Lignin as a High-Value Bioaditive in 3D-DLP Printable Acrylic Resins and Polyaniline Conductive Composite

Abstract

With increasing environmental awareness, lignin will play a key role in the transition from the traditional materials industry towards sustainability and Industry 4.0, boosting the development of functional eco-friendly composites for future electronic devices. In this work, a detailed study of the effect of unmodified lignin on 3D printed light-curable acrylic composites was performed up to 4 wt.%. Lignin ratios below 3 wt.% could be easily and reproducibly printed on a digital light processing (DLP) printer, maintaining the flexibility and thermal stability of the pristine resin. These low lignin contents lead to 3D printed composites with smoother surfaces, improved hardness (Shore A increase ~5%), and higher wettability (contact angles decrease ~19.5%). Finally, 1 wt.% lignin was added into 3D printed acrylic resins containing 5 wt.% p-toluensulfonic doped polyaniline (pTSA-PANI). The lignin/pTSA-PANI/acrylic composite showed a clear improvement in the dispersion of the conductive filler, reducing the average surface roughness (Ra) by 61% and increasing the electrical conductivity by an order of magnitude (up to 10−6 S cm−1) compared to lignin free PANI composites. Thus, incorporating organosolv lignin from wood industry wastes as raw material into 3D printed photocurable resins represents a simple, low-cost potential application for the design of novel high-valued, bio-based products.

Microwave-assisted organosolv extraction for more native-like lignin and its application as a property-enhancing filler in a light processable biobased resin

“…The reinforcing effect of 1 wt% of methacrylated MW-lignin and CE-lignin is in contrast to the findings of a similar study, wherein the incorporation of the same amount of unmodified organosolv lignin in an acrylic resin reportedly resulted in a reduction in tensile strength, Young's modulus, and elongation at break of the printed product. 69 This highlights the effectiveness of the functionalization of lignin with methacrylate moieties to enable lignin to partake in network formation. The influence of these methacrylated moieties on tensile properties is demonstrated in the higher tensile strength and Young's modulus of thermosets with CE-lignin, which is attributed to its slightly larger number of methacrylate groups.…”

Vat Photopolymerization 3D Printing of Hydrogels with Re-Adjustable Swelling

“…Bearing in mind the properties of the 3D printed objects, it is necessary to obtain good adhesion between the layers. To achieve this, the use of layers with sufficient depth is essential, i.e., C d > z, in our case Z = 100, because the stiffness of a polymer at the gel point (or below it) is too low to endure the printing process [ 28 , 39 , 40 ]. This expression equates to a linear line on a semilogarithmic plot of C d on the y -axis versus E max on the x -axis.…”

The Effect of Few-Layer Graphene on the Complex of Hardness, Strength, and Thermo Physical Properties of Polymer Composite Materials Produced by Digital Light Processing (DLP) 3D Printing

“…One of the most promising ways to improve the properties of final products obtained by DLP 3D printing is the use of composite materials [ 3 ]. Metal nitrides [ 4 ], metal oxides [ 5 ], carbon black [ 6 ], lignin [ 7 ], their mixtures [ 8 ], etc., are used as fillers. By combining the properties of the matrix and the filler, researchers obtain final products with higher properties.…”