Particles In Polymer Matrix Research Articles

Additive Manufacturing With Strontium Hexaferrite-Photoresist Composite

Millimeter wave components, such as circulators and isolators, frequently use magnetic fields to break symmetry of the signal propagation and provide unidirectional signal transmission. While effective, these components have not seen the level of miniaturization of other millimeter wave components, primarily due to the discrete nature of the magnets used in the components. Using circulators in the 40-50 GHz range as a motivating application, requirements arise for the deposited films, namely immunity to eddy currents, sufficient magnetization to act as self-biasing magnets, and out-of-plane orientation of the self-biasing field. Based on these required properties, hexaferrite materials are selected for their strong magnetocrystalline anisotropy (MCA) and low conductance. The difficulty of integrating these components monolithically with monolithic microwave integrated circuits (MMIC) originates from the incompatibility of crystal structure with standard semiconductor materials and process conditions. Additive manufacturing using a composite of strontium hexaferrite (SrFe12O19) particles and photoresist has been chosen as a method to overcome the difficulties of integrating hexaferrite material to semiconductor substrates. Due to their large internal anisotropy field, the particles of strontium hexaferrite tend to rotate to the field direction instead of changing magnetization direction under application of an external magnetic field (less than the anisotropy field). We have developed a method for 3D printing composites of high strontium hexaferrite concentration (up to 20% by volume) in a liquid photoresist, SU8. Rotation of hexaferrite particles in polymer matrix and thus magnetic anisotropy has been demonstrated in the composite, which is subsequently cured to hold the physical position and orientation of the particles. The anisotropy of the self-biasing field provided by the films has been experimentally characterized, and a ferromagnetic resonance (FMR) frequency ~43 GHz has been observed. We have also characterized the viscosity of the particle-laden polymer at different particle concentrations. 3D printing of this composite with poling will make it possible to directly print magnetic components that require out-of-plane anisotropic magnetization.

Effectively Elevating Ceramic Fillers’ Dispersity in Gel Hybrid Electrolyte through Bridge–Linked Construction for High–Performance Lithium Metal Batteries

Gel polymer-ceramic hybrid electrolytes (GHEs) have emerged as desirable candidates for preparing high energy density and excellent practicability gel batteries. However, the agglomeration of ceramic particles in polymer matrix leads to a decrease in cycling stability and low mechanical properties of GHEs. Here, we present a feasible method for improving the dispersity of Li0.24La0.59TiO3 (LLTO) nanorods in the polyvinylidenefluoride (PVDF)/poly(propylene carbonate) (PPC) co-blended matrix (K–LLTO/PVDF/PPC) by γ-(2,3-epoxypropoxy)propytrimethoxysilane (KH560) surface treatment. The as-prepared GHE with 10% K–LLTO filler (10% GHE) exhibits a high ionic conductivity (3.01 mS cm−1) and an appropriate lithium-ion transference number (0.55). The Li|10% GHE|Li symmetric cell shows an exceptional lithium stripping-plating lifetime of > 2000 h at 0.1 mA cm−2. The assembled LiFePO4 (LFP)|10% GHE|Li full cells show satisfactory cycling stability in the 2.5–4.2 V electrochemical window by recovering 84% of the initial capacity at 2 C over 500 cycles. The uniformly dispersed K–LLTO within the polymer matrix is ascribed to the formation of a bridge-linked network via Si–O–Ti bonds between KH560 and LLTO, and plenty of hydrogen bonds within the polymer matrix. This modification method provides a feasible strategy for fabricating GHEs with good repeatability, which may easily adapt to the high requirements of commercial production.

Poly(Lactic Acid)-Poly(Butylene Succinate)-Sugar Beet Pulp Composites; Part I: Mechanics of Composites with Fine and Coarse Sugar Beet Pulp Particles.

