**3. Gamma irradiation on textile fabrics**

Gamma rays are high-energy electromagnetic radiations having energies above 100 keV and wavelengths less than 10 picometers. Surface modification of textiles using gamma ray is one of the promising methods.

The excellent mechanical properties, heat and oxidation resistance, and environmental stabilities make carbon fiber fabrics ideal reinforcing materials in the advanced composite fields, such as solar panel of space station and electric vehicle body. All these excellent properties depend largely on the interfacial adhesion which finally affects the overall property of the resulting composites. Recently, radiation-induced grafting has been extensively applied as a competitive methodology to develop new functional materials. An easy method to evenly functionalize the fabric surfaces by *γ*-ray irradiation grafting was reported. This novel technique is simple, green, and versatile. The functionalization was much more uniform compared with the traditional electrochemical method. The interfacial strength of the compo‐ sites had a dramatic increase [8].

Presently, polymeric membranes are extensively employed in the field of biomedical materials contacting with blood. Sulfonated polypropylene nonwoven fabric (PPNWF) has been successfully prepared via gamma-ray preirradiation-induced graft polymerization of sodium styrenesulfonate (SSS) and acrylamide (AAm) by li et al (**Figure 2**).

**Figure 2.** Schematic diagram of preparing sulfonated PP NWF via gamma-ray preirradiation method [9].

Gamma ray preirradiation-induced cograft polymerization has been extensively applied to modified polymer materials because of its simple procedure and even grafting. Acrylonitrile (AN) has been widely used in the modification of materials and an amidoxime group can be obtained by further chemical treatments from the nitrile group to increase adsorption effi‐ ciency for heavy ions. In a research that has been done in 2013 by Liu and his coworkers, a preirradiation-induced emulsion cograft polymerization method was used to introduce AN and AA onto a PE nonwoven fabric. The use of AA is meant to improve the hydrophilicity of the modified fabric. The modified nonwoven fabric is ready for further amidoximation to the application of heavy metal ion extraction [10].

In the other research, SSS was grafted onto PPNWF via *γ*-ray coirradiation method with the existence of *N*-vinyl-2-pyrrolidone. The modified PPNWFs presented good blood compatibil‐ ity, such as lower hemolysis rate and lower platelet adhesion. Besides, the modified PPNWFs prolonged the clotting time and presented excellent anticoagulant effect [11].

The textile industries are one of the major sources of water pollution in terms of releasing highly colored waste stream in surface water bodies. The wastewater generated in textile processing plants is contaminated with toxic synthetic colorants and various perilous chemicals. The main objectives of the study by Bhuiyan et al. were to degrade the dye molecules and organic pollutants of textile wastewater by using gamma irradiation followed by the investigation of physicochemical parameters of the irradiated water as well as looking into the scope for using treated wastewater for irrigation and dyeing purposes. The wastewater samples were submitted to Cobalt-60 gamma radiation source.

The excellent mechanical properties, heat and oxidation resistance, and environmental stabilities make carbon fiber fabrics ideal reinforcing materials in the advanced composite fields, such as solar panel of space station and electric vehicle body. All these excellent properties depend largely on the interfacial adhesion which finally affects the overall property of the resulting composites. Recently, radiation-induced grafting has been extensively applied as a competitive methodology to develop new functional materials. An easy method to evenly functionalize the fabric surfaces by *γ*-ray irradiation grafting was reported. This novel technique is simple, green, and versatile. The functionalization was much more uniform compared with the traditional electrochemical method. The interfacial strength of the compo‐

Presently, polymeric membranes are extensively employed in the field of biomedical materials contacting with blood. Sulfonated polypropylene nonwoven fabric (PPNWF) has been successfully prepared via gamma-ray preirradiation-induced graft polymerization of sodium

styrenesulfonate (SSS) and acrylamide (AAm) by li et al (**Figure 2**).

**Figure 2.** Schematic diagram of preparing sulfonated PP NWF via gamma-ray preirradiation method [9].

application of heavy metal ion extraction [10].

