Building the map of innovation for membrane materials (Ceramic membranes)

This work proposes a method of visualizing the trend of research in the field of ceramic membranes from 1999 to 2006. The presented approach involves identifying problems encountered during research in the field of ceramic membranes. Patents from US patent database and articles from Science Direct(& by ELSEVIER was analyzed for this work. The identification of problems was achieved with software Knowledgist which focuses on the semantic nature of a sentence to generate series of subject action object structures. The identified problems are classified into major research issues. This classification was used for the visualization of the intensity of research. The image produced gives the relation between the number of patents, with time and the major research issues. The identification of the most cited papers which strongly influence the research of the previously identified major issues in the given field was also carried out. The relations between these papers are presented using the metaphor of social network. The final result of this work are two figures, a diagram showing the change in the studied problems a specified period of time and a figure showing the relations between the major papers and groups of the problems

Non-resorbable glass fibre-reinforced composite with porous surface as bone substitute material: Experimental studies in vitro and in vivo focused on bone-implant interface

The development of load-bearing osseous implant with desired mechanical and surface properties in order to promote incorporation with bone and to eliminate risk of bone resorption and implant failure is a very challenging task. Bone formation and resoption processes depend on the mechanical environment. Certain stress/strain conditions are required to promote new bone growth and to prevent bone mass loss. Conventional metallic implants with high stiffness carry most of the load and the surrounding bone becomes virtually unloaded and inactive. Fibre-reinforced composites offer an interesting alternative to metallic implants, because their mechanical properties can be tailored to be equal to those of bone, by the careful selection of matrix polymer, type of fibres, fibre volume fraction, orientation and length. Successful load transfer at bone-implant interface requires proper fixation between the bone and implant. One promising method to promote fixation is to prepare implants with porous surface. Bone ingrowth into porous surface structure stabilises the system and improves clinical success of the implant. The experimental part of this work was focused on polymethyl methacrylate (PMMA) -based composites with dense load-bearing core and porous surface. Three-dimensionally randomly orientated chopped glass fibres were used to reinforce the composite. A method to fabricate those composites was developed by a solvent treatment technique and some characterisations concerning the functionality of the surface structure were made in vitro and in vivo. Scanning electron microscope observations revealed that the pore size and interconnective porous architecture of the surface layer of the fibre-reinforced composite (FRC) could be optimal for bone ingrowth. Microhardness measurements showed that the solvent treatment did not have an effect on the mechanical properties of the load-bearing core. A push-out test, using dental stone as a bone model material, revealed that short glass fibre-reinforced porous surface layer is strong enough to carry load. Unreacted monomers can cause the chemical necrosis of the tissue, but the levels of leachable resisidual monomers were considerably lower than those found in chemically cured fibre-reinforced dentures and in modified acrylic bone cements. Animal experiments proved that surface porous FRC implant can enhance fixation between bone and FRC. New bone ingrowth into the pores was detected and strong interlocking between bone and the implant was achieved.

A Thermodynamically Consistent Damage Model for Advanced Composites

A continuum damage model for the prediction of damage onset and structural collapse of structures manufactured in fiber-reinforced plastic laminates is proposed. The principal damage mechanisms occurring in the longitudinal and transverse directions of a ply are represented by a damage tensor that is fixed in space. Crack closure under load reversal effects are taken into account using damage variables established as a function of the sign of the components of the stress tensor. Damage activation functions based on the LaRC04 failure criteria are used to predict the different damage mechanisms occurring at the ply level. The constitutive damage model is implemented in a finite element code. The objectivity of the numerical model is assured by regularizing the dissipated energy at a material point using Bazant’s Crack Band Model. To verify the accuracy of the approach, analyses ofcoupon specimens were performed, and the numerical predictions were compared with experimental data

Simulation of Delamination Propagation in Composites Under High-Cycle Fatigue by Means of Cohesive-Zone Models

A damage model for the simulation of delamination propagation under high-cycle fatigue loading is proposed. The basis for the formulation is a cohesive law that links fracture and damage mechanics to establish the evolution of the damage variable in terms of the crack growth rate dA/dN. The damage state is obtained as a function of the loading conditions as well as the experimentally-determined coefficients of the Paris Law crack propagation rates for the material. It is shown that by using the constitutive fatigue damage model in a structural analysis, experimental results can be reproduced without the need of additional model-specific curve-fitting parameters

Micro- and nanostructuring of poly(ethylene-2,6-naphthalate) surfaces, for biomedical applications, using polymer replication techniques

Here we investigate the formation of superficial micro- and nanostructures in poly(ethylene-2,6-naphthalate) (PEN), with a view to their use in biomedical device applications, and compare its performance with a polymer commonly used for the fabrication of these devices, poly(methyl methacrylate) (PMMA). The PEN is found to replicate both micro- and nanostructures in its surface, albeit requiring more forceful replication conditions than PMMA, producing a slight increase in surface hydrophilicity. This ability to form micro/nanostructures, allied to biocompatibility and good optical transparency, suggests that PEN could be a useful material for production of, or for incorporation into, transparent devices for biomedical applications. Such devices will be able to be autoclaved, due to the polymer's high temperature stability, and will be useful for applications where forceful experimental conditions are required, due to a superior chemical resistance over PMMA.

In situ synthesis of nanoclay filled polyethylene using polymer supported metallocene catalyst system

In situ ethylene polymerizations were performed using bis(cyclopentadiene)titanium dichloride supported on polyethersulfone as catalyst. The bis(cyclopentadiene)titanium dichloride supported on polyethersulfone catalyst activity estimated by ethylene polymerization was 360 kgPE/molTi/h. During polymerization the fillers used were montmorillionite nanoclays having surface modifications with 35-45 wt% dimethyl dialkyl(14-18)amine (FA) and 25-30 wt% trimethyl stearyl ammonium (FB). These fillers were pretreated with methylaluminoxine (MAO; cocatalyst) for better dispersion onto the polymer matrix. The formation of polyethylene within the whole matrix was confirmed by FTIR studies. It was found that the nature of nanofiller did not have any remarkable effect on the melting characteristics of the polymer. TGA study indicates that nanoclay FB filled polyethylene has higher thermal stability than nanoclay FA filled polyethylene. The melting temperature of the obtained polyethylenes was 142 ºC, which corresponds to that synthesized by the polyether sulfone supported catalyst.

Optimization of wood flour acetylation by factorial design and partial least squares regression

Acetylation was performed to reduce the polarity of wood and increase its compatibility with polymer matrices for the production of composites. These reactions were performed first as a function of acetic acid and anhydride concentration in a mixture catalyzed by sulfuric acid. A concentration of 50%/50% (v/v) of acetic acid and anhydride was found to produced the highest conversion rate between the functional groups. After these reactions, the kinetics were investigated by varying times and temperatures using a 3² factorial design, and showed time was the most relevant parameter in determining the conversion of hydroxyl into carbonyl groups.

Síntese de poliuretanos modificados por óleo de mamona empregados em materiais energéticos

The aim of this work was to synthesize a polyurethane polymer matrix using castor oil as a polymer chain modifier, whose characteristics can be adjusted for use as a binder in the manufacture of energetic materials such as propellant and pyrotechnics for aerospace use. We attempted the partial substitution of hydroxyl-terminated polybutadiene (HTPB), a pre-polymer commonly used as a starting polyol in obtaining energetic matrix composites. Thermoanalytical techniques were employed to characterize the material based on castor oil and the unmodified HTPB. The results showed similar behaviors, confirming the possibility of their use as polymer matrix composites through the proposed adaptations.

Desenvolvimento de tecnologia de pré-polímeros na síntese de poliuretanos empregados em combustíveis sólidos

The aim of this work was to synthesize a polyurethane polymer matrix using polyols as a raw material to obtain a binder such as the hydroxyl terminated polybutadiene (HTPB) pre-polymer in energetic material formulation. The soybean-based polyol was the best starting raw material for producing a binder for solid fuel formulation in rocket motor applications. Characterization of the obtained soybean-based polyurethane binder was carried out by employing FT-IR analysis and thermo analytical techniques that showed similar HTPB binder thermo decomposition behaviors, confirming their potential for use as polymer matrix composites.

