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 2007 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 J1748 REV. SEP2007 SURFACE VEHICLE RECOMMENDED PRACTICE Issued 1998-01 Revised 2007-09 Superseding J1748 JAN1998 Methods for Determining Physical Properties of Polymeric Materials Exposed to Hydrocarbon Fuels or Thei
5、r Surrogates and Their Blends with Oxygenated Additives RATIONALE This revision is made to expand the applicability of this document to include all types of gasoline and diesel fuel types and their blends with various commercially available oxygenated additives. FOREWORD This SAE Recommended Practic
6、e is a product of the SAE Cooperative Research Program, Project Group 2. The SAE Cooperative Research Project Group 2 was formed by the Oxygenated Fuels Task Force that was composed of OEM automotive engineering executives. Their task is to identify and prioritize potential areas for pre-competitive
7、 cooperative research programs to operate under the administration of SAE. The specific scope of Project Group 2 was to develop and exchange information relative to materials and test methods for use with blends of oxygenate and gasoline. The program was operated in accordance with 1984 Cooperative
8、Research Act. This revision includes information relative to test methods for determining physical properties of polymeric materials exposed to hydrocarbon fuels or their surrogates and blends of either with oxygenated additives. 1. SCOPE This SAE Recommended Practice applies to determining worst-ca
9、se fuel or test fluid surrogate, conditioning test specimens in worst-case fuel(s)/surrogate(s) prior to testing, individual tests for properties of polymeric materials exposed to oxygenate fuel/surrogate mixtures with additives. The determination of equilibrium, as well as typical calculations are
10、also covered. 1.1 Purpose Polymeric materials are used in applications that require exposure to a variety of fluid environments. Tests to determine the effects of such exposure on material properties are well established. However, the determination of the effects on polymeric materials exposed to fu
11、els of variable blends with assorted oxygenates poses new problems. This document seeks to address those concerns by detailing changes to standard tests that make them suitable for that purpose. 2. REFERENCES 2.1 Applicable Publications The following publications form a part of the specification to
12、the extent specified herein. Unless otherwise indicated, the latest revision of SAE publications shall apply. SAE J1748 Revised SEP2007 - 2 - 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-7
13、76-4970 (outside USA), www.sae.org. SAE J1681 Gasoline, Alcohol, and Diesel Fuel Surrogates for Materials Testing SAE J1737 Test Procedure to Determine the Hydrocarbon Losses from Fuel Tubes, Hoses, Fittings, and Fuel Line Assemblies by Recirculation SAE J2659 Test Method to Measure Fluid Permeation
14、 of Polymeric Materials by Speciation SAE J2663 Test Procedure to Measure Permeation of Elastomeric Hose or Tube by Weight Loss SAE J2665 Test Procedure to Measure the Fuel Permeability of Materials by the Cup Weight Loss Method 2.1.2 ASTM Publications Available from ASTM, 100 Barr Harbor Drive, Wes
15、t Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM D 412 Test Method for Rubber Properties in Tension (ISO 37) ASTM D 413 Test Method for Rubber PropertyAdhesion to Flexible Substrates (Peel Test for Fabric Adhesion) (ISO 36) ASTM D 429 Test Methods for Rubber PropertyAdhesion to R
16、igid Substrates (Metal adhesion, Using Method A, Button) (ISO 813 or ISO 814) ASTM D 471 Test Method for Rubber PropertyEffect of Liquids (ISO 1817) ASTM D 543 Test Method for Resistance of Plastics to Chemical Reagents (No ISO Found) ASTM D 618 Practice for Conditioning Plastics and Electrical Insu
17、lating Materials for Testing, Procedure A (ISO 291) ASTM D 624 Test Method for Tear Strength of Conventional Vulcanized Rubber and Thermoplastic Elastomers (ISO 34 Part 1) ASTM D 638 Test Method for Tensile Properties of Plastics (ISO 527 Parts 1 and 2) ASTM D 790 Test Method for Flexural Properties
18、 of Unreinforced and Reinforced Plastics and Electrical Insulating Materials (ISO 178) ASTM D 991 Test Method for Rubber PropertyVolume Resistivity of Electrically Conductive and Anti- Static Products (No ISO Found) ASTM D 1053 Test Method for Rubber Property Stiffening at Low Temperatures; Flexible
