Polystyrene Composites Research Articles

Upcycling by grafting onto semi‐crystalline polymers using supercritical CO2

AbstractThe creation of graft copolymers by selectively grafting a second polymer to the amorphous fraction of a semi‐crystalline polymer in supercritical CO2 is demonstrated herein. The graft copolymer is synthesized by free radical polymerization of a vinyl monomer within the semi‐crystalline polymer below its melt temperature. Such conditions afford selective grafting on the amorphous regions (block “B”) while leaving the crystalline domains (block “A”) unmodified. Accordingly, unique A‐B, A‐B‐A, A‐B‐A‐B‐A, and so forth. block structures are formed. In this work, styrene is polymerized within polyamide 6, polyethylene terephthalate, and isotactic polypropylene. Purification of these material is performed to remove the un‐grafted homopolymer, allowing for determination of the graft yield, the portion of polymer which covalently bonds to the semi‐crystalline matrix. Grafting yields achieved in polyamide 6, polyethylene terephthalate, and isotactic polypropylene were 98%, 59%, and 15%, respectively. Property enhancements were observed upon further characterization of polystyrene‐polyamide 6 copolymers, including high glass transition temperatures, the ability to be remelted, and tunable grafting molecular weight. Additionally, hydrophobicity is controlled by varying polystyrene composition. The remarkable range of accessed properties demonstrates this as a potential route to upcycling plastics.

Cell growth, deformation and model establishment of micro-foamed polystyrene material

Abstract The paper uses chemical foaming method to prepare foamed polystyrene (PS) composites by a self-made visualization system. During the cell growth and deformation process, the radial response area model, the hoop tension model and cell deformation model of the resin around were established at the molecular scale, and the cell growth and deformation process of the actual injection molded and visualized expanded polystyrene (PS) composites were simulated and verified. The results show that we have established the radial response area model, the hoop tension model and cell deformation model of the surrounding resin, and the actual injection foaming process is basically consistent with the visualized simulation results of light microscope. In different foaming stages, the radial migration and circumferential stretching of the surrounding resin by the cells are different, which ultimately leads to different deformation of the cells. The growth and deformation of the cells have verified the feasibility of the radial response area model, the hoop tension model and cell deformation model during foaming process. This research work is of great significance to guide the foaming of polyolefin materials.

Space Charge Behavior of Quantum Dot-Doped Polystyrene Polymers

This paper deals with the role played by the interface and bulk volume of the nanofiller about affecting the electrical properties of a nanocomposite material. For this purpose, a simple and completely amorphous matrix, polystyrene (PS), is used as base material, and core-shell quantum dots are exploited for simulating the structure of nanocomposites: CdSe core and CdSe-ZnS core-shell semiconductor quantum dots (QDs) are added into a PS matrix. The latter is to highlight the effect of the ZnS interface and as contrast to the core material. Dispersion and distribution of QDs are first microscopically observed and optimized by including isopropyl alcohol in the manufacturing phase as an additional solvent. Among electrical properties the focus is on space charge accumulation, tested by means of the pulsed electroacoustic technique at 10 kV/mm and 50 kV/mm on CdSe and CdSe-ZnS doped PS composites. Results are then compared with a reference PS without QDs. Trap depth and density are also obtained by space charge measurement results. When CdSe QDs are added to PS, the trap density increases with respect to the baseline values measured on the unfilled polymer. In contrast, the ZnS shell around the CdSe core creates an additional trap level with lower trap depth, which increases charge mobility, thus turning homocharge into heterocharge accumulation. Therefore, the surface shell-structure of QD nanocrystals appears to significantly influence the space charge behavior of the nanocomposite, independently of the polymer.