Sugar beet pulp (SBP) is a residue available in large quantities from the sugar industry, and can serve as a cost-effective bio-based and biodegradable filler for fully bio-based compounds based on bio-based polyesters. The heterogeneous cell structure of sugar beet suggests that the processing of SBP can affect the properties of the composite. An “Ultra-Rotor” type air turbulence mill was used to produce SBP particles of different sizes. These particles were processed in a twin-screw extruder with poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) and fillers to granules for possible marketable formulations. Different screw designs, compatibilizers and the use of glycerol as a thermoplasticization agent for SBP were also tested. The spherical, cubic, or ellipsoidal-like shaped particles of SBP are not suitable for usage as a fiber-like reinforcement. In addition, the fineness of ground SBP affects the mechanical properties because (i) a high proportion of polar surfaces leads to poor compatibility, and (ii) due to the inner structure of the particulate matter, the strength of the composite is limited to the cohesive strength of compressed sugar-cell compartments of the SBP. The compatibilization of the polymer–matrix–particle interface can be achieved by using compatibilizers of different types. Scanning electron microscopy (SEM) fracture patterns show that the compatibilization can lead to both well-bonded particles and cohesive fracture patterns in the matrix. Nevertheless, the mechanical properties are limited by the impact and elongation behavior. Therefore, the applications of SBP-based composites must be well considered.

Mikto-Arm Stars as Soft-Patchy Particles: From Building Blocks to Mesoscopic Structures.

We present an atomistic molecular dynamics study of self-assembled mikto-arm stars, which resemble patchy-like particles. By increasing the number of stars in the system, we propose a systematic way of examining the mutual orientation of these fully penetrable patchy-like objects. The individual stars maintain their patchy-like morphology when creating a mesoscopic (macromolecular) self-assembled object of more than three stars. The self-assembly of mikto-arm stars does not lead to a deformation of the stars, and their shape remains spherical. We identified characteristic sub-units in the self-assembled structure, differing by the mutual orientation of the nearest neighbor stars. The current work aims to elucidate the possible arrangements of the realistic, fully penetrable patchy particles in polymer matrix and to serve as a model system for further studies of nanostructured materials or all-polymer nanocomposites using the mikto-arm stars as building blocks.

Feasible management of non-degradable agricultural mulching film wastes into functional flame-retarded materials

A feasible procedure was proposed to convert agriculture mulching film wastes into functional flame-retarded cotton stalk particles-polyethylene-sandy soil composites (CS-PE-SSx) by simple compounding and injection molding. Due to the uniform dispersion of solid particles in polymer matrix and the promising interfacial combination and the potential interacting forces between cotton stalk and sandy soil particles, the resultant composites showed promising mechanical strength (a flexural strength of approximately 29.0 MPa, a tensile strength of approximately 15.8 MPa, and an impact strength of approximately 3.17 kJ/m2) and improved thermal stabilities. The addition of sandy soil particles endowed materials with favorable flame-retarded properties, which can be resistant to fire ignition and flame out within 55 s. Moreover, the actual agriculture wastes containing mulching film residues, cotton stalk, and soil from different areas of China were also successfully transformed into functional composites, which exhibited promising mechanical, thermal, and flame-retarding properties. This study provided a simple, green, and low-cost strategy to convert agriculture mulching film wastes into functional materials, which can be recommended as a viable option to solve the problem of agriculture mulching film wastes.

Microstructure and mechanical properties of oxide particulates reinforced PMCs

Studies are made to utilize the industrial solid waste of ferrochrome (Fe-Cr) slag as reinforcement to make particulate Polymer matrix composites (PMCs). Fe-Cr slag exhibits hard and high strength also consist multiple oxides of SiO₂, Al₂O 3 , MgO, Fe₂O 3 and Cr 2 O 3. Three different sizes (500 µm, 210 µm and 45 µm) were chosen as reinforcement in E glass fiber and epoxy resin matrix. Hand lay-up technique adopted to process all the PMCs. Metallography and mechanical properties evaluation has been done on all these PMCs. SEM studies reveals the homogeneity in the particles distribution and good interfacial bonding between matrix and reinforcements. Improved mechanical properties were observed for all the slag particulates PMCs. However, size of the slag particles also contributing the performance of the composites. Neither coarse (500 μm) nor very fine (45 μm) particles but optimum size of 210 μm slag particles is stimulating to increase the strength of the proposed composites.

