THE INDIA RUBBER WORLD 



629 



TENTATIVE SPECIFICATIONS FOE ADHESIVE INSULATING TAPE. 



Serial Pesicnation: D— 19 T.. IssLed, 1919. 

 1. These specifications cover a friction tape composed of cotton sheetin 

 impregnated with an adhesive insulating compound. 



the fabric 

 of the tape are separated. 



II. PHYSICAL PROPERTIES AND IFSTS. 



7. When the tape is held before a strong licht, the number of pin 

 Tioles noted per linear yard of tape, J^-inch wide, shall not exceed two. 



8. The tensile --.trength per_ ^-inch width shall be not less than 3C 

 n the jaws of the testing machin 



separati' 



distan 



iiche 



of the 



s per 

 Wher 



degree C. for 16 hours. 



10. (a) The adhesioi 

 plies shall he such that 



:lean, smooth copper rod and baked at 100 



ampound shall not discolor the cooper. 



the friction coat of compound between ■ the 

 a strip of tape 2 feet long and Ji-inch wide 



-ind upon a 1-inch mandrel under tension of 

 TA pounds at the rate of 30 inches per minute, a weight of 3 pounds shall 

 ■not cause the plies to separate at a greater rate than 30 inches per minute. 



(b) After a strip has been exposed to dry heat at 100 degrees C. for 

 18 hours and then cooled to room temperature, a test specimen shall with- 

 stand the test prescribed in the Paragraph (a), except that the weight 

 applied to unwind the tape shall be 1 pound instead of 3 pounds. 



11. The test f..r dielectric strength shall be made as follows: the tape 

 shall be spir.dly wound v;ith one-third lap on a smooth metal rod, 1 inch 

 in diameter, fnr a distance of 6 inches. Two inches in the center shall be 

 covered with tin foil and bound down securely with tape, and an alternat- 

 ing potential cf 1 OCO volts, of a frequency of not over 65 cycles, shall 

 he applied for five minutes between the metal rod and the tin foil without 



12. One '/;-pound roll for each 250 roll 

 for the various tests. .At least two feet of I 

 removed and one specimen taken for each test, 

 one test, two additional specimens shall be tak 



ihall be selected at random 



the outer layers shall be 



f the tape fails 



fails 



■ial shall be rejected 



pound 



additional 



III. STAND.<RD WEIGHT. DIMENSIO.\S AND VARIATIONS. 



The net weight of the tape, fi-inch wide, shall be not less than 

 ces per roll, exclusive of core, wrapping, and box. 

 The length of J<-inch tape shall be not less than 55 yards per 



The width shall not vary from that specified 



IV. PACKING AND MARKING. 



16. Each roll shall be wrapped in oiled paper 

 closed in a suitable box. The wrapping shall be secure 

 oughly protect the contents. 



17. Each boK shall be marked with the name of the n 

 trade mark, and the nomitial width and weight of the tape. 



V. INSPECTION. 



IS. The tape shall be tested and inspected within four 

 of delivery. 



than 



:0.03 



l-'rom practical laboratory experiments it has long been 

 known that the rate of gain in tensile strength due to 

 moisttire absorption in various textiles bears a very direct rela- 

 tion to the weight of the fabric. While very heavy fabrics and 

 those woven closely are slow in reaching their full regain, the 

 increase in strength is very great. On the other hand, light 

 fabrics of a gauze-like nature obtain their regains quickly and 

 show but little increase in strength from this source. It is there- 

 fore manifestly incorrect to assume a standard rate of increase 

 for all weights of textiles. In order to investigate this subject 

 the chairman tested a variety of fabrics, ranging from a very 

 open cheese-cloth weighing about 1^ ounce per square yard up 

 to the heaviest obtainable duck, having a weight of about 50 

 ounces per square yard. 



