https://orcid.org/0000-0002-5766-7733
ABSTRACT
The physical and mechanical properties of German Angora rabbit fiber obtained from the Northeast region of India were studied. The fiber fineness, staple length, diameter, and medullation of the overall fleece of the rabbit were 0.22 ± 0.04 tex, 09.10 ± 2.21 cm, 23.5 ± 1.04 µm, and 85.46 ± 1.23%, respectively. The cross-sectional shape was found elliptical to oval, and the average tenacity, breaking elongation, specific work of rupture, and initial modulus were 24.78 ± 11.48 cN/tex, 28.78 ± 09.06%, 3.46 ± 2.31cN/tex, and 1065.13 ± 826.67 cN/tex, respectively. The whiteness index average ash and moisture content were 61.24 ± 2.32, 1.36 ± 0.12, and 10.43 ± 0.57%, respectively. Three blend ratios of Angora rabbit fiber and viscose fiber (50:50, 25:75, and 0:100) were used to make yarns having 55 tex, 86 tex, and 97 tex linear density from each blend. Tenacity and breaking elongation significantly (p = .00) increased with an increase in the rabbit fiber composition in the blend and was maximum at the 50:50 blend (7.79 ± 1.92 cN/tex and 7.64 ± 1.70%, respectively). Yarn diameter increased with the increase in yarn count. With the decrease in the rabbit fiber composition from 50% to 25% in the yarn, the friction coefficient increased and the abrasion resistance decreased significantly (p = .00).
摘要
对从印度东北地区获得的德国安哥拉兔纤维的物理力学性能进行了研究. 兔羊毛的纤维细度、纤维长度、直径和髓度分别为0.22 ± 0.04 tex、09.10 ± 2.21 cm、23.5 ± 1.04 µm和85.46 ± 1.23%. 横截面形状为椭圆形至椭圆形，平均韧性、断裂伸长率、断裂比功和初始模量分别为24.78 ± 11.48 cN/tex、28.78 ± 09.06%、3.46 ± 2.31cN/tex和1065.13 ± 826.67 cN/tex. 白度指数平均灰分和水分含量分别为61.24 ± 2.32、1.36 ± 0.12和10.43 ± 0.57%. 安哥拉兔纤维和粘胶纤维的三种共混比（50:50、25:75和0:100）用于由每种共混物制备具有55特、86特和97特线密度的纱线. 随着共混物中兔纤维成分的增加，韧性和断裂伸长率显著增加（p = .00），并且在50:50共混物时达到最大值（分别为7.79 ± 1.92 cN/tex和7.64 ± 1.70%）. 纱线直径随着纱线支数的增加而增加. 随着纱线中兔纤维成分从50%减少到25%，摩擦系数增加，耐磨性显著降低（p = .00）.
Introduction
Angora fiber is one of the luxury fine keratinous textile materials, produced by the long-haired Angora rabbit. Angora wool is soft, bright, fluffy, and light-weighted having excellent thermal insulation properties (Hunter Citation2020).
There are difficulties in spinning 100% Angora rabbit fiber due to its low cohesion force and short length. Researchers blended merino wool (Mishra and Goel Citation2004); Oglakcioglu et al. Citation2009); acrylic and wool (Süpüren Mengüç Citation2016; lyocell and cotton (Onal and Korkmaz Citation2006); nylon (Guruprasad and Chattopadhyay Citation2013) with Angora rabbit fiber to develop yarn and fabric. In most cases the selection of the fiber to be blended with Angora rabbit fiber is done by matching the fineness and thermal insulation properties. However, the selection of fiber should also be based on its ability to bind the short Angora fiber. Without thorough engineering considerations, the resulting yarn developed recorded a higher coefficient of variation in strength, thick-thin places, neps, hairiness, and abrasion properties. Better and uniform yarns are developed when blending of the fibers is done considering their engineering properties relevant to spinning. Herrmann, Wortmann, and Wortmann (Citation1996) studied the fiber and medulla diameter of the Angora rabbit fiber as affected by the origin of the rabbits. Rafat et al. (Citation2007) also analyzed important factors like fiber diameter, comfort factor, spinning fineness, fiber curvature, medulla content, and mean fiber diameter along the length of Angora rabbit fiber. However, a comprehensive analysis highlighting dimensional, tensile, and other properties relevant to spinning that would serve as a guide for selecting compatible fiber to make blended yarn was not focussed. Hence it was felt necessary to conduct a thorough study of the dimensional, chemical, and tensile properties of the down fiber and coarse hair so that it is easy to take decisions scientifically before making blended yarns.