19、 Polymers and Coated Fabrics (ISO 1432) ASTM D 1329 Test Method for Evaluating Rubber PropertyRetraction at Low Temperature (TR Test) (ISO 2921) ASTM D 2240 Test Method for Rubber PropertyDurometer Hardness (ISO 868) SAE J1748 Revised SEP2007 - 3 - 3. REQUIREMENTS 3.1 General A problem arises in tes
20、ting materials for use in vehicles that can run on fuels with oxygenate concentrations varying from 0 to 85% by volume. There is no single oxygenate-containing test fuel composition that can be used to evaluate the relative performance of different polymeric materials. NOTE: Polymeric materials incl
21、ude plastics and elastomers. Because polymeric materials differ in their molecular structure, the most damaging concentration of oxygenate for one material may not be the most damaging for another. This problem has necessitated the designation of a series of test fluids that can be used to compare t
22、he properties of one polymeric material in its “worst-case“ fuel with those of another polymeric material in a different “worst-case“ fuel. Nevertheless, it is desirable to reduce the total number of tests as much as possible. Therefore, a single test, using weight gain at equilibrium, has been chos
23、en to determine which fuel composition (from Table 1) exerts the greatest effect on each polymeric material. Once a polymeric materials “worst-case“ fuel has been determined, its properties will be measured after exposure to that fuel. Since the rate of diffusion in plastics (glassy polymers) can be
24、 very slow, the time required for some plastics to reach equilibrium may be quite lengthy. In the simplest cases of diffusion with polymeric materials, the behavior may be described by Ficks Law. For Fickian diffusion, the time required to attain equilibrium sorption for a polymer slab or sheet expo
25、sed to a penetrant is proportional to the square of the sample thickness. Thus, the time does not increase linearly, but exponentially, as the thickness increases. However, for plastics exposed to organic liquids, the diffusion coefficient typically is not constant, may be because of non-uniformity,
26、 boundary conditions, physical effects (burrs, nicks, folds, etc.), and swelling of the sample periphery may also occur. This leads to non-Fickian or anomalous diffusion and the effect of sample thickness on the equilibrium time is not as straightforward as for the ideal Fickian case; but, in either
27、 case, as the sample thickness increases, so does the time required to achieve sorption equilibrium. Therefore, to shorten conditioning times, sample thickness should be as small as possible and still be consistent with the requirements of the test for a particular physical property. This document c
28、onsists of procedures that are designed to evaluate the performance of polymeric materials when they are exposed to variable oxygenate content fuels. The first part of this document addresses the determination of the worst-case fuel. The second part contains the procedure for conditioning actual tes
29、t specimens in fuel, prior to measuring their physical properties. Finally, the third part details the test methods for evaluating polymeric materials for use in oxygenate fuels. The methodology presented is general enough that it can be extended to determine the physical properties of polymeric mat
30、erials in gasoline mixtures with most oxygenate additives such as methanol, ethanol, MTBE, ETBE, TAME, EAME, etc., or Diesel fuel with bio-diesel additives (Fatty Acid Methyl Esters or FAME). These additives are not to be used above the maximum regulated percent of the specific additive. 4. DETERMIN
31、ING WORST-CASE FUEL 4.1 Equilibrium Weight Increase To compare the extent of polymer swelling by the test fluids given in SAE J1681 paragraph 7.1.4, the polymeric material must be allowed to reach equilibrium with each fuel. Thus, the samples will be immersed in the test fuels until they attain a co
32、nstant weight, as set forth in Appendix A. SAE J1748 Revised SEP2007 - 4 - 4.1.1 Sample Preparation To reduce the amount of time required to complete the test, plastic samples used for this procedure will be thin films produced under a nitrogen blanket by hot-plate forming or other similar method. N
33、ote should be taken that the effect of fuel on very thin hot-plate formed films can vary significantly from the effect of fuel mixture on injection molded, or extruded specimens. Samples will have a minimum surface area of 12 cm2and will be made as thin as possible. Thicker specimens can be used but
