An Innovative Approach to Enhance the Durability and Sustainability of Shoe Insoles

Abstract

This study presents an innovative approach to designing a shoe insole with enhanced durability, sustainability, and antibacterial properties. Needle-punched non-woven recycled polyester fabrics with three different GSMs (100, 200, and 300) were developed. The composite shoe insole was developed using non-woven fabric laminated with a polyurethane sheet to enhance durability. The fabrics were treated with an antibacterial finish with three different concentrations (5%, 10%, and 15%) and subjected to 5 and 10 washing cycles. The developed composites were evaluated against their relative hand value, abrasion resistance, tensile strength, antibacterial activity, and overall moisture management capability. Overall results reveal that the developed composite shoe insole is durable, sustainable, and presents no bacterial growth, demonstrating the insole’s hygienic effectiveness.

1. Introduction

One of the fastest-growing segments of technical textiles is medical textiles, which includes products like bio-scaffolds, bandages, dressing materials, personal protective equipment (PPE), and medicated footwear [1]. These medically formulated shoes are designed to reduce people’s discomfort with specific foot issues. Diabetes and foot ulcers are the two conditions that frequently call for these shoes [2]. It is essential to consider that the textile materials used to make insoles should be comfortable, breathable, stretchy, robust, and sustainable [3]. Sustainability is an essential aspect of product development, and through recycling, the need for raw materials and valuable natural resources is significantly reduced. Recycled polyester (rPET) is made from recycled plastic. It is an excellent way to prevent plastic from ending up in the trash [4]. Compared to fresh polyester, rPET requires much fewer resources and emits less CO₂. It is a robust, flexible, and durable material manufactured from synthetic fibers, just like traditional (or virgin) polyester [5]. In addition, rPET is an excellent heat insulator, lightweight, breathable, promotes optimal ventilation, and reduces sweat accumulation [6]. The non-woven technique can enhance comfort, as non-woven insoles provide cushioning, support, and protection for the foot. For insoles, durability plays a crucial role in terms of reuse [7]. Polyurethane (PU) is exceptionally durable since it has been utilized as a special coating for heavy-duty and industrial applications. It has shock absorption properties and does not break or wear out quickly. PU is much better than most synthetic leather substitutes. It can be utilized as a lamination for insoles since it is more durable than thermoplastics [8]. The direct contact between insoles and human skin necessitates their antibacterial properties. Wearing shoes for an extended period can lead to perspiration on our feet, which can harbor bacteria and give off an unpleasant odor [9]. Antibacterial finishes can aid in solving this issue. A textile with an antimicrobial finish ideally satisfies the needs of the consumer by being effective against a variety of bacterial and fungal species while being low in toxicity, non-irritating, hypoallergenic, and preserving the natural flora of nonpathogenic microorganisms that reside on the skin of the wearer [10]. The demand for antimicrobial fabrics has grown by double digits during the last few years. For that matter, the shoe insole industry has achieved notable growth as customers become more aware of sustainable and health-conscious products [11].

Consequently, researchers have extensively focused on developing shoe insoles to address these demands and meet customer expectations. Bratchenya et al. found that bamboo fiber absorbs more moisture and is more potent than viscose, which validates its usage in eco-friendly insoles [12]. Rajan et al. claimed that the most suitable spacer textiles for balancing permeability and thermal qualities are those with moderate porosity and a thickness of around 3 mm for insoles [13]. Fatkullina et al., in their findings, demonstrate that low-temperature plasma-treated felt layers enhance water absorption and antimicrobial qualities, making them a suitable option for rehabilitation footwear [14]. Zhao et al.‘s research shows that although silicone insoles are long-lasting, their uneven surface and softness might be uncomfortable for the user [15]. Azam et al. combined natural fibers such as tencel/flax and bamboo/hemp with alginate hydrogel to create environmentally friendly shoe insoles. This composite showed improved overall moisture management capability (OMMC) and tensile strength by crosslinking via a sol-gel process. The final product reduced odor, created a dry foot environment and exhibited environmental sustainability [16]. Shuhua et al. focuses on developing antibacterial composite fibers from poly(ethylene terephthalate) (PET) by combining it with antibacterial components using a twin-screw extruder. These fibers, produced through high-speed melt-spinning, have over 90% antibacterial activity while retaining significant mechanical qualities. The findings indicate that such antibacterial PET composites might be efficiently used in footbeds to improve comfort and hygiene in shoe insoles [17].

