The Strength and Stretch of Double Texture Rubber Goods

RUBBER articles may be divided roughly into three classes: (1) pure gum, (2) hard rubber, and (3) various combinations of rubber and textile fibers. This latter class is the largest and possibly the most important of the group, and includes besides tires the bulk of mechanical goods, such as hose, belting and sheet goods of various kinds. Probably no combination of useful materials affords a wider range of possibilities than the various combinations of rubber and textile fibers. In rubber-textile combinations the cotton fiber is ordinarily used to impart tensile strength and to decrease the stretchiness of the product, while the attempt is made to retain at the same time as much resiliency as possible. Most of these combinations are of laminated construction, consisting of alternate layers of rubber compound and woven fabric, the physical properties being controlled by the construction of the fabric and the composition and cure of the rubber compound. Since cotton is usually more expensive on a volume basis than rubber, it is desirable to obtain the maximum tensile properties of the cotton fiber and to restrict its use as much as possible. That this is a difficult matter may be recalled when we compare the actual bursting strength of various mechanical goods with the so-called theoretical or calculated strength based on the additive strengths of the plied up fabrics in the fabricated article; it is at once apparent that only a small proportion of the fiber strength is effectively employed.