Chain Orientation Research Articles

Market and Supply Chain Orientation; Dynamic Capabilities Leading to Innovation and Operational Capabilities

Market and Supply Chain Orientation; Dynamic Capabilities Leading to Innovation and Operational Capabilities

Creep rapture of plastic pipes: Effect of eccentricity, residual stress, and circumferential orientation

Plastic pipes made of high density polyethylene material with known geometric eccentricities and residual stresses were subjected to long term hydrostatic stress until rupture at different stresses and temperatures. Cooling and crystallisation rates of the pipe wall during the extrusion process were simulated along the production line. Crystallisation profile and circumferential orientation of polymer chains were measured at different angular locations and thicknesses around the circumference. It was shown that the plasticity-controlled rapture times of plastic pipes are significantly depended on geometric eccentricity as a result of re-distribution of residual stresses and circumferential orientation.

Synergistic Effect of Betaines and Dialkyl Chain Anionic Surfactants on Interfacial Arrangement: A Molecular Dynamics Simulation Study.

Mixed systems of betaines and anionic surfactants can have a significant synergistic effect and greatly reduce the interfacial tension (IFT), which has attracted an extensive amount of attention. However, this synergistic effect requires an anionic surfactant and betaine molecular size matching, which limits the scope of its application. In this work, we studied three mixed systems of sodium dialkyl sulfosuccinate (AOT) and betaines with different sizes by molecular dynamics simulation and an IFT experiment and explored the interfacial behavior and synergistic mechanism of AOT in single and mixed systems. The hydrophobic tail chain center angle, average rising height of carbon atoms, stretch degree and distance between the terminal carbon atoms of AOT, and tilt angles of betaine were calculated and analyzed in detail. Simulation results showed that the hydrophobic tail chain center angle of AOT in the single system was smaller, and it tended to extend into the oil phase. After being mixed with different betaines, AOT can adjust its size according to the interfacial vacancies of different betaine systems by changing the alkyl chain orientation and forming tighter interfacial films. The IFT experiment showed that betaine/AOT mixed systems achieved a lower IFT value compared with that of the single system, indicating that AOT showed a synergistic effect with betaines with different structures. This study will be importantly instructively significant for the design and research of betaine mixed systems in crude oil exploitation.

Electrically regulated thermal conductivity of aramid polymer systems

Aramid polymers, renowned for their electronic insulation and thermal conductive properties, are widely adopted as thermal management materials in power electronics. However, the thermal conductivity of aramid polymers under electric field has not been thoroughly understood. In this study, we investigated the thermal conductivity of amorphous and aligned aramid polymer systems under electrical field utilizing equilibrium molecular dynamics simulations. Simulation results showed that the alignment of polymer chain can significantly enhance the thermal conductivity of aramid polymer systems, achieving up to 10.13 W/m-K. Moreover, polarization of aligned aramid polymer was observed when the applied electric field exceeded 14 V/nm. Interestingly, the thermal conductivity of aligned aramid polymer was selectively modulated by the applied electric field. To unravel the underlying phonon mechanism, the molecular orientation of polymer chains and phonon spectral information were analyzed. Our study provides guidance into understanding thermal transport mechanism and thermal conductivity modulation in polymers.

Charge transport and ion migration in perovskite-incorporated conjugated polymer semiconductor

The migration of intrinsic ions in metal halide perovskites and their interfaces has been shown to contribute to hysteresis and performance degradation in perovskite-based electronic devices, particularly in photovoltaics and transistors. Accordingly, controlling the film morphology, microstructure, and ionic defects in perovskite semiconductors is essential for advancing and achieving high-performance perovskite field-effect transistors (FETs). In this study, we demonstrate a well-controlled method to systematically probe the structure-property relationships, origin of hysteresis, and intrinsic ion migration effects in formamidinium iodide and lead iodide (FAI + PbI2)-based perovskite by incorporating it in a semicrystalline conjugated poly(3-hexylthiophene) (P3HT) polymer. Optimized FETs exhibited over 100% hole mobility enhancement owing to unperturbed edge-on crystalline orientation of the P3HT chains caused by the incorporated perovskite, P3HT-(FAI + PbI2) interactions, and better charge injection properties. However, the optimized devices exhibited improved current modulation with dual-sweep hysteresis, which was attributed to the ion migration effect contributed by the polarization of the lead/iodine-related ions and defects. Furthermore, operational stability investigation of the P3HT-(FAI + PbI2) FETs in the air revealed gradual current decay owing to charge trapping in contrast to the control P3HT FETs. This work provides a fundamental understanding of the origin of hysteresis and instabilities in metal perovskite materials and their transistor-based devices.

