FORD FLTM BP 101-1-2001 RUBBER - DEGRADATION BY OZONE (Replaces FLTM BP 001-01 FLTM EU-BP 001-01).pdf

1、FORD LABORATORY TEST METHOD BP 101-01 Date 2001 08 23 1991 1003 RUBBER - DEGRADATION BY OZONE Action Revisions Revised Editorial - no technical change A. Cockman Application This method is used to assess the resistance of rubber materials to accelerated ozone attack under static and dynamic conditio

2、ns Scope This method gives procedures for estimating the comparative ability of soft elastomeric materials to withstand the effects of cracking in a controlled ozone environment when held under constant strain or when subjected to dynamic strain. Tests can be performed on flat sheet (slab stock), st

3、andard specimens prepared from parts, or actual parts. Apparatus Required Ozone Test Cabinet The cabinet interior shall be constructed of a material that will not be affected by ozone and shall be designated to allow suspending mounted test specimens without shielding or masking any specimen from th

4、e ozone/air flow. The ozone-air mixture must be introduced into the chamber and circulated in a manner that provides uniformity of temperature and ozone concentration throughout the chamber. The ozone concentration and chamber temperature shall be continuously controlled and recorded. NOTE: It is re

5、commended that the ozone generator be of the ultraviolet lamp type to avoid the possibility of forming oxides of nitrogen. Avoid observing the lamp when in operation as serious eye injury may result. As ozone in concentrations higher than ambient may be hazardous to health, avoid breathing concentra

6、ted ozone when introducing or inspecting samples in the chamber. Equipment that discharges ozone at quantities greater than 0.05 ppm into the laboratory should be exhausted to the outside atmosphere. Equipment is available that automatically controls the ozone concentration, temperature, and provide

7、s an autographic record of these conditions. As additional assurance of uniform ozone exposure over and above that which is provided by air handling provisions of the chamber, a moving specimen carrier for circulating the specimens along a predetermined path in a plane normal to the gas flow is perm

8、issible. Intake air should be filtered to remove particles. Dynamic flex apparatus in conformance to ASTM D 3395 with adjustable shaft movement of 12 - 50 mm incorporated in the chamber design are recommended. Copynght02001, Ford Global Technologies, Inc COPYRIGHT Ford Motor CompanyLicensed by Infor

9、mation Handling ServicesFORD LABORATORY TEST METHOD BP 101-01 Unless defined in the applicable Engineering Materials Specification, Engineering Specification, or Engineering print, the following standard conditions are to be met: Ozone concentration: 50 + 5 pphm (50 mPa partial pressure) Temperature

10、: 38 + 1 OC Duration of exposure: 70 + 2 h Air-Ozone replacement rate (throughput): 1.2 - 2.0 changedmin Air-Ozone velocity over specimens: 60 + 5 cm/s Calibration method and frequency will be defined by Ford Motor Company (to be established) Sources for equipment capable of meeting the requirements

11、 of this method are as follows: Hampden Test Equipment Ltd. Mast Development Co. Unit 5, Bunting Road Industrial Estate 2212 E. Twelfth St. Kingsthorpe Davenport, Iowa 52803 Northampton NN2 6EB U SA United Kingdom Nordman Rossman e.g., brake hoses, rubber coated cloth, and diaphragm materials.) Fixt

12、ures (various) For mounting specimens to mobile test piece carrier in the chamber, mandrel mounting, clamps and brackets for dynamic ozone testing, and actual component assemblies for installations of elastomeric parts according to simulated in service conditions. Specimen Holder Available from Atla

13、s Electric Devices Co. Refer to Figure 1 Flexible Rule Typical plastic “pocket scale“ graduated in 1 mm divisions for measuring distance increase between bench marks on both straight and mandrel-mounted specimens. Materials Required Marketing Devices For applying “bench marks“ to establish elongatio

14、n of specimens. Marking techniques may include use of aluminum powder with wedge applicators, and light-colored opaque inks and vinyl “flags“ for dark materials or various dark ink pens for light materials. Fasten i ng Wire For securing mandrel-mounted specimens. It may be soft stainless steel, alum

15、inum, or enameled copper wire of a diameter that permits controlled installation of test specimens onto the mandrel. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 OC and 50 +/- 5 % relative humidity for not

16、less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Page 3 of 10 Copynght02001, Ford Global Technologies, Inc COPYRIGHT Ford Motor CompanyLicensed by Information Handling ServicesFORD LABORATORY TEST METHOD BP 101-01 Procedure A. Conditioning Minimal hand

17、ling of the specimens during and after installation into test fixturing is recommended in order to not disturb protective anti-ozonants that migrate to the polymer surface. Coat non-test areas with protective coating as appropriate. Unless otherwise specified, the prestressed materials are to be con

