Zoekresultaten

µPlasma printing of hydrophobic and hydrophilic patterns to improve wetting behaviour for printed electronics

Inkjet printing is a rapidly growing technology for depositing functional materials in the production of organic electronics. Challenges lie among others in the printing of high resolution patterns with high aspect ratio of functional materials to obtain the needed functionality like e.g. conductivity. μPlasma printing is a technology which combines atmospheric plasma treatment with the versatility of digital on demand printing technology to selectively change the wetting behaviour of materials. In earlier research it was shown that with μPlasma printing it is possible to selectively improve the wetting behaviour of functional inks on polymer substrates using atmospheric air plasma. In this investigation we show it is possible to selectively change the substrate wetting behaviour using combinations of different plasmas and patterned printing. For air and nitrogen plasmas, increased wetting of printed materials could be achieved on both polycarbonate and glass substrates. A minimal track width of 320 μm for a 200 μm wide plasma needle was achieved. A combination of N2 with HMDSO plasma increases the contact angle for water up from <100 to 1050 and from 320 to 460 for DEGDMA making the substrate more hydrophobic. Furthermore using N2-plasma in combination with a N2/HMDSO plasma, hydrophobic tracks could be printed with similar minimal track width. Combining both N2 -plasma and N2/HMDSO plasma treatments show promising results to further decrease the track width to even smaller values.

Long term effects of an innovative physics teacher education program in the Philippines

In 1996 innovative, double major teacher education programs for Physics & Mathematics and Physics & Chemistry were initiated at the University of San Carlos in Cebu, Philippines. Both programs require 4 years of study. From the outset the focus was on making a difference in the quality of Science and Mathematics Teacher Education, producing teachers with a good mastery of subject matter and able to teach the subjects in exciting and effective ways in typical Philippine crowded and resource-poor classrooms. The programs recruit top high school graduates using a promotion and scholarship scheme and then expose them to the best science lecturers at the university, and create a special learning environment for the duration of their training. Early 2011 a study was conducted to assess long term effects of the programs through a tracer study of the 300 alumni, interviews, and 22classroom visits to observe their teaching. Of the 300 alumni 245 are still teaching of whom 33 abroad (mainly USA) and 212 in the Philippines. Alumni are highly valued by principals of the top schools in Cebu and their students win many local and even national science competitions. Their teaching is competent with lots of interaction and good subject matter mastery, but they are also facing some typical Philippine education problems.

Productivity and topsoil quality of young and old permanent grassland

Renewing agricultural grasslands for improved yields and forage quality generally involves eliminating standing vegetation with herbicides, ploughing and reseeding. However, grassland renewal may negatively affect soil quality and related ecosystem services. On clay soil in the north of the Netherlands, we measured grass productivity and soil chemical parameters of ‘young’ (5–15 years since last grassland renewal) and ‘old’ (>20 years since last grassland renewal) permanent grasslands, located as pairs at 10 different dairy farms. We found no significant difference with old permanent grassland in herbage dry matter yield and fertilizer nitrogen (N) response, whereas herbage N yield was lower in young permanent grassland. Moreover, the young grassland soil contained less soil organic matter (SOM), soil organic carbon (C) and soil organic N compared to the old grassland soil. Grass productivity was positively correlated with SOM and related parameters such as soil organic C, soil organic N and potentially mineralizable N. We conclude that on clay soils with 70% desirable grasses (i.e., Lolium perenne and Phleum pratense) or more, the presumed yield benefit of grassland renewal is offset by a loss of soil quality (SOM and N-total). The current practice of renewing grassland after 10 years without considering the botanical composition, is counter-productive and not sustainable.