Highly Thermally Conductive Triple-Level Ordered CNT/PVA Nanofibrous Films.

The escalating thermal power density in electronic devices necessitates advanced thermal management technologies. Polymer-based materials, prized for their electrical insulation, flexibility, light weight, and strength, are extensively used in this field. However, the inherent low thermal conductivity of polymers requires enhancement for effective heat dissipation. This work proposes a novel paradigm, emphasizing ordered structures with functional units, to create triple-level, ordered, low-filler loading of multi-walled carbon nanotube (MWCNT)/poly(vinyl alcohol)(PVA) nanofibrous films. By addressing interfacial thermal resistance through -OH groups, the coupling between polymer and MWCNT is strengthened. The triple-level ordered structure comprises aligned PVA chains, aligned MWCNTs, and aligned MWCNT/PVA composite fibers. Focusing on the filler's impact on thermal conductivity and chain orientation, the thermal transport mechanisms have been elucidated level by level. Our MWCNT/PVA composite, with lower filler loadings (10 wt.%), achieves a remarkable TC exceeding 35.4 W/(m·K), surpassing other PVA composites with filler loading below 50 wt.%.

Mechanically rejuvenated glassy polylactide with spatial heterogeneity and packing efficiency: Time dependence of deformation behavior

Mechanical rejuvenation is effective in conquering the physical aging of polymers, but its molecular origin is far from clear. Herein, glassy polylactide is subjected to mechanical rejuvenation under extensional stress field via “casting-thermal stretching”, and the joint effect of spatial heterogeneity and packing efficiency on the brittle-to-ductile transition is demonstrated. The extensional stress accelerates segmental relaxation and heavily enhances the spatial heterogeneity in activated amorphous fraction. The much larger extensional stress enhances the orientation and packing efficiency of polylactide chains, with the close-packing amorphous fraction restraining the molecular mobility but boosting self-reinforcement. Strong time-dependent deformation behavior is discovered in rejuvenated polylactide, with different draw ratios exhibiting quite different critical strain rates of ductile-to-brittle transition, and that with densified network even maintains high ductility at extremely high strain rate. This work provides new insights into mechanical rejuvenation and significant guidance for the processing of advanced biodegradable polymers.

Unmanned Airborne Bistatic Interferometric Synthetic Aperture Radar Data Processing Method Using Bi-Directional Synchronization Chain Signals

The bistatic Interferometric Synthetic Aperture Radar (InSAR) system can overcome the physical limitations imposed by the baseline of monostatic dual-antenna InSAR. It provides greater flexibility and can enhance elevation measurement accuracy through a well-designed baseline configuration. Unmanned aerial vehicles (UAVs) equipped with bistatic InSAR, having relatively low cost and high flexibility, are useful for mapping and land resource exploration. However, due to challenges including spatiotemporal synchronization and motion errors, there are limited reports on UAV-borne bistatic InSAR. This paper proposes a comprehensive method for processing data from small UAV-borne bistatic InSAR by integrating two-way synchronization chain signals. The proposed method includes compensation for time and phase synchronization errors, trajectory refinement with synchronized chain and Position and Orientation System (POS) data, high-precision bistatic InSAR imaging, and interferometric processing. Height inversion results based on the proposed method are also provided, which demonstrate the effectiveness of the proposed method in improving the accuracy of interferometric measurement at calibration points from 0.66 m to 0.42 m.

Pressure-Driven Piezoelectric Sensors and Energy Harvesting in Biaxially Oriented Polyethylene Terephthalate Film.

