02018nas a2200241 4500008004100000022001400041245009000055210006900145260000800214300001400222490000700236520121900243653001601462653001801478653001501496653003701511653001801548653002601566100001901592700001701611700003101628856011701659 2020 eng d a0032-388800aEnhancing the mechanical properties of 3D printed polylactic acid using nanocellulose0 aEnhancing the mechanical properties of 3D printed polylactic aci cAUG a1842-18550 v603 a

We report here a systematic investigation of the mechanical properties of polylactic acid (PLA) processed by fused filament fabrication (FFF) 3D printing vs PLA processed by compression molding. Our results show that the tensile strength and modulus of FFF-PLA is 49% and 41% lower, respectively, than compression molded samples of PLA. We also demonstrate here an approach to augment the mechanical properties of 3D printed PLA using nanocellulose. Incorporation of a small quantity (1 wt%) of cellulose nanofibers (CNF) was found to enhance the tensile strength and modulus of 3D printed PLA by 84% and 63%, respectively. X-ray microtomography was used to probe the morphology of 3D printed PLA and PLA/CNF composites. 3D printed PLA/CNF composites had significantly lesser voids as compared to neat 3D printed PLA. Differential scanning calorimetry study revealed that CNF can accelerate the nucleation and crystallization of 3D printed PLA leading to enhanced crystallinity. The thermal stability of 3D printed PLA/CNF composites was not compromised by the addition of CNF. The enhanced mechanical properties of 3D printed PLA/CNF composites can be ascribed to higher crystallinity and lesser defects.

10a3D printing10aBiocomposites10acomposites10afused filament fabrication (FFF)10aNanocellulose10apolylactic acid (PLA)1 aAmbone, Tushar1 aTorris, Arun1 aShanmuganathan, Kadhiravan uhttp://library.ncl.res.in/content/enhancing-mechanical-properties-3d-printed-polylactic-acid-using-nanocellulose02672nas a2200265 4500008004100000022001400041245012700055210006900182260000800251300001400259490000600273520174800279653002502027653002302052653002602075653001402101653001702115653003302132100001502165700002602180700002402206700002102230700003102251856012402282 2020 eng d a2574-096200aEnhancing thermomechanical and chemical stability of polymer electrolyte membranes using polydopamine coated nanocellulose0 aEnhancing thermomechanical and chemical stability of polymer ele cFEB a1988-19990 v33 a

We report here an approach to enhance the chemical and thermomechanical stability of polymer electrolyte membranes without compromising proton conductivity. Multifunctional polydopamine coated nanocellulose (PNC) was prepared by oxidative polymerization of dopamine on nano cellulose fibers and subsequently incorporated in Nafion by solution blending. PNC had a very significant effect on the thermomechanical properties of Nafion showing up to 200% improvement in the storage modulus at 90 degrees C. The PNC network also enhanced the dimensional stability of Nafion under constant stress. The 3 wt % PNC composite membrane showed a drastic reduction in creep compliance of about 39.9% and 46.5% in J(max) at 30 degrees and 60 degrees C, respectively. Free radical scavenging properties of polydopamine also helped to significantly enhance the chemical stability of Nafion, which was ascertained by accelerated degradation tests conducted in Fenton's reagent at 70 degrees C over 40 days. F-19 CP MAS solid state NMR, FTIR, and tensile tests on the membranes show higher chemical stability of the 3 wt % PNC composite membrane. The proton conductivity of the 3 wt % PNC composite membrane at 90 degrees C and 100% RH (similar to 125 mS/cm) was slightly higher than the Nafion membrane (similar to 94 mS/cm) at similar conditions. The retention of proton conductivity even with lower water uptake could be ascribed to proton hopping through polydopamine coated nanocellulose. Performance of the composite membrane was also evaluated in a single stack fuel cell and found to be better than recast Nafion. The benefits derived by this approach are not restricted to Nafion alone and shall broadly apply to many other polymer membranes.

10acellulose nanofibers10achemical stability10adimensional stability10afuel cell10apolydopamine10apolymer electrolyte membrane1 aRam, Farsa1 aVelayutham, Parthiban1 aSahu, Akhila, Kumar1 aLele, Ashish, K.1 aShanmuganathan, Kadhiravan uhttp://library.ncl.res.in/content/enhancing-thermomechanical-and-chemical-stability-polymer-electrolyte-membranes-using02151nas a2200253 4500008004100000022001400041245015200055210006900207260000800276300001400284490000700298520126500305653001201570653001601582653002701598653002201625653002101647100001501668700001801683700001701701700002701718700003101745856012101776 2021 eng d a0969-023900aElastic piezoelectric aerogels from isotropic and directionally ice-templated cellulose nanocrystals: comparison of structure and energy harvesting0 aElastic piezoelectric aerogels from isotropic and directionally  cJUL a6323-63370 v283 a

