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Preparation of carbon nanotube embedded in polyacrylonitrile (PAN) nanofibre composites by electrospinning process

Pilehrood M. K., Heikkilä P., Harlin A.

Autex Research Journal

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2012

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Vol. 12, no. 1

1--6

EN

Polyacrylonitrile (PAN) nanofibres and carbon nanotube (CNT) reinforced PAN nanofibres were successfully electrospun. A polymer plasticiser, ethylene carbonate (EC), was added into the PAN/CNT solutions. The average diameter of the fibres varied between 80 and 240 nm. This study investigated the effects of polymer concentration, CNT and EC on the morphological characteristics of electrospun PAN fibres. Electrospinning parameters were set at constant values to prevent their mutual influences on the resultant morphology. It was observed that increasing the polymer concentration led to a reduction of beads density and an increase in the diameter of the PAN nanofibres. The fibre diameters also increased as a result of the addition of CNTs below the electrical percolation threshold. It was found that the inclusion of EC permits changes in the morphological characteristic of the PAN/CNT nanocomposite fibre regardless of the effects of its conductivity and viscosity.

2

Fast and efficient surface treatment for nonwoven materials by atmospheric pressure plasma

Väänänen R., Heikkilä P., Tuominen M., Kuusipalo J, Harlin A.

Autex Research Journal

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2010

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Vol. 10, no. 1

8--13

EN

Plasma treatments can be used for the nano-scale surface modification of different materials including nonwovens. Penetration of plasma into solid matter is very limited, but it can penetrate into porous structures. Therefore plasma can be used to modify not only the outer surface, but also the surfaces of fibres within and the other side of the porous structure of nonwoven material. The purpose of this study was to examine the feasibility of continuous atmospheric plasma treatment for the modification of porous nonwoven materials. Firstly, the penetration of plasma through layered, porous samples, and secondly, the effect of the plasma exposure time on the surface properties and mechanical properties of the samples were studied. We found that the plasma penetrated through three nonwoven layers. It also seemed that the plasma was retained inside the samples for a while after initial exposure, thus increasing the effective exposure time. An increase of exposure time further by controlling line speed did not have significant influence on the efficiency of the treatment. The mechanical properties of the material were not prominently affected by the treatment. Our results suggest that it is possible to conduct twosided plasma treatment on porous nonwoven materials as a continuous process with a speed feasible to be combined with conventional textile processing.

3

Simulation of a rapid nip pressure strike and its effect on press felt samples

Hakala T., Harlin A.

Autex Research Journal

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2008

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Vol. 8, no. 3

84--91

EN

Special technical textiles are used in papermaking to support, transfer, and dewater the paper web. These textiles, paper machine cloths, have many essential functions connected to their position on the paper or board machine. Mechanical wet pressing uses press felts, whose porosity and resiliency are important for effective dewatering. Water is squeezed out by two overlapping paper machine rolls, which form a nip. After squeezing, the porous felt should be void and return to its original thickness to ensure efficient dewatering. Friction forces are also present at the nip, since abrasive interfaces occur between the cloths and the rolls by pressure, heat, and movement. Thus in time, the harsh papermaking process wears out the press felt, deteriorating its quality. At high machine speed, defects in press felts, rolls, or other parts of the nip environment can cause runnability problems such as noisy run, that is, vibration in the pressing section, decreasing paper quality and output capacity. This study sought for a new way to simulate the ambiguous nip phenomenon on laboratory scale and to find out a way to predict this noisy run problem. A dynamic test method, the Hopkinson Split Bar, was used to define the ease with which strike energy passed through from the upper roll to the lower roll and the damping of strikes by new and worn felt samples. In our study, the elasticity of the press felt was strongly linked with the ageing time. Decreased elasticity lets a nip impulse more easily through the press felt.

4

Electrospun nanofibers prepared by two methods: in situ emulsion polymerized PVA/nano TiO2 and mixing of functional-PVA with nano TiO2

Ristolainen N., Heikkilä P., Harlin A., Seppälä J.