This study reports the possibility of using biaxially oriented polyethylene terephthalate (BOPET) plastic packaging to convert mechanical energy into electrical energy. Electricity is generated due to the piezoelectricity of BOPET. Electricity generation depends on the mechanical deformation of the processing aids (inorganic crystals), which were found and identified by SEM and EDAX analyses as SiO2. BOPET, as an electron source, was assembled and tested as an energy conversion and self-powered mechanical stimuli sensor using potential applications in wearable electronics. When a pressure pulse after pendulum impact with a maximum stress of 926 kPa and an impact velocity of 2.1 m/s was applied, a voltage of 60 V was generated with short-circuit current and charge densities of 15 μAcm-2 and 138 nCm-2, respectively. Due to the orientation and stress-induced crystallization of polymer chains, BOPET films acquire very good mechanical properties, which are not lost during their primary usage as packaging materials and are beneficial for the durability of the sensors. The signals detected using BOPET sensors derived from pendulum impact and sieve analyses were also harvested for up to 80 cycles and up to 40 s with short-circuit voltages of 107 V and 95 V, respectively. In addition to their low price, the advantage of sensors made from BOPET plastic packaging waste lies in their chemical resistance and stability under exposure to oxygen, ultraviolet light, and moisture.

Self-Enhancement of Perfluorinated Sulfonic Acid Proton Exchange Membrane with Its Own Nanofibers.

High-performance proton exchange membrane (PEM) is crucial for the proton exchange membrane fuel cell (PEMFC). Herein, a novel "self-enhanced" PEM is fabricated for the first time, which is composed of perfluorinated sulfonic acid (PFSA) resin and its own nanofibers as reinforcement. With this strategy, the interfacial compatibility issue of conventional fiber-reinforced membranes is fully addressed and up to 80 wt% loading of PFSA nanofibers can be incorporated. Furthermore, on account of chain orientation within the PFSA nanofiber, single fiber exhibits super-high conductivity of 1.45 S cm-1, leading to state-of-the-art proton conductivity (1.1 S cm-1) of the as-prepared "self-enhanced" PEM so far, which is an order of magnitude increase compared with the bulk PFSA membrane (0.29 S cm-1). It surpasses any commercial PEM including the popular GORE-SELECT and Nafion HP membranes and is the only PEM with conductivity at 100 S cm-1 level. In addition, the mechanical strength and swelling ratio of membranes are both substantially improved simultaneously. Based on the high-performance "self-enhanced" PEM, high peak power densities of up to 3.6W cm-2 and 1.7W cm-2 are achieved in H2-O2 and H2-Air fuel cells, respectively. This strategy can be applied in any polymeric electrolyte membrane.

Molecular chain orientation and mechanical properties of hydrogenated nitrile-butadiene rubbers with different acrylonitrile content and crosslink density

A study of the thermal and mechanical properties, as well as the molecular chain orientation of sulfur-vulcanized hydrogenated nitrile-butadiene rubber (HNBR) with acrylonitrile (ACN) content of 34 and 36 wt% and different crosslink density is presented. The objective is to establish the relationships between structural changes during stretching and the tensile and elastic behavior of HNBR having different chain microstructure. The (vulcanized) HNBR samples are amorphous at room temperature with glass transition temperatures that increase with increasing ACN content and crosslink density. The samples do not exhibit strain-induced crystallization. Stretching at room temperature only induces orientation of the amorphous segments along the stretching direction, which contributes to improved tensile strength, strain-hardening, and toughness, while preserving excellent elastic recovery of the rubbers. Precise correlations are established between the degree of orientation of the amorphous chain and the deformation in the framework of the affine deformation model of rubber elasticity.

Green supply chain and market orientation: Catalysts for sustainable green knowledge management

The purpose of this study is to concurrently test the effect of green market orientation and green supply chain management on establishing green knowledge management among Malaysian manufacturing companies. To empirically test the model, the authors developed quantitative research by collecting data from 115 manufacturing organisations operating in Malaysia. Partial least squares structural equation modelling was used to analyse the data. The results of the study reveal that green market orientation has a significant and direct positive effect on green knowledge management. Equally, green supply chain management has a direct positive and significant effect on green knowledge management. The findings of this study provide insights for practitioners, academia, and policymakers on how to use the selected variables to improve the sustainability performance of organisations.

Orientation and stretching of supracolloidal chains of diblock copolymer micelles by spin-coating process.

Supracolloidal chains consisting of nano- or micro-scale particles exhibit anisotropic properties not observed in individual particles. The orientation of the chains is necessary to manifest such characteristics on a macroscopic scale. In this study, we demonstrate the orientation of supracolloidal chains composed of nano-scale micelles of a diblock copolymer through spin-coating. We observed separate chains coated on a substrate with electron microscopy, and analyzed the orientation and stretching of the chains quantitatively with image analysis software. In drop-casting, the chains were coated randomly with no preferred orientation, and the degree of stretching exhibited an intrinsic semi-flexible nature. In contrast, spin-coated chains were aligned in the radial direction, and the apparent persistence length of the chain increased, confirming the stretching of the chain quantitatively. Furthermore, by incorporating fluorophores into supracolloidal chains and confirming the oriented chains with confocal fluorescence microscopy, it is demonstrated that oriented chains can be utilized as a template to align functional materials.

