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The purpose of this paper is to investigate the frictional behavior of polytetrafluoroethylene (PTFE) composites under oil‐free sliding conditions.

The friction force and power consumption of pressure packing seals, which were, respectively, made of common filled PTFE, 30 wt% CF (carbon fiber) + PTFE and C/C (carbon/carbon) + PTFE, are studied in a reciprocating oil‐free compressor arrangement. Their coefficient of friction is tested on a block‐on‐ring type tribometer.

The results indicate that influence of mean sliding velocity on filled PTFE composites is apparently more predominant than the others. The friction force curvilinear path of 30 wt% CF+PTFE is hardly influenced by changing crankshaft turn angle. For C/C+PTFE, the effect of mean piston velocity on friction force is not evident. The results also indicate that the friction coefficient of C/C+PTFE is lower than that of 30 wt% CF+PTFE if their applied normal force exceeds 9.8 N. Furthermore, their variation curve of friction force is little different and the power consumption of C/C+PTFE is slightly higher than that of 30 wt% CF+PTFE.

Neither the effect of real contact area on friction coefficient measured in a tribometer nor the influence of the temperature on friction force and power tested in a compressor is not taken into consideration here.

Owing to its good mechanical performances and frictional behaviors, C/C+PTFE is an optimum and promising material under conditions with sealing pressure up to 10 MPa and sliding velocity exceeding 4.0 m/s.

A novel material called C/C+PTFE is considered to make packing rings for oil‐free reciprocating compressors and its friction behaviour is tested on a refitted compressor.

The purpose of this study is to examine the current state of online sustainability reporting in the Hong Kong higher education sector from a variety of perspectives.

The multiple case study was the research method for this research. Content analysis of the university website, as well as interview with university management, personnel in the sustainability office, academics and students, were adopted for data collection. An assessment framework for sustainability reporting was developed as an instrument for content analysis, based on G4 guidelines and prior literature.

The authors observe that most Hong Kong public universities have a specific webpage for sustainability reporting on the website, which consists of an amount of sustainability-related information in terms of general aspects, specific aspects and stakeholder participation. Moreover, they notice that Hong Kong public universities attach importance to sustainability and its reporting, and they would like to communicate their sustainability activities to various stakeholders and the community where they operate.

This paper indicates some practical implications for academics, university management, policymakers and sustainability education amongst universities in Hong Kong and beyond.

This paper argues that universities, as a central place to foster talents and future leaders, should operate in a sustainable manner at the first place and then report their sustainability-related activities taking full advantage of the current information and communication technologies, so as to discharge accountability to various stakeholders and meet the expectations of the community where they operate.

This paper uses a multiple case study approach to explore the status of online sustainability reporting at Hong Kong universities, which contributes to limited research in the area, particularly for online sustainability reporting in the higher education institutions, and makes some contributions to the extant literature.