xm.A, 6 King: Philippine Coir and Coir Cordage 315 



The moduli of tensile elasticity, E, were computed from the 

 data given in columns 9, 10, and 11, Tables VI, VII, and VIII. 

 The notations used are: 



S = Stress in kilograms per square centimeter or in pounds per square 

 inch. 



L=: Gauged length of the filament (100 millimeters). 



1= Elongation in millimeters. 



E = Modulus of tensile elasticity in either kilograms per square centi- 

 meter or pounds per square inch. 



TP S „ SX L 



^ = r/L °^ ^ = 1- 



The typical tests as recorded in Table VIII show that abaca 

 filaments are almost perfectly elastic up to the point of rupture, 

 at a stress often as high as 8,000 kilograms per square centi- 

 meter, as shown by the modulus of elasticity. 



Fig. 2 shows the stress-deformation graphs of an abaca 150- 

 millimeter filament section, grade "F" fiber, taken at random and 

 of a single filament No. 4 of machine-cleaned coir, which has 

 the greatest elasticity of any coir specimen tested. If a fila- 

 ment has no elasticity, the stress-deformation graph will be a 

 curved line from the beginning of tension to the point of rup- 

 ture ; on the other hand, if a filament has perfect elasticity, the 

 graph will be represented by a straight line. It will be noted 

 that the linear relationship between stress and deformation in 

 the abaca filament section is practically ideal, as shown by the 

 straight line in the graph, which persists to the point of rupture ; 

 while the data on the coir specimen give a stress-deformation 

 graph having a very short, initial, straight-line portion. This 

 indicates that there was perfect elasticity where the stress and 

 deformation for a short period at the outset were directly pro- 

 portional as shown on the graph between and 308 kilograms 

 per square centimeter. In other words, the straight portion of 

 this graph shows that the filament would spring back to its 

 original shape and length if it were unloaded at the point cor- 

 responding to the stress of 308 kilograms per square centimeter 

 and the elongation of 2 millimeters. When stressed beyond 308 

 kilograms per square centimeter the filament begins to elongate 

 rapidly, but the corresponding stress does not increase at the 

 same rate; and, if the load is removed, the filament will no 

 longer return to its original length, because it has become per- 

 manently set. Filament No. 4 is typical of only very coarse 

 filaments already classified as brush or bristle fiber rather than 

 as cordage fiber. 



