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171.
172.
M. Thirumal Dipak Khastgir Nikhil K Singha B. S. Manjunath Y. P. Naik 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):704-712
Water blown rigid polyurethane foams (PUF) with organoclay/organically modified nanoclay (ONC) were prepared and their properties such as density, mechanical, morphological, insulation, thermal and flame retardant properties were studied. In this investigation, the ONC content was varied from 1 to 10 parts per hundred of polyol (php) by weight. It was observed that the compressive strength of ONC filled PUF increased up to 3 php of ONC loading and then it decreased. Wide angle X-ray diffraction and transmission electron microscopy studies indicated the exfoliated dispersion of ONC in PUF. The thermal conductivity of ONC filled PUF decreases up to 5 php and then increases. The glass transition temperature (Tg) of PUF decreases on loading of ONC. The TGA analysis shows that there is slight increase in degradation temperature with increase in ONC loading. The flame retardant properties (LOI and flame spread rate) are improved slightly on addition (3 php) of ONC filled PUF. 相似文献
173.
Abstract Photograft copolymerization of methyl methacrylate on reduced wool (reduction done by treatment with thioglycollic acid, TGA) was studied at nearly 30°C using a Ce4+ -oxalic acid redox initiator system in a limited aqueous system (2.7 mL water for 0.15 g wool). Reduction of wool for 16 h with 15% TGA solution produced optimum grafting effects. Percent grafting and grafting efficiency under different sets of conditions were studied and compared, and the mechanism of grafting discussed. Generation of grafting sites (radical centers) on reduced wool was more effective in the presence of light than in the dark. Percent grafting of 250–350% and grafting efficiency of 65-80% over a conversion range of 60–90% in 3–5 h were easily obtained. 相似文献
174.
Several new random and block copoly(imide siloxane)s have been prepared by the solution polycondensation of commercially available 4,4′-oxydianiline (ODA) and amino-propyl terminated polydimethylsiloxane (APPS) with 4,4′-(hexafluoro-isopropylidene)diphthalic anhydride (6FDA). The siloxane loading was kept to 10, 20, 30, 40 and 50 wt% in the copolymers. The random copolymers were prepared by a one pot solution imidization technique, and two pot solution imidization technique was adopted for the synthesis of the block copolymers. The diamine ODA and the dianhydride 6FDA composed the hard block segment, while APPS and 6FDA composed the soft block segment. The hard block length was kept constant while the soft block lengths were varied by varying the siloxane loading. Accordingly, block copoly(imide siloxane)s were prepared on increasing the soft block lengths (DP) from 3 to 6, 10, 18 and 36 for fixed hard block length of 22. The resulting polymers have been well characterized by IR, NMR and GPC techniques. Thermal and mechanical properties of the random and block copolymers were compared with the already reported homopolyimide without siloxane moiety. 相似文献
175.
Anindita Ghosh 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):578-584
Four new poly(etherimide)s have been synthesized by reaction with commercially available bisphenol‐A‐(diphthaleic anhydride) (BPADA) with four different kinds of diamines, namely 4,4′‐bis(p‐aminophenoxy‐3,3″‐trifluoromethyl) terphenyl,4,4′‐bis(3″‐trifluoromethyl‐p‐aminobiphenyl ether)biphenyl,2,6‐bis(3′‐trifluoromethyl‐p‐aminobiphenyl ether)pyridine, 2,5‐bis(3′‐trifluoromethyl‐p‐aminobiphenylether)thiopene. The poly(etherimide)s are named as 1a, 1b, 1c and 1d, respectively. The synthesized polyimides show good solubility in various organic solvents. The polyimide films had low water absorption of 0.19–0.30% and low dielectric constant of 2.79–3.1 at 1 MHz. These polyimides showed very high thermal stability with decomposition temperature (5% wt loss) up to 522°C in nitrogen. Transparent thin films of these polyimides exhibited tensile strength up to 97 MPa, a modulus of elasticity up to 1.56 GPa and elongation at break up to 20%. 相似文献
176.
Facile synthesis of novel ibuprofen bearing polyurethane 1 has been achieved for the first time and found to display the release pattern of ibuprofen based on the easy cleavage of ester linkages. Thorough characterizations (FT‐IR, UV‐Vis, NMR, and elemental analysis) were performed to ascertain the structure of polyurethane 1. 相似文献
177.
Na'il Saleh Mohammed A. Meetani Leena Al-Kaabi Indrajit Ghosh 《Supramolecular chemistry》2013,25(9):650-656
The supramolecular interactions of the ocular drug tropicamide (TR) with cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) were investigated in aqueous solutions by using 1H NMR, ESI-MS and UV–vis spectroscopic techniques. The results indicate a 1:1 binding stoichiometry of TR with CB7 and CB8. The binding constants of TR in its protonated form were higher (e.g. K = 4 × 106 M? 1 with CB8) than in its neutral form (e.g. K = 1.4 × 104 M? 1 with CB8), which led to a complexation-induced increase in its pK a value of ca. 0.5 and 2 units with CB7 and CB8, respectively. In the presence of about 1% (w/v) CB8, the ionisation degree of 0.1% (w/v) TR was increased from 2% to 62% at neutral pH. The increase in the pK a value and thus stabilisation of the protonated TR species at neutral pH is discussed in the context of supramolecular drug delivery of ophthalmologic drugs. 相似文献
178.
Anthracene-appended receptor 1, which can function as an “on–off” fluorescence switch for monocarboxylic acids, has been designed and synthesized. The photophysical behavior of 1 has been examined by fluorescence, UV–vis and NMR spectroscopy. 相似文献
179.
Samaresh Ghosh 《Supramolecular chemistry》2013,25(5):409-414
A novel hyperbranched polyesteramine (PEA) architecture 1 was found to display light-harvesting properties by hosting anthracene-9-carboxylic acid guest 3. The light-harvesting ability has been studied by means of fluorescence spectroscopy. The binding behaviour has also been described by FT-IR and 1H NMR spectroscopic methods. Hyperbranched host 1 also acts as the photon-harvesting chemosensor of the anthracenyl guest over the benzoic acid guest. Furthermore, the host loaded with the anthracenyl guest also exhibited ‘ON–OFF’ switching on protonation of amine sub-units with HCl, thereby making it of potential use as a pH-assisted photon-harvesting material. 相似文献
180.
Samaresh Ghosh & Ajit K. Banthia 《Supramolecular chemistry》2013,25(7):487-494
Novel polyamidoamine (PAMAM) dendrimers (G=0.5–2.5) with a naphthalene core unit have been prepared. They were found to display acid as well as metal ion sensitive fluorescence signal amplification, making them of potential use as chemosensing materials. PAMAM dendritic wedges as well as naphthalene-centered PAMAM dendrimers were characterized by FT-IR, 1H and 13C NMR spectroscopic methods and elemental analysis. 相似文献