@article {46836, title = {Enhancing the mechanical properties of 3D printed polylactic acid using nanocellulose}, journal = {Polymer Engineering and Science}, volume = {60}, year = {2020}, month = {AUG}, pages = {1842-1855}, type = {Article}, abstract = {

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.

}, keywords = {3D printing, Biocomposites, composites, fused filament fabrication (FFF), Nanocellulose, polylactic acid (PLA)}, issn = {0032-3888}, doi = {10.1002/pen.25421, Early Access Date = JUN 2020}, author = {Ambone, Tushar and Torris, Arun and Shanmuganathan, Kadhiravan} } @article {48790, title = {Luminescent 3D printed poly(lactic acid) nanocomposites with enhanced mechanical properties}, journal = {Polymer Engineering and Science}, volume = {63}, year = {2023}, month = {JUL}, pages = {2059-2072}, type = {Article}, abstract = {

The three-dimensional (3D) printing of functional composite materials has gained tremendous interest in recent years. Nevertheless, research on 3D printing of luminescent composite materials is very limited, and the mechanical properties of such 3D-printed composites are poor. Herein, we report the preparation and characterization of a poly(lactic acid) (PLA) composite that, when 3D printed, exhibits enhanced toughness and high solid-state fluorescence quantum yield. Incorporation of only 1 wt\% pyrene butyric acid modified cellulose nanofibers (PBA-m-CNF) and l0 wt\% thermoplastic polyurethane (TPU) into PLA led to 223\% increase in toughness and 21\% increase in tensile modulus of PLA. Scanning electron microscopy (SEM) and X-ray microcomputed tomography (mu-CT) analysis of the fractured cross-sections of 3D printed composites revealed a ductile failure mode. The PLA/PBA-m-CNF1/TPU10 3D printed composite also exhibited a high solid-state fluorescence quantum yield of 38.35\%. To the best of our knowledge, this is the first report to show both enhanced mechanical properties and high solid-state fluorescence emission for 3D printable PLA. Such functional PLA composites could have potential applications in the fabrication of complex-shaped sensors, optical light pipes, etc.

}, keywords = {3D printing, Composite, fluorescence, Nanocellulose, poly(lactic acid), toughness}, issn = {0032-3888}, doi = {10.1002/pen.26345}, author = {Kothavade, Premkumar Anil and Yadav, Prashant and Nidhankar, Aakash D. and Torris, Arun and Pol, Harshawardhan and Kafi, Abdullah and Bateman, Stuart and Sukumaran, Santosh Babu and Shanmuganathan, Kadhiravan} } @article {48758, title = {Thermally activated delayed fluorescent solvent-free organic liquid hybrids for tunable emission applications}, journal = {Chemistry-An Asian Journal}, volume = {18}, year = {2023}, month = {JUL }, type = {Article}, abstract = {

The synthetic feasibility and excellent luminescence features of organic molecules attracted much attention and were eventually found useful in lighting applications. In this context, a solvent-free organic liquid having attractive thermally activated delayed fluorescence features in bulk along with high processability has prime importance. Herein, we report a series of naphthalene monoimide-based solvent-free organic liquids exhibiting cyan to red thermally activated delayed fluorescence with luminescence quantum yields up to 80\% and lifetimes between 10 to 45 mu s. An effective approach explored energy transfer between liquid donors with various emitters exhibiting tunable emission colors, including white. The high processability of liquid emitters improved the compatibility with polylactic acid and was used for developing multicolor emissive objects using 3D printing. Our demonstration of the thermally activated delayed fluorescence liquid will be much appreciated as a processable alternate emissive material suitable for large-area lighting, display, and related applications.

}, keywords = {3D printing, Energy Transfer, OLED, Organic Liquids, TADF}, issn = {1861-4728}, doi = {10.1002/asia.202300276}, author = {Nidhankar, Aakash D. D. and Goudappagouda and Kothavade, Premkumar D. and Dongre, Sangram D. and Veer, Sairam Dnyaneshwar and Dash, Soumya Ranjan and Rajeev, Kavya and Unni, K. N. Narayanan and Shanmuganathan, Kadhiravan and Babu, Sukumaran Santhosh} } @article {49069, title = {Highly electrostrictive salt cocrystal and the piezoelectric nanogenerator application of its 3D-printed polymer composite}, journal = {ACS Applied Materials and Interfaces }, volume = {16}, year = {2024}, month = {MAY}, pages = {26406-26416}, type = {Article}, abstract = {

Ionic cocrystals with hydrogen bonding can form exciting materials with enhanced optical and electronic properties. We present a highly moisture-stable ammonium salt cocrystal [CH3C6H4CH(CH3)NH2][CH3C6H4CH(CH3)NH3][PF6] ((p-TEA)(p-TEAH)PF6) crystallizing in the polar monoclinic C2 space group. The asymmetry in (p-TEA)(p-TEAH)PF6 was induced by its chiral substituents, while the polar order and structural stability were achieved by using the octahedral PF6- anion and the consequent formation of salt cocrystal. The ferroelectric properties of (p-TEA)(p-TEAH)PF6 were confirmed through P-E loop measurements. Piezoresponse force microscopy (PFM) enabled the visualization of its domain structure with characteristic {\textquoteleft}{\textquoteleft}butterfly{\textquoteright}{\textquoteright} and hysteresis loops associated with ferro- and piezoelectric properties. Notably, (p-TEA)(p-TEAH)PF6 exhibits a large electrostrictive coefficient (Q(33)) value of 2.02 m(4) C-2, higher than those found for ceramic-based materials and comparable to that of polyvinylidene difluoride. Furthermore, the composite films of (p-TEA)(p-TEAH)PF6 with polycaprolactone (PCL) polymer and its gyroid-shaped 3D-printed composite scaled-up device, 3DP-Gy, were prepared and evaluated for piezoelectric energy-harvesting functionality. A high output voltage of 22.8 V and a power density of 118.5 mu W cm(-3) have been recorded for the 3DP-Gy device. Remarkably, no loss in voltage outputs was observed for the (p-TEA)(p-TEAH)PF6 devices even after exposure to 99\% relative humidity, showcasing their utility under extremely humid conditions.

}, keywords = {3D printing, cocrystals, energy harvesting, ferroelectricity, Piezoelectricity}, issn = {1944-8244}, doi = {10.1021/acsami.4c03349}, author = {Sahoo, Supriya and Panday, Rishukumar and Kothavade, Premkumar and Sharma, Vijay Bhan and Sowmiyanarayanan, Anirudh and Praveenkumar, Balu and Zareba, Jan K. and Kabra, Dinesh and Shanmuganathan, Kadhiravan and Boomishankar, Ramamoorthy} }