The synthesis and manufacturing of polymer nanocomposites have garnered interest in recent research and development because of their superiority compared to traditionally employed industrial materials. Specifically, polymer nanocomposites offer higher strength, stronger resistance to corrosion or erosion, adaptable production techniques, and lower costs. The vat photopolymerization (VPP) process is a group of additive manufacturing (AM) techniques that provide the benefit of relatively low cost, maximum flexibility, high accuracy, and complexity of the printed parts. In the past few years, there has been a rapid increase in the understanding of VPP-based processes, such as high-resolution AM methods to print intricate polymer parts. The synergistic integration of nanocomposites and VPP-based 3D printing processes has opened a gateway to the future and is soon expected to surpass traditional manufacturing techniques. This review aims to provide a theoretical background and the engineering capabilities of VPP with a focus on the polymerization of nanocomposite polymer resins. Specifically, the configuration, classification, and factors affecting VPP are summarized in detail. Furthermore, different challenges in the preparation of polymer nanocomposites are discussed together with their pre- and post-processing, where several constraints and limitations that hinder their printability and photo curability are critically discussed. The main focus is the applications of printed polymer nanocomposites and the enhancement in their properties such as mechanical, biomedical, thermal, electrical, and magnetic properties. Recent literature, mainly in the past three years, is critically discussed and the main contributing results in terms of applications are summarized in the form of tables. The goal of this work is to provide researchers with a comprehensive and updated understanding of the underlying difficulties and potential benefits of VPP-based 3D printing of polymer nanocomposites. It will also help readers to systematically reveal the research problems, gaps, challenges, and promising future directions related to polymer nanocomposites and VPP processes.
The recycling acrylonitrile–butadiene–styrene (ABS) copolymers from waste electrical and electronic equipment lightens the burden on landfills and enables us to reuse waste ABS (wABS), promoting environmental sustainability and resource conservation. In this work, the effect of electron beam irradiation on the properties of wABS by adding 1,3-bis(4,5-dihydro-2-oxazolyl)benzene (1,3-PBO) has been studied. Various characterization methods including gel permeation chromatography, Fourier-transform infrared spectroscopy, mechanical properties test, differential scanning calorimetry, and scanning electron microscopy were conducted to investigate the change of relative molecular weight, chemical structure, mechanical properties, glass transition temperature (T
g), and fracture morphology, respectively. Results demonstrated that the incorporation of 1,3-PBO combined with electron beam irradiation led to significant improvements in molecular weight, tensile strength, impact strength, and T
g. Irradiated wABS-PBO reached optimal comprehensive mechanical properties with the dose at 240 kGy. However, higher electron beam irradiation (>240 kGy) significantly reduced the tensile strength due to extensive chain scission. Besides, the fracture surface morphology became coarser with the reinforced intermolecular binding force of irradiated wABS. This study establishes electron beam irradiation as a promising and effective approach for wABS recycling and reuse.
Considering the importance of asymmetric membrane morphology in controlling the performance of various membrane systems as well as the rapid development of membrane technologies in different industries, the control of membrane manufacturing processes and effective parameters is considered an outstanding subject. Therefore, it seems that investigating the rheological properties of polymer solutions, including gelation behavior, viscoelasticity, and their effect on membrane formation, as well as the morphological structure of membranes, such as hollow fiber and flat sheet membranes, is a requirement for the production of asymmetric membranes with desirable properties. One of the most widely used techniques for the preparation of asymmetric membranes is phase separation. Its two main mechanisms are liquid-liquid demixing and solid-liquid demixing, which can affect the morphology of the membranes in the membrane formation process. Therefore, the membrane morphology can be greatly influenced by controlling the phase separation in the early stages. In this study, an attempt has been made to investigate the rheological behavior of polymer solutions and other factors during the membrane fabrication process, affecting the morphological structure of membranes. The principles governing the rheology of polymer solutions, such as shear, elongation, viscosity, and viscoelasticity have a vital role in determining the membrane morphology and separation performance. Due to the interaction of the rheology of polymer solutions and phase separation, the effects of changes in the rheological properties of the phase separation and the formation of membranes with different structures and morphologies are studied. Furthermore, in addition to the analysis of the effect of the relaxation time and gelation mechanisms, discussions are provided for the determination of the final membrane morphology considering the competition between the domain growth and gelation rates. Finally, the effect of controlling the rheological behavior and phase separation on the membrane structure and performance was investigated in several membrane applications.
Masoumeh Kianfar, Mir Saeed Seyed Dorraji, Mohammad Hossein Rasoulifard
et al.
