Centrifuging Effect on the Structure and Property of Natural Rubber Latex Films.

The structure and property of the films produced from natural rubber latexes such as field latex (FL) and single, double, and triple centrifuged latexes were studied by x-ray diffraction and mechanical testing methods, respectively. Mechanical test shows that tensile strength of the film increases after single centrifugation and then decreases with higher order centrifugation, whereas elongation-at-break (EB) decreases with successive centrifugation. X-ray diffraction study clearly reveals a change of average molecular packing and structural element of the centrifuged films. These results clarify that purification of rubber latex by single centrifugation promotes tensile strength resulting from the elimination of inhibitor type of nonrubbery constituents. Higher order centrifugation causes a decrease of this property because of the elimination of accelerator type nonrubbery elements having the sizes of 1.4–2.5 nm and 18–42 nm. The decrease of EB with sequential centrifugation is associated with the removal of both accelerator and inhibitor type particles. [ABSTRACT FROM AUTHOR]