ASTM D2734 Void Content Testing for Fiber Reinforced Plastics

The ASTM D 2734 Standard Test Methods addresses the void content of reinforced polymers or "composites." The test procedures can be used with composites whose materials' reactions to ignition are known. This category includes most plastics, glass, and reinforcements. The effects of ignition on the plastics do not apply to these test techniques for composite materials.

Talk to an Expert

ASTM D2734 Void Content Testing for Fiber Reinforced Plastics

TRUSTED BY

Precision-driven testing for dimensional accuracy and compliance

Overview
Scope, Applications, and Benefits
Test Process
Specifications
Instrumentation
Results and Deliverables

Overview

ASTM D2734 establishes a method for determining the void content in reinforced plastic composites by comparing measured density with theoretical density. Voids are trapped air or gas pockets formed during manufacturing, which can significantly reduce mechanical strength, stiffness, and long-term durability of composite materials. Accurate quantification of void content is critical for ensuring structural integrity and performance.

This test is widely used in composite manufacturing processes such as molding, filament winding, and lamination. By identifying void levels, manufacturers can optimize processing parameters, improve consolidation, and ensure high-quality composite structures for demanding applications requiring strength, reliability, and consistency.

Scope, Applications, and Benefits

Scope

ASTM D2734 defines procedures for calculating void content in reinforced plastics using density measurements and theoretical composition data.

Applicable to fiber-reinforced plastic composites
Determines void content based on density comparison
Requires knowledge of resin and reinforcement proportions
Supports evaluation of manufacturing quality and consolidation
Suitable for laboratory testing and quality assurance processes

Applications

Aerospace composite component evaluation
Automotive structural composite testing
Marine and wind energy composite structures
Quality control in composite manufacturing
Research and development of reinforced plastics

Benefits

Identifies internal defects affecting performance
Improves mechanical strength and durability of composites
Supports optimization of manufacturing processes
Enhances product reliability and consistency
Enables comparison of composite quality

Test Process

Specimen Preparation

Composite sample is cut and conditioned to obtain representative material for density measurement.

Density Measurement

Actual density is determined using appropriate methods such as displacement or mass-volume calculation.

Theoretical Density Calculation

Density is calculated based on known proportions of resin and reinforcement materials.

Void Content Determination

Void percentage is calculated by comparing measured density with theoretical density values.

Technical Specifications

Parameter	Details
Material Type	Fiber-reinforced polymer composites
Test Principle	Density comparison between actual and theoretical values
Measurement Output	Void content expressed as percentage (%)
Density Method	Displacement or mass-volume calculation
Input Requirement	Resin and fiber weight fractions
Environment	Controlled laboratory conditions

Instrumentation Used for Testing

Analytical balance
Density measurement setup (displacement apparatus)
Calipers or micrometer
Sample cutting tools
Conditioning chamber
Data calculation tools
Calibration standards

Results and Deliverables

Actual and theoretical density values
Calculated void content (%)
Assessment of composite quality
ASTM D2734 compliant test report
Recommendations for process improvement

Frequently Asked Questions

ASTM D2734 is a standard test method used to determine void content in reinforced plastic composites by comparing actual and theoretical density. It is important because voids can significantly reduce strength, durability, and overall structural performance of composite materials.

Void content directly affects strength, stiffness, and fatigue resistance. High void levels can lead to premature failure, making it essential to control and measure voids for high-performance applications.

The test relies on accurate composition data and density measurements. It does not provide detailed information about void distribution, requiring additional methods for comprehensive analysis.

It significantly contributes by identifying void-related defects, but overall reliability also depends on material selection, processing conditions, and additional performance testing.

Factors include improper curing, inadequate pressure, resin viscosity, air entrapment, and processing conditions, all of which can affect the formation of voids during manufacturing.

Why Choose Infinita Lab
for Electron Energy Loss
Spectroscopy (EELS)?

At the core of this breadth is our network of 2,000+ accredited labs in the USA, offering access to over 10,000 test types. From advanced metrology (SEM, TEM, RBS, XPS) to mechanical, dielectric, environmental, and standardized ASTM/ISO testing, we give clients unmatched flexibility, specialization, and scale. You are not limited by geography, facility, or methodology – Infinita connects you to the right testing, every time.