q1nonwoven
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Q1: Define nonwovens as per ASTM. Q2: Define nonwovens as given by INDA. Q3: How would you characterize fibre packing arrangement in nonwovens? Q4: Which of the following four structures is best suited for nonwovens: tightest
structure, tight structure, intermediate structure, and loose structure? Q5: What is the value of probability density function of isotropic fibre orientation? Q6: What is the relation between porosity and pore size? FAQs are also available in Download section Q1: Which of the following opener you would prefer to use for processing of bleached
cotton: universal opener, single roll opener, and multi roll opener? Q2: How would you characterize the performance of an opener? Q3: Name three web weight control systems used in manufacturing of nonwoven webs.
Which of them can control longitudinal as well as transverse weight uniformity? Q4: How would you characterize the performance of roller carding process? Q5: How would you expect to increase the collection power of worker in roller carding
process? Q6: State the significance of double doffer system Q7: Name the three types of web stacking process. Which of them is mostly preferred
for continuous production of multilayered webs where each layer consists of different types of fibres?
Q8: Which of the web stacking processes is mostly preferred for production of highloft nonwovens?
Q9: Which of the web stacking processes is mostly preferred for obtaining significant z-directional orientation of fibres in the webs?
Q10: Which technology would you prefer to use for obtaining isotropic fibre orientation distribution: carding or air-lay?
Q11: Why it is necessary to disperse the fibres in water? FAQs are also available in Download section Q1: Name two mechanical bonding processes. Q2: Which type of needle do you prefer for processing of shoddy and waste fibres and
why? . Q3: Which of the follows barbs shows the highest fibre carrying capacity: K barb, NK
barb, and B barb? Q4: Which of the follows barbs provides maximum aggressive punching: regular barb,
medium barb, close barb, and high density barb? Q5: Q3: Which of the follows barb angles result in the highest fibre carrying capacity: 5
degree, 10 degree, and 15 degree? Q6: When the star bladed needles are preferred over the standard triangular needle? Q7: Is it so that the coarser gauge needles are required for processing of coarser fibres? Q8: Why viscose fibres are found to be easily hydroentangled than polypropylene fibres? Q9: Which of the following three nozzles has the highest discharge coefficient: cone-up
nozzle, cone-down nozzle, and cylindrical nozzle? Q10: Which of the following three nozzles results in the lowest break up length: cone-
up nozzle, cone-down nozzle, and cylindrical nozzle? Q11: What is the dominant mode of heat transfer in thermal calender bonding? Q12: Which of the bonding methods would you prefer to prepare softer fabric: point
bonding or area bonding? Q13: Is it so that the velocity of the thermal calender rollers need to be higher while
preparaing light weight fabric as compared to heavy weight fabric? Q14: Which of the bonding processes would you prefer for development of highloft
nonwovens? Q15: What is the dominant mode of heat transfer in through-air thermal bonding? Q16: What is the dominant mode of heat transfer in infrared bonding? Q17: What are chemical binders?
Q18: Describe how fibre bonding takes place in chemical bonding? Q19: What are the methods of binder application for chemical bonding of nonwovens? FAQs are also available in Download section Q1: State the role polymer throughput rate on the development of morphology and
diameter of the filaments in spunbonding process. Q2: State the sequence of meltblown process. Q3: Discuss the role of die to collector distance on the quality of meltblown nonwoven. FAQs are also available in Download section Q1: What is splitting? Q2: What is the role of compressive finishing? Q3: What is shearing? Q4: What is flocking? Q5: What is raising? Q6: What is the difference between raising and sueding? Q7: What are the ways of applying chemical finishes to nonwoven fabrics?
Q1: Define nonwovens as per ASTM.Ans.1: As per ASTM, nonwoven is defined as a textile structure produced by bonding or interlocking of fibers, or both, accomplished by mechanical, chemical, thermal, or solvent means, and combinations thereof. Note: the term does not include paper, or fabrics which are woven, knitted, tufted, or those made by wool or other felting processes.
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Q2: Define nonwovens as given by INDA.Ans.2: According to INDA, Nonwoven fabrics are broadly defined as sheet or web structures bonded together by entangling fiber or filaments (and by perforating films) mechanically, thermally or chemically. They are flat, porous sheets that are made directly from separate fibers or from molten plastic or plastic film. They are not made by weaving or knitting and do not require converting the fibers to yarn.
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Q3: How would you characterize fibre packing arrangement in nonwovens?Ans.3: The fibre packing arrangement in nonwovens can be characterized by fibre packing density.
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Q4: Which of the following four structures is best suited for nonwovens: tightest structure, tight structure, intermediate structure, and loose structure?Ans.8: Loose structure.
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Q5: What is the value of probability density function of isotropic fibre orientation?Ans.9: 0.3185
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Q6: What is the relation between porosity and pore size?Ans.6: The pore diameter is inversely proportional to the supplement of porosity (one minus porosity).
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Q1: Which of the following opener you would prefer to use for processing of bleached cotton: universal opener, single roll opener, and multi roll opener?Ans.1: Multiroll opener.
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Q2: How would you characterize the performance of an opener?Ans.2: The performance of an opener is generally characterized by intensity of opening.
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Q3: Name three web weight control systems used in manufacturing of nonwoven webs. Which of them can control longitudinal as well as transverse weight uniformity?Ans.3: Weighing pan system, roller weighing system, and scanfeed system. Out of them, scanfeed system is known to control longitudinal as well as transverse weight uniformity
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Q4: How would you characterize the performance of roller carding process?Ans.4: The performance of roller carding process is generally characterized by intensity of carding and delay factor.
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Q5: How would you expect to increase the collection power of worker in roller carding process?Ans.5: The collection power of worker can be increased by increasing worker speed and keeping closer worker-cylinder distance. Also, use of a fancy roller in-between worker and clearer enables easy fibre transfer from worker to clearer.
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Q6: State the significance of double doffer systemAns.6: The double doffer system tends to increase fiber transfer from cylinder to doffers, thereby increase production.
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Q7: Name the three types of web stacking process. Which of them is mostly preferred for continuous production of multilayered webs where each layer consists of different types of fibres?Ans.7: The three web stacking processes are parallel-lay process, cross-lay process, and perpendicular-lay process. Out of them, the parallel-lay process is mostly preferred for continuous production of multilayered webs where each layer consists of different types of fibres.
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Q8: Which of the web stacking processes is mostly preferred for production of highloft nonwovens?Ans.9: Cross-lay process
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Q9: Which of the web stacking processes is mostly preferred for obtaining significant z-directional orientation of fibres in the webs?Ans.9: Perpendicular-lay process.
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Q10: Which technology would you prefer to use for obtaining isotropic fibre orientation distribution: carding or air-lay?Ans.10: Air-lay technology.
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Q11: Why it is necessary to disperse the fibres in water?Ans.11: It is necessary to disperse the fibres in water because of 1) to utilize short fibres for making webs, 2) to prepare webs with nearly isotropic fibre orientation, and 3) to process fibres with relatively high bending rigidity, for example, glass fibre.
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Q1: Name two mechanical bonding processes.Ans.1: Needle punching process and hydroentanglement process
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Q2: Which type of needle do you prefer for processing of shoddy and waste fibres and why? .Ans.2: The single reduction needle is preferred for processing of shoddy and waste fibres, because it is much stiffer than the double reduction needle
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Q3: Which of the follows barbs shows the highest fibre carrying capacity: K barb, NK barb, and B barb?A3: K barb.
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Q4: Which of the follows barbs provides maximum aggressive punching: regular barb, medium barb, close barb, and high density barb?Ans.4: High density barb.
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Q5: Q3: Which of the follows barb angles result in the highest fibre carrying capacity: 5 degree, 10 degree, and 15 degree?Ans.5: 15 degree.
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Q6: When the star bladed needles are preferred over the standard triangular needle?Ans.6: The star bladed needles are intended to carry an increased number of fibres per penetration as compared to the standard triangular needle and this results in higher fabric strength.
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Q7: Is it so that the coarser gauge needles are required for processing of coarser fibres?Ans.7: Yes
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Q8: Why viscose fibres are found to be easily hydroentangled than polypropylene fibres?A8: Viscose rayon has a low wet modulus and this partly explains the ease with which this fibre can be hydroentangled as compared to polypropylene fibres that have higher modulus.
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Q9: Which of the following three nozzles has the highest discharge coefficient: cone-up nozzle, cone-down nozzle, and cylindrical nozzle?Ans.9: Cone-up nozzle.
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Q10: Which of the following three nozzles results in the lowest break up length: cone-up nozzle, cone-down nozzle, and cylindrical nozzle?Ans.10: Cone-up nozzle.
