This article knitting fair explains the application of reduced graphene oxide on cotton woven fabric to achieve breathable waterproof finishing. After finishing the fabric was analysed various morphological properties as well as physical properties to confirm comfortability.
The spray test determines the water resistance of the treated and untreated fabrics by using AATCC 22 (1996) test method. In fig 6 showed standard spray test ratings.
Spray test ratings displayed in Fig. 7. In 80 – 20 ratio treated sample was achieved better water resistance rating about 90, as compared to 50 -50 and 60 – 40 ratio treated samples. In 80 – 20 ratio coated sample, water droplets can be seen on the fabric surface which indicated waterproof property (Fig 8a) and untreated fabric sample was completely wet on both surfaces (Fig 8b).
According to the spray rating chart, 80-20 ratio of rGO/PUA sample achieved the highest rating of 90 and this rating implies that there was “slight random sticking or wetting of upper surface”. It was observed that amongst these three samples, the sample from 80% rGO and 20% PUA showed maximum resistance to water and very slight wetting of the surface. It can be noted that as the amount of PUA was lowered, the water resistance was increased.
The tensile strength test is performed to evaluate the mechanical properties of the fabric. During the coating process, the fabric might undergo changes in its physical properties due to tension and stretching. Sometimes the tensile strength of the fabric might get reduced due to the coating process. Hence this test ensures that no undesirable change has occurred in the strength of the fabric due to the coating process. The tensile strength was performed in both the directions: warp and weft.
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From the above results, it was observed that the tensile strength increased in both directions after the coating was applied. The maximum increase in average tensile strength in warp and weft direction was seen in the sample with 80-20 rGO/PUV composition. As the coat was applied using PUA which also worked as a binder imparted in the tensile strength of the fabric.
While with reducing the concentration of PUA the strength increased this may be because of the rGO particles which are known to have higher mechanical strength. As the concentration of rGO increased it improved the strength of the coat indirectly resulting in higher tensile strength.
The rGO particles may have acted as particle reinforcement in the PUA whilst directly improving the tensile characteristics of the PUA, which can be seen in the results obtained.
The thickness test was performed to evaluate whether an application of coating added undesirable thickness to the fabric.
In the case of untreated fabric, the average thickness was calculated as 287µm. The sample composed of 50% GO and 50% PUA has the lowest average thickness, equaling 313.5µm. Furthermore, the highest thickness was found to be 3303.5µm in rGO/PUA which consists of 80% GO and 20% PUA. Lower values of standard deviation can be interpreted as less difference between the readings, which in this case means more evenness in the coating. In the case of Sample 1, which has the lowest average thickness, 313.5µm thickness was added to the fabric due to coating.
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This is because it contains the highest amount of PUA, which is more fluid than the Graphene oxide resin. It was observed during preparation that the solution was difficult to emulsify due to the high amount of PUA. The solution was unstable and had high fluidity. During coating, the solution seeped through the fabric rather than being deposited on the surface. Due to this, there was a loss of the solution and hence the thickness was lower. The maximum amount of thickness addition can be seen in the sample with 80-20% GO/PUA, having 330.5 µm average
thickness. However, the standard deviation, in that case, is very high, which implies uneven coating.
Knitting fair from the above results, it is evident that the production of cotton fabric with waterproof with the breathable property was possible through rGO while PUV act as nucleation between the cotton fabric and rGO. The optimum combinations that yielded the best performance in terms of waterproof properties and breathability are samples with 80-20% rGO-PUA. These combinations can be used to create active wear that can be worn in harsh conditions as well as for regular wear apparel. Based on the standard test result of waterproof testing shows that increasing the concentration of rGO give a better result with comfort property, as results the concentration of making good breathable waterproof fabric was 80% rGO and 20% PUA.
Source: textiles school
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Carbon fiber is a super strong material that is extremely lightweight. It is five times as strong as steel, two times as stiff, yet weighs about two-thirds less. Carbon fiber is basically very thin strands of carbon (even thinner than human hair). The strands can be twisted together, like yarn and then be woven together, like cloth. To make carbon fiber take on a permanent shape, it can be laid over a mold and coated with a stiff resin or plastic. Carbon fiber can also be defined as a fiber containing at least 92 wt % carbons.
Carbon fibers are a new breed of high-strength fiber. It came into existence in 1879 when Edison took out a patent for the manufacture of carbon filaments suitable for use in electric lamps. However, in the early 1960s, when there was a need f of the aerospace industry – especially for military aircraft – for better and lightweight materials, successful commercial production started.
In recent decades, carbon fibers have found wide usage in aeronautics, athletic performance, automobiles, building structures and, of course, musical instruments. Carbon fibers are used in composites with a lightweight matrix.
