, zinc silicate and zinc phosphate. The most effective filler was found to be alumina powder. When added to zinc oxide powder in a 3 2 ratio, compressive strength was increased by 80 % and tensile strength by 100 % (cements were mixed at a powder/liquid ratio of 2 1). Because of the dilution of the zinc oxide, setting time (at 37 °C) was increased by about 100%. As far as is known, this invention has not been exploited commercially. 

In a further attempt to improve properties, Brauer, McLaughlin Huget (1968) examined the use of alumina as a reinforcing filler. Alumina is considerably more rigid than fused quartz. They achieved a considerable increase in strength. The preferred composition was the powder defined in Table 9.4, which had a compressive strength of 91 MPa. This zinc oxide based powder was the one most commonly used in subsequent studies by Brauer and coworkers. We shall refer to it as the EBA powder for it is the one used in commercial formulations and in a number of experimental studies. 

Brauer, G. M., McLaughlin, R. Huget, E. F. (1968). Alumimun oxide as a reinforcing agent for zinc oxide eugenol-o-ethoxybenzoic acid cements. 

Civjan, S., Huget, E. F., Wolfhard, G. Waddell, L. S. (1972). Characteristics of zinc oxide eugenol cements reinforced with acrylic resin. Journal of Dental Research, 51, 107-14. 

Silvey, R. G. Myers, G. E. (1976). Clinical studies of dental cements. VI. A study of zinc phosphate EBA-reinforced zinc oxide eugenol and polyacrylic acid cements as luting agents in fixed prostheses. Journal of Dental Research, 56, 1215-18. 

The shift in the C=C frequency, vi, for adsorbed ethylene relative to that in the gas phase is 23 cm-1. This is much greater than the 2 cm-1 shift that is observed on liquefaction (42) but is less than that found for complexes of silver salts (44) (about 40 cm-1) or platinum complexes (48) (105 cm-1). Often there is a correlation of the enthalpy of formation of complexes of ethylene to this frequency shift (44, 45). If we use the curve showing this correlation for heat of adsorption of ethylene on various molecular sieves (45), we find that a shift of 23 cm-1 should correspond to a heat of adsorption of 13.8 kcal. This value is in excellent agreement with the value of 14 kcal obtained for isosteric heats at low coverage. Thus, this comparison reinforces the conclusion that ethylene adsorbed on zinc oxide is best characterized as an olefin w-bonded to the surface, i.e., a surface w-complex. 

Compounding ingredients which bring about reinforcement of rubbers. The most widely used are carbon black, silica and silicates, zinc oxide, treated whitings, high styrene resins and phenolic resins. 

Applied to certain compounding ingredients (particularly zinc oxide and precipitated whiting) which have been surface-treated to improve their reinforcing power or their ease of incorporating into rubber. Also applied to a lining which has... 

An activator in rubber compounds containing organic accelerators. In polychloroprene, zinc oxide is considered to be the accelerator rather than the activator. The use of zinc oxide as a reinforcing agent and as a white colouring agent is obsolescent. Zinc oxide is manufactured by either the French (or indirect) process or by the American (or direct) process. It can be used as a filler to impart high thermal conductivity. 

Although, because of its cost, titanium dioxide is usually only used as a whitening agent for rubber compounds, it is in fact a reinforcing agent comparable on a volume basis with the reinforcement found with zinc oxide. 

The basic compounding formulation specifies the minimum requirement of fillers, vulcanizing agents, and other substances that must be added to the rubber compound to achieve the desired properties. After the rubber, cure system and reinforcing filers have been selected it will be necessary to make several adjustments before all requirements are satisfied. It is generally sensible to start with the simplest mix formula for meeting the requirements. The recipe or the formula is usually written on the basis of hundred parts of rubber. For example if 5 parts of zinc oxide is to be added it is denoted as 5 phr (five parts per hundred rubber). Elementary compounding... 

Fluorosilicones can be compounded by the addition of mineral fillers and pigments. Fillers for such compounds are most commonly silicas (silicon dioxide), because they are compatible with the elastomeric silicon-oxygen backbone and thermally very stable. They range in surface areas from 0.54 to 400 m2/g and average particle size from 100 to 6 nm. Because of these properties, they offer a great deal of flexibility in reinforcement. Thus, cured compounds can have Durometer A hardness from 40 to 80. Other fillers commonly used in fluorosilicones are calcium carbonate, titanium dioxide, and zinc oxide. 

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