skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Towards an Understanding of the Role of Aragonite in the Mechanical Properties of Nacre

Abstract

Nacre, also known as mother-of-pearl, is a biocomposite material that exhibits higher strength and fracture toughness than its component materials. It derives its strength from the brick-and-mortar layering of aragonite (CaCO{sub 3}) platelets and organic binder. It is believed that the protein binder helps redistribute the stress throughout all tablets for optimal mechanical performance. In this study, we attempt to measure the mechanical properties of aragonite within nacre and compare them to bulk aragonite and bulk nacre and understand the redistribution of stresses. Here we show that x-ray diffraction techniques are useful for isolating and measuring strain of crystallites within a composite material. Our results show that the apparent stiffness of aragonite varies with crystallographic directions and is higher than the stiffness of bulk nacre in all cases, meaning that aragonite tablets are exposed to less than the average bulk stress. The average force applied to the bulk sample is partitioned between the aragonite and the binder, so that the protein layer bears as much as 27.2% of the total applied force. Different crystallographic directions exhibit behaviors different than bulk aragonite or bulk nacre. These are related to texture of aragonite platelets (i.e. preferred orientations within nacre). By examining nacre,more » we can obtain a better understanding of the mechanical relationship between the ceramic and polymer in composite materials. We expect that x-ray diffraction will become the standard method for probing the mechanical properties of composite materials.« less

Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
992942
Report Number(s):
SLAC-TN-10-005
TRN: US201023%%392
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ARAGONITE; BINDERS; CERAMICS; COMPOSITE MATERIALS; FLEXIBILITY; FRACTURE PROPERTIES; GRAIN ORIENTATION; MECHANICAL PROPERTIES; PERFORMANCE; POLYMERS; PROTEINS; STRAINS; STRESSES; TEXTURE; X-RAY DIFFRACTION

Citation Formats

. Towards an Understanding of the Role of Aragonite in the Mechanical Properties of Nacre. United States: N. p., 2010. Web. doi:10.2172/992942.
. Towards an Understanding of the Role of Aragonite in the Mechanical Properties of Nacre. United States. https://doi.org/10.2172/992942
. 2010. "Towards an Understanding of the Role of Aragonite in the Mechanical Properties of Nacre". United States. https://doi.org/10.2172/992942. https://www.osti.gov/servlets/purl/992942.
@article{osti_992942,
title = {Towards an Understanding of the Role of Aragonite in the Mechanical Properties of Nacre},
author = {},
abstractNote = {Nacre, also known as mother-of-pearl, is a biocomposite material that exhibits higher strength and fracture toughness than its component materials. It derives its strength from the brick-and-mortar layering of aragonite (CaCO{sub 3}) platelets and organic binder. It is believed that the protein binder helps redistribute the stress throughout all tablets for optimal mechanical performance. In this study, we attempt to measure the mechanical properties of aragonite within nacre and compare them to bulk aragonite and bulk nacre and understand the redistribution of stresses. Here we show that x-ray diffraction techniques are useful for isolating and measuring strain of crystallites within a composite material. Our results show that the apparent stiffness of aragonite varies with crystallographic directions and is higher than the stiffness of bulk nacre in all cases, meaning that aragonite tablets are exposed to less than the average bulk stress. The average force applied to the bulk sample is partitioned between the aragonite and the binder, so that the protein layer bears as much as 27.2% of the total applied force. Different crystallographic directions exhibit behaviors different than bulk aragonite or bulk nacre. These are related to texture of aragonite platelets (i.e. preferred orientations within nacre). By examining nacre, we can obtain a better understanding of the mechanical relationship between the ceramic and polymer in composite materials. We expect that x-ray diffraction will become the standard method for probing the mechanical properties of composite materials.},
doi = {10.2172/992942},
url = {https://www.osti.gov/biblio/992942}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Aug 25 00:00:00 EDT 2010},
month = {Wed Aug 25 00:00:00 EDT 2010}
}