Understanding Sneaker Midsole Materials: A Concise Guide

Sneaker Structure and Midsole Classification

Basic Structural Functions

• Upper: Provides support, containment, and breathability

• Midsole: Determines cushioning, responsiveness, and comfort

• Outsole: Responsible for traction and durability, directly contacting the ground

Midsole Material Categories

Divided by physical structure into two main types:

(I) Mechanical Structures

Utilizes rubber, plastic, carbon fiber through and layered designs to absorb impact through deformation.

Representative Technologies:

• Nike Air series (Air Sole/Air Max/Air Zoom)

• Adidas Springblade/4D printing

• ASICS Gel cushioning

• Li-Ning Jiang technology, Xtep Shock Absorption System

Characteristics: Resistant to compression, durable but heavier with limited cushioning potential.

(II) Foam Materials

TPE-based (Thermoplastic Elastomer) foam plastics offering lightweight properties and design flexibility. Key substrates include:

1. EVA (Ethylene-Vinyl Acetate)

• Properties: Earliest foam material, average performance, poor durability

• Positioning: Entry-level products, commonly used in insoles

• Advantages: Low cost, mature manufacturing process

%1. TPU (Thermoplastic Polyurethane)

• Representatives: Boost, Li-Ning (mid-tier), Anta Nitrogen

• Properties: High rebound, abrasion-resistant;aromatic (yellowing-prone) and aliphatic (superior performance)

• Process: Typically bead-blasted,"popcorn" appearance

3. TPEE (Thermoplastic Polyester Elastomer)

• Representative: Li-Ning (entry-tier)

• Properties: Similar rebound to TPU with 30% weight reduction

• Positioning: Cost-effective alternative to PEBA

%1. PEBA (Polyether Block Amide)

• Aliases: Nylon 12, TPA

• Representatives: Nike Zoom X, Li-Ning (premium), 361° QU!KFLAME

• Properties: Industry-leading rebound (>80%), ultra-lightweight but tear-prone

• Process: Sheet foaming offers superior performance but lower material utilization

5. Additives: STF (Shear Thickening Fluid)

• Properties: Soft under slow deformation, rigid under impact

• Applications: Peak P4U, D3O materials

• Nature: Requires blending with TPE substrates

Foaming Process Comparison

Chemical vs Physical Foaming

Process	Mechanism	Advantages	Disadvantages
Chemical	Chemical blowing agents produce gas	Low cost	Environmental concerns
Physical	Supercritical CO₂/N₂ injection	30% higher rebound	Higher production costs

Molding Technologies

Sheet Foaming

• Process: Block molding → CNC cutting

• Applications: Nike Zoom X, EVA insoles

Bead Foaming

• Process: Pre-expanded beads → steam molding

• Applications: Adidas Boost, Li-Ning

Injection Molding

• Feature: Direct molding into midsole shape

• Applications: Most EVA midsoles

Brand Technology Matrix

International Brands

• Nike: Zoom X (PEBA sheet), Air cushioning systems

• Adidas: Boost (TPU beads), Lightstrike Pro (TPEE)

• New Balance: FreshFoam (EVA blends), FuelCell (PEBA)

Domestic Brands

• Li-Ning: 䨻 (PEBA/TPU/TPEE tiered system)

• Anta: Nitrogen (EVA+PEBA/Aliphatic TPU/pure PEBA)

• Peak: Taiji (STF-blended foams)

Material Performance Comparison

Material	Rebound Rate	Weight Index	Cost	Representative
EVA	50-60%	Heavy	Low	Basic running shoes
TPU	70-80%	Medium	Medium	Adidas Boost
TPEE	75-85%	Medium-light	Medium	Li-Ning (entry)
PEBA	80-90%	Light	High	Nike Zoom X