1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2006 SAE International All rights reserved. No part of this publication m
3、ay be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org J2665 ISSUED OCT2006 SURFACE VEHICLE RECOMMENDED PRACTICE Issued 2006-10 Test Procedure to Measure the Fuel Permeability of Materials by the Cup Weight Loss Method RATIONALE Not applicable. TABLE OF CONTENTS 1. Scope
5、 1 2. References 2 3. Usefulness and Limitations. 2 4. Safety 3 5. Apparatus 3 6. Test Fuels . 4 7. Sample Preparation 4 8. Procedure 5 9. Plotting the Weight Loss with Time. 6 10. Calculation of Permeation Rate 6 11. Normalized Permeation Rate 7 12. Reporting. 7 1. SCOPE This test standard covers t
6、he procedure for measuring the permeation of fuel or fuel surrogates through test samples of elastomeric, plastic or composite materials, up to about 3 mm thick. The method involves filling a test cup with the test fluid (fuel or fuel surrogate), sealing test sample over the open end of the cup, and
7、 then placing the sealed container into an oven at the desired test temperature and measuring the weight loss over time. Permeation rates are calculated from the rate of weight loss and the exposed area of the test sample. SAE J2665 Issued OCT2006 - 2 - Standard permeation test temperatures are 40 C
8、 and 60 C. Standard test fluids are Fuel C, Fuel CE10 and Fuel CM15. Other fluids, such as Fuel CMTBE15, and other volatile liquids may be tested according to this procedure as desired (SAE J1681). The method is not applicable for measuring permeation of higher boiling materials that will not comple
9、tely evaporate from the exterior surface of the sample at the test temperature. 2. REFERENCES 2.1 Applicable Publication The following publication forms a part of this specification to the extent specified herein. Unless otherwise indicated, the latest version of SAE Publications shall apply. 2.1.1
10、SAE Publications Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J1681 Gasoline, Alcohol and Diesel Fuel Surrogates for Materials Testing SAE J2659 Test Method to Measure Fluid Permeation
11、 of Polymeric Materials by Speciation 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this document. 2.2.1 ASTM Publications Available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, Tel: 610-832-9585,
12、www.astm.org. ASTM D 814-86 Standard Test Method for Rubber Property-Vapor Transmission of Volatile Liquids ASTM E 96-95 Standard Test Methods for Water Vapor Transmission of Materials 3. USEFULNESS AND LIMITATIONS The cup method, when used in accordance with the guidelines presented in the procedur
13、e sections of this method, can be an easy, effective, and relatively inexpensive screening technique for determining the relative permeability of plastics, elastomers and composites: a. The method is useful to establish the permeation rate of a given fluid and material. b. The cup method is a useful
14、 tool for distinguishing between materials that have a significant difference in their resistance to permeation. c. It is most accurate when the test fluid is a pure liquid or a liquid mixture for which changes in composition do not significantly affect the measured permeation rate. The method does
15、have some limitations: a. The permeation rate of individual components of a fuel mixture through the test material cannot be determined; if this is desired, see SAE J2659. b. The method should be used with caution when the components of a fuel mixture have widely different permeation rates: the high
16、 permeating components can be depleted from the mixture before the test is completed. c. For low permeation rates, the weight change is small so that accuracy can be a problem. In addition, the time required to obtain measurable weight changes can be very long. SAE J2665 Issued OCT2006 - 3 - d. For
17、highly permeable materials, the rapid loss of fluid may prevent the attainment of steady state before all the fluid has permeated the test film. The fuel composition of a mixed fuel may also change significantly and possibly provide erroneous results. e. The following is a list of potential sources
18、of error that should be minimized as much as possible: Weighing accuracy Leakage around seals Fuel depletion Temperature control Film thickness variation Pin holes in films Film distortion Change in test fluid composition These sources of error should be reviewed and good experimental techniques emp
19、loyed to minimize the sources of error. Examples of these techniques are described in the method. 4. SAFETY This method is intended for measuring permeation of potentially toxic and/or flammable liquids at elevated temperatures. Each laboratory is responsible for assuring that this method is run in
