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Abstract

Low-stress mechanical properties are essential in enhancing comfort, durability, and aesthetic attributes. These properties significantly influence fabrics’ overall performance and tactile comfort in various applications. Meta-aramid yarn was used to develop the fire protective station wear of various weave structures like plain, basket, and ripstop. The linear density of the yarn was 29.5 Tex, and three different PPCs (picks per centimetre) of 15.7, 18.1, and 20.5 were considered for the manufacture of the fabrics. The low-stress mechanical properties such as tensile properties (tensile linearity and tensile energy), shear properties (shear hysteresis (2HG and 2HG5) and shear rigidity), bending properties (bending rigidity, bending hysteresis), and compressional energy were investigated using the Kawabata evaluation system (KES). The effect of weave structures on the low-stress mechanical properties of various fabrics was analysed. The linearity of the tensile load extension curve (LT) and the tensile resilience (RT) increased with the increase in weft density for all the weave structures. It was observed that increasing the PPC from 15.7 to 20.5 improved the linearity of the load-extension curve, with LT values rising from 0.38 to 0.58 for plain weave, and increased tensile energy (WT) from 3.55 to 7.3 g.cm/cm² for plain weave and from 3.32 to 6.55 g.cm/cm² for basket weave. Surface roughness (SMD) also decreased, with values dropping from 10.39 µm to 8.81 µm for plain weave. A complex relationship between weave structure and PPC needs to be considered when optimizing the design and performance of station wear fabrics.

Keywords

fire protective clothing station wear uniform picks per centimetre weave structure low-stress mechanical properties

Introduction

The primary purpose of firefighter clothing is to protect firefighters from fire and extreme temperatures. However, it is equally important that their gear exhibits exceptional functionality, allowing firefighters to perform their duties with maximum efficiency and minimal energy expenditure, while also ensuring high visibility and easy identification in hazardous situations.^1–5 Fire protective suits are often required to withstand multiple exposures during firefighting operations.¹ In recent years, there has been increasing recognition of the importance of incorporating physiological comfort considerations into the design of firefighters’ clothing.^6,7 The different layers of a protective suit are designed to provide specific levels of protection while also contributing to the overall comfort of the wearer³ (Figure 1). These suits consist of an inner fabric (thermal lining), a middle layer (moisture blocker), and an exterior fabric (outer layer).⁸ The outer layer of fire protective fabrics mainly protects the rescuer from extreme heat and wear hazards. The moisture barrier serves as a defense against water, vapours, and hot chemicals. The thermal liner functions as a thermal barrier, protecting the wearer from ambient heat.⁹ Station wear refers to the uniform used by the fire rescuers at the fire station, typically comprising a knitted or woven shirt or long-sleeve shirt paired with trousers. In an emergency situation, structural turnout gear is worn over the station wear uniform or other base layers.¹⁰ To achieve optimal protection and comfort, a thermal liner treated with aerogel was utilized in research.¹¹ The researcher analysed the water vapour transmission of the clothing, which has a significant impact on the fabric’s comfort properties.^12,13 The analysis of textiles using the Kawabata Evaluation System and other experimental techniques primarily relies on comparative assessments rather than definitive ‘pass’ or ‘fail’ criteria. Consequently, a comprehensive dataset for comparison is essential to accurately characterize the fabrics under evaluation.^14–16 Sensory or tactile comfort, often referred to as the ‘handle’ or ‘hand’, is a crucial component of overall physiological comfort. The level of this comfort can be quantified using various techniques, with the most common approach being the objective evaluation of fabrics through the four modules of the Kawabata Evaluation System. This methodology provides an alternative, unbiased means of assessing fabric characteristics, thereby eliminating the need for subjective evaluations by a panel of skilled professionals. A fabric that provides comfort in low-humidity conditions may lead to discomfort in high-humidity or perspiration scenarios. This is because moisture between the fabric and the skin increases friction, which can heighten the sensation of roughness.¹⁷ Consequently, a fabric that feels comfortable in dry conditions may become uncomfortable when exposed to high humidity or sweating. Researchers have found that moisture on the skin has a more significant effect on fabric-to-skin friction than the type of fibre or the structural properties of the fabric.^18,19 The frictional force was found to be directly proportional to the density of the weft yarn, provided the yarn count remains constant. This effect is likely due to an increase in yarn crimp, which creates a knuckle effect.²⁰ Another investigation revealed that increased friction between the fabric and the skin, due to moisture absorption, can lead to discomfort in the underlying skin.²¹ The fabric-to-metal surface and fabric-to-fabric friction in various fabrics were analysed, and a logarithmic relationship with fabric friction, influenced by fibre type, blend proportion, yarn structure, and compressibility, was formulated in that study. The frictional force increases as the cellulose fibre components increase.²³

Figure 1.

