Band 10, Heft 4

Disc spinning is a new spinning technique that is still under investigation in many research institutes and universities. It is not yet a commercial system, although it is promising. The appearance of the outer layer of produced yarns is similar to that of ring spinning, but is produced at higher rates. It includes the major spinning stages such as fibre opening, feeding to the forming zone and yarn consolidation by twisting, then yarn winding. Opened fibres are condensed on the outer surface of a rotating screened surface disc and simultaneously twisted by using an external twister. Air suction acts through a slit located just beneath the screened surface at a certain angle that controls the laying angle of the fibre bundle on the screened surface. The formed yarn is then drawn at a predetermined angle with respect to the slit direction. It is suggested that both slit angle and the direction of the withdrawal of the yarn during its formation with respect to the slit affect fibre extent on the forming zone and, accordingly, yarn properties. Papers about this new technique are limited, especially those considering the effect of design parameters on fibre straightening during yarn formation. In this article, parameters expected to affect fibre extent in the forming zone during yarn formation were suggested and treated theoretically to maximise fibre straightening during yarn formation.

In many technical applications, fibre-reinforced composites with textile high-performance fibres made of carbon or glass are being used. The fibres qualify for their high strength and stiffness due to their physical and chemical characteristics. It is necessary to guarantee a high safety level under all possible loading constellations. Besides the usual service loads, the topic of extreme loads that work along with high forces and high impact velocity is of increasing importance. For these so-called impact loads, the processes within the structural components have to be analysed and material models suitable for prognoses should be derived from them. The existence of suitable test machines and test methods is a prerequisite for that, yet for filament yarns they are not state of the art. Hence, tensile tests with high strain rates on filament yarns are performed on standard high-speed tensile testing machines. This leads to problems when analysing and interpreting the results and therefore, it is necessary to develop special testing machines for filament yarns.

This paper deals with the modelling of the heat transfer process in a thin porous fibrous material such as a paper sheet when it is subjected to an incident heat flux introduced by a laser beam. A mathematical model based on the control volume principle is developed for numerical estimation of radial temperature distribution which is validated experimentally by infrared thermography. Here the heat flux is introduced by a CO2 laser beam of 10.6 μm wavelength and an infrared image sequence is recorded as a function of time with a high resolution infrared camera. The preliminary validation results indicate that the simulation model can predict the transient development of sheet temperature very accurately under the specified heating conditions. The model can enhance our understanding and insights of the heat transfer process in such media, which is of great interest for many drying and thermal applications. Though the application shown here is on a 0.1 mm thick paper sheet, the model can be extended to any thin porous fibrous media such as textiles and nonwovens.

The modification of paper substrates by organic nanoparticle coatings offers an attractive alternative for creating hydrophobic and water-repellent surfaces without fluorinated chemicals. The nanoparticles were synthesized by imidization of poly(styrene-maleic anhydride) and applied to a standard paper grade by means of a laboratory bar-coating process. The effects of supplementary heat treatments of the coated papers were investigated in terms of coating morphology and hydrophobicity: a unique coating structure is formed with a combination of microdomains that are internally structured at the nanoscale. The relatively high glass transition temperature of the nanoparticles allows for good thermal stability of the coating with almost no morphological changes at heating up to 180°C. The changes in chemical composition were investigated by diffuse reflectance infrared spectroscopy (DRIFT) and UV/VIS spectroscopy. The latter techniques qualitatively describe the effects of thermal treatments on the imide and styrene moieties. Contact angle measurements indicate that there is an optimum curing temperature in order to obtain a maximum advancing contact angle of 133° to 150°.

In this research, fuzzy modelling and neural network methods were used and compared to predict the residual bagging bend height of knitting fabric samples. Studies undertaken to minimize the bagging phenomenon vary significantly with the test conditions including the experimental field of interest, the input parameters and the applied method. Hence, we attempt to formulate a theoretical model of predicting bagging behaviour in our experimental design of interest. By analysing the bend height of overall bagging samples, this paper provides an effective neural network model to evaluate and predict the residual bagging bend height of the knitting specimens after test. It also provides the impact of each input parameter in our experimental field of interest to simulate this phenomenon after use. Moreover, the contribution of these influential input parameters was analysed and discussed. Nevertheless, our results show that residual bagging height decreases when yarn contains elastane filament, Spandex©. This finding is in agreement with Mirostawa et al. [11] that with an increase of the elastane content in fabric, permanent bagging decreases, whereas elastic bagging increases. According to the analytical results obtained, the neural network model gives a more accurate prediction than the fuzzy one.