Dissertations / Theses on the topic 'Mechanical Self-healing'

Self-healing composites are composite materials capable of automatic recovery when damaged. They are inspired by biological systems such as the human skin which are naturally able to heal themselves. Over the past two decades, two major self-healing concepts – based respectively on the use of capsules and vascular networks containing healing agents - have been proposed and material property recovery has been enhanced from 60% to nearly 100%. However, this improvement is still not sufficient to allow self-healing composites to be applied in practice because the healing capability varies with many external factors such as ambient temperatures and damage conditions. The key to the practical application of self-healing composites is to promote the sustainability of healing capacity to make the recovery robust. The thesis presents various techniques to enhance the healing capacity of fibre-reinforced composites to realise strong recovery regardless of ambient temperatures or material types. It presents the effects of various popular configurations of vascular networks on the flexural properties and healing performances of fibre-reinforced composites. The thesis demonstrates a design enabling recovery at ultra-low temperatures by using hollow vascular networks and porous heating elements. It also presents a new healing mechanism to repair the broken structural carbon fibres by incorporating conventional healing agents with short carbon fibres which could be aligned in an in situ electric field. The mechanism was also adopted to enable the restoration of the conductivity of a fibre-reinforced composite incorporating a porous conductive element, a carbon nanotube sheet, which could be used as a heating actuator or a sensing component. Thus, the development reported in this thesis have contributed to promoting the sustainability of the recovery of self-healing composites.

Des hydrogels résistants avec des points de réticulation permanents et temporaires ont été élaborés, et leur structure, leurs propriétés mécaniques et les mécanismes de renforcement ont été étudiés. L’origine de cet important renforcement mécanique vient de l’introduction de points de réticulation temporaires : la rupture de ces liaisons temporaires dissipe de l’énergie de déformation et redistribue les forces locales, qui protègent ainsi les liaisons permanentes qui à leur tour empêchent l’écoulement plastique du réseau. La rhéologie linéaire, les propriétés de traction non-linéaires et les propriétés de fracture de deux doubles réseaux ont été étudiées : un gel de poly(alcool vinylique) réticulé chimiquement par du glutaraldéhyde et réticulé physiquement par des ions borates (gel PVA-borax), et un gel de poly(acrylamide-co-1-vinylimidazole) réticulé chimiquement par du N,N’-Methylenebisacrylamide et réticulé physiquement par des ions métalliques (gel AAm-VIm-M2+). Ces deux doubles réseaux ont des temps de relaxation très différents, ce qui a permis l’étude de la dynamique sur une grande plage de temps. Pour des taux de déformation optimaux, les deux gels présentent un important renforcement mécanique en termes de raideur, de déformation à la rupture et de capacité à résister à la propagation de fissure. Cependant, l’extensibilité et la résistance à la fracture du gel AAm-VIm-M2+ augmentent avec le taux de déformation et avec [M2+] tandis que la tendance inverse est observée pour le système Borax, ce qui suggère que, au-delà du temps de relaxation principal en petites déformations, les détails de l’architecture du réseau chimique et physique à l’équilibre sont importants pour le processus de fracture
Tough hydrogels with permanent and transient crosslinks have been designed, and their structure, mechanical properties, and their reinforcement mechanisms have been investigated. The origin of this strong mechanical reinforcement comes from the introduction of the transient crosslinks, the breaking of these transient bonds dissipate strain energy and redistribute local forces, preventing the irreversible rupture of the permanent bonds, while the permanent bonds prevent the network from plastic flow. The linear rheology, nonlinear tensile and fracture properties of two different dual crosslink gels have been studied: a poly(vinyl alcohol) gel chemically crosslinked by glutaraldehyde and physically crosslinked with borate ion (PVA-borax gel), and a poly(acrylamide-co-1-vinylimidazole) gel chemically crosslinked by N,N'-Methylenebisacrylamide and physically crosslinked by metal ions (AAm-VIm-M2+ gel). These two dual crosslink gels have very different relaxation times, which made it possible to investigate the dynamics over a large time range. For optimized strain rates, both gel systems exhibited strong mechanical reinforcement in terms of stiffness, strain at failure, and the ability to resist crack propagation. However the extensibility and fracture toughness of the AAm-VIm-M2+ gel increased with strain rate and [M2+] while the opposite trend was observed for the Borax system, suggesting that, beyond the main relaxation time, the details of the chemical and equilibrium physical network architecture are important for the fracture process