Gamma ray preirradiation-induced cograft polymerization has been extensively applied to modified polymer materials because of its simple procedure and even grafting. Acrylonitrile (AN) has been widely used in the modification of materials and an amidoxime group can be obtained by further chemical treatments from the nitrile group to increase adsorption effi‐ ciency for heavy ions. In a research that has been done in 2013 by Liu and his coworkers, a preirradiation-induced emulsion cograft polymerization method was used to introduce AN and AA onto a PE nonwoven fabric. The use of AA is meant to improve the hydrophilicity of the modified fabric. The modified nonwoven fabric is ready for further amidoximation to the

In the other research, SSS was grafted onto PPNWF via *γ*-ray coirradiation method with the existence of *N*-vinyl-2-pyrrolidone. The modified PPNWFs presented good blood compatibil‐ ity, such as lower hemolysis rate and lower platelet adhesion. Besides, the modified PPNWFs

The textile industries are one of the major sources of water pollution in terms of releasing highly colored waste stream in surface water bodies. The wastewater generated in textile

prolonged the clotting time and presented excellent anticoagulant effect [11].

sites had a dramatic increase [8].

312 Radiation Effects in Materials

The irradiated wastewater was found to be recyclable in textile wet processing and reusable for irrigation purposes [12, 13].

The presence of toxic metals and pathogenetic microbes in drinking water is a potential health risk. Consequently, numerous investigations have been carried out on the functionalized polymer membrane with AgNPs as effective antimicrobial agents for water treatment. Unfortunately, the AgNPs were commonly inert with polymer surfaces so that silver releases into water filtrate in an overdose compared to the permitted limit of standard at maximum of 0.1 mg/L, according to the US Environmental Protection Agency (EPA) and World Health Organization (WHO).

A new method to immobilize AgNPs onto the acrylic grafted polyethylene nonwoven (PE) fabric by gamma Co-60 irradiation for drinking water treatment has been described in 2013.

The PE fabric pieces were treated by a mixture of acetone/H2O solution and dried before irradiation. The PE fabric samples were irradiated at the required doses up to 50 kGy by γ ray from Co-60 source. Thereafter, the graft reactions were carried out at ∼90°C in a flask con‐ taining 1 g preirradiated PE, 0.05 g Mohr's salt and AA with concentrations of 10–50% (v/v) in 100 ml aqueous solution. The PE-g-PAAc samples were soaked overnight at room temperature in Ag NPs colloidal solutions and then squeezed to remove the excess Ag NPs, rinsed with pure water and dried in an oven at 70 C for 2 h. The dried fabrics were then annealed at 120 C for 1 h for esterification of –COOH group of PAAc with –OH group of Polyvinyl alcohol (PVA). The prepared fabrics contained about 10,000 ppm Ag NPs showing strong bactericidal efficiency against *Escherichia coli*. Based on the strong bactericidal efficiency and under permitted limit of silver release into water filtrate, PE-g PAAc/Ag NPs fabrics can be used for the treatment of drinking water. Also, this kind of filters can be used in air cleaners and have other applications [14].

In the other research, the silver ions have been reduced effectively by gamma irradiation and immobilized on the cotton fabrics by in situ synthesis. The Ag NPs content deposited on the fabrics was of 1696 mg/kg, when the fabric sample was irradiated in 1.5 mM Ag NO and 1.0% chitosan solution at the dose of 13.8 kGy at 30°C.

Antibacterial efficacy of the Ag NPs fabrics after washing 40 cycles of washing was about 99.99% for *Staphylococcus aureus* and *E. coli*. The AgNPs/cotton fabrics washing from 1 to 40 cycles were innoxious to skin (k = 0). These results confirm that gamma irradiation of cotton fabrics in the presence of AgNO and chitosan solution is a promising approach for preparation of stable, safe, and efficacious antibacterial fabrics [15].

In the past decades, the materials with high water and oil repellency have attracted much attention from researchers and industries. The perfluoroalkyl phosphate acrylates have been grafted onto a cotton fabric via gamma-ray irradiation to improve the hydrophobic and oleophobic properties.

**Figure 3.** Photographs of water and sunflower oil drops on the grafted sample [16].

The results show that the fabric became highly hydrophobic and oleophobic with the contact angles of above 150o and 140o for water and sunflower oil, respectively (**Figure 3**) [16].

In the other research, a novel coating formulation for improving the UV protection property on cotton, PET, and cotton/PET fabrics was prepared, and gamma rays were applied for surface curing. Aluminum potassium sulfate (Alum) was used individually and in binary coat with Zinc Oxide (ZnO), to induce the UV-blocking properties [17].