Surface Modification of Nano-Hydroxyapatite by Coating Stearic Acid

Todays, researchers are challenging with manufacturing polymeric nanocomposites reinforced with ceramic particles due to two inherent properties of ceramic reinforcement particles, particle agglomeration and incompatibility between hydrophilic ceramic particles and hydrophobic polymeric matrix. So in this study, we used nano-Hydroxyapatite (n-HA) as ceramic material and Stearic acid as amphiphilic material for coating n-HA, hydroxysteric acid (SA) surfactant was used for surface coating particles between the hydrophilic HA powders and the hydrophobic polymers. The surface modification and effect of this method were evaluated by by Fourier transformation infrared (FTIR), x-ray diffractometer (XRD), thermal gravimetric analysis (TGA) and Scanning electron microscopy (SEM). The result of FTIR showed that n-HA surfaces were modified successfully and the modification method had the proper grafting amount according to TGA due to this method of modification will be proper for coating reinforcement particles in polymeric matrix.

Electrically conductive materials for in vitro cardiac microtissue engineering.

Cardiac tissue engineering, a fairly new concept in cardiovascular research, could substantially improve our success in both in vitro modeling of cardiac microtissue and in vivo cardiac regenerative medicine. To a large extent, this success was attributed to mechanical as well as electrical properties of cardiac-designated biomaterials which inherit the fundamental characteristics of a native myocardial extracellular matrix. Large efforts have been made toward designation and construction of these scaffolds which paved the way for more natural-like biomaterials. As an important characteristic, electrical conductivity has grabbed special attention, thus opening up a whole new area of research to achieve the best biomaterial. Electroconductive scaffolds have benefitted from both incorporation of conductive particles in polymeric matrix and fabrication of organic conductive polymers which supported cardiac tissue engineering. However, conductive scaffolds have not yet achieved full success and more work is required to obtain the optimal conductivity with highest similarity to the native heart for in vitro cardiac microtissue engineering.

Synthesis and Characterization of Low Dielectric Polymer Composite: Ethylene-Propylene-Diene Terpolymer/ Barium hexa ferrite

A series of organic- inorganic polymer composites were synthesized by incorporating Barium hexa ferrite (BHF) at different wt % in the Ethylene-propylene-diene terpolymer (EPDM) polymer matrix by adopting solution casting method. The synthesized EPDM/BHF polymer composite were characterized through different techniques i.e.; X-ray diffraction study, SEM(scanning electron microscope), dielectrical and electrical behavior in the frequency range 1 kHz to 1 MHz. A detailed study of the dielectric behavior i.e.; ε’ (dielectric permittivity), tan δ (dielectric loss), M’and M’’ (dielectric modulus) and σac (electrical conductivity) were reported in this communication. The XRD of the composites showed the uniform distribution of the filler particles in the polymer matrix. The SEM micrograph confirms the homogeneous dispersion and distribution of BHF particles in the EPDM polymer matrix. These polymer composite show a promising dielectric behavior which is different from its constituent components.

Erosion behaviour of graphitic carbon nitride (g-C3N4) reinforced epoxy composites

This paper deals with the manufacture and examination of tribological properties of epoxy composites reinforced with graphitic carbon nitride (g-C3N4) nanopowder. The composites had prepared with five different proportions of g-C3N4 nanopowder using a hand layup process. Comparison of tribological properties has made between the composites laid at different percentages of g-C3N4 in epoxy. The results showed the maximum erosion resistance of g-C3N4 particulate polymer matrix for 3% filler content. Also, by Scanning Electron Microscope (SEM), the erosion morphology analysis is done on the internal structures of the specimen.

SRVE modeling of particulate polymer matrix composites with irregularly shaped inclusions: Application to a green stone composite

Particulate polymer matrix composites (PPMCs) play a significant role in a wide range of applications from tissue engineering to aero-structures. Modeling thermoelastic properties of PPMCs can save sizable experimental time and costs, as it provides the capability of predicting the composite’s response to different loading conditions with acceptable accuracies. Micromechanical modeling approach is employed in this investigation to predict the thermoelastic properties of a new particulate polymer matrix composite, made of granite powder as inclusion and the acrylonitrile butadiene styrene (ABS) as matrix—called green stone composite. The reinforcing particles are modeled according to their shape irregularities. Namely, a statistical representative volume element (SRVE) is developed using the concept of integral range, with randomly distributed particles with irregular shapes. Experiments have been conducted to examine the validity of the proposed modeling approach. Numerical and experimental results both show that adding granite powder to pure ABS up to 38% (volume fraction) can notably increase the composite’s thermoelastic properties (bulk and shear moduli as well as thermal conductivity), as high as 200%.

