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This thesis summarizes the results concerning the manufacture of medical implants for bone replacement using electron beam melting (EBM) which is an additive manufacturing (AM) technology, and aims to satisfy the engineering needs for the medical functionality of manufacturing technology. This thesis has focused on some microscopic properties for surfaces and bone integration. The process parameters of EBM manufacturing were studied to ascertain whether they have impacts on surface appearance, as surface properties have impacts on bone integration and implant performance. EBM manufacturing uses an electron beam to melt metal powder onto each layer in a manner akin to welding. The electron beam is controlled by process parameters that may be altered to a certain extent by the operator. There are individual process parameters for every material, and new parameters are set when developing new materials. In this thesis, process parameters in default settings were altered to ascertain whether it was possible to specify process parameters for implant manufacturing. The blood chamber model was used for thromboinflammation validation, using human whole blood. The model is used to identify early reactions of coagulation and immunoreactions. The material used in this study was Ti6Al4V-ELI, which is corrosion resistant and has the same surface oxide layers as titanium, and CoCr-F75, which has high stiffness, is wear-resistant and is commonly used in articulating joints. The study shows that among the process parameters researched, a combination of speed and current have the most impact on surface roughness and an interaction of parameters were found using design of experiment (DOE). As-built EBM surfaces show thrombogenicity, which in previous studies has been associated with bone ingrowth. Surface structure of as-build EBM manufactured surfaces are similar to implants surfaces described by Pilliar (2005), but with superior material properties than those of implants with sintered metals beads. By altering the process parameters controlling the electron beam, surface roughness of as-build parts may be affected, and the rougher EBM manufactured surfaces tend to be more thrombogen than the finer EBM manufactured surfaces. As-build EBM manufactured surfaces in general show more thrombogenicity than conventional machined implants surfaces. / Denna avhandling behandlar tillverkning av medicinska implantat för integration i ben. I fokus är den additiva tillverkningstekniken ”elektronstrålesmältning” ( Electron Beam Melting –EBM), en av flera tekniker som populärt beskrivs med termen 3D-skrivare. Avhandlingen fokuserar på mikroskopiska ytegenskaper och dess inverkan på benintegration. Processparametrarna för EBM-tillverkning studerades för att fastställa hur de påverkar ytans utseende, efter som ytegenskaper har effekt på implantatens funktion. EBM-tillverkning använder en elektronstråle som likt svetsning smälter ihop metallpulver. Elektronstrålen styrs av processparametrar som till viss mån kan justeras av maskinoperatören. Det finns individuella processparametrar för varje material och nya parametrar utvecklas till varje ny legering. I denna avhandling har ”grundinställningarnas processparametrar” studerats för att ta reda på om det är möjligt att ställa in specifika parametrar till implantattillverkning. Med hjälp av blodkammarmetoden, som använder humant blod, har thromboinflammatoriska egenskaper undersökts. Metoden identifierar tidiga koagulations- och immunologiska reaktioner. Legeringarna som undersökts i denna studie var Ti6Al4V-ELI, som är korrosionsbeständigt med samma uppsättning oxider på ytan som titan har, och CoCr-F75, en legering som har hög styvhet, är slitstarkt och är vanligt förekommande i implantat för leder. Bland de undersökta processparametrarna visar en kombination av hastighet och ström ha mest inverkan på ytjämnhet och en interaktion mellan parametrar identifierades med hjälp av försöksplanering. EBM-tillverkade ytor visade på thrombogena egenskaper som i tidigare studier kan relateras till god integration i benvävnad. Ytstrukturen hos EBM-tillverkade ytor liknar de implantatytor som Pilliar (2005) beskriver, men materialegenskaperna är bättre än de materialegenskaper som implantat, med sintrad yta, har. Genom att ändra processparametrarna som styr elektronstrålen kan ytstrukturen påverkas. Grövre EBM-tillverkade ytor tenderar att vara mer thrombogena än de finare EBM-tillverkade ytorna är. Obehandlade EBM-tillverkade ytor i allmänhet är mer thrombogena än vad konventionellt framställda implantatytor är.