ASTM D4795-1994(2003) Standard Test Method for Nitrogen Content of Soluble Nitrocellulose&8212 Alternative Method《可溶行硝化纤维素中氮含量的标准试验方法 交替法》.pdf
《ASTM D4795-1994(2003) Standard Test Method for Nitrogen Content of Soluble Nitrocellulose&8212 Alternative Method《可溶行硝化纤维素中氮含量的标准试验方法 交替法》.pdf》由会员分享,可在线阅读,更多相关《ASTM D4795-1994(2003) Standard Test Method for Nitrogen Content of Soluble Nitrocellulose&8212 Alternative Method《可溶行硝化纤维素中氮含量的标准试验方法 交替法》.pdf(3页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D 4795 94 (Reapproved 2003)Standard Test Method forNitrogen Content of Soluble NitrocelluloseAlternativeMethod1This standard is issued under the fixed designation D 4795; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 Test Methods D 301 for measuring nitrogen content innitrocellulose by nitrometer are the accepted standa
3、rd. How-ever, the glassware is specialized and the precision is depen-dent on the development of a high level of skill by the operator.The ferrous-sulfate titration of nitrate is a classical procedure.By controlling critical variables and automating the actualtitration, precision equivalent to the n
4、itrometer can be achievedwith nitrocellulose. This test method describes such a proce-dure.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, ass
5、ociated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:D 301 Test
6、Methods for Soluble Cellulose Nitrate2D 1193 Specification for Reagent Water33. Summary of Test Method3.1 A weighed specimen of nitrocellulose is dissolved insulfuric acid and titrated automatically with ferrous sulfate.The nitrogen content of the specimen is calculated using theequivalence factor o
7、f the ferrous sulfate.4. Significance and Use4.1 This test method provides a simpler means for measur-ing the nitrogen content of nitrocellulose than the nitrometerdescribed in Test Methods D 301. Under controlled conditions,the procedure described is capable of results equivalent tothose obtained b
8、y the nitrometer.5. Interferences5.1 The presence of moisture (or other volatile components)in the specimen will affect results. It is recommended that onlythoroughly dry specimens be used.5.2 Temperature rise must be controlled during the titration.The cooling bath provides that control. However, i
9、f the rate oftitrant addition is too fast, temperature may rise out of control.Results may then be erratic. Adherence to the procedure willavoid temperature excursions. For optimum system efficiency,room temperature should be maintained at 23 6 2C.5.3 The strength of the sulfuric acid used to dissol
10、ve thespecimen is very important. Too low an acid strength slows therate of solution which, in turn, causes titrations to be abnor-mally slow. Results then become erratic.6. Apparatus6.1 Acid Bottle Safety Dispenser.6.2 Brinkman 20 Titration System, or equivalent, with 25mL amber buret:6.2.1 Electro
11、de, platinum.6.2.2 Electrode, glass.6.3 Desiccator, with drying agent.6.4 Weighing bottles, 12-mL capacity, aluminum (preferred)or glass.6.5 Analytical Balance, accurate to 60.1 mg.6.6 Ovens135C, for drying standards, and 100C, fordrying specimens, having unexposed heating elements and thedoor latch
12、 removed.6.7 Circulating Unit, for chilled water, 5 6 2C.6.8 Blender, with 0.25-L (8-oz) blender jar.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.36 on Cellulose and Cel
13、lulose Derivatives.Current edition approved May 10, 2003. Published June 2003. Originallyapproved in 1988. Last previous edition approved in 1994 as D 4795 94 (1998).2Annual Book of ASTM Standards, Vol 06.03.3Annual Book of ASTM Standards, Vol 11.01.1Copyright ASTM International, 100 Barr Harbor Dri
14、ve, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the America
15、n Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water
16、shall be understood to mean reagent water as definedby Type III of Specification D 1193.7.3 Sulfuric Acid (H2SO4)95to98%.7.4 Ferrous Sulfate SolutionDissolve 350 g of ferroussulfate crystals (FeSO4) in 1000 mL of distilled water. Add1000 mL of 1+1 H2SO4solution. Makes 2 L.7.5 Potassium Nitrate (KNO3
17、) Standard or an equivalentnitrate primary standard.7.6 Nitrocellulose StandardA sample with a known nitro-gen value or other known organic nitrate.8. Hazards8.1 Since the sample of nitrocellulose must be dried, it isimperative that care be exercised in storage, handling, anddisposal. Dry nitrocellu
18、lose is extremely flammable. Refer tothe Procedure section for Drying Samples of Test MethodsD 301.8.2 Strong sulfuric acid used as the solvent for the specimencan burn the skin. The ferrous sulfate titrant is also stronglyacidic. Take proper precautions to protect the operator and theequipment.8.3
19、To prevent burns from acid dripping off the electrodesand dispenser tip, always wipe the electrodes and dispenser tipwith a tissue before reaching under them to retrieve a beaker.9. Preparation of Apparatus9.1 If the system has been down for at least 8 h, purge thesystem with 40 mL of ferrous sulfat
20、e solution.10. Calibration and Standardization10.1 Weigh a sample bottle containing 0.5000 6 0.05 g ofKNO3that has been dried in a 135C oven for a minimum of4 h and stored in a dessicator. If KNO3has been out of the ovenfor4hormore, redry in a 135C oven for a minimum of 2 h.(Nitrocellulose specimens
21、 are dried in a 100C oven for aminimum of 1 h. If out of the oven more than 2 h, redry for12h.) Turn on the pump of the chilled water circulator to startwater flowing through the cooling bath.10.2 Place the magnetic stirring bar into a dry 250-mLbeaker and fill the beaker with 150 mL of H2SO4(20 6 2
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