Shape stabilised phase change materials based on a high melt viscosity HDPE and paraffin waxes

Shape stabilised phase change materials (SSPCMs) based on a high density poly(ethylene)(hv-HDPE) with high (H-PW, Tm = 56–58 °C) and low (L-PW, Tm = 18–23 °C) melting point paraffin waxes were readily prepared using twin-screw extrusion. The thermo-physical properties of these materials were assessed using a combination of techniques and their suitability for latent heat thermal energy storage (LHTES) assessed. The melt processing temperature (160 °C) of the HDPE used was well below the onset of thermal decomposition of H-PW (220 °C), but above that for L-PW (130 °C), although the decomposition process extended over a range of 120 °C and the residence time of L-PW in the extruder was <30 s. The SSPCMs prepared had latent heats up to 89 J/g and the enthalpy values for H-PW in the respective blends decreased with increasing H-PW loading, as a consequence of co-crystallisation of H-PW and hv-HDPE. Static and dynamic mechanical analysis confirmed both waxes have a plasticisation effect on this HDPE. Irrespective of the mode of deformation (tension, flexural, compression) modulus and stress decreased with increased wax loading in the blend, but the H-PW blends were mechanically superior to those with L-PW.

Ghosts and Television

This chapter explores the ghost story on television, and particularly the tensions between the medium and the genre. Television has long been seen as a nearly-supernatural medium, an association that the very term 'medium' enhances. In particular, the very intimacy of television, and its domestic presence, have led to it being considered to be a suitable and effective venue for the ghost story, while at the same time concerns have risen over it being too effective at conveying horror into the home. The ghost story is thus one of the genres where the tensions between the medium's aesthetic possibilities and desire for censorship can be most clearly seen. As such, there is a recurring use of the ghost story in relation to different techniques of special effects and narrative on television, some more effective than others, and the presence of the ghost story on television waxes and wanes as different styles become more or less popular, and different narrative forms, such as single play or serial or series, become more or less dominant. Drawing on examples primarily from a British and US context, this chapter outlines the history of the ghost story on television and demonstrates how the tensions in presentation, narrative and considerations of the viewer have influenced the many changes that have taken place within the genre.