GB/T 20102-2026Test method for determining alkali resistance of glass fiber reinforcing mesh - Exposure to a sodium hydroxide solution (English PDF)

1 Scope

This document describes the principle, instruments and reagents, samples, laboratory environment, operating procedures, and result calculation for the alkali resistance test of glass fiber mesh.

The calculation and test report provide two test methods. the conventional method and the rapid method.

This document applies to the alkali resistance testing of fiberglass mesh fabrics that require alkali resistance.

4 Principles

The tensile breaking strength of samples soaked in sodium hydroxide alkaline solution (hereinafter referred to as "alkaline solution") and samples not soaked in alkaline solution were tested respectively.

The retention rate of tensile breaking strength is calculated to characterize the alkali resistance of the glass fiber mesh.

5 Instruments and reagents

5.1 Tensile testing machine. constant rate elongation type conforming to GB/T 7689.5.

5.2 Electronic balance. scale division value not greater than 0.01g, accuracy class not lower than III.

5.3 Graduated cylinder. 1000mL, graduation value 10mL, commercially available.

5.4 Covered Container. Made of a material that does not chemically react with alkaline solutions, with a built-in sample holder, sized to allow the sample to be placed flat.

The container should be kept within the alkaline solution, ensuring the liquid level is at least 25 mm above the sample. The container lid should be sealed to prevent evaporation of water from the alkaline solution.

5.5 Heating device. capable of heating covered containers, keeping the temperature of covered containers controlled at 60°C±2°C.

5.6 Pure water. not lower than laboratory grade III water.

5.7 Sodium hydroxide. analytical grade, commercially available.

5.8 Absorbent paper. Commercially available.

6 Samples

6.1 Cut 30 sample strips from the roll, each with a width of 50mm ± 3mm and a length of 600mm ± 13mm. Of these, 15 are warp-oriented.

The specimen, i.e., the long side of the specimen strip is parallel to the warp direction of the fiberglass mesh; 15 weft specimens, i.e., the long side of the specimen strip is parallel to the fiberglass mesh.

The weft direction of the fabric.

6.2 Each sample strip should contain the same number of yarns.

6.3 Warp samples should be cut over the entire width of the fiberglass mesh, at least 100 mm from the edge, to ensure they represent different warp directions.

For yarn, the weft sample should be cut within a range of not less than 100 mm from the edge of the fiberglass mesh.

6.4 Number each test strip at both ends, ensuring the markings are clear and not damaged by the alkaline solution. Divide the test strip transversely from the middle.

The test specimens are divided into two parts. one half is used to determine the tensile breaking strength of specimens that have not been soaked in the alkaline solution, and the other half is used to determine the tensile breaking strength of specimens that have been soaked in the alkaline solution.

Tensile strength.

Note. Samples before and after soaking are from the same sample strip, which makes the samples soaked in alkaline solution directly comparable to those that have not been soaked in alkaline solution.

7 Laboratory Environment

Temperature 23°C±2°C, relative humidity 50%±10%.

8 Operating Procedures

9 Result Calculation

Calculate the retention rate of the longitudinal (or latitudinal) tensile breaking strength according to formula (1), and retain the result to one decimal place.

10 Test Report

The test report should include at least the following.

a) This document number;

b) Identify all necessary details of the fiberglass mesh being tested;

c) The number of yarns in the sample;

d) The method used (method A or method B);

e) Tensile strength retention rate of warp and weft specimens;

f) Average tensile breaking strength of meridional specimens not soaked in alkaline solution, and average tensile breaking strength of meridional specimens soaked in alkaline solution.

Average tensile strength, average tensile breaking strength of weft specimens not soaked in alkaline solution, average tensile breaking strength of weft specimens soaked in alkaline solution Average tensile strength at break;

g) Any operational details not mentioned in this document and any circumstances that may affect the test results;

h) Test date and report date.