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Naiqian Zhang / Soil surface roughness is a major factor influencing soil erosion by wind and water. Studying surface roughness requires accurate Digital Elevation Model (DEM) data. A vehicle-based laser measurement system was developed to generate high-resolution DEM data. The system consisted of five units: a laser line scanner to measure the surface elevation, a gyroscope sensor to monitor the attitude of the vehicle, a real-time kinematic GPS to provide the geographic positioning, a frame-rail mechanism to support the sensors, and a data-acquisition and control unit. A user interface program was developed to control the laser system and to collect the sensors data through a field laptop. Laboratory experiments were conducted to evaluate the performance of the laser sensor on different type of targets. The results indicated that the laser measurement on a white paper had the least variability than that on other targets. The laser distance measurement was calibrated using the data acquired on the white paper. Static accuracy tests of the gyroscope sensor on a platform that allowed two-axis rotations showed that angle measurement errors observed in combined pitch/roll rotations were larger than those in single rotations. Within ±30° of single rotations, the measurement errors for pitch and roll angles were within 0.8° and 0.4°, respectively. A model to study the effect of attitude measurement error on elevation measurement was also developed. DEM models were created by interpolating the raw laser data using a two-dimensional, three-nearest neighbor, distance-weighted algorithm. The DEM models can be used to identify shapes of different objects. The accuracy of the laser system in elevation measurement was evaluated by comparing the DEM data generated by the laser system for an unknown surface with that generated by a more accurate laser system for the same surface. Within four replications, the highest correlation coefficient between the measured and reference DEMs was 0.9371. The correlation coefficients among the four replications were greater than 0.948. After a median threshold filter and a median filter were applied to the raw laser data before and after the interpolation, respectively, the correlation coefficient between the measured and reference DEMs was improved to 0.954. Correlation coefficients of greater than 0.988 were achieved among the four replications. Grayscale images, which were created from the intensity data provided by the laser scanner, showed the potential to identify crop residues on soil surfaces. Results of an ambient light test indicated that neither sunlight nor fluorescent light affected the elevation measurement of the laser system. A rail vibration test showed that the linear rail slightly titled towards the laser scanner, which caused small variations in the pitch angle. A preliminary test on a bare soil surface was conducted to evaluate the capability of the laser system in measuring the DEM of geo-referenced surfaces. A cross-validation algorithm was developed to remove outliers. The results indicated that the system was capable of providing geo-referenced DEM data.

Published Article / This paper explores the manipulation of Van der Waals' forces by geometrical parameters in a micro-material handling system. It was observed that the flat-flat interactive surfaces exerted the highest intensity of Van der Waals' forces followed by cone-flat, cylinder-flat, sphere-flat and sphere-sphere interactive surfaces, respectively. A conical micro-gripper proved to be versatile in manipulating the Van der Waals' forces efficiently in a 'picking up' and 'releasing' mechanism of micro-work parts. It was deduced that the pick-up position should be rough and spherical, and the placement position should be smooth and flat for an effective 'pick-and-place' cycle to be realised.

