Fabrication of speedy and super‐water‐absorbing non‐woven cloth with hierarchical three‐dimensional network structure

A novel speedy and super‐water‐absorbing non‐woven cloth with hierarchical three‐dimensional network (3D‐SS‐PET) was fabricated through the induction of UV copolymerization on polyethylene terephthalate (PET) fibers followed by a volume phase transition. The macroscopic three‐dimensional network implied that the PET non‐woven substrates are complicated three‐dimensional fibrous materials including oriented fibers in preferential or random directions. The microscopic three‐dimensional network is poly(acrylic acid‐co‐acrylamide) (poly(AA‐co‐AM)) crosslinked copolymer layers on the fiber surface. The rapid volume phase transition was achieved by immersing the swelled non‐woven poly(AA‐co‐AM) modified PET (PET‐g‐AA‐co‐AM) in ethanol. The above process was an essential step to prepare the copolymer chain; after that the fiber surface was extended to form abundant capillary channels and plenty of space between fibers. The water contact angle decreased remarkably from 130° to 0°, while the absorbing capacity of the saturated water and the average water‐absorbing rate experienced an increasing trend, rising from 300 to 324.6 g g^?1 in 24 h and 18.6 and 222 g (g min)^?1 in 40 s, respectively. It was concluded that surface hydrophilicity and capillaries of the hydrophilic modified macroscopic fibrous structure enhanced the water‐absorbing rate and the swelling process contributed to the higher water absorption capacity. This speedy and super‐water‐absorbing material exhibits great potentiality in diapers, sanitary napkins, wound dressings, surgical pads, and hygroscopic and sweat‐free underwear in extremely cold areas. © 2018 Society of Chemical Industry     

Epoxy composite reinforced with three‐dimensional polyimide fiber felt: Fabrication and tribological properties investigation

Novel epoxy (EP) composite reinforced with three‐dimensional (3D) polyimide (PI) fiber felt (PI_3D/EP) is first fabricated by vacuum assisted resin transfer molding. The tribological behaviors of pure EP and PI_3D/EP composite under dry sliding and water lubricated condition are comparatively studied. Results indicate that both wear rates and friction coefficients of PI_3D/EP composite are lower than those of pure EP. The wear resistance of PI_3D/EP composite is 9.8 times higher than that of pure EP under dry sliding of 1.5 MPa and 0.76 m s^?1 while a 27‐fold increase is achieved under water lubricated condition. The wear mechanisms of PI_3D/EP composite are investigated based on tribological testing results and scanning electron microscopy observations. The PI fiber felt provides strong 3D structure supports to sustain most of the loads on the composite, improving the mechanical and tribological properties significantly. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44160.     

Pervaporation properties of a three‐layer structure composite membrane

A novel composite membrane with a three‐layer structure has been prepared. The top layer is a thin dense film of chitosan crosslinked with glutaraldehyde, and the support layer is made of microporous polyacrylonitrile (PAN). Between the dense and the microporous layer, there is an intermolecular crosslinking layer. The performance data show that this is an excellent pervaporation membrane for alcohol dehydration and one‐stage separation is attainable for some alcohol/water mixtures such as ethanol/water and isopropanol/water systems, which has a good separation factor of 1410 and a good flux of 0.33 kg m⁻² h⁻¹ for the EtOH/H₂O mixture, and 5000 and 0.43 kg m⁻² h⁻¹ for the i‐PrOH/H₂O mixture using 90 wt % alcohol concentration at 70°C.Using 90 wt % methanol aqueous solution at 60°C, a flux of 0.17 kg m⁻² h⁻¹ and selectivity of 123 are also obtained. The structure and performance of the novel composite membrane varies with conditions of membrane preparation, such as hydrolysis degree of PAN membrane, content of crosslinking agent, and heat‐curing temperature. The results indicate that the separation factor and the permeation rate of this novel composite membrane increase with the increase of operating temperature. At the same time, the pervaporation properties can be adjusted by changing the structure of the top layer and the middle layer. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 740–745, 2000     

