Browsing by Author "Spoljaric, Steven"

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Chemical compatibility of fused filament fabrication-based 3-D printed components with solutions commonly used in semiconductor wet processing
(2018-10-01) Heikkinen, Ismo T.S.; Kauppinen, Christoffer; Liu, Zhengjun; Asikainen, Sanja M.; Spoljaric, Steven; Seppälä, Jukka V.; Savin, Hele; Pearce, Joshua M.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
3-D printing shows great potential in laboratories for making customized labware and reaction vessels. In addition, affordable fused filament fabrication (FFF)-based 3-D printing has successfully produced high-quality and affordable scientific equipment, focusing on tools without strict chemical compatibility limitations. As the additives and colorants used in 3-D printing filaments are proprietary, their compatibility with common chemicals is unknown, which has prevented their widespread use in laboratory chemical processing. In this study, the compatibility of ten widely available FFF plastics with solvents, acids, bases and solutions used in the wet processing of semiconductor materials is explored. The results provide data on materials unavailable in the literature and the chemical properties of 3-D printable plastics that were, are in line with literature. Overall, many 3-D printable plastics are compatible with concentrated solutions. Polypropylene emerged as a promising 3-D printable material for semiconductor processing due to its tolerance of strongly oxidizing acids, such as nitric and sulfuric acids. In addition, 3-D printed custom tools were demonstrated for a range of wet processing applications. The results show that 3-D printed plastics are potential materials for bespoke chemically resistant labware at less than 10% of the cost of such purchased tools. However, further studies are required to ascertain if such materials are fully compatible with clean room processing.
Cyclodextrin-Functionalized Fiber Yarns Spun from Deep Eutectic Cellulose Solutions for Nonspecific Hormone Capture in Aqueous Matrices
(2018-02-12) Orelma, Hannes; Virtanen, Tommi; Spoljaric, Steven; Lehmonen, Jani; Seppälä, Jukka; Rojas, Orlando J.; Harlin, Ali
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
A wood based yarn platform for capturing pharmaceutical molecules from water was developed. Cellulose fiber yarns were modified with cyclodextrins, and the capture of 17α-ethinyl estradiol (EE2), a synthetic estrogen hormone used as contraceptive, from water was tested. The yarns were prepared by spinning a deep eutectic solution (DES) of cellulose in choline chloride-urea. Despite their high porosity and water sorption capacity (5 g/g), the spun fiber yarns displayed high wet strength, up to 60% of that recorded in dry condition (128 MPa with 17% strain at break). Cyclodextrin irreversible attachment on the yarns was achieved with adsorbed chitosan and the conjugation reactions and capture of EE2 by the cyclodextrin-modified cellulose were confirmed via online detection with Surface Plasmon Resonance (SPR). The facile synthesis of the bioactive yarns and EE2 binding capacity from aqueous matrices (as high as 2.5 mg/g) indicate excellent prospects for inexpensive platforms in disposable affinity filtration. The study presents a strategy to produce a wood fiber based yarn to be used as a platform for human and veterinary pharmaceutical hormone capture.
