An assessment of web-based textbook supplementary material to support student learning

There is an increasing trend by publishers to provide supplementary learning materials with text books in order to improve the learning experience and thus ultimately improve text book sales. This study will aim to establish the use of these materials and their relevance to students in terms of supporting student learning. The materials include multiple choice test banks, animated demonstrations, simulations, quizzes and electronic versions of the text. The study will focus on the extensive library of web-based learning materials available on the ‘WileyPlus’ web platform which accompanies the textbook ‘Operations Management’, 2nd edition authored by A. Greasley and published by John Wiley and Sons Ltd.

Phenols and aromatic amines as thermal stabilizers in polyolefin processing

Scavenging of C- and O-centered free radicals is mandatory in processing stabilization of polypropylene. Phenolic antioxidants act principally as O-radical scavengers only. Aromatic amines, N,N'-disubstituted 1,4-phenylenediamines (PD) and 4,4'disubstituted diphenylamines (DPA), scavenge both C- and O-centered radicals and have consequently a broader activity spectrum. PD cannot be used, however, in polypropylene because of formation of strongly discoloring and staining sacrificial transformation products. Such products formed from DPA have even more discoloring properties. A good processing stability and acceptable extent of discoloration can be achieved by blends of phenols with 4,4'-di-tert.octyl DPA. The effect is considered as a beneficial cooperation between the two chain-breaking antioxidants involving interactions with amine-based transformation products.