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Lignin
Published in Antonio Paesano, Handbook of Sustainable Polymers for Additive Manufacturing, 2022
Sutton et al. (2018) proved that modified lignin could be incorporated in resins for VP in larger amounts than unmodified lignin. They took organosolv lignin modified through acylation with methacrylic anhydride, and added 5, 10, and 15 wt% of it to commercial acrylate resins, and prepared new photoactive feedstocks for SL labelled LR5, LR10, and LR15, from lignin/resin and the wt% amount of legnin. Lignin had 86% purity, 2973 mol/g MW, and was extracted from pulp-grade wood chips of hybrid poplar. The acrylate resins were ethoxylated pentaerythritol tetraacrylate (Sartomer SR494), and aliphatic urethane acrylate (Allnex Ebecryl 8210). A resin photoinitiator and a reactive diluent were also added. The commercial resin PR48 resin (Colorado Photopolymer Solutions, USA) was selected as a control. Table 9.7 contains the tensile properties of PR48 and experimental LRs measured on coupons fabricated on a Formlabs Form 1+ printer: all LRs outperformed PR48 in ductility (elongation at break), and generated uniformly fused, and high-resolution prints that featured improved material toughness upon a lower UV dosage. No LR exceeded PR48 in modulus, but LR10 and LR15 surpassed PR48 in strength.
Rapid printing of nanoporous 3D structures by overcoming the proximity effects in projection two-photon lithography
Published in Virtual and Physical Prototyping, 2023
Harnjoo Kim, Rushil Pingali, Sourabh K. Saha
Custom photopolymer resists were synthesised by mixing polyfunctional acrylate monomers, a custom photoinitiator, and a radical inhibitor. The resist comprised a mixture of: (i) a mixture of pentaerythritol tetraacrylate, pentaerythritol triacrylate (PETA), and trimethylolpropane triacrylate that was sourced from Sigma Aldrich and had a refractive index of 1.483, (ii) bisphenol A ethoxylate diacrylate with average Mn ∼468 – EO/phenol 1.5 (BPADA) that was sourced from Sigma Aldrich and had a refractive index of 1.545, (iii) 4,4′-((1E,1′E)-(2-((2-Ethylhexyl)oxy)-5-methoxy-1,4-phenylene)bis(ethene-2,1-diyl))bis(N,N-dibutylaniline) that was procured from a commercial custom chemical synthesis service provider and which was synthesised from precursors as a photoinitiator following known literature procedures (Rumi et al. 2000), and (iv) additional 4-methoxyphenol (MEHQ) as a radical inhibitor. The monomer mixtures (i) and (ii) were mixed in a 35:65 ratio by weight to generate a monomer blend with a refractive index of 1.52 that closely matches the refractive index of the immersion medium of the objective lenses. This index-matched blend was used here to achieve sharp focusing through minimisation of spherical aberrations in the dip-in printing mode wherein the lens is directly dipped into the photoresist during printing (Mettry et al. 2021; Saha et al. 2018). The resists contained 0.1% by weight of the photoinitiator and 500 ppm of additional MEHQ.
Effects of multifunctional acrylates and thiols on the morphology and electro-optical properties of polymer-dispersed liquid crystal films
Published in Liquid Crystals, 2021
Mohsin Hassan Saeed, Yanzi Gao, Le Zhou, Tingjun Zhong, Shuaifeng Zhang, Chenyue Li, Lanying Zhang, Huai Yang
The nematic LC used in this work, SLC1717, was purchased from Shijiazhuang Yongsheng Huatsing Liquid Crystal Co. Ltd., China (TNI = 365 K, Δn = 0.201, no = 1.519). The thiol monomers, Trimethylopropane tris (2-mercaptoacetate) (TTMP = 3SH, 85%), Pentaerythritol tetrakis (2-mercaptoacetate) (PETMP = 4SH, >85%), and Dipentaerythritol hexakis (3-mercaptopropionate) (DHMP = 6SH, 90%), were purchased from J&K scientific Ltd., Tokyo Chemical Industry Co., Ltd. and Frontier Scientific, Inc., respectively. Flexible chain crosslinking agents polyethylene glycol diacrylate (PEGDA 200, 400, 600 & 1000) were purchased from Sartomer. Multi-functional crosslinking agents trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PETTA), and dipentaerythritol penta-/hexa-acrylate (DTTHPA) were obtained from Aladdin Industrial Inc., China. The photo-initiator Irgacure 651 was purchased from Beijing Hongbai Technology Co. Ltd., China. All the materials, chemical structures of which are shown in Figure 1, were used as received without further purification.
Three-dimensional printing of blue-colored zirconia accessories using digital light processing-based stereolithography
Published in Journal of Asian Ceramic Societies, 2021
Yanhui Li, Shengliang Wang, Minglang Wang, Xinyue Zhang, Binwen Lu, Yueliang Wang, Dongdong Dong, Fupo He, Wei Liu, Shanghua Wu
A ball-milling approach was then applied to prepare a uniform photosensitive resin, including ethoxylated pentaerythritol tetraacrylate (PPTTA, Aladdin), 1,6-hexanediol diacrylate (HDDA, Aladdin), di-functional aliphatic urethane acrylate (U600, Aladdin), 1-octanol (octanol, Aladdin), and some other additives. In the next step, blue-colored photosensitive suspensions were prepared. This step involved the mixing of the above resin with the blue-colored 3Y-TZP powder using the ball-milling method for 2 h, and then the optimal photoinitiator, 1 wt% of photosensitive resin, was added to the suspensions. All the suspensions had the same solid content of 28 vol%, which is sensitive to cure properties. Preparation and characterization of the single layer and accessories