Pinnoiteteollisuudessa syntyvien maalijätteiden hyötykäyttö ja uudet liiketoimintamahdollisuudet

Tämän diplomityön tavoite on kartoittaa maalien ja lakkojen valmistuksessa syntyvien sivuvirtojen hyötykäyttöä ja hyötykäyttöpotentiaalia nykyisellään. Työn tarkoitus on toimia esiselvityksenä pinnoiteteollisuuden sivuvirtojen hyötykäyttöön liittyvien liiketoimintamahdollisuuksien syvemmälle analyysille. Teollisuuden sivuvirtoihin liittyvää tietoa kerätään tilastoista ja olemassa olevista raporteista sekä haastattelemalla teollisuus- ja palveluyritysten edustajia sekä alan asiantuntijoita. Sivuvirtojen teknisten hyötykäyttömahdollisuuksien ja liiketoiminnallisten mahdollisuuksien tarkastelua varten järjestetään työpajoja asiantuntijoille Apila Group Oy Ab:n asiantuntijaverkostossa. Neljässä haastatellussa tuotantolaitoksissa syntyi vuonna 2008 yhteensä 6 662 tonnia kiinteää jätettä ja lietteitä. 68 % näistä sivuvirroista hyötykäytettiin energiana tai polttoaineen valmistuksessa. Materiaalina sivuvirtoja hyötykäytettiin 16 % sivuvirroista, pääasiassa pahvia, paperia, metalleja sekä tynnyreitä ja kontteja. Myös merkittävä osa liuottimista otettiin talteen uudelleenhyödyntämistä varten. Tässä diplomityössä hyötykäyttömahdollisuuksien tarkempaa tarkastelua varten valittiin tavanomaisiksi jätteiksi luokiteltuja maalisivuvirtoja, joita haastatelluissa tuotantolaitoksissa syntyi noin 1 500 tonnia. Maalisivuvirtojen tärkeimmät materiaaliominaisuudet liittyvät niiden sisältämiin täyte- ja sideaineisiin, jotka muodostavat merkittävän osan maalien koostumuksesta. Selvityksen mukaan nämä ominaisuudet voidaan ottaa hyötykäyttöön erilaisissa yhdistelmämateriaaleissa, esimerkiksi ekstruusiopuristetuissa tai ahtopuristetuissa muovikuitukomposiiteissa. Komposiittien raaka-aineena käytetään jo erilaisia sivuvirtoja ja lisäksi erilaisten komposiittien markkinoiden ennustetaan kasvavan. Tämä voi tarjota mahdollisuuksia uusille palvelu-, t&k- tai tuotteistusliiketoiminnoille. Kuivilla maalijätteillä on myös hyvä lämpöarvo, jolloin energiahyötykäytön ja palamisjäännöksen materiaalihyötykäytön yhdistäminen mm. keramiikka- tai sementtiteollisuudessa voi tarjota mahdollisuuksia uusille liiketoiminnoille.

