Understanding SMS, SMMS, and PP+PE in PPE Non-Woven Fabrics

Non-woven fabrics have become essential materials in personal protective equipment (PPE), especially in medical and healthcare settings. Among the various types, SMS, SMMS, and PP+PE are prominent constructions, each with distinct characteristics and applications. This guide explores their meanings, differences, and appropriate uses in PPE products.

SMS Non-Woven Fabric

Meaning: SMS stands for Spunbond-Meltblown-Spunbond, representing a three-layer composite non-woven fabric structure . It consists of:

• Two outer layers of spunbond polypropylene (S)
• One middle layer of meltblown polypropylene (M)

Key Characteristics:

• Lightweight yet durable with good transverse and longitudinal strength
• Breathable while providing water resistance
• Effective filtration from the meltblown middle layer
• Comfortable for wearers due to soft texture
• Chemical resistant to various substances including heat and moisture

Medical Applications:

• Surgical face masks
• Isolation gowns
• Surgical drapes
• Single-use caps and shoe covers
• Bed linens and lab coats

The spunbond layers provide strength and durability, while the meltblown middle layer acts as the primary filtration barrier against particulates, bacteria, and fluids . SMS fabrics can be further enhanced with chemical additives to become anti-static, flame retardant, or fluid-repellent (water, alcohol, etc.) .

SMMS Non-Woven Fabric

Meaning: SMMS represents Spunbond-Meltblown-Meltblown-Spunbond, a four-layer variation of SMS with double meltblown layers .

Key Differences from SMS:

• Contains two meltblown layers instead of one, sandwiched between spunbond layers
• Offers higher filtration efficiency due to additional meltblown material
• Provides enhanced barrier properties against liquids and microorganisms
• More symmetrical structure with improved durability
• Better water repellency and bacterial resistance compared to SMS

Why Choose SMMS Over SMS? SMMS is particularly valuable in situations requiring:

• Higher protection levels against pathogens and fluids
• Enhanced filtration performance
• More durable protective barriers
• Superior liquid repellency for surgical and isolation applications

Medical Applications:

• High-level isolation gowns
• Reinforced surgical gowns
• Protective coveralls for infectious disease control
• Advanced filtration materials for medical masks

The additional meltblown layer in SMMS significantly improves its performance as a microbial and fluid barrier while maintaining breathability .

PP+PE Non-Woven Fabric

Meaning: PP+PE refers to a composite material combining:

• Polypropylene (PP) non-woven fabric
• Polyethylene (PE) film or coating

Key Characteristics:

• Waterproof properties from the PE component
• Hydrophilic surface when combined with absorbent materials like viscose
• Cost-effective protection solution
• Good strength from the PP base

Structure Variations:

1. PP non-woven with PE coating: Creates a one-sided waterproof barrier
2. PP non-woven laminated with PE film: Provides complete waterproofing
3. PP non-woven + absorbent material (viscose) + PE: Creates a dual-function material that absorbs on one side and repels on the other

Medical Applications:

• Waterproof medical bed sheets
• Surgical drapes requiring fluid control
• Hospital mattress protectors
• Patient gowns needing liquid protection

The PE component provides the waterproof barrier, while the PP non-woven offers strength and breathability. When combined with absorbent materials like viscose, one side can absorb patient fluids while the PE side protects underlying surfaces .

Comparative Analysis of SMS, SMMS, and PP+PE

Feature	SMS	SMMS	PP+PE
Layers	3 (S-M-S)	4 (S-M-M-S)	2+ (PP+PE)
Filtration	Moderate	High	Low
Breathability	High	Moderate	Low-Moderate
Water Resistance	Good	Excellent	Excellent
Primary Use	General medical PPE	High-protection PPE	Waterproof medical textiles
Cost	Moderate	Higher	Lower
Flexibility	High	Moderate	Variable

Selection Guidelines for PPE Applications

When to choose SMS:

• For general medical procedures requiring basic protection
• When balance between protection and breathability is needed
• For disposable products where cost is a consideration
• Applications needing comfort during extended wear

When to choose SMMS:

• For high-risk procedures with exposure to bodily fluids
• When higher bacterial filtration is required
• For isolation scenarios in infectious disease control
• Surgical applications demanding superior liquid barrier properties

When to choose PP+PE:

• For waterproof bed linens and mattress protection
• When one-sided fluid absorption is needed (with viscose combo)
• For cost-sensitive applications requiring liquid protection
• Non-critical medical textiles where filtration isn’t primary

Advanced Variations and Combinations

Manufacturers have developed more complex structures combining these technologies:

1. SSMMS: Spunbond-Spunbond-Meltblown-Meltblown-Spunbond (5 layers) for ultra-high filtration
2. SMS+PE: Combines SMS filtration with PE waterproofing for enhanced protection
3. SMMS with special treatments: Can include anti-static, alcohol-repellent, or blood-repellent properties
4. Hydrophilic PP+PE: Modified versions for specialized absorption needs

These advanced materials allow for precise engineering of protective properties to meet specific medical and industrial requirements .

Manufacturing Processes

SMS/SMMS Production:

1. Spunbond layer creation: Melted polymer extruded through spinnerets to form long filaments
2. Meltblown layer creation: Melted polymer transformed into fine fibers for filtration
3. Thermo-bonding: Layers combined using heat and pressure with embossed rollers
4. Special treatments: Additional coatings or treatments applied as needed

PP+PE Production:

1. PP non-woven production: Through spunbond or other non-woven processes
2. PE application: Either as coating or laminated film
3. Bonding: Through thermal or adhesive methods

Performance Standards and Testing

These materials undergo rigorous testing for medical use:

1. Tensile strength (ASTM D5034)
2. Hydrostatic head (ISO 811) for liquid resistance
3. Air permeability (ASTM D737)
4. Filtration efficiency (various standards)
5. Barrier performance against bacteria and fluids

For surgical gowns and drapes, materials are rated according to AAMI PB70:2012 standards with four levels of protection based on liquid barrier capabilities .

Environmental and Usage Considerations

1. Disposability: All three types are generally single-use to prevent cross-contamination
2. Sterilization: Compatible with ethylene oxide and other sterilization methods
3. Environmental impact: PP-based materials can be incinerated after use
4. Biodegradability: Standard versions are not biodegradable, but special formulations exist

Future Developments

The non-woven PPE market continues to evolve with:

• Thinner yet more protective materials
• Enhanced breathability without compromising barrier properties
• Sustainable alternatives with maintained performance
• Smart materials with sensing capabilities
• Improved comfort for extended wear situations

Understanding the differences between SMS, SMMS, and PP+PE non-woven fabrics enables healthcare providers and PPE purchasers to make informed decisions based on specific protection needs, comfort requirements, and budget considerations. Each material offers unique advantages that make it suitable for particular applications in the medical and protective equipment fields.