**4. Conclusions**

The research paradigm on PWTCs has recently been shifted from duplex thermal composites to triplex thermal composites, which however lacks of the design standards. It is therefore stressed that the fabrication of PWTCs should be reported conforming with the screening requisites of specific applications, because proclaim is that every PWTCs is not applicable everywhere. Shape-stability is the design standard, but it may be essential only for a few applications, most importantly including thermal management of buildings and fabrics. Instead of shape-stability, high thermal energy storage capability and high thermal conductivity are the most important parameters for thermal management of heat-emitting devices and systems where mechanical enclosures are essential, helping in controlling the liquid drainage threats. Thus, shape-stabilizers should be carefully employed. In all, attention should be paid on thermal reinforcements such that the optimal PWTCs can be created. Most importantly, the focus should be asserted on the thermal interface between paraffin waxes and thermal reinforcement which is the backbone allowing the development of well-defined thermal paths for higher thermal conductivities of PWTCs. On the whole, three main hypotheses should be carefully checked for an ideal PWTC strictly depending on the target application: (i) preservation of optimal latent heat, (ii) maintenance of the trade-off between thermal conductivity enhancement and latent heat reduction, (iii) achievement of the optimal shape-stability.