Materials and methods
Materials
German Angora rabbit fiber
German Angora rabbit fiber was obtained from Namthang, South Sikkim, India. The rabbits were from a German breed grown up in Indian conditions. The age of the rabbits from which fiber was harvested was between 1.5 to 2 years and per rabbit 110 g fiber was obtained. Fiber from 30 rabbits was collected and sampling for evaluation was done by zoning techniques (Booth Citation1970).
Methods for measurement of fiber properties
Composition, length, and fineness
BIS standard IS 6359–1977 was used for the conditioning of fiber and was conditioned for 24 h at 27 ± 2°C at 65 ± 2% RH (relative humidity) before any test.
A random bunch of about 100 fibers was taken and the number of coarse hair and down fiber present in them was counted and expressed as a percentage by number. Ten replicates of the experiment were performed and the average percentage of coarse hair and fine fiber was reported. The hand stapling method was used to determine fiber length. About 30 coarse hairs and fine fiber each were separated from a random bunch of fiber. The selected fibers were laid one by one on a flat black background and the staple length was measured by a scale up to a precision of 0.5 mm. The average length of coarse hair and fine fiber was reported separately.
Similarly, the length of another set of approximately 100 randomly selected fiber containing both coarse hair and fine fiber was measured. The histogram and the average length, with standard deviation and coefficient of variation (CV), were reported. The fineness or linear density of coarse hair and fine fiber was determined separately by the gravimetric method using the following formula:
Linear density (tex) = W/L
Where, W is the weight of 10 randomly selected fiber measured on a digital weighing balance (Sartorius, AG-GOTTINGEN M2P) having the least count of 0.0001 mg and L represents the cumulative length of the same fibers. The experiment was repeated thrice. Similarly, the fineness of another set of approximately 100 randomly selected fiber containing both coarse hair and fine fiber was measured and the average fineness was reported.
Fiber crimp frequency of fine fiber
Crimp was observed in the fine fiber but the coarse hair was free from the crimp. Hundred fine fibers were randomly selected and laid parallel to a scale on a flat black background and the fiber crimp frequency was measured; expressed as the number of crimps per cm and presented in a histogram.
Diameter
Approximately a hundred fibers containing both fine fiber and coarse hair were randomly selected. The diameter of the selected fiber at three locations along the fiber length viz:1) root portion; (ii) mid-portion; (iii) apex portion was measured under the projection microscope (Nikon SMZ18). The histogram at each of the mentioned locations was presented on the histogram. The average diameter was estimated based on the readings from all three locations.
A separate bunch of about 30 coarse hairs and fine fiber each was separated from a random bunch of fibers. The diameter at the mid-portion of the hair shaft was measured by the procedure mentioned above and the average diameter of coarse hair and fine fiber was reported.
Tensile properties
Tensile properties for randomly selected hundred fibers containing both fine fiber and coarse hair were tested on the tensile tester (Instron, 5567) following Indian standards (BIS 235; 1991). The fiber is subjected to a load that increases at a constant rate such that the average time to break falls within the specified limit of 20 ± 3 s. The gauge length was kept at 2 cm. The average tenacity, breaking elongation (%), specific work of rupture, and initial modulus were reported on the histogram.
The test was repeated for 30 coarse hairs and fine fiber each derived randomly from the fiber and the average values of the tensile properties for coarse hair and fine fiber were also reported.
Whiteness index and dye uptake
The Whiteness index of a randomly selected about 100 g of fiber was measured using a spectrometer (Premier Colorscan, SS6200). Acid dying of fiber was carried out using Acid red dye 131, cash No. 12234–9900. About 5 g of fiber was taken for dye application and 2% dye on fiber weight was used. The fiber was boiled in the dye solution at 100°C for 1.5 hours. The concentration of dye in the solution before and after dyeing was measured using a spectrophotometer (LABINDIA UV 3092, UV-VIS Spectrophotometer). The concentration difference was used to measure the dye exhaustion.