The case of latex removal for carpet and artificial turf recycling

For the recycling of carpet and artificial turf the latex backing is often a real stumble block. Many strategies have been developed like freezing the carpet, followed by grinding and subsequent separation of the milled particles. Once it has been separated from its backing materials, PA 6 is relatively easy to depolymerise. This produces fresh caprolactam that can be used to manufacture PA 6 with no loss in quality, and is suitable for further recycling [1]. The comparable process for PA 6,6 is not as easy, but DuPont and Polyamid 2000 have developed and patented a process that depolymerises any mixture of PA 6 and 6,6 using ammonia. The result is fresh caprolactam and 1,6 diaminohexane for manufacture of PA 6 and 6,6 respectively [2]. Obviously a lot of research has been devoted to avoiding latex as a backing like e.g. polyurethane carpet backing systems based on natural oil polyols and polymer polyols [4]. Still carboxylated styrene butadiene is the leading synthetic latex polymer used in EU-27 for carpet backing, followed by styrene-acrylics and pure acrylics. This contrasts with Eastern Europe, Russia, and Turkey where styrene-acrylics dominate, followed by PVAc and redispersible powders [3]. In addition there has been a lot of research into developing alternative backing systems where the backing can easily be removed. Examples are the use of gecko technology [5] or using click chemistry (reversible Diels Alder reactions) [6]. But the best option for recycling is of course to develop carpets based completely on monomaterials.   Paper for the 14th Autex World Textile Conference May 26th-28th 2014, Bursa, Turkey.

Organization of industrial application of academic research on biocatalytic pre-treatment processes of cotton

A lot of research effort is put in developing enzymatic treatment of textiles by focusing on the performance of enzymes on lab-scale. Despite all this work upgrading of these developments from lab-scale to industrial scale has not been really successful. Companies are nowadays confronted with rapid developments of markets, logistics and social and environmental responsibilities. Moreover these organizations have to supply an evenincreasing amount of information to the authorities, shareholders, lobbyists and pressure groups. Companies have tried to fulfill all these demands, but this led often to the loss of focus on new product and process development. However, both theory and practices of breakthrough innovations has shown that those rightfully proud on previous successes in the past, are usually not the ones that lead the introduction of new technology, aswas shown and excellently documented by Harvard professor Clayton Christensen [Christenson, 2003]. The textile industry is no exception in this observation. With the lack of management impulses on new product and process developments companies began to reduce the investments in these activities. Finally, however, this will result in a reduction of the size of the company or even closing down. Besides the hesitation from the topmanagement of textile companies to focus on new developments it is also seen that the middle management level is reluctant to evaluate and implement developments in new products and processes. One of the reasons for this reluctance is that many processes in textile industry are not fully explored and known yet. From this lack of knowledge it is easy to explain that there is hesitation for changes, since not all consequences of a change inprocessing or production can be overseen. Often new developments cannot be fully tested and evaluated on labor pilot scale level. This is caused by the impossibility to mimic industrial scale production in a lab. Besides of that, pilot scale equipment is very expensive and for many companies it is not realistic to invest in this type of equipment.Fortunately an increasing number of textile companies realize that they have to invest in new products and processes for their future survival and prosperity. New developments are decisive for future successes. If such companies decide to invest in new developments it is obvious that with the scarcity of capital for product- and process developments, the chance of failures should be minimized. For successful process- and product development it is necessary to organize the development process with external partners, as it is clear that it is almost not possible for individual textile companies to control the process from idea generation, academic research, implementation research and development and industrial testing. These issues are specially characteristic for small and medium sized enterprises (SME’s). In the present work the collaboration has been organized on two research levels. The first research level is knowledge and know-how based. Here the universities and the chemical supplier worked closely together to investigate the new process. The aim was to explore the influence of process conditions and interaction of the chemicals in the sub process steps on the result of the treatment. The second level is that of the industrialimplementation of the new process. Here universities and chemical supplier worked closely together with different industries to implement the newly developed process. The focus in this part of the research was the interaction between the chemistry of the new process, equipment and fabrics.A co-operation between the beneficiaries of the new process has been established. The selection criterion for the co-operation was “who will earn something with the new process”. Paper from the Saxion Research Centre for Design and Technology for Proceedings of IPTB Conference, Milan, Italy, M

Process to extract and purify Δ9-tetrahydrocannabinol