Lum et al. found that cork was more biodegradable and used fewer resources in a comparison of the environmental effects of cork and rubber/plastic insoles; however, cork has drawbacks such as poor cushioning and water sensitivity, which need careful consideration before it is widely used [18]. In previous research focusing on insole manufacturing, techniques such as needle punching and heat bonding were used to improve fiber tangling and surface texture uniformity in non-woven materials. Spacer cloth production techniques have also been employed to enhance compression and texture. Furthermore, layering has been widely used, whereas polymer lamination has been used to promote durability and maintain structural integrity, notably minimizing distortion after washing [19].

As mentioned above, many insoles are available in the market for various purposes, specifically for their antibacterial properties, but somehow, they all lack durability, which is the feature that ought to be most important for an insole. In this research, we are developing an antibacterial shoe insole designed to meet high durability requirements through PU lamination while utilizing non-woven rPET to ensure comfort and sustainability. Additionally, the insole is treated with a Silvadur^® finish to provide long-lasting antibacterial properties, making it a suitable option for everyday use. By combining these materials, we aim to develop an innovative, durable, and eco-friendly product that offers excellent performance, comfort, and hygiene.

Durable and hygienic shoe insoles are becoming more and more necessary, particularly for people with foot issues like infections and ulcers. Many insoles in the market today are not suited for prolonged usage because they either break down easily or do not offer antibacterial protection. Furthermore, there is a market for environmentally friendly insoles that still offer comfort and functionality due to the growing emphasis on sustainability. By providing a solution that blends sustainability, durability, and antibacterial qualities, this insole seeks to solve these problems and improve overall comfort and foot health. Though laminated textiles are used in many fields, there is not much work done on using this technique to increase the durability of sustainable materials in shoes. This study shows that the insole’s durability and wear resistance are significantly increased without sacrificing its sustainability by using PU lamination on RPET. The innovative approach of applying polymer lamination to create a long-lasting, environmentally friendly footbed meets the demands of the footwear industry for both performance and environmental responsibility. Innovative footwear design is vital because it directly affects the health and well-being of people, particularly those who suffer from infections and foot ulcers. Furthermore, by emphasizing sustainability in this subject, wider environmental issues are addressed while guaranteeing that the demands of those with limited resources are satisfied.

2. Experimental

2.1. Materials

Recycled polyester (rPET) fibers were sourced from Gulf Fiber Company Pvt. Ltd. (Lahore, Pakistan) with a length of 38 mm, a linear density of 1.47 deniers, and a tenacity of 48.55 N/tex. A polyester-based PU lamination sheet with 18 g per square meter (GSM) and a breathability of 38.454 g/h·m² was generously provided by Chawla Enterprises in Faisalabad, Pakistan. Silvadur^® 930FLEX Antimicrobial finish was purchased from DuPont^®.

2.2. Design of Experiment

Using the Design of Experiments (DOE) methodology, an experiment was designed to examine the effects of input factors on response variables (

Table 1. Factors and their respective levels.

Factors	Levels
GSM of Non-woven Fabric	100	200	300
Finish Concentration (% on the weight of fabric)	5	10	15
Washing	0	5	10

). Full factorial design was created by using Minitab^® 18 software as shown in

Table 2. Design of experiment.

Run Order	Samples	GSM	Antibacterial Finish	Washing
1	F	200	15%	0 cycles
2	G	300	5%	5 cycles
3	R	300	15%	5 cycles
4	Y	300	5%	10 cycles
5	X	200	15%	10 cycles
6	B	100	10%	0 cycles
7	E	200	10%	0 cycles
8	S	100	5%	10 cycles
9	K	100	10%	5 cycles
10	C	100	15%	0 cycles
11	YZ	300	15%	10 cycles
12	L	100	15%	5 cycles
13	W	200	10%	10 cycles
14	U	100	15%	10 cycles
15	G	300	5%	0 cycles
16	Z	300	10%	10 cycles
17	H	300	10%	0 cycles
18	I	300	15%	0 cycles
19	T	100	10%	10 cycles
20	D	200	5%	0 cycles
21	V	200	5%	10 cycles
22	N	200	10%	5 cycles
23	J	100	5%	5 cycles
24	O	200	15%	5 cycles
25	Q	300	10%	5 cycles
26	M	200	5%	5 cycles
27	A	100	5%	0 cycles

. A full factorial design was used for our experiment because it allows for a comprehensive evaluation of all possible combinations of factors and levels, providing valuable insights into their interactions.

