SYNOPSISThe structure of the surface cross-linking layer of high-density polyethylene (HDPE) produced by plasma treatment was studied by DSC, X-ray diffraction, elemental analysis, and infrared analysis. The relationship between the cross-linking and the durability of the modification efficiency provided by the plasma treatment was investigated. The results of the structure analysis indicated that the polar groups introduced by the plasma just locate on the upper surface of the cross-linking layer and the chemical constitution and structure of the inner part of the cross-linking layer is similar to that of the uncross-linking HDPE. The cross-linking density of the gel decreases from the surface to the inside with a large gradient and the average cross-linking degree of the whole gel is rather low. Nevertheless, the experiment proved that this cross-linking layer can limit the mobility of the molecules in the cross-linking layer and hinder the decay of the treatment efficiency significantly. When the surface cross-linking induced by plasma reaches a certain extent, the treatment efficiency will remain relatively constant in storage. 0

SYNOPSISGas chromatography/mass spectrometry studies of gas condensates in plasma and pyrolysis products of plasma polymer for benzaldehyde were made. Both products' analyses indicate the significant presence of benzyl and carbonyl groups in plasma polymer samples. Infrared measurements were also used to correlate the structures suggested by GC/MS results. A radical mechanism, which involved hydrogen abstraction, aldehyde group abstraction, and benzyl fragmentation under plasma activation, was proposed. The highly crosslinked and branched structures of the plasma polymer were attributed to the subsequent reactivity of free radicals, formed as a result of the scission of the chemical bonds in the benzaldehyde molecules.

The sex attractant pheromone of the tea tussock moth, a serious economic pest of tea plantations in southern China, has been identified as 10,14‐dimethylpentadecyl isobutyrate. A synthesis of the racemic form of the pheromone was developed, and traps baited with the synthetic compound at doses of 40–1000 micrograms captured male moths. The synthetic pheromone was as effective as a trap bait as, virgin female moths, or extracts of female moths.

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