Résumé: Le développement de l’industrie des polymères fourni de plus en plus de choix pour la formulation de matériaux pour les couvre-planchers. Les caoutchoucs, le PVC et le linoleum sont les polymères habituellement utilisés dans l’industrie des couvre-planchers. Ce projet répond à un problème de facilité de nettoyage des couvre-planchers de caoutchouc qui sont reconnus pour être mous, collants et ayant une surface rugueuse. L’INTRODUCTION couvrira l’état actuel de la recherche sur les couvre-planchers, surtout en regard au problème de la «nettoyabilité». La théorie pertinente et les informations générales sur les polymères, les composites polymériques et la science des surfaces seront introduites au CHAPITRE 1. Ensuite, le CHAPITRE 2 couvrira la méthode utilisée pour déterminer la nettoyabilité, l’évaluation des résultats ainsi que l’équipement utilise. Le CHAPITRE 3, discutera des premières expériences sur l’effet de la mouillabilité, la rugosité et la dureté sur la facilité de nettoyage des polymères purs. Plusieurs polymères ayant des surfaces plus ou moins hydrophobes seront investigués afin d’observer leur effet sur la nettoyabilité. L’effet de la rugosité sur la nettoyabilité sera investigué en imprimant une rugosité définie lors du moulage des échantillons; l’influence de la dureté sera également étudiée. Ensuite, un modèle de salissage/nettoyage sera établi à partir de nos résultats et observations afin de rationaliser les facteurs, ou « règles », qui détrminent la facilité de nettoyage des surfaces. Finalement, la réticulation au peroxyde sera étudiée comme une méthode de modification des polymères dans le but d’améliorer leur nettoyabilité; un mécanisme découlant des résultats de ces études sera présenté. Le CHAPITRE 4 étendra cette recherche aux mélanges de polymères; ces derniers servent habituellement à optimiser la performance des polymères purs. Dans ce chapitre, les mêmes tests discutés dans le CHAPITRE 3 seront utilisés pour vérifier le modèle de nettoyabilité établi ci-haut. De plus, l’influence de la non-miscibilité des mélanges de polymères sera discutée du point de vue de la thermodynamique (DSC) et de la morphologie (MEB). L’utilisation de la réticulation par peroxyde sera étudié dans les mélanges EPDM/ (E-ran-MAA(Zn)-ran-BuMA) afin d’améliorer la compatibilité de ces polymères. Les effets du dosage en agent de réticulation et du temps de cuisson seront également examinés. Finalement, un compatibilisant pré-réticulé a été développé pour les mélanges ternaires EPDM/ (E-ran-MAA(Zn)-ran-BuMA)/ HSR; son effet sur la nettoyabilité et sur la morphologie du mélange sera exposé. / Abstract: The development of industrial polymers provides more choices to the design of flooring materials. Rubbers, PVC and linoeleum are the most used polymers in the flooring industry. This project stems from the problem of cleanability (ease of cleaning) of the surface of rubber tile flooring which is known as a soft, sticky and rough surface. In the introduction, the current situation of research on the polymer flooring industry, especially the study on the cleaning problem will be introduced. The relevant theory and general information on polymers, polymer composites and surface science will be introduced in CHAPTER 1. In CHAPTER 2 different approaches, protocols and equipment to evaluate cleanability will be presented. The initial experiments and results (CHAPTER 3) will involve various fundamental concepts on surface wettability, roughness and hardness, as these properties can all influence the surface soiling and cleanability. In single-polymer systems, dozens of polymer materials with a hydrophobic or hydrophilic surface were investigated to observe their soiling and cleaning properties. The effect of roughness was also studied by surface printing method which is used to control the surface topography. Likewise, the influence of surface hardness on cleanability was also investigated with different polymer materials. From the above results and observations, a surface soiling/cleaning model is proposed in attempt to simplify the ― rules ‖ which determine the surface cleanability. Finally, peroxide crosslinking was investigated as a matrix modification method to improve the surface cleanability. The second part of the experiments and results (CHAPTER 4) extends to investigations of polymer blends, in attempt to optimize the performance of single-polymer materials. In this chapter, the surface cleaning model and its relevant rules are examined by the wettability, roughness and hardness tests discussed in CHAPTER 3. The influence of immiscibility on cleaning performance will be discussed in polymer blends from the point of view of thermodynamics (DSC) and morphology (SEM). In order to improve the compatibility in polymer blends, peroxide crosslinking was performed in EPDM/ (E-ran-MAA(Zn)-ran-BuMA) blends. The dosage of curing (cross-linking) agent and curing time were investigated to observe the influence of these experimental conditions on cleanability. Finally, a blend compatibilizer was designed to improve the compatibility of the EPDM/ (E-ran-MAA(Zn)-ran-BuMA)/HSR blends.The compatibilizer prepared by partial pre-crosslinking of EPDM (Nordel) and E-ran-MAA(Zn)-ran-BuMA (Surlyn) was incorpo rated in polymer composites and its influence on cleanability was studied and explained on the basis of changes in morphology of the blend polymer matrix.