We report the preparation of highly compressible and elastic piezoelectric aerogels of carboxylated cellulose nanocrystals (CNCs). Aqueous CNC dispersions containing polyethyleneimine and crosslinker were frozen isotropically to yield isotropic aerogels, while oriented aerogels were prepared by directional freezing. These aerogels were highly flexible and porous (similar to 85% void fraction), exhibiting greater than 90% recovery at 50% compressive strain even after 100 compression-decompression cycles. Since such aerogels with low bulk modulus and high anisotropy would be an ideal platform for leveraging the piezoelectric properties of CNCs, we used them to prepare piezoelectric nanogenerator devices and determined their energy transduction behavior. Anisotropic aerogels led to an enhanced open-circuit voltage of 840 mV (at similar to 8 N applied force), which is over 2.6 times higher than isotropic aerogels (320 mV). The energy density of anisotropic aerogels was around 52 nW/cm(2), representing outstanding piezoelectric performance for cellulose-based aerogels. Such aerogels with high compressibility, elastic recovery and exceptional piezoelectric performance could have potential applications in sensors, wearable electronics, etc.

10aAerogel10aAnisotropic10aCellulose nanocrystals10aenergy harvesting10aPiezoelectricity1 aRam, Farsa1 aBiswas, Bipul1 aTorris, Arun1 aKumaraswamy, Guruswamy1 aShanmuganathan, Kadhiravan uhttp://library.ncl.res.in/content/elastic-piezoelectric-aerogels-isotropic-and-directionally-ice-templated-cellulose02486nas a2200277 4500008004100000022001400041245012500055210006900180260000900249300001400258490000600272520153800278653002001816653002001836653003501856653002101891653001401912100002501926700002001951700001901971700002301990700001902013700002002032700003102052856012502083 2024 eng d a2637-610500aEnhancing the crystallization kinetics and mechanical properties of poly(lactic acid) blends for 3D printing application0 aEnhancing the crystallization kinetics and mechanical properties cMAY  a5754-57620 v63 a

3D printing of poly(lactic acid) (PLA) blends has been attempted to resolve issues such as inherent brittleness and slow crystallization rate of PLA. However, a persistent challenge remains in the form of phase separation or gradual migration of the blended soft polymer or plasticizers. To simultaneously enhance the miscibility of the blends and toughness of 3D-printed parts, a triblock copolymer PLA-PEG-PLA was synthesized and blended with PLA in varying proportions (5, 10, 15, and 20 wt %). Blending only 10-20 wt % low molecular weight PLA-PEG-PLA into PLA yielded a miscible blend that showed a 45-fold increase in elongation at break and a 23-fold enhancement in toughness over neat PLA. Scanning electron microscopy (SEM) images of fractured cross sections revealed a brittle to ductile transition in 3D-printed PLA/PLA-PEG-PLA samples. Isothermal crystallization studies and data analysis using the Avrami equation showed an enhancement in the crystal growth rate and overall rate of crystallization. The blends achieved half of their crystallinity in approximately 3 min, a significant improvement over the 9 min required by PLA alone. This underscores the efficiency of our approach. This was also evident in the spherulite growth of 3D-printed PLA and mPLA blends when examined using polarized optical microscopy (POM). To the best of our knowledge, this is the first report exploring the use of blends that include PLA and low molecular weight PLA-PEG-PLA triblock copolymers for 3D printing applications.

10aCrystallization10aFFF 3D printing10aPLA-PEG-PLA triblock copolymer10apoly(lacticacid)10atoughness1 aKothavade, Premkumar1 aYadav, Prashant1 aGopal, Animesh1 aPol, Harshawardhan1 aKafi, Abdullah1 aBateman, Stuart1 aShanmuganathan, Kadhiravan uhttp://library.ncl.res.in/content/enhancing-crystallization-kinetics-and-mechanical-properties-polylactic-acid-blends-3d00867nas a2200229 4500008004100000245011500041210006900156260000800225490000700233653002700240653002500267653003000292653002800322100002500350700001900375700002400394700001800418700003000436700003100466700002000497856012000517 2024 eng d00aExtrusion 3D printing of intrinsically fluorescent thermoplastic polyimide: revealing an undisclosed potential0 aExtrusion 3D printing of intrinsically fluorescent thermoplastic cOCT0 v1610aAdditive manufacturing10afunctional extrusion10ahigh-performance polymers10athermoplastic polyimide1 aKothavade, Premkumar1 aKafi, Abdullah1 aDekiwadia, Chaitali1 aKumar, Viksit1 aSukumaran, Santhosh, Babu1 aShanmuganathan, Kadhiravan1 aBateman, Stuart uhttp://library.ncl.res.in/content/extrusion-3d-printing-intrinsically-fluorescent-thermoplastic-polyimide-revealing