GB/T 42923-2023 Glass-fibre-reinforced plastic products - Determination of fibre length
1 Scope
This standard specifies a method of determining the length of the fibres present in a fibre- reinforced product.
This standard is applicable to discontinuous glass fiber reinforced thermoplastic moulding materials and to moulded parts. The fibres length is less than or equal to 7.5 mm prior to incorporation in the moulding material and moulding and less than 1mm after that.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments)applies.
ISO 472 Plastics - Vocabulary
Note: GB/T 2035-2008 Terms and definitions for plastics (ISO 472: 1999, IDT)
ISO 1172 Textile-glass-reinforced plastics - Prepregs, moulding compounds and laminates - Determination of the textile-glass and mineral-filler content - Calcination methods
Note: GB/T 2577-2005 Test method for resin content of glass fiber reinforced plastics (ISO1172:1996, MOD)
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 472 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
- ISO Online browsing platform: available at https://www.iso.org/obp
- IEC Electropedia : available at http://www.electropedia.org/
4 Principle
The fibres are separated from the reinforced polymer and their length measured from a magnified image on a screen.
5 Apparatus
5.1 Muffle furnace, capable of maintaining a temperature of 625℃±25℃
5.2 Crystallizing dish, diameter 80 mm to 110 mm.
5.3 Uitrasonic device.
Note: A basic ultrasonic device, like those used in laboratories for cleaning purposes, has been found suitable.
5.4 Microscope or stereoscope, with fixed or variable magnification factors, equipped with a video camera, giving at least ×50 magnification.
5.5 Image acquisition device, that enables the image to be displayed on a TV monitor.
5.6 Reference micrometer, to calibrate the images at the selected magnification.
5.7 Data-processing equipment, with suitable image analysis software.
5.8 Drying oven, capable of maintaining a temperature of 130℃±5℃.
5.9 Test accessories
Crucibles, evaporation dishes, spatulas, glass microscope slides)
6 Procedure
6.1 Preparation of the test specimen
From the sample to be examined, take the quantity of material necessary to obtain a concentration of fibres such that each image displayed on the screen contains a hundred or so fibres. This quantity will depend on the fibre content of the material and on the test conditions, in particular on the diameter of the crystallizing dish (the water depth in the crystallizing dish does not have any influence on the concentration of the fibres deposited on the glass slide, as the fibres precipitate in a horizontal plane).
Example: For a 30% glass-fibre-reinforced polyamide, around 0.006 g of material are required when a 90 mm diameter crystallizing dish is used
Note 1: This assumes that the fibre length is less than 1 mm.
Calcine the material at 625℃ in accordance with ISO 1172 for 1 h 30 min and allow to cool.
Note 2: The ash obtained is mainly made up of glass fibres and possibly also mineral fllers. The fibres are very fragile and all subsequent handling must be conducted with extreme caution in order not to break them and therefore invalidate the results.
Note 3: After cooling, transfer the ash in the crucible to watch glasses.
Note 4: Select the appropriate material quality and size, and extend the calcination time appropriately if the material is not sufficiently calcined.
Place a previously degreased glass microscope slide in a crystallizing dish (5.2) and pour in a quantity of demineralized water (containing a small amount of surfactant) just sufficient to cover the slide. The quantity of water is limited in order to avoid the formation of convection currents during subsequent evaporation, which lead to a selection of the fibres on the basis of their mass and therefore of their size.
Pour the ash into the crystallizing dish prepared as described above (or transfer a sufficient quantity on the tip of a spatula).
Place the crystallizing dish containing the ash in the ultrasonic device in order to disperse the fibres without any mechanical action. The time required for this dispersion is in the region of a few seconds to 1 min.
Then place the crystallizing dish in an oven (5.8) preheated to 130℃ and leave it there for approximately 1h, in order to eliminate the water. Allow to cool down. This procedure may be omitted if heating tends to cause the fibres to stick together.
Place the crystallizing dish beside the microscope or stereoscope (5.4). Take the slide covered with fibres and place it under the microscope or stereoscope lens. If necessary, wipe off any fibres present on the underside of the slide.
6.2 Calibration
Calibrate the system using a reference gauge; a 1 mm or 1.5 mm length micrometric glass slide is recommended.
Calibration can be carried out by measuring the length of the reference gauge, pointing to the two ends as would be done when measuring the lengths the fibres, and comparing the reading with the gauge length. The recommended tolerance should be 0.01 mm.
Calibrate the microscope as frequently as necessary.
6.3 Examination and measurements
The fibres are examined directly, without microscope cover glass or mounting fluid, in reflected or transmitted light, in the light-field or dark-field (annular illumination) mode.
Adjust the overall magnification chain (optics and projection) in order to obtain on the screen an image magnified between 50 and 100 times. The magnification shall be such that the whole lengths of 100±20 fibres appear on the screen.
Measure manually the lengths of all the complete fibres appearing on the screen by clicking with the mouse on the ends of each fibre. Measure 100±20 fibres in this way from each of three images, for a total of 300±60 fibres.
Note 1: This manual measurement method can be replaced by a semi-automatic method. However, it must be realized that such methods are biased towards the smaller fibres and that the results obtained will therefore be
Note 2: While outside the scope of this method, if longer fibres up to 5mm in length are measured, the magnification can be reduced to as little as 15, provided the quality of the optical system is good enough to permit satisfactory measurement.
Note 3: If the measurement results of the three images are quite different, increase the number of fibers.
Standard
GB/T 42923-2023 Glass-fibre-reinforced plastic products―Determination of fibre length (English Version)
Standard No.
