Mechanical processing of cotton causes two types of damage: the first type is physical in nature, resulting from the breaking and bruising of fibers; the second type is chemical in nature, as shown by a decrease in D.P. This change in D.P. is brought about by a mechanical-chemical rupture of molecular bonds and not through a thermal mechanism. A quantitative estimate of the relative damage occurring in each mechanical operation investigated is presented. A loss in D.P of 30 percent was measured as a result of the mechanical operations which converted an Empire seed cotton into yarn.

The use of central measures o! lifetime to characterize fatigue behavior is misleading, and more attention should be p?ld to early failures and expected minimum life. Diflerences in the dispersions of lifetimes between samples may lead to faulty conclusions if these are based on mean lifetimes. The possible dependence of dispersion on stroke is considered. Because of dispersion in fatigue data, it is necessary to test large numbers of specimens to make reliable predictions.The inadequacy of observed central values as bases for judging the applicability of a distribution is discussed. Criticism leveled against the commonly used logarithmicnormal distribution is cited. Criteria are presented for the development of a lifetime distribution that takes into account the physical realities of the fatigue process.Analytical expressions for a number of concepts in the statistics of fatigue are reviewed. The theory suggesting the application of the third asymptotic distribution is outlined. The distribution has been adapted to accumulated fatigue data on an acrylic fiber sample.

A new technique for analyzing data which appears to improve the use of the traces obtained by differential scanning calorimetry is based on a procedure for obtaining the true heat capacity base line for a system undergoing a thermal event, allowing enthalpy change to be isolated from heat capacity contributions. Experimental data on cotton and poly(methyl methacrylate) illustrate the resulting improvement in determination of enthalpy changes, peak temperatures, and kinetic data.