1、 FORD LABORATORY TEST METHOD BO 027-01 Date Action Revisions 2001 03 27 Revised Editorial no technical change A. Cockman 1992 07 28 Printed copies are uncontrolled Page 1 of 5 Copyright 2001, Ford Global Technologies, Inc. RESISTANCE OF RIGID POLYMERS TO CRAZING Application This procedure describes
2、a method for determining the craze characteristics of rigid polymeric materials under stress. The method is applicable to molded test specimens or samples cut from fabricated parts. Equipment Required Test Rack See Figures 1 and 2. Weights See Figure 3. Weights are designed to stress test bars to lo
3、ads of 1000 and 2000 psi. Burette One 500 mL per test bar. Test Stand and Burette Clamp To position burette over fulcrum point of test bar. Catch Basin Pan of suitable size to hold solution as it drips from test bars. Light Source “Dazor“ desk lamp or flashlight to place behind rack to observe craze
4、 marks on test bar. Tape 1/2 inch pressure sensitive. Crazing Agents ESF-M5B2-A; ESF-M5B217-A; Aromatic hydrocarbons; halogenated hydrocarbons; ketones; organic or inorganic acids; aliphatic hydrocarbons. Conditioning and Test Conditions All test values indicated herein are based on material conditi
5、oned in a controlled atmosphere of 23 +/- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. FORD LABORATORY TEST METHOD BO 027-01 Page 2 of 5 Copyright 2001, Ford Global Technologies, Inc. Procedure 1. Prepar
6、e four specimens 1/2 inch wide by 5 inches long by 1/8 inch thick for each load. These can be made either by the injection molding of bars or by sawing cast or extruded sheets. Specimens must be free of cracks, dirt, voids or feathered edges. Remove saw marks along the edges of the specimens by sand
7、ing and buffing. 2. Suspend the required static load 1/8 inch from the end of the bar to provide a fiber stress of 1000 and 2000 psi. This must be done before the crazing agent is applied. Fasten the weight to the test bar, utilizing a small piece of tape over the wire weight holder. 3. Mount one en
8、d of the specimen in the test rack of Figure 1 as shown in the detailed sketch of Section A-A. The fulcrum must be exactly 2 3/4 inches from the stationary end. 4. Check the samples immediately upon application of the load, check again after a few minutes and then allow to stand for two hours. For t
9、he remainder of the test use the maximum load that does not produce crazing in the untreated specimens. If crazing occurs at 1000 psi, a smaller load should be used to calculate either a new weight or new fulcrum distance for this load utilizing the equation. Calculation of Fiber Stress S = Fiber St
10、ress (psi) W = Applied Load (lbs.) L = Distance of load from fulcrum (inches) B = Width of specimen (inches) T = Thickness S = 6WL Bt 2 The load required to obtain a given stress is: W = SBt2 6L 5. Repeat Steps 1 to 3, positioning the burette so that the crazing agent will be applied to the fulcrum
11、area. Do this prior to Step 3. Place the catch basin beneath the test bars. 6. Adjust the burette stopcock to apply the crazing agent at a rate of 10 20 drops per minute. 7. Check samples immediately upon application of the crazing agent, again after a few seconds, and at five minute intervals up to
12、 30 minutes. If crazing does not occur within this time, inspect the specimens every 30 minutes for two hours. If crazing does not occur within this time, the test should be discontinued. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each p
13、arty is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD BO 027-01 Page 3 of 5 Copyright 2001, Ford Global Technologies, Inc. RESISTANCE OF RIGID POLYMERS TO CRAZING Craze Resistance Test Rack Figure 1 FORD LABORATORY TEST METHOD BO 027-01 Page 4 of
14、5 Copyright 2001, Ford Global Technologies, Inc. RESISTANCE OF RIGID POLYMERS TO CRAZING Craze Resistance Test Rack - Details - Figure 2 FORD LABORATORY TEST METHOD BO 027-01 Page 5 of 5 Copyright 2001, Ford Global Technologies, Inc. RESISTANCE OF RIGID POLYMERS TO CRAZING Weights for Craze Test Figure 3
