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Polyimides function under high‐temperature sliding. The available literature explains transitions in friction and wear mainly by mechanical effects, such as influences of normal load, sliding velocity and humidity on polymer transfer to steel counterfaces. Theoretical models are evaluated for sintered and thermoplastic polyimides. Tribologists have been interested in tribochemical and tribophysical reactions in the sliding interface for about 25 years. Reactions such as hydrolysis, imidisation and/or degradation occur as a function of sliding temperature and are reviewed in this paper. An overview of polyimide synthesis and degradation is presented, while new insights in sliding mechanisms are obtained from a detailed study of Raman spectroscopy on worn polymer surfaces.magnified image

Abstract.  This paper deals with an elliptical construction in Hungarian that to our knowledge has not received any attention in the theoretical literature so far. It involves the deletion of a relative clause with the exclusion of the relative pronoun and one more remaining constituent. We show that this construction should be analyzed as an instance of sluicing. The theoretical approach we provide for these sentences is an adapted version of Merchant's (2001) implementation of sluicing in terms of an [e]‐feature that is responsible for the deletion process. Our extension of this proposal involves the modification of the syntactic subcontent of this [e]‐feature. We show that languages where question words are found in the operator domain of the left periphery use a version of the [e]‐feature that attaches to heads whose specifier is occupied by an operator. This predicts that sluicing not only occurs with wh‐remnants but more widely with operator remnants as well. With this proposal we lay the foundation for a crosslinguistic taxonomy of sluicing constructions, and open new avenues towards explaining root/embedded asymmetries in some as yet ill‐understood elliptical phenomena in English.

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The main goal of this article is to show that four properties of roots can be derived in a principled manner from the theory of Merge. The properties in question are the following: (a) roots have no grammatical features, (b) roots have no syntactic category, (c) roots are defined structurally rather than lexically, and (d) roots are dominated by functional material (rather than the other way around). We argue that the first Merge operation in each cyclic domain creates a radically empty structural position at the foot of the structure in which a root can be inserted at the level of Vocabulary Insertion. The four abovementioned properties of roots can then be shown to follow straightforwardly from this theory.