Dual network agar/P(NIPAm-Am) photonic crystal hydrogel offers a unique combination of structural color, mechanochromic behavior, water retention and solvent identification is presented.
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•Dual-network agar/P(NIPAm-Am) photonic crystal hydrogel with mechanochromic property is successfully synthesized.•The photonic crystal hydrogel exhibits excellent water retention capacity for up to 15 days with maintained structural color.•The photonic crystal hydrogel exhibits multi-responsive properties induced by external environmental stimuli.
Photonic crystal hydrogels are obtained by assembling Fe3O4@C nanoparticles within the agar/P(N-isopropylacrylamide-acrylamide) (agar/P(NIPAm-Am)) dual-networks. The dual-network photonic crystal hydrogel offers a combination of structural color, mechanochromic behavior, water retention, solvent identification features, making it an exciting prospect for applications such as chromogenic display and sensing.
•3-Hydroxy(phenyl)phosphorylpropanoic acid (CEPPA)-based flame retardant.•Fire-safe thermoplastic polyurethane created by silane-containing phosphate.•Flame-retardant mechanism of CEPPA-based ...additive-type flame retardant.
Phosphate is a kind of effective flame retardant for thermoplastic polyurethane (TPU), but it always results in great damage to mechanical properties. Herein, an organic silane-containing phosphonate (CTA-APTES) was prepared by 3-Hydroxy (phenyl) phosphorylpropanoic acid, tyramine and γ-aminopropyl triethoxysilane to simultaneously improve the fire safety and decreasing the mechanical loss of TPU. At the loading of 5.0wt%, TPU/CTA-APTES5 passed the UL-94 V-0 rating, and its limiting oxygen index was 28.5%, reaching the non-inflammable grade. While showing remarkable flame-retardant effect on TPU, just as important, the tensile strength and elongation at break of TPU/CTA-APTES5 were 11.34 MPa and 244.5% respectively, increased by 85% and 1471% compared with those of control sample TPU/CEPPA-TA5, remarkably reducing the damage of phosphate to mechanical properties of the substrate. This work provides an efficient strategy to utilize silane-containing phosphate to fabricate high-performance fire-safe TPU.
•The feasibility of machining of CAHL composite using RTEDµD was established.•The machining time increased with the increase of aramid layers in the CAHL.•Better dimensional accuracy obtained at the ...exit of the micro-holes.•Material removal was assisted by pyrolytic carbon and copper deposition.
This study reports the pioneering investigation on rotary tool-assisted electrical discharge micro-drilling (RTEDµD) of carbon-aramid hybrid laminate (CAHL). The machining times (MT) for fabricating one through-micro-hole (depth: 1500 µm) on the CAHL containing 1, 2, and 3 layers of aramid were 785 s, 800 s, and 840 s respectively. The MT increased by 20 % for the CAHL containing 3 aramid layers compared to carbon fiber reinforced polymer (CFRP). The diameter of the holes was within 730–900 µm and an overcut of 4.28 %–28.57 % was observed.
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As one of the most important categories in the additive manufacturing (AM) field, powder-based techniques, such as selective laser sintering, electron beam melting and selective laser ...melting, utilize laser or electronic beams to selectively fuse polymeric, metallic, ceramic or composite powders layer-by-layer into desired products according to their computer-aided design models. With unique mechanical, thermal, electrical, biocompatible and fire-retardant properties, polymeric composite materials for powder-based AM have been attracting intensive research interests because of their potential for a wide variety of functional applications in aerospace, automobile, marine and offshore, medical and many other industries.
This article provides a comprehensive review of the recent progress on polymeric composite materials, their powder preparation for AM, and functionalities and applications of their printed products. It begins with the introduction of thermoplastic polymers that have been used as the main matrices of the polymeric composites and various composite reinforcements such as metallic, ceramic, carbon-based fillers and polymer blends for strengthening and functionality purposes. Discussion is then made on the processes for manufacturing such polymeric composites into powder form, which include shear pulverization, solution-based methods and melt compounding methods, with a focus on their advantages, limitations and challenges in terms of their productivity and processibility as well as powder printability. Thereafter, the properties and functionalities of the printed products and their various intriguing applications particularly in biomedical (anatomical models, tissue engineering and drug delivery), aerospace, automobile, military, energy and environmental, acoustic devices and sports equipment are highlighted. Finally, this review is concluded with an outlook on polymeric composites for powder-based AM, new opportunities, major challenges and possible solutions.
