Overview
ISO 899-2:2003/Amd 1:2015 is an amendment to the international standard for determining the creep behaviour of plastics, specifically focusing on flexural creep by three-point loading. Published by the International Organization for Standardization (ISO), this document updates the original ISO 899-2:2003 standard by enhancing guidance on evaluating the time-dependent deformation of plastic materials under flexural stress.
The standard is essential for manufacturers, engineers, and researchers seeking reliable methods to assess the long-term mechanical performance of plastic components subjected to bending forces. It emphasizes the influence of temperature and physical ageing on creep, providing detailed insights into how plastics behave under sustained mechanical loads and temperature variations.
Key Topics
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Flexural creep testing by three-point loading:
The standard defines a test method using three-point bending to evaluate creep deformation of plastic specimens, enabling accurate measurement of flexural creep over time.
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Physical ageing effects:
Amendment 1 elaborates on the complex impact of physical ageing on creep behaviour, especially when plastic specimens undergo temperature changes before or during testing. It explains how molecular mobility and structural changes influence deformation rates.
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Elevated temperature testing:
The document discusses how increased temperatures accelerate creep deformation due to enhanced molecular mobility and reduced physical age of polymers. Tests performed after thermal storage periods reveal time-dependent changes in creep characteristics.
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Transient creep behaviour:
The standard highlights that creep curves may shift with dwell time at elevated temperatures, requiring adjustments in analyzing data for accurate long-term predictions. It warns against oversimplified time-temperature superposition approaches without accounting for physical ageing effects.
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Influence of polymer structure:
The amendment covers how the amorphous and semi-crystalline phases of plastics contribute to creep behaviour, noting that relaxation processes at the molecular level affect deformation during long-term loading.
Applications
This standard is highly valuable across industries where plastics are used in load-bearing and structural applications, including but not limited to:
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Automotive parts:
Predicting long-term deformation under mechanical loads and temperatures typical in vehicle components.
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Electrical and electronic housings:
Ensuring dimensional stability and integrity when plastics are subjected to flexural stresses over time.
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Construction materials:
Assessing durability of polymer-based panels, pipes, and fittings under sustained bending forces.
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Consumer goods:
Improving reliability of plastic products expected to undergo prolonged mechanical stress.
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Research and development:
Guiding material formulation and performance optimization by understanding creep mechanisms influenced by temperature and physical ageing.
Related Standards
Professionals implementing ISO 899-2:2003/Amd 1:2015 often also consider related standards that address plastics testing and mechanical performance, such as:
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ISO 899-1: Determination of creep behaviour - Part 1: Tensile creep methods.
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ISO 527: Plastics - Determination of tensile properties.
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ISO 75: Plastics - Determination of temperature of deflection under load.
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ISO/IEC Directives Part 1 & 2: Procedures and editorial guidelines for developing ISO standards.
Integrating ISO 899-2 with these complementary standards facilitates a comprehensive evaluation of plastics’ mechanical properties over varied loading conditions and environmental factors.
Keywords: ISO 899-2 amendment, plastics creep behaviour, flexural creep testing, three-point loading, physical ageing in plastics, elevated temperature creep, polymer mechanical properties, plastic deformation, long-term plastic testing, creep master curves.
Open preview (PDF)Plastics — Determination of creep behaviour — Part 2: Flexural creep by three-point loading — Amendment 1