The cross-sectional shape and medullation percentage
A scanning electron microscope (Philips XL − 30 SEM, The Netherlands) was used for studying the cross-section fiber. Images were taken at the mid-portion of a random bunch of fibers consisting of both fine fiber and coarse hair. The cross-sectional shapes and medullation percentage were determined from the images. The ImajeJ software was used to determine the ellipticity of the fibers.
Fiber moisture, grease, and ash-content
About one gram of fiber is dried in a ventilated oven till constant weight is achieved. The difference in weight before and after drying determines the amount of moisture present in the fiber. Moisture content was expressed as a percentage of the initial weight of the fiber. Three replicates of the experiment were done. The grease/fat content of the fiber was determined following ASTM D2257 standard using a Soxhlet apparatus using benzene s the solvent. The experiment was carried out in three replicates and the average fat content in % was reported. The ash content was determined following ASTME1755–01 (2003) standard method.
Yarn construction
Manually opening and blending of two fibers were done. Three blend ratios were made varying the proportion of fiber and Viscose fiber in the blend (50:50, 25:75, 0:100). Carding was done twice in a full circular roller and clearer type flax card. To obtain a uniform sliver three drawing frame of the jute system was used. In the first drawing single passage was used. Two times the fibers were passed through the second drawing system and a single passage has been used in the third drawing system. All the drawings were jute gill drawings. Mackie Apron draft Jute spinning Machine has been used to produce a very fine yarn. The spinning is made at 3000 rpm spindle speed with 8.31 twists per inch. From each blend ratio yarn having 55 tex, 86 tex, and 97 tex linear density was produced. A total of nine yarns were developed and their physical properties were measured.
Evaluation of yarn properties
Tensile properties were measured using a Universal tensile tester (Instron, 5567) following Indian standards (BIS: 235: 1989). The yarn is subjected to a load that increased at a constant rate such that the average time to break falls within the specified limit of 20 ± 3 s keeping a gauge length of 500 mm. The average tenacity, breaking elongation (%), specific work of rupture, and initial modulus of twenty-five replicates of each of the nine yarns were measured and the average value with standard deviation was reported.
Measurement of the diameter of the yarns was accomplished by projecting the magnified image (30 ×) of the yarn on a calibrated screen using a microscope (Projectina CH-9435, Heerbrugg, Switzerland). The average and standard deviation of fifty readings were reported.
The flexural rigidity of each of the nine yarns was evaluated by making a yarn ring of about 3 ± 0.5 cm in diameter. The flexural rigidity data was divided by the yarn’s linear density to obtain specific flexural rigidity. Thirty replicates of each yarn sample were analyzed and the average value with standard deviation was reported.
The yarn-to-metal friction was measured using a friction tester with the inclined plane principle (Debnath, Sengupta, and Singh Citation2007). Thirty replicates of each yarn sample were analyzed and the average value with standard deviation was reported.
Hairiness was measured manually (Debnath, Sengupta, and Singh Citation2007). Thirty yarn specimens of 25 cm each in length were prepared from each of the nine yarn samples. Each specimen was placed on a microscope (Projectina CH-9435, Heerbrugg, Switzerland) having a magnification of 30× and an aperture size of 5.3 cm. The number of hair longer than three mm which was projected on an axis perpendicular to the yarn axis was counted and used to express hairiness as the number of hairs/m yarn. After each reading, the yarn specimen was moved horizontally by 2 cm and the next reading on the same specimen sample was taken. The average of all the readings for each yarn was reported with the standard deviation.
The abrasion resistance of the yarns was measured using an abrasion resistance tester (SITRA ABRATEST). A water emery sheet number 320 was cut to a specified dimension and was fixed over the abrasion roller. Twenty specimens of each yarn were cut to a length of about 50 cm. One end of the yarn was tied to a stationary holding bar on the top of the instrument and the other is tied to a pretension weight of about 30 g. The sheet of parallel yarn was subjected to abrasion over an abrasive roller under the specified condition of tension and pressure. As the roller traverse back and forth the computer keep a track of the number of strokes made by the abrasive roller to rupture the yarn sample. The average number of cycles required abrading the yarn fully and the standard deviation was reported for each yarn.
