GB/T 43316.2-2023Plastics - Determination of resistance to environmental stress cracking (ESC) - Part 2: Constant tensile load method (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents" Drafting:

This document is Part 2 of GB/T 43316 "Determination of Environmental Stress Crack Resistance (ESC) of Plastics": GB/T 43316 has been released the following sections are included:

---Part 1: General principles;

---Part 2: Constant tensile load method;

---Part 3: Bending method;

---Part 4: Ball pressure or acupressure method;

---Part 5: Constant tensile deformation method;

---Part 6: Slow strain rate method:

This document is modified to adopt ISO 22088-2:2006 "Determination of environmental stress cracking (ESC) resistance of plastics - Part 2: Constant tensile load Dutch Law":

A "Terms and Definitions" chapter has been added to this document:

The technical differences between this document and ISO 22088-2:2006 and their reasons are as follows:

---Deleted the provisions on sample preparation equipment (see 4.4 of ISO 22088-2:2006), duplicating the relevant content in 8:4 of this document;

---Replaced ISO 527-2 (see 8.2) with normatively quoted GB/T 1040.2-2022 to adapt to my country's technical conditions and increase Increase operability;

---Replaced ISO 293 and GB/T 11997 with normatively quoted GB/T 9352 and replaced ISO 3167 and GB/T 17037.1 Replaced ISO 294-1 and GB/T 39812 replaced ISO 2818 (see 8.4) to adapt to my country's technical conditions and increase operability:

Doing things:

The following editorial changes have been made to this document:

---Added the content of the introduction;

---Deleted the note in Chapter 1 of ISO 22088-1:2006:

Please note that some content in this document may be subject to patents: The publisher of this document assumes no responsibility for identifying patents:

Introduction

The stress that exists externally or internally, or both, when plastics are subjected to stresses or strains below their yield point in air:

The combined action of plastics can cause cracking: This type of cracking is often accelerated by the chemical environment in which the plastic is located: This phenomenon is called environmental stress:

Cracking (ESC): ESC damage can occur in many materials, including plastics, which can significantly reduce the ability of the material to survive long-term use:

force or strain:

The ESC process is as follows:

1) After applying stress, microscopic holes are formed in the sample due to stress concentration;

2) The action of the chemical environment causes the rupture of intermolecular bonds, causing the formation and expansion of larger pores, thereby forming interconnected pores:

Silver streaks composed of holes and microfiber structures;

3) Under the combined action of stress and chemical environment, the microfiber structure breaks and silver streaks grow;

4) Cracks appear at the tip of the craze and continue to develop, eventually leading to brittle failure:

Cracks may continue to develop along the thickness of the material until the material breaks into two or more fragments; cracks may also develop when low stress is reached:

forces, different materials, and/or different morphological regions:

The ESC test is relatively complex and is affected by the following parameters:

---Sample size;

---Sample state (orientation, microstructure, internal stress);

---Sample preparation method;

---Thermal history of the specimen;

---Stress and strain;

---Test temperature;

---Test duration;

---Chemical environment;

---Methods for applying stress and strain;

---Failure criterion:

By using one parameter as a variable and keeping other parameters unchanged, the impact of variable parameters on ESC can be evaluated: The main purpose of the ESC test it is to determine the relative impact of chemical media on the plastics (specimens and products) exposed to them:

When the failure modes are consistent with those obtained in actual use, these test results can be used to evaluate molding conditions for molding:

impact on product quality:

Since the influencing factors of ESC performance of products in actual applications are more complex, it is necessary to establish the relationship between the sample ESC test results and the actual product performance:

Direct correlation is very difficult:

Environmental stress cracking testing is used as a quality control tool and in research and development to evaluate stress cracking resistance:

The test method is chosen based on the types of stresses or strains the material will be subjected to in service: When using constant strain testing methods such as the bending bar method or when using the needle intrusion method, be aware that the stress applied to the material will decay over time as the stress relaxes:

Select test conditions based on material variety and usage conditions: Compare the ESC properties of materials under the same test conditions:

