02061nas a2200157   4500008004100000022001400041245014500055210006900200260007100269300001600340490000800356520137800364100002001742700001701762856012401779       2013                        eng d  a1520-610600aVariable-temperature time-resolved emission spectra studies of random pyrene urethane methacrylate copolymers with high pyrene incorporation0 aVariabletemperature timeresolved emission spectra studies of ran  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT  a11863-118760 v1173 a<p>A series of random co-polyurethane methacrylate comb polymers with pyrene (Py) and 3-pentadecylphenol (PDP) as pendant units Were prepared by free radical polymerization. The pyrene labeling was varied from 1 to 100 mol %. The excimer emission of these copolymers were studied as a function of both time and temperature using time-resolved emission spectra (TRES) experiments and variable-temperature steady-state fluorescence measurements. Variable-temperature steady-state as well as decay experiments showed that the contribution from excimers via diffusional encounters increased at the cost of pyrene monomer as the temperature increased until similar to 50 degrees C; beyond which nonradiative losses predominated. TRES collected at 25 and 70 degrees C were compared to study the nature and origin of emitting species as a function of pyrene loading. TRES at 25 degrees C dearly indicated the presence of ground state pyrene dimers with emission centered at similar to 435 nm which soon gave way to emission centered around 465 and 485 nm in the time gated spectra collected at higher time intervals. In TRES collected at 70 degrees C, excimer emission centered at 465 and 485 nm was very high even at short time scales. The lowest pyrene loaded polymer PIHPDP-1Py did not exhibit excimer emission in the TRES collected at 25 degrees C as well as 70 degrees C.</p>1 aKaushlendra, K.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/variable-temperature-time-resolved-emission-spectra-studies-random-pyrene-urethane-002655nas a2200289   4500008004100000022001400041245008500055210006900140260000800209490000800217520171400225653001601939653003101955653002201986653001602008653001302024100002902037700002502066700001802091700002302109700002002132700002202152700002302174700003102197700001702228856012002245       2026                        eng d  a1022-135200aVanillin-based recyclable thermosets and their glass fiber reinforced composites0 aVanillinbased recyclable thermosets and their glass fiber reinfo  cJAN0 v2273 a<p>
	The accumulation of end-of-life plastic materials and composite reinforcement waste materials has brought much attention to developing sustainable alternatives and their re-processability. Incorporating covalent adaptable networks (CANs) into the crosslinked network bridges the concept of reversibility into the otherwise conventional non-reversible networks. This study investigates the structure-property relation in two reversible hardener systems derived from vanillin using Schiff base chemistry. The ``CAN'' systems were synthesized by condensation of vanillin with two amines, 4,4'-oxydianiline and tris(2-aminoethyl)amine, respectively, to form Va_ODA and Va_TAEA. The epoxy thermosets exhibited glass transition temperatures (T-g) of 125 degrees C and 115 degrees C, respectively, for Va_ODA and Va_TAEA, which is superior to most reversible vanillin-based systems reported. The vitrimer-thermosets exhibited promising mechanical and thermal properties, and reshaping abilities as a function of applied temperatures, indicating the dynamic nature of linkages. Chemical degradability was demonstrated by heating to 80 degrees C for 12 h in aqueous acidic medium or excess amine. The fabricated glass fiber composites exhibited good mechanical properties with tensile strength of 361 MPa and degradability in acetic acid/water mixture with a fiber recovery of &gt;98 %. The recovered glass fiber exhibited almost similar tensile strength as the virgin glass fiber, demonstrating its potential reusability. The epoxy vitrimers underwent mechanical reprocessing through hot-pressing, as well as chemical reprocessing via 3D printing and by regeneration of imine bonds to form an epoxy resin.</p>
10a3D printing10acovalent adaptable network10are-processability10aSchiff base10aVanillin1 aVeetil, Ashwani, Puthiya1 aRavikumar, Aniruddha1 aRajput, Tejas1 aSingh, Aman, Kumar1 aThakur, Tamanna1 aKrishna, Abhijith1 aPol, Harshawardhan1 aShanmuganathan, Kadhiravan1 aAsha, S., K.  uhttps://library.ncl.res.in/content/vanillin-based-recyclable-thermosets-and-their-glass-fiber-reinforced-composites