橡胶轮胎中氮素含量检测方案(定氮仪)

APPLICATION NOTE N DETERMINATION IN TYRE RUBBERDUMAS COMBUSTION METHOD C-D-001-2013/A1 N Determination in Tyre Rubberaccording to Dumas combustion method Reference： ISO TC 45/SC 2 N2116 Rubber， raw， latex-Determination of nitrogen content by DumasCombustion method Tested with VELP Scientifica NDA 701 Dumas Nitrogen Analyzer (Code F30800070) Introduction Modern pneumatic tyres are made by synthetic or natural rubber， fabric and metal wires with chemicalcompounds. Pneumatic tyres are used on many types of vehicles， including cars， bicycles， motorcycles，trucks， earthmovers， and aircraft. For tyre manufacturers it is important to determine the content of nitrogenpresent in the constituent mixture because a high presence of nitrogen adversely affects the performance ofthe tyre， increasing the incidence of premature failure of it. Nitrogen Determination in Tyre Rubber The Dumas method starts with a combustion furnace (CF) toburn the sample， obtaining elemental compounds. Water is removed by a first physical trap (WT1 -DriStepTM)，placed after the combustion， and a second chemical one(WT2). Between the two， the elemental substances passedthrough a reduction furnace (RF). The auto-regenerative CO2 adsorbers (CO2) let pass only theelementallnitrogen thatisdetectedbythe LoGas TMinnovative Thermal Conductivity Detector (TCD) withnorequirement for a reference gas. The NDA 701 is controlled via PC through the intuitiveDUMASoftTM. NDA 701 Preliminary Operations (daily) Follow the operating manual to start the NDA 701 and check that the following parameters are set： Temperature Combustion reactor (Code A00000158)： 1030°C Temperature Reduction reactor (Code A00000226)： 650°C Flow rate MFC1 He： 195 ml/min Flow rate MFC2 He： 200 ml/min Condition the system by testing 2 EDTA standard (Code A00000149) and 3 to 5 empty tin foils (CodeA00000153) as Check up. Verify the calibration curve with one or more tests as Standard by testing the same standard used for thecurve creation. Sample Preparation Cut in pieces the rubber from a car tyre， clean it from fiber and metal parts. Freeze the cut rubber (around -10℃) in order to enhancing the solidification and obtain a better homogenization with a grinder (particle sizearound 2 mm) Weigh around 80 mg of tyre rubber directly in a tin foil placed on the balance. Close carefully the tin foil by hands，obtaining a capsule. Load it into the autosampler. Analysis Procedure Fill the following fields in the database： Sample name， Weight， Method， Sample type， Calibrationnumber. The TYRE RUBBER method shows the following parameters. Protein factor： none O2 flow rate： 400 ml/min O2 factor： 1.8 ml/mg Press to start the analysis. Analysis time： from 3 minutes for one run. Typical Results on Tyre Rubber Sample quantity (mg) Nitrogen % 79.10 0.346 80.00 0.348 79.50 0.332 79.00 0.341 79.40 0.356 79.10 0.340 79.30 0.340 80.00 0.343 79.00 0.342 80.80 0.349 Average ± SD% 0.344±0.006 RSD%* 1.885 Nitrogen Expected Value： 0.2-0.5% (*) RSD% =(Standard Deviation * 100) / Average Conclusion The obtained results are reliable and in accordance with the expected value. The nitrogen content of tyrerubber is in accordance with the specifications of the substance (0.2

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