Herein, a self-healing waterborne polyurethane (WPU) based on a novel visible light-stimulated healing agent from the aromatic Schiff base family (SBWPU) was synthesized. Moreover, this polymer exhibited remarkable mechanical properties, making it an ideal matrix for the preparation of a new nano-composite coating using hexagonal-boron nitride/graphene oxide/nickel oxide (h-BN/GO/NiO) nano-composite for anti-corrosion applications. SBWPU containing 15 wt % of synthesized healing agent (SBWPU-15) demonstrated favorable healing properties (80.03 %) under a visible light lamp after 24 h (at ambient temperature). SBWPU containing 20 % of the healing agent (SBWPU-20) showed high mechanical properties (20.80 MPa) and an increase in its hydrophobic properties. Additionally, its water absorption rate decreased, making it an attractive option as a polymer matrix for anti-corrosion coating applications. The nano-composite coatings (CSBWPU) were formulated by introducing varying amounts of h-BN/GO/NiO into the SBWPU-20. The coatings displayed an increase in contact angle and a decrease in water absorption rate. The electrochemical impedance spectroscopy (EIS) results revealed that the 0.75-CSBWPU, containing 0.75 % nano-composite, had the highest corrosion resistance (1.58 × 1010 Ω cm2) after 90 days of immersion in seawater. This work offers a potentially helpful concept for developing an eco-friendly, secure, uncomplicated accessibility self-healing polymeric system with controllable mechanical features, which are also favorable for designing novel corrosion protection composite coatings.
Somayeh Rafiei, Davood Soudbar, Minoo Sadri
et al.
This research aims to determine and quantify the radiation shielding characteristics of high-density polyethylene/ tungsten oxide (HDPE/WO3) nanocomposites including the linear attenuation coefficient (μ), mass attenuation coefficient (μ/ρ), half-value layer (HVL) and tenth-value layer (TVL) for photons at various energies using Geant4, XCOM, and experiment. Thus, HDPE was chosen as the polymer matrix. Then, the samples at various concentrations of WO3 nanoparticles (0, 1, 2, 3, 4, 5, 6, and 9.5 wt.%), different graphene oxide (GO) weight percentages (0, 0.25, 0.5, and 1 wt.%), and 10 and 20 wt.% linear low-density polyethylene (LLDPE) were fabricated. An NaI (Tl) scintillation detector was used to measure the shielding quantities using the 201Tl, and 99mTc sources at three energies of 135, 140, and 167 keV. The experimental results demonstrated that the addition of GO and LLDPE to the HDPE matrix resulted in a more uniform sample. Incorporating 20% LLDPE into the HDPE polymer matrix for the 99mTc resulted in an 18% rise in μ compared to pure HDPE. Finally, the experimental results revealed a comparatively good agreement with the Geant4 and XCOM simulations.
In this study, we realized a highly luminescent polyester fiber using a special spinneret orifice comprised of eight C-shaped pores and specific process parameters. A moderate amount of reversible photochromism materials was added along with the specific color masterbatch of suitable materials. With its high light transmittance and reflectance, the fabric has high glossiness and excellent transparency and exhibits dazzling color effects with changes in ambient light intensity. The raw materials used are polyethylene terephthalate (PET) chips with a low melting point of 110–150°C, 0.3–0.5% (active ingredient 30%) masterbatch, and 40–50% (active ingredient 50%) reversible photochromism masterbatch. The following process parameters were also chosen: for the PET chips, the drying temperature was 80–90°C, the drying time was 12–14 h, the masterbatch drying temperature was 70–80°C, the drying time was 8–10 h, the spinning temperature was 220–230°C, the cooling air temperature was 15–17°C, the cooling air speed was 0.45–0.50 m·min−1, the first hot roller temperature was 75–80°C, and the secondary hot roller had the heater turned off.
Today, zeolitic catalysts play an important role in catalytic processes such as cracking, alkylation, etc. However, shaping these catalysts for industrial applications remains a challenge. Despite extensive research in this area in recent years, the number of studies is limited, and detailed information is scarce. Consequently, this study aims to increase awareness of the challenges associated with catalyst shaping and to contribute to the body of knowledge in this field. Following an introduction to the fundamental concepts and shaping techniques, our focus in this review has been on the binder agent, whereby we have categorized the effects of binders that can influence catalyst performance. We demonstrate that while binders may not necessarily possess catalytic properties, the chemical interaction between the binder and the catalyst, as well as the extrusion process, can significantly impact the physicochemical characteristics of the final catalyst, including its acid characteristics, pore characteristics, distribution of loaded metals, and so on. Moreover, depending on the desired properties of the catalyst, different sequences can be employed to utilize the binder. Finally, we identify research gaps in this domain and present recommendations for future studies.
Polymers and polymer manufacture, Chemical engineering
Composite or reinforced materials, especially in the class of polymers, are becoming prominent materials for the diversified range of engineering and scientific utilities because of their physical, chemical, mechanical, and structural excellences. Indeed, the main credit for the widespread acknowledgment of polymer matrix composites (PMCs) goes to the various types of natural and synthetic reinforcements, which resulted in good interfacial chemistries. However, the intrinsic challenges of traditional manufacturing technologies always presented restrictions in the development of application specific PMCs. Report-edly, with an evolution of three ‐ dimensional printing (3DP) technologies, the applications of PMCs have been transformed as these enabled the production of near ‐ net shapes with high degree of control over the design, reinforcements, and processing parametric while maintaining the waste associated at minimal level. However, the industrial benefits of 3DP technologies for still limited owing to the lack of awareness among the young professionals and industrial-ists. Moreover, the literature available in this regard is either too scattered making it tedious for the professionals to go through or limited to only fundamental concepts. Therefore, the concept of this review paper is to provide brief research ‐ based insights of different 3DP technologies (namely, fused deposition modeling, selective laser sintering, stereolithography, laminated object manufacturing, and inkjet printing), material systems, applications, and the future paradigms of research as a short and precise document.
ABSTRACT Lightweight and high-strength polymer-derived SiOC ceramics with varied lattice structures have been successfully produced using different polysiloxanes as preceramic polymers (PCPs) via photopolymerisation-based digital-light-processing 3D printing and pyrolysis. Photocurable precursor resins were prepared by simple mixing of polysiloxanes with photosensitive acrylate monomers, achieving good flowability and preserving desirable stability under different heating and oscillation conditions. Complex micron-sized structures were manufactured with high precision via the optimisation of polymer formula and printing parameters. The printed PCPs pyrolysed at 600–1000°C preserved fine features with uniform shrinkage. The skeletons were almost fully dense, with smooth and flawless surfaces at macro/micro scale. Porosities and mechanical properties, including apparent compressive strength, elastic modulus, and indentation hardness, were characterised. XRD, FT-IR, Raman spectroscopy, and XPS were used to explore the chemical variations in elements and atomic bonds. High specific compressive strength to density ratios was obtained for the SiOC lattices compared with other porous ceramics.
Polymer matrix composites have generated a great deal of attention in recent decades in various fields due to numerous advantages polymer offer. The advancement of technology has led to stringent requirements in shielding materials as more and more electronic devices are known to cause electromagnetic interference (EMI) in other devices. The drive to fabricate alternative materials is generated by the shortcomings of the existing metallic panels. While polymers are more economical, easy to fabricate, and corrosion resistant, they are known to be inherent electrical insulators. Since high electrical conductivity is a sought after property of EMI shielding materials, polymers with fillers to increase their electrical conductivity are commonly investigated for EMI shielding. Recently, composites with nanofillers also have attracted attention due to the superior properties they provide compared to their micro counterparts. In this review polymer composites with various types of fillers have been analysed to assess the EMI shielding properties generated by each. Apart from the properties, the manufacturing processes and morphological properties of composites have been analysed in this review to find the best polymer matrix composites for EMI shielding.
Multi-walled carbon nanotubes and high-density polyethylene (MWCNTs/HDPE) nanocomposite sheets with (1.0, 0.5, and 0.1) wt.% MWCNT were successfully prepared by coating the MWCNTs on the surface of the matrix particles (HDPE). The sample resistivities of the nanocomposites were investigated in relation to the temperature influence. Several findings could be drawn from these experiments: For instance, among all of the prepared MWCNT/HDPE nanocomposite sheets with (0.1, 0.5, and 1.0) wt. % MWCNT, the electrical resistivity of the 1.0 wt. % MWCNT/HDPE nanocomposite was 33.18 kΩ.m, demonstrating the best electrical conductivity. The resistivities of 0.1 wt. % and 0.5 wt. % samples were found to be 2594 and 372.23 kΩ.m respectively. Also, the measurements of temperature versus electrical conductivity revealed that the rise in temperature causes the electrical resistivity for the MWCNT/HDPE nanocomposites to increase due to the expansion of the distances between the conductive nanofillers (CNT), i.e., the sample resistivity increased under heating due to the thermal expansion of the polymer matrix. For example, the initial electrical resistivity for the 1.0 wt. % MWCNT/HDPE nanocomposite sheet decreased from 36.25 kΩ.m to 33.18 kΩ.m after the heat treatment. Besides, heat treatment could effectively improve the reproducibility of the MWCNT/HDPE nanocomposites. The reproducibility of the 1.0 wt. % MWCNT/HDPE nanocomposite was better than that of the 0.5 wt. % MWCNT/HDPE nanocomposite.
Although poly(vinylidene fluoride) (PVDF) is widely used in the preparation of biomedical devices, bacterial growth on the polymer surfaces reduces the functionality and lifetime of these devices. To overcome this issue, pyridinium group grafted-PVDF (Pyd-PVDF) was added to PVDF. We prepared antibacterial PVDF-based blends with large-quantities through melt-blending of the PVDF and Pyd-PVDF using a twin-screw extruder. The structural, thermal, mechanical, and antibacterial properties of the prepared blends were characterized. The Izod impact strengths and elongations of the antibacterial PVDF-based blends increased with increasing Pyd-PVDF concentration. In contrast, the flexural moduli and tensile strengths slightly decreased with increasing Pyd-PVDF concentration. This is ascribed to the higher intermolecular interactions between PVDF and Pyd-PVDF as well as lower crystallinity of antibacterial PVDF-based blends as a function of Pyd-PVDF. When the antibacterial activities of the blends were determined against E. coli growth, the blends with ≥5 wt% of Pyd-PVDF exhibited 99.99% antibacterial activities.