GB/T 43316 "Determination of Environmental Stress Crack Resistance (ESC) of Plastics" aims to specify the environmental stress cracking resistance of thermoplastic plastics:

The general principles and description of its determination methods are intended to be composed of six parts:

---Part 1: General principles: The purpose is to establish general principles for determining the resistance of plastics to environmental stress cracking:

---Part 2: Constant tensile load method: The purpose is to establish the resistance of thermoplastics to a constant tensile load in a test medium:

An operational, traceable, and verifiable determination procedure for environmental stress cracking:

---Part 3: Bending method: The purpose is to establish thermoplastics capable of withstanding fixed bending strains in the presence of test agents:

An operational, traceable, and verifiable determination procedure for environmental stress cracking resistance:

---Part 4: Ball pressure or acupressure: The purpose is to establish a thermoplastic ring that can withstand constant strain when a ball or needle is pressed into it:

Operable, traceable, and verifiable measurement procedures for environmental stress cracking:

---Part 5: Constant tensile deformation method: The purpose is to establish a test medium for thermoplastics when subjected to constant tensile deformation:

Operable, traceable, and verifiable testing procedures for environmental stress cracking resistance:

---Part 6: Slow strain rate method: The purpose is to establish for thermoplastics slowly increasing tension at a constant rate in the test medium:

An operable, traceable and verifiable determination procedure for environmental stress cracking resistance under tensile specimen strain conditions:

Part 2 and other parts support each other and together form a standard system for determining the environmental stress cracking resistance of plastics:

The above tests for environmental stress cracking (ESC) resistance are essentially rating tests and are not intended to provide information for design or performance prediction:

data:

Determination of environmental stress cracking (ESC) resistance of plastics Part 2: Constant Tensile Load Method

1 Scope

This document describes a test method for the resistance of thermoplastics to environmental stress cracking (ESC) when subjected to a constant tensile load in a chemical medium:

This document applies to specimens prepared by molding and/or machining for the determination of environmental stress cracking resistance of plastics exposed to different environments:

Environmental stress cracking resistance of different plastics when exposed to specific environmental conditions:

2 Normative reference documents

The contents of the following documents constitute essential provisions of this document through normative references in the text: Among them, the dated quotations for undated referenced documents, only the version corresponding to that date applies to this document; for undated referenced documents, the latest version (including all amendments) applies to this document:

GB/T 1040.2-2022 Determination of tensile properties of plastics Part 2: Test conditions for molded and extruded plastics (ISO 527-2:

2012,MOD)

GB/T 9352 Compression molding of plastic thermoplastic material samples (GB/T 9352-2008, ISO 293:2004, IDT) GB/T 11997 Plastic multi-purpose specimens (GB/T 11997-2008, ISO 3167:2002, IDT) GB/T 17037.1 Preparation of injection molded specimens of plastic thermoplastic materials - Part 1: General principles and multi-purpose specimens and lengths Preparation of strip specimens (GB/T 17037.1-2019, ISO 294-1:2017, MOD) GB/T 39812 Machining preparation of plastic specimens (GB/T 39812-2021, ISO 2818:2018, IDT) GB/T 43316.1-2023 Determination of environmental stress cracking (ESC) resistance of plastics Part 1: General principles (ISO 22088-1:2006, MOD) Note: There is no technical difference between the quoted content of GB/T 43316.1-2023 and the quoted content of ISO 22088-1:2006:

3 Terms and definitions

There are no terms or definitions to be defined in this document:

4 Principles

Apply a constant tensile load below the yield stress to the specimen while immersing it in the test medium at the selected temperature, and record the damage of the specimen:

time and/or stress:

According to the failure time, choose the following method to measure the environmental stress cracking resistance of the sample:

---Method A: Determine the tensile stress when the failure time is equal to 100h, that is, the interpolated value on the tensile stress-failure time curve is accurate Determine the tensile stress corresponding to the failure time of 100h;

---Method B: Determine the failure time under specified tensile stress: Use this method when the failure time exceeds 100h;

---Method C: Determine the failure time corresponding to a series of applied stresses, and determine the specific application through the tensile stress-failure time curve the failure time corresponding to the stress: