A Must-Read For Wind Turbine Blades: Fiberglass Chopped Strand Mat Models And Selection Guide

I. Chopped Strand Mat for Wind Turbine Blades: Basic Positioning and Core Requirements

Choped strand mat for wind turbine blades uniformly uses alkali-free E-glass fiber with a fiber diameter of 9–13 μm and a chopped length of 12–25 mm, meeting GB/T 17470 standard and compatible with epoxy resin/vinyl ester resin systems.

 

Key Performance Thresholds

- Unit area mass deviation: ±5%

- Moisture content: ≤0.2%

- Tensile strength: ≥30–180 N/5cm (increasing with basis weight)

- Impregnation: Fast impregnation, low bubble formation, suitable for vacuum infusion

- Weather resistance/salt spray resistance: Requires enhanced corrosion resistance for offshore models

- Stability: No powdering, no delamination, no fuzz, suitable for automated layup

Choped strand mat in blades primarily serves to reinforce non-load-bearing components, homogenize the surface, facilitate interlayer transition, and resist deformation. It is used in conjunction with unidirectional fabrics, multiaxial fabrics, continuous mats, and surface mats to form a complete structural layer.

 

II. List of Wind Turbine Blade Chopped Strand Felt Models and Specifications

The mainstream models in the industry are EMC (emulsion)/CMC (powder), with common widths of 1250/1040/2500mm. The following are the most commonly used models in mass production of blades:

 

1) Standard Models and Weight Correspondence

- EMC225/CMC225: 225g/㎡, thin transition layer, smooth surface

- EMC300/CMC300: 300g/㎡, general-purpose mainstay, suitable for both shell and web

- EMC450/CMC450: 450g/㎡, medium-thickness reinforcement, strengthening of stress areas

- EMC600/CMC600: 600g/㎡, thick reinforcement, thickening at the root/leading edge

- EMC900: 900g/㎡, heavy-duty reinforcement, localized reinforcement for large blades

2) Adhesive Type Selection

- Emulsion-type EMC: High strength, good uniformity, excellent resin compatibility, preferred for vacuum infusion.

- Powder-type CMC: Faster impregnation, lower cost, suitable for hand lay-up/auxiliary processes.

- Offshore wind power, high-strength blades: EMC emulsion series preferred.

3) Width and process matching

- 1250mm/1040mm: Small and medium blades, manual lay-up.

- 2500mm and above: Large blades, automated lay-up, reduced overlap.

 

III. Selection by location: How to match different areas of the blade?

1) Shell Outer Surface/Gelcoat Underlayer

- Recommended: EMC225 / EMC300

Key Points: Smooth surface, reduced pinholes, improved appearance and weather resistance

2) Shell Main Body Layer (Transition/Balancing Layer)

- Recommended: EMC300

Key Points: Balanced strength and impregnation, optimal for use with multi-axial fabrics

3) Web, Beam Cap Side Reinforcement

- Recommended: EMC450

Key Points: Higher stiffness, shear resistance, improved structural stability

4) Leading Edge, Trailing Edge, Root Thickened Area

- Recommended: EMC600 / EMC900

Key Points: Thick layer rapid forming, reduced layup count, improved impact resistance

5) Offshore Wind Turbine Blades (Salt Spray/High Humidity)

- Recommended: Low-feather EMC300/450 + Hydrolysis-resistant wetting agent

Key Points: Improved aging resistance, reduced delamination risk

 

IV. Chopped Straight Strand Mat vs. Other Fiberglass Mats: Why are they preferred for blades?

1) Chopped Straight Strand Mat vs. Continuous Fabric Mat

- Chopped Strand Mat: Isotropic, good molding, suitable for curved surfaces and infusion

- Continuous Fabric Mat: Higher longitudinal strength, slightly weaker uniformity

- Blade Assembly: Chopped strand mat for the main body, continuous/unidirectional fabric for the main load-bearing areas

2) Chopped Strand Mat vs. Stitched Fabric Mat

- Stitched Fabric Mat: Higher strength, higher price

- Chopped Strand Mat: Process-friendly, cost-effective, fewer defects

- Selection: Chopped strand mat is more stable and economical in non-main load-bearing areas

3) Chopped Strand Mat vs. Surface Mat

- Surface Mat: 30–120g/㎡, only for surface sealing

- Chopped Strand Mat: Dual function of structural reinforcement + surface uniformity

- Combination: Surface Mat + Chopped Strand Mat + Multiaxial Fabric This is a standard blade layup.

 

V. Five-Step Selection Method

1. Check the process: Vacuum infusion → Choose EMC emulsion; Hand layup → CMC powder can be used.

2. Check the location: Curved surface/appearance → 225/300g; Reinforcement → 450/600g; Heavy load → 900g

3. Check the resin: Epoxy system → Confirm wetting agent compatibility; Marine → Hydrolysis resistant type

4. Check the width: Use wide width for large blades to reduce overlap and defects.

5. Check the quality: Basis weight deviation ≤ ±5%, moisture content ≤ 0.2%, no powder shedding and no fuzz.

 

VI. Common Misconceptions and Avoidances

- Focusing only on price and ignoring the binder: Powder felt is prone to uneven impregnation when used in infusion.

- Increasing basis weight arbitrarily: Excessive thickness can easily lead to insufficient infusion and interlayer defects.

- Ignoring width and overlap: Excessive overlap increases the risk of air bubbles and dry spots. Suitable for both offshore and onshore applications: For offshore applications, a hydrolysis-resistant/low-feather-specific model is required.

 

VII. Summary: Wind Turbine Blade Fiberglass Chopped Strand Mat Selection in One Sentence

Use 225/300g for appearance and transition, and 450/600g for structural reinforcement; prioritize EMC emulsions for vacuum infusion, and choose hydrolysis-resistant, low-feather-resistant mats for offshore wind power; match weight according to location and select adhesive according to process, ensuring stability, strength, and process are all addressed in one go.

 

Blade materials are of paramount importance. Correct selection can improve yield, reduce costs, and guarantee a fatigue life of over 20 years. We recommend customers establish a list of corresponding models, locations, processes, and resins for standardized procurement and layup, making the composite material system more reliable.