Nanogrooved carbon microtubes for wet three‐dimensional printing of conductive composite structures

Recent advances in three‐dimensional (3D) printing have enabled the fabrication of interesting structures which are not achievable using traditional fabrication approaches. The 3D printing of carbon microtube composite inks allows fabrication of conductive structures for practical applications in soft robotics and tissue engineering. However, it is challenging to achieve 3D printed structures from solution‐based composite inks, which requires an additional process to solidify the ink. Here, we introduce a wet 3D printing technique which uses a coagulation bath to fabricate carbon microtube composite structures. We show that through a facile nanogrooving approach which introduces cavitation and channels on carbon microtubes, enhanced interfacial interactions with a chitosan polymer matrix are achieved. Consequently, the mechanical properties of the 3D printed composites improve when nanogrooved carbon microtubes are used, compared to untreated microtubes. We show that by carefully controlling the coagulation bath, extrusion pressure, printing distance and printed line distance, we can 3D print composite lattices which are composed of well‐defined and separated printed lines. The conductive composite 3D structures with highly customised design presented in this work provide a suitable platform for applications ranging from soft robotics to smart tissue engineering scaffolds. © 2019 Society of Chemical Industry     

Controlling three‐dimensional ice template via two‐dimensional surface wetting

Directional freezing (DF) is a fast, scalable, and environmental friendly technique for fabricating monoliths with long‐range oriented pores, which can be applied toward a wide variety of materials. However, the pore size is typically larger than 20 μm and cannot be spatially controlled, which prevent the technique from being used more widely. In this work, effect of wettability of the freezing substrate on the pore size of monolithic polyethylene glycol cryogels is studied. Smaller pores can be generated via more hydrophilic substrates, and tubular pores smaller 5 μm can be created using a poly(vinyl alcohol) coated copper substrate. A numerical fitting between water contact angle of the substrates and pore size is then obtained. Moreover, pore size can be locally varied duplicating wetting patterns of the substrates. The concept of using two dimensional patterns to build monoliths with three dimensional microstructures can probably be extended to other material systems. DF is an effecient and scalable processing method for fabricating materials with long‐range oriented pores. However, the smallest pore feature size reported is around 20 µm, which is in many cases too large for application such as separation and catalysis. We show here, with exemplary cryogels, that both spatial control and feature size reduction (by one order of magnitude) can be realized in DF by controlling the wettability of the ice growth substrate. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4186–4192, 2016     

Photopolymer resins for luminescent three‐dimensional printing

Liquid resins‐based three‐dimensional (3D) printing techniques such as stereolithography and digital light processing (DLP) show higher resolution and accuracy than other printing techniques, but their applications have been impeded by the limited materials selection and lack of functions. We here reported the preparation of luminescent resins for DLP‐based 3D printing. Homogeneous dispersion of the fluorescent dyes was achieved by small acrylate molecules screening, and the cure depth studies was used to optimize both resin composition and printing parameters setting. In addition, we showed that the optical analysis of absorption and emission spectra is an important tool to reduce the complex mutual‐interference of the light absorption of dye, photoinitiator and photo‐absorber in the printable resin. We also developed the mater batch technique to tune the emitting colors in the whole visible range, together with white emitting. By using the developed resins, different 3D structures with different emitting colors were successfully printed by DLP technique. These results will further widen the applications of the liquid resins‐based 3D printing techniques, and these luminescent resins show highly potential applications in education, lighting, UV converters, and so on. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44988.     

