Chemical resistance also tests

The effects of corrosion on other properties need similar direct assessment in many cases. However, in the absence of accepted standard tests the BS, DIN, ISO tests for laboratory glassware are often used. At the present time, the British Standard BS 3473 Methods of testing and classification of the chemical resistance of glass used in the production of laboratory glassware is being re-issued in six parts, of which the first five parts are identical to recently revised ISO test procedures. There are also corresponding DIN tests in some cases which are very similar. The current situation is ... 

Chlorinated polyether is formulated particularly for products requiring, good chemical resistance. Other materials exhibiting good chemical resistance include all of the fluorocarbon plastics, ethylpentenes, polyolefins, certain phenolics, and diallyl phtha-late compounds. Additives such as fillers, plasticizers, stabilizers, colorants, and type catalysts can decrease the chemical resistance of unfilled plastics. Certain chemicals in cosmetics will affect plastics, and tests are necessary in most cases with new formulations. Temperature condition is also very important to include in the evaluation. Careful tests must be made under actual use conditions in final selection studies. 

Portland cement is susceptible to corrosion by CO2 and H2S. The chemical attack by CO2 is called carbonation. A microsample technique has been developed to study the CO2 corrosion in cements, because the corrosion is difficult to monitor with common test procedures [264]. This technique is also advantageous as an accelerated testing method. A polymer-modified cement has been tested in field studies [694]. The addition of silica also improves chemical resistance [146], in particular brine corrosion. 

All these data support the idea that QA may function as chemical defense compounds. We also tested whether this chemical defense is relevant for the survival of a lupin plant. Lupins offer a unique chance to explore this question experimentally plant breeders have selected "sweet" varieties, which have a very low alkaloid content. These varieties can be compared to semi-bitter or bitter ones. We have grown Lupinus albus strains that differ in their alkaloid content in our experimental garden and greenhouse and have monitored their susceptibility to attack by plant pests. As can be seen from Figure 2, "sweet" lupins are preferentially eaten by rabbits (Cuniculus europaeus) or are infested by aphids (Aphidae) or leaf miners (Agromyzidae). Literature data also support the assumption that alkaloid-rich lupins are much more resistant to plant pests than "sweet" varieties (30-32). We conclude therefore, that QA are indeed important for the fitness of a lupin plant and that they constitute a major part of its chemical defense system, in which... 

When more than one plastic resin is used to fabricate bottles, it is necessary to demonstrate the equivalency of the container produced using the different resins. In addition, comparative data derived from light transmission, chemical resistance, extractables, and moisture permeation/vapor transmission tests described in the USP should be provided as applicable to the type of product. (For example, moisture permeation for an aqueous dosage form would not be necessary). Whereas the compendia discuss these tests only in the context of polyethylene, the guideline makes no distinction as to the resin used. It also should be verified that copies of letters authorizing FDA reference to appropriate DMFs from manufacturers of the resins used to fabricate bottles and from the bottle fabricator s), if available, are included. Although most resin suppliers include information on extractables data in their DMFs, it should be pointed out that fabricators may have to add release agents or other additives not covered by extractables data in the DMF of the resin supplier. 

When you purchase electronics, electrical circuits, components, wire, connectors, and devices, document the voltage and current, temperature and chemical resistance ratings and your needed requirements for these items. This will give you an easy reference as you proceed with testing. The supplier and the manufacturer of the part should also be noted as different brands of components may not match in quality. Some brands may fail where other brands may not. 

Construction applications for sulfur have also been tested. Interlocking bricks made predominantly of sulfur have been found to speed up construction, but have inherent fire hazards, which restrict their use. Concrete blocks impregnated with molten sulfur have shown a more than tenfold increase in compressive strength, from 5.9 to 83.9 MPa (megapascals 1 MPa = 10 N/m ), at the same time as an improvement in tensile strength from 1.3 MPa to 8.5 MPa, for a 13-15% sulfur content [7]. It also improves its chemical resistance. Sulfur-coated bamboo has been found to be an economical yet effective concrete reinforcing agent as a replacement for steel, in areas where bamboo occurs naturally. 

By spot-tests on coatings and immersion-tests on castings the excellent chemical-resistance of phenalkamine-cured epoxy systems has been demonstrated. In addition, near-infrared cure studies have documented the rapid complete cure of epoxies at room temperature and also satisfactory cure at reduced temperatures when phenalkamines are used as the curing agents. 

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. 

However, it is not just transparency and matting efficiency that are important for the appearance and the surface quality of furniture coatings, the chemical resistance must also not be disregarded. Household chemicals were tested in accordance with DIN 68861 Part 1 B. Here too, ACEMATT HK 460 produced some very good results in comparison to other non-coated matting agents (Table 4). For comparison reasons the surface treated ACEMATT OK 520 was included. 

Chemical test. Solubility is a very effective test to identify fibers. Polyolefins have excellent chemical resistance to most common solvents, and they can be easily distinguished from a polyester or nylon fiber by a simple solubility test. Functional groups can also be identified using a technique such as FTIR which wiU help identify the fiber type. 

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