Electrical transport phenomenon and variable range hopping conduction in reduced graphene oxide/polystyrene composites

In this work, we investigate the temperature dependence of the electrical conductivity of a reduced graphene oxide (RGO)/polystyrene (PS) composites. We re-analysed, in our investigation, the experimental measurements of RGO/PS composites with different RGO concentrations obtained by W. Park et al. We show using two different methods: the Zabrodskii method and a numerical method based on the calculation of the percentage deviation; that the electrical conductivity follows, at the beginning, the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T−1/2 . This behavior showed that long range electron-electron interaction reduces the Density Of State of carriers (DOS) at the Fermi level and creates the Coulomb gap (CG). When the RGO concentration increases, we noticed that the temperature dependence of the electrical conductivity tends toward T−1/3 , which may suggest a possible crossover from ES VRH regime to the Mott VRH regime for high RGO concentration values. We also, calculated and represented the Density Of State (DOS) per energy and per area function for each sample. We noted that the width of parameter representing the half of CG width decreases by increasing the RGO concentration and the function tends toward the constant corresponding to the Mott VRH

Accelerated photodegradation of polystyrene by TiO2-polyaniline photocatalyst under UV radiation

Photodegradation of polystyrene (PS) was studied under ultraviolet (UV) radiation, using nano TiO2, surface modified with polyaniline (PANI). X-Ray diffractogram reveals that the crystalline structure of TiO2 remained intact in TiO2-PANI composites. The existence of strong molecular interaction between TiO2 and PANI lead to a decrease in the optical bang gap energy of TiO2 in the composites. PS loaded with TiO2-PANI composites underwent better chain scission and photo-oxidation compared to PS and PS-TiO2 composites, upon UV irradiation. TiO2-PANI composites enhanced the mechanical properties (tensile and flexural) of PS appreciably. Tensile and flexural strengths however decreased with respect to UV exposure time, proving mechanical deterioration of the polymer composites as an outcome of photodegradation. Thermal stability of the composites too decreased upon UV exposure. A decrease in the values of break down voltage as well as increase in dielectric permittivity of the composites upon UV irradiation suggests the formation of charge centers and polarisable species in the polymer matrix. All the polymer composites underwent considerable weight loss due to the formation and evolution of volatile gases, during the course of photodegradation. Suitable mechanism of degradation of PS composites was proposed based on the observed results.

Preparation and properties of polystyrene composites modified by macromolecule flame retardant DOPO-HQ

A macromolecular flame retardant was firstly the group reaction of DOPO-HQ. The modified polystyrene ADOPO-HQ-co-PS was prepared by copolymerization of macromolecular flame retardant and styrene. Its chemical structure was analyzed by Fourier transform infrared (FT-IR). PS composite was prepared by adding it to the experimental formula, and the cone-shaped calorimetry experiment was carried out on the material. The results show that it has a better flame retardant performance than DOPO-HQ. The smoke generation rate is very small, the highest is 0.2m 2/s, the CO production is very small, the highest is 0.007g/s, and the mass loss is the highest is 0.14g/s, which shows that the material is more environmentally friendly and stable during combustion.

Acoustic, ultrasonic, mechanical properties and biodegradability of sawdust/ recycled expanded polystyrene eco-friendly composites

In the present study, sawdust/recycled expanded polystyrene (SD/rEPS) composite was manufactured to be used as sound-absorbing materials. To achieve this aim, SD/rEPS composites containing different loading level (0, 20, 40, 60 and 80 wt percent) of SD were prepared. The addition of 20% SD exhibited better dispersion within recycled expanded polystyrene (rEPS) matrix than higher loading level of SD, as indicated from scanning electron microscope. Consequently, the tensile strength and flexural strength were improved by 16.7% and 14.1%, respectively. The higher loading level of SD displayed aggregation within rEPS matrix which reflected negatively on the mechanical properties. Young's and shear modulus varied from between 0.41 and 1.23 GPa for 0–60% SD. Longitudinal and bulk modulus recorded a reduction from 0.55 to 1.26 GPa with increasing SD. Sound absorption improved with increasing SD loading level. Nonperforated samples of 60% SD and 80% SD had high absorption at 500 and 315 Hz where the sound absorption coefficient (SAC) was about 0.85 and 0.75, respectively. The perforated sample of 80% SD exhibited the highest sound absorbing at low frequencies 315 Hz (SAC~0.9). The biodegradability of the prepared composites was investigated using burial in soil for 90 days where the weight loss increased linearly with increasing SD within the rEPS matrix.

Effect of Silane Coupling Agent on Flexural Strength and Hardness of Wheat Straw Polystyrene Composites

In the present research work, the effect of silane treatment along with alkali treatment on flexural strength, flexural modulus, and hardness investigated. Wheat straw as a filler was added (5%, 10%, 15% and 20%) to polystyrene matrix to prepare wheat straw polystyrene composite. The wheat straw fibre was first treated with 20% NaOH and 1% silane coupling agent to prepare wheat straw polystyrene composite. The compounding process was carried out in twin-screw extruder and samples were prepared by the compression moulding process. There was an increase in flexural modulus (214%), flexural strength (44%), and hardness (28%) of composite with the addition of alkali and silane treated wheat straw fibre.

