Synthesis and characterization of sustainable polyurethane modified by cyclic polysiloxane

Abstract

In this article, a series of sustainable polyurethanes are prepared by introducing different content of cyclic polysilanol, which may act as a chain extender to replace 1, 4-butanediol (BDO). Consequently, cyclic polysiloxanes are successfully incorporated into the molecular chains to afford organic-inorganic polyurethanes and then their effects on polyurethanes thermal properties and surface hydrophilicity are fully characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact angle testing. Results show that the hybrid polyurethanes display enhanced glass transition temperatures (T g ). While in terms of TGA, the effects of cyclic polysilanol on thermal properties seem complex, which would reduce the thermal stability in the first degradation process but enhance in the second process. The morphology observed by scanning electron microscopy (SEM) show that the inorganic constitutions, namely, cyclic polysilanol, may occur to self-condensation or aggregation, which can help to explain the uncommon thermal phenomenon above. Thus, an opportunity of future applicability in the areas of sustainable polymer with improved properties can be envisioned in our research method of hybrid polyurethanes.

Crosslinker free thermally induced crosslinking of hydrogenated nitrile butadiene rubber

“…The crosslinking density obtained by either !-rays or thermal radiation 25 leads to lower density values of crosslinking that we obtained with a thermal treatment of 1 h 30 min at 240 8C (T3). Increasing treatment time to 3 h (T5) yielded to a crosslinking density of HNBR comparable with the one obtained with the curing aid mixture peroxide/sulfur (10/0.75) found by Sheng et al 44 As mentioned above, a further increase in time (24 h) at 240 8C caused a deterioration of the polymer film, which were not usable for determination of the crosslinking density. While can be controlled by the duration and the temperature of the thermal treatment, the involvement of nitriles and alkenes functional groups on this reaction should be defined.…”

“…The most commonly reported technique relied on the use of peroxide, which leads to highly crosslinked HNBRs as obtained by Likozar and Major 28 with a crosslinking density in the order of magnitude 10 3 . However, the efficiency of this technique varies as it can be seen with the results of Karger-Kocsis et al 43 and Sheng et al 44 who obtained a crosslinking density of 10 2 , whereas the one from Mamedov et al 25 was an order of magnitude lower. The use of peroxide is often preferred over sulfur because the latter gives lower crosslinking density when the butadiene content is low.…”

“…The use of peroxide is often preferred over sulfur because the latter gives lower crosslinking density when the butadiene content is low. 44 It can be noted that the composition of the composites, as well as the quantity of peroxide were different which can also have an impact on the percentage of HNBR crosslinking. Another approach studied is the use of radiation which also needs several additives to achieve an efficient crosslinking.…”

Influence of Polymethylsilsesquioxane Content to the Thermal Stability of Meta-Aramid Fiber Insulation Paper

“…From the overall trend, the MSD value showed the following trends: 2.5 wt % < 5.0 wt % < 0 wt % < 9.4 wt % < 7.2 wt %. Because the content was low, the MPIA chain occupied a large space that reduced the mobility of PMSQ [46]. Meanwhile, PMSQ molecules exhibited nanocrystalline phenomena and formed typical clusters due to their own interactions, weakening their own mobility [47]; then, the mobility of PMSQ decreases.…”

Surface Control of Thermosetting Fluorinated Polyurethane

“…Polyurethanes are used in a wide range of applications, mainly because their properties may be easily tailored to vastly different end results, ranging from stiff, thermoset materials to soft expanded elastomers [1] . It has been well-known that fluorine has the strongest electro negativity of all the elements ever known, and its atomic radius is merely larger than that of hydrogen [2][3][4] .…”