3D printing of fiber-reinforced thermoset composites is desirable for rapid fabrication of 3D composite objects with minimal tooling. One of the main issues in 3D printing of thermoset composites is the low cure rates of matrix resins, which prevents rapid curing and rigidization of composite materials during the printing process and capturing the desired print geometry. Here, we demonstrate a new technique for in situ printing and curing of carbon-fiber-reinforced thermoset composites without any postcuring or postprocessing steps. Upon extrusion and deposition of the composite ink from a printing nozzle, the ink is cured via frontal polymerization, leading to rapid printing of high-quality composites. Tailoring the processing conditions allows for freeform or rapid, supported printing of 3D composite objects with zero void content and highly oriented carbon fiber reinforcements.

Molecular imprinting is an efficient tool for generating synthetic acceptors with specific recognition sites, which are mimed from template structures via polymerization. The final products of this strategy lead to high‐performance polymers with active recognition sites for a range of various applications in terms of extraction and separation, characterization and recognition, biomedicine, biosensors, and drug delivery. Molecular imprinting of biomacromolecules synthesizes a series of matrices that may be referred to as biomolecularly imprinted polymers (BMIPs). In this review article, an overview of different methods for fabricating BMIPs with an emphasis on novel polymerization schemes along with potential challenges is discussed. Additionally, selected applications of BMIPs will be briefly highlighted derived from the latest research papers. Copyright © 2016 John Wiley & Sons, Ltd.

Hybrid clay polymer nanocomposites (CPNs) based on blends of natural rubber (NR) and chloroprene rubber (CR) with different compositions (100/0, 95/5, 90/10, 85/15, 80/20), reinforced with various contents of organomodified montmorillonite (OMMT), were prepared by a two-roll mill via a vulcanization process. Curing data of the prepared compounds indicated a reduction in scorch time (t 5 ) and optimum cure time (t 90 ) with increasing the nanoclay content. Mechanical properties of samples were markedly enhanced upon nanoclay inclusion, due to the proper level of interactions established between nanoclay particles and the rubber matrix as it was evidenced by SEM photomicrographs. Results of X-ray diffraction proved the expansion of the interlayer distance, and transmission electron microscopy micrographs further confirmed that the prepared CPN samples exhibit intercalated/partially exfoliated structures. Moreover, the reinforcement effect of OMMT was reflected in the stress-induced crystallization and network structure of the CPNs based on the rubber-elasticity and tube model theories as well as rheological properties. POLYM. COMPOS., 39:1562-1574

Nanostructured heaters based on laser-induced graphene (LIG) are promising for heat generation and temperature control in a variety of applications due to their high efficiency as well as a fast, facile, and highly scalable fabrication process. While recent studies have shown that LIG can be written on a wide range of precursors, the reports on LIG-based heaters are mainly limited to polyimide film substrates. Here, we develop and characterize nanostructured heaters by direct writing of laser-induced graphene on nonuniform and structurally porous aramid woven fabric. The synthesis and writing of graphene on aramid fabric is conducted using a 10.6 μm CO 2 laser. The quality of laser-induced graphene and electrical properties of the heater fabric is tuned by controlling the lasing process parameters. Produced heaters exhibit good electrothermal efficiency with steady-state temperatures up to 170 °C when subjected to an input power density of 1.5 W cm −2 . In addition, the permeable texture of LIG−aramid fabric heaters allows for easy impregnation with thermosetting resins. We demonstrate the encapsulation of fabric heaters with two different types of thermosetting resins to develop both flexible and stiff composites. A flexible heater is produced by the impregnation of LIG− aramid fabric by silicone rubber. While the flexible composite heater exhibits inferior electrothermal performance compared to neat LIG−aramid fabric, it shows consistent electrothermal performance under various electrical and mechanical loading conditions. A multifunctional fiber-reinforced composite panel with integrated de-icing functionality is also manufactured using one ply of LIG− aramid fabric heater as part of the composite layup. The results of de-icing experiments show excellent de-icing capability, where a 5 mm thick piece of ice is completely melted away within 2 min using an input power of 12.8 W.

In thermal frontal polymerization (FP), ambient temperature and staging conditions highly affect the resin behavior and front properties. This study describes the effect of staging conditions and resin reactivity on frontal ring opening metathesis polymerization of dicyclopentadiene in presence of phosphite-inhibited second-generation Grubbs catalyst. An experimental setup is designed to characterize and understand the effect of inhibitor concentration, incubation time, and incubation temperature on front velocity, activation time, and front temperature of the FP reaction. The results reveal that front properties are influenced by various factors, including available energy density of resin, stability of catalyst-inhibitor complex, resin temperature, and resin viscosity. An increase in staging temperature results in lower pot lives but faster gelation process and activation of FP reaction. Additionally, increasing the inhibitor concentration leads to slower fronts, higher activation times, and longer pot lives. The results of this study can be extended to other FP systems and can be used in design of new manufacturing processes and applications using FP.