GB/T 40911.2-2021Plastics - Poly(methyl methacrylate)sheets - Types, dimensions and characteristics - Part 2: Extruded sheets (English PDF)

1 Scope

This document specifies the requirements, test methods, inspection rules, marking, packaging, transportation and storage for extruded colorless or colored, transparent, translucent or opaque flat poly (methyl methacrylate) (PMMA) sheets.

This document applies to PMMA extruded sheets (hereinafter referred to as “sheets”)

with a thickness ranging from 0.3 mm to 20.0 mm.

This document does not apply to PMMA modified with elastomers.

2 Normative references

The following documents are normatively referenced in this document and are indispensable for its application. For dated references, only the version corresponding to that date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document.

GB/T 1033.1-2008, Plastics - Methods for determining the density of non-cellular plastics - Part 1: Immersion method liquid pycnometer method and titration method (ISO 1183-1:2004, IDT)

GB/T 1034-2008, Plastics - Determination of water absorption (ISO 62:2008, IDT)

GB/T 1040.2-2006, Plastics - Determination of tensile properties - Part 2: Test conditions for moulding and extrusion plastics (ISO 527-2:1993, IDT)

GB/T 1043.1-2008, Plastics - Determination of Charpy impact properties - Part 1:

Non-instrumented impact test (ISO 179-1:2000, IDT)

GB/T 1633-2000, Plastics - Thermoplastic materials - Determination of Vicat softening temperature (VST) (ISO 306:1994, IDT)

GB/T 1634.1-2019, Plastics - Determination of temperature of deflection under load - Part 1: General test method (ISO 75-1:2013, MOD)

GB/T 1634.2-2019, Plastics - Determination of temperature of deflection under load - Part 2: Plastics and ebonite (ISO 75-2:2013, MOD)

GB/T 2410-2008, Determination of the luminous transmittance and haze of transparent plastics

GB/T 2828.1-2012, Sampling procedures for inspection by attributes - Part 1:

Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection (ISO 2859-1:1999, IDT)

GB/T 2918-2018 Plastics - Standard atmospheres for conditioning and testing (ISO 291:2008, MOD)

GB/T 3398.2-2008, Plastics - Determination of hardness - Part 2: Rockwell hardness (ISO 2039-2:1987, IDT)

GB/T 3682.2-2018, Plastics - Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics - Part 2: Method for materials sensitive to time-temperature history and/or moisture (ISO 1133-1:2011, MOD)

GB/T 6672, Plastics film and sheeting - Determination of thickness by mechanical scanning (GB/T 6672-2001, ISO 4593:1993, IDT)

GB/T 6673, Determination of length and width of plastics film and sheeting (GB/T 6673-2001, ISO 4592:1992, IDT)

GB/T 9341, Plastics - Determination of flexural properties (GB/T 9341-2008, ISO 178:2001, IDT)

GB/T 12027, Plastics - film and sheeting - Determination of dimensional change on heating (GB/T 12027-2004, ISO 11501:1995, IDT)

GB/T 16422.2-2014, Plastics - Methods of exposure to laboratory light sources - Part 2: Xenon-arc sources (ISO 4892-2:2013, IDT)

GB/T 36800.2, Plastics - Thermomechanical analysis (TMA) - Part 2: Determination of coefficient of linear thermal expansion and glass transition temperature (GB/T 36800.2-2018, ISO 11359-2:1999, IDT)

GB/T 39691-2020, Plastics - Determination of refractive index (ISO 489:1999, MOD)

ISO 1628-6, Plastics - Determination of viscosity number and limiting viscosity number - Part 6: Methyl methacrylate polymers

ISO 2818, Plastics - Preparation of test specimens by machining

3 Terms and definitions

The following terms and definitions are applicable to this document.

6 Test methods

6.1 General

6.1.1 Standard environment for specimen state conditioning and testing Unless otherwise specified, the test specimens shall be conditioned at a temperature of (23+/-2) °C and a relative humidity of (50+/-10) % in accordance with the provisions of

GB/T 2918-2018, for not less than 48 h, and shall be tested in this environment.

The test specimen for Vicat softening temperature shall be placed at (80+/-2) °C for not less than 24 h, and then cooled to room temperature in a desiccator.

The test specimen for load deflection temperature shall be placed at (80+/-2) °C for 16 h ~ 24 h, and cooled to room temperature in a desiccator.

The measurement of dimensions of sheets shall be carried out at room temperature, but in case of dispute, it shall be measured under the conditions of temperature (23+/-2) °C and relative humidity (50+/-10) % specified in GB/T 2918-2018.

6.1.2 Preparation of test specimens Unless otherwise specified, the specimens shall be prepared in accordance with the provisions of ISO 2818. When it is necessary to process the sheets to the thickness required for a particular test method, one original surface shall remain unchanged.

6.1.3 Thickness of test specimens When the thickness of the sheet is less than the thickness of the specimen required in a particular test method, a specimen of that thickness shall be used.

6.2 Appearance Defects and their distribution shall be observed by irradiating the sheet with sunlight or a light source with a color temperature of (6 500+/-650) K and sufficient brightness.

6.3 Color Visually inspect.

6.4 Dimensions

6.4.1 length and width According to the provisions of GB/T 6673, use a measuring tool with a division value not greater than 1 mm to measure the length and width of the sheet at equal intervals along the length and width of the test specimen, and measure each test specimen at least

4 times. Calculate the width limit deviation of the recorded data according to Formula

(1), and calculate the length limit deviation according to Formula (2).

Where:

delta W - width limit deviation, in millimeters (mm);

Wmin or max - measured minimum or maximum width, in millimeters (mm);

W0 - nominal width, in millimeters (mm).

Where:

delta l - length limit deviation, in millimeters (mm);

lmin or max - measured minimum or maximum length, in millimeters (mm);

l0 - nominal length, in millimeters (mm).

6.4.2 Thickness According to the provisions of GB/T 6672, use a measuring tool with a division value not greater than 0.01 mm. Measurements shall be made at a distance not less than 10 mm from the edge of the sheet. Use the recorded data to calculate the thickness limit deviation according to Formula (3).

Where:

delta e - thickness limit deviation, in millimeters (mm);

emin or max - measured minimum or maximum thickness, in millimeters (mm);

e0 - nominal thickness, in millimeters (mm).

min or max min or max min or max

6.4.3 Diagonal difference Measure the lengths of the diagonals of the sheets respectively, and use a measuring tool with a division value not greater than 1 mm to find the difference.

6.5 Tensile property According to the provisions of GB/T 1040.2-2006, use 1B-type specimens, and the test direction is consistent with the extrusion direction of the sheet. The test speed for tensile strength and tensile strain at break shall be (5+/-1) mm/min, and the test speed for modulus of elasticity shall be (1+/-0.2) mm/min.

6.6 Charpy impact strength Test according to the provisions of GB/T 1043.1-2008/1fU. The recommended specimen size is 80 mm x 10 mm x 4 mm. Specimens with a thickness less than 4 mm shall be tested as per the original thickness of the specimen. The length direction of the specimen is consistent with the extrusion direction.

6.7 Vicat softening temperature Test according to the provisions of GB/T 1633-2000/B50. The test surface is the original extruded surface of the sheet. The thickness of the specimen is 3.0 mm ~ 6.5 mm. The specimen that is too thick shall be processed into a specimen with a thickness of 3.0 mm ~ 6.5 mm, and an original extruded surface of the sheet shall be retained.

The load is (50+/-1) N, and the heating rate is (50+/-5) °C/h. Before the test, the specimen shall be placed at (80+/-2) °C for 24 h, and then cooled to room temperature in a desiccator.

6.8 Shrinkage According to the provisions of GB/T 12027, the heating temperature is (160+/-2) °C, and the heating time is carried out according to Table 6. When the thickness of the specimen is too large, prolong the cooling time in the desiccator until the specimen is cooled to the ambient temperature.

6.9 Total light transmittance Test according to method A in GB/T 2410-2008.

6.10 Light transmittance after xenon lamp aging Measure according to GB/T 1634.1-2019 and method A in GB/T 1634.2-2019. The test surface is the original extruded surface of the sheet. Before the test, the specimen shall be placed at (80+/-2) °C for 16 h ~ 24 h, and cooled to room temperature in a desiccator.

6.16 Melt mass flow rate According to the provisions in GB/T 3682.2-2018, use the test temperature of 230 °C and the load of 3.8 kg. As for the specimen, use PMMA particles before sheet forming.

Dry the particles at (100+/-10) °C for no less than 20 minutes before the test, and carry out the test immediately after the specimen leaves the oven.

6.17 Viscosity Test according to the provisions of ISO 1628-6.

6.18 Haze Test according to the provisions of method A of GB/T 2410-2008.

6.19 Refractive index Test according to the method A of GB/T 39691-2020.

6.20 Density Test according to method A (immersion method) of GB/T 1033.1-2008.

6.21 Water absorption According to the provisions of method 1 of GB/T 1034-2008, the water temperature is (23+/-1) °C, the soaking time is (24+/-1) h, and the recommended specimen size is 50 mm x 50 mm, original thickness of the specimen.

7 Inspection rules

7.1 Batch Products are accepted in batches. The continuously produced products - of the same designation of raw material, the same length, width and thickness, the same formula, and same process - shall be one batch, not more than 1 000 pieces.

7.2 Inspection classification

7.2.1 Delivery inspection The ex-factory inspection items are appearance, dimensions and warping.

7.2.2 Type inspection The type inspection items are all items in the basic requirements. In any of the following cases, type inspection shall be carried out:

a) Trial type identification of new products or old products transferred to the factory;

b) After official production, if there are major changes in raw materials, formulas, and processes, which may affect product performance;

c) Under normal production, it shall be carried out at least once a year.

d) When production which is suspended in long term for more than half a year is resumed;

e) When the ex-factory inspection result is significantly different from the previous type inspection result.

7.3 Sampling Appearance and dimensional deviation shall follow the S-1 special inspection level on single sampling plan stipulated in GB/T 2828.1-2012, and the acceptance quality limit (AQL) is 6.5, as shown in Table 8.

7.4 Determination rules

7.4.1 Judgment of unqualified items If the inspection results of appearance and dimensional deviation meet the requirements in Table 8, judge it as qualified, otherwise judge it as unqualified.

If there are unqualified items in the basic performance test results, the double specimens shall be taken from the original batch for a re-inspection of unqualified items. If there are still unqualified test results, judge the item as unqualified.

7.4.2 Determination of a qualified batch If all performance test results are qualified, judge the batch to be qualified, otherwise, judge the batch to be unqualified.