Bending of polymer films: a method for obtaining a compressive modulus of thin films.

Due to the advent of various foldable electric devices, it is becoming increasingly important to understand the bending properties of film materials. Bending of isotropic materials may be trivial if elastic deformation is small within a range of linear elasticity, which is often the case for bending. However, bending of polymer films, often used in recent foldable devices, may not be the case. Polymer films are frequently fabricated with stretching, which induces anisotropic orientation of molecular chains. In addition, there are many studies on bimodulus materials, which suggest the importance of the difference in tensile and compressive elastic moduli, i.e., the importance of elastic asymmetry, considering that bending involves compression and extension. In this study, we extended the standard linear elastic theory to include elastic anisotropy and elastic asymmetry and developed a method for obtaining compressive moduli of films, which cannot be obtained by a simple compression test because thin films under compression buckle at small strains. Our method is based on a bending test combined with a uniaxial tension test, which allows the measurement of Poisson's ratio in addition to Young's modulus, which are both anisotropic and asymmetric. To test our theory and method, we further performed experiments on biaxially stretched poly(ethylene terephthalate) (PET) films. As a result, we found non-negligible anisotropy in Poisson's ratio and non-negligible asymmetry (bimodulus) in tensile and compressive moduli. We further justify our framework by demonstrating a clear data collapse to show agreement between experiment and theory, clarifying limitations. Our results suggest the importance of elastic anisotropy and elastic asymmetry in bending of industrial films and give fundamental knowledge on this subject, which would be useful for applications. Such applications include the control of the position of the neutral plane and precise measurements of elastic moduli and Poisson's ratio, which are crucial, e.g., for the development of tough flexible electric devices and for the structural designs using compliant mechanisms.

Preparation of vertically oriented aromatic polyester thin films by thermal chemical vapor deposition

Aromatic polyesters exhibit high thermal conductivity and large nonlinear optical effects by controlling the orientation of their main chains. Especially in recent years, with the development of flexible optical and electronic devices utilizing polymer thin films, out-of-plane orientation control in thin films on the order of several hundred nm is required. However, due to the rigidity of aromatic polyesters, it is difficult to control vertical orientation in thin film growth from melt or solution. In this study, we attempted to control the vertical orientation of aromatic polyester thin films from the vapor phase using a thermal CVD. From a single head-to-tail type monomer, aromatic polyester thin films with the most primitive structure, whose mp exceeds 500 °C, were successfully grown. Furthermore, it was found that the vertical orientation of the main chains was enhanced by substrate surface treatment.

Fabricating multi-scale controllable PEDOT:PSS arrays via templated freezing assembly.

The fabrication of conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) into controllable hierarchical arrays is gaining increasing interest for various applications, e.g., bioelectronics, and regenerative medicine. Currently, solution-based print processing is the main methodology for fabricating PEDOT:PSS arrays. However, its constraints on crystallinity and polymer chain orientation often necessitate intricate post-processing procedures to enhance their material properties. Here, we report the precise control in the assembly of PEDOT:PSS to have customized arrays via a templated freezing assembly strategy (TFA). We can prepare centimeter-scale PEDOT:PSS patterns with tunable micro-morphology, nanofiber width, crystallinity, and polymer chain orientation. Importantly, the refined micro-morphologies endow good stretchability to the obtained arrays, and regulated crystallinity and polymer chain orientation directly lead to adjustable conductivity, ranging from 10-3 S cm-1 to 100 S cm-1. This strategy provides a novel avenue for fabricating conductive polymers into tailored electric devices, suggesting potential applications in flexible electronic devices and beyond.

Evaluation of Myocilin Variant Protein Structures Modeled by AlphaFold2.

Deep neural network-based programs can be applied to protein structure modeling by inputting amino acid sequences. Here, we aimed to evaluate the AlphaFold2-modeled myocilin wild-type and variant protein structures and compare to the experimentally determined protein structures. Molecular dynamic and ligand binding properties of the experimentally determined and AlphaFold2-modeled protein structures were also analyzed. AlphaFold2-modeled myocilin variant protein structures showed high similarities in overall structure to the experimentally determined mutant protein structures, but the orientations and geometries of amino acid side chains were slightly different. The olfactomedin-like domain of the modeled missense variant protein structures showed fewer folding changes than the nonsense variant when compared to the predicted wild-type protein structure. Differences were also observed in molecular dynamics and ligand binding sites between the AlphaFold2-modeled and experimentally determined structures as well as between the wild-type and variant structures. In summary, the folding of the AlphaFold2-modeled MYOC variant protein structures could be similar to that determined by the experiments but with differences in amino acid side chain orientations and geometries. Careful comparisons with experimentally determined structures are needed before the applications of the in silico modeled variant protein structures.

Carbon nanofibers based carbon–carbon composite fibers

Textile grade polyacrylonitrile (PAN) was used as a precursor material for carbon fiber preparation. E-beam irradiated polyacrylonitrile grafted carbon nanofibers were dispersed in polyacrylonitrile solution (dissolved in dimethyl formamide). Carbon nanofibers (CNF) infused polyacrylonitrile solution was wet spun on a lab-scale wet-spinning setup to form 50 to 70 µm diameter fibers with 3.2 wt.% CNF-PAN, 6.4 wt.% CNF-PAN, and neat PAN. Precursor fibers were characterized for thermal, mechanical and morphological properties using various techniques. Drawing the precursor fibers further enhanced polymer chain orientation and coalesced the voids, enhancing tensile strength and modulus by more than 150% compared to those of the undrawn fibers. Precursor composite fibers on carbonization showed enhanced strength, compared to that of pristine PAN fibers, by four times and stiffness by 14 times. The carbon–carbon composite fibers were further characterized with SEM/FIB, XRD and tensile strength. The property improvements were dependent on the uniform distribution of carbon nanofibers, and surface modification of carbon nanofibers further enabled their dispersion in the composite fibers. Furthermore, 3.2 wt.% CNFs in PAN fibers showed maximum improvement in properties compared to 6.4 wt.% CNF in PAN fibers, indicating that the property enhancements go through a maximum and then drop off due to challenge in getting uniform distribution of nanofibers.

Effects of different types of functionalized polypropylenes on the tensile strength of short carbon fiber-reinforced polypropylene composites

In this study, the effects of various functionalized polypropylenes (PPs) with different types and contents of functional groups and crystallinities on the tensile strength of short carbon fiber (SCF)-reinforced plastics (SCFRPs) prepared by injection molding were evaluated. The tensile strengths of SCFRPs were significantly influenced by interfacial adhesion. The types and contents of functional groups introduced into functionalized PP were the dominant factors impacting the development of interfacial adhesion. In particular, near the surface where SCF and PP were highly oriented in parallel, functionalized PP with more functional groups added to side chains exhibited higher interfacial adhesion than that with fewer functional groups. These results suggested that PP molecular chain orientations resulting from the shear flow of injection molding were among the key factors affecting the interfacial adhesion of the PP matrix.

Investigation of the Microstructure of PAN Precursor Fibers Obtained at Various Processing Stages

The production of high-performance carbon fibers relies heavily on the structural transformations of polyacrylonitrile (PAN) fiber during processing. In this article differential scanning calorimetry (DSC), synchrotron small-angle X-ray scattering (SAXS), and synchrotron wide-angle X-ray diffraction (WAXD) were used to study the changes of the thermal properties, voids and crystal structure of the PAN precursor fibers on industrial lines during the continuous processing stages, i.e., after the treatment in the coagulation bath, after stretching in boiling water and after stretching in high-temperature steam. The findings of this study suggest that after boiling water stretching the molecular chain motion of the PAN precursor fiber weaken, resulting in the expansion of the voids. After high-temperature steam stretching the voids became elliptical and oriented in the stretching direction. Although the boiling water stretching process partially damaged the (100) crystal planes of the PAN precursor fibers, it does not hinder their overall crystalline structure. The high stretching ratio primarily affected the orientation of the molecular chains. This orientation, even in the context of partial crystal plane disruption, further promoted the crystallization of the (100) crystal planes in the fibers. These experiments explored the correlation between the processing technology and fiber structure transformation of PAN-based carbon fibers, resulting in producing a guide for the preparation of high-performance carbon fibers with fewer defects.