Surface-treatment

The treatments to improve fiber-matrix adhesion includes chemical modification of the lignocellulosic (anhydrides, epoxies, isocyanates, etc.), grafting of polymers onto the lignocellulosic and use of compatabilizers and coupling agents [38]. 

Various treatment methods onto oil palm fibers are already discussed in detail [22, 23, 45-47] including a detailed discussion on various treatments on lignocellulosic fibers in general to improve their properties [48]. Reviews on the developments in chemical modification and characterization of natural fiber-reinforced composites 

Mercerization Amorphous waxy cuticle layer leaches out. 

Latex coating Partially masks the pores on the fiber surface. 

Y irradiation Partially eliminates the porous structure of the fiber and causes microlevel disintegration. It degrades mechanical properties considerably. 

Surface treatments are applied to new structures as a preventative measure, to existing structures where the need for future protection is anticipated, and to repaired structures in order to improve the service life of the repairs (as well as to mask the visible effect of repairs). Of the many types of surface treatment of concrete, only those aimed at providing protection against corrosion of reinforcement will be mentioned here. This places coatings for protection against chemical attack outside the present scope. 

Surface treatments are, generally, mechanical operations giving the final aspect to fabric surface. Pressing (ironing), raising, suing and shearing are, probably, the most important ones. 

These operations, particularly raising, suing and shearing, produce certain amounts of dust and fuzzy fibres as pollutants. 

While artificial fibres came onto the market with the 1889 invention of rayon by Hilaire de Chardonnet, and synthetic fibres emerged with the 1931 DuPont patent for Nylon, natural fibres have been around since the dawn of mankind, flax having a documented history (burial shrouds for the Egyptian pharaohs) of more than 7000 years. No matter in which climatic zone humans settled, they were able to find and utilize the fibres of native species to make products such as clothes, cloths, buildings and cordage. 

The modern composite materials, which merge the advantages of natural fibres with synthetic matrices and environmental goals, aim to go beyond the fibre competition during the last 100 years and to answer the new challenges. 

http //www.youthxchange.net/main/bl64 ffl textile-fibres-intro b.asp (retrieved 12.08.2008). 

Several techniques are in use within the plastics industry, including corona discharge, plasma etching, flame treating and the use of chemical primers to enhance surface energy. 

The technology of treating titanium dioxide pigments is thus very complex. Property differences arise from the type, thickness, combination and method of application of surface treatment, as shown in the following  

The original surface treatment, which is still the most popular, is alumina. Among other inorganics, silica is used less frequently and zirconium rarely. Inorganics are usually added to improve properties of the end product, but they also enhance slightly the dispersion characteristics. In addition, by forming a barrier between the titanium dioxide and the matrix resin, they inhibit undesirable chemical reactions. 

Alumina(aluminium oxide). This is used at levels from 0.5 to 3.5%, applied during manufacturing. It is compatible with all main resin systems, but can give problems by outgassing of its water of crystallization at elevated temperatures, the water vapour remaining as a pocket in the melt and finished product. In thin films this causes voids (known as lacing ). When processing at above 25()-3()0°C it is recommended to use particles with 0.5% alumina or below. 

Polyols and amines. These enhance wetting and dispersion in almost all polymer systems, giving broadly the same results (but polyol treatments are possibly better with vinyl compounds). 

Siloxanes. These give about the same performance as polyols and special grades are effective in retarding undesirable reactions in polycarbonates. In excessive proportions, however (above about 1%), siloxanes can separate from the Ti02 and migrate to the surface, affecting printability and sealing characteristics. 

Another consideration when assessing surface treatment costs is part size. There are some critical sizes for each surface-treatment process above which the cost of obtaining the treatment may be high. A number of surface treatments require that the part fit into the work zone of a vacuum chamber. The cost of vacuum equipment goes up exponentiahy with chamber volume. 

13% Cr wire Ni-Cr-B and fuse Ni-Cr-B + WC and fuse Surface weld Iron-base Cobalt-base Vapor deposited CVDTiC PVDTiN 

Environmentally related costs, for example, disposal of spent plating solutions 

Finally, chemical alteration of surfaces can improve adhesion. Semicrystalline materials have low polarity and low surface tension that must be increased to enable adhesives to bond. Oxidizing processes such as corona discharge, plasma, flame treatments, or UV irradiation in the presence of air or oxygen may be used to alter normally nonpolar surfaces, rendering them 

Teflon and other fluorocarbon surfaces may be altered by chemical treatments using solvent solutions of sodium naphthalene complex or molten sodium. Teflon etchants, for example, Tetra-Etch , a tradename and product of W. L. Gore Associates, are effective in improving adhesion to Teflon. Oxidation treatments for metals such as copper or aluminum also produce highly polar oxide surfaces that are more easily bondable. 

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The AET was used at standard tests of numerous structural materials, above all steels and cast iron, prepared are ceramic samples. Part of tested samples had qjecial sur ce layer treatments by laser, plasma nitridation and similar. Effect of special surface treatment the authors published already earlier [5,6]. In this contribution are summed up typical courses of basic dependencies, measured by the AET at contact loading. 

Institute, Sesimbra Portugal, "Laser Processing Surface Treatment and Film... 

Metals treatments Metal sulfides Metal surface cleaners Metal surface treatment Metal surface treatments... 

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