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3240 epoxy glass cloth laminated sheets are high-performance composite materials made by impregnating woven fiberglass cloth with epoxy resin and curing it under high pressure and temperature. Widely used in electrical, electronic, and mechanical industries, these laminates exhibit an excellent combination of electrical insulation, mechanical strength, thermal stability, and dimensional accuracy. In this blog post, as a high performance epoxy resin laminate manufacturing factory, Blue Sun will share the mechanical properties of 3240 epoxy glass cloth laminated sheet for sale.

Composition and Structural Features

The 3240 laminated sheet is manufactured from an alkali-free woven fiberglass fabric, thoroughly impregnated with thermosetting epoxy resin and laminated under heat and pressure. The result is a dense, void-free material with a uniform matrix and reinforcement distribution. The woven fiberglass cloth provides directional strength and toughness, while the epoxy resin imparts chemical resistance, dimensional stability, and dielectric properties.

Key characteristics of the structural design:

* Reinforcement Material: Woven E-glass cloth

* Resin Matrix: Modified epoxy resin (thermoset)

* Density: Typically ranges between 1.8 – 2.0 g/cm³

* Thickness Range: Available in various thicknesses from 0.5 mm up to 50 mm

Tensile Strength

Tensile strength refers to the maximum stress a material can withstand while being stretched or pulled before failing. The tensile strength of 3240 epoxy glass cloth laminated sheets is significantly influenced by the alignment and bonding of fiberglass yarns and the integrity of the resin system.

* Typical Tensile Strength (Lengthwise): ≥ 340 MPa

* Typical Tensile Strength (Crosswise): ≥ 270 MPa

This anisotropic behavior arises because the woven fabric has more fiber density and alignment in the warp direction. The high tensile strength ensures that the sheet can endure structural loads without fracture, making it suitable for structural components and enclosures in heavy-duty environments.

Flexural Strength

Flexural or bending strength is a measure of a material’s resistance to deformation under load. For laminated composites, this parameter is critical in applications where bending stresses are common, such as in support brackets, insulation boards, and mechanical covers.

* Typical Flexural Strength (Lengthwise): ≥ 350 MPa

* Typical Flexural Strength (Crosswise): ≥ 290 MPa

The excellent flexural performance is attributed to the synergy between the rigid epoxy resin and the tensile-tough fiberglass. This property ensures the material does not crack or delaminate easily during service.

Compressive Strength

Compressive strength reflects the material's ability to resist deformation or failure under a crushing load. Due to the cross-linked epoxy matrix and tightly packed fabric layers, 3240 laminates perform exceptionally well under compressive forces.

* Compressive Strength (Parallel to Lamination): ≥ 300 MPa

* Compressive Strength (Perpendicular to Lamination): ≥ 260 MPa

This high compressive strength makes the material suitable for use in structural and insulating supports that bear substantial static or dynamic loads.

Shear Strength

Shear strength is crucial in evaluating the material's resistance to sliding failure along the lamination plane. Laminated composites often exhibit lower shear strength compared to tensile or compressive strengths due to the weaker interlaminar bonding.

* Interlaminar Shear Strength: ~25–35 MPa

To improve shear performance, careful resin impregnation and curing cycles are critical. Applications requiring high shear stress handling, such as mechanically fixed panels or bolted assemblies, must be designed to accommodate this property.

Impact Strength

Impact resistance denotes the ability of a material to absorb energy during sudden loading or shock without fracturing. This parameter is critical for determining the material’s behavior under dynamic or accidental loading.

* Charpy Impact Strength (Unnotched): ≥ 33 kJ/m²

* Charpy Impact Strength (Notched): ≥ 20 kJ/m²

The woven glass fibers act as crack stoppers, while the epoxy resin provides toughness and adhesion, allowing the laminate to absorb impact energy and minimize damage.

Hardness

The hardness of 3240 epoxy glass laminated sheets is typically measured using the Rockwell or Barcol scale. High surface hardness implies better scratch resistance and dimensional durability during prolonged service.

* Rockwell Hardness (M-scale): ≥ 100

* Barcol Hardness: 40–50

This hardness range ensures the material maintains dimensional stability under mechanical wear and resists gouging or surface indentation.

Modulus of Elasticity

The modulus of elasticity (Young’s Modulus) quantifies the stiffness of the material. In composite laminates, it varies directionally based on fiber orientation and resin-to-fiber ratio.

* Modulus of Elasticity (Lengthwise): ~20–25 GPa

* Modulus of Elasticity (Crosswise): ~15–18 GPa

A high modulus in the longitudinal direction supports the use of 3240 laminates in precision instruments and components where dimensional control and rigidity are paramount.

Dimensional Stability and Creep Resistance

Due to the thermoset nature of the epoxy and the woven glass structure, 3240 laminated sheets demonstrate exceptional resistance to dimensional change under load or temperature variations.

* Water Absorption: < 0.5%

* Thermal Expansion Coefficient: ~1.8–2.2 × 10⁻⁵ /°C

* Creep Resistance: Excellent under standard load/temperature ranges

These properties are essential in environments demanding long-term geometric precision, such as electronic insulators and mechanical jigs.

Flammability and Thermal Performance

Though the focus here is on mechanical characteristics, it’s worth noting that 3240 epoxy glass laminates also offer good thermal stability:

* Continuous Operating Temperature: ~130°C

* Short-term Thermal Endurance: ~155°C

* Flammability Rating: UL 94 HB (Self-extinguishing)

This allows their use in mechanically loaded, thermally stressed applications such as switchgear panels and motor insulation structures.

Comparative Advantage Over Other Laminates

Compared to paper-based laminates (e.g., phenolic-paper Bakelite), 3240 epoxy glass cloth sheets provide:

* Greater mechanical strength and rigidity

* Superior impact and wear resistance

* Enhanced thermal endurance

* Longer service life under dynamic loads

While more expensive, 3240 laminates justify their cost in critical applications requiring reliability, load-bearing capacity, and minimal failure risk.

Common Applications Requiring Superior Mechanical Properties

Owing to their excellent mechanical behavior, 3240 epoxy glass cloth laminated sheets are used in:

* Electrical panel boards and structural insulators

* Busbar support brackets

* Transformer and motor slot wedges

* Tooling fixtures and jigs in precision engineering

* Rotor blade end plates and armature insulation

* PCB support plates and semiconductor module carriers

In each case, the material's mechanical integrity, along with its insulation and thermal resistance, ensures optimal performance.

Conclusion

The mechanical properties of 3240 epoxy glass cloth laminated sheets make them a premier choice for high-performance applications in electrical, mechanical, and structural engineering fields. With exceptional tensile, compressive, flexural, and impact strength, alongside excellent dimensional stability and thermal resistance, these sheets are indispensable in environments where material failure is not an option. As the demand for robust and reliable insulation and structural materials continues to grow, 3240 laminates will remain a cornerstone in composite engineering solutions.

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