Autex Research Journal

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2008

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Vol. 8, no. 2

35--40

EN

Poly(vinyl alcohol)/nano-sized titanium dioxide (PVA/nanoTiO2) water dispersions were electrospun in order to prepare networks of polymer composite nanofiber for coating applications. In particular, the effect of the functionalization of the polymer matrix, coating of the filler particles, and the preparation method of the polymer dispersions on the nanoparticle distribution along the resulting fibers were studied. The dispersions were prepared using two different techniques: batch in situ emulsion polymerization and mixing methods. Differently coated hydrophilic nanoTiO2 particles were used on one hand, and on the other, pure PVA and carboxyl- and silanol-functionalized PVAs were used. Dispersion properties were assessed by measuring viscosity and estimating the degree of homogeneity before electrospinning. The structure of the electrospun fibers was studied using scanning electron microscopy and elemental analysis. It was observed that the dispersion properties differed substantially depending on the types of polymer and filler particles used. Electrospinning succeeded in forming continuous fibers instead of separate droplets with all except one type of PVA/nanoTiO2 dispersions. It was confirmed that the resulting fibers and droplets contained nanoTiO2 particles. For the in situ polymerized dispersions the filler distribution in the resulting fibers was strongly influenced by the nanoparticle coating. In the mixing method, the resulting nanoparticle distribution was affected primarily by the polymer type used, and the role of the nanoparticle coating was not important.

5

Laboratory ageing test device for press-felt clothes of paper machine

Hakala T., Wilenius T., Harlin A.

Autex Research Journal

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2007

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Vol. 7, no. 1

70--79

EN

The main part of the de-watering process in a paper machine (PM) is carried out by means of mechanical pressing, which considerably influences the paper quality and energy efficiency of the paper machine. This paper discusses a method for controlled press-felt mechanical degradation. For our research, a special test device was designed and developed to simulate press-felt ageing in the pressing section of paper machines. All the described methods and tests were carried out in the Institute of Fibre Materials Science at Tampere University of Technology.

6

Manufacturing methods for multi step index plastic optical fiber materials

Ferenets M., Myllymäki H., Grahn K., Sipilä A., Harlin A.

Autex Research Journal

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2004

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Vol. 4, no. 4

163--173

EN

Plastic optical fibres (POF) are often used in telecommunication, consumer electronics and automotive applications. Measuring and control devices used for POF are already standardised procedures. To meet the requirements of the IEEE 1394 standard for data transfer rates up to 800Mbps requires increasingly improved performance of POF. POFs which offer high bandwidth, total electromagnetic immunity and simple handling are considered as an alternative to noisy copper cables (cat 5) and high performance glass optic fibres for of a data highway. The market requires a simple and inexpensive alternative that would not be a technical overkill. The target of the study carried out in the Institute of Fibre Materials Science at Tampere University of Technology was to evaluate manufacturing methods which would allow this. This is a summary article of the results of manufacturing step index and multi-step index POF by preform manufacturing followed by fibre drawing as well as the extrusion method.

7

Development of polymeric optical fibre fabrics as illumination elements and textile displays

Harlin A., Mäkinen M., Vuorivirta A.

Autex Research Journal

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2003

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Vol. 3, no. 1

1--8

EN

Polymeric optical fibre (POF) is used for simple light guide and illumination applications. The polymer optical fibre materials can be utilised in flexible lighting elements which can be combined with textile structures. The POF woven fabrics are introduced as a flexible alternative to lighting elements. Various light-emitting woven fabric and light emission theories has been discussed. Simple poly-methyl-metacrylate PMMA and polycarbonate PC fibres have been produced experimentally through single-screw and conical extrusion. The fibre is integrated in woven structures by means of handloom, narrow fabric weaving and Jacquard technology. The manufacturing technology suitable for light- emitting textile applications and its opportunities in textile integration is discussed.

8

Polymeric optical fibres and future prospects in textile integration

Harlin A., Myllymäki H., Grahn K.

Autex Research Journal

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2002

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Vol. 2, no. 3

132--143

EN

In the era of wearable computing, intelligent systems are breaking the bounds of traditional textiles and their design. The integration of the technologies with clothing, accessories, upholstery, or industrial technical textiles provides higher user-comfort and enables their seamless use in everyday activities. Polymer optical fibre materials are suitable for short-distance data transfer and can be combined with textile structures. The manufacture of the fibre is low cost, and the products are more durable than glass optic fibres. Applications for POF today are known in the automotive industry, consumer electronics, cabling, and measuring as optodes. Polymeric optical fibre (POF) made of PMMA has been on the market for the past 25 years, used for simple light guide and data transmission application. Perfluor polymers (PF) offer great new opportunities in the field of data communication because of low absorption losses. Optical polycarbonate (PC), and polystyrene (PS) are used for special applications. The POF materials are introduced, and their opportunities in textile integration are discussed.