A promising structural control scheme for modulating molecular nonlinear optical response: NLO response of polymeric chain containing POM cluster as a side-chain pendant increases with increase of ...π-spacers. Display omitted
► DFT calculations have been performed on organoimido-substituted hexamolybdates. ► The studied hybrid composites are proposed to be better entrants for NLO applications. ► This work exhibits the tunable NLO behavior of conjugated polymers containing POM.
A new class of π-spacer conjugated donor–acceptor polyoxometalate (POM) cluster covalently attached to the side chain of conjugated polymer, based on the strong electron-donating hexamolybdate pendant and an electron-withdrawing acceptor moiety (NO2), exhibits large second-order optical nonlinearity. For the first time, the effect of increasing the length of the polyenic π-spacer (CC) in polymeric chain containing POM cluster and the influence of the nature of the acceptor moiety on the second-order nonlinear optical (NLO) properties have been studied by using the TDDFT calculations. An intense long range charge-transfer has been observed in these D-π-spacer conjugation – A compounds where the degree of the intramolecular charge transfer from the donor (hexamolybdate pendant) to the acceptor (end phenyl ring bearing NO2 moiety) has been enhanced through π-spacers which might be responsible for the large NLO responses. The conjugated polymers with POM (hexamolybdate) as side-chain pendant are anticipated to be better entrants for NLO applications as their large first hyperpolarizability make them attractive candidates for nonlinear optical materials. Such polymers may exhibit both efficient charge transfer and efficient charge transporting properties as increased conjugation is amplifying the NLO response. These features provide a rationale for the NLO response of these materials and are attractive for designing new, highly efficient second-order nonlinear optical inorganic–organic polymeric composites.
Compatibilization of polymer blends is performed to obtain synergistic effects in physical and mechanical properties. The present work demonstrates the ability of ...vinyltrimethoxysilane-grafted-ethylene propylene diene monomer rubber (VTMS-g-EPDM) to improve the compatibility between EPDM and polybenzoxazine (PB). EPDM reacted with 5 phr of VTMS showed the highest grafting efficiency as well as a relatively low gel content, and was added to EPDM/PB blends. The addition of 8 phr of compatibilizer to 70/30 (w/w) EPDM/PB reduced the dispersed PB droplet size from 3.1 microm to 800 nm. Effects of various blend compositions at constant dosage of compatibilizer (8 phr) on the swelling behavior and tensile properties of the samples were also studied. The tensile strength increased from 12 to 14.5 MPa upon adding the compatibilizer at 50/50 blend ratio of EPDM/PB; however, the increase in the PB content had no significant impact on the tensile strength in both compatibilized and non-compatibilized samples.
In this present work, a PVA/PVP-blend polymer was doped with various concentrations of neodymium oxide (PB-Ndsup.+3 ) composite films using the solution casting technique. X-ray diffraction (XRD) ...analysis was used to investigate the composite structure and proved the semi-crystallinity of the pure PVA/PVP polymeric sample. Furthermore, Fourier transform infrared (FT-IR) analysis, a chemical-structure tool, illustrated a significant interaction of PB-Ndsup.+3 elements in the polymeric blends. The transmittance data reached 88% for the host PVA/PVP blend matrix, while the absorption increased with the high dopant quantities of PB-Ndsup.+3 . The absorption spectrum fitting (ASF) and Tauc’s models optically estimated the direct and indirect energy bandgaps, where the addition of PB-Ndsup.+3 concentrations resulted in a drop in the energy bandgap values. A remarkably higher quantity of Urbach energy for the investigated composite films was observed with the increase in the PB-Ndsup.+3 contents. Moreover, seven theoretical equations were utilized, in this current research, to indicate the correlation between the refractive index and the energy bandgap. The indirect bandgaps for the proposed composites were evaluated to be in the range of 5.6 eV to 4.82 eV; in addition, the direct energy gaps decreased from 6.09 eV to 5.83 eV as the dopant ratios increased. The nonlinear optical parameters were influenced by adding PB-Ndsup.+3 , which tended to increase the values. The PB-Ndsup.+3 composite films enhanced the optical limiting effects and offered a cut-off laser in the visible region. The real and imaginary parts of the dielectric permittivity of the blend polymer embedded in PB-Ndsup.+3 increased in the low-frequency region. The AC conductivity and nonlinear I-V characteristics were augmented with the doping level of PB-Ndsup.+3 contents in the blended PVA/PVP polymer. The outstanding findings regarding the structural, electrical, optical, and dielectric performance of the proposed materials show that the new PB-Ndsup.+3 -doped PVA/PVP composite polymeric films are applicable in optoelectronics, cut-off lasers, and electrical devices.