20、a safe manner according to its internal safety regulations and practices. 5. APPARATUS 5.1 Permeation cups should be Thwing-Albert permeation cups (Vapometer Model 68 available from Thwing-Albert Instrument Company, 10960 Dutton Road, Philadelphia, PA 19154, website: ) (shown in Figures 1 and 2) or
21、equivalent. The permeation cups used shall be leak-tight when assembled with a blank (see 5.5). The Model 68 Thwing-Albert cups, with depth of 50.8 mm, shall be referred to as “TA” cups in this document. NOTE: If T-A cups are used, they should be modified as follows (a) the supplied neoprene gaskets
22、 replaced with FKM gaskets (see Section 5.4) and (b) the six supplied knurled head screws modified or replaced to allow for torque wrench tightening (see Sections 5.7 and 8.9). FIGURE 1 - MODIFIED THWING-ALBERT CUPS: ON THE LEFT, IT IS SHOWN DISASSEMBLED WITH RETAINER RING, SCREWS, MESH, FKM GASKETS
23、 AND CUP; ON THE RIGHT IT IS SHOWN FULLY ASSEMBLED SAE J2665 Issued OCT2006 - 4 - FIGURE 2 - EXPLODED VIEW OF THE MODIFIED THWING-ALBERT PERMEATION CUP, SHOWING THE ASSEMBLY SEQUENCE OF THE COMPONENTS 5.2 Analytical balance should be capable of measuring to 0.0001 gram (e.g., Mettler AT400 or equiva
24、lent). Balances with lower precision may be used, as long as the weight loss between measurements exceeds the precision of the balance by at least 10 times. 5.3 Explosion proof oven or similar constant temperature device capable of holding the filled cups and maintaining their temperature within 1 C
25、 of the desired test temperature. There shall be sufficient air circulation in the oven/constant temperature chamber to allow dilution and purging of the permeating fuel. 5.4 Two fluoroelastomer gaskets made from FKM. It is recommended that an FKM with a minimum fluorine content of 70% for TFE/VF2/H
26、FP polymers and a Shore A hardness of 55 to 70 be used. Nominal FKM gasket sizes for the Thwing-Albert cups are 63.5 mm by 76.2 mm by 1 and 2 mm (ID x OD x thickness) for the two gaskets. 5.5 Two metal blanks cut to an appropriate diameter to fit the permeation cups (76 mm in diameter for the Thwing
27、-Albert cups) and about 0.5 mm thick. Aluminum or stainless steel should be used. 5.6 Micrometer capable of measuring sample thickness to 0.0025 mm (0.0001 in). 5.7 Torque wrench, for tightening cup screws, capable of measuring up to 1.1 N-m (10 lbf-in) torque. 5.8 Wire mesh for external sample supp
28、ort (should be 16 mesh, gauge of 1.5 mm (1/16 in) cut to an appropriate diameter to fit the permeation cups (76 mm in diameter for the Thwing-Albert cup). 6. TEST FUELS Examples of standard test fluids (fuels and fuel surrogates) and their method of preparation are given in SAE J1681. Other fuels, s
29、uch as Fuel CM15, and other liquids may be tested according to this procedure as desired. 7. SAMPLE PREPARATION With the cup method, as with all methods for measuring the permeability of a given material or composite, there are several issues that must be addressed with respect to the preparation of
30、 the sample to be tested: SAE J2665 Issued OCT2006 - 5 - 7.1 Ideally, the sample should be fabricated by the same method as will be used to make the final part. This is to ensure the same morphology for the sample and the final part. The morphology is very important as it can effect the permeation r
31、ate. 7.2 For many plastic applications injection molded parts are used. The injection molding of very thin films may be a problem for some polymers. (1) The making of good thin films that are uniform and pinhole free by injection molding is difficult and (2) the thicker the film, the longer the requ
32、ired test time. 7.3 For materials that rely on crystallinity to provide the barrier, the sample thickness should be close to the intended use thickness. This is to ensure that the level of crystallinity is representative. 7.4 In composite constructions, the relative position of the layers should be
33、representative of the final part. 8. PROCEDURE 8.1 Die cut the sample to fit the permeation cup (76.2 mm OD for T-A cups). If the sample is a composite material, label the sample, noting which side is to be the fuel contact side. 8.2 Measure the thickness of the sample to 0.0025 mm in 5 locations (o
34、nce in each quadrant and once in the center of the sample). Average the measurements and record this value as the sample thickness (t) in mm. Measured sample thickness values must all be within 10% of the average thickness, t. 8.3 Weigh and record weight (C1) of the empty cup, sample, gasket(s), etc
