Hot Compaction
Layers of film are compacted under heat and pressure so that selected melting occurs resulting in a useable sheet with enhanced modulus and strength. In the case of oriented polyethylene film, each drawn film contain a variety of crystals or lamella with different lamellar thicknesses.Thus if the temperature is properly controlled so that only the thinner crystal melt, these melted crystals become the glue holding the thicker crystals together, i.e a type of self-reinforcement. (RDC 6/6/2011) [Hine, Unwin and Ward, Polymer, 52,#13, 2891-2898 (2011)]
Recent Journal Articles
The use of an interleaved film for optimising the properties of hot compacted polyethylene single polymer composites
(2891-2898) Polymer 52 #13 (2011)
Hine, Unwin, and Ward of the University of Leeds, and the University of Bradford, United Kingdom, showed that the incorporation of interleaved films has major advantages for the production of polyethylene single polymer composites by the process of selective melting (termed hot compaction). The key issue is to choose a compaction temperature which melts the minimum amount of the original oriented elements whilst achieving acceptable bonding within the compacted structure. Utilising an interleaved film, excellent interlayer peel strengths can be achieved at lower compaction temperatures giving greater retention of the oriented fraction of the original fibres or tapes and a wider processing window. For example, using a very high modulus, ultra-high molecular weight, polyethylene tape, together with an interleaved film, resulted in an in-plane modulus of 25 GPa, an in-plane strength of 500 MPa, and an interlayer strength of >10 N/10 mm. These are amongst the highest values reported for a single polymer composite. (RDC 6/2/2011)