Environmental-friendly materials：PET foam for wind turbine blades
Abstract：Against the backdrop of accelerating global wind turbine production and a worldwide shift toward low-carbon, recyclable manufacturing systems, premium blade core materials are facing increasingly tight supply conditions. Engineered to address the fast-growing demand for lightweight, sustainable core solutions, Union Composite PET foam has emerged as a versatile, high-performance alternative across wind energy, marine, transportation, and industrial composite applications. With a balanced profile of mechanical strength, thermal stability, process compatibility and circular economy benefits, PET foam is reshaping the structural core materials landscape as industries prioritize both performance and environmental responsibility.
1. Market demand
Driven by global decarbonization targets, installed wind energy capacity has expanded rapidly in recent years, driving robust demand for high-quality core materials that reinforce composite wind blades. Traditional core materials face mounting supply constraints and environmental trade-offs, leaving blade manufacturers seeking alternatives that deliver robust mechanical performance, broad process compatibility, and circular economy benefits.As low-carbon and circular economy requirements intensify across global manufacturing sectors, PET foam is emerging as a preferred alternative to non-recyclable core materials, with strong growth potential set to unlock across wind energy and adjacent industries.
2. Product features
Union Composite PET foam features an excellent balance of physical and mechanical properties that make it ideal for demanding structural sandwich structures. Its uniform closed-cell microstructure delivers consistent performance across a wide range of operating conditions.
a. Superior Mechanical Performance
With high compressive strength and modulus, the material directly enhances the load-bearing capacity and design life of wind turbine blades:
l Higher compression performance allows engineers to extend blade service lifespans and withstand harsh, cyclic operational loads over decades of use.
l At 100 kg/m³ density, PET foam delivers compressive strength exceeding 1.5 MPa and shear strength surpassing 1.2 MPa.
l PET foam demonstrates excellent fatigue resistance, with slow stiffness degradation and predictable damage evolution that benefits lifetime modeling and structural reliability.
l The homogeneous microcellular structure reduces stress concentrations, improving overall structural durability under dynamic wind loading.
b.Environmental & Circular Economy Benefits
As a thermoplastic material, PET foam stands out for its inherent recyclability, aligning with tightening environmental regulations and corporate sustainability targets:
l PET foam achieves recyclability rates above 90%, far outperforming non-recyclable alternatives such as PVC foam.
l Approximately 38% of renewable energy-grade PET cores currently contain recycled content exceeding 50%, and this share is expected to rise as recycled feedstock infrastructure expands.
l Leading industry players have already scaled recycled PET (rPET) technology, reusing over 1.7 billion PET beverage bottles in foam production and saving more than 76,800 metric tonnes of CO₂ emissions in the process.
l Over 35% of new blade designs now prefer recyclable PET cores to meet sustainability targets targeting more than 30% carbon footprint reduction.
c.Thermal & Physical Properties
l Excellent heat resistance: Long-term continuous use temperature reaches 120°C, with short-term maximum use temperature up to 200°C, accommodating most composite curing processes.
l Closed-cell structure: Closed cell rate ≥ 90%, delivering water absorption below 1% and natural anti-mildew properties for humid and outdoor environments.
l Outstanding thermal insulation: Thermal conductivity as low as 0.027 W/mK, providing effective thermal protection in addition to structural performance.
l Low thermal expansion coefficient: Matches the thermal expansion characteristics of concrete, steel, and glass fiber, minimizing internal stress during temperature cycling and improving dimensional stability.
Generally, the material exhibits low resin uptake during vacuum infusion and molding processes, reducing overall material consumption and unit production costs. Its high thermoplastic formability also enables efficient shaping and fabrication, while its inherent recyclability aligns with tightening environmental regulations and corporate sustainability targets.
3. Technical Data Sheet
PET FORM | |||||||||
Test items | Standard | Unit | Data | P80 | P100 | P120 | P80R | P100R | P120R |
Density |
ISO845 |
kg/m³ | Average value Range | 85 80-90 | 100 95-105 | 120 110-130 | 80 75-85
| 100 95-105
| 120 115-125
|
Compressive strength |
ISO844 |
MPa | Average value minimum value | 1.30 （1.10） | 1.75 （1.40） | 2.4 （2.10） | 1.15 0.90
| 1.50 1.20
| 2.10 1.80
|
Compression modulus |
ISO844 |
MPa | Average value minimum value | 75 （60） | 90 （65） | 140 (110)
| 70 60
| 85 75
| 115 105
|
Tensile strength |
ASTM C297 |
MPa | Average value minimum value | 1.9 （1.4） | 2.3 （1.5） | 2.6 (2.0)
| 1.8 1.3
| 2.2 1.6
| 2.5 2.0
|
Tensile modulus |
ASTM C297 |
MPa | Average value minimum value | 90 （80） | 110 （90） | 175 (130)
| 95 85
| 120 90
| 165 125
|
Shear strength |
ISO1922-2012 |
MPa | Average value minimum value | 0.72 （0.65） | 0.90 （0.75） | 1.30 (1.10)
| 0.68 0.60
| 0.8 0.7
| 1.25 1.10
|
Shear modulus Horizontal direction with bonding line
Perpendicular to the bonding line
Perpendicular to the bonding line
|
ISO1922-2012 |
MPa |
Average value
Average value
Minimum value |
22
19.5
16 |
26
23
19 |
34
30
25
|
19
17
|
22
18 |
28
23
|
Room temperature Thermal conductivity |
ISO8301 |
W/m.k |
Average value
|
0.034 |
0.035 |
0.036
|
0.033
|
0.034
|
0.035
|
Foam | Width | mm±5 | 1220 | 1220 | 1220 | 1220 | 1220 | 1220 | 1220 |
Length | mm±5 | 2440 | 2440 | 2440 | 2440 | 2440 | 2440 | 2440 | |
Thickness | mm±5 | 5-100 | 5-100 | 5-100 | 5-100 | 5-100 | 5-100 | 5-100 | |