Electrospun three‐dimensional silk fibroin nanofibrous scaffold

Practical application to three‐dimensional (3‐D) tissue culture has been limited by the structural restriction of two‐dimensional (2‐D) nature of electrospun nanofiber mat. In this study, for constructing 3‐D nanofibrous structure as real 3‐D tissue engineering scaffold, we developed new fabrication process with silk fibroin (SF) by electrospinning and evaluated the features of this SF nanofiber scaffold (SFNS) through morphological and cell‐culture analyses. Foam type of the SFNS exhibited high porosity as well as large pores and its cell proliferation well occurred inside (inner spaces of pores), which makes this suitable for 3‐D cell‐culture scaffold. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Moisture sorption of a three‐dimensional braided carbon fiber–epoxy composite under different media

A three‐dimensional braided carbon fiber–epoxy (C_3D/EP) composite was prepared by the vacuum‐assisted resin transfer molding (VARTM) technique. Its moisture absorption behavior under different media was characterized and compared with a unidirectional composite. Similar to the unidirectional composite, diffusion in the 3D composite obeys Fick's second law of diffusion when immersed in distilled water and phosphate‐buffered saline. In HCl and NaOH solutions, no Fickian behavior was observed. The similarity between the unidirectional and 3D composites suggests that fiber structure does not change diffusion pattern. However, the two composites showed different diffusion parameters (k, D, and M_e) in each medium studied. The 3D composite showed lower k, D, and M_e values because of its stronger hindrance effect to transport of moisture molecules. Diffusion in PBS is slower than that in distilled water because of the presence of heavy ions, but the diffusion pattern remains unchanged. In HCl, the diffusion behavior of the two composites cannot be described by Fick's law. In addition, the k value calculated from the initial linear part of the moisture sorption curve is much lower than that in distilled water. Diffusion in NaOH is unusual; the uptake initially increases rather rapidly but quickly drops, which is likely caused by the extensive solubility of the polymer matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 507–512, 2005     

Synthesis and properties of click coupled graphene oxide sheets with three‐dimensional macromolecules

A facile click chemistry approach to the functionalization of three‐dimensional hyperbranched polyurethane (HPU) to graphene oxide (GO) nanosheets is presented. HPU‐functionalized GO samples of various compositions were synthesized by reacting alkyne‐functionalized HPU with azide‐functionalized GO sheets. The morphological characterization of the HPU‐functionalized GO was performed using transmission electron microscopy and its chemical characterization was carried out using Fourier transform‐infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X‐ray photoelectron spectroscopy. The graphene sheet surfaces were highly functionalized, leading to improved solubility in organic solvents, and consequently, enhanced mechanical, thermal, and thermoresponsive and photothermal shape memory properties. The strategy reported herein provides a very efficient method for regulating composite properties and producing high performance materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43358.     

Synthesis and optical properties of poss‐based oxadiazole nanohybrids with three‐dimensional molecular conjugated structure

A series of oxadiazole‐containing molecular hybrid materials with three‐dimensional structure ( P1–P3 ) was prepared by Heck reaction based on the octavinylsilsesquioxane. All resultant hybrid materials are soluble in common organic solvents and possess good film‐forming property. Their structures and properties were characterized and evaluated by FTIR, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, MALDI‐TOF, UV–vis, photoluminescence (PL), cyclic voltammetry, and elemental analysis (EA). The results showed that the substituted arm numbers of hybrids ( P2 and P3 ) with pushing electron groups were efficiently controlled. Moreover, the hybrids possessed a steady blue emission and good electron‐injecting property in film. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40246.     

Ionic‐liquid‐assisted three‐dimensional caged silica ablative nanocomposites

In this study, we demonstrated a novel three‐dimensional network of thermally stable fumed silica (FS)–resorcinol formaldehyde (RF) nanocomposites via an ionic‐liquid (IL)‐assisted in situ polycondensation process. The study involved subjecting the tailored nanocomposites to thermogravimetric analysis and oxyacetylene flame environment as per ASTM test standards for thermal ablative performance. X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high‐resolution transmission electron microscopy, Raman spectroscopy, and wettability studies were undertaken to underline the improvement correlation in the microstructure and material properties. Significant reductions in the linear ablation rate (66%) and mass ablation rate (26.6%), along with lower back‐face temperature profiles, marked enhanced ablative properties. The increased char yield (33.3%) and higher temperatures for weight losses evinced the improved thermal stability of the modified RF resin. The uniformly dispersed fused nanosilica with a glassy coating morphology on the ablative surface acted as barrier to oxidation. The results signify that the IL‐assisted modification of the RF resin with FS significantly enhanced ablative performance. A viable replacement to the conventional phenolic nanocomposites for thermal ablative applications to buy critical time for the containment and suppression of thermal‐heat‐flux threats is of paramount importance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45328.     

Colour appearance in immersive three‐dimensional virtual environments

Technology is constantly evolving and, consequently, all the technological advances taking place are regularly integrated into the daily life of society. During recent years, there has been a trend towards virtual resources such as teleworking, telemedicine and e‐commerce. In many countries, this virtualisation process has been accelerated by the changing circumstances caused by the COVID‐19 pandemic. In any case, there is a growing demand for virtual systems, and virtual reality is a suitable field for the application of a multitude of solutions. However, advances in virtual reality occur without any regard to colour science, and there are several challenges to be overcome to improve the visual appearance and fidelity of colour reproduction in all types of related devices. This paper discusses three open issues related to the visual appearance and visual fidelity of virtual reality systems. We believe it is necessary to direct future research efforts in each of these directions to secure improvements in the visual fidelity of virtual reality systems.     

Assessing the affective feelings of two‐ and three‐dimensional objects

The aim of this study is to investigate the impact of physical appearance attributes (in terms of color and shape) on our affective feelings of 2D and 3D objects. Twelve colors were studied, each consisting of 12 two‐dimensional and 12 three‐dimensional shapes. This resulted in 144 2D and 144 3D color‐shape combinations. Each color‐shape combination was assessed using 20 emotion scales in a viewing cabinet by a panel of observers with normal color vision. The results show that there are five underlying factors of these 20 scales, i.e., “activity,” “weight,” “heat,” “softness,” and “complexity”. The first three factors were mainly related to color and the other two were linked with shape. © 2008 Wiley Periodicals, Inc. Col Res Appl, 34, 75–83, 2009.     

Experiments and progressive damage analyses of three‐dimensional full five‐directional braided composites under three‐point bending

Experimental and numerical studies on the bending properties of three‐dimensional full five‐directional (3DF5D) braided composites are presented in this article. Three‐point bending tests of the braided specimens with different braiding angles were first preformed. Then, the full‐scale specimen model was constructed and a strength analysis method based on repeated unit‐cell (RUC) model was established to describe the strength characteristics of the 3DF5D braided composites. The differences between yarn configurations in corner, surface and interior RUCs were considered and continuum damage models were introduced into the components such as yarns and matrix of the RUCs in the method. This linked the macroscopic nonlinear response with the damages in the microstructures. Good agreements were achieved in the load‐deflection curves and damage morphology between experimental and numerical results. POLYM. COMPOS., 37:2478–2493, 2016. © 2015 Society of Plastics Engineers     

Identification and characterization of three‐dimensional turbulent flow structures

Many phenomena in chemical processes for example fast mixing, coalescence and break‐up of bubbles and drops are not correctly described using average turbulence properties as the outcome is governed by the interaction with individual vortices. In this study, an efficient vortex‐tracking algorithm has been developed to identify thousands of vortices and quantify properties of the individual vortices. The traditional algorithms identifying vortex‐cores only capture a fraction of the total turbulent kinetic energy, which is often not sufficient for modeling of coalescence and break‐up phenomena. In the present algorithm, turbulent vortex‐cores are identified using normalized Q‐criterion, and allowed to grow using morphological methods. The growth is constrained by estimating the influence from all neighboring vortices using the Biot‐Sawart law. This new algorithm allows 82% of the total turbulent kinetic to be captured, at the same time the individual vortices can be tracked in time. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1265–1277, 2016     