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 127-136).
The functional versatility and endurable self-healing capacity of soft materials in nature is found to originate from the dynamic supramolecular scaffolds assembled via reversible interactions. To mimic this strategy, extensive efforts have been made to design polymer networks with transient crosslinks, which lays the foundation for synthetic self-healing hydrogels. Towards the development of stronger and faster self-healing hydrogels, understanding and controlling the gel network dynamics is of critical importance, since it provides design principles for key properties such as dynamic mechanics and self-healing performance. For this purpose, a universal strategy independent of exact crosslinking chemistry would be regulating the polymer material's dynamic behavior by optimal network design, yet current understanding of the relationship between network structure and macroscopic dynamic mechanics is still limited, and implementation of complex network structure has always been challenging. In this thesis, we show how the dynamic mechanical properties in a hydrogel can be controlled by rational design of polymer network structures. Using mussel-inspired reversible catechol coordination chemistry, we developed a nanocomposite hydrogel network (NP gel) with hierarchical assembly of polymer chains on iron oxide (Fe3O4) nanoparticles as network crosslinks. With NP gel as a model system, we first investigated its unique dynamic mechanics in comparison with traditional permanent and dynamic gels, and discovered a general approach to manipulate the network dynamics by controlling the crosslink structural functionality. Then we further explored the underlying relationship between polymer network structure and two key parameters in relaxation mechanics, which elucidated universal approaches for designing relaxation patterns in supramolecular transient gel network. Finally, by utilizing these design principles, we designed a hybrid gel network using two crosslinking structures with distinct relaxation timescales. By simply adjusting the ratio of two crosslinks, we can precisely tune the material's dynamic mechanics from a viscoelastic fluid to a rigid solid. Such controllability in dynamic mechanics enabled performance optimization towards mechanically rigid and fast self-healing hydrogel materials.
by Qiaochu Li.
Ph. D.

Ce travail traite de l’auto-cicatrisation bactérienne de béton C35/45 de classe de consistance de S4 et une classe d'environnement d’exposition XF3.Un adjuvant bactérien a été incorporé à la formulation avec une concentration de 105 cellules/ml. Il est constitué de Bacillus Subtilis de peptone et d’extrait de levure. On montre que l’incorporation de l’adjuvant bactérien entraîne une diminution de la porosité et de la perméabilité aux gaz, une augmentation des résistances mécaniques, du module dynamique et une amélioration de la durabilité. Une auto-cicatrisation complète des échantillons micro fissurés a été observée à 44 jours. La validité de l'utilisation du modèle EuroCode 2, pour prédire l’acquisition des résistances au cours du temps, a été vérifiée et validée. Cependant on observe, qu’après 90 jours de cure, l’effet de l’adjuvant bactérien sur les propriétés étudiées s’estompe, phénomène dû au passage des bactéries d’un état actif à un état inactif et par conséquent d’une forme végétative à un état sporulé. Ainsi, l’utilisation de ce type d’adjuvant bactérien ne permettra pas la réparation des structures qui s’endommagent après quelques années de leur mise en service. La méthode, dite « indirecte », semble la mieux appropriée dans ces cas de figure. La bactérie est, alors, immobilisée avec des nutriments dans d'autres matériaux poreux. On propose d’utiliser les granulats légers de type argile expansée. Une étude préliminaire, conduite dans ce travail, consiste à trouver le % de granulats légers à incorporer dans la formulation du béton sans en affecter les propriétés d’usage. Pour ce faire une étude a été réalisée sur le mortier du béton équivalent. Six mortiers ont été élaborés en faisant varier le taux de substitution du sable naturel par le sable leger, Tv (0, 10%, 25%, 50%, 75%, 100%). Elle a conduit à l’établissement de relations entre les propriétés du mortier et sa résistance à la compression ainsi que sa masse volumique, cette dernière propriété étant reliée au taux d’incorporation, Tv, ainsi que la masse volumique du sable.On démontre que Tv=10% est la fraction volumique optimale de granulats légers. Un béton incorporant 10% de granulat léger a été élaboré et ses caractéristiques comparées au béton de contrôle. On montre que le béton incorporant 10% de granulat léger peut être utilisé comme un béton de structure
This work deals with bacterial self-healing of concrete of C35 / 45 resistance class, S4 consistency class and an XF3 exposure environment class.A bacterial adjuvant was included in the formulation with a concentration of 105 cells / ml. It consists of Bacillus Subtilis peptone and yeast extract. It is shown that the incorporation of the bacterial adjuvant results in a decrease in porosity and gas permeability, an increase in mechanical strength, dynamic modulus and an improvement in durability. Complete self-healing of micro fissured specimens was observed at 44 days. The validity of the use of the EuroCode 2 model, to predict the acquisition of resistances over the time, was verified and validated. However, it is observed that after 90 days, the effect of the bacterial adjuvant on the studied properties reaches a steady state, due to the passage of bacteria from an active state to an inactive state and therefore of a form vegetative to a sporulated state. Thus, the use of this type of bacterial adjuvant will not allow the repair of damaged structures after a few years of their service life. The so-called "indirect" method seems the most appropriate in these cases. The bacterium is, then, immobilized with nutrients in other porous materials. It is proposed to use expanded clay type aggregates.A preliminary study has been conducted in order to find the percentage of lightweight aggregates to incorporate in the concrete formulation without affecting the properties of use. Hence, six mortars were elaborated by incorporating different volumetric rates of lightweight sand (0%, 10%, 25%, 50%, 75% and 100%). Relationships between the mechanical and thermal characteristics and the compressive strength as well the density of mortars were established. The density was related to the rate of incorporation, Tv, as well as the density of the sand.It is exhibited that Tv = 10% is the optimum volume fraction of lightweight sand. A concrete incorporating 10% of lightweight aggregate has been formulated and its characteristics compared to control concrete. It is shown that concrete incorporating 10% light aggregate can be used as structural concrete

