title: How Sensitive Is the Elasticity of Hydroxyapatite-Nanoparticle-Reinforced Chitosan Composite to Changes in Particle Concentration and Crystallization Temperature?
abstract: Hydroxyapatite (HA) nanoparticle-reinforced chitosan composites are biocompatible and biodegradable structural materials that are used as biomaterials in tissue engineering. However, in order for these materials to function effectively as intended, e.g., to provide adequate structural support for repairing damaged tissues, it is necessary to analyse and optimise the material processing parameters that affect the relevant mechanical properties. Here we are concerned with the strength, stiffness and toughness of wet-spun HA-reinforced chitosan fibres. Unlike previous studies which have addressed each of these parameters as singly applied treatments, we have carried out an experiment designed using a two-factor analysis of variance to study the main effects of two key material processing parameters, namely HA concentration and crystallization temperature, and their interactions on the respective mechanical properties of the composite fibres. The analysis reveals that significant interaction occurs between the crystallization temperature and HA concentration. Starting at a low HA concentration level, the magnitude of the respective mechanical properties decreases significantly with increasing HA concentration until a critical HA concentration is reached, at around 0.20-0.30 (HA mass fraction), beyond which the magnitude of the mechanical properties increases significantly with HA concentration. The sensitivity of the mechanical properties to crystallization temperature is masked by the interaction between the two parameters-further analysis reveals that the dependence on crystallization temperature is significant in at least some levels of HA concentration. The magnitude of the mechanical properties of the chitosan composite fibre corresponding to 40 °C is higher than that at 100 °C at low HA concentration; the reverse applies at high HA concentration. In conclusion, the elasticity of the HA nanoparticle-reinforced chitosan composite fibre is sensitive to HA concentration and crystallization temperature, and there exists a critical concentration level whereby the magnitude of the mechanical property is a minimum.
authors.affiliation: Department of Chemical Engineering, The Petroleum Institute, Abu Dhabi, P.O. Box 2533, United Arab Emirates. kwang@pi.ac.ae.
authors.forename: Kean
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Aerospace Engineering, Khalifa University of Science Technology and Research, Abu Dhabi, P.O. Box 127788, United Arab Emirates. kin.liao@kustar.ac.ae.|Department of Mechanical Engineering, Khalifa University of Science Technology and Research, Abu Dhabi, P.O. Box 127788, United Arab Emirates. kin.liao@kustar.ac.ae.
authors.forename: Kin
authors.initials: K
authors.lastname: Liao
authors.affiliation: School of Mechanical & Systems Engineering, Newcastle University, Newcastle Upton Tyne, Tyne and Wear NE1 7RU, UK. kheng-lim.goh@ncl.ac.uk.|NU International Singapore, 172A Ang Mo Kio Avenue 8, #05-01, SIT Building@Nanyang Polytechnic, Singapore 567739, Singapore. kheng-lim.goh@ncl.ac.uk.
authors.forename: Kheng Lim
authors.initials: KL
authors.lastname: Goh
keywords: particle agglomeration; particle shape; stiffness; strength; toughness