Different layers of a turnout gear with station wear uniform.

In another study, the impact of micro denier polyester yarns on the low-stress mechanical properties of polyester-cotton fabrics was analysed. It was found that, except for shear properties, all mechanical properties remain consistent, with no change in fabric handles and low air permeability values compared to regular yarn fabrics.²² An independent investigation into fabrics made from micro denier polyester filament yarns found that the relationship between surface friction and variations in micro denier filaments, from coarser to finer, was not consistently predictable. However, fabrics produced from the finest denier fibres exhibited the lowest surface roughness.²³ In addition to fabric structure, fabric roughness is influenced by factors such as the blend ratios of different fibres, yarn structure, and fabric compression. The frictional properties of materials used in fabric components can vary, affecting the overall frictional characteristics of the finished fabrics, depending on the selection and blending ratios of the materials.^24–26 Moreover, it has been demonstrated that different fabric treatments, such as bleaching, dyeing, and finishing, increase friction and roughness in knitted cotton fabrics. The washing process also affects the surface properties of materials, with structural qualities of the fabric being more influential than the washing temperature.²⁷ Therefore, the tactile comfort of a fabric is significantly influenced by its surface characteristics and physical properties. Fabrics with poor smoothness in contact with the skin can cause discomfort, requiring greater effort for bodily movement and joint flexibility.²⁸

Thermo-physiological comfort refers to how heat and moisture move through clothing, while sensory comfort involves how the fabric feels when it comes into contact with the skin. The fabric’s texture properties influence tactile comfort, which focuses on how well the clothing fits the body in terms of size and shape along with the mechanical properties. The most critical aspect is the physiological comfort, that is, how well heat and moisture pass through the fabric to balance the body’s temperature and environment.²⁹

Examining the impact of thread density on fabric performance is also crucial. An increase in the number of threads per centimetre can enhance fabric strength and resistance to hazardous conditions; however, this improvement may compromise wearer comfort due to reduced airflow. To enhance the effectiveness of the study, it is important to include specific requirements for firefighting, such as heat resistance, flame protection, moisture absorption, and mobility. Conducting investigations on fabric structures and thread densities under conditions that simulate actual firefighting scenarios could provide valuable insights. This research aims to explore the effects of fabric structure and thread density on the sensory attributes of firefighter station wear uniforms.

Materials and Methods

Materials

All fabric samples were developed on the handloom with constant EPC (ends per centimetre) 16.5. The material used for the samples is Nomex IIIA yarn. The linear density of Nomex IIIA yarn is 29.5 Tex. The pick densities (picks per centimetre) of the samples were 15.7, 18.1, and 20.5, respectively (Table 1). Plain (PL) weave, along with its two derivatives basket (BS) and ripstop (RS) were selected here for the evaluation of the low stress mechanical properties (Figure 2).

Table 1.

Particulars of fabric samples.

Sample code	Weave	EPC	PPC	Areal density (g/m²)	Thickness (mm)
PL1	Plain	16.5	15.7	106.1	0.442
PL2	Plain	16.5	18.1	112.16	0.472
PL3	Plain	16.5	20.5	120.35	0.466
BS1	Basket	16.5	15.7	117.4	0.482
BS2	Basket	16.5	18.1	133.2	0.478
BS3	Basket	16.5	20.5	140	0.492
RS1	Ripstop	16.5	15.7	125.9	0.438
RS2	Ripstop	16.5	18.1	133.2	0.441
RS3	Ripstop	16.5	20.5	143.9	0.448

Figure 2.

Various weave structures: (a) plain (PL), (b) basket (BS) and (c) ripstop (RS).

Methodology

Sample Preparation for Measuring the Hand Value

The chemical processing followed after the weaving is shown in Figure 3.

Figure 3.

Different process sequences for the chemical treatment of meta-aramid station wear.

After the collection of greige fabric from the loom, the desizing process was completed. After that, proper washing and finishing processes like scouring, bleaching, hot and cold washing, and drying were done accordingly.

