Hydroxyapatite exfoliated graphite reinforced polyolefins for high performance applications

Abstract

The use of polyolefins as a matrix for polymer nanocomposites newlinebecome ubiquitous due to their wide spectrum of properties and newlineapplications. The applications include grocery bags, toys to automotive newlineparts, prosthetic implants etc. Polyethylene and polypropylene are the two newlinemost widely used polyolefins. Several attempts have been made to enhance newlinethe properties of these thermoplastics. With the rapid growth of newlinenanotechnology, the development of nanocomposites offers a promising newlinemeans of modifying the performance of these polymers. Even with the newlineadvent of high performance plastics, the importance of polyolefins has not newlinealleviated due to the tailored properties brought about by addition of newlinenanofillers. The diverse spectrum of nanofillers include metal oxides, silica, newlinenanoclay, carbon nanotubes, graphene etc. newlineHydroxyapatite (HA) with the molecular formula Ca10(PO4)6(OH)2 is newlinethe main mineral component of hard tissue such as bone, dental enamel etc. newlineIt gives the bone rigidity and compressive strength. The first part of the newlinepresent work aims at preparation of rod shaped nanoHA of low particle size newlineby a cost effective method from eggshell. newlineEventhough numerous studies have been reported on the use of HA newlineloaded polyolefins, the reinforcing effect of HA at a low loading has not newlinebeen discussed much. In this study the mechanical and thermal properties of newlinepolyolefin-HA nanocomposites were investigated in detail by preparing the newlinecomposites with LLDPE, HDPE and PP. Also the effect of HA at high newlineloading has been explored in composites of LLDPE by incorporating upto newline40 weight percent of HA. Carbonaceous fillers like graphene, carbon nanotube, carbon fibers, newlineexfoliated graphite etc find unique position in the nanoworld owing to the newlineunusual augmentation in the thermal, electrical, mechanical and chemical newlineproperties. The reinforcing effect of a layered filler like exfoliated graphite newline(EG) on the mechanical, thermal and electrical properties in the microwave newlineregion at low loading in LLDPE, HDPE and PP were investigated.