The fabrics were tested in groups of eight or ten specimens 

 each at various regains, passing from a bone-dry condition at 

 one end of the scale to that at which all the moisture possible 

 had been absorbed from an atmosphere having a relative 

 humidity of 80 per cent. The moisture content was deter- 

 mined in each case by weighing on analytical balances before 

 and after drying in an electric oven at a temperature of. 220 

 degrees F. . . ■ . 



The results are plotted in Figure 1, and show to the same 

 scale the wide range in strength increase with the various 

 weights of fabric. In all cases strip specimens were used meas- 

 ured to 1"X inches wide and ravelled accurately to 1 inch. 

 The distance between jaws was 3 inches in all cases and the 

 speed of the moving jaw 12 inches per minulc. Wh'lc weigh- 



Moisture Re3a)n,percentof DiyWeisht. 

 i-ic. I. \abiation in Tensile Strength in Textiles Due to Moisture. 

 ing, the moist specimens were in all cases enclosed in air-tight 

 containers, so that the moisture could not vary. The follow- 

 ing is the detail of the tests : 



Fabric A.— An ope 

 32 filling threads per 

 or, at a regain of 6 per cent, 1.54 ounces. 



Moisture, percent 5.37 10.49 



Average tensile strength, pounds 17.0 19.8 21.8 



Fabric B. — JO-inch "ounce Osnaburg. A very good standard fabric of 

 this class 40 warp by 3C filling threads per inch. The bone-dry weight 

 was 7.64 ounces per si), yard and, at 6 per cent regain, 8,10 ounces. 



Moistuic, per cent 4.76 6.87 10.88 



.\vtragc tensile strength, pounds... 43.6 57.8 67.4 71.9 



Fabric C. — Mercerized cotton airplane wing fabric. Normal weight 4 

 ounces per stiuare yard; 3/80* yarn, with 68 threads per inch of width in 



arp 



oi Moistu 



1'abric D.- 

 his cloth wi 

 ;gain. 5.48 . 



tilling, 

 r this fillir.g !s taken from a paper, "The Effect . 

 ngth of Aircraft Fabrics," presented by the chair 

 feting of the Society.^ 



Cotton bag sheeting 48 by 48, 2.85-yard goods 36 i 

 ghed Lone dry 5.17 ounces per square yard and, at 

 Hices per square yard. 



per cent , .. 0- 4.76 6.87 10.88 



lensile strength, jiounds. . . 54.3 69.3 73.0 83.3 



-30-inch 7-dunce 'Osnaburg. ' Exceptionally clean. The bone- 

 s 8.12 ounces per s<(uare yard and, at 6 per cent regain, 8.60 



nches wide. 



Moisture, per ceiTI .'........' '. . " 



Average tensile-, strensth, pounds.,. - 

 ■adhic F.— Standard ll/23« by 11/23' 

 carded Egyptian cotton, 17 'A ounces 



4.76 6.87 10.88 



!6.1 75.1 85.3 93.1 

 square woven tire fabric, ii 

 per square yard, under noi 



mal 



ilot for this fabric was originally derived by Messrs. Yeaton and 

 re in the Textile Laboratory at the Massachusetts Institute of 

 ogy. The plat was also presented by the author of the paper to 

 eference has just been made. 



c G. — A moderately heavy duck used in the manufacture of stitched 

 jelts. The warp threads are 6 ply 26 per inch and the filling 5 ply 



regain. 29.1 



weighed 27.5 oz. per sq. yd and, at 6 



Various Moisture 



Maximum 



Regain, 



Fabric. Per Cent. 



^—Cheese-cloth 10.40 



<— Osnaburg 10.88 



"—Wing fabric 10.33 



1— Sheeting , lO.f 



te of Increase 



n Per Cent 



Dry Strength 



Jry 



r Each Per 

 Cent of Moistui 



Weight 

 at 6 Per 



10.88 

 ).00 



■6-.67 

 9.53 

 17.12 



Kepc 



Materials. 