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Q11: What is the dominant mode of heat transfer in thermal calender bonding?Ans.11: Conduction.
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Q12: Which of the bonding methods would you prefer to prepare softer fabric: point bonding or area bonding?Ans.12: Point bonding.
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Q13: Is it so that the velocity of the thermal calender rollers need to be higher while preparaing light weight fabric as compared to heavy weight fabric?Ans.13: Yes
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Q14: Which of the bonding processes would you prefer for development of highloft nonwovens?Ans.14: Through-air bonding
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Q15: What is the dominant mode of heat transfer in through-air thermal bonding?A15: Convection.
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Q16: What is the dominant mode of heat transfer in infrared bonding?Ans.16: Radiation.
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Q17: What are chemical binders?Ans.17: Chemical binders are polymers that are formed by emulsion polymerization.
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Q18: Describe how fibre bonding takes place in chemical bonding?Ans.18: The chemical binders are applied to nonwovens and as their viscosity is close to that of water they can easily penetrate into nonwoven structure by emulsion. After application of binder by, for example, immersion, they are dried and the water evaporates. The binder then forms an adhesive film across or between fibre intersections and fibre bonding takes place.
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Q19: What are the methods of binder application for chemical bonding of nonwovens?Ans.19: The methods of binder application for chemical bonding of nonwovens are saturation bonding, foam bonding, spray bonding, and print bonding.
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Q1: State the role polymer throughput rate on the development of morphology and diameter of the filaments in spunbonding process.Ans.1: The polymer throughput rate determines the morphology and diameter of the filaments. The morphology of the filaments spun at lower throughput rate is better developed than those at higher throughput rate. Because the rhelogical conditions are more favorable for crystallinity and orientation of the filaments spun at lower throughput rate. The filaments spun at lower throughput rate are thus more stable than those spun at higher throughput rate. The filament diameter increases with increasing throughput rate.
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Q2: State the sequence of meltblown process.Ans.2: The sequence of meltblown process is as follows: (i) preparation of polymers for extrusion, (ii) extrusion of low viscosity polymer melt through fine capillaries, (iii) blowing high velocity hot air to the molten polymer and attenuate the polymer melt, (iv) cooling the molten polymer by turbulent ambient air to form fine fiber, and (v) depositing the fibers onto a collecting device to form useful articles like fabric.
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Q3: Discuss the role of die to collector distance on the quality of meltblown nonwoven.Ans.3: The die to collector distance plays an important role on the quality of meltblown nonwoven. The higher distance results in higher fiber entangling, bulkier and softer web, better fiber cooling, less tendency to disturb fiber lay down, less web uniformity, and is used for heavy basis weight fabric (sorbent products, etc.). The lower distance results in less fiber entangling, more compact/stiffer web, balance of process air and suction capability, more uniformed web with better barrier properties, and is used for light basis weight fabric, especially light weight spunmelt composites.
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Q1: What is splitting?Ans.1: Splitting is a mechanical finishing process for preparation of nonwoven fabric. The process of separating one high basis weight and high thickness nonwoven fabric into two fabrics of high basis weight and lower thickness is known as splitting.
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Q2: What is the role of compressive finishing?Ans.2: Sometimes nonwoven fabrics are required to have papery like feel, hence lacking in handle and drape properties. Such properties when demanded by the consumers are deliberately introduced in the fabric to give the material more volume and softness. This process is carried out by the mechanical finish process known as compressive finish.
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Q3: What is shearing?Ans.3: Shearing is a mechanical finishing process of removing surface fibres from the fabric by the help of cropping or cutting. It is an alternative to singeing process. Unlike singeing, only partial surface fibre removal is achieved as the variation in fabric surface topography determines the cutting height.
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Q4: What is flocking?Ans.4: Flocking is a mechanical finishing process of producing three dimensional piles on the surface of a nonwoven backing fabric.
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Q5: What is raising?Ans.5: Raising is a mechanical finishing process to create fibrous pile structures on the surface of a pre-formed fabric.
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Q6: What is the difference between raising and sueding?Ans.6: In sueding, fabric surface is abraded by emerising fillet, but in raising it is done by raising wire.
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Q7: What are the ways of applying chemical finishes to nonwoven fabrics?Ans.7: There are several conventional and nonconventional ways to apply chemical finishes to nonwoven fabrics. The conventional ways include dyeing, printing, padding, coating, and lamination. The nonconventional ways include ultrasonic welding, plasma, and microencapsulation.