1 Scope
This document describes the test method for the tensile and compression cyclic durability of sealants under artificial weathering, including an overview, equipment and materials, general test rules, test piece preparation, test procedure, results and evaluation, and test report.
This document is applicable to the evaluation of the ageing resistance of sealants.
2 Normative references
The contents of the following documents constitute the essential provisions of this document through the normative references in the text. Among them, note the date of the reference document, only the date of the corresponding version applies to this document; not note the date of the reference document, its latest version (including all the revision of the list) applies to this document.
GB/T 2943 Terminology of Adhesives
GB/T 13477.1 Test Methods for Building Sealing Materials Part 1: Provisions for Test Substrates (GB/T 13477.1-2002, ISO 13640:1999, MOD)
GB/T 16422.1-2019 Plastics - Laboratory light source sensitivity test method - Part 1: General (ISO 4892-1: 2016, IDT)
GB/T 16422.2-2014 Plastics Experiments - Exposure Test Method of Empty Light Sources - Part 2: Arc Lamp (ISO 4892-2:2006, IDT)
GB/T 16422.3-2014 Plastics - Methods of exposure to laboratory light sources - Part 3: Fluorescent ultraviolet lamps (ISO 4892-3:2006, IDT)
GB/T 16422.4-2014 Plastics - Methods of exposure to laboratory light sources - Part 4; Open carbon arc lamp (ISO4892-4:2004, IDT)
GB/T 21526-2008 Structural Adhesives, Guidelines for Surface Treatment of Metals and Plastics before Bonding (ISO 17212:2004, 1DT)
GB/T 41745 Photographic Method for Evaluating Aging Cracks of Sealants (GB/T 41745-2022,1SO 115281:2016, MOD)
3 Terms and definitions
The terms and definitions defined in GB/T2943 apply to this document.
4 Overview
The test piece is made by bonding the sealant between two parallel substrate surfaces. After curing, the test piece is subjected to artificial ageing conditions for a specified period of time and after a specified range of tensile and compressive cycles, and the durability class of the sealant is determined on the basis of the damage and surface condition of the test piece.
5 Equipment and materials
5.1 Substrate
The substrate material may be concrete, glass, anodised aluminium, in accordance with GB/T 13477.1, or as mutually agreed.
Note that the two pieces of substrate for each test piece should be of the same material, the size of the substrate is variable, but the size of the bonding area should be 12 mm x 12 mm x 50 mm, see Figure 1 or Figure 2.
5.2 Retainers
Anti-adhesive surface material with a cross-sectional dimension of 12 mm x 12 mm,
5.3 Backing material
The material can be polyethylene, PTFE anti-adhesive film or anti-adhesive paper, etc. for the preparation of the test piece.
5.4 Tensile testing machine
Equipped with recording device, adjustable stretching rate of 5.5±0.5mm/min.
5.5 Limit blocks and clamps
Used to control the width of the specimen being stretched or compressed, so that the specimen remains stretched or compressed at a width equivalent to 12.5%, 20%, 25% of the original width, or any other width agreed between the parties.
5.6 Gauges
To an accuracy of 0.05 mm.
5.7 Illuminator
For illuminating the back of the test piece.
5.8 Artificial accelerated weathering chamber
The artificial accelerated weathering test chamber shall conform to the requirements of GB/T 16422.1-2019,GB/T 16422.2-2014,GB/T 16422.3-2014,GB/T 16422.4-2014 and can expose the specimen to the specified temperature, relative humidity, wetting and light conditions.
5.9 Laboratory light source
5.9.1 Argon arc light source
5.9.2 Fluorescent ultraviolet light source using UVA-340 fluorescent lamps, whose optical harmonic energy distribution shall comply with the requirements of GB/T 16422.3-2014, Table 1,A.1. 5.9.3 Open carbon arc light source using open carbon arc lamps with daylight filters 5.9.3 open carbon arc lamps with daylight filters, the spectral energy distribution should be consistent with the requirements of GB/T 16422.4-2014 in Table 1.
5.10 Thermometers
The black standard thermometer and black plate thermometer should comply with the requirements of 5.2 in GB/T 16422.1-2019.
The thermometer should be fixed to the specimen holder so that it is torched away from the lamp at the same distance as the specimen from the lamp and is subjected to the same effects as the specimen.
Note: Under the given conditions, the black plate temperature is 3℃~12℃ lower than the black standard temperature, and the difference between the two is smaller when the irradiance is low.
6 General rules for testing
6.1 Standard test conditions
Temperature (23±2)℃ , relative humidity (50±10)%.