There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary. One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result of lithium diffusion during charging and discharging operations. When lithium is inserted in either the positive or negative electrode, there is a volume change associated with insertion or de-insertion. Diffusion-induced stresses (DISs) can therefore cause the nucleation and growth of cracks, leading to mechanical degradation of the batteries. With different mathematical models we studied the behavior of diffusion induces stresses and effects of electrode shape, size, concentration dependent material properties, pre-existing cracks, phase transformations, operating conditions etc. on the diffusion induced stresses. Thus we develop tools to guide the design of the electrode material with better mechanical stability for durable batteries. Along with mechanical degradation, chemical degradation of batteries also plays an important role in deciding battery cycle life. The instability of commonly employed electrolytes results in solid electrolyte interphase (SEI) formation. Although SEI formation contributes to irreversible capacity loss, the SEI layer is necessary, as it passivates the electrode-electrolyte interface from further solvent decomposition. SEI layer and diffusion induced stresses are inter-dependent and affect each-other. We study coupled chemical-mechanical degradation of electrode materials to understand the capacity fading of the battery with cycling. With the understanding of chemical and mechanical degradation, we develop a simple phenomenological model to predict battery life. On the experimental part we come up with a novel concept of using liquid metal alloy as a self-healing battery electrode. We develop a method to prepare thin film liquid gallium electrode on a conductive substrate. This enabled us to perform a series of electrochemical and characterization experiments which certify that liquid electrode undergo liquid-solid-liquid transition and thus self-heals the cracks formed during de-insertion. Thus the mechanical degradation can be avoided. We also perform ab-initio calculations to understand the equilibrium potential of various lithium-gallium phases.

