Nanoscale Damping Characteristics of Boron Nitride Nanotubes and Carbon Nanotubes Reinforced Polymer Composites

Abstract

This study compares the damping behavior of boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs) as reinforcement in PLC, a biodegradable copolymer. The damping behavior of PLC composites reinforced with 2 wt % or 5 wt % nanotube filler is evaluated by nanodynamic mechanical analysis (NanoDMA). The addition of 2 wt % CNT leads to the greatest enhancement in damping (tan δ) behavior. This is attributed to pullout in CNTs because of lower interfacial shear strength with the polymer matrix and a more effective sword-in-sheath mechanism as opposed to BNNTs which have bamboo-like nodes. BNNTs however have a superior distribution in the PLC polymer matrix enabling higher contents of BNNT to further enhance the damping behavior. This is in contrast with CNTs which agglomerate at higher concentrations, thus preventing further improvement at higher concentrations. It is observed that for different compositions, tan δ values show no significant changes over varying dynamic loads or prolonged cycles. This shows the ability of nanotube mechanisms to function at varying strain rates and to survive long cycles.

Ions-modified nanoparticles affect functional remineralization and energy dissipation through the resin-dentin interface

“…Nano-DMA revealed that there is heterogeneity in the mechanical property distribution of both intertubular and peritubular dentin in the group of 24 h of storage. The nano-DMA analysis of the complex modulus at peritubular dentin in samples treated with Ca-NPs stored for 24 h permitted observation of zones with higher E* (215.78 GPa) close to areas of lower modulus (116.84 GPa at intertubular dentin, 110.04 GPa at the bottom of the hybrid layer, or 64.34 GPa at the hybrid layer) (Table 2), which might hinder the dissipation of energy through the interface (Agrawal et al, 2013). Low modulus regions lead to stress concentration in relatively high elastic modulus regions (Misra et al, 2004).…”

“…This growing made that viscoelasticity values at both intertubular and peritubular dentin became homogeneous facilitating, thereby, the dissipation of energy throughout their structures (Agrawal et al, 2013). Even more, the range of discrepant values among the four constituents of the adhesive interface when Ca-or Zn-doped NPs were employed diminished after 21 d of storage, contributing to lower resistance to deformation within the interface after prolonged storage.…”

Nanoscopic dynamic mechanical analysis of resin–infiltrated dentine, under in vitro chewing and bruxism events

“…The different viscoelastic properties which show both type of dentines could be a result of the high concentration of collagen fibrils in the intertubular dentine, and is an outcome of higher store potential energy available for elastic recoil (Balooch et al, 2004) at peritubular dentine (Table 3). At tubular structures, energy dissipation can occur via deformation in axial and radial directions (Agrawal et al, 2013), as validated from the FESEM images. One of the major damage mechanisms during cycling loading in a tubular system is the formation of microcracks that propagate along the tubular process, becoming unstable after exceeding a critical threshold.…”

“…Dissipation of energy within the structures is of prime importance in dynamic systems (Agrawal et al, 2013) such as the oral function, where teeth and restorations require damping to absorb shock waves and alleviate stresses. Hence, improving damping characteristics becomes imperative for enhancing their robustness thereby expanding their lifetimes.…”

Zinc-Containing Restorations Create Amorphous Biogenic Apatite at the Carious Dentin Interface: A X-Ray Diffraction (XRD) Crystal Lattice Analysis

“…8). It has been stated that tubular system suppress failure through crack-bridging and frictional pullout (Agrawal et al, 2013), nucleating minerals at micro and nano-scale damaged zones. Those mineral formations maintained anchored directly or indirectly (crack-bridging) the intratubular deposits of minerals to the peritubular dentin (Figs.…”