Saturday, June 30th, 2012
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Adhesion of Dimer-Based Polyurethanes to Various Substrates
Dimerized fatty acids are expected to have a high affinity for low-energy surfaces, since the long alkane chains show a structure similar to polyethylene.Polyurethane adhesives were prepared from a variety of polyether and polyesters diols and pure MDI in an NCO:OH ratio of 2.5.These materials were tested as adhesives for two polyethylene substrates and for steel after full cure.It should be realized that these tests were performed to quantify the difference in adhesion of the PU resins to polyethylene forRead More …
Four different chemical methods can be used against plastics deterioration
Theoretically, there are four different chemical methods that can be used against plastics deterioration. The first technique is to introduce additives that absorb light before they can contact the degradation-initiating center and the energy is dissipated as heat. The second way consists in deactivating the excited state of the initiating center.Again, such reactions produce energy, which is generated either in the form of heat or as fluorescent radiation. In the third method, the hydroxyperoxides that have been formed are transformedRead More …
Some Important factors to polyester coating degradation
Polyester degradation is affected by solar radiation, photocatalytic admixtures, water and moisture, chemicals, oxygen, ozone, temperature, abrasion, internal and external stress, and pigment fading.Out of all these, the following factors, all present in outdoor weathering, are the most important to coating degradation: moisture, temperatures, oxidation ,UV radiation. Moisture Hydrolysis occurs when a plastic is exposed to water or humidity.This chemical reaction may be a major factor in the degradation of condensation polymers such as polyesters , where the ester groupRead More …
D5 Creation