Munsell reflectance spectra represented in three‐dimensional Euclidean space

In this article we describe the results of an investigation into the extent to which the reflectance spectra of 1269 matt Munsell color chips are well represented in low dimensional Euclidean space. We find that a three dimensional Euclidean representation accounts for most of the variation in the Euclidean distances among the 1269 Munsell color spectra. We interpret the three dimensional Euclidean representation of the spectral data in terms of the Munsell color space. In addition, we analyzed a data set with a large number of natural objects and found that the spectral profiles required four basis factors for adequate representation in Euclidean space. We conclude that four basis factors are required in general but that in special cases, like the Munsell system, three basis factors are adequate for precise characterization. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 182–196, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10144     

Through‐thickness embossing process for fabrication of three‐dimensional thermoplastic parts

The standard embossing process is limited to the fabrication of surface structures on relatively large polymer substrates. To overcome this limitation, a hybrid punching and embossing process was investigated for through‐thickness embossing of three‐dimensional parts. The embossing tool included a punching head and to‐be‐ replicated features in the socket behind the punching head. The built‐in punching head facilitated a through‐thickness action and provided a closed‐die environment for embossing pressure buildup. The method was used to emboss multichannel millimeter waveguides which requires uniform edges and accurate dimensions. With a tool temperature of 140°C, an embossing time of 3 min and a total cycle time of 7 min, discrete 4‐channel waveguides were successfully embossed from a room‐temperature ABS substrate. A computer model was established to study the flow behavior during through‐thickness embossing. It was found that nonisothermal embossing conditions help confine the polymer in the cavity and reduce the outflow into the surrounding region, thus achieving complete fill of the cavity. POLYM. ENG. SCI., 47:2075–2084, 2007. © 2007 Society of Plastics Engineers     

Three‐dimensional color prediction modeling of single‐ and double‐layered woven fabrics

In this research, the three‐dimensional structural and colorimetric modeling of three‐dimensional woven fabrics was conducted for accurate color predictions. One‐hundred forty single‐ and double‐layered woven samples in a wide range of colors were produced. With the consideration of their three‐dimensional structural parameters, three‐dimensional color prediction models, K/S‐, R‐, and L*a*b*‐based models, were developed through the optimization of previous two‐dimensional models which have been reported to be the three most accurate models for single‐layered woven structures. The accuracy of the new three‐dimensional models was evaluated by calculating the color differences ΔL*, ΔC*, Δh°, and ΔE_CMC(2:1) between the measured and the predicted colors of the samples, and then the error values were compared to those of the two‐dimensional models. As a result, there has been an overall improvement in color predictions of all models with a decrease in ΔE_CMC(2:1) from 10.30 to 5.25 units on average after the three‐dimensional modeling.     

Modeling viscoelastic secondary flows in three‐dimensional noncircular ducts

As process capabilities become more advanced, the need to predict flow phenomena at a smaller scale increases significantly. Viscoelastic secondary flows in square ducts were simulated using a finite volume approach. Single mode and multimode Giesekus and Phan‐Thien Tanner (PTT) models were implemented and were able to reproduce full three‐dimensional (3D) flow through a square duct. Results for low density polyethylene (LDPE), polystyrene, and polycarbonate are all in agreement with experiments [Dooley, Viscoelastic flow effects in multilayer polymer coextrusion, PhD Thesis, Technische Universiteit Eindhoven (2002)] as well as numerical results using a finite element method (FEM) and a meshless radial function method (RFM), [Lopez et al., SPE ANTEC Tech. Pap. (2010)]. The mathematical model presented here has shown the potential to model full 3D flow in more complex geometries. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

A comparison of the unidirectional and radial in-plane flow of fluids through woven composite reinforcements

The in-plane flow of fluids through dense fibrous woven reinforcements was studied to aid the development of constitutive models for use in simulations of composite fabrication by resin transfer molding. As a first part of this effort, both one-dimensional and radial flow experiments were conducted with Newtonian fluids in several woven glass fabrics. Analysis of the one-dimensional flow experiments shows that the two experimental techniques are often, but not always, consistent, and both techniques suggest a relationship between the physical structure of the reinforcement and the mathematical structure of the permeability tensor. Preform features at the laminar and interlaminar scales were hypothesized to influence the experimental results.