Document Abstract
ANTEC Papers: 2002
The Development of Nanocomposites to Enhance Functionality of Materials for Rotational Molding
Darren Martin, Peter Halley, Rowan Truss, Michael Murphy and Simon Meusburger The University of Queensland Oliver Jackson, The Queensland Manufacturing Institute Brisbane, Australia
The development of new composite materials with enhanced property profiles for rotational molding represents a key challenge for the industry. The prerequisite attributes of a good rotomolding resin include grindability, sinterability, thermal stability and low moisture sensitivity. This imposes very restrictive limits on the number of promising new candidates. When traditional glass fibres or other mineral fillers such as talc, mica, or calcium carbonate are used, increased stiffness is almost always achieved at the expense of impact properties, ease of processing, wear on equipment, low density and recyclability. Many mineral fillers have been used successfully in numerous high pressure plastic forming processes, however, their successful adaptation has not transposed to the low shear, low pressure environment found in rotational moulding. In addition, large fibres tend to create a natural sieving action when tumbled with plastic powder within the mold and end up lining the inside of the mold serving no useful mechanical purpose. Furthermore, surface finish is generally rougher than that achieved with just the base resin and so it is harder to achieve a glossy finish. Possibly a more successful approach to developing a rotomoldable composite with outstanding engineering properties would be to introduce the matrix and reinforcement into the mold as a curable liquid. This has been done with some degree of success using wollastonite-filled polyurethane (1), although at higher filler loadings impact properties also suffered. In this paper polymer-clay nanocomposites are presented as possible new candidates for rotational molding. Issues and choices relating to the formulation, trials and evaluation of both PE-clay (thermoplastic) and castable polyurethane-clay (thermoset) nanocomposites for rotational molding are discussed. Some key melt rheology results for the PE-based nanocomposites are reported.