Chemical resistance tests

When carrying out chemical resistance tests, it is advisable where possible to use the same solution that the product is going to be used in. This will help cover the interpretation of the effects of several different chemicals that may be in a commercial mixture. 

Chemical resistance tests are not uniform, in concentrations, temperature, time, or properties measured. 

Chemical resistance test for rubber linings by Atlas blind flange test Determination of effects of liquid chemicals on plastics Determination of environmental stress cracking (ESC) by the bent strip method... 

The second chemical resistance test, the water attack test, is exclusively used for Type II glass because its properties come from a coating that would not be represented if powdered. In this test, containers... 

Results of some of these short-term tests are shown in Table II. A comparison is given between PPS and five other plastics nylon (Zytel 101), polycarbonate (Lexan 141), polysulfone (Bakelite Polysulfone), polyphenylene oxide (Noryl), and polyetherimide (Ultem 2300). The data presented are based upon retention of tensile strength for all plastics except the Ultem 2300, which is based upon retention of flexural strength. Unsuccessful attempts were made to injection mold ASTM Type IV tensile bars out of the Ultem compound, but flexural strength bars could be made. Experience has shown that chemical resistance tests monitored by flexural strength retention are comparable to those monitored by retention of tensile strength. 

Even before the discovery of vulcanisation by Goodyear [1], the effects on rubber of heat, light, acids and alkalies were studied. Testing became necessary when early investigators faced problems with rubber and its vulcanisates. Possibly the earliest chemical resistance test on rubber was undertaken by Goodyear when he treated rubber with nitric acid and this yielded a hardened mass [2, 3]. He mistakenly called this phenomenon vulcanisation, before he accidentally discovered vulcanisation with sulfur at a later point. 

Stress rupture tests on test pieces are very important under conditions where, in addition to the stress, the atmosphere is chosen to accelerate failure. The best known t> pe of test is a test of the so-called environmental. stress cracking of plastics, where the aggressis e atmosphere is a chemical that causes cracking when the material is in a strained state. These tests are usually considered as a form of chemical resistance test and are cosered in Chapter 14. Ozone cracking of rubber, also an environmental resi.stance test, is another example. 

The effect of a liquid on a polymer may be swelling, chemical reactions, or extraction of constituents of the material—or indeed all three. Exposure of polymers to chemicals is generally termed a chemical resistance test, although for rubbers they are more frequently referred to as swelling tests, volume swell tests, or oil aging (because standard grades of oil are frequently specified as the liquid). 

The results of chemical resistance tests with test-motor-fuel(DIN 53521 Fuel No. 2) are shown in Figure 4. 

Chemical resistance tests with sulfuric acid(s.g.=1.28) showed the same behavior as those with test-motor-fuel(Figure 5). 

Various tests and analytical methods are used for the characterisation and evaluation of the properties of vegetable oil-based polymer composites. Mechanical tests for properties such as tensile, flexural, compressive, impact, hardness and wear are carried out by a universal testing machine (UTM), and by equipment for testing impact, hardness, abrasion loss, and so on. Weather and chemical resistance tests are performed in UV/ozone, an artificial environmental chamber and in different chemical media. Water uptake and biodegradability tests are carried out by standard ASTM methods. Biodegradability and biocompatibility may be studied by the same procedure as described in Chapter 2. However, in practice only a few such studies have been performed for vegetable oil-based composites. 

Resins and hardeners being used and their shelf life so far Chemical resistance test should be done for resins and hardness A test piece should be made by the vendor and subjected to actual operating conditions for determining the suitability Curing method which will be used by the contractor... 

Laboratory Glassware. Chemical resistance tests are specified in B.S. 3473. There are other standards for particular... 

Table A.17 provides the results of stress cracking resistance and chemical resistance tests. The stress cracking resistance of PMMA against a variety of media was evaluated using a test procedure similar to MIL 8184 (Section 2.5.5.2.1.3 [269]).

The chemical resistance tests were conducted similar to DIN 53476. Assessment criteria were changes in appearance, weight, and stability after exposure to the media. The time (in days) until the first changes in the specimen were visible was recorded and is listed in column ET. An additional short time test (1 minute duration) identifies particularly aggressive media. The table also provides an overall rating based on the tests results for stress cracking resistance and chemical resistance. 

Table A. 1 7 Results of stress crack resistance and chemical resistance tests...

Chemical resistance test made in the spedlic medium with which the coating is in contact (22 and 94 h at 23°C and 60 days at 60°Q. 

Chemical resistance tests are conducted using four different methods ... 

In Figure 17.9, pictures of the screwed boss after the chemical resistance test are shown. Salad oil as a chemical was applied onto the surface of the screwed boss, and the screwed boss was kept at room temperature for 2 days, then the observation of cracks in the boss was carried out. The chemical resistance of HIPS/SPS blends and HIPS against various chemicals used in daily life is listed in Table 17.2. 

Figure 17.9 Pictures of the chemical resistance test with the screwed boss. Salad oil was apphed on the boss surface for 48h at room temperature, (a) HIPS/SPS (80/20), (b) HIPS, (c) ABS, and (d) screw used for this test.

An important point about chemical resistance testing is the non-uniformity of the available data. There are a few standard test methods but many people conduct their own tests and do not follow the standard methods. Only a few of the currently applied chemical resistance tests have been standardized. One reason for the absence of widespread acceptance and use of standardized chemical resistance test methods is the magnitude of the number of applications and conditions which are impractical to capture in standardized tests. 

Performing mechanical tests (tensile, impact) after the chemical resistance tests. 

An important point about chemical resistance testing of rubbers and elastomers is the non-uniformity of the available data. 

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