Multifunctional Oil Absorption with Macroporous Polystyrene Fibers Incorporating Silver-Doped ZnO

Hydrophobic microporous polystyrene (PS) fibers are fabricated by a solvent-induced phase-separation-assisted electrospinning method. Zinc oxide (ZnO) and silver-doped zinc oxide (Ag-ZnO) nanomaterials with variable morphologies are added to the PS fibers, to investigate the influence of multifunctional nanofiller addition on the porosity and consequent oil-adsorbing properties for different oil types. The doping of silver as well as the uniformity in particle distribution are confirmed by scanning electron microscopy and the energy-dispersive spectral analyses. The porosity of the fibers and their crystallinity effect depend on the hydrophobicity and surface properties of these microporous nanofilled fibers. Ag-ZnO, specifically in 2 wt %, enhanced the pore size and distribution in PS porous fibers, thereby enhancing the oil-adsorbing property and its hydrophobicity. In-depth analysis of the oil adsorption mechanism is done for the fibers, both qualitatively and quantitatively, to demonstrate its correlation with the structural integrity of the fibers. The PS/2Ag-ZnO composite also exhibits the highest antibacterial performance against Staphylococcus aureus, a general indication of antibiological fouling properties of these oil-separating films. The antifouling/antibacterial activity of the nanoparticles and high oil sorption capacity of the highly porous PS composites show great potential for use in water-treatment-related applications.

Synergistic Effects of Graphene and Ammonium Polyphosphate Modified with Vinyltrimethoxysilane on the Properties of High-Impact Polystyrene Composites.

Ammonium polyphosphate (APP) was modified with a silane coupling agent (vinyltrimethoxysilane, Si-171), and then the synergistic flame retarding effect of graphene and surface-modified APP (APP@Si-171) on high-impact polystyrene (HIPS) was investigated. Surface modification and thermal stability characterization of APP were analyzed by Fourier transform infrared spectroscopy (FTIR), energy dispersive spectrometer (EDS), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that surface-modified APP (APP@Si-171) exhibited significantly better dispersion and less agglomeration tendencies compared with pure APP. A series of target HIPS composites containing different mass fractions of the two flame retardants were prepared by melt blending. TGA and cone calorimeter tests (CCT) were conducted to quantitatively investigate the thermal and flammability properties of the composites, respectively. Results from TGA and CCT demonstrated that the addition of the flame retardants delayed the onset and peak temperatures in differential thermogravimetry (DTG) curves and weakened the peak heat release rate (PHRR) and total heat release (THR). Moreover, the synergistic effect index (SE) was employed to quantify the synergistic behavior between the two fillers, and the results showed that APP@Si-171 and graphene had a synergistic effect on improving the thermal stability and flame retardancy of HIPS.

Blend Morphology in Polythiophene–Polystyrene Composites from Neutron and X-ray Scattering

In this work, contrast-variation small-angle and ultra-small-angle neutron scattering are used together with wide-angle X-ray scattering (WAXS) to characterize the bulk molecular conformation and s...

WITHDRAWN: Characterization for Polymer Composites of Lead Iodide and Polystyrene as Room Temperature X-rays Detectors

Abstract Here in this paper, the polymer composites of lead iodide with polystyrene is characterized and compared on the basis of parameters e.g. IMAX/IMIN, energy band gap and product of mobility with lifetime. The three compositions of lead iodide and polystyrene are compared for room temperature X-ray detector on the different parameters. The value of IMAX/IMIN, energy band gap and mobility lifetime product are calculated for all three compositions and the trends of changing of these parameters are discussed. The change in trends of these parameters suggests a positive direction and may be there some tradeoff. This paper directs a way to work on polymer composites in comparison of earlier radiation detectors.

Investigation of Carbon Nanotube Grafted Graphene Oxide Hybrid Aerogel for Polystyrene Composites with Reinforced Mechanical Performance.

The rational design of carbon nanomaterials-reinforