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1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure Interior GMW14236 Determination of the Release of Formaldehyde from Molded Parts for the Vehicle Interior Copyright 2006 General Motors Corporation All Rights Reserved June 2006 Originating Department: North American Engineering Standards Page 1 of 4 1
2、 Scope This test method describes a measuring process for determining the release of formaldehyde from moulded parts for the vehicle interior. The test method was elaborated with reference to VDA 275. Note: Nothing in the specification supersedes applicable laws and regulations unless specific exemp
3、tion has been obtained. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Principle. For this test, pieces of a particular mass and dimension are fastened above demineralized water in a sealed 1- litre polyethylene bottle and st
4、ored at a constant temperature for a specified length of time. Afterwards, the bottles are cooled and the formaldehyde absorbed in the demineralized water is determined. The quantity of formaldehyde is ascertained as a proportion of the dry weight (g/g) of the test piece. The concentration of formal
5、dehyde is determined by photometric analysis using the acetylacetone method. In an aqueous solution, formaldehyde reacts with acetylacetone in the presence of ammonium ions to become 3.5-diacetyl-1.4- dihydrolutidine (DDL). The resulting colour complex is yellow with maximum absorption at a waveleng
6、th of 412 nm. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ISO 16979 VDA 275 2.2 GM Standards/Specifications. None 3 Test Equipment 3.1 Test Apparatus. 3.1.1 Precision weighing device with scale gradation 1 mg
7、. 3.1.2 Air circulating oven capable of maintaining the required temperature to within 2C. 3.1.3 Spectrophotometer capable of measuring absorbance in the region of 412 nm. 3.1.4 One (1) liter (L) polyethylene bottle with hook implement integrated in the cover (see Figure 1). 3.2 Reagents. 3.2.1 Acet
8、ylacetone (analytical grade). 3.2.2 Ammonium acetate (analytical grade). 3.2.3 Iodine solution (I2), concentration = 0.05 mol/L. 3.2.4 Sodium thiosulphate (Na2S2O3) concentration = 0.1 mol/L. 3.2.5 Caustic soda solution (NaOH) concentration = 1 mol/L. 3.2.6 Sulphuric acid (H2SO4) concentration = 1 m
9、ol/L. 3.2.7 Starch solution concentration 1% m/m. 3.2.8 Formaldehyde solution (analytical grade) 37%. 4 Test Pieces and Number of Test Pieces 4.1 Taking of Test Pieces. The test pieces shall be taken from suitable and representative points spread evenly across the width of the moulded part. They mus
10、t be taken 50 mm from the edge of the moulded part. 4.2 The size of each test piece equals 40 mm x 100 mm x thickness. If samples of these dimensions cannot be taken due to the size of the moulded part, or if the distance of 50 mm to the edge of the part cannot be kept, this test may also be perform
11、ed using smaller test pieces. Here, care must be taken to ensure that all the edges of test pieces are freshly cut. To fasten the test piece, a hole corresponding to the diameter of the hook is made in its centre, 10 mm from the upper edge. At least three samples must be taken from each moulded part
12、. Two (2) parts are used for determining formaldehyde and one part is used to determine the moisture content. Copyright GM Worldwide Provided by IHS under license with GMW Licensee=HP Monitoring/1111111164 Not for Resale, 07/27/2009 04:10:44 MDTNo reproduction or networking permitted without license
13、 from IHS -,-,- GMW14236 GM WORLDWIDE ENGINEERING STANDARDS Copyright 2006 General Motors Corporation All Rights Reserved Page 2 of 4 June 2006 If the determined release of formaldehyde 75% of the limiting value, a further determination shall be carried out. 4.3 If testing of the test piece cannot t
14、ake place immediately, they must be stored in cool, air-tight conditions with a minimal air volume. Storage time must not exceed 5 days. 5 Procedure 5.1 Determining the Moisture Content. The moisture content is determined in accordance with ISO 16979. 5.2 Determining the Release of Formaldehyde. 5.2
15、.1 Before the analysis commences, the test pieces are weighed on the analyzing balance to 0.01 g. 50 ml aliquotes of demineralized water are pipetted into each of the 1-litre polyethylene bottles. Once the test piece has been attached to the hook, the bottle is sealed and stored for 3 hours 15 minut
16、es in a heating cabinet at +60 3C. When the test time is up, the containers are removed from the heating cabinet. After being left to stand at +23 5C for 60 10 minutes, the samples are taken out of the bottles. A blank test shall be run without test piece present. Figure 1: Structure of Test Apparat
17、us 5.2.2 Photometric Determination of the Concentration of Formaldehyde in the Aqueous Solution. 5.2.2.1 Reagents. 5.2.2.1.1 Acetylacetone Solution. Two 2 ml of acetylacetone is pipetted into a 500 ml measuring flask, made up to 500 ml with demineralized water and shaken hard. 5.2.2.1.2 Ammonium Ace
18、tate Solution. 100 g of ammonium acetate are measured out in a 500 ml- metering flask, dissolved in demineralized water and topped up to 500 ml. 5.2.2.2 Procedure. 10 ml of the aqueous solution resulting from the process described in 5.2.1 is transferred to a wide-necked, 50 ml Erlenmeyer flask with
19、 a ground surface, along with 10 ml of acetylacetone solution and 10 ml of ammonium acetate solution. The wide-necked Erlenmeyer flask is sealed, shaken and heated in a +40 3C water bath for 15 minutes. The above steps are then repeated using 10 ml quantities of freshly prepared calibrating solution
20、s (see sections 5.2.3.1 and 5.2.3.2). After a cooling period of one hour away from the light, the absorbance of the solution resulting from processing of the test piece (as described above), is measured at 412 nm against demineralized water using the spectrophotometer. 5.2.3 Calibration. 5.2.3.1 Sta
21、ndard Solution. The calibrating curve shall be produced by means of a formaldehyde standard solution, the formaldehyde concentration of which is determined by means of iodometric titration. Approximately 0.5 g of formaldehyde solution (concentration: 35 to 40%) shall be dissolved in demineralized wa
22、ter in a 500 ml measuring flask and topped up to the mark. Copyright GM Worldwide Provided by IHS under license with GMW Licensee=HP Monitoring/1111111164 Not for Resale, 07/27/2009 04:10:44 MDTNo reproduction or networking permitted without license from IHS -,-,- GM WORLDWIDE ENGINEERING STANDARDS
23、GMW14236 Copyright 2006 General Motors Corporation All Rights Reserved June 2006 Page 3 of 4 The exact formaldehyde concentration shall be determined as follows: 20 ml of the formaldehyde standard solution shall be mixed with 25 ml of iodine solution and 10 ml of caustic soda solution. The mixture s
24、hall be left to stand for 15 minutes away from the light, then 15 ml of sulfuric acid shall be added. Back titration of the surplus iodine is performed with the thiosulfate solution. Shortly before the end of titration, a few drops of starch solution shall be added as an indicator. Parallel to the a
25、bove test, a blank test shall be performed using 20 ml of demineralized water. The formaldehyde content shall be calculated as follows: c(HCHO) = (V0-V) x 1.5 x 1000/20 c(HCHO) = Formaldehyde concentration in mg/l V0 = Volume of thiosulfate solution for the blank test in ml V = Volume of thiosulfate
26、 solution in ml Remarks: 1 ml 0.1 mol/l of thiosulfate solution corresponds to 1 ml 0.05 mol/l of iodine solution and 1.5 mg of formaldehyde. 5.2.3.2 Calibrating Solution. Absorbance cell thickness: 1 cm. The calibrating solution shall have a concentration by mass of 15 g formaldehyde/ml. Using a bu
27、rette, the required volume of standard solution shall be poured into a 500 ml measuring flask and topped up to the mark with demineralized water. 5.2.3.3 Determining the Calibrating Curve. Absorbance cell thickness: 1 cm. From the calibrating solution, standards shall be produced the formaldehyde co
28、ncentration of which shall lie between 0 and 15 g/ml: The quantities 5, 10, 20, 50 and 100 ml shall each be pipetted into a 100 ml measuring flask and topped up to the mark with demineralized water. 10 ml of each dilution and also 10 ml of demineralized water (blank test) shall undergo photometric a
