Hard rubber | 150-190 | | Do. Casein | | 200 | Cellulose compounds: | | | Ethyl cellulose | | 210-266 | Cellulose acetate sheet | 140-230 | 122-212 | Do. Cellulose acetate molding | 145-260 | 122-212 | Do. Cellulose nitrate | 160-195 | | -----------------------------------+-----------+------------+----------- NOTE.—The values for the properties in this table are based upon maximum and minimum figures submitted to Modern Plastics by a number of manufacturers of each type of material. Differences in test procedures and sizes of test specimens may lead to erroneous conclusions in some cases if direct comparisons are attempted. Special grades of materials are often available which excel in one particular property. Source: Modern Plastics, vol. 15, No. 2, opp. p. 120. October 1937. TABLE 21.—_Synthetic resins and other plastics: Electrical properties_ ----------------------------------+-------------------+---------------- |Volume resistivity | Breakdown | (50 percent | voltage, 60 Type |relative humidity) | cycles (volts | (ohm = cms) | per mil | |(instantaneous)) ----------------------------------+-------------------+---------------- Synthetic resins: | | Tar-acid—Formaldehyde: | | Molded, wood flour filler |10¹⁰-10¹² |300-500 Molded, mineral filler |10⁹-10¹¹ |250-400 Molded, fabric filler |10⁹-10¹¹ |300-450 Laminated, paper base |10¹⁰-10¹³ |400-1,300 Laminated, fabric base |10¹⁰-10¹² |150-600 Laminated, asbestos cloth base| |90 Cast |10⁹-10¹⁴ |300-450 Tar-acid—Furfural: | | Wood flour filler |10¹⁰-10¹² |400-600 Mineral filler |10⁹-10¹¹ |200-500 Fabric filler |0.4 × 10¹¹ |200-500 Urea—Formaldehyde |(2-2.8) × 10¹³ |650-720 Vinyl, unfilled |10¹⁴ |400-500 Vinyl, filled |10¹¹ |350-400 Acrylate |10¹⁵ |480 Polystyrene |10¹⁷-10¹⁸ |500-700 Other plastics: | | Shellac compound | |100-400 Cold molded: | | Nonrefractory |1.3 × 10¹² |85