18、ditioned according to ASTM D 1349 at 23 + 2 OC and 50 + 5 % relative humidity for 24 h minimum in a draft free, ozone-free, darkened atmosphere. (Note: Omit conditioning for dynamic testing .) B. Procedure A (Static-Straight) Prepare test specimens from slab materials and actual parts into either un

19、iform width and thickness or tensile-shaped (D 412 and IS0 37) specimens. For straight specimens, cut into lengthwise strips by sharp die or surgical blade and metal guide to a uniform width of 2.0 - 12.0 mm and a length of not less than 35 mm. Unless otherwise specified, strain to an elongation of

20、20 +/- 1 %, established by the measurement of “bench marks“ placed upon the specimen and measured according to ASTM D 412 and IS0 37. Elongate specimens as described in ASTM D 518 using wood mounting blocks, clamps, frames, or other suitable means of achieving accurate elongations (see Figure 1). Re

21、port die type or sample dimensions and observe for cracking with 2X magnification prior to specimen relaxation. Note 1: Testing of straight specimens imparts greater stress at the clamping region than that of tensile-shaped specimens making the use of protective coatings in the clamp region advisabl

22、e. Note 2: When evaluating slab material, the manufacturer is to certify it to be of the same material and equivalent cure as the finished part. C. Procedure B (Static-Mandrel) Continuous extrusions (or molded, if of sufficient length) of hose, tube, and weatherseal and composite constructions that

23、would otherwise be difficult or impractical to elongate by Procedure A may be evaluated by wrapping about a mandrel. Select a mandrel of suitable diameter to elongate the surface 20 % unless otherwise specified. Determine elongation by observing the increased distance between initial “bench marks“ (

24、IO mm minimum, 50 mm maximum) applied to a relaxed sample to the nearest 1 mm and secure the assembly by wire (see Figure 2). Note 1 : Because accurate measurement of the increase in distance between benchmarks when on the mandrel becomes increasingly difficult as thickness becomes less, the use of

25、Procedure A is encouraged when evaluating unreinforced slab or sheet materials that are easily elongated. Page 4 of 10 Copynght02001, Ford Global Technologies, Inc COPYRIGHT Ford Motor CompanyLicensed by Information Handling ServicesFORD LABORATORY TEST METHOD BP 101-01 Note 2: For non-extensible th

26、in coated fabrics (diaphragm, etc.) where determination of surface of elongation is not practical, use mandrel-mounted techniques described in ASTM D 3041 . “Bull dog“ style clamps in place of varnished wood mounting strips are permitted. Evaluate cracking on those materials with 7X magnification. N

27、ote 3: Molded rings and seals may be circumferentially elongated by carefully sliding onto a polished metal mandrel using the procedures described in FLTM BP 116-01. Select a mandrel diameter to achieve 20 % elongation unless otherwise specified. (Note: Seals with rigid housings may require removal

28、of the elastomer from the housing unless the seal is to be evaluated at engineered stress. In the latter case, refer to FLTM BP 116-01 and Procedure C below.) D. Procedure C (Static-Simulated Installation) This procedure is to evaluate the effects of ozone on finished parts in their assembly conditi

29、on while under inherent design strain (undetermined), on extruded or molding lengthwise parts wbject to strain from bending or curving about a radius, and on components under compression. Examples are bushings in compression or in torsion (or a combination of both), seals, and O-rings compressed, or

30、 circumferentially elongated while installed in their assemblies, and cut tubing and hose installed on actual production fittings with production clamps. Tests on specified parts are to be described in the applicable Engineering Specifications and Drawings. Note: The utility of these tests for parti

31、cular components should be established by consultation with Central Laboratory prior to incorporating into specifications. An accurate description of the type of applied stress and/or required fixturing is necessary for valid and reproducible tests. Observe for cracking by using 2X magnification on

32、exposed external surfaces of the component prior to removal from any fixturing. Report percent strain (if determinable) in compression or tension and rate cracking according to Table I. Describe location of cracking. Note: Photographs at 2X magnification are particularly useful when reporting and de

33、scribing ozone effects on actual components. E. Procedure D (Dynamic Flex-Severe ServiceBent Loop) This procedure is for evaluating non-extensible (reinforced) nibber materials and components for ozone resistance during continuous flexing. Although this procedure provides a specific example for brak

34、e hose for illustrative purposes, other composite materiaIs/components such as engine belts may be evaluated as described in their applicable Engineering Specification or Drawing. Note: It is recommended that Central Laboratory be consulted before incorporating these tests into specifications. Refer