Polymer composites based on epoxy resin (EP) were developed from which anatomical models of artificial cortical bone tissue were obtained. The cancellous bone was polyurethane foam. To obtain ...appropriate mechanical properties, the EP was filled with CaCO.sub.3 (50, 60, 70 wt%) and a hybrid filler in the form of a mixture of silica and perlite (3/3, 5/5, 7/7 wt%/wt%). Samples for mechanical testing were obtained by vacuum casting in silicone molds. The influence of the type and amount of filler on the mechanical properties of the composite was demonstrated. CaCO3 had a particularly beneficial effect on hardness, compressive stress, and Young's modulus. The obtained anatomical bone model did not differ from natural bone in terms of structure and properties. This type of implants can be used in orthopedics and veterinary medicine. Keywords: artificial bone, polymer composites, materials used in medicine, fillers, mechanical properties. Streszczenie: Opracowano kompozyty polimerowe na bazie zywicy epoksydowej (EP), z ktorych uzyskano modele anatomiczne sztucznej korowej tkanki kostnej. Koscia gabczasta byla pianka poliuretanowa. W celu uzyskania odpowiednich wlasciwosci mechanicznych EP napelniono CaCO.sub.3 (50, 60, 70% mas.) oraz napelniaczem hybrydowym w postaci mieszaniny krzemionki z perlitem (3/3, 5/5, 7/7 %mas. /%mas.). Probki do badan mechanicznych otrzymano metoda odlewania prozniowego w formach silikonowych. Wykazano wplyw rodzaju i ilosci napelniacza na wlasciwosci mechaniczne kompozytu. Szczegolnie korzystny wplyw na twardosc, naprezenie sciskajace i modul Young'a mial CaCO.sub.3. Otrzymany model anatomiczny kosci pod wzgledem struktury i wlasciwosci nie odbiegal od naturalnej kosci. Tego typu implanty moga znalezc zastosowanie w ortopedii i weterynarii. Slowa kluczowe: sztuczna kosc, kompozyty polimerowe, materialy stosowane w medycynie, napelniacze, wlasciwosci mechaniczne.
The ballistic performance of ultra-high molecular weight polyethylene (UHMWPE) laminated plates and UHMWPE encapsulated aluminum structures were numerically characterized. Full three-dimensional ...continuum model for each type of target was built, and the UHMWPE was simulated using a sub-laminate approach with a composite material model. Simulation results were compared with existing experimental measurements, with good agreement achieved both on final deformation morphology and ballistic data. Underlying penetration mechanisms of laminated plate were then explored, and the effect of interface strength was quantified. The ballistic improvement of UHMWPE encapsulated aluminum structures was mainly attributed to the stretching of lateral swathing laminates. However, the benefit of encapsulation decreased as the initial impact velocity or lateral dimensions of encapsulated structure were increased. These findings are helpful for designing lightweight UHMWPE composite structures with superior ballistic resistance.
Plasticized poly (lactic acid) (PPLA) was prepared by melt blending poly (lactic acid) (PLA) with 10 wt% of poly (ethylene glycol) (PEG), with varied molecular weights range from 400 to 4000. The ...structure, thermal property, morphology, and surface free energy of the PPLA were investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and contact angles (CA). The resulting PPLA results indicated that the introduction of PEG to the blend systems resulted in a ductile fracture, a decrease in the melt temperature (Tm) and glass transfer temperature (Tg), and an increase in the degree of crystallization (χc), which indicated an improved flexibility. In addition, the polarity of the PPLA increased and the surface free energy decreased. The resulting PPLA was subsequently used as matrix to blend with wood flour to prepare composites. The mechanical strength, melting behavior, thermal stability, and microscopy of the PPLA/wood flour composites were also evaluated. These results illustrated that the plasticized PPLA matrix was beneficial to the interfacial compatibility between the polar filler and the substrate.
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