Rigid Rod Polymer Fillers in Acrylic Denture and Dental Adhesive Resin Systems

Polymeric materials have been used in dental applications for decades. Adhesion of polymeric materials to each other and to the tooth substrate is essential to their successful use. The aim of this series of studies was two-folded. First, to improve adhesion of poly(paraphenylene) based rigid rod polymer (RRP) to other dental polymers, and secondly, to evaluate the usability of a new dentin primer system based on RRP fillers. Poly(paraphenylene) based RRP would be a tempting material for dental applications because of its good mechanical properties. To be used in dental applications, reliable adhesion between RRP and other dental polymers is required. In this series of studies, the adhesion of RRP to denture base polymer and the mechanical properties of RRP-denture base polymer-material combination were evaluated. Also adhesion of BisGMA-TEGDMA-resin to RRP was determined. Different surface treatments were tested to improve the adhesion of BisGMA-TEGDMA-resin to RRP. Results were based on three-point bending testing, Vickers surface hardness test and scanning electron microscope analysis (SEM), which showed that no reliable adhesion between RRP and denture base polymer was formed. Addition of RRP filler to denture base polymer increased surface hardness and flexural modulus but flexural strength decreased. Results from the shear bond strength test and SEM revealed that adhesion between resin and RRP was possible to improve by surface treatment with dichloromethane (DCM) based primer and a new kind of adhesive surface can be designed. The current dentin bonding agents have good immediate bond strength, but in long term the bond strength may decrease due to the detrimental effect of water and perhaps by matrix metalloproteinases. This leads to problems in longevity of restorations. Current bonding agents use organic monomers. In this series of studies, RRP filled dentin primer was tested in order to decrease the water sorption of the monomer system of the primers. The properties of new dentin primer system were evaluated in vitro by comparing it to commercial etch and rinse adhesive system. The results from the contact angle measurements and SEM showed that experimental primer with RRP reinforcement provided similar resin infiltration to dentin collagen and formed the resin-dentin interface as the control primer. Microtensile bond strength test and SEM revealed that in short term water storing, RRP increased bond strength and primer with BMEP-monomer (bis[2-(methacryloyloxy)-ethyl]phosphate) and high solvent concentration provided comparable bonding properties to the commercial control primers. In long term water storing, the high solvent-monomer concentration of the experimental primers decreased bond strength. However, in low solvent-monomer concentration groups, the long-term water storing did not decrease the bond strength despite the existence of hydrophilic monomers which were used in the system. These studies demonstrated that new dentin primer system reached the mechanical properties of current traditional etch and rinse adhesive system in short time water storing. Improved properties can be achieved by further modifications of the monomer system. Studies of the adhesion of RRP to other polymers suggest that adhesion between RRP and other dental polymers is possible to obtain by certain surface treatments.

Synthesis and characterization of Fe(III)-doped ceramic membranes of titanium dioxide and its application in photoelectrocatalysis of a textile dye

Pure and Fe(III)-doped TiO2 suspensions were prepared by the sol gel method with the use of titanium isopropoxide (Ti(OPri)4) as precursor material. The properties of doped materials were compared to TiO2 properties based on the characterization by thermal analysis (TG-DTA and DSC), X-ray powder diffractometry and spectroscopy measurements (FTIR). Both undoped and doped TiO2 suspensions were used to coat metallic substrate as a mean to make thin-film electrodes. Thermal treatment of the precursors at 400ºC for 2 h in air resulted in the formation of nanocrystalline anatase TiO2. The thin-film electrodes were tested with respect to their photocatalytic performance for degradation of a textile dye in aqueous solution. The plain TiO2 remains as the best catalyst at the conditions used in this report.

Influence of topography and surface chemistry on the wetting properties of TiO2-based ceramic coatings

Vätning av fasta ytor är ett viktigt fenomen i såväl naturen som i en lång rad av industriella tillämpningar. Det är allmänt känt att vätningen av en fast yta styrs av ytans kemi samt struktur. Målsättningen med avhandlingen var att studera hur kemisk heterogenitet och ytråhet på nanometernivå påverkar vätningsegenskaperna hos en fast yta. Ytorna som studerades var titandioxid-baserade kerama ytor som framställdes med hjälp av en sol-gel process. Vätningstudierna utfördes genom kontaktvinkelmätningar, vilket innebär att man mäter vinkeln som vätska/luft-gränsskiktet hos en vätskedroppe bildar mot en fast yta. Ytråheten hos materialen studerades främst genom atomkraftsmikroskopi (AFM). I AFM detekteras ytans struktur av en mycket skarp nål som skannar ytan. Resultaten i avhandlingen kunde framgångsrikt modelleras med existerande teorier för vätning av heterogena ytor.

Formation of polyelectrolyte multilayers and polyelectrolyte complexes in dual polymer treatment of papermaking pulp

The goal of this study was to find a new approach to modify chemically the properties of paper by improving fiber quality. This Master’s thesis includes the multiple polymer treatment in general and themeasurement methods with which the formation of multilayers and complexes can be noticed. The treatment by an oppositely charged dual polymer system is a good approach to increase paper strength. In this work, starch, a cationic polymer, and carboxymethyl cellulose (CMC), an anionic polymer, were used step-by-step to improve paper strength. The adsorption of cationic starch and CMC on cellulose fibers were analyzed via polyelectrolyte titration. The results showed that paper strength was enhanced slightly with a layer-by-layer assembly of the polymers. However, if the washing stage, which was required for layer-by-layer assembly, was eliminated, the starch/CMC complex was deposited on fibers more efficiently, and the paper strength was improved more significantly.