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Fabrication of a polypropylene immunoassay platform by photografting reaction
摘要： The technology of an immunoassay detection platform is critical to clinical disease diagnoses, especially for developing a medical diagnostic system. A polymer-based immunoassay platform was fabricated on nonwoven fabric polypropylene (PP) using a photografting reaction to graft 2-hydroxyethyl methacrylate (HEMA) and sulfobetaine (SBMA). The antifouling properties of PP-g-P(HEMA-co-SBMA) were investigated by fibrinogen adsorption and platelet adhesion. Carbonyldiimidazole was employed to activate the pendant hydroxyl groups in HEMA moieties and covalently coupled antibody molecules. The detection of the limit of the immunoassay platform was as low as 10pg/mL. Antibody amount and bioactivity affected the availability of antibody and the sensitivity of immunoassay. The immune efficiency was dependent on the strategies of antibody immobilization. The immune efficiency of Au-g-P(SBMA-co-HEMA) and Au-SH surfaces measured by QCM-D was 165% and 35.7%, respectively. The covalently binding antibody via hydrophilic polymer chains as spacers could retain fragment antigen-binding up orientation, maintain the bioactivity of antibody, and mainly improve the accessibility of antibody molecules via adjusting the conformations of polymer chains when the antibodies recognized the antigens. Therefore, grafting hydrophilic polymers, such as zwitterionic PSBMA and reactive PHEMA onto nonwoven fabric PP, and binding antibody by covalent strategy had the potential to be developed as a commercial immunoassay platform.
关键词： QCM-D,Nonwoven fabric polypropylene,photografting,immune efficiency
更新于2025-11-21 11:08:12
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Interferometric investigation of the opto-mechanical and structural properties of iPP/TiO <sub/>2</sub> nanocomposite fibers
摘要： Fibers that missing specific features and functionalities could be innovated and functionalised via nano additives, in particular metal oxides. Titanium oxide (TiO2) nanoparticles have been added to isotactic polypropylene (iPP) to form iPP/TiO2 nanocomposite fibers. Three samples of iPP/TiO2 fibers were extruded at three extrusion speeds 25, 50, and 78 m/min were considered in this study. Mach–Zehnder interferometer was used to assess the changes in the opto-mechanical and geometrical parameters of iPP/TiO2 nanocomposite fibers along the fiber axis. The mechanical drawing device along with Mach–Zehnder interferometer was utilized to stretch the filaments to different draw ratios. The effect of mechanical cold drawing and extrusion speed on the optical and physical characteristics of iPP/TiO2 nanocomposite fibers were determined along the fiber axis. The optical and physical variation along the nanocomposite samples were characterized by measuring their refractive indices, birefringence, refractive index profile along the fiber axis. The diffraction of He–Ne laser beam was used to define the variation of the fiber diameter along the fiber axis through their cross-sectional area and shape. A sample of uniform diameter from neat iPP fibers was used as reference material for studying the variation of the iPP/TiO2 fiber diameter along the fiber axis. As result, the iPP/TiO2 nanocomposite fibers exhibited nonuniform diameters. The dispersion of TiO2 particles in nanocomposite fibers influences the properties' consistency along and across the fiber.
关键词： cold drawing,nanocomposites,birefringence,interferometry,polypropylene fibers
更新于2025-09-23 15:23:52
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Thermally-stable low-loss polymer dielectrics enabled by attaching crosslinkable antioxidant to polypropylene
摘要： Polymer dielectrics with low loss and high-temperature tolerance are extremely desirable as electrical energy storage materials for advanced electronics and electrical power applications. They can allow fast switching rates during power conversion and therefore achieve high power densities without thermal issues. Here we explore polypropylene (PP), the state of the art dielectric polymer, and present an innovative approach to substantially improve the thermal stability and concurrently reduce the dielectric loss of PP. In particular, crosslinkable antioxidant groups, hindered phenol (HP), are incorporated into PP via well-controlled chemical synthesis. The grafted HP can simultaneously serve as radical scavenger and crosslinker, thereby constraining thermally decomposed radicals and charge transport in the synthesized PP-HP copolymer. As a result, the upper-temperature limit of PP-HP is greatly extended to 190 ?C and the electrical loss is even gradually reduced upon thermal annealing. The copolymer after heating under 190 ?C exhibits better dielectric properties than the PP without any thermal treatment. The experimental results indicate that the PP-HP copolymers are promising materials for high temperature, low loss, and high voltage dielectric applications.