2.3. Methodology

2.3.1. Development of rPET Non-Woven Fabric

Non-woven fabrics of rPET with three different GSM (100, 200, and 300) were developed using the non-woven machine (Dongwong-roll Co., Ltd., Incheon, Republic of Korea) (Figure 1). For the web formation, the fibers were manually opened and passed through a series of machines, including a coarse fiber opening machine (DW-B/0), a fine opener (DW-F/0), a reserve hopper feeder (DW-C/H), a baby carding machine (DW-C/H), and a cross lapper (DW-C/L). Further, the created web was fed into a needle punching machine (DW/NP) with a 10 mm depth for the web bonding [16]. The non-woven recycled polyester (rPET) sample has high resilience and tensile strength, making it suitable for long-lasting shoe insoles. Its non-woven construction improves delamination resistance and ensures integrity under stress. Furthermore, the optimized GSM increases stretchability and overall performance [20]. Figure S21 shows the microscopic images of non-woven rPET with and without lamination and its structural differences across treatments.

2.3.2. PU Lamination

The non-woven fabrics were laminated with PU using a lamination machine (Jiangsu Kuntai Machinery Co., Ltd., Yancheng, China). This machine has two horizontal rollers; one roller passes the non-woven fabric, while the upper second roller passes the PU sheet. Both layers were fused with reactive polyurethane (PUR) hot-melt adhesive, poured from the side pipe. PUR is well known for its outstanding adherence to a variety of substrates, resulting in high bonding strength while being flexible. It also has high resistance to moisture, chemicals, and temperature changes, making it appropriate for a variety of applications, such as textiles and footwear. In this study, the adhesive used for lamination resisted up to ten washing cycles, maintaining its durability and assuring long-lasting performance [21]. After lamination, samples were dried for 24 h under ambient conditions.

2.3.3. Silver-Based Finish Application

The methodology was adapted from the literature and modified according to the study requirement to yield a composite insole having antibacterial characteristics (Figure 2). At first, the colloidal solution of Silvadur^® was diluted into three different concentrations of 5%, 10%, and 15% with distilled water at room temperature (24 °C). The finish was applied to the fabric through the pad–dry–cure method by dipping the samples in the prepared solution and ensuring a thorough soaking. Excessive solution from the samples was removed by passing them through padding rollers at a constant pressure of 2 bars. Further, samples were dried and cured at 150 °C for 3 min in a curing machine (Dongwong-roll Co., Ltd.) [22].

2.3.4. Washing

Samples were washed according to ISO 105-C03 [23]. In this method, a soap solution (5 gm soap and 2 gm anhydrous sodium carbonate per liter of water) was used at 60 °C for 30 min per cycle [24]. Samples were subjectsesd to 5 and 10 washing cycles to evaluate the fabric’s antibacterial performance and durability. This washing test aimed to ascertain how such harsh washing conditions would affect the fabric’s strength and surface texture.

2.4. Characterization

2.4.1. Relative Hand Value Test

The relative hand value (RHV) indicates a consumer’s overall response to a fabric [25]. It was evaluated using the fabric assessment system Phabrometer under the AATCC-202 standard [26]. The RHV assessment was conducted using a sample size of diameter 11 cm. This standard predicts the tactile sensations humans experience while handling the fabric. This system measures the values of the fabric’s resilience, softness, smoothness, and wrinkle recovery rate [27].

2.4.2. Moisture Management Test

The OMMC index measures the fabric’s overall capacity to control liquid moisture transport [28]. This study used the AATCC TM 195 standard [29] to determine the OMMC. In this standard, a sample (diameter 11 cm) was placed in the apparatus horizontally between the upper and lower sensors to analyze the liquid transport characteristics of the fabric. These sensors are composed of concentric rings of pins. A solution was dropped on the upper surface of the sample without any pressure applied [30].

AATCC TM 195; Liquid Moisture Management Properties of Textile Fabrics.

2.4.3. Antibacterial Test

The antibacterial activity of treated fabric was conducted through qualitative and quantitative methods. A qualitative method was employed by using S. aureus as a gram-positive bacteria according to the AATCC147 standard [31]. In this procedure, bacterial culture was scattered randomly on the surface of the agar plate. The test was performed using a sample size of 1 × 1 inch. The bacteria under the fabric were monitored by placing the fabric samples (2.5 cm × 2.5 cm) on the agar plate and incubating at 37 °C. The absence of bacterial growth on samples evidenced the antibacterial activity of the fabric [32].

