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ISO 11344:2016 pdf free

ISO 11344:2016 pdf free.Rubber, raw synthetic一Determination of the molecular-mass distribution of solution polymers by gel permeation chromatography
Solvent reservoir, of sufficient capacity to complete the analysis without rfilling.
NOTE A large stock of THF is needed to avoid frequent refills. Changes in the quantity of dissolved air or impurities due to addition of fresh solvent cause significant variations in the refractive index and can also affect the retention time. Air bubbles at the pump head reduce the quantity of solvent pumped (leading to errors in retention volumes and times) and can block the pump if the volume of the air bubbles reach excessive levels.
After adding fresh solvent, it takes 2 h to 3 h to obtain a stable baseline.
Agitate the solution gently on a shaker to ensure the polymer has dissolved completely and then make up to 50 cm3 with filtered THF containing BHT solution.
Shake the solution at room temperature to ensure complete dissolution and homogenization; in the case of samples with a mean molar mass of less than 700 000 g/mol, a magnetic stirrer may be used. The use of ultrasound is not permitted because of the risk of degradation. The use of heat should preferably also be avoided. Exceptions, e.g. for PVC, shall be justified in the test report.
Remove insoluble foreign matter from the injection solution by suitable methods, e.g. ultracentrifugation,filtration or membrane filtration. Even if the solution appears clear to the eye, filtration through membrane filters is always recommended. If the sample contains insoluble polymer particles,e.g. microgel, the test report shall expressly point out that the GPC results refer only to the soluble components. The appearance of such samples shall be described.
Results are acceptable if the retention time of the BHT marker is within t 30 s of the value obtained during the calibration stage (see 7.2). If this is not achieved, the columns shall be cleaned by flushing fresh solvent through them for at least 3 h and then the retention time of the BHT marker is determined again.
Should the anomalous retention time be confirmed, the system needs recalibration using the polystyrene standards (see 7.2).
The instrument software allows calculation of a great deal of information about the molecular-mass distribution (see Annex A). ISO 11344 pdf free.

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