Carbon fiber composites are ideally suited for applications where strength, stiffness, lower weight, and outstanding fatigue characteristics are critical. They are used in the occasion where high temperature, chemical inertness, and high damping are important. They have been extensively used in composites in the form of woven textiles, prepregs, continuous fibers/roving, and chopped fibers. The composite parts can be produced through filament winding, tape winding, protrusion, compression molding, vacuum bagging, liquid molding, and injection molding.
There are two most important precursors in the carbon fiber industry are polyacrylonitrile (PAN) and mesophase pitch (MP). The structure and composition of the precursor affect the properties of the resultant carbon fibers significantly. Although the essential processes for carbon fiber production are similar, different precursors require different processing conditions in order to achieve improved Performance.
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Examples of Application
Aerospace – flights, rockets, satellites
Environment and Energy-related – wind power blade, tube power tank, battery charging flywheel, fuel cell, tidal power blade, the electric cable core
Auto-mobile – hood, roof, propeller shaft, body panel for the bus, compressed natural gas tank
Industrial use- the body of trains, x-ray top panel, pc housing, robot hand for liquid crystal panel, bridge pier reinforcement
Sports material – fishing rod, bicycle, hockey stick, racket, golf shaft.
Benefits of Carbon fiber
The potentially low-cost carbon fiber composites will be in a position to provide enormous advantages to a number of technologies for current and future everyday life applications, including a number of advanced technologies that are not currently commercially feasible. Lightweight components for automobiles, buses, trains, aircraft, ships, and applications including lightweight panels and load-bearing structures could result in weight savings, leading to a major saving in the nation’s and world’s energy consumption.
Low-cost carbon fiber is a national goal towards accomplishing a number of manufacturing technological breakthroughs.
Difficulties of Carbon Fiber
Cost is the main hurdle carbon fiber will have to overcome before it can provide a viable energy solution.
The second hurdle is waste disposal. When a typical car breaks down, its steel can be melted and used to construct another car (or building, or anything else made of steel). Carbon fiber can’t be melted down, and it’s not easy to recycle. When it is recycled, the recycled carbon fiber isn’t as strong as it was before recycling.
Lack of high-speed composite fabrication techniques
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Classification and types of carbon fiber
Based on modulus, strength, and final heat treatment temperature, carbon fibers can be classified into the following categories:
Based on carbon fiber properties, carbon fibers can be grouped into:
Ultra-high-modulus, type UHM (modulus >450Gpa)
High-modulus, type HM (modulus between 350-450Gpa)
Intermediate-modulus, type IM (modulus between 200-350Gpa)
Low modulus and high-tensile, type HT (modulus < 100Gpa, tensile strength > 3.0Gpa)
Super high-tensile, type SHT (tensile strength > 4.5Gpa)
Based on precursor fiber materials, carbon fibers are classified into:
PAN-based carbon fibers
Pitch-based carbon fibers
Mesophase pitch-based carbon fibers
Isotropic pitch-based carbon fibers
Rayon-based carbon fibers
Gas-phase-grown carbon fibers
Based on final heat treatment temperature, carbon fibers are classified into:
Type-I, high-heat-treatment carbon fibers (HTT), where final heat treatment temperature should be above 2000°C and can be associated with high-modulus type fiber.
Type-II, intermediate-heat-treatment carbon fibers (IHT), where final heat treatment temperature should be around or above 1500?C and can be associated with high-strength type fiber.
Type-III, low-heat-treatment carbon fibers, where final heat treatment temperatures not greater than 1000?C. These are low modulus and low strength materials.
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Manufacturing of Carbon fibers
Carbon fiber is a super strong material that is extremely lightweight. Carbon fibers generally have excellent tensile properties, low densities, high thermal and chemical stabilities in the absence of oxidizing agents, good thermal and electrical conductivities, and excellent creep resistance. Therefore Carbon fiber is enabling advancement in aeronautics, athletic performance, automobiles, building structures and, of course, musical instruments.
Carbon fibers are manufactured by a controlled pyrolysis of stabilized precursor fibers. First Oxidization process is done wherein the stabilization of precursor fibers at about 200-400 °C in air is done. Then carbonization is done wherein these fibers which are stabilized and infusible are treated at a high temperature of about 1,000 °C in an inert atmosphere to remove hydrogen, oxygen, nitrogen, and other non-carbon elements.
Then graphitized is done on those carbonized fibers at an even higher temperature up to around 3,000 °C to achieve higher carbon content and higher Young’s modulus in the fiber direction. The properties of the resultant carbon/graphite fibers are affected by many factors such as crystallinity, crystalline distribution, molecular orientation, carbon content, and the number of defects. The resulting carbon fibers are then post-treated to improve their adhesion to composite matrices.
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Source: textileschool
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