Statistical Analysis
All the mean, standard deviation, and coefficient of variation (CV) were estimated using Microsoft Excel, 2010. The same software was used to also draw the histograms. The effect of the different blend ratios, yarn count, and their interaction effect on the yarn tensile properties, diameter, yarn density, coefficient of friction, no. of cycles to abrasion, specific flexural rigidity, and hairiness was done by two-way analysis of variance (ANOVA) technique. One-way ANOVA was used to study the effect of each of the two factors (viz. blend ratio and yarn count) on the responses. The SPSS 20 software was used for all the analyses.
Results and discussion
Fiber composition and physical properties
The composition of coarse hair was approximately 2.5%. Fine fiber constituted 97.5% of the remaining population. Perincek et al. (Citation2008) have reported that coarse hair ranges between 1–3% of the total hair in German Angora rabbit fiber. The fineness of the fine fiber and coarse hair were reported in . The average fineness was similar to the fineness value (0.22 tex) reported by Lakshmanan, Jose, and Chakraborty (Citation2016) for fiber of Indian origin; and Menguc, Ozdil, and Kayseri (Citation2014) (0.35 tex) for fiber from china. Hunter (Citation2020) stated that the average fineness value of six genetic groups of rabbit fiber ranged between 0.14–0.23.
Table 1. Physical properties of coarse hair, and fine fiber.
The coarse hairs were longer than the fine fiber (08.9 ± 01.6) (). shows the length distribution of fiber. The highest frequency of about 25% was observed in the class range of 91–100 mm. Fibers are graded based on their length in different counties United States of America and the German system. Based on the fiber length following four grades of white, clean, and tangles free fiber were described by Muthu and Eds. Gardetti (Citation2016): i) grade one is 5.0–7.6 cm long; ii) grade two is 3.8–5.0 cm long; iii) grade three is 2.5–3.8 cm long, and iv) grade four is any length.
Figure 1. Length distribution of fiber.
shows the fiber crimp frequency in the fine fiber. About 90% of the fiber had 2–4 crimps per cm. The average fiber crimp frequency was 2.9 ± 0.6, CV = 21%. Hunter (Citation2020) classified Angora rabbit fiber as a fiber having very low fiber crimp frequency (2.7 crimp/cm) compared to wool (5.5 crimp/cm) which is classified as having good crimp.
Figure 2. Fiber crimp frequency distribution of fine fiber.
The study of the microscopic characteristics of animal fiber such as cortical cuticular and medullary patterns, the type of cuticular scales covering the cortex, and their pattern of arrangement concerning the longitudinal axis of the fiber gives important insight. shows the cross-sectional view of fiber. From the figure it was estimated that the cross-sectional shape of about 50% of the cells was elliptical, approximately 20% were oval and the remaining cells were rectangular shape (approximately 14%), dumbbell-shape (approximately 14%), and circular shape (approximately 04%).
Figure 3. (a) Cross-sectional view of fiber showing: a) dumble shape; (b) oval shape; (c) circular shape; (d) elleptical shape; and (e) rectangular shaped cells. (b) Cross-sectional view of fiber showing: 1) no medulla; (2) square shape single medulla; (3) elliptical shaped single medulla; (4) multiple medulla.
McGregor (Citation2018) stated that animal fibers are mostly elliptical in cross-section and the ellipticity (the ratio between the major and minor cross-sectional diameters of fiber) is an important factor determining spinning performance. Figure 4.3(b) shows the major and minor cross-sectional axis of the Angora rabbit fiber. The average ellipticity of the elliptical and the dumb-bell-shaped fiber was 2.7 ± 1.2, CV = 54.6. The value is lower than that stated by Hunter (Citation2020) for Angora rabbit fiber (ellipticity = 4) but is greater than that observed in cashmere (ellipticity = 1.2), alpaca (ellipticity = 1.3–1.3). The higher ellipticity values in Angora rabbit fiber are attributed to the presence of medullated fiber. A reduction in the bending rigidity and an increased softness are observed in animal fibers having higher ellipticity values (McGregor Citation2018).
shows that most of the cross-sections had one large medulla, few were without a medulla and very few cross-sections have two or more medullas. Van den Broeck, Mortier, and Simoens (Citation2001) stated that the multi-serial ladder medulla is present in the coarse hair and the uniserial ladder-type medulla is present in the fine fiber. The percentage of medullated fiber was 85.4 ± 1.2%, CV = 1.4%. Percentage medullation is lower than that observed in French Angora fiber (99.9%), German (90.5%), and Chinese (96.8%).
