## Materials and Methods
### Bleaching with hydrogen peroxide
#### 2.2.3 Testing and Analysis  
The K/S values of the denim fabrics were measured using the spectrophotometer (X-rite Color I 7, Grand Rapids, MI, USA; subsidiary of Danaher, Washington, D.C., USA), and each sample was made 10 times, and the average value was taken.  
The fabric strength tester produced (YG026H, Wuhan Guoliang Instrument Co., Ltd., Hubei, People's Republic of China) was used to measure the tensile strength values of denim fabrics in the warp and weft directions according to GB/T3923.1-1997 [21].  
The change of denim fabrics weight was ensured by an electronic balance (LD, Shenyang Longteng Electronics Co., Ltd, Liaoning, People's Republic of China), tested 10 times and averaged data.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Method** & **Parameters** & **Values** & **Method** & **Parameters** & **Values** \\ \hline \multirow{5}{*}{Enzyme bleach} & Liquor ratio & 1:10 & & Liquor ratio & 1:14 \\  & Cellulose enzyme (g/L) & 1 & & Hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)) (o.w.f) (\%) & 8 \\  & Temperature (\({}^{\circ}\)C) & 25 & H\({}_{2}\)O\({}_{2}\) bleach & Sodium hydroxide (NaOH) (g/L) & 2 \\  & Time for cellulose enzyme (min) & 15 & & Time (min) & 15 \\  & Sodium carbonate (Na\({}_{2}\)CO\({}_{3}\)) (g/L) & 3 & Temperature (\({}^{\circ}\)C) & 80 \\  & Time for Na\({}_{2}\)CO\({}_{3}\) & 5 & & \\ \hline \multirow{5}{*}{NaClO bleach} & Liquor ratio & 1:14 & & \\  & Sodium hypochlorite (NaClO) (mL/L) & 14 & & Potassium permanganate (KMnO\({}_{4}\)) (g/L) & 20 \\  & Sodium carbonate (Na\({}_{2}\)CO\({}_{3}\)) (g/L) & 10 & & Time for KMnO\({}_{4}\) (min) & 5 \\  & Time for NaCO and Na\({}_{2}\)CO\({}_{3}\) (min) & 10 & & Phosphoric acid (H\({}_{3}\)PO\({}_{4}\)) (g/L) & 10 \\  & Temperature for NaClO and Na\({}_{2}\)CO\({}_{3}\) (C\({}^{\circ}\)C) & 50 & KMnO\({}_{4}\) bleach & Time for H\({}_{3}\)PO\({}_{4}\) (min) & 10 \\  & Sodium thiosulfate (Na\({}_{2}\)SO\({}_{3}\)CH\({}_{3}\)) (g/L) & 4.2 & & Temperature for KMnO\({}_{4}\) and H\({}_{3}\)PO\({}_{4}\) (C\({}^{\circ}\)C) & 50 \\  & Time for Na\({}_{2}\)S\({}_{2}\)O\({}_{3}\)5H\({}_{2}\)O (m) & 5 & Oxalic acid (H\({}_{2}\)C\({}_{2}\)O\({}_{4}\)H\({}_{2}\)O) (g/L) & 2.5 \\  & Temperature for Na\({}_{2}\)S\({}_{2}\)O\({}_{3}\)CH\({}_{3}\)O (\({}^{\circ}\)C) & 25 & Time for H\({}_{2}\)C\({}_{2}\)O\({}_{4}\)H\({}_{2}\)O (\({}^{\circ}\)C) & 25 \\ \hline \hline \end{tabular}  
The air permeability of denim fabrics would be measured by an air permeability tester (YG461E, Wuhan Guoliang Instrument Co., Ltd., Hubei, People's Republic of China) according to GB/T 5453-1997 [22].  
The thickness tester (YGB141D, Wenzhou Darong textile standard instrument factory, Zhejiang, China) was used to determine the thickness of the fabrics according to the national standard GB/T1380-1997.  
The color fastness to rubbing was tested by a rubbing fastness tester (Y571N, Nantong Hongda Experimental Instrument Co., Ltd., Jiangsu, People's Republic of China), where each sample was examined of dry and wet, and the gray scale according to GB/T 3920-2008 [23].  
The crease recovery angle had been measured with a fabric crease elasticity tester (YGB541D, Wenzhou Darong textile standard instrument factory, Zhejiang, People's Republic of China), and each sample was cut \(2.5\times 5\) cm\({}^{2}\) then tested 10 times, according to GB/T 3819-1997 [24].  
The morphology was observed using scanning electron microscopy (SEM) (JSM-6510 LV, Japan Electronics Co., Ltd., Japan).