Recent development on modification of synthesized barium titanate (BaTiO3) and polymer/BaTiO3 dielectric composites

In order to fabricate barium titanate (BaTiO3) particles with high purity, small particle size and narrow distribution of particle size, the synthesis methods and doping elements should be properly selected. Compared to polar polymers, non-polar polymers have advantages on the fabrication of miniaturized and lightweight electronic devices, due to excellent process-ability and little endogenous heat generated in the electric field. To avoid the aggregation of BaTiO3 particles in polymer matrix, several nanometer thick organic coating on the BaTiO3 surface is needed. What’s more, the alignment of BaTiO3 and hybrid use of fillers can further improve the dielectric properties of polymer/BaTiO3 composites.

Structural, Dielectric Permittivity and Optical Characteristics of Casting Poly Vinyl Alcohol/Calcium Nickel Aluminate Nanocomposite Films

ABSTRACTTriplex hybrid nanofiller (CaNiAl2O5) have been synthesized by sol-gel method and its nanocomposite (NC) films were incorporated with poly vinyl alcohol (PVA). The scanning electron microscopy (SEM) was used to probe morphological behaviors and dispersion of CaNiAl2O5 in PVA matrix. In order to probe the microstructure X-ray diffraction (XRD) and FTIR were performed on PVA/CaNiAl2O5 NCs. Based on the results of both XRD and transmission electron microscopy (TEM), the average particle size of the CaNiAl2O5 lies in the range 7–15 nm. The current (I) – voltage (V) behaviors were studied using LCR-meter at room temperature. The dc-conductivity increases with increasing in both CaNiAl2O5 at different voltages. The dielectric constant exhibits higher values at lower frequency and increases with nanoparticle (NP) loading due to increase in polarization particles in polymer matrix. The ac conductivity tends to increase with increase frequency and NPs content. The cyclic voltammetric data indicate the NC with 8wt% NPs exhibit higher specific capacitance as compared with PVA. The optical constants of the NCs were evaluated from UV-Visible spectra. The band gap energies has a blue shift from 4.4 eV (PVA) to 2.8 eV (PVA/8wt% CaNiAl2O5), whereas refractive index (RI) and the optical conductivity of NCs increased with an increasing in NPs content.

Efficiency of dental caries prevention with the use of polymer-based toothpastes modified by the electromagnetic field.

The most important problems of modern dentistry cover not only the early diagnosis but also prevention of dental caries, including the one based on the use of various hygienic products and therapeutic agents. Normally, the processes of re- and demineralization in the oral cavity are in a state of dynamic. However, in the presence of cariogenic factors, the balance is shifted towards demineralization. In the event of initial caries, enamel remineralization is possible only to a certain extent, and specifically, for a reversible degree of carious lesion. There was an idea about structural changes in polymer-based consumable dental materials including toothpastes. The purpose of the study is to increase the efficiency of dental caries prevention based on the activation of metabolic processes in dental hard tissues with the use of R.O.C.S. Active Calcium toothpastes (Russian-Swiss "DRC-Group" company) modified by an electromagnetic field. As a result of the experimental part of the study, certain changes in the properties of the R.O.C.S. Active Calcium toothpastes under the electromagnetic field influence including microstructural transformation of the toothpaste (an increase in the size of the polymer matrix particles and a decrease in the distance between them confirmed by the electron microscopy findings), confirmed by the transmission electron microscopy results. The investigations with the help of X-ray microanalysis made it possible to clarify the chemical composition of the surface layer of the tooth enamel, for the first time to reveal in detail the concentration of micro- and macroelements of organic and inorganic nature, to trace the changes occurring under controlled tooth cleaning with the R.O.C.S. Active Calcium toothpaste treated with an electromagnetic field. The obtained results promote the further studies of laws in change of physical and mechanical properties of treatment-and-prophylactic means under the electromagnetic field influence in respect of dental caries preventive maintenance efficiency increase.