The shape of the medullary channels was not uniformly circular. Square, triangular, and elliptical shaped medullary canals were also observed. Hence their dimension is not expressed as the ratio of medulla diameter to cell diameter. Medullar cell cross-section area relative to the cell cross-sectional area would provide a better insight. It was observed that 3.98 ± 2.34% of the cell cross-sectional area was medullated. The medulla is responsible for lower bulk density and higher thermal insulation properties of the Angora rabbit fiber. However, the presence of the medulla also significantly reduces the strength, and flexibility of the fibers (Zheng et al. Citation2011).
Medullation properties are important to determine the dyeing ability of the fiber because higher medullation causes greater refraction of light at the fiber/medulla interface and the decreased length of the light path within air-filled medulla cells (Hunter Citation2020). Onal and Korkmaz (Citation2006)reported 36.7% as the average medullation by volume for French Angora rabbits.
Fiber diameter
The diameter of a fiber is the distance across its cross-section. The diameter of natural fiber usually varies over its length, so the diameter distribution at the root, mid-portion, and apex positions of fiber shaft is presented in . In the root portion, about 95% of the fiber had a diameter between 20–30 µm, in the middle portion of the fiber shaft, about 80% of the fiber is in that range. The remaining 20% was having a lesser diameter which ranged from 10–15 µm. In the apex region, 95% of fiber was between 10–20 µm and a small fraction was having a diameter between 0–10 µm. The average diameter was 19.94 ± 5.1 µm, CV = 25.6%. Herrmann, Wortmann, and Wortmann (Citation1996) stated that the quality of fiber varies between counties and the diameter of fiber of French origin (19.8 µm) was comparable with our results. But it is higher than the diameter of fiber of German origin (12.4 µm) and Chinese origin (11.8 µm).
Figure 4. Diameter distribution at the root, middle and apex portion of fiber.
Fiber tensile properties
The study of the tensile properties of fiber is important because fiber is subjected to forces along the longitudinal and transverse directions during spinning and post-spinning operations. The behavior of the fiber to the applied force influences yarn properties like Young’s modulus, bending stiffness, torsional rigidity, and fabric properties like drape, wrinkle recovery, etc. (Varshney, Kothari, and Dhamija Citation2011). The tenacity of about 45% fiber was 20 cN/tex, remaining 45% fiber had tenacity values between 30–50 cN/tex (). The difference in the fiber tenacity can generally be attributed to factors like the crystallinity, degree of polymerization, the forces holding the adjacent polymer chains together, and their degree of orientation in the direction of fiber axis. The average tenacity was 24.7 ± 11.4, CV = 46.31%.
Figure 5. (a). Frequency distribution of the tenacity of fiber. (b) Frequency distribution of the breaking elongation of fiber. (c) Frequency distribution of the specific work of rupture of fiber. (d) Frequency distribution of the Initial modulus of fiber.
Elmogahzy and Farag (Citation2018) explained that fiber elongation reflects how easily the fiber can be stretched. It is difficult to stretch fiber with low breaking elongation concerning high breaking strength values. About 80% of the Angora rabbit fiber had a breaking elongation between 20–40% ().
The toughness of a fiber is reflected by the energy required to break and is known as the work of rupture. About 90% of the fiber has the specific work of rupture between 2.5–7.5 cN/tex (). The average specific work of rupture was 3.4 ± 2.3, CV = 67%. The value is greater than that of the cotton fiber (0.5–1.5 cN/tex) and is comparable with wool fibers (2.7 to 3.8 cN/tex) (Elmogahzy and Farag Citation2018). The initial modulus or the elastic modulus reflects the stress require to double the length of the fiber following Hook’s law (Morton and Hearle Citation1975). About 45% of the fiber has an initial modulus value of about 1000 cN/tex, approximately 35% has a value of about 2000 cN/tex and the remaining 20% of fiber had initial modulus values between 2000–4000 cN/tex (). The average initial modulus was 1065.1 ± 826.7, CV = 77.6%.
Grease content, moisture content, and ash content
The average grease in fiber was 4 ± 0.7%. The observed value is higher than that stated by Hunter (Citation2020)The authors mentioned that Angora rabbit hair contains 1% of natural grease and they don’t need scouring before processing. These lipid materials are mainly composed of cholesterol, fatty acids, and polar lipids and originate from all kinds of membranes surrounding living cells.
The average moisture content of fiber was 10.4 ± 0.6%. Many physical properties of fiber are affected by the amount of water absorbed, e.g. dimensions, tensile strength, elastic recovery, electric resistance, rigidity, and so on. showed that it takes about five days to regain the moisture from the bone-dry state of fiber to about 9.1 ± 0. 5 Ash is the inorganic residue remaining after the water and organic matter have been removed by heating in the presence of oxidizing agents, which provides a measure of the total amount of minerals. The average ash content was 1.4 ± 0.1. Hunter (Citation2020) stated that the mineral salts, nucleic acid residues, and carbohydrates content of wool is about one % and the content of mineral salts is partially nutrition dependent
Figure 6. Moisture regain-time curve of Angora rabbit fiber.
Fiber whiteness index and dye exhaustion
The values of the whiteness index were 61.2 ± 2.3 and are comparable with the whiteness index of cotton fiber bleached with hydrogen peroxide (56–59) (Haque et al. Citation2018). Whiteness is an aspect of color resulting from high luminosity with an absence of any hue. It is a desirable property of fiber. The dye exhaustion was 60%. Dye exhaustion gives insight into the relative dyeing kinetic when different fibers composing a yarn compete in a dyeing medium.
yarns having the highest proportion of Angora rabbit fiber (50%) showed the maximum tenacity and breaking elongation values at all levels of yarn count (55 tex, 86 tex, and 97 tex).
Table 2. The effect of the change in Angora rabbit fiber composition in the blend and change in yarn count on the tensile properties of the Angora-Viscose yarn.
The ANOVA results showed that increasing the proportion of Angora rabbit fiber in the blend significantly (p = .000) increased the tenacity of the Angora viscose blended yarn. Greater strength and elongation are found when the yarn is made from fiber having higher tenacity and elongation values (Tesema and Drieling, Citation2020). Angora rabbit fiber has higher tenacity values because they are extremely fine and its elongation values also were higher. Significantly higher tenacity was observed in 100% viscose yarn at all levels of yarn count compared to 25:75 yarn. The tenacity of viscose fiber (25cN/tex) was comparable with Angora rabbit fiber (24.8 ± 11.5 cN/tex) but bonding between the fiber and the corresponding yarn strength was strongest when similar fiber surfaces were twisted into yarn compared to when two different fiber surfaces (Angora fiber and viscose fiber) are twisted into yarn in 25:75 blend. Yarn count was not significant (p = .586) on the tenacity but the interaction effect of the blend ratio and the yarn count was found to have a significant effect (p = .000). The finest yarn from the 50:50 blend had the highest tenacity value (7.8 ± 1.9 cN/tex). The specific work of rupture value was highest at 55 tex in a 50:50 blend. It was obviously due to the high tenacity and elongation of the corresponding yarn. Changes in the specific work of rupture followed a similar trend as changes in the tenacity values for all the yarn counts and it increased significantly (p = .00) with the increase in the proportion of Angora rabbit fiber in the blend. The yarn count had no significant effect (p = .99) however, the interaction effect of the blend ratio and the yarn count showed significant (p = .000) on the specific work of rupture.