GB/T 42923-2023
Status
valid
Language
English
File Format
PDF
Word Count
5500 words
Price(USD)
160.0
Implemented on
2024-3-1
Delivery
via email in 1~3 business day
Detail of GB/T 42923-2023
Standard No.
GB/T 42923-2023
English Name
Glass-fibre-reinforced plastic products―Determination of fibre length
GB/T 42923-2023 Glass-fibre-reinforced plastic products - Determination of fibre length
1 Scope
This standard specifies a method of determining the length of the fibres present in a fibre- reinforced product.
This standard is applicable to discontinuous glass fiber reinforced thermoplastic moulding materials and to moulded parts. The fibres length is less than or equal to 7.5 mm prior to incorporation in the moulding material and moulding and less than 1mm after that.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments)applies.
ISO 472 Plastics - Vocabulary
Note: GB/T 2035-2008 Terms and definitions for plastics (ISO 472: 1999, IDT)
ISO 1172 Textile-glass-reinforced plastics - Prepregs, moulding compounds and laminates - Determination of the textile-glass and mineral-filler content - Calcination methods
Note: GB/T 2577-2005 Test method for resin content of glass fiber reinforced plastics (ISO1172:1996, MOD)
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 472 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
- ISO Online browsing platform: available at https://www.iso.org/obp
- IEC Electropedia : available at http://www.electropedia.org/
4 Principle
The fibres are separated from the reinforced polymer and their length measured from a magnified image on a screen.
5 Apparatus
5.1 Muffle furnace, capable of maintaining a temperature of 625℃±25℃
5.2 Crystallizing dish, diameter 80 mm to 110 mm.
5.3 Uitrasonic device.
Note: A basic ultrasonic device, like those used in laboratories for cleaning purposes, has been found suitable.
5.4 Microscope or stereoscope, with fixed or variable magnification factors, equipped with a video camera, giving at least ×50 magnification.
5.5 Image acquisition device, that enables the image to be displayed on a TV monitor.
5.6 Reference micrometer, to calibrate the images at the selected magnification.
5.7 Data-processing equipment, with suitable image analysis software.
5.8 Drying oven, capable of maintaining a temperature of 130℃±5℃.
5.9 Test accessories
Crucibles, evaporation dishes, spatulas, glass microscope slides)
6 Procedure
6.1 Preparation of the test specimen
From the sample to be examined, take the quantity of material necessary to obtain a concentration of fibres such that each image displayed on the screen contains a hundred or so fibres. This quantity will depend on the fibre content of the material and on the test conditions, in particular on the diameter of the crystallizing dish (the water depth in the crystallizing dish does not have any influence on the concentration of the fibres deposited on the glass slide, as the fibres precipitate in a horizontal plane).
Example: For a 30% glass-fibre-reinforced polyamide, around 0.006 g of material are required when a 90 mm diameter crystallizing dish is used
Note 1: This assumes that the fibre length is less than 1 mm.
Calcine the material at 625℃ in accordance with ISO 1172 for 1 h 30 min and allow to cool.
Note 2: The ash obtained is mainly made up of glass fibres and possibly also mineral fllers. The fibres are very fragile and all subsequent handling must be conducted with extreme caution in order not to break them and therefore invalidate the results.
Note 3: After cooling, transfer the ash in the crucible to watch glasses.
Note 4: Select the appropriate material quality and size, and extend the calcination time appropriately if the material is not sufficiently calcined.
Place a previously degreased glass microscope slide in a crystallizing dish (5.2) and pour in a quantity of demineralized water (containing a small amount of surfactant) just sufficient to cover the slide. The quantity of water is limited in order to avoid the formation of convection currents during subsequent evaporation, which lead to a selection of the fibres on the basis of their mass and therefore of their size.
Pour the ash into the crystallizing dish prepared as described above (or transfer a sufficient quantity on the tip of a spatula).
Place the crystallizing dish containing the ash in the ultrasonic device in order to disperse the fibres without any mechanical action. The time required for this dispersion is in the region of a few seconds to 1 min.
Then place the crystallizing dish in an oven (5.8) preheated to 130℃ and leave it there for approximately 1h, in order to eliminate the water. Allow to cool down. This procedure may be omitted if heating tends to cause the fibres to stick together.
Place the crystallizing dish beside the microscope or stereoscope (5.4). Take the slide covered with fibres and place it under the microscope or stereoscope lens. If necessary, wipe off any fibres present on the underside of the slide.
6.2 Calibration
Calibrate the system using a reference gauge; a 1 mm or 1.5 mm length micrometric glass slide is recommended.
Calibration can be carried out by measuring the length of the reference gauge, pointing to the two ends as would be done when measuring the lengths the fibres, and comparing the reading with the gauge length. The recommended tolerance should be 0.01 mm.
Calibrate the microscope as frequently as necessary.
6.3 Examination and measurements
The fibres are examined directly, without microscope cover glass or mounting fluid, in reflected or transmitted light, in the light-field or dark-field (annular illumination) mode.
Adjust the overall magnification chain (optics and projection) in order to obtain on the screen an image magnified between 50 and 100 times. The magnification shall be such that the whole lengths of 100±20 fibres appear on the screen.
Measure manually the lengths of all the complete fibres appearing on the screen by clicking with the mouse on the ends of each fibre. Measure 100±20 fibres in this way from each of three images, for a total of 300±60 fibres.
Note 1: This manual measurement method can be replaced by a semi-automatic method. However, it must be realized that such methods are biased towards the smaller fibres and that the results obtained will therefore be
Note 2: While outside the scope of this method, if longer fibres up to 5mm in length are measured, the magnification can be reduced to as little as 15, provided the quality of the optical system is good enough to permit satisfactory measurement.
Note 3: If the measurement results of the three images are quite different, increase the number of fibers.