关键词： energy storage,crosslinking,hindered phenol antioxidants,functionalized polypropylene,high-temperature low-loss dielectrics,electrical leakage current
更新于2025-09-19 17:13:59
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Microhole Formation Behavior of Polypropylene Film Using CO<sub>2 </sub>Laser Irradiation
摘要： Biaxially oriented polypropylene films produced by simultaneous equi-biaxial stretching to the draw ratio of 4 (cid:186) 4 were perforated by the carbon dioxide laser under various laser fluences up to 426.3 J/cm2. After applying various laser fluences, the irradiated area was observed using a laser scanning confocal microscope. With the increase of fluence, the surface deformation with the formation of a crater surrounded by a doughnut-like rim was firstly observed at the laser fluence of 49.7 J/cm2, followed by the starting of the formation of a microhole surrounded by the rim at 113.7 J/cm2. The diameter of the microhole and the size of the rim increased rapidly with the increase of laser fluence. Mechanisms for the formation of a crater, the opening of a microhole, and the formation of surrounding rim were considered to be related to the surface tension and the shrinkage caused by molecular orientation relaxation. On the other hand, volume loss from the laser irradiated area was negligibly small at the moment of microhole opening, and started to increase rapidly when the fluence reached around 150 J/cm2. The microhole formation behavior was also observed by a high-speed camera. The velocity of microhole opening increased rapidly at first, presumably during the laser irradiation, and then slowed down after the cessation of laser irradiation. Theoretically estimated temperature distribution along the film thickness was compared with the laser perforation behavior. Starting of the deformation of film matched well with the starting of melting of the film surface. Film temperature was lower than the thermal decomposition temperature at the moment of the opening of a microhole, whereas at the moment of the starting of volume loss, film temperature was lower than the decomposition temperature estimated based on the heating rate of laser irradiated area, indicating that the decomposition and vaporization continues for a while after the cessation of laser irradiation.
关键词： microhole formation,molecular orientation relaxation,Polypropylene,laser fluence,CO2 laser,surface tension
更新于2025-09-19 17:13:59
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The Impact of Laser Radiation on Polypropylene Molded Pieces Depending on Their Surface Conditions
摘要： The article presents an analysis of the impact of a laser beam interaction (Nd: YVO4) with selected operational parameters on the quality of graphical marks obtained on the surfaces of polypropylene-molded pieces with di?erent surface textures (variable parameters of the surface layer). Polypropylene test specimens were produced by injection using the original injection mold, which allowed for the obtainment of products with variable surface ?nish parameters determined by the surface condition of the forming cavity. The presented relationship between the parameters of laser performance, the texture of a molded piece surface, the molded piece’s color, and types of masterbatches supporting the marking process allows for the assessment of the e?ciency of graphic symbol application by laser marking. The original evaluation criteria for the conducted process were adopted.
关键词： laser marking,polypropylene,laser marking masterbatch,colorimetry,surface ?nishing
更新于2025-09-19 17:13:59
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Fabrication of Polypropylene Nanofibers from Polypropylene/Polyvinyl Butyral Blend Films Using Laser‐Assisted Melt‐Electrospinning
摘要： Polypropylene (PP) nano?bers, a few hundred nanometers in diameter, are of immense importance in the ?ber industry. This article reports the fabrication of delicate PP nano?bers. Polyvinyl butyral (PVB) was added to PP as a blend component, and a nozzle-free melt-electrospinning system with a line-like CO2 laser melting device was used to manufacture PP nano?bers. We investigated the effect of PVB ratio on ?ber diameter. The addition of PVB was found to be potentially very bene?cial in PP/PVB blends, resulting in improved PP crystallinity and a steady decrease of ?ber diameter with high productivity. The reduction of ?ber diameter was attributed to the decline of viscosity, increase of surface adhesion properties, and polarity of blends due to the inclusion of PVB. To produce PP nano?ber, the PVB was removed from PP/PVB blend ?bers with an ethanol treatment. A drastic drop of PP ?ber diameter followed by ?ber splitting was observed after PVB removal. We obtained PP nano?bers with a diameter as low as 181 (cid:1) 105 nm from the blend ?ber with 90% PVB. Infrared spectroscopy of ?bers demonstrated that PP ?bers from pure polymer and blends showed the same characteristic peaks.