A change in the proportion of Angora rabbit fiber in the blend had a no-significant effect (p = .74) on the change in the initial modulus value. The yarn stiffness decreases significantly with the increase in yarn count from 55 tex to 86 tex in the 50:50 and 25:75 blend (). However, in the same blends when the yarn count increased to 97 tex the further change in the initial modulus value was non-significant. In 100% viscose yarn the effect of the increase in yarn count was non-significant on the initial modulus value. Hence it may be inferred that when Angora rabbit fiber was present in the blend, the thinner yarn was stiffer than the thicker yarn and they offered greater resistance to deformation under small forces and hence had better shock absorption capabilities than thicker yarn. The interaction effect of the blend ratio and the yarn count was also significant (p = .000) on the initial modulus value.
Table 3. The effect of the change in Angora rabbit fiber composition in the blend and change in yarn count on the diameter, density and surface properties of the Angora-Viscose yarn.
showed that with a decrease in the yarn count from 97 tex to 86 tex and then to 55 tex the diameter of the Angora -Viscose blended yarn decreased significantly (p = .00) at each of the three blend ratios (50:50, 25:75, 0:100). It may be because the number of fiber inside the yarn cross-section decreased with decreasing the value of yarn count (Zou Citation2014).
When the blend ratio changed to 25:75 and 0:100, the average flexural rigidity increased from 2160.9 ± 608.3 × 10−4 to 2355.6 ± 569.3 × 10−4 mN.mm2/tex and 2505.9 ± 326.7 × 10−4 mN.mm2/tex, respectively non-significantly (p = .24). Therefore the yarn from the blend having a higher proportion of Angora rabbit fiber (50:50) is expected to have lower flexural rigidity values than yarn from the blend having 100% viscose fiber and 0% Angora rabbit fiber (0:100). The specific flexural rigidity of viscose fiber was relatively higher (0.4–0.7 mN mm2/tex2) than fine fiber (0.2 mN mm2/tex2) (Morton and Hearle Citation1975). The interaction effect of the blend ratio and the yarn count was significant (p = .000). It indicated that only at higher yarn count it was significantly difficult to bend the yarn when the proportion of Angora rabbit fiber in the blend decreased.
The decrease in resistance to abrasion with reducing the proportion of Angora rabbit fiber in the yarn can be attributed to the relatively lower co-efficient of metal-to-fiber friction of Angora rabbit fiber (0.2–0.3) (Hunter Citation2020) compared to viscose fiber (0.35–0.40) (Das and Ishtiaque Citation2007). The average hairiness of the yarns showed no significant (p = .33) change with the change in Angora rabbit composition in the yarn. The fiber end of rigid fiber would protrude and become a hair because they offer greater resistance to bend in the yarn compared to flexible fiber. Since viscose fiber was comparatively more rigid than Angora fiber. The yarn from 100% viscose also showed higher hairiness value and there was no significant difference when compared to the yarn containing 25% or 50% Angora rabbit fiber.
Conclusions
Physical properties like length, diameter, crimp, tensile properties, cross-sectional shape, etc., are important for finding a blend compatibility point of view. After evaluating the properties viscose fiber was found best compatible to blend with Angora fiber. Nine different yarns were developed from three blends of Angora rabbit and viscose fiber having three different linear densities. The 55-tex yarn from the 50:50 blend showed the highest tenacity (7.8 ± 2.0 cN/tex), breaking elongation (7.64 ± 1.7%), and co-efficient of friction (0.5 ± 0.1) and the lowest specific flexural rigidity. Costefficient fine yarn can be made from Angora viscose blend having promising tensile and frictional properties suitable for the fashion industry.
Highlights
German Angora rabbit fiber of Indian origin was evaluated
Based on the properties viscose fiber was blended to develop yarn
The 55 tex yarn from 50:50 Angora fiber : Viscose blend showed best properties.
The yarn reported promising tensile and frictional properties
Cost-efficient fine yarn suitable for fashion industry can be made from Angora viscose blend
Author’s contribution
SANCHITA BISWAS MURMU: Planning and conducting experiments, Analysis of data, writing research paper.
SANJOY DEBNATH: Planning and execution.
Chewang N. Bhutia: Experiments conducting.
Ethical approval
This work does not involve requirement of ethical approval.
Acknowledgements
The author is thankful to the Director, ICAR-NINFET for supporting this research work.
Disclosure statement
No potential conflict of interest was reported by the authors.
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