Surface, surfaces gloss

Many mbber-modified styrene plastics are fabricated into sheet by extmsion primarily for subsequent thermoforming operations. Much consideration has been given to the problem of achieving good surface quaUty in extmded sheet (230,231). Excellent surface gloss and sheet uniformity can be obtained with styrene-based polymers. 

PPS resins are chiefly used for injection mol ding. The melt flow of the glass-fiUed resins is very stiff, and high injection pressures are required. Mold surface wear is heavier than for most other engineering plastics. Mol ding melt temperatures are near 330°C for optimum surface gloss and impact strength, mold temperatures of 130°C should be used. The resins are brown to brown-black. 

A further class of ethylene-vinyl acetate copolymer exists where the vinyl acetate content is of the order of 3 mole %. These materials are best considered as a modification of low-density polyethylene, where the low-cost comonomer introduces additional irregularity into the structure, reducing crystallinity and increasing flexibility, softness and, in the case of film, surface gloss. They have extensive clearance as non-toxic materials. 

Polyethylene terephthalate is injection blow molded to make water and carbonated drink bottles, and other liquid food packages. High stiffness, excellent clarity, and good resistance to carbon dioxide permeation are the principal attributes of these bottles. We carefully control molding conditions to promote transparency and surface gloss, which are prized for food... 

Rubber toughened polystyrene is widely used in electronic and kitchen appliances. This type of application requires a good balance of stiffness, impact resistance, and ready coloration. Telephones, which are frequently dropped, are an excellent example of the benefits of rubber toughened polystyrene. The high surface gloss that we desire is obtained by minimizing the size of the rubber particles. Larger items, such as canoes, can be thermoformed from extruded sheet. 

Edwards, S. A. and Choudhury, N. R., Variations in Surface Gloss on Rubber-Modified Thermoplastics Relation to Morphological and Rheological Behavior, Polym. Eng. Set, 44, 96 (2004)... 

Cellulose esters are used as plastics for the formation by extrusion of films and sheets and by injection molding of parts. They are thermoplastics and can be fabricated employing most of the usual techniques of (largely compression and injection) molding, extrusion, and casting. Cellulose ester plastics are noted for their toughness, smoothness, clarity, and surface gloss. 

The reinforcement can also cause increases in hardness and abrasion resistance, along with decreases in creep and dimensional changes with humidity. Undesirable effects brought on by the addition of glass reinforcement include opacity, low surface gloss, some difficulty in electroplating, and loss of mechanical flexibility. 

The visual appearance and optical properties of a material depend on its color and additives, etc., as well as on the nature of its surface. Gloss is a term employed to describe the surface character of a material which is responsible for luster or shine, i.e., surface reflection of a polymeric material. 

ABS products with high impact strengths and relatively high surface gloss may be produced by using traditional emulsion polymerization techniques. 

Similar results are obtained with copolymers of vinyl acetate, acrylates, and maleates. The addition of small amounts of liquid plasticizers improves the surface gloss and smoothness of the films. The brittle point is excellent, and it is possible to get values down to — 62°C. with 40 to 45% of the plasticizer combination. 

Fig. 7.4 Surface gloss under room light illumination (a) Ti02-free substrate with a UV intensity of 0.12 mW cm-2 (b) and (c) Ti02- coated substrate with UV intensities of 0.12 mW cm-2 and 3.5 mW cm-2, respectively. The initial value of each case was normalized to one.

Next, we report the anti-fouling effect.33-37) The anti-fouling effect has been confirmed only qualitatively. The time course change of surface gloss of the substrates was measured by a commercial gloss meter A self-cleaning function can also be expected with TiO -coated substrates when small amounts of organic... 

Surfaces of spacecraft in low earth orbits (200-600 km) often undergo damage (253, 254), the severity of which is a function of the type of material. Organic polymers and carbon surfaces are the most severely damaged and may even disappear altogether. Some metal films, such as osmium, are also known to disappear, whereas others, such as silver, are severely oxidized. Painted surfaces lose gloss and become pitted (255). 

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