ASTM D1929 Test Lab

ASTM D1929 is a standard test method for determining the ignition temperature of plastics. This test method is used to evaluate the fire hazard of plastics by measuring the temperature at which they ignite when exposed to a heat source under controlled laboratory conditions.

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

Overview

ASTM D1921 establishes a standardised method for determining the particle size distribution of plastic materials in granular or powdered form using sieve analysis. Understanding particle size is fundamental to predicting how a plastic material will process, flow, and perform in end-use applications.

The test involves passing a sample of plastic material through a series of calibrated sieves with progressively smaller openings. The weight retained on each sieve is measured and expressed as a percentage of the total sample weight. This data is used to generate a particle size distribution profile, which helps manufacturers maintain consistency in raw materials and finished products. ASTM D1921 provides two procedures: Procedure A for coarse particles and Procedure B for fine particles, making it applicable across a wide range of granule sizes used in plastic processing.

Scope, Applications, and Benefits

Scope

ASTM D1921 evaluates the particle-size distribution of plastic granules and powders to assess the uniformity, consistency, and quality of raw materials. The test uses a standardised sieve analysis method to measure how the material is distributed across different particle size intervals. It helps quantify the percentage of material retained on each sieve, enabling manufacturers and quality control teams to verify whether the supplied material conforms to purchase specifications and processing requirements.

ASTM D1921 evaluates:

Particle size distribution of plastic granules and powders
Percentage of material retained at each sieve interval
Uniformity and consistency of plastic raw materials
Conformance of received materials to purchase specifications
Fine particle content (dust) in granular materials
Oversized particle content in powdered materials

Applications

Plastic resin quality control
Raw material incoming inspection
Powder coating materials
Rotational molding feedstocks
Compounding and blending operations
Recycled plastic material characterization
Research and development

Benefits

Ensures raw material consistency
Supports process optimisation
Reduces molding defects caused by non-uniform particle size
Enables supplier qualification
Provides compliance documentation
Improves flow and packing characteristics in processing

Test Process

Sample Preparation

A representative sample is dried and weighed to the specified mass.

Sieve Stack Assembly

Sieves are arranged from largest to smallest opening and placed on a mechanical shaker.

Sieving

The sample is placed on the top sieve and shaken for the prescribed duration.

Weighing & Calculation

Material retained on each sieve is weighed, and percent retained/passing is calculated.

Technical Specifications

Parameter	Details
Test Principle	Mechanical sieve separation
Procedures	Procedure A (coarse), Procedure B (fine)
Applicable Materials	Plastic granules and powders
Output Units	% retained by weight per sieve fraction
Measured Outputs	Particle size distribution, percent fines, percent oversize

Instrumentation Used for Testing

Calibrated wire-cloth test sieves
Mechanical sieve shaker
Analytical balance
Drying oven
Sample splitter/divider
Data recording software

Results and Deliverables

Particle size distribution table and curve
Percent retained and percent passing values
Oversized and fine content data
Compliance documentation
Quality assurance reports
Comparative analysis against specification limits

Why Choose Infinita Lab for ASTM D1929?

Infinita Lab is a leading provider of ASTM D1929 and streamlined material testing services, addressing the critical challenges faced by emerging businesses and established enterprises. With access to a vast network of over 2,000+ accredited partner labs across the United States, Infinita Lab ensures rapid, accurate, and cost-effective testing solutions. The company’s unique value proposition includes comprehensive project management, confidentiality assurance, and seamless communication through a Single Point of Contact (SPOC) model. By eliminating inefficiencies in traditional material testing workflows, Infinita Lab accelerates research and development (R&D) processes.

Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote

Frequently Asked Questions

ASTM D1921 is a standard test method used to determine the particle size distribution of plastic materials in powdered, granular, or pelleted form using dry sieve analysis. It helps assess raw material uniformity and consistency.

This test is suitable for plastic powders, granules, pellets, and similar particulate polymer materials commonly supplied as raw materials for manufacturing and compounding processes.

Particle size directly affects flowability, feeding behaviour, blending efficiency, melting consistency, and processing performance during molding, extrusion, and compounding operations.

Since the method uses dry sieving, the lower limit is approximately 38 µm (No. 400 sieve). For particles smaller than this, sedimentation-based methods are generally recommended.

A known dry mass of material is placed on a stack of standard sieves arranged from coarse to fine. The stack is mechanically shaken, and the mass retained on each sieve is measured and reported as a percentage.