Plastic Spectacle Research Articles

Effects of cage shape, colony size, floor area and cannibalism preventatives on laying performance

1. Wire cages of variable width and depth, with a floor slope of 1 : 12, were used in two experiments to study the effects of cage depth, feeding space (= cage width), floor area, colony size and two methods of controlling cannibalism in White Leghorn x Australorp laying hens. 2. The least floor area (0.035 m2/bird) depressed production in two‐bird cages. Floor area had little effect on the performance of larger colonies. 3. Birds in colonies of three, four or six laid and survived equally well when feeding space/bird and floor area/bird were constant. 4. Production per hen d and food intake were higher, but return on estimated capital outlay was lower, with 102 mm than with 76 mm feeding space/bird when colony size and floor area/bird were constant. 5. Production and food intake of birds which were not treated to prevent cannibalism declined, and mortality increased, as cage depth increased from 385 to 915 mm concomitantly with increasing colony size from 2 to 7 birds and decreasing feeding space from 152 to 43 mm/bird. 6. Increasing cage depth did not increase the proportion of cracked eggs. 7. Mortality was higher among birds fitted with plastic spectacles than among debeaked birds.

New coating materials prepared by radiation‐induced polymerization. I. Mar‐resistant coating composition and properties

AbstractA mar‐resistant coating system was obtained by screening combinations of silicone and vinyl compounds. It was found that binary systems, such as the γ‐glycidoxypropyltrimethoxysilane–glycidyl methacrylate system, were excellent not only in mar resistance but also in adhesion to base resin polymers. Haze values of these coatings, after the sand‐falling test, reached less than 10%. The coating process consisted of three steps: the preparation of prepolymer, the coating to plastic surface, and the curing of the coating by heating. It was found that the prepolymerization step could be performed by irradiation very conveniently; the control of viscosity for coating application and thickness control could be possible without any gel formation. These coatings were also good in weather resistance due perhaps to the good adhesion to base resin and could be applicable to plastic spectacles, glazing materials, and a variety of other products.

What About Plastic Spectacle Lens?

What About Plastic Spectacle Lens?

Plastic spectacle lenses

Perspex, a polymer of methyl methacrylate, possesses all the attributes, except hardness, desirable in a material for spectacle lenses. It is especially resistant to impact and splintering and is extraordinarily light in weight. Experiments are described illustrating (a) that surface scratches, arising because of the relative softness of Perspex, are not so troublesome to vision as might be supposed; (b) the resilience and resistance to splintering of Perspex. The manufacture of plastic lenses, in which the lapping operations necessary with glass are replaced by a simple moulding operation, is briefly described. Plastic lenses for binoculars, telescopes and photography, as well as plastic spectacle lenses, are in production.