35、 to ASTM D 3395 for dynamic ozone evaluation of extensible materials (unreinforced). Page 5 of 10 Copynght02001, Ford Global Technologies, Inc COPYRIGHT Ford Motor CompanyLicensed by Information Handling ServicesFORD LABORATORY TEST METHOD BP 101-01 Under the reciprocating shaft of the dynamic ozone

36、 flex apparatus and attached mounting fixtures at the minimum opening position, install a length of material to achieve desired maximum surface elongation when forming a loop. Determine elongation of the bent-loop by observing the distance increase between “bench marks“ when the material is flexed f

37、rom its relaxed position (see Procedure B). For typical brake hoses, a 200 mm length forming a loop when installed at a 35 mm minimum opening gives 25 - 30 % surface elongation (see Figure 3 for appropriate fixturing). With the reciprocating shaft positioned at its maximum opening, observe and recor

38、d the minimum surface elongation of the loop. For brake hoses, this elongation should be approximately 10 - 15 %. Observe and record both maximum and minimum elongations. Note: Material thickness will govern the ability to achieve a desired elongation when forming a loop using standard flex equipmen

39、t presently available from ozone chamber manufacturers. Adjustment of stroke length, material length and/or fabrication of fixturing to achieve the desired maximum elongation will be required. Minimum elongation will vary accordingly. Caution: The length of material between fixturing should be suffi

40、cient to prevent the specimen from being subjected to tensile forces when the fixture cycles to the maximum open position. Verify adequate length by manually cycling the flex apparatus before starting the test to avoid damage to cycling apparatus and fixtures. Unless otherwise specified, all tests a

41、re to be conducted at 0.5 + 0.05 Hz for 500 continuous hours (approximately 1 O00 O00 cycles) at standard concentration and temperature. At the end of this period, examine the surface of the material in the area forming the loop and areas adjacent to attachment with 7X magnification. Report maximum

42、and minimum elongation and rate according to Table I. F. Reporting Report method used and sample mounting description. If simulating actual in-service installations, include a drawing or photograph of fixturing and mounting. Observe cracking in the stressed areas prior to relaxation and report class

43、ification rating. As an alternative, report the percent retention derived from the three-digit rating method from 24 h interval observations as described in ASTM D 11 71. Report percent strain, duration, temperature, and ozone concentration if other than standard conditions. Page 6 of 10 Copynght020

44、01, Ford Global Technologies, Inc COPYRIGHT Ford Motor CompanyLicensed by Information Handling ServicesFORD LABORATORY TEST METHOD BP 101-01 RUBBER - DEGRADATION BY OZONE Table I - Evaluation (all procedures) Classification of Rating O 1 2 3 Interpretation No checking or cracking visible at 2X mag n

45、ification Checking or cracking visible at 2X but not visible to the unaided eye Small checks or cracks visible to the unaided eye Medium or large cracks visible to the unaided eye Table II - Optional Evaluation (Quality Retention Rating Based on Three Successive Observations at 24, 48, and 70 Hour I

46、ntervals - Reproduced from ASTM D 11 71) Observed Crack Rating at Three Successive Intervals O00 O01 o1 1 111 002 o1 2 112 022 122 222 003 O1 3 113 023 123 223 033 133 233 333 Resistance to Ozone (%) 1 O0 95 90 85 80 75 70 65 60 55 45 40 35 30 25 20 15 10 5 O Page 7 of 10 Copynght02001, Ford Global

47、Technologies, Inc COPYRIGHT Ford Motor CompanyLicensed by Information Handling ServicesFORD LABORATORY TEST METHOD BP 101-01 Reference Documents ASTM D 1349, Practice for Rubber, Standard Temperatures and Atmospheres for Testing and Conditioning ASTM D 412, Rubber Properties in Tension (Die-C Tensil

48、e Specimens) ASTM D 395, Rubber Properties in Compression ASTM D 11 71, Surface Ozone Cracking - Quality Retention Rating ASTM D 3041, Ozone Cracking Coated Fabrics ASTM D 3183, Preparation of Pieces for Test Purposes from Products ASTM D 3395, Rubber Deterioration - Dynamic Ozone Cracking in a Cham

49、ber FLTM BP 11 6-01, Rubber - Permanent Tensile Set Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. Page 8 of 10 Copynght02001, Ford Global Technologies, Inc

50、 COPYRIGHT Ford Motor CompanyLicensed by Information Handling ServicesFORD LABORATORY TEST METHOD BP 101-01 RUBBER - DEGRADATION BY OZONE Figure 1 (Procedure A) (ASTM D 412 Specimen In Elongation) Figure 2 (Procedure B) (Mandrel - Mounted Specimen Rubber Specimen (Approximently 20% Elongation) Page