The quantitative method accurately assesses the percentage of bacterial growth inhibition according to the AATCC100 standard [33]. In this standard, a fabric sample (4 cm × 4 cm) is used with 100 mL of bacterial culture solution containing 1 × 10⁵ CFU/mL. The samples were then incubated at 37 °C for 24 h. Following incubation, the bacteria were removed from the fabric by vigorously shaking the samples in 100 mL of neutralizing solution for 1 min using a vortex mixer. The bacterial count was subsequently accessed through serial dilution and plating on nutrient agar. Two contact time assays were performed: the zero contact time assay, where bacteria was eluted right after inoculation, and the 24 h contact time assay, which elutes bacteria after 24 h of exposure. The antibacterial effectiveness was calculated using the formula

$$\mathrm{B}\mathrm{a}\mathrm{c}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{i}\mathrm{a}\mathrm{l} \mathrm{r}\mathrm{e}\mathrm{d}\mathrm{u}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\left(\mathrm{\%}\right)={\displaystyle \frac{(\mathrm{B}-\mathrm{A})}{\mathrm{B}}}\times 100$$

(1)

In Equation (1), B represents the bacterial colonies at 0 contact time and A signifies the count after 24 h [34].

2.4.4. Tensile Strength

The tensile strength of fabric samples was determined according to the ISO 13934-1 standard [35]. This method is also known as the grab test, which determines the maximum force a fabric can withstand [36]. The test was performed using samples with dimensions of 17 inches in length and 2.5 inches in width. The fabric sample was gripped from the upper and lower edges by jaws of a certain size and extended continuously until it ruptured. The point where the sample was ruptured with maximum force was recorded and measured in force per unit area [32].

2.4.5. Abrasion

Martindale abrasion tester was used to perform an abrasion test on the fabric samples according to the ISO 12947-2 standard (50,000 cycles for the laminated side and 20,000 cycles for the non-woven side) [37]. A circular fabric sample (10 cm × 10 cm) was mounted in a specimen holder. The fabric sample was rubbed against an abrasive medium while the specimen holder was rotating around its axis, perpendicular to the specimen’s plane, until a hole appeared or the material thinned to an unacceptable level [38].

3. Results and Discussion

3.1. Relative Hand Value

RHV quantitatively measures the tactile quality of the fabric. Resilience refers to the fabric’s resistance to deformation. It has been reported that fabric thickness, density, and structural integrity are the main factors that affect fabric resilience [39]. Higher GSM has more density, which provides better structural support and elasticity [40]. In this study, sample YZ (300 GSM) exhibited the highest value, while sample B (100 GSM) had the lowest value of resilience, as shown in Figure 3A, which supports the statement. However, antibacterial finish and washing mainly affect the fabric’s surface rather than altering core physical properties, leaving resilience unaffected [41]. Softness is related to the pliability of fabric. GSM affects the softness; heavier fabrics generally feel less soft due to their compact structure. Fabrics with lower GSM have fewer fibers per unit area, making them less dense and softer [42]. Sample B (100 GSM) has the highest softness, while sample Z (300 GSM) showed the lowest softness value, as shown in Figure 3B. Antibacterial finish and washing did not affect the softness for the same reasons identified regarding resilience.

Smoothness is related to fabric surface texture. According to the literature, GSM and washing affect the smoothness of the fabric [43]. However, in this study, the smoothness results fail to match the statement as shown in Figure 3C. Despite variations in GSM, finish, and washing, the consistent smoothness observed throughout the samples can be explained by the stability of the needle punching technique. This technique develops a robust and entangled fiber network that maintains a consistent surface texture for fabric [44]. Another attribute is the polymer lamination on the opposite side, which supports non-woven fabric and makes it less susceptible to changes from washing. This combination keeps the non-woven surface smooth and minimizes the impact of other factors [45]. The ability of a fabric to resist the formation of a crease or wrinkle when slightly squeezed is termed crease resistance. Polymer lamination has a significant effect on the wrinkle recovery rate due to its elastic nature. It recovers lower GSM faster than higher GSM samples because of its less dense structure and thickness, allowing the lamination to exert a more uniform and effective restorative force across the fabric sample, leading to quicker wrinkle recovery [46]. Sample U (100 GSM) showed the highest wrinkle recovery rate, and sample I (300 GSM) had the lowest, as shown in Figure 3D. As previously stated, the antibacterial finish and the washing process affect surface qualities rather than the fabric’s structure, explaining their lack of effect on wrinkle recovery [47].