关键词： Polyvinyl butyral,ethanol treatment,Polypropylene,melt-electrospinning,CO2 laser,nano?bers
更新于2025-09-12 10:27:22
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Terahertz Dielectric Spectroscopic Analysis of Polypropylene Aging Caused by Exposure to Ultraviolet Radiation
摘要： Terahertz dielectric spectroscopy is shown to be an effective tool for bench-marking ultraviolet aging of polypropylene. In this, thin-film polypropylene samples exposed to standard artificial ultraviolet radiation in accelerated aging from 1 day to 30 days are closely monitored by a terahertz time-domain spectroscopy system and analyzed using an effective data processing method. It is found that the terahertz absorption of the polypropylene samples is generally weak and the terahertz dielectric constant varies slightly though discernibly during the aging process, with the refractive index decreasing slightly with increasing length of ultraviolet exposure. Nonetheless, the rate of variation of the polypropylene refractive index with increasing terahertz frequency exhibits a drastic inflection around the 15-days aging point and the rate changes suddenly from positive value to negative value. Based on this prominent and consistent THz dielectric spectroscopic feature of the aging process, an efficient judging criterion is established to distinguish the early-term, mid-term, and late-term phases as well as the degree of polypropylene ultraviolet aging, corresponding to the fundamental transformation of the polymer material from a nonpolar to a polar substance at a critical level of oxidation induced by ultraviolet radiation.
关键词： ultraviolet aging,polypropylene,THz dielectric spectroscopy
更新于2025-09-12 10:27:22
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Prediction of Weld Interface Depth and Width at Optimum Laser Welding Temperature for Polypropylene
摘要： In this preliminary research, Through Transmission Laser Welding (TTLW) of polypropylene is systematically studied through finite element method (FEM) and response surface methodology (RSM) combined approach. The thermal field simulated by solving a three-dimensional transient heat diffusion equation using COMSOL Multiphysics. Statistical software Minitab v17 has been used to develop an experimental design as per central composite design. The objective of the work is in twofold. The first objective of the study aims to develop mathematical models to predict the weld interface depth (MD), weld interface width (MW) and maximum temperature (Tmax), primarily in terms of the process line-energy. The developed mathematical models are examined by analysis-of-variance (ANOVA) technique to check their adequacy. The second objective of the study is to establish an optimised combination of laser welding parameters (laser power, scanning speed and spot diameter) to prevent polypropylene thermal degradation. The desirable MD and MW conditions have been predicted for the established optimised set of laser welding parameters. The results from this preliminary investigation using a FEM approach, can provide the basis for future design of experiments to help predict and obtain enhanced weld quality for polypropylene specifically and other polymer material system in general.
关键词： polypropylene,finite element method,response surface methodology,through transmission laser welding,weld bead dimensions
更新于2025-09-12 10:27:22
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018 –ECCE Asia) - Niigata, Japan (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Optimized Selection and Utilization of DC-Link Capacitor in a Single-Phase PV Grid Inverter System
摘要： Single-phase PV grid inverters usually require large reservoir capacitors on the DC-Link to absorb 2nd order harmonics. This paper shows in a design how to improve the utilization of metalized polypropylene film capacitor (MPFC) specifications in multiple dimensions simultaneously: break-down voltage rating, capacitance, ripple current capability and warranted reliability performance. As a result, the system size and cost can be reduced, while the overall energy capturing efficiency is guaranteed. Under low-capacitance conditions the DC-Link voltage varies within a fundamental cycle; a boost converter is placed between the PV panel and the DC-Link to provide MPPT (maximum power point tracking). The modulation index of the output inverter can be dynamically varied for waveform compensation. Comparison is made with electrolytic capacitors and it is found that when using an optimized capacitor selection strategy, it is possible to mitigate the increased size and cost implications of film capacitors. Simulation demonstrates the design of a 2.5kW system, while experiment is conducted to prove the design concept.
关键词： size reduction,metalized polypropylene film capacitor,reliability,cost,PV inverter
更新于2025-09-09 09:28:46
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Luminescent Properties of Nanocomposites on the Basis of Isotactic Polypropylene and Zirconium Dioxide Nanoparticles
摘要： At the paper studied luminescent properties of nanocomposites on the basis isotactic polypropylene and zirconium dioxide nanoparticles. Shown that change of nanocomposite colour and maximum amplitude of UV spectres depend on ZrO2 nanoparticles sizes in polypropylene. Found that mean-square roughness of PP +1% ZrO2 composition surface in dependence of cooling rate β changes, i.e. for the samples at regime β1=20 deg/min the roughness is 40-60 nm, whereas for the samples prepared at β2=2 deg/min the roughness is 150-220 nm. Shown that polypropylene matrix works as chemically stable preservative of nanoparticles, preserving its spectral peculiarities. Sufficiently strong interphases interactions between PP matrix and ZrO2 nanoparticles change its luminescent properties.
关键词： Photoluminescence,Polypropylene,Zirconium dioxide,Nanocomposite
更新于2025-09-09 09:28:46