Effects of water soaking-drying cycles on thermally modified spruce wood-plastic composites
(2020-01-01) Kallbom, Susanna; Lillqvist, Kristiina; Spoljaric, Steven; Seppälä, Jukka; Segerholm, Kristoffer; Rautkari, Lauri; Hughes, Mark; Walinder, Magnus
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The overall aim of this work was to gain more insight on the potential of modified wood (TMW) components for use in wood-thermoplastic composites (WPCs). Laboratory-scale TMWPCs were produced, and the effects of severe water soaking-drying cycles on the samples were studied. Water sorption behavior and resulting dimensional and micromorphological changes were also studied, and the results were compared with those of unmodified wood-plastic composites (UWPCs) used as control. The TMW was prepared by cutting a spruce board into half and subjecting one-half to an atmosphere of superheated steam at atmospheric pressure with a peak temperature of 210°C, with the other unmodified wood (UW) half as a control. The TMW and UW components were then prepared by a Wiley mill and thereafter sifted into smaller (mesh 0.20-0.40 mm) and larger (mesh 0.40-0.63 mm) size fractions. A portion of the wood components were also subjected to hydrothermal extraction (HE). Composite samples with these different wood components, polypropylene (PP) matrix, and maleated PP (MAPP) as coupling agent (50/48/2 wood/PP/ MAPP ratio by weight) were then prepared by using a Brabender mixer followed by hot pressing. The matching micromorphology of the composites before and after the soaking-drying cycles was analyzed using a surface preparation technique based on ultraviolet-laser ablation combined with scanning electron microscopy. The results of the water absorption tests showed, as hypothesized, a significantly reduced water absorption and resulting thickness swelling at the end of a soaking cycle for the TMWPCs compared with the controls (UWPCs). The water absorption was reduced with about 50-70% for TMWPC and 60-75% for HETMWPC. The thickness swelling for TMWPCs was reduced with about 40-70% compared with the controls. Similarly, the WPCs with HE-UW components absorbed about 20-45% less moisture and showed a reduced thickness swelling of about 25-40% compared with the controls. These observations also were in agreement with the micromorphology analysis of the composites before and after the moisture cycling which showed a more pronounced wood-plastic interfacial cracking (de-bonding) as well as other microstructure changes in the controls compared with those prepared with TMW and HE-UW components. Based on these observations, it is suggested that these potential bio-based building materials show increased potential durability for applications in harsh outdoor environments, in particular TMWPCs with a well-defined and comparably small size fractions of TMW components.
In situ small angle X-ray scattering investigation of the thermal expansion and related structural information of carbon nanotube composites
(2012-12) Dumee, Ludovic; Thornton, Aaron; Sears, Kallista; Schuetz, Juerg; Finn, Niall; Spoljaric, Steven; Shanks, Robert; Skourtis, Chris; Duke, Mikel; Gray, Stephen
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
In-situ thermal expansion tests on a series of carbon nanotube bucky-paper composites were performed with direct heating within a synchrotron SAXS source. The impact of the samples density and morphology as well as the chemistry and degree of decoration of the carbon nanotubes on the scattering patterns were investigated and correlated to the materials macro-properties. The results demonstrate that simple densification techniques, such as acetone dipping or gold electroless deposition, could reduce greatly the displacements of the carbon nanotubes within the structure and lead to more thermally stable material. (c) 2012 Chinese Materials Research Society. Production and hosting by Elsevier Ltd. All rights reserved.
Novel pulp fibres for mouldable materials
(2017-01-09) Modig, Sakari
Kemian tekniikan korkeakoulu | Master's thesis
Redefining polyamide property profiles via renewable long-chain aliphatic segments: Towards impact resistance and low water absorption
(2018-12-01) Nguyen, Phan Huy; Spoljaric, Steven; Seppälä, Jukka
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
A series of renewable, long-chain, fatty acid-derived polyamides (PA) ranging from PA 6,14 to PA 6,18 were synthesized via polycondensation, yielding very high molecular weights and a remarkable property profile distinct from short-chain commercial grades. Most notably, synthesized polyamides exhibited good impact resistance, excellent stiffness-to-toughness balance and very low water absorption yet high oxygen and water vapour permeability; with this property profile being exemplified by PA 6,18. The increased repeating unit length and reduced number of amide linkages able to participate in interchain hydrogen bonding imparted a strong influence on material properties. The data highlights the benefits and technical advantages of utilising long-chain polyamides, while also significantly expanding the repertoire, knowledge and property profile of the long-chain aliphatic polyamide family, and providing a basis for further development of polyamides from renewable sources.