After analyzing the graphs of RHV (resilience, softness, smoothness, and wrinkle recovery rate), a clear correlation between softness and wrinkle recovery rate can be observed. This indicates that fabric with higher softness tends to have a better wrinkle recovery rate, as reported in previous studies [48]. Softness and wrinkle recovery in the insole are correlated, as both increase when GSM is decreased. Softness is improved by reduced density and fewer fibers per unit area, and wrinkle recovery is improved by polymer lamination, which supports the non-woven side in recovering from wrinkles faster. The RHV results showed that among all samples tested, sample YZ stands out. This sample had 300 GSM, showing its durability and resilience with a 15% finish. Figures S1–S16 show the data and interaction plots that demonstrate the effects of GSM, finish concentration, and washing cycles on the RHV. The results allow for a statistical analysis of how each factor influences the tactile quality and durability of the samples. The sample also underwent ten washes, indicating that it maintains its properties well after repeated use, which is critical for a product like a shoe insole that experiences significant wear and tear.

3.2. Moisture Management

Moisture management is the ability of the fabric to absorb and wick away moisture. To determine the OMMC value in the AATCC TM 195 standard, the liquid is dropped on the surface without any pressure while analyzing its movement using specific metrics, such as absorption rate, wetting time, and spreading speed [49]. In this study, the standard resulted in a zero OMMC value for rPET non-woven samples, which means the fabric does not absorb any moisture in these testing circumstances due to the fabric’s surface tension and the hydrophobic nature of rPET. However, the sample absorbs moisture when slight pressure is applied, as shown in the Supplementary Video S1; the external force overcomes the surface tension, allowing the water to penetrate the fabric. The non-woven rPET fabric resists moisture under standard conditions but can absorb water when applying mechanical pressure, forcing the liquid into the inter-fiber spaces, as noted in previous studies [50]. This explains why the fabric absorbs water well under pressure while showing zero moisture management in the standard OMMC test. The standard test method may indicate a lack of moisture management as it does not fully capture the dynamic conditions experienced during real-life use, while practically all the samples can absorb sweat when foot pressure is applied to the insole.

3.3. Antibacterial Test

The non-woven rPET samples were pretreated with Silvadur^® antibacterial finish to evaluate their antibacterial activity using a qualitative method (AATCC147) and a quantitative method (AATCC100). In Silvadur^®, the active ingredient is silver ions (Ag⁺), which are known to prevent bacterial growth by affecting cellular processes. It also contains a polymeric carrier system, which acts as a stabilizing medium and regulates the release of silver ions. This method ensures the ions are delivered gradually, resulting in persistent antibacterial action.

3.3.1. Qualitative Antibacterial Test

In this method, a subset of 5 samples was selected from 27 samples to examine the antibacterial activity. Samples were selected based on the lowest and highest concentration (5–15%) of finish. This approach allows for a clear comparison of the extremes, providing insights into the effectiveness of the antibacterial treatment across different washing cycles (0, 5, and 10). The non-woven side of the samples faced the agar plate to note the bacterial growth under the samples [51]. According to the test results, no visible bacterial growth was observed under any samples, as shown in Figure 4 and

Table 3. Antibacterial efficacy of non-woven samples treated with Silvadur^® finish.

Samples	Antibacterial Finish	Washing Cycles	Bacterial Growth in the Sample Contact Area	Clear Zone Inhibition (mm)
P	5%	5	No	0.00
Y	5%	10	No	0.00
YZ	15%	10	No	0.00
G	5%	0	No	0.00
I	15%	0	No	0.00

. Hence, the samples treated with Silvadur^® finish inhibited the growth of S. aureus bacteria, thus showing antibacterial efficacy. In this study, a qualitative test was conducted with a single bacterial strain (S. aureus) to demonstrate the antibacterial efficacy of our samples, as extensive research has already shown the efficacy of the same antibacterial finish (Silvadur) against a broad range of microorganisms, including gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) and fungi [10].

The antibacterial test results showed no zone inhibition around the sample, demonstrating the zero inhibition zone, as shown in Table 3 This is due to the non-leaching nature of the antibacterial finish, which prevents it from spreading into the surrounding medium, consistent with existing knowledge [52].

3.3.2. Quantitative Antibacterial Test

The quantitative antibacterial assessment used 5 selected samples from a total of 27 samples in DOE, the same as in the qualitative method. An extra control sample was included for comparison (Figure 5). The results showed a considerable reduction in bacterial growth across all samples. The control sample C1 exhibited less than 10 ± 1% bacterial reduction due to the absence of an antibacterial finish, while sample I (15% finish, 0 wash) achieved a remarkable reduction of 91.25 ± 1.01%. Similarly, sample G (5% finish and 0 wash) also showed high efficacy with a reduction of 92.75 ± 1.24%, while sample YZ (15% finish, 10 washes) exhibited 85.03 ± 1% reduction, samples P (5% finish, 5 washes) and Y (5% finish, 10 washes) showed reductions of 82.3 ± 1.56% and 80.2 ± 1.50% respectively. This slight decrease in the efficiency of samples YZ, P, and Y can be attributed to the washing cycles, which most likely influenced the finish concentration, reducing antibacterial characteristics and resulting in slightly lower bacterial reduction percentages.

3.4. Tensile Strength Evaluation

Tensile strength refers to the fabric’s ability to bear the maximum force during stretching until it breaks. Sample I, with 300 GSM, 15% finish, and 0 washes, shows the highest, while Sample A, with 100 GSM, 5% finish, and 0 washings, shows the lowest tensile strength value, as shown in Figure 6. The data analysis demonstrates that an increase in GSM with an increase in finish concentration leads to a corresponding rise in tensile strength [40]. Higher GSM fabrics are more compact and have a denser structure, while the Silvadur^® finish enhances fiber bonding, increasing the material’s strength, as mentioned in the literature [10]. Conversely, washing has minimal effect on tensile strength, indicating that fabric retains its durability and strength even after multiple washing cycles [53]. The elongation data in the graph shows a balance of flexibility and tensile strength among the samples. They display materials capable of significant stretching before breaking, which is important for applications that need elasticity and durability. Figures S17–S20 exhibit data and interaction plots demonstrating the impacts of GSM, finish concentration, and washing cycles on tensile strength and provide the statistical significance of these parameters on the tensile performance and durability of the samples.

To determine the effect of lamination on tensile strength, a comparative analysis was conducted using a non-woven rPET sample without lamination as a control (C2). The control sample, with 100 GSM, had a tensile strength of 65N and an elongation of 85%. In contrast, sample A had the lowest tensile strength of the laminated samples, as mentioned above, with a tensile strength of 75N and an elongation of 56%. The lower elongation in the laminated sample is due to the restriction of the fiber movement imposed by the lamination process, but it increases its tensile strength by providing more structural support [54].

3.5. Abrasion Resistance

Abrasion resistance is a fabric’s capacity to withstand wear and tear from rubbing or friction. This test was performed on 6 samples of non-woven rPET selected from the 27 samples, using the Martindale method. The test was conducted on both non-woven and laminated sides of the samples. For each side, six samples were taken from the same fabric samples (B, U, W, N, I, and Z). Each sample varied in GSM (100, 200, and 300) and was treated with three different finish concentrations (5%, 10%, and 15%). Four samples were subjected to 5 and 10 washing cycles, while two were unwashed. Results showed that the non-woven side of the samples withstood up to 20,000 cycles without showing significant damage, as shown in Figure 7A. The only noticeable effect was the displacement of surface fibers. The primary contributing factors were the rPET fibers’ durability and wear resistance, as well as the fact that the non-woven structure evenly distributes the stress across the fabric, reducing localized damage, despite variations in GSM and finish concentration [55]. Additionally, the polymer lamination prevents the fibers from being easily displaced. The test was continued from the other (laminated) side of the samples to measure durability under extended wear conditions. This side of the samples lasted up to 50,000 cycles without damage, as shown in Figure 7B. This result highlights the outstanding durability of PU lamination while showing its capacity to sustain significant mechanical stress, supporting results reported in the literature [56]. Hence, the durable polyester fibers, non-woven structure, and PU lamination contributed significantly to the fabric’s integrity throughout the abrasion resistance testing.

4. Conclusions

This study investigated the potential of utilizing non-woven rPET with polymer (PU) lamination to develop a shoe insole. The material was characterized based on its durability, sustainability, and comfort, with the addition of a Silvadur^® finish to impart antibacterial properties. The findings demonstrate that when a fabric’s GSM increases, its resilience, smoothness, and tensile strength increase. Despite showing zero OMMC value under standard conditions, the insole adequately absorbs moisture under slight pressure, revealing its potential for moisture management in real-life situations. The abrasion resistance test determined that the non-woven side of the insole resisted up to 20,000 cycles, while the laminated side lasted up to 50,000 cycles, demonstrating the material’s durability. Furthermore, the antibacterial test confirmed no bacterial growth with zero zone inhibition, reinforcing the insole’s functional properties. The implications of these findings show that the insole meets the durability standards for footwear.