The mechanism for the temperature-dependency of the interfacial interaction in polyamide/tin-fluoro-phosphate glass composites

The interfacial interaction in polyamide/tin-fluoro-phosphate glass (TFP-glass) composites exhibits a positive correlation with temperature, whose mechanism is still unknown. The thermal-induced dissociation behavior at 232 °C of TFP-glass, which has been observed and investigated in our previous works, provides a plausible mechanism for the temperature-dependency of the interfacial interaction. In this work, the influence of the dissociation degree, which is controlled by processing temperature, on the interfacial interaction between TFP-glass and copolymerized 6/66 copolymer (cPA) is investigated. Three processing temperatures, 215, 230, and 245 °C (below, around and above the dissociation temperature of TFP-glass, Td = 232 °C), are chosen to prepare cPA/TFP-glass composites. With increasing the degree of dissociation, improved dispersion of TFP-glass particles in polymer matrix and enhanced interconnection between the two components are observed, indicating that the interfacial interaction in cPA/TFP-glass composites is gradually enhanced. The dielectric relaxation spectra, which can probe the local motions of macromolecular fragments at different length scales, are used to investigate the influence of the dissociation degree on the length scale of the interfacial interaction in cPA/TFP-glass composites. The improved thermal stability of cPA/TFP-glass composites filled with the same content of TFP-glass also confirms the enhancement of the interfacial interaction. Therefore, conclusions can be drawn that the dissociation behavior of TFP-glass is contributed to the temperature-dependency of the interfacial interaction in polyamide/TFP-glass composites. The work reported in this paper should provide theoretical guidance for taking advantage of this positive correlation with temperature of the interfacial interaction and help us to deeply understand the mechanism for the interfacial interaction in TFP-glass filled composites.

Effect of Pistachio Shell Particle Content on the Mechanical Properties of Polymer Composite

The effect of the content of microscale natural pistachio shell particles on the mechanical properties of polyester matrix composites was experimentally investigated. The pistachio shell particle contents were 0, 5, 10, 15, 20, and 25 wt%. Tensile, flexural, and Charpy impact tests were carried out on molded composite specimens according to the ISO 179/92 standard. Good dispersion of pistachio shell particles in polymer matrix was observed using SEM micrographs. The highest tensile strength, flexural strength, and impact strength were obtained at a pistachio shell particle content of 10, 5, and 5 wt%, respectively.

Eletroless Silver Coated Nanocenosphere/Polymer Composite for EMI Shielding Effectiveness

Electromagnetic interference (EMI) is an escalating concern in the modern electronic climate. As such it has become a critical area to consider when designing and packaging electronics. In this context, Electroless Silver Coated nanocenosphere (SCNC) in Poly Methyl Methacrylate (PMMA) and Acrylonitrile Butadiene Styrene (ABS) composites has been tried for its EMI shielding effectiveness. The strategy is to render the polymer conductive by dispersing SCNC in various proportions in these polymers separately and to promote wave absorption by making sheet of the polymer-based composite. In our study EDX (Energy Dispersive X-Ray) analysis confirmed the presence of Ag on the coated nano cenosphere. This was further, confirmed through Phase analysis by XRD (X-Ray Diffractometer) analysis. SEM (Scanning Electron Microscope) analysis was conducted to see the size, shape and adherence of the Ag coating on nanoenosphere particles and to observe the distribution of these particles in polymer matrix in the composite sheet. BET Surface area of electroless coated powders was quite high indicating good surface properties. The processing methods, electrical properties (surface resistivity) and electromagnetic behavior (EMI shielding effectiveness) were investigated. Shielding effectiveness (SE) values of approximately 25 dB at a frequency of 1 GHz was obtained for coatings of Electroless Silver coated nanocenospheres in ABS polymer which was further increased by adding other conductive nano fillers (Graphene and multi walled Carbon Nano tube) along with coated nanocenospheres.

Analytical and numerical modeling on resonant response of particles in polymer matrix under blast wave

A novel methodology is proposed in this paper to design polymer matrix with particles for protecting against the blast wave. Through the adoption of vibration analysis, two kinds of basic equivalent unit cell models introducing the massive springs are developed and the corresponding relations for structural parameters considering the Poisson effects are derived. The resonant frequencies of particles are obtained by theoretical prediction and compared with the results of finite element analysis, in which a good agreement is achieved. Based on the theoretical analysis, two types of composite materials with different geometry configurations are proposed and the 3D periodic models are established to investigate the dynamic performance under blast wave. The energy history of system is calculated to study the energy transfer effect among components. Additionally, the numerical parametric studies are conducted to investigate the effects of coating properties and particle volume fraction on the wave propagating in these two unit cell models. The acquired results show that the attenuation of blast wave is caused by the interaction between the elastic wave motion and the resonant particles. The coating properties and particle volume fraction are significant factors to affect the wave propagation and attenuation. The dominant frequencies of spectrum obtained by the simulations are well coincident with the theoretical solutions.