Physical Properties of the Fabrics

The ends per centimetre and picks per centimetre of all fabric samples were measured following the ASTM D 3775-12 standard testing method.³⁰ Fabric thickness was measured by the ASTM D 1777-96.³¹ The areal density of the fabric (g/m²) was measured using the ASTM D 3776-09 standard. To ensure precision, an average of five readings was recorded for each fabric sample.³²

Evaluation of Low Stress Mechanical Properties of the Fabric

The Kawabata Evaluation System measured the fabric’s bending, compression, surface, tensile, and shear properties using specific instruments (KESF B1, KESF B2, KES B3, KESF B4) as shown in Figure 4. The sample size was maintained at 20 cm × 20 cm as per standard. The samples were tested with 10 readings in the warp and weft directions. Details on the parameters and their units are provided in Table 2.

Figure 4.

Principle of Kawabata Evaluation Systems for Nomex fabric (low-stress mechanical properties).

Table 2.

Properties evaluated by Kawabata Evaluation System.³³

Tensile	EM	Extensibility	%
	LT	Linearity of tensile curve	–
	WT	Tensile energy	gf cm/cm²
	RT	Tensile resilience	%
Shearing	G	Shear rigidity	gf/cm degree
	2HG	0.5° shear angle hysteresis	gf/cm
	2HG5	5° shear angle hysteresis	gf/cm
Bending	B	Bending rigidity	gf cm²/cm
Bending	2HB	Bending moment hysteresis	gf cm/cm
Compression	LC	Compression-thickness curve linearity	–
	WC	Compressional energy	gf cm/cm²
	RC	Compressional resilience	%
Surface	MIU	Coefficient of friction	–
	MMD	Mean deviation of MIU	–
	SMD	Geometrical roughness	µm
Construction	W	Weight per unit area	mg/cm²
Construction	T	Fabric thickness	mm

Linearity of the Load Extension Curve

The linearity of the load extension curve is commonly defined from the tensile force–strain curve (Figure 5).¹⁴ If the area under the load–strain curve is WT (Nm/m²) and the area of the triangular OAB is WOT then the linearity LT is expressed as follows equation (1):³⁴

LT = \frac{WT}{WOT}

(1)

Figure 5.

Linearity of tensile force–strain curve (LT).

Tensile Energy

The tensile energy (Nm/m²), is defined as the area under the tensile force–strain curve (Figure 5), WT, which is the energy required to extend a fabric by removing the applied tensile stress.³⁵

Tensile Resilience

The tensile resilience, RT (percentage), denotes the fraction of energy recovery from tensile deformation. The garment aesthetics are also affected by tensile resilience. Reduced values represent softer fabrics, whilst elevated values enhance elasticity and stability. As tensile strain grows, resilience reduces, affecting the garment’s ability to recover to its original shape.³⁶

Extensibility

The extensibility, EM (percentage), quantifies the deformation of a fabric under maximum force, whereas the fabric tensile extensibility measures the degree of elongation shown when subjected to a load.³⁷

Shear Rigidity

The shear rigidity, G (gf/cm·degree) defines a fabric’s resistance to shear deformation, influencing its rigidity, flexibility, and drapability. It is affected by the frictional properties of warp and weft yarns, their bending stiffness, and the density of intersections per unit area.³⁸

Shear Hysteresis

The shear hysteresis in fabric denotes the energy dissipated during a shear deformation cycle, attributed to friction and structural alterations and associated with handle attributes. Shear hysteresis also refers to the recovery from shear stress.³⁹

Bending rigidity

The bending property is a critical component of a fabric’s drape performance. The fabric’s flexibility is determined by its bending rigidity.⁴⁰

Bending Hysteresis

The bending hysteresis refers to the energy loss that occurs during a bending cycle when a fabric is bent and subsequently allowed to return to its original form. This difference in bending moment between loading and unloading curves influences the fabric’s resistance to applied loads.⁴¹

Compression Energy

The energy required to deform a fabric during compression is known as compression energy or WC (gf cm/cm²). It measures the fabric’s compressibility and correlates with its thickness and other fabric parameters such as weave or knit structure and compactness.⁴²

Compression Resilience

The compression resilience, RC (percentage), is a mechanical property of fabrics, affecting their ability to return to their original shape after external force is removed. It is closely related to fabric handle, softness, and fullness, with higher RC values resulting in more springy and better hand performance.⁴³

Results and Discussion

Low Stress Mechanical Properties of Fabric

The objective measurement of fabric mechanical properties has enormous potential for quality control of clothing materials. Low-stress mechanical properties significantly impact the evaluation of the appropriate handle properties of a specific fabric. To evaluate sensorial comfort and develop an appropriate fabric structure, fabric finishing and apparel design depend on the fabric’s tensile, shear, compression, and other surface properties.^44,45

Tensile Properties

The low-stress tensile properties of fabrics include tensile energy, linearity of the load–extension curve, fabric extensibility, and tensile resilience. A strong correlation was identified between fabric hand value and tensile properties, with R² values of 0.79, 0.94, and 0.83 for plain, basket, and ripstop weaves, respectively. Enhanced fabric handle was associated with increased linearity in the load–extension curves.

In Figure 6, it can be observed that increasing the PPC from 15.7 to 20.5 significantly improved the LT value for all weave structures. When the pick density increases, it refers to the amount of yarn increase in the same area, and finally, as the areal density increased, the tensile linearity also improved. For the plain weave, the LT increased from 0.38 at 15.7 PPC to 0.58 at 20.5 PPC. The basket weave showed an LT increase from 0.42 to 0.59, while the ripstop weave’s LT rose from 0.40 to 0.56. For the plain weave structure, the linearity showed a maximum increment rate of 53% due to the highest interlacing points existing in this structure compared to the basket and ripstop structures, where the increment rate was 40.4% and 40% respectively with relation to the pick density. These results highlight the relation between higher PPC and enhanced fabric stiffness and linearity under tensile stress.

Figure 6.

Effect of thread density and woven structure on the linearity of the load extension curve (LT).

In Figure 7, it can be seen that the WT values (gf cm/cm²) were highest at the lowest weft density (PPC) of 15.7 for plain and basket weaves. For the plain weave, the WT was 3.55 gf cm/cm² at 15.7 PPC, increasing to 7.3 gf cm/cm² at 20.5 PPC. Similarly, the basket weave showed WT values of 3.32 gf cm/cm² at 15.7 PPC and 6.55 gf cm/cm² at 20.5 PPC. In contrast, the ripstop weave displayed a different pattern, with the lowest WT at 15.7 PPC and increasing to 4.22 gf cm/cm² at 18.1 PPC before declining to 3.55 gf cm/cm² at 20.5 PPC. These results suggest that a higher PPC generally increases tensile energy in plain and basket weaves, while ripstop weaves exhibit a more variable response. The plain weave structure consists of the highest interlacing points, and it further increases with an increase in pick density. The tensile energy increased by 100% for 15.7–20.5 PPC of the plain weave. The basket weave structure, which is a derivative of the plain weave, exhibited a similar trend with an increment of around 97% for 18.1 and 20.5 PPC. The reason for this is the rising number of yarns with increasing pick density. It is known that a higher number of yarns will show a higher tensile energy. In the ripstop weave structure, the tensile energy increased by 28% for 15.7–18.1 PPC and decreased by around 16%. This may be due to having four different weave structures in the repeat of the ripstop design. This makes the structure increase the breaking energy up to a certain pick density, later decreasing following a trend of plain and basket design. This highlights how the weave structure and weft density significantly influence the fabric energy absorption characteristics.

Figure 7.

Effect of thread density and woven structure on the tensile energy of the load–extension curve (WT).

Figure 8 demonstrates that increasing the PPC from 15.7 to 20.5 significantly enhanced the RT across all weave structures. In the plain weave, RT increased from 46.1% at 15.7 PPC to 56.27% at 20.5 PPC, indicating improved fabric elasticity with higher PPC. Similarly, the basket weave showed a rise in RT from 53.99% to 57.47%, suggesting better resilience as the weft density of the structure. The ripstop weave exhibited the most substantial improvement, with RT increasing from 33.58% at 15.7 PPC to 55.33% at 20.5 PPC. Among all three types of fabrics, the ripstop structure exhibits softer attribute due to lower tensile resilience RT% at 15.7 PPC than the others. Moreover, the tensile resilience of the ripstop design increases by 65% which is the highest increase rate compared to the other designs which means that it becomes more elastic and stiffer rapidly with increasing pick density. These findings suggest that higher PPC enhances the tensile resilience of woven fabrics, making them more resistant to deformation under stress.

Figure 8.

Effect of thread density and woven structure on the tensile resilience of load extension (RT).

Shear and Bending Properties

Shear force is applied using the Kawabata Evaluation system (KESF-B1) to measure the shear properties of a fabric. Bending rigidity reflects the resistance of the fabric to bending deformation. In experimental evaluations like the KES, it is determined by calculating the average slope of the bending curve between curvatures of ±0.5 and ±1.5 cm⁻¹. Bending hysteresis, on the other hand, is measured by the vertical distance between the forward and recovery curves at a curvature of 1.0⁻¹.

In Figures 9 and 10, it is shown that the shear rigidity and bending rigidity increase with increased pick density of all woven structures. The shear rigidity values for basket design are seen at their lowest (0.27–0.38 gf/cm deg) compared with the plain and ripstop design. The reason for this is that the basket design has the maximum number of floats which decreases the shear rigidity.⁴⁶ Conversely, the bending rigidity of the fabrics was not significantly influenced by the float percentage of the weave design but was primarily controlled by the pick density. For this reason, the bending rigidity increase rates for all designs were nearly same at around 70% with a range of values from 0.04 to 0.09 gf cm²/cm.

Figure 9.

Effect of thread density and woven structure on the shear rigidity of the fabric.

Figure 10.

Effect of thread density and woven structure on the bending rigidity of the bending deformation curve (B).

Relation Between Bending Rigidity and Bending Hysteresis

The bending hysteresis decreases as the linear density of the different woven structures increases. It shows that increasing the PPC from 15.7 to 20.5 significantly enhances all of the weave structures’ bending rigidity (B). Specifically, B increased from 0.04 gf cm²/cm at 15.7 PPC for the plain weave to 0.07 gf cm²/cm at 20.5 PPC. The basket weave exhibited a similar trend, with bending rigidity rising from 0.05 to 0.08 gf cm²/cm, while the ripstop weave’s rigidity increased from 0.05 to 0.09 gf cm²/cm. Additionally, the bending hysteresis increased with the rise in pick density. These findings suggest that a higher PPC improves the fabric’s resistance to bending and increases its bending hysteresis.

Figure 11 depicts the relationship between bending hysteresis and bending rigidity across various weave designs. The ripstop weave demonstrates the highest bending hysteresis values, ranging from 0.1 to 0.19 gf cm/cm. In contrast, the basket weave exhibits the lowest hysteresis values, between 0.09 and 0.11 gf cm/cm, while the plain weave falls in between. The increased hysteresis in ripstop weaves is attributed to their diverse interlacing fields, whereas the basket weave’s lower hysteresis indicates superior resistance to applied forces compared to plain and ripstop designs.

Figure 11.

Relation between bending hysteresis 2HB and bending rigidity B.

Figure 12 shows the correlation between 2HG and G across the same weave structures. Similar to the bending properties, the basket weave records the lowest shear hysteresis values (0.88–1.31 gf/cm), while the ripstop design has the highest (1.49–4.68 gf/cm). The plain weave again exhibits moderate values. The higher 2HG observed in the ripstop weave is similarly linked to its multiple interlacing fields, highlighting a consistent pattern between the bending and shear behaviours.

Figure 12.

Relation between shear hysteresis 2HG and shear rigidity G.

G is the resistance offered by the fabric against the shear deformation. It is mainly influenced by the resistance to mobility offered at the cross-over points between intersecting yarns.

Figure 13 depicts the G and 2HG5 (at a 5° shear angle) for all the weave structures. The trend for all the samples remains nearly same as for the 0.5° shear angle. The only difference is observed in increased average values of shear hysteresis, for instance about 12% for basket, 23% for plain, and 48% for ripstop designs.

Figure 13.

Relation between shear hysteresis 2HG5 and shear rigidity G.

Surface Characteristics

The surface properties play an important role in the handle of the fabrics. The geometrical roughness measures the surface texture of a fabric, which is never perfectly smooth. The sensor only detects geometrical ups and downs, not surface fibre orientation. Higher values of SMD indicate more surface unevenness, while lower values indicate smoother, even surface.^7,47 The SMD decreases as the weft density of different woven structures increases.

Figure 14 further illustrates that increasing the PPC from 15.7 to 20.5 significantly reduces the roughness across all weave structures. For the plain weave, the SMD decreased from 10.39 µm at 15.7 PPC to 8.81 µm at 20.5 PPC. The basket weave exhibited a decrease in SMD from 13.65 µm to 12.2 µm, while the ripstop weave’s SMD decreased from 12.34 µm to 9.46 µm. These findings indicate that a higher PPC leads to a smoother fabric surface, reducing the geometrical roughness. Moreover, the basket and ripstop designs contain float yarns in the design with higher geometrical roughness values, which positively corelate with the previous study where float yarn increased the surface roughness.⁴⁸ The consistent reduction in SMD across different weaves highlights the importance of PPC in achieving smooth fabric textures.

Figure 14.

Effect of thread density and woven structure on geometrical roughness (SMD) of different weave structures.

Compressional Characteristics

The compressibility of fabric is measured by calculating the percentage change in thickness when the compressive stress on the fabric is increased from 0.5 to 50 gf/cm².⁴⁹

Figure 15 shows that increasing the PPC from 15.7 to 18.1 initially reduced the linearity of the compressional LC for all weave structures, but it increases again at 20.5 PPC. The LC decreased from 0.22 at 15.7 PPC to 0.25 at 18.1 PPC for the plain weave, then returned to 0.25 at 20.5 PPC. The basket weave had an LC of 0.23 at both 15.7 and 20.5 PPC, with a decrease at 18.1 PPC. The ripstop weave’s LC decreased from 0.33 to 0.28 at 18.1 PPC, then increased to 0.32 at 20.5 PPC. These patterns indicate that while the LC generally declines with increasing PPC, it can rise again at higher PPC levels, reflecting complex changes in compressional properties with weave density.

Figure 15.

Compression–thickness curve linearity (LC) of different woven structures.

Figure 16 illustrates that increasing the PPC from 15.7 to 20.5 significantly enhances compressional resilience across all weave structures. For the plain weave, the RC improved from 32.25% at 15.7 PPC to 42.42% at 20.5 PPC, demonstrating a notable increase in compressional resilience with higher PPC. Similarly, the basket weave showed an increase in RC from 35.9% to 40.5% as PPC increased, indicating improved resilience with greater weft density. The ripstop weave displayed the most considerable improvement, with RC rising from 18.9% at 15.7 PPC to 32.37% at 20.5 PPC. These results suggest that a higher PPC generally contributes to better compressional resilience in woven fabrics, because the pick density of a fabric is directly proportional to compressional resilience. The number of fibres (aramid) in a particular area of a fabric increases with the increase in pick density and the higher number of fibres creates more bulkiness of the material that positively correlates with the compressional resilience of the aramid fibres.⁵⁰

Figure 16.

Compression resilience (RC) of different woven structures.

Figure 17 shows that the WC (gf cm/cm²) was lowest at the lowest PPC of 15.7 for all weave structures. For the plain weave, the WC increased from 0.28 gf cm/cm² at 15.7 PPC to 0.39 gf cm/cm² at 20.5 PPC. The basket weave exhibited a similar trend, with the WC rising from 0.46 gf cm/cm² at 15.7 PPC to 0.51 gf cm/cm² at 20.5 PPC. The ripstop weave followed the same pattern, with the highest WC of 0.89 gf cm/cm² at 20.5 PPC and the lowest of 0.69 gf cm/cm² at 15.7 PPC. These results indicate that a higher PPC generally uplifts compressional energy across different weave structures. The compressional energy of fabric is increased due to the increased bulkiness with greater pick density.

Figure 17.

Compression energy (WC) of different woven structures.

Comparative Analysis of Different Properties

Table 3 shows that the plain weave structures have the lowest LT values, ranging from 0.38 to 0.58, and the highest compressional energy from 3.55 to 7.3 gf cm/cm², with RT increasing from 46.1% to 56.27%. It also shows the highest compression resistance, RC, from 32.25% to 42.42% and flexibility, with a bending rigidity between 0.04 and 0.07 gf cm²/cm. Basket weave fabrics have slightly higher LT (0.42–0.59) and tensile resilience (53.99%–57.47%), with tensile energy varying from 3.32 to 6.55 gf cm/cm² and bending rigidity ranging from 0.05 to 0.08 gf cm²/cm. Compression resilience is similar (35.99–40.51%) but slightly lower than for the plain weave. The ripstop weave starts with the lowest LT (0.4) and tensile resilience (33.58%) but increases to 0.56% and 55.33%, respectively, with tensile energy remaining consistent (3.1–3.55 gf cm/cm²). Ripstop fabrics have the lowest compression resilience (18.96–32.37%) and bending rigidity (0.05–0.09 gf cm²/cm), but they excel in tensile strength and load-bearing capacity, while showing the greatest decrease in surface friction (12.34–9.46 µm). Overall, the plain weave offers the best flexibility and compression resistance because of its lowest areal density and maximum yarn interlacement, the basket weave balances strength and flexibility due to its moderate areal density, and the ripstop weave excels in tensile strength and load-bearing due to the rib effect in the structure but lacks compressional resilience and flexibility.

Table 3.

Comparative values of various properties of plain basket and ripstop weave structures at different weft densities.

Weave	Fabric code	LT	WT	RT	B	2HB	2HG	2HG5	SMD	LC	WC	RC
Plain	PL1	0.38	3.55	46.1	0.04	0.09	0.89	1.14	10.39	0.22	0.28	32.25
	PL2	0.43	4.95	53.21	0.06	0.1	1.89	2.27	10.16	0.11	0.37	41.45
	PL3	0.58	7.3	56.27	0.07	0.11	2.41	2.96	8.81	0.25	0.39	42.42
Basket	BS1	0.42	3.32	53.99	0.05	0.07	0.88	1.01	13.65	0.23	0.46	35.99
	BS2	0.54	6.55	56.12	0.07	0.09	1.26	1.4	12.09	0.15	0.49	39.31
	BS3	0.59	6.55	57.47	0.08	0.11	1.31	1.51	12.2	0.23	0.51	40.51
Ripstop	RS1	0.4	3.1	33.58	0.05	0.1	1.49	3.26	12.34	0.33	0.69	18.96
	RS2	0.52	4.22	45.83	0.07	0.13	2.58	4.67	12.63	0.28	0.75	25.8
	RS3	0.56	3.55	55.33	0.09	0.19	4.68	5.06	9.46	0.32	0.89	32.37

Conclusions

This study explored the low-stress mechanical properties of Nomex-based station wear fabrics by examining the effects of varying weft density (PPC) across plain, basket, and ripstop weave structures. Results indicated a consistent trend where increasing the PPC from 15.7 to 20.5 enhanced mechanical performance across all weaves, notably improving the linearity of the load–extension curve. The tensile energy increased significantly for plain (3.55–7.3 gf cm/cm²) and basket (3.32–6.55 gf cm/cm²) weaves, while the ripstop design peaked at 18.1 PPC. Shear rigidity and bending rigidity also rose with PPC, the latter ranging from 0.04 to 0.09 gf cm²/cm. Ripstop weaves showed the highest bending hysteresis (0.1–0.19 gf cm/cm), contrasting with basket weaves (0.09–0.11 gf cm/cm). Surface roughness declined and compressional energy increased with PPC, with compressional resilience improving from 32.25% to 42.42% for plain, from 35.9% to 40.5% for basket, and from 18.9% to 32.37% for ripstop weaves. These results reflect a clear trend of enhanced mechanical performance with increased weft density, yet the study’s scope is limited by its focus on single-layered fabrics due to KESF thickness constraints, the exclusion of other weave types and yarn densities, and a lack of consideration for long-term wear, environmental, or thermal factors. Future research should integrate multilayer evaluations, broader fabric designs, and detailed geometrical analyses to generalize findings. Despite these limitations, the study provides valuable insights for the development of high-performance, comfort-optimized protective fabrics, with implications for improved safety, functional design, and material selection in fire and industrial protective wear, emergency response, military and technical textile applications for extreme environments.

Footnotes

ORCID iDs

Rochak Rathour

Md. Jawad Ibn Amin

Md. Azharul Islam

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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Analysis of the low-stress mechanical properties of station wear uniforms of firefighters

Abstract

Keywords

Introduction

Materials and Methods

Materials

Methodology

Sample Preparation for Measuring the Hand Value

Physical Properties of the Fabrics

Evaluation of Low Stress Mechanical Properties of the Fabric

Linearity of the Load Extension Curve

Tensile Energy

Tensile Resilience

Extensibility

Shear Rigidity

Shear Hysteresis

Bending rigidity

Bending Hysteresis

Compression Energy

Compression Resilience

Results and Discussion

Low Stress Mechanical Properties of Fabric

Tensile Properties

Shear and Bending Properties

Relation Between Bending Rigidity and Bending Hysteresis

Surface Characteristics

Compressional Characteristics

Comparative Analysis of Different Properties

Conclusions

Footnotes

ORCID iDs

Funding

Declaration of conflicting interests

References