34、 they will require much longer equilibration times. After thirty test specimens have been marked for identification with an engraver or punch, precondition them at 23 C 2 C and 50% 5% relative humidity for a minimum of 40 hours according to ASTM D 618, Procedure A. For rubber, mark twenty-five ASTM
35、D 471 volume change test specimens with a punch, for identification. 4.1.2 Conditioning the Samples Weigh the specimens individually, in grams, to 4 decimal places. Place 6 plastic specimens (only 5 for elastomers) into each of 6 glass vessels furnished with a reflux apparatus, as specified in ASTM
36、D 543, and equipped with a calcium sulfate drying tube. The sixth, specially marked plastic sample is to be used to evaluate long-term chemical effects on the plastic and should not be removed from the hot fuel when the other 5 samples are weighed. Samples should be separated using stainless steel w
37、ire and glass beads according to ASTM D 471. Fill each vessel with a different oxygenate blend test fuel such that all specimens are completely submerged. Fuel formulations are provided in SAE J1681. Allow at least 1 cm of fuel above the plastic samples to compensate for any evaporation. For elastom
38、ers, allow at least 3 cm fuel above the samples to compensate for swelling as well as evaporation. Using a water or sand bath, heat the test fuel uniformly in the vessel to 55 C 2 C. Do not use heating mantles or hot plates. For elastomers, replace the test solution daily for the first three days an
39、d weekly thereafter. For plastics containing plasticizer, replace the solution twice each week for the duration of the exposure. For other plastics, replace the fuel mixtures weekly. Continue sample exposure until constant weight is attained, or for a minimum of 500 hours. Observe safety precautions
40、 applicable to the handling of flammable and toxic mixtures (refer to OSHA and local laboratory procedures and standards). 4.1.3 Weighing the Samples During Conditioning Except for special situations, applicable to the second part as follows (conditioning in the worst-case fuel), weigh each sample a
41、t one week intervals to determine if absorption of the fuel has stabilized. Remove the samples to be weighed from the vessel containing the hot fuel and place them in a container of the same fuel at room temperature. Let the samples stand in the fuel for a period of 0.5 to 1 hour. Weigh a weighing b
42、ottle, in grams, to 4 decimal places. Remove one sample from the cool fuel, blot it, drop it into the weighing bottle and seal it within 10 seconds to prevent any further weight loss due to evaporation. Weigh the bottle containing the sample and record the weight of the sample (obtained by differenc
43、e from the tared bottle). Repeat this procedure for the other five samples (and for each fuel blend). If there is no change in Apparent Percent Weight Increase for each sample in a particular fuel (as defined in Appendix A) for three consecutive weighings, the five samples are to be removed for dryi
44、ng. The exposure of the sixth plastic sample in each set is to continue until the worst-case fuel has been determined, at which time exposure will be continued only for the sample in that fuel. (See Equation 1.) Apparent Percent Weight IncreaseWt of bottle sample+()wt of bottle Original wtOriginal w
45、eight- 100=(Eq. 1) Once it has been determined that equilibrium has been reached, the weights for each sample for the last three weighing periods will be averaged. This value will be termed the Equilibrium Swollen Weight for that sample. NOTE: The time necessary for the samples to reach equilibrium
46、may vary from one test fuel to another. Therefore, exposure to a test fuel should continue until the statistical treatment of successive Apparent Percent Weight Increase determinations indicate that equilibrium has been attained in that fuel. It might be expected that samples in the worst-case fuel
47、will reach equilibrium more rapidly than in any other. However, this assumes that there is only one mechanism involved in the absorption process, which might not be the case. SAE J1748 Revised SEP2007 - 5 - 4.1.4 Drying the Samples After recording the Equilibrium Swollen Weights, air dry the samples
48、 in a hood for 24 hours, and then dry them in a vacuum oven at 100 C to a constant weight. Weigh the samples every 48 hours to determine the “interim dry weight“ until there is no change in the Percent Weight Lost of any sample group for three consecutive weighing periods (using the statistical principles in Appendix A). (See Equation 2.) Percent Weight LostEquilibrium Swollen Weight “interim dry weight”()Equilibrium Swollen Weight- 100=(Eq. 2) Once
