Frame plating method

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. 

For open filters, use alternate closed filtering methods such as plate and frame... 

In the true gravity case, pumps are not used. If, however, the liquid is highly viscous, to achieve efficient operation, pumps are required to force the fluid through the pressure filters. The pump can be considered essentially as a press with a plate-and-frame filter. The plate-and-frame filter consists of a series ot frames over which the filter medium is stretched. A centrifugal basket of fine mesh is another method of particulate removal. 

Demountable cells can be disassembled and may or may not use a spacer. Without a spacer, the liquid sample is simply applied to one salt plate, and the second plate is positioned over the first to smear the liquid out between the plates. Such a method cannot be useful for quantitative analysis because the pathlength is undefined and not reproducible. Also, the two salt plates may be positioned in the path of the light without a frame if there is a way to hold them there. If a spacer is used, it is positioned over one of the plates. The sample is applied to this plate in the cutout space in the spacer reserved for it, and the second plate is then positioned over the first with both spacer and sample in between. There are no inlet and outlet ports since the sample is not introduced that way. However, the plates, with sample, are placed in a frame, or holder, similar in appearance to the sealed cell, but without the ports. See Figure 8.18. Such a cell is also undesirable for quantitative analysis because of the difficulty in obtaining an identical pathlength each time the cell is reassembled. 

If both electrodes have to be made of materials, that are available only as foils or sheets or are not machinable, or for example, for materials, such as graphite felt, a cell design like the one in Fig. 9 is not realizable. Inlet and outlet systems have to be integrated in the electrolyte compartments. The parallel-plate and frame design of a laboratory flow-trough cell in Fig. 10 consists of easy-to-produce parts, using the fixing method for PTFE tubes in Fig. 4. 

Materials and Methods. The isomeric compositions of the four polybutadienes used are listed in Table I. Samples were prepared for infrared measurement from solutions of the polymer without further purification. Most films were cast from carbon disulfide solutions on mercury or on glass plates, but a few films were cast from hexane solutions to determine whether or not the solvent affected the radiation-induced behavior. No difference was observed for films cast from the different solvents. The films were cured by exposure to x-rays in vacuum. (Doses were below the level producing detectable radiation effects.) They were then mounted on aluminum frames for infrared measurements. The thicknesses of the films were controlled for desirable absorbance ranges and varied from 0.61 X 10 s to 2 X 10 3 cm. After measuring the infrared spectrum with a Perkin-Elmer 221 infrared spectrophotometer, the mounted films were evacuated to 3 microns and sealed in glass or quartz tubes (quartz tubes only were used for reactor irradiations). 

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