Abstract : The objective of this work is the characterization of heat and mechanical damage in the mortar by the nonlinear acoustic waves. The correlation between non-linear/linear acoustic parameters and damage in mortar is studied based on experiments and modelling. Experimental measurements of non-linear acoustic parameters as a function of temperature and crack size were performed on mortar. The velocities showed a decrease when increasing the degradation and the non-linear parameters showed an increase when increasing the damage. For the heat damage, cylindrical specimens were prepared and were characterized by studying the porosity and saturation. Then, the temperature controls the degradation. Indeed, the linear acoustic (UPV) and non-linear acoustic (Higher harmonic generation) were applied to characterize the damage. The linear acoustic tests have shown that the longitudinal, transverse velocities and modulus of Young of the mortar decreases in function of the temperature. The non-linear acoustic tests have shown that beta increases in function of the temperature. For the mechanical damage and the self-healing, an annular specimens were prepared and cracked by controlling the size of each crack. Then the self-healing phenomenon was characterized by the permeability and the acoustic tests. Indeed, the permeability tests have shown that the airflow and the crack size decreases quickly in the first month then slowly for the rest of the self-healing process. On the other hand, the non-linear acoustic tests shown that the alpha and beta decreases according to the self-healing process which means that the nonlinear parameters are good indicators to characterize the self-healing. Moreover, the analysis of the experimental results indicates that the frequency resonant technique is more efficient to characterize the defects in the mortar than the higher harmonic generation. From the experimental tests and to get a general result independent for our case study, the nonlinear parameters were related to a damage index. A polynomial correlations of a 2nd degree was established between the nonlinear parameters and the index damage. A numerical model based on the finite element volume was proposed to establish a correlation between the crack size and the airflow. The numerical results were compared with the results of the permeability tests and shown a good agreement. The findings of this work should be most appropriate as a foundation for the study of the self-healing by the nonlinear acoustic waves.
Résumé : L'objectif de ce travail est la caractérisation de l’endommagement thermique et mécanique dans le mortier par les ondes acoustiques non linéaires. La corrélation entre les paramètres acoustiques linéaires et non linéaires est basée sur les essais expérimentaux et la modélisation. Des mesures expérimentales des paramètres acoustiques non linéaires en fonction de la taille de la fissure et la température ont été effectuées sur mortier. Les vitesses ont montré une diminution et les paramètres non linéaires ont montré une augmentation en augmentant le degré de fissuration. Pour l’endommagement thermique, des éprouvettes cylindriques ont été préparées et ont été caractérisées par l'étude de la porosité et de la saturation. L'acoustique linéaire (UPV) et l’acoustique non linéaire (génération d'harmoniques) ont été appliquées afin de quantifier l’endommagement. Les essais acoustiques linéaires ont montré que les vitesses transversales, longitudinales et le module d'Young du mortier diminuent en fonction de la température. Les essais acoustiques non linéaires ont montré l'augmentation du bêta est fonction de l’endommagement thermique. Pour l’endommagement mécanique et l'autocicatrisation, des anneaux de mortier ont été préparés et fissurés en contrôlant la taille de chaque fissure. Ensuite, le phénomène d'autocicatrisation est suivi par la perméabilité et des essais acoustiques. Les essais de perméabilité ont montré que le débit d'air et la taille de la fissure diminuent rapidement au cours du premier mois, puis lentement durant le reste du processus d'autocicatrisation. D'autre part, les tests acoustiques non linéaires ont montré que « alpha » et « bêta » diminuent durant le processus de l’autocicatrisation, ce qui signifie que les paramètres non linéaires sont des bons indicateurs pour caractériser ce phénomène. En outre, l'analyse des résultats expérimentaux indique que la technique de résonance de fréquence est plus efficace pour caractériser les défauts dans le mortier que la génération d'harmoniques plus élevés. À partir des essais expérimentaux et dans le but d'obtenir un résultat plus général indépendant de notre cas d’étude, les paramètres non linéaires ont été liés à un index d’endommagement. Une corrélation polynomiale de 2e degré a été établie entre les paramètres non linéaires et l’index d’endommagement. Un modèle numérique basé sur la méthode des volumes finis a été proposé afin d'établir une corrélation entre la taille de la fissure et le flux d'air. Les résultats numériques ont été comparés avec les résultats des tests de perméabilité et montré un bon accord. Les résultats de ce travail représentent un bon départ pour étudier le phénomène de l'autocicatrisation par les ondes acoustiques non linéaires.

L'objectif de ce travail est la caractérisation de l’endommagement thermique et mécanique dans le mortier par les ondes acoustiques non linéaires. La corrélation entre les paramètres acoustiques linéaires et non-linéaires étudiée est basée sur les essais expérimentaux et la modélisation. Pour l’endommagement thermique, des éprouvettes cylindriques ont été préparées et caractérisées par l'étude de la porosité et la saturation. Ensuite, l'acoustique linéaire et l’acoustique non linéaire (génération d'harmoniques) ont été appliquées afin de quantifier l’endommagement. Les essais acoustiques linéaires ont prouvé que les vitesses transversales, longitudinales et le module d'Young du mortier diminue en fonction de la température. Les essais acoustiques non linéaires ont montré l'augmentation du bêta fonction de la température. Pour l’endommagement mécanique, le phénomène d'autocicatrisation est suivi par la perméabilité et les essais acoustiques. Les essais de perméabilité ont montré que le débit d'air et la taille de la fissure diminue rapidement au cours du premier mois, puis lentement durant le reste du processus d'autocicatrisation. D'autre part, les tests acoustiques non linéaires ont montré que « alpha » et « bêta » diminuent durant le processus de l’autocicatrisation qui signifie que les paramètres non linéaires sont un bon indicateur pour caractériser ce phénomène. A partir des résultats expérimentaux, une corrélation polynomiale de 2ème degré a été établie entre les paramètres non linéaires et l’index d’endommagement. Les résultats de ce travail représentent un bon départ pour étudier le phénomène de l'autocicatrisation par les ondes acoustiques non linéaires
The objective of this work is the characterization of heat and mechanical damage in the mortar by the nonlinear acoustic waves. The correlation between non-linear/linear acoustic parameters and damage in mortar is studied based on experiments and modelling. For the heat damage, cylindrical specimens were prepared and were characterized by studying the porosity and saturation. Indeed, the linear acoustic (UPV) and non-linear acoustic (Higher harmonic generation) were applied to characterize the damage. The linear acoustic tests have shown that velocities and modulus of Young of the mortar decreases in function of the temperature. The non-linear acoustic tests have shown that beta increases in function of the temperature.For the mechanical damage. The self-healing phenomenon was characterized by the permeability and the acoustic tests. Indeed, the permeability tests have shown that the airflow and the crack size decreases quickly in the first month then slowly for the rest of the self-healing process. On the other hand, the non-linear acoustic tests shown that the alpha and beta decreases according to the self healing process which means that the nonlinear parameters are a good indicators to characterize the self-healing. Moreover, the analysis of the experimental results indicates that the frequency resonant technique is more efficient to characterize the defects in the mortar than the higher harmonic generation. A polynomial correlations of a 2nd degree was established between the nonlinear parameters and the index damage. The findings of this work should be most appropriate as a foundation for the study of the self healing by the nonlinear acoustic waves

Les performances exceptionnelles des composites naturels comme la nacre ou le bois émergent de l’arrangement précis d’éléments souples et rigides à l’échelle nanométrique. L’assemblage couche-par-couche permet la fabrication de films avec un contrôle nanométrique de l’organisation et de la composition. Ce travail décrit l’assemblage et les propriétés de nouveaux nano-composites contenant des nano-renforts 1-D (fibrilles de cellulose) et 2-D (plaquettes d’argile). Nous avons combiné les argiles avec une matrice extrêmement souple de poly(diméthylsiloxane) dans une architecture lamellaire imitant celle de la nacre. Nous avons étudié des composites à base de fibrilles de cellulose aléatoirement orientées dans le plan, puis alignées dans une direction pour mieux imiter les parois cellulaires du bois. Les propriétés mécaniques de ces composites bio-inspirés égalent ou surpassent celles de leurs homologues naturels, tout en étant transparents et dans certains cas auto-réparants
Natural materials such as nacre or wood gain their exceptional mechanical performances from the precise organisation of rigid and soft components at the nano-scale. Layer-by-layer assembly allows the preparation of films with a nano-scale control over their organisation and composition. This work describes the assembly and properties of new nano-composites containing 1-D (cellulose nano-fibrils) and 2-D (clay nano-platelets) reinforcing elements. The clay platelets were combined with an extremely soft matrix (poly(dimethylsiloxane)) to mimic the lamellar architecture of nacre. Cellulose based composites with a random in plane orientation of the fibrils were studied first, later we aligned the fibrils in a single direction to mimic further the cell wall of wood. The mechanical properties of these bio-inspired composites match or surpass those of their natural counterparts, while being transparent and in one case self-repairing

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.
Source: Dissertation Abstracts International, Volume: 68-06, Section: B, page: 4099. Adviser: Nancy R. Sottos. Includes bibliographical references (leaves 118-121) Available on microfilm from Pro Quest Information and Learning.