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published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

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Raspberry-like polystyrene particles were fabricated through the covalent linkage of small epoxy-functionalized polystyrene particles (PS-GMA) with large amino-functionalized polystyrene particles (PS-NH2). These covalent bonds yielded more stable and robust particle clusters than would be anticipated from non-covalent interactions. While the structures of these raspberry-like particles provided them with a dual-scale hierarchical roughness and re-entrant sites, they were further functionalized with a fluorinated random copolymer to provide them a low surface tension. The fluorinated random copolymer used to functionalize these raspberry-like particles was poly(glycidyl methacrylate20%)-co-2(perfluorooctyl)ethyl methacrylate80%)25 or P(GMA20%-co-FOEMA80%)25, where the subscript 25 denotes the total number of the respective GMA and FOEMA units, while the subscript 20% and 80% denote the molar fractions of GMA and FOEMA, respectively. The epoxy groups of the GMA units could react with the amino groups of the raspberry-like particles, thus incorporating the fluorinated polymer onto the surfaces of the raspberry-like particles. In addition, the FOEMA component provided the particles with enhanced amphiphobicity. Subsequently, these fluorinated raspberry-like particles were cast onto glass slides to demonstrate their superamphiphobic properties. These coatings exhibited superhydrophobic behavior when they were tested against water droplets. Additionally, the oil-repellency of these coatings was tested against various liquids, including diiodomethane, cooking oil, and hexadecane. The coatings exhibited superoleophobic behavior against diiodomethane and cooking oil, as well as highly oleophobic behavior against hexadecane. This work demonstrates a simple and efficient route for the fabrication of superamphiphobic surfaces. Additionally, these surfaces are among the first examples of coatings prepared via self-assembly techniques that exhibited high repellency against hexadecane. These materials could have potential in various applications that require protection of a surface against wetting by either water or oils. / Thesis (Master, Chemistry) -- Queen's University, 2013-10-18 12:36:39.039

Baigiamajame magistro darbe tirta popieriaus paviršiaus ir mechaninių savybių kaita spausdinant fleksografiniais dažais ir keičiant dažų sluoksnio storį. Tyrimams buvo pasirinktos šešios kreidinio ir nekreidinio popieriaus rūšys. Buvo tirtos šių mechaninių ir paviršiaus savybių kaita: spalvinės charakteristikos, atsparumas tempimui ir pailgėjimas, atsparumas lankstymui, PPS šiurkštumas, trinties savybės, popieriaus sugertis. Buvo nustatyta, kad fleksografiniai dažai didina popieriaus šiurkštumą, trūkio jėga ir atsparumas lankstymui visada yra didesni išilgine popieriaus kryptimi, atsparumas tempimui nepriklauso nuo dažų sluoksnio storio, o atsparumas lankstymui mažėja. Darbą sudaro 6 dalys: įvadas, literatūros apžvalga, tyrimo metodika, tyrimų rezultatai ir jų aptarimas, išvados ir siūlymai, literatūros sąrašas. Darbo apimtis – 83 psl. teksto be priedų, 82 iliustracijos, 1 lentelė, 28 bibliografinių šaltinių. / In the Master thesis were investigated the change of the surface and mechanical properties during flexo printing with different ink thickness. 6 papers coated and uncoated grades were tested. Following properties were investigated: colour properties, tension strength and elongation, folding strength, PPS roughness and friction properties. It was found that flexographic ink increases paper PPS roughness, tensile strength and folding resistance is higher in the machine direction in all cases, tensile strength does not depend on the ink thickness and folding resistance becomes smaller. Master thesis includes 6 chapters: introduction, publications review, experimental methods, results and discussion, conclusions and recommendations, references. Master thesis consists of 83 p. (without appendixes), 82 fig., 1 table, and 28 references.