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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