Effect of Polymer Architecture on the Structure and Interactions of Polymer Grafted Particles: Theory and Simulations

We use Langevin dynamics simulations and Polymer Reference Interaction Site Model (PRISM) theory to study polymer grafted nanoparticles specifically to explain the impact of comb polymer architecture on the grafted layer structure and effective interparticle interactions in solvent and in matrix polymer. First, we use simulations to study a single particle grafted with comb polymers with varying comb polymer design (i.e., spacing and length of side chains along the comb polymer backbone), grafting density (i.e., polymer chains/particle surface area), and particle curvature in implicit solvent at the athermal limit. We find that increasing side chain length or decreasing side chain spacing along the comb polymer effectively swells and extends the polymer backbone due to the increasing side chain monomer crowding. For particles at finite curvature with increasing side chain monomer crowding, the monomer concentration profile of the comb polymer backbone at short distances from the surface resembles the concentration profile of a semiflexible linear polymer and at farther distances resembles that of flexible linear polymers grafted to a flat surface. As the particle curvature decreases to zero (i.e., flat surface), increasing side chain crowding has a simpler effect of expanding the grafted layer without changing the overall shape of the concentration profile. To understand how architecture affects the interactions of the comb polymer grafted particles, we use PRISM theory to calculate the potential of mean force (PMF) between comb polymer grafted particles in implicit solvent, explicit solvent, and explicit matrix of athermal linear polymers. On the basis of the PMFs calculated for a wide range of design parameters (grafting density, comb polymer design), we find that, compared to linear polymers, the comb polymers exhibit stronger effective attraction in the PMF between the grafted particles in both small molecule solvent and polymer matrix due to the increased crowding in the grafted layer from the comb polymer side chains. Interestingly, the PMF between the grafted particles in a small molecule solvent is more sensitive to the comb polymer design (i.e., side chain length and spacing) than the PMF between the grafted particles in a polymer matrix.

Effects of Organo-Modified Clay Addition and Temperature on the Water Vapor Barrier Properties of Polyhydroxy Butyrate Homo and Copolymer Nanocomposite Films for Packaging Applications

Polymer nanocomposites, based on bacterial biodegradable thermoplastic polyester, poly(hydroxy-butyrate) (PHB), poly(hydroxyl-butyrate-co-hydroxy-valerate) (PHBHV), and commercial organo-modified montmorillonite (OMMT-Cloisite 10A) were prepared by solution casting method. This work aims to investigate the effect of Cloisite 10A type clay addition on the water vapour permeability properties of PHB/OMMT, and PHBHV/OMMT nanobiocomposite films. Temperature dependence of water vapor permeabilities of the films were also evaluated at various temperatures, and semi empirical permeability models were used to predict the permeability of polymer systems as a function of clay concentration and aspect ratio of nanoplates. Moreover, thermal, optical, and mechanical properties of the composites were examined by using varieties of techniques including differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), scanning electron microscope (SEM), and thin-film X-ray diffractometer (TF-XRD) respectively. Test results indicated that addition of highly intergallery swollen Cloisite 10A to the PHB/PHBHV, reduced the water vapor permeability up to 41 and 25% compared to native PHB and PHBHV films, respectively. Regarding the all mechanical properties measured, the maximum improvement was achieved for 3 wt% clay loaded samples for both PHB and PHBHV polymer composites. An increase of about 152 and 73% in tensile strength and of 77 and 18% in strain at break was achieved for PHB and PHBHV polymers, respectively. As a result of X-ray diffraction analysis, exfoliated structure was achieved at low clay loaded sample (1% w/w), however at higher concentration (3% w/w) the structure found as intercalated. Therefore, it is an evident that enhancement of characteristic properties highly depend on the dispersion level of clay particles in polymer matrix. The results obtained in this study show the feasibility of improvement of the properties of PHB based polymers with incorporation of nanoclay.