Renewable polyamides via thiol-ene ‘click’ chemistry and long-chain aliphatic segments
(2018-09-26) Nguyen, Phan Huy; Spoljaric, Steven; Seppälä, Jukka
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Thiol-ene ‘click’ chemistry was utilised to prepare dicarboxylic acid monomers containing two sulphur units within the backbone, which subsequently underwent polycondensation to yield a series of renewable, long-chain, fatty-acid derived linear polyamides. The linear sulphur-containing polyamides displayed number-average molecular weights of 8000–55,000 g·mol−1 and broad polydispersities biased towards higher weight fractions. Glass transition values were slightly above room temperature (31–35 °C), while melting temperatures ranged from 121 to 170 °C. This novel class of polymers exhibited an impressive property profile, most notably exceptional impact resistance, tear strength, high elasticity, very low water absorption yet high oxygen- and water vapour permeability. The presence of sulphur and the increased aliphatic segment length influenced a wide spectrum of polyamide properties due to the reduced amide linkage (and inter-chain hydrogen bonding) density and less-effective chain packing ability due to the increased atomic radii of the sulphur atoms. The data highlights the technical advantages of these polymers, while also expanding the repertoire and structure-property relationships of both long-chain- and sulphur-containing polyamides, and encouraging further development of polyamide derivatives from renewable sources.
Rheological considerations in processing nanofibrillated cellulose in gel spinning
(2017-08-29) Hautaviita, Tanja
Kemian tekniikan korkeakoulu | Master's thesis
Spinning dopes based on nanofibrillated cellulose (CNF) and poly(vinyl alcohol) (PVA) were characterized to determine correlations between spinnability and rheological properties. Spinnability is important factor presenting the ability and ease of filament formation and if rheology can be related to it, it will help designing better dopes for enhanced spinnability. The demand for more renewable products is increasing thus this work studies the use of 1:1 CNF to matrix dopes, where matrix stabilizes the filament and improves the tensile properties. Previous works commonly use much smaller CNF concentrations and eventhough the rheology of CNFs is well studied it hasn’t been correlated to the spinnability. The effect of dopes consistency to the rheology were tested by changing the solids content from 2 to 4 wt% and altering the matrix composition. The PVA matrix was used as the baseline for all measurements when the effect of adding guar and glutaraldehyde (GA) were tested. Guar was added to increase the high molecular weight portion, that has previously been found to increase spinnability. GA instead was used to study the ability to crosslink the filaments. The crosslinking was tested having the acid in the coagulation bath or in the dope. Thus the effect of acidic and neutral bath were also studied. As crosslinking occurs after the spinning it cannot be related to the rheological properties. Specific rheological measurements (amplitude and frequency sweep and steady state shear) were used to characterize the dopes; this was correlated with observed spinnability. The spinnability qualifications were the wet properties derived from previous gel spinning experiments and the ease of spinning and the tensile properties of the formed filament. Additionally filaments were visually estimated and tested for possible crosslinking. The best correlation to spinnability of these gel dopes came from the gel strength calculated from the amplitude sweep measurement. The increasing gel strength improved filament stability in the free suface flow. In the air gap filaments started retain the shape attained in capillary with the gel strength of 35 – 45 Pa. Even higher gel strength of 60 – 80 Pa was required for the filament to be enough stable to continue into the bath via an air gap. The storage modulus values instead with the knowledge of the expected entanglement degree allowed the estimation of successful formation of inner structure. This allowed the observation of poor CNF dispersion in the 4 wt% dope containing guar. The linear viscoelasticity region (LVR) instead explained the increased solid like behavior of some of the dope compositions and why they failed to form continuous filament even if they formed filament in the air gap. These parameters were the best for comparing dopes and spinnability. Other parameters gave further insights to the differences between the dopes, but had less effect to the observed spinnability.
Stable, self-healing hydrogels from nanofibrillated cellulose, poly(vinyl alcohol) and borax via reversible crosslinking
(2014) Spoljaric, Steven; Salminen, Arto; Luong, Nguyen Dang; Seppälä, Jukka
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä