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Assessment of Effectivity of ‘Bio-Quart and Bit- Guard Finish’ with Very Low Concentration of Cross-Linking Agent for Surgical Gown Application

Abstract: The objective of this study was to investigate the effectivity of Bio-Quart and Bit-Guard with very low concentration of cross-linking agent. Commercially available cotton plain woven fabric with 105 GSM, twill woven with 190 GSM and polyester-cotton with 95 GSM was used. Water repellent, antibacterial and cross-linking agent was used in a single bath using pad-dry-cure method. Liquid barrier properties of samples were analyzed by water impact penetration and hydrostatic pressure test. The physical properties of samples were analyzed by tensile and tearing strength. Water vapor transmission of samples was also analyzed to measure comforts.

Low Concentration of Cross-Linking Agent for Surgical Gown Application
Assessment of Effectivity of ‘Bio-Quart and Bit-Guard Finish’ with Very Low Concentration of Cross-Linking Agent for Surgical Gown Application

 

It was observed that for impact penetration test cotton sample with 105 GSM and cotton-polyester sample with 95 GSM showed protection level II according to Association for the Advancement of Medical Instrumentation (AAMI) but in hydrostatic pressure test, level was I. It is confirmed that the used finishing concentration was not sufficient to improve barrier effectivity. Concentration of water repellent and cross-linking agent are need to be increased to get highest level of protection.

Keywords:  Bio-Quart; Bit Guard; Cross linker; Water repellency; Air permeability.

Introduction

Surgical gown used by frontline medical staff as protective clothing in the operation theater to prevent the spread of bacteria or any other micro-organism from patients to surgical staff or vice versa. All human blood and other body fluids are treated as infection to human health, act as a carrier and transport the bacteria through the fabric (Huang W and Leonas K.). Surgical gown does a dual function of preventing transfer of microorganism and body fluids to prevent cross infection (CDC 1998; Huang & Leonas 2000; Laufman et al. 1979; Slater 1998). Association for The Advancement of Medical Instrumentation (AAMI) have made recommendations on how to protect surgical staff as well as patients from exposure to blood borne pathogens and bacteria (AAMI 2003; Slater 1998). AAMI standard, PB70:2003 provides four classification levels for barrier performance of surgical gowns established four levels of protection on the basis of four tests, i.e. spray impact penetration, hydrostatic head, blood repellency, and antibacterial activity tests.

Table 1: List of Test Parameters with Recommended Values

Sl. Test Parameter Unit Minimum/Maximum Requirement (as per AAMI Standards) Remarks
Level 1

(minimal)

Level 2

(low)

Level 3

(moderate)

Level 4

(high)

1. Tensile Strength (ASTM D5034, ASTM D1682) N >30 >60 >100 >250 a For isolation gown Levels (1,2,3,4) ≥30N
2. Tear resistance (ASTM D5587(woven), ASTM D5587 (nonwoven), ASTM D1424) N >5 >10 >50 >100  a For isolation gown Levels (1,2,3,4) ≥10N
3. Seam Strength (ASTM D751 (stretch woven or knit)) N ≥30 ≥30 ≥30 ≥30 ASTM F3352-19

Ref: ASTM D1683/D1683M

4. Water vapor transmission (breathability) (ISO 11092:2014(EN); ASTM F1868 Part B, ASTM D6701 (nonwoven), ASTM D737-75; or equivalent (ASTM E96/E96M-16*)) m2Pa/W <30 (for coveralls) <30 (for coveralls) ISO11092:2014(EN)
mm/s AP>100 5<AP<100 AP≤5 ASTM D737-75

Re: EN14058:2017(E)

5. Water Resistance: Hydrostatic Test (AATCC 127; BS EN 13795:2019) cm H2O N/A >20 >50 (sterile) >100 (sterile) No data available for Level 1
>57.3 (fluid resistant) >91 (fluid resistant)
6. Water Resistance: Impact Penetration Test (AATCC 42 or equivalent (e.g., AATCC 35*)) g <=4.5 <=1 <=1 <=1 No data available for Level 4. Emphasis given on breathability test
7. Synthetic Blood Penetration Test (ASTM F1670 or equivalent) * Pass at Psi/Kpa N/A N/A N/A No penetration at 2 psi up to 1 hour  * PPE importers must present relevant documents and certification
8. Viral Penetration Test (ASTM F1671 or equivalent) * Pass at Psi/Kpa N/A N/A N/A No penetration at 2 psi up to 1 hour

 

The above parameters were developed based on the WHO (World Health Organization) specifications on the basis of AAMI standard.

The reusable surgical gown provides more comfort than disposable surgical gown because of larger pore size of the fabric provides better water vapor transmission. They lose durability and barrier protection after repeated washing (Laufman et al. 1975). Several researchers showed that water repellency and antibacterial resistance can be improved by applying water repellent and antibacterial finishes to the fabric sample (Brock et al. 1994; Garibaldi et al. 1986; Gupta 1998; Laufman et al. 1975).

 

The optimum concentration of the fluorochemical for synthetic blood repellency is 5% owf. (Jeong-sook cho, Gilsoo-cho 1997). 4% of fluorochemicals and 2% antibacterial finish creates level II protection for woven surgical gown (Midha et al, 2014). Spunbond/meltblown/spunbond fabric samples with 4% and 7% fluorochemical finish and 1.5% antibacterial finish can provide level 4 protection. Spunbond fabrics require 4% and spunbond/meltblown/ spunbond fabrics require 1% fluorochemical finish to achieve level 2 protection (Vinay Kumar Midha, Arjun Dakuri and Varsha Midha 2012). Fluorocarbon-based finishes are most effective water repellent agent to reducing the surface energy of the fabric sufficiently to repel both water and oil-based liquids.

 

In this study justification of effectiveness of the chemicals (Bio-Quart and Bit-Guard and cross-linking agent) was done with very low concentration. With minimum concentration level we could minimize the cost and develop an effective fabric to reduce microbe as well as get higher repellence to get blood resistance for surgical gown application.

Experiment:

  1. Materials
 

Samples

 

 

     Fibre composition Fabric weight (g/m2) Weave Warp density (ends/cm) Weft

density

(picks/cm)

Warp

linear

density

(Ne)

Weft

linear

density

(Ne)

A 65/35 PC* 90 Plain 110 76 45 45
B 100% cotton 105 Plain 108 76 40 40
C 100% cotton 190 2/1 twill 122 72 30 20

Characteristics of fabric samples

*Note: PC- Polyester cotton blend.

  1. Chemicals

In this study fluoropolymer ‘Bit Guard FC-3000N’ as water repellent agent, ‘Bio-Qaurt 200’ is used as antibacterial agent, and SU-268A as a cross linking agent is used. All chemicals are sourced form Dysin-Chem Limited, Bangladesh.

  1. Methods

To finish the fabric samples pad-dry-cure method was used. All three types samples were pre-treated.

The antibacterial and water repellent finish were mixed in a same bath at add on levels of 2%, 5% and 0.3% of weight of fabric. All the chemicals were added slowly in hot water bath. The fabric samples were immersed in the solution for approximately 4 to 5 sec and padded through squeezed roller to ensure 85% pic-up. Each sample were padded twice to ensure better pic-up. After padding the fabrics were dried in laboratory woven at 1000   C for 3 to 4 min and then cured at 1500   C for 2 min.

After finishing fabric samples were tested for water repellency, Water vapor transmission (breathability), tensile and tearing strength.

Impact penetration test is performed according to AATCC test method 42. Hydrostatic pressure was performed according to AATCC 127. Tensile strength was performed according to ASTM D5034. Tear resistance was performed according to ASTM D5587. Water vapor transmission was performed according to ASTM D737-75. All testing was performed three times and the mean value was taken.

 

Results

Water Resistance Testing:

  • Impact Penetration Test
Sample Resistant value (g)
A 0.20
B 0.98
C 1.65

 

Water impact penetration was measured according to AATCC 42. In this test sample A (P/C 90 GSM) and sample B (cotton 105 GSM) passed AAMI protection Level II.

 

  • Hydrostatic Pressure Test

 

Samples
A 17.44
B 18.73
C 6.73

 

 

Water resistance was measured according to AATCC 127. In this test all samples show AAMI level I. It is clear that the used concentration is not enough to make level II protection.

In impact penetration taste, sample A and B proofs that, the chemicals are improving water repellency for Cotton and PET. Although, Sample C (100% cotton, 190 GSM) has the most compact structure than two other samples, hence resistance value should be higher but chemicals did not distributed evenly on the fabric surface and pores. Again, the poorest resistant value of C in Hydrostatic pressure proofs insufficient chemical distribution, Therefore, increasing immersing time and chemical concentration will increase required water repellency.

  • Tensile Strength Test
Samples MD value CD value
A 451.37 N 253.7 N
B 405.6 N 192.07 N
C 564.27 N 254.53 N

 

The tensile strength was measured according to ASTM D5034 method. Tensile strength of the samples was measured in both machine direction (MD) and cross-direction (CD). The tensile strength of the samples in MD direction is greater than CD direction.  All three samples have required strength to be used up to level III gown according to WHO’s specification.

It is imperative that surgical textile fabric is required to be strong enough to withstand stress during usage. Specifically, certain areas of the body are subject to stress and pressure, resulting in peel-off.

  • Tear Resistance Test
Samples MD value CD value
A 61.51 53.43
B 41.29 19.55
C 92.66 66.12

Tear resistance was measured according to ASTM D5587. Tear resistance was also measured in both machine direction (MD) and cross-direction (CD). The tensile strength of the samples in MD direction is greater than CD direction. Here, sample A and C have required strength to be used up to level III gown and B to be used in level II gown according to WHO’s specification.

Here sample A and C shows greater tear resistance than B. Sample A having 65% PET, shows higher resistance and sample C having higher GSM (190) and twill structure shows height resistance and sample B having low GSM (105) shows lowest resistance. Further increase in flucochemicls concentration will increase the resistance too.

 

(V)          Water Vapor Transmission (breathability)

Samples Values (mm/s)
A 1186
B 944.8
C 1304

Water vapor transmission rate was measured by ASTM D737-75. It is observed that the transmission rate shows higher comfort than usual requirements. Here sample C is has more compact and high GSM but shows maximum vapor transmission that indicates the insufficient and irregular finishing.

Conclusion

In this study pretreated 100% cotton and cotton/poly blend samples were used to apply antibacterial and water repellent finish with very little amount of cross-linking agents and the finish fabric were tested for evaluation of water repellency and physical properties to be used in surgical gown. Most importantly the materials were immersed for approximately 4 to 5 sec and padded twice. It is observed that all the samples provide the required physical property for level III surgical gown according to WHO’s suggestion. Sample A and B provides AAMI level 2 protection at impact penetration but did not provide hydrostatic resistance to this level. The 190 GSM cotton twill sample has the compact structure than two others, hence should provide better water repellency but the hydrostatic pressure was two times lower than two other (100% cotton and cotton/PET) samples. So, it is confirmed that the use concentration of chemicals and padding process was not effective to create AAMI level II protective gown. It is advised to increase material immersing time and cross-linking agent’s concentration to 1 to 1.5% to get AAMI level II protection by this chemicals and fabric construction.

Acknowledgement

The author is grateful to Textile Today for organizing Textile Talent Hunt Project and providing financial support and factory engagement. He is also thankful to Dysin-Chem Limited, Bangladesh for providing all chemicals and lab facility

If anyone has any feedback or input regarding the published news, please contact: info@textiletoday.com.bd

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