Yarn hairiness affects not only the quality of products, but also the productivity in spinning and weaving. Too much yarn hairiness is undesirable for many end uses as well as the spinning and post spinning processes. The main aims of this project are to examine the hairiness features of various yarns and to reduce yarn hairiness. The thesis covers five related areas – hairiness assessment, factors affecting yarn hairiness, the hairiness of newly developed yarns, yarn hairiness reduction, and effect of yarn hairiness on the energy consumption in ring spinning. The worsted cashmere, pure wool and wool/cashmere blend yarns were employed to investigate the effect of some fibre parameters on the yarn hairiness. A single exponential distribution of the hair-length was confirmed first, using the data from the Zweigle G565 Hairiness Meter. A linear relationship was observed between the blend ratio and the hairiness indexes. In particular, the effect of fibre crimp or curvature on yarn hairiness is examined. The theory of yarn hairiness composition was also developed further. The effect of draft ratio and spindle speed on the hairiness of worsted wool yarn was examined next with a factorial experiment design. Several new hairiness indexes, namely the relative hairiness indexes, have been used to explain the results obtained. In the investigation of the hairiness of newly developed yarns, the hairiness of the Compact Spun and Roller-Jet-Spun yarns was examined first. The composition of the yarn hairiness, the hair-length distribution, and the effect of test speed on yarn hairiness were then studied. An important finding is that for both yarns, the predominant hairiness feature is the looped hairs. A comparison of the hairiness of Solospun yarns and the equivalent ring spun wool yarns was undertaken. The hair-length distribution of the Solospun yarn was examined first. The Solospun yarns used had fewer hairs in most hair-length groups and lower variations in hairiness. In addition, the effect of twist level and spindle speed on the hairiness of Solospun and conventional ring spun yarns has also been discussed. A novel approach of reducing yarn hairiness – spinning with a ‘Diagonal’ yarn path was examined next. Both ‘Left Diagonal’ and ‘Right Diagonal’ yarn arrangements were studied. A new finding is that the ‘Right Diagonal’ yarn path leads to reduced hairiness for the Z-twist yarn, while yarn evenness and tenacity are not as sensitive to the modified yarn path. The mechanism of hairiness reduction with the ‘Diagonal’ yarn path has been discussed. The spinning performance of “Right Diagonal” yarn arrangement has also been evaluated. Finally, the effect of yarn hairiness on the energy consumption in ring spinning has been investigated theoretically and experimentally. A theoretical model has been developed, which represents the first attempt at theoretically investigating the influence of yarn hairiness on energy consumption during the winding stage of ring spinning. The experimental results have generally confirmed predictions of this model. Recommendations for further research in this area have also been made in the concluding chapter of this thesis.

Made available in DSpace on 2014-12-17T14:58:22Z (GMT). No. of bitstreams: 1 ClaraSS_DISSERT.pdf: 3432218 bytes, checksum: 7e008670903eeebdf6b98724b154b050 (MD5) Previous issue date: 2011-10-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Cotton is a hydrofilic textile fiber and, for this reason, it changes its properties according to the environment changes. Moisture and Temperature are the two most important factors that lead a cotton Spinning sector and influence its quality. Those two properties can change the entire Spinning process. Understanding this, moisture and temperature must be kept under control when used during the Spinning process, once the environment is hot and dry, the cotton yarns absorb moisture and lose the minimal consistency. According to this information, this paper was developed testing four types of cotton yarns, one kind of cotton from Brazil and the others from Egypt. The yarns were exposed to different temperatures and moisture in five different tests and in each test, six samples that were examined through physical and mechanical tests: resistance, strength, tenacity, yarn?s hairness, yarn?s evenness and yarn?s twisting. All the analysis were accomplished at Laborat?rio de Mec?nica dos Flu?dos and at COATS Corrente S.A., where, it was possible to use the equipments whose were fundamental to develop this paper, such as the STATIMAT ME that measures strength, tenacity, Zweigler G566, that measure hairiness in the yarn, a skein machine and a twisting machine. The analysis revealed alterations in the yarn?s characteristics in a direct way, for example, as moisture and temperature were increased, the yarn?s strength, tenacity and hairness were increased as well. Having the results of all analysis, it is possible to say that a relatively low temperature and a high humidity, cotton yarns have the best performance / O algod?o ? uma fibra t?xtil hidr?fila e por essa raz?o muda suas caracter?sticas em fun??o das condi??es do ambiente. A umidade e a temperatura s?o dois fatores que influenciam o ambiente de uma fia??o de algod?o. Estes dois fatores podem alterar a qualidade de toda uma produ??o de fios. Sendo assim, umidade e temperatura devem ser mantidas sob o controle para o processamento do algod?o, uma vez que em um ambiente seco e quente os fios de algod?o liberam umidade e se rompem, aumentando o ?ndice de quebra da fia??o com o ambiente frio e ?mido, os fios absorvem umidade e perdem a consist?ncia m?nima.Com base nessas informa??es, este trabalho foi desenvolvido experimentando quatro tipos de fio de algod?o sendo de origem brasileira e os demais, de origem eg?pcia. Os fios foram expostos a temperatura e umidade diferentes em cinco experimentos distintos, contendo cada experimento seis amostras que passaram por testes f?sicos e mec?nicos: resist?ncia, for?a, tenacidade, pilosidade, t?tulo e tor??o. As an?lises foram realizadas no Laborat?rio de Mec?nica dos Fluidos na Universidade Federal do Rio Grande do Norte e na empresa COATS Corrente S.A., onde foi poss?vel fazer uso dos equipamentos fundamentais para o desenvolvimento deste trabalho, tais como o STATIMAT ME que mede a resist?ncia, for?a e tenacidade do fio, Zweigler G566 o qual mensurou a quantidade de pilosidade no fio e, a meadeira e o torc?metro, respons?veis pelo t?tulo e tor??o. As an?lises revelaram altera??es nas caracter?sticas dos fios de forma diretamente proporcional, como por exemplo, conforme aumentava-se a umidade e temperatura havia um aumento da resist?ncia, for?a, tenacidade e pilosidade. Em posse desses resultados, ? poss?vel afirmar que a uma temperatura relativamente baixa e uma umidade alta, os fios de algod?o tem sua performance m?xima