Dimensional Stability, Aesthetic and Mechanical Properties of Micro

distribution in the yam structure is being analyzed. The pho- Results tographs below show typical cross-sections of ring and open- The warp break report for the performance of ring-spun yams end yams, respectively. Further work on characterization of is collected for 192 hours of loom running. The approximate fiber distribution is in progress and will be reported time of occurrence of a break is noted which is then used to subsequently. convert to the actual fatigue cycles. This is facilitated by con- sidering the loom speed. The graph below shows the fre- It is obvious from the photographs on the previous page that quency diagram of the number of cycles at which the breaks the two spinning systems impose differing fiber distributions occurred on the loom. Initial study of this diagram suggests in the cross-section. Measurements on the distributions will that a much more complex phenomena is involved in actual be made in the next reporting period when the experimental weaving compared to three parametric Weibull distribution results will be fitted to a theoretical distribution as reported in observed in the laboratory evaluation on the Webtester. Fur- l B.C. Goswami, R.D. Anandjiwala and M. Carmical, Engi- ther work on the analysis of this data is in progress which neering of Fiber PropertiesJor Spinning on Various Sys- will be reported later. tems, J. Appl. Poly. Sci.: Applied Polymer Symposium 47, 464-485, pp 463-485 (1991). Dimensional Stability, Aesthetic and Yarn Performance During Weaving Mechanical Properties of Micro-Fiber Summary: Blended Knitted Fabrics During this quarter the collection of breakage report on per- c92c3 formance of ring-spun yarn has been completed. Also, gait- Principal Investigators: ing and initial setting-up work for open-end yarn beam has Dr. S. Rose Matic-Leigh, Asst. Professor (Clemson) been completed. Loom operation to collect actual performance report of open-end yam beam has been initiated. The Objectives: analysis of breakage report for ring-spun yarn has just com- The main objective of this research is to study and generate menced. After completing this analysis work, attempt will be the information of the microfibers and their blends used in made to compare the actual weaving performance with labo- knitting production. The concept is to use the microfibers ratory evaluation on Sulzer-Ruti Webtester reported in the and their blends with natural fibers to produce knit fabrics previous quarter. with better fabric performance, dimensional stability, and improved aesthetic characteristics. It has already been proven The breakage pattern and incidence of breaks on the loom that microfibers possess a great potential for use in the ap- during weaving of ring-spun yarn has demonstrated that it is parel industry. Most studies and production was done in the important to understand the dynamic tension variation in the weaving area, but there are a lot of indicators that knit fabrics warp yam during weaving. A Tenstec tensiometer will be can be even more improved using microfibers and their used to measure the dynamic tension in the warp yam. It is blends. planned to interface this tension measuring device to a com- puter to continuously measure and plot the dynamic tension Summary: variation on the loom. Dimensional properties of weft knit fabric have long been 20 , I studied in different ways and approach during knit geometry research. The properties of a knitted structure are largely de-

Dimensional properties of microfiber knits from open-end and ring spun yarns are being measured. F termined by the interdependence of each stitch with its neigh- IO - r bors on either side and above and below it. Knitted loops are e arranged in rows and columns roughly equivalent to the warp q and weft of woven structures termed ‘courses’ and ‘wales’ re- U spectively. The are determined in laboratory by using suit- e able magnifying and counting devices such as pick glass, rule n and pointer, microfilm reader or projection equipment. It C takes longer time and has lower accuracy. Variation in di- Y 0 mensional properties of weft knit fabric often results in differences in physical and mechanical properties such as heat # of cycles * 100 retention, permeability, tenacity, resilience, elasticity, abra- Frequency Dish-ibution of Warp Break on Loom sion resistance, fuzz resistance, pill resistance, snag. It is for Ring-spun Ywn

Narinnol Textile Center Quarterly Report: April - Jwte 1993 13 therefore desirable to have at our disposal accurate and effi- Today the term 1 cient methods for quantiQing aspects of dimensional mor- lTTFuT Or9 is known as the fabric “tightness factor” and d/L is known as phology of weft knit fabric. While dimensional the fabric “cover factor”. It was found that the linear dimen- morphometrics of weft knits been a rather manual affair, sions of the loop of the plain knit fabric in both conditions of there has not been any progress toward its automation. relaxation were given by the following equations: Measurements are generally limited to a few attributes, how- courses Kc ever, and there is a certain lack of consistency in the use of inch-r dimensional terminology. ~--wales _ Kw Computerized image capture and image analysis promise inch L rapid, accurate dimensional quantification of weft knit fabric. This report contains a number of dimensional descriptors of courses. wales7-- _ Kc . & = KS inch 111c11 L L i;r weft knit fabric that are intended to capture most of the variation in two dimensions. These descriptors have been put into courses/inch = J& JCr wales/inch Kw dimensional analysis program written in AL1 language of Where Kc, Kw, KS and Kr are constants could fabric dimensional parameters. OPTIMAS Image Analysis System. The algorithms we have used are also discussed. Image capture and processing are es- The following results were obtained from the experimental sential parts of this protocol, since some of the measurements observations on plain knit wool fabrics: we use are difficult or impractical to obtain by hand. I Dry Relaxed Wet Relaxed Description of Plain Knit Fabric Geometry 1 KS 19.2 21.6 Plain fabric is produced on a single set of needles with every 5 I 5.3 II loop pulled through the previous loop in the same direction. Kw 3.8 1 4.1 Thus on the technical back both the crown and base of the loop are visible with the Loop Shape of Knit FaLwic straight arms of the loop showing on the front. Three samples of single jersey fabric, they are made from A cross-sectional view three different OES spun yarns with the same yarn count. of the plain structure The only difference is that the diameter of micro-fiber is dif- shows that all the loops ferent. (See Table below) are bent into the third dimension due to the

