Understanding straining induced changes in thermal properties of tropocollagen-hydroxyapatite interfacial configurations

Abstract

Abstract:The ability of a biomaterial to transport energy by conduction is best characterised in the steady state by its thermal conductivity and in the non-steady state by its thermal diffusivity. The complex hierarchical structure of most biomaterials makes the direct determination of the thermal diffusivity and thermal conductivity difficult using experimental methods. This study presents a classical molecular simulation-based approach for the thermal diffusivity and thermal conductivity prediction for a set of tropocollagen and hydroxyapatite-based idealised biomaterial interfaces. The thermal diffusivity and thermal conductivity are calculated using the presented approach at five levels of straining (10% compressive, 5% compressive, 0%, 5% tensile, 10% tensile) at 300 K. The effects of straining, interfacial period and thickness of simulated systems on the thermal properties are analysed. Analyses point out important role played by interfaces and straining in determining biomaterial thermal properties including establishment of a notion that straining can be used to tailor the thermal properties (thermal diffusivity and thermal conductivity) of the organic-inorganic interfacial system and nanocomposite systems.Keywords: tropocollagen; hydroxyapatite; thermal diffusivity; thermal conductivity; straining; interfacial configuration; molecular dynamics.Reference to this paper should be made as follows: Qu, T. and Tomar, V. (2015) 'Understanding straining induced changes in thermal properties of tropocollagen-hydroxyapatite interfacial configurations', Int.

A computational study of mechanical properties of collagen-based bio-composites

“…The collagen/CNT bio-composites have a much higher heat capacity than the mineralized bio-composites and a lower total bio-composite mass. Overall, collagen/CNT bio-composites have stress vs. strain behaviors, elastic moduli, and gap/overlap ratios comparable to those of mineralized bio-composites, but with a higher heat capacity that would allow collagen/CNT bio-composites to be less susceptible to thermal damage during implantation or functional use in applications like bone machining, as pointed out by Qu and Tomar (Qu and Tomar 2015). This includes uses such as high-speed drilling (Wiggins and Malkin 1976), laser ablation (Nelson et al 1988), or the curing of cements in implants (Huiskes 1980).…”

“…We compare the specific heat capacity for each of our models to the specific heat capacity values determined by Qu and Tomar (Qu and Tomar 2015 ) in Table 3 . We find that the heat capacities for our models were an order of magnitude larger than those determined by Qu and Tomar.…”

“…A non-mineralized collagenous bio-composite with 4–10 wt% SWCNT has a 19% difference in heat capacity from a 40 wt% mineralized bio-composite, while a collagenous bio-composite with 11 wt% MWCNT has a 196% difference from a 40 wt% mineralized bio-composite. The heat capacity of CNTs and HAP are both in the range of 700 to 1000 Jkg −1 K −1 (Pradhan et al 2009 ; Qu and Tomar 2015 ). However, the collagen/MWCNT model has a significantly larger specific heat capacity.…”

“…Heat Capacity C P (Jkg −1 K −1 ) 0 wt% mineral reinforcement 49040 ± 4194 20 wt% mineral reinforcement 68728 ± 20154 40 wt% mineral reinforcement 79727 ± 13213 (4-10) wt% SWCNT reinforcement 96643 ± 65642 11 wt% MWCNT reinforcement 7112337 ± 73723 Collagen-HAP composite (Qu and Tomar 2015) ≈20000 bio-composite, while a collagenous bio-composite with 11 wt% MWCNT has a 196% difference from a 40 wt% mineralized bio-composite. The heat capacity of CNTs and HAP are both in the range of 700 to 1000 Jkg −1 K −1 (Pradhan et al 2009;Qu and Tomar 2015). However, the collagen/MWCNT model has a significantly larger specific heat capacity.…”

“…Experiments by Holmes et al find that telopeptide cross-link cleavage alters the flow of heat and structure of collagen (Holmes et al 2017 ). Qu and Tomar used molecular dynamics simulations to study the thermal properties of collagen-hydroxyapatite nanocomposites and found that the weight fractions, material geometry, and strain all affect the bio-composite’s thermal properties (Qu and Tomar 2015 ).…”