Tests hydrolytic stability

Accelerated hydrolytic stability tests Indicate that the polyether-based urethane employed In this study In the preparation of the liner pads can successfully withstand contlntious Immersion In water at 3S C for 24 years. Under such an exposure, the pads are expected to lose approximately 20 percent of their original compressive strength. 

The hydrolytic stability test was designed to determine the storage stability of organophosphorus processing stabilizers at two temperature/humidity conditions ... 

Figure 1. Circuit pattern for hydrolytic stability testing. Circuit Tin/lead over copper. Conductor width 0.7 mm. Space between conductors 1.2 mm.

Although most of the materials subjected to the hydrolytic stability tests displayed some propensity towards degrading under the severe test Conditions, we feel that the service life of all of the treated materials will not be limited by hydrolytic degradation processes. However, in some cases, the combination of hydrolysis and thermal-oxidative degradation processes could diminish the life of the sealant to an extent beyond that predicted by studying each factor separately. 

Hydrolytic Stability Test The stability of PSEG against hydrolysis in aqueous media was estimated as follows A polymer sample was dissolved in phosphate buffer (1.5 wt.% pH = 7.0 I = 0.05) at 4 °C. Every few hours, an aliquot of the solution was subjected to measurement of its turbidity after the sample was heated above the... 

Under heated or hydrothermal conditions, the possible degradation mechanism for AEMs has been discussed in the literatures. Hydrolytic stability of the AEMs is performed by treating the membrane in hot water for a specific period. Only a few reports are concerned with the hydrolytic stability so far. For Watanabe research gronps, they performed the hydrolytic stability test in hot water at 80 C for 500 h the chemical structures before and after the hydrothermal test were analyzed by the use of H NMR spectra. A long-term hydrothermal test was also performed for 5000 h, and the ionic conductivity was used to assess the stability. According to their results, the major degradation mode of the AEM (based on quaternary PES) under the hydrothermal condition is most likely to be the elimination of a tertiary amine to form benzyl alcohol and its further decomposition via dehydration. ... 

Biodegradable poly(phosphoester-urethanes) containing bisglycophosphite as the chain extender were synthesized. Methylene bis-4-phenyl isocyanate (MDI) and toluene diisocyanate (TDI) were initially used as diisocyanates. Since there was a concern that the degradation products could be toxic, the ethyl 2,6-diisocyanatohexanoate (LDI) was synthesized and replaced the MDI (or TDI). The hydrolytic stability and solubility of these polymers were tested. Preliminary release studies of 5-fluorouracil from MDI based poly(phosphoester-urethane) and methotrexate from LDI based poly(phosphoester-urethane) are also reported. 

Standard test for hydrolytic stability. The hydrolytic stability of the chlorinated resins was determined by the following test procedure. An acid digestion autoclave having a volume of 125 ml is charged with 40 ml of resin and 28 ml of deionized water. The bomb is sealed and transferred into an oven, pre-heated to 200 °C. The test is continued for 24 hours. The bomb is removed and cooled to ambient temperature. The liquid is separated from the resin and the chlorine content analyzed while the resin is washed thoroughly and its acid capacity is determined as described in section 5. The test results are shown in Table 2. 

Alcohol ethoxysulfates have been used in field tests as foaming agents for nitrogen (394) and carbon dioxide (395). Application of alcohol ethoxysulfates is restricted due to its limited hydrolytic stability at low pH and elevated temperature (396). 

In many commercial brochures, chemical resistance is indicated as excellent, good, fair, or poor. Although the test method is usually outlined, wide interpretation is possible. Immersion tests are usually described in this manner. Hydrolytic stability is tested by salt-spray cycling or autoclave cycling. 

Complementary laboratory experimental investigations of nPr-BTP hydrolytic stability revealed that /9,m values decreased by 80% after two days of contact of the nPr-BTP solvent with a 1 M nitric acid solution, but by 50% after only two hours, due to the artificial addition of nitrous acid (potentially formed by the alpha radiolysis of nitric acid during a hot test) at 0.02 M to the 1 M nitric acid solution (206, 207). 

Hydrolytic stability. The test method required treating the fluids with 0.1% water and maintaining the fluid at 77°C for up to 200 h. Samples were withdrawn at 20-h intervals, and the flash points were measured by the closed cup method. A decrease in flash point was interpreted as being indicative of hydrolytic breakdown to form low molecular weight products. The PAO showed no decrease in flash point under any of the test conditions. 

Although the perfume oil is usually the first suspect whenever odor or color changes occur in a finished product, it is not always the culprit. Odor and color changes in the product base itself may occur due to oxidation, hydrolytic breakdown, complex formation, bacterial decomposition, or other causes. Sometimes the causes for instability are hard to track down, as in a case in the experience of one of the authors, where an off-odor in a cream was due to microbial breakdown that was made possible by absorption and inactivation of the preservative by the plastic container. It is always advisable to conduct a stability test of the unperfumed product along with the test of the perfumed product. 

Figure 15.13 illustrates the hydrolytic stability of various polymeric materials, determined by a hardness measurement after exposure to high-RH aging. A period of 30 days in the 100°C, 95 percent RH test environment corresponds approximately to a period from 2 to 4 years in a hot, humid climate such as that of southeast Asia. The hydrolytic stability of urethane potting compounds was not believed to be a problem until it resulted in the failure of many potted electronic devices that were noticed first during the military action in Vietnam in the 1960s. 

FIGURE 15.13 Hydrolytic stability of potting compounds. Materials showing rapid loss of hardness in this test soften similarly after 2 to 4 years in high-temperature, high-humidity climate zones.35... 

The temperature/humidity conditions used may be more severe than the typical accelerated stability testing conditions in order to generate potential degradation products in a reasonable time. The typical forced degradation conditions include thermolytic, hydrolytic, oxidative, photolytic (in excess of ICH conditions), high pH (alkaline conditions), and low pH (acidic conditions). Outlined in Table 9-25 and Table 9-26 are some solid-state and solution forced degradation studies, respectively, that could be conducted. In the following... 

Figure 18.21 Comparison of hydrolytic stability. Pressure cooker test under 120 CC steam atmosphere. SPS (30% GF), PBT (30% GF), PA66 (30% GF), PPS (40% GF)...

ASTM D 3137-81 (1987) Standard Test Method for Rubber Property — Hydrolytic Stability, 3 pp (DOD Adopted) (FSC 9320) (MR) (Comm D-11)... 

To test its hydrolytic stability this silane surfactant was stored as aqueous solutions (O.lwt.%) over a range of pH values from 2 to 12. The diameters obtained from spreading of a 50 pL droplet was unchanged over a period of more than six months. This is convincing proof that no significant decomposition takes place. This extraordinary stability under both acidic and alkaline conditions allows the use of such silane surfactants in applications where long term storage is required. 

Many Investigators of hydrolytic stability of polymers utilize hardness measurements since the readings are very easy to take and the tests are essentially nondestructive, thus obviating the need for many test specimens. This work emphasizes that high retention of hardness does not prove that the material has displayed a good retention of other physical properties or withstood extensive degradation. 

Although hydrolytic stability of the higher alkyl 2-cyanoacry-late-cemented specimens increased with the length of the ester chain, all bond strengths were observed to decrease as a function of the time specimens were stored in water. Results of these tests with specimens stored up to 6 months are given in Table I and Fig. 

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