Polymer exposure sources

Fabricating microlenses with a dipping method. (1) Fluoropolymer thin film is deposited on the surface by dip coating. (2) In areas not protected with a photomask, polymer is decomposed by low wavelength UV radiation. (3) Polymer solution is transferred onto hydrophilic spots using a needle printer. (4) After evaporation of solvent, the polymer is cross linked in a UV flood exposure. Source Dorrer, C., O. Prucker, and J. Riihe. 2007. Advanced Materials, 19(3), 456. With permission.)... 

The excimer laser can function simply as an exposure source to effect a chemical change in the polymer film that subsequently can be developed out in a conventional manner. In addition, because of its high power, the laser can also be used to ablate the exposed areas directly and lead to self-developed images. The intensity of the excimer laser is such that almost any polymer can be made to undergo dramatic scission. The degraded fragments vaporize from the imaged area at the... 

The use of an ion beam as an exposure source is a relatively new development, which has found use in repairing expensive photomasks and has been shown to have the capability of exposing resists to produce submicron features. The polymeric resists used for ion beam lithography are generally those that are used for e-beam lithography. The mass of the ions and the very high accelerating potentials combine to mean that almost any polymer will scission or cross-link when exposed to a... 

Exposure to PTFE can arise from ingestion, skin contact, or inhalation. The polymer has no irritating effect to the skin, and test animals fed with the sintered polymer have not shown adverse reactions. Dust generated by grinding the resin also has no effect on test animals. Formation of toxic products is unlikely. Only the heated polymer is a source of a possible health hazard (120). 

Figure 5.JO Relative stabilities of various polymers to exposure by high-energy sources. (After...

Occupational and environmental exposure to chemicals can take place both indoors and outdoors. Occupational exposure is caused by the chemicals that are used and produced indoors in industrial plants, whereas nonoccupa-tional (and occupational nonindustrial) indoor exposure is mainly caused by products. Toluene in printing plants and styrene in the reinforced plastic industry are typical examples of the two types of industrial occupational exposures. Products containing styrene polymers may release the styrene monomer into indoor air in the nonindustrial environment for a long time. Formaldehyde is another typical indoor pollutant. The source of formaldehyde is the resins used in the production process. During accidents, occupational and environmental exposures may occur simultaneously. Years ago, dioxin was formed as a byproduct of production of phenoxy acid herbicides. An explosion in a factory in... 

It has been estimated that over 100,000 workers are potentially exposed to acrylonitrile during production and use (NIOSH 1977, 1988). Occupational exposures include plastic and polymer manufacturers, polymer molders, polymer combustion workers, furniture makers, and manufacturers of fibers and synthetic rubber (EPA 1980a). Other populations who could have elevated exposure to acrylonitrile are residents in the vicinity of industrial sources or chemical waste sites. 

An industrial standard method has been developed to test the lightfastness of polymers in accelerated test equipment [103]. The apparatus consists of a quartz-xenon tube with a special optical filter between the light source and the specimen to produce light that resembles window glass-filtered daylight [104], Samples are mounted at a specific distance from the arc and are supported on a frame which revolves around the arc 1 to 5 times per minute for uniform exposure. A blower unit in the base provides a flow of air which makes it possible to maintain a black panel temperature of 45°C, measured by a black panel thermometer which is positioned at level with the samples. A black panel unit consists of a bimetallic thermometer mounted on a steel frame. Both faces of the frame plate and also the stem of the thermometer are coated with a heat-resistant glossy black enamel. The relative humidity level in the exposure cabinet is closely controlled. 

Polymers are organic materials and are sensitive to natural or artificial UV sources. This is of primary importance for outdoor exposure of unprotected parts and for some industrial applications such as electrical welding, photocopier light exposure devices. .. 

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