Yes
Engineered Cementitious Composites (ECC) is a material which possesses advanced self-healing properties. Although the self-healing performance of ECC has been revealed in numerous studies, only small-scale, laboratory-size specimens have been used to assess it under fixed laboratory conditions and curing techniques. In order to evaluate the effect of intrinsic self-healing ability of ECC on the properties of structural-size, large-scale reinforced-beam members, specimens with four different shear span to effective depth (a/d) ratios, ranging from 1 to 4, were prepared to evaluate the effects of shear and flexural deformation. To ensure a realistic assessment, beams were cured using wet burlap, similar to on-site curing. Each beam was tested for mechanical properties including load-carrying capacity, deflection capacity, ductility ratio, yield stiffness, energy absorption capacity, and the influence of self-healing, by comparing types of failure and cracking. Self-healed test beams showed higher strength, energy absorption capacity and ductility ratio than damaged test beams. In test beams with an a/d ratio of 4 in which flexural behavior was prominent, self-healing application was highly successful; the strength, energy absorption capacity and ductility ratios of these beams achieved the level of undamaged beams. In addition, flexural cracks healed better, helping recover the properties of beams with predominantly flexural cracks rather than shear cracks.
The authors gratefully acknowledge the financial assistance of the Scientific and Technical Research Council (TUBITAK) of Turkey provided under Project: MAG-112M876 and the Turkish Academy of Sciences, Young Scientist Award program. The second author would also like to acknowledge the financial support of TÜBITAK for the 2219 Scholarship.

碩士
國立成功大學
化學工程學系
105
The polyampholyte (PA) hydrogels were successfully synthesized by thermal-polymerization method. Polyampholytes are composed of randomly dispersed cationic and anionic repeating groups. The physical cross-linking of ionic side-chains gives the hydrogels self-healing and strong mechanical properties. In this study, N,N’-methylenebis(acrylamide) (Bis-Am) is served as chemical cross-linker to enhance the mechanical property of hydrogels. 2-hydroxyethyl methacrylate (HEMA) containing hydroxyl group is incorporated to improve water content. Introducing of non-ionic units changes supramolecular construction and significantly affects the properties of the fabricated gels. The results showed the hydrogels cross-linked with Bis-Am exhibiting strong mechanical property but losing water content simultaneously. The results suggest that chemical cross-linker hold the polymer network more tightly and made the hydrogel rigid but offered less space for water storage. In contrast to Bis-Am, HEMA indeed helped to absorb more water but caused the hydrogels weak due to incapability of joining ion-pair cross-linking system. By introducing such agents, the Young’s modulus was promoted from 0.4 to 2.4 MPa and the water content was boosted from 62% to 73%. With proper molar ratio of ionic groups, the PA hydrogels showed great self-healing performance. Adding of excess non-ionic agents interrupted the re-forming of ionic side chains led to fail in self-healing. In this study, a simple approach to adjust the properties of PA hydrogels was developed.

Indiana University-Purdue University Indianapolis (IUPUI)
This work is focused on developing viable self-healing coatings, especially considering the viability of the coating in a commercial context. With this in mind, finding low cost healing agents, with satisfactory healing and mechanical properties as well as adapting the healing system for use in coatings was required. Seven potential healing agents were evaluated and an air-drying triglyceride (linseed oil) was identified as the candidate healing agent. Different encapsulation techniques were evaluated and ureaformaldehyde microcapsules were chosen as the candidate encapsulation technique. Self-healing coatings were fabricated using urea-formaldehyde encapsulated linseed oil. EIS, SEM and TGA technologies were used to evaluate mechanical performance, corrosion resistance, and self-healing performance.

Extending the functional lifetime of acrylic poly(methyl methacrylate) (PMMA) bone cement may reduce the number of revision total joint replacement (TJR) surgeries performed each year. We developed a system utilizing an encapsulated water-reactive, FDA-approved tissue adhesive, 2-octyl cyanoacrylate (OCA), as a healing agent to repair microcracks within a bone cement matrix. The proposed research tested the following hypotheses: (1) reactive OCA can be successfully encapsulated and the resulting capsules thoroughly characterized; (2) the static mechanical properties of the PMMA composite can be improved or maintained through inclusion of an optimal wt% of OCA-containing capsules; (3) PMMA containing encapsulated OCA has a prolonged lifetime when compared with a capsule-free PMMA control as measured by the number of cycles to failure; and (4) the addition of capsules to the PMMA does not significantly alter the biocompatibility of the material. Based on the experiments reported herein, the primary conclusions of this dissertation are as follows: (1) functional OCA can be encapsulated within polyurethane spheres and successfully incorporated into PMMA bone cement; (2) lower wt% of capsules maintained the tensile, compressive, fracture toughness, and bending properties of the PMMA; (3) inclusion of 5 wt% of OCA-containing capsules in the matrix increased the number of cycles to failure when compared to unfilled specimens and those filled with OCA-free capsules; and (4) MG63 human osteosarcoma cell proliferation and viability were unchanged following exposure to OCA-containing PMMA when compared with a capsule-free control.

Dissertation