29、nalysis using the method described in section 5.2.2. The gradient of the calibrating curve and correlation factor shall be arithmetically calculated by means of linear regression. For the purpose of graphic representation, the measured absorbance values can be plotted against the formaldehyde concen
30、tration on graph paper graded in millimeters. For absorbance values smaller than 0.10, a calibrating solution and a calibrating curve shall be produced for a greater, absorbance cell thickness, e.g., 5 cm. 5.2.3.4 Calibrating Solution. Absorbance Cell Thickness: 5 cm. The calibrating solution shall
31、have a concentration by mass of 3 g formaldehyde/ml. Using a burette, the required volume of standard solution shall be poured into a 500 ml measuring flask and topped up to the mark with demineralized water. 5.2.3.5 Determining the Calibrating Curve. Absorbance cell thickness: 5 cm. From the calibr
32、ating solution, standards shall be produced the formaldehyde concentration of which shall lie between 0 and 3 g/ml: The quantities 5, 10, 20, 50 and 100 ml shall each be pipetted into a 100 ml measuring flask and topped up to the mark with demineralized water. 10 ml of each dilution and 10 ml of dem
33、ineralized water (blank test) shall undergo photometric analysis using the method described in clause 5.2.2. The gradient of the calibrating curve and correlation factor shall be arithmetically calculated by means of linear regression. For the purpose of graphic representation, the measured absorban
34、ce values can be plotted against the formaldehyde concentration on graph paper graded in millimeters. 6 Evaluation and Rating 6.1 Determination of Moisture Content. The moisture content H of the moulded part in % is derived from the following formula: H = (m1/m0 - 1) * 100% Here: m1 = is the mass of
35、 the test piece in gram before drying m0 = is the mass of the test piece in gram after drying The mass constancy is obtained, if the results of two successive tests dont deviate more than 1% from one another. 6.2 Calculating the Release of Formaldehyde. The released quantity of formaldehyde referred
36、 to the dry corrected weight shall be calculated as follows: Copyright GM Worldwide Provided by IHS under license with GMW Licensee=HP Monitoring/1111111164 Not for Resale, 07/27/2009 04:10:44 MDTNo reproduction or networking permitted without license from IHS -,-,- GMW14236 GM WORLDWIDE ENGINEERING
37、 STANDARDS Copyright 2006 General Motors Corporation All Rights Reserved Page 4 of 4 June 2006 Calculating in g/g: (AA ) f V (100H) m 1000 Fg HCHO / g abs.dry test SB + = piece AS Absorbance value of solution resulting from test piece AB Absorbance value of blank test solution. f Gradient of calibra
38、tion function in g/ml per absorbance. m Mass of the test piece in g H Moisture content of the test material in percent V Volume of the absorber solution (50 ml) F Factor for calculating the result of the analysis in g (g/g); F = 10 abs.dry Absolutely dry test material 7 Report 7.1 The formaldehyde c
39、oncentration shall be expressed as the average value of two or three determination in g/g and referred to this test method. 7.2 Test Conditions. Deviations from the conditions of this test method (e.g., storage, temperature, time etc.) shall have been agreed upon. This shall be specified on part dra
40、wings, material specifications etc. and shall be indicated in all test certificates, reports etc. 8 Safety This method may involve hazardous materials, operations, and equipment. This method does not propose to address all the safety problems associated with its use. It is the responsibility of the
41、user of the method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 9 Notes 7.1 Glossary. Not applicable. 7.2 Acronyms, Abbreviations, and Symbols. Not applicable. 10 Coding System This standard shall be referenced in other
42、documents, drawings, VTS, CTS, etc. as follows: Test to GMW14236 11 Release and Revisions 11.1 Release. This standard originated in July 2005, replacing GME60271. It was first approved by Materials Engineering in May 2006. It was first published in June 2006. Copyright GM Worldwide Provided by IHS under license with GMW Licensee=HP Monitoring/1111111164 Not for Resale, 07/27/2009 04:10:44 MDTNo reproduction or networking permitted without license from IHS -,-,-