Differential thermal analysis offers a convenient and rapid way of determining stabilization levels in polyolefin compositions. Since it is normally used at temperatures in the fabrication range, it provides a direct readout of processing stability. At the same time, because the chemistry of the polymer system at these temperatures may be quite different from that at normal use temperatures, judgment must be exercised in attempting to extrapolate high temperature data. New factors can come in at either end of the temperature range which are inoperative at the other extreme.The experimental procedures used are described, and the special precautions necessary for operation down to the 140-150°C range indicated. Problems arising from sample inhomogeneities are discussed, and the critical importance of stabilizer migration in the solid state pointed out, including invalidation of extrapolation down to normal temperatures of data taken above the melting range.

Nursing home patients often receive more drugs than needed. Drug incompatibilities frequently are found, and PRN orders are apt to be overused. Regulatory agencies require periodic physician review in the hope of eliminating these loose prescribing habits. A study was made of the drugs prescribed for 98 patients in a proprietary nursing home. The principal findings were that PRN orders can indeed be inappropriate and indiscriminately followed, and that the multiplicity of drugs often prescribed can lead to drug incompatibilities and to additional illness of the patient. Concern is expressed about the medication review process currently in vogue in nursing homes.

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Empirical test data on low‐density polyethylenes exposed to the elements for very long times are compared with results on samples of the same materials subjected to artificial “weathering” in a modified carbon arc machine. The test results conform to the expression where ta is hours of accelerated weathering, tn years of natural exposure, and the constants B and k have values of 150 and 2.4, respectively, for the materials and test conditions involved. Earlier results are confirmed in that optimum weather resistance is found to depend on good dispersion of a fine‐particle black. Protection improves with concentration up to the limit of about 5% by weight imposed by degenerative effects on mechanical properties from higher loadings of the fine channel blacks. Dependence of weatherability on molecular weight (melt index) is noted.

Much has been written on the theoretical mechanisms by which the oxidation of polyolefins is believed to proceed and on the role of stabilizers in impeding this process. Relatively little information is available on the effects of some of the interesting, practical considerations—stress, stabilizer stability and the consequences of crystalline content and texture to name a few—which exert a controlling influence on the behavior of these materials in real‐life situations. Data are presented on the aging behavior of low‐ and high‐density polyethylenes at temperatues in the range 50‐110°C in the presence of copper and on the utility and limitations of oxygen absorption and differential thermal analysis as tools for accelerated prediction of this behavior.