35、., to the nearest 0.0001 g. 8.4 Fill the permeation cup approximately 7/8 full with the test fuel (about 150 ml for T-A cups). 8.5 Assemble two cups per material to be tested as follows: 8.5.1 Place a 1 mm FKM gasket in the groove of the cup (optional for materials with Shore A 85). 8.5.2 Place the
36、sample (fuel contact side down) on the gasket. 8.5.3 Place a 2 mm FKM gasket above the sample. 8.5.4 Position the wire mesh support above this gasket. 8.5.5 Put the cup retainer ring onto the cup. 8.5.6 Align the ring, put in the screws but do not tighten. 8.6 Record the weight (W1) of the assembled
37、 cup to the nearest 0.0001g. 8.7 Repeat steps 8.3 to 8.5 for two blank cups where the metal plate is substituted for a sample. 8.8 Place the filled sample cups in the oven, right side up for one hour in order to come to equilibrium temperature. Further loosen the screws, if necessary, to relieve any
38、 built up pressure in the cup. 8.9 Finger tighten screws in a triangle form 1,3,5 then 2,4,6. Use a torque wrench to further tighten the screws in the same order to about 0.25 Nm (2 lbf -in), then firmly tighten using a torque wrench to 0.57 to 1.1 Nm (5 to 10 lbf -in). It is suggested that the scre
39、ws be retighten after the first weighing and after 1 week. Note that if lower durometer gaskets are used than recommended in 5.4, torque levels may have to be lowered to avoid damaging the gaskets. 8.10 Weigh the samples and record weight (W2) and time. ()1112CW100WW(Eq.1) SAE J2665 Issued OCT2006 -
40、 6 - 8.11 Calculate the % weight change from Equation 1. If the weight change is greater than 5% then the weight loss on equilibration is too high and the cup assembly procedure must be restarted. 8.12 Place the samples back in the oven. If permeation is to be measured on the vapor phase, place the
41、samples right side up. If it is to be measured on the liquid phase, place the samples upside down. (Safety note: it is strongly recommended that the samples be placed in a secondary container of sufficient size to contain all of the fuel in case of a leak or spill.) 8.13 Periodically remove the samp
42、les (and blanks) from the oven and record their weight and time. Frequency of weighing depends on permeation rate with more frequent weighing required for higher permeating materials. Frequency should be between once a day and twice a week. 9. PLOTTING THE WEIGHT LOSS WITH TIME When rates of permeat
43、ion are measured, the initial performance of a material may not be the same as the eventual equilibrium value. It takes a certain amount of time for the migration of the fuel to achieve its steady-state rate after first exposure to the fuel. This is particularly true if the material relies on crysta
44、llinity to provide its barrier properties. The best way to judge whether the permeation rate has reached steady state is to plot the weight loss with time. The following outlines the steps: 9.1 Determine the average weight, B, of the blanks (B = average of B1and B2) at each measurement time and subt
45、ract from the measured sample weights. These will be called the corrected sample weights. This will correct for losses through the gasket and for weighing errors due to buoyancy and other effects. 9.2 Plot the corrected sample weights (in grams) against the sampling time (days). The sampling time sh
46、ould be in days, where day = 0 for the first corrected sample weight. 9.3 A plot such as that shown in Figure 3 should be obtained. Note that not all experiments show the fuel depletion and equilibration parts of the plot. This depends on how fast equilibration takes place and duration of the experi
47、ment. 9.4 If the plot shows a steady state linear permeation consisting of at least 10 measured consecutive points, proceed to the next section to calculate the steady state flux of the material. 10. CALCULATION OF STEADY STATE FLUX (F) The “steady state flux” of a sample is sometimes also refered t
48、o as “normalized permeation rate” or “GMD” for “grams per meter squared per day”. To be consistent with other SAE documents (SAE J2659) and general scientific convention, the term “steady state flux” will be used in this document. 10.1 To calculate the sample steady state flux, perform a linear regr
49、ession calculation using at least 10 consecutive steady state values from the data of corrected cup weights versus. time. The equilibration and fuel depletion data points must not be included (see Figure 3). SAE J2665 Issued OCT2006 - 7 - FIGURE 3 - PLOT OF CORRECTED CUP WEIGHTS AGAINST TIME, USED TO ASSESS STEADY STATE PERMEATION 10.2 A correlation coefficient (R2) of greater than 99% should be obtained. If the value