6.2 Artificial climate ageing test conditions
6.2.1 Argon arc lamp (default)
Use the argon arc lamp equipment with daylight type filter, dense arc lamp equipment test conditions are shown in Table 1.
6.2.2 Fluorescent UV lamp (optional)
Use a UVA-340 (Type 1A) fluorescent UV lamp. The test conditions for the fluorescent UV lamp are shown in Table 2.
6.2.3 Open type carbon arc lamp (optional)
An open carbon arc lamp apparatus with a daylight type (Type 1) filter is used. The test conditions for the open carbon arc lamp apparatus are shown in Table 3.
6.3 Tensile-compression cyclic conditions of specified amplitude
The sealant displacement classes and the corresponding test specimens are shown in Table 4 for the tensile-compression amplitudes and corresponding widths.
7 Specimen preparation
7.1 Conditioning of the specimen
The sealant sample and the test substrate shall be left at (23°C) for at least 16 h.
7.2 Surface treatment of the substrate
According to GB/T 21526-2008 method, or according to the method provided by the sealant product supplier
7.3 Specimens
Single-component products are sampled directly from the original packaging.
Multi-component samples are mixed according to the ratios and procedures provided by the sealant supplier and then formed into specimens.
7.4 Construction of the specimen model
Two pieces of substrate and two blocks are assembled on the backing material to form a cavity model as shown in Figure 1 or Figure 2.
7.5 Filling with sealant
Squeeze the specimen into the cavity, taking care to avoid the formation of air bubbles during the filling process.
7.6 Specimen handling
7.6.1 Scrape the surface of the specimen with a putty knife, press it "firmly" and trim the surface.
7.6.2 Place the specimen on its side as early as possible (when the specimen is not deformed) and remove the anti-adhesive backing material. Note that the block should remain in position during the curing period.
7.7 Curing of the specimen
The specimens are cured under standard conditions for 28 d or according to the curing conditions provided by the product supplier.
8 Test procedure
8.1 Number of specimens
Three specimens shall be tested per sealant sample.
8.2 Tensile-compression cycle
A single tensile-compression cycle is approximately 7 d (see 8.3a) to 8.3h).
During each cycle, the specimen is first compressed to the specified size and exposed to the accelerated ageing chamber for 3d; then the specimen is removed and stretched to the specified size within 2h (see GB/T 13477.8), and then the specimen stretched to the specified size is exposed to the accelerated ageing chamber for 4d.
8.3 Test procedure
9 Results and evaluation
9.1 Test results
9.1.1 At the end of each cycle, the specimen is removed and the surface condition (bonding or cohesion damage) is inspected and recorded.
9.1.2 When the back of the specimen is illuminated, the specimen is destroyed when light transmission occurs f bonding or cohesion damage>.
9.1.3 Due to the presence of stress concentrations near the end of the specimen, any bond or cohesion damage observed within a volume of 2 mm x 12 mm x 12 mm at one or both ends of the specimen during preparation and testing should not be counted as damage (see Figure 4).
9.2 Evaluation of results
9.2.1 The maximum number of cycles when all three specimens are free of damage is the corresponding level of the durability class. Also describe the surface condition of the specimen in accordance with GB/T41745.
9.2.2 If more than one specimen is damaged in the first four cycles, the test is finished; if one specimen is damaged, three specimens are re-prepared and the test is repeated once, and the final result is based on the results of the repeated test. The results shall be evaluated in accordance with 9.2.1.
9.2.3 If damage occurs after 4 cycles, the test is terminated. The results are evaluated in accordance with 9.2.1.
10 Test report
The test report contains the following information;
a) the number of this document
b) the name of the laboratory and the date of the test
c) Name, colour, type and batch number of the sample
d) Substrate used for the test
e) primer information; f) curing conditions of the specimen
g) Tensile-compression range (%) and displacement class
h) ageing conditions
(i) Record of bonding or cohesive damage (light transmission) of the specimen after each tensile-compression cycle.
(j) durability class of the specimen
k) description of the surface condition of the specimen; any deviation from this document.
Appendix A (informative) List of cross-references between this document and ISO 19862:2015 for structure numbering
Appendix B (Informative) List of technical differences between this document and ISO 19862:2015 and their causes
Bibliography
1 Scope
2 Normative references
3 Terms and definitions
4 Overview
5 Equipment and materials
6 General rules for testing
7 Specimen preparation
8 Test procedure
9 Results and evaluation
10 Test report
Appendix A (informative) List of cross-references between this document and ISO 19862:2015 for structure numbering
Appendix B (Informative) List of technical differences between this document and ISO 19862:2015 and their causes
Bibliography