Yarn manner in which the Diameter loops are pulled through Sl 25Nell OESYarn Spun 1 919 W 1 0.7 DPF each other. The structure is thus clearly un- 25 Nell OES Spun 40 A 1.0 DPF balanced causing the Yarn fabrics to curl at the 25Nell OES Spun 107w 1.5 DPF edges in an attempt to Yarn Loop release some of the strains within the loop. Width In order to make the testing data representable, twenty im- ages have been taken from each sample and for each index, Fabric Tightness and Quality fifty testing data were collected and mean value was given. It has already been shown that loop length is the only factor The undyed knitting fabrics are put on the blackboard, and influencing the dimensional properties of the knitted fabric. image is taken into video-recorder through CCD camera. However, yams of different counts knitted to the same loop length will display different physical properties, such as han- One macro program is designed especially to measure geome- dle, drape, openness, permeability, etc.. A fabric knitted try parameters of plain knit fabric, and is a semi-automatic from a course yarn will be much more tightly knitted for a operation. The testing data are automatically collected and given loop length than would a fine yarn. saved into a data file. It was suggested that numerical evaluation is described as Cover Factor = d/L, Tightness Factor = T**OS/ L wllsrs d=yam diamstsr, T=yarn count (kx), L=loop Irngtb “cover factor”. Thus the fractional area of space occupied by a knitted loop is given by: Loop length, loop width and loop height will describe the Area covered bv yarn in one loop --- 9 --- 1 -I-**0 5 shape of the loop. Course density, wale density and fabric Area of one loop L*N**O.S AL density are describtng the dimensional size of knit fabric.

where d=yam diameter, L=loop length, N=indirect count, T=dirsct count 14 The following three tables show the testing results:

Single Jersey of 0.7DPF, single jersey of l.ODPF, single jersey of l.SDPF have some differences in loop shape (such as loop length, loop width, loop height).

For the course density, wale density, and fabric density, single jersey of l.ODPF and single jersey of l.SDPF are similar, but single jersey of 0.7DPF has imported differences with them. When micro fiber diameter increases (0.7DPF --A l.ODPF ---> l.SDPF), yarn diameter decreases (0.0207cm --- s3 1 Yarn 1 Fabric 1 Cover 1 Tightness > 0.0194cm ---0.0191cm). Diameter Density Factor Factor Average 0.02 57.7 0.04 0.11 For the cover factor and tightness factor, single jersey of Value l.ODPF and single jersey of 1.5DPF are similar. Single jer- Standard 0 2.72 0.01 0.01 sey of 0.7DPF has some differences. Deviation CV (%) 13.51 4.72 14.43 5 N 150

*S3--- Single Jersey with micro fiber diameter 1.5PF; Magnification = 0.67 * 1.5 * 0.5; Measuring Unit = cm; Course Density = Courses / cm; Wale Density = Wales / cm;

Textile Structures for Composites s292c12 Principle Investigator And Reporter: Mansour Mohamed (NC State)

Objectives (Long Term): The overall objective of this work is to expand the boundaries of textile processing with the ultimate goal of producing new *s1 --- Single Jersey with micro fiber diameter 0.7DPF; multi-dimensional fibrous structures for composite Magnification = 0.67 * 1.5 * 0.5; Measuring Unit = cm; applications. Course Density = Courses / cm; Wale Density = Wales / cm; The application and development of textile preforms’ manufacturing methods by laminated and stitched fabrics, 2-D and 3-D braiding, 2-D and 3-D weaving, and warp and weft knitting. To produce composites from these complex textile structures using different infiltration and consolidation systems. To develop and validate analytical techniques for understanding the behavior of the composites as a func- tion of process and reinforcement structure. To develop a processing science and technology basis for the manufacturing of these materials and to develop an understanding of the interaction between processing performance. To develop a “performance map” of the different textile reinforcement structures in terms of mechanical properties, shape forming capabilities, and eventually, eco- s2 --- Single Jersey with micro fiber diameter 1 .ODPF; nomics to be used as a design guide for their Magnification = 0.67 * 1.5 * 0.5; Measuring Unit = cm; application in end use products. Course Density = Courses / cm; Wale Density = Wales / cm;

National Tatile Center Quarterly Report: April - June 1993 15