GB/T 43316.3-2023Plastics - Determination of resistance to environmental stress cracking (ESC) - Part 3: Bent strip 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 3 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 has been modified to adopt ISO 22088-3:2006 "Determination of environmental stress cracking (ESC) resistance of plastics - Part 3: Bending method":

The technical differences between this document and ISO 22088-3:2006 and their reasons are as follows:

---Replaced ISO 527-2 (see 3.5, 8:5) with normatively cited GB/T 1040.2, and GB/T 9341 replaced ISO 178 (see 3.5, 8:5) to adapt to my country's technical conditions and increase operability;

---The test method for tensile impact strength has been changed to increase operability;

---Replaced ISO 22088-1:2006 (see 7.3) with normatively cited GB/T 43316.1-2023 to adapt to my country's technology conditions, increase operability;

---Added a method of using graphs to determine failure strain (see 9.2) to improve test operability;

---Deleted the requirement for measuring the thickness of the specimen (see 5.4 of ISO 22088-3:2006) to adapt to my country's technical conditions and increase operability:

Doing things:

The following editorial changes have been made to this document:

---Deleted ISO 2818 that was not cited in ISO 22088-3:2006;

---Deleted the note in Chapter 1;

---Deleted Note 1 and Note 4 in Table 1;

---The note in 5:1 is changed to the text content:

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

When a plastic is subjected to an action below its yield stress in the air, the stress existing in the outside or inside, or the combination of both stresses can Causes cracking, which is often accelerated by the chemical environment in which the plastic is located: This phenomenon is called environmental stress cracking (ESC):

ESC failure can occur in many materials, including plastics, which can significantly reduce the stress or strain that allows the material to be used for long periods of time:

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 the purpose is to determine the relative effects of chemical media on the plastics (specimens and articles) to which they are exposed:

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 product ESC performance in actual applications are more complex, the sample ESC test results and actual product performance are established:

Direct correlation is very difficult:

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 environmental stress cracking resistance of plastics:

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

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

---Part 3: Bending method; the purpose is to establish when thermoplastics are subjected to a fixed bending strain in the presence of test reagents Operable, traceable, and verifiable testing procedures for environmental stress cracking resistance:

---Part 4: Ball pressure or needle pressure method; the purpose is to establish the environmental resistance of thermoplastics when ball or needle pressure creates constant strain:

Actionable, traceable, and verifiable determination procedures for stress cracking:

---Part 5: Constant tensile deformation method; the purpose is to establish the properties of thermoplastics when subjected to constant tensile deformation in the test medium:

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

---Part 6: Slow strain rate method; the purpose is to establish a method for thermoplastics to slowly increase the sample stress at a constant rate in the test medium:

Operable, traceable, and verifiable measurement procedures for environmental stress cracking resistance under varying conditions:

Part 3 and other parts of this series of standards support each other and together constitute the standard for determining the environmental stress cracking resistance of plastics system:

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 3: Bending method

1 Scope

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

This document is suitable for determining the environmental stress cracking resistance of plates and flat specimens, especially the environmental stress cracking resistance of local surface areas:

crack-sensitive specimens, determination of gases and liquids as well as solids containing migrating substances (such as polymer adhesives and materials containing plasticizers) and Resistance to environmental stress cracking caused by contact with specific polymers, as well as determination of the resistance of rigid plastics that exhibit only moderate stress relaxation during testing Environmental stress cracking properties:

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 Determination of tensile properties of plastics Part 2: Test conditions for molded and extruded plastics (GB/T 1040.2-2022,ISO 527-2:2012,MOD) GB/T 9341 Determination of bending properties of plastics (GB/T 9341-2008, ISO 178:2001, IDT) GB/T 43316.1-2023 Determination of environmental stress cracking (ESC) resistance of plastics Part 1: General principles (ISO 22088-1:

2006,MOD)

3 Terms and definitions

The following terms and definitions apply to this document:

bending strainflexuralstrain epsilonx when the tensile surface of the specimen is bent into an arc (see Figure 1 for a schematic diagram), the nominal value of the tensile surface strain is calculated by formula (1):

epsilonx=

In the formula:

epsilonx---nominal value of tensile surface strain;

h ---Sample thickness, in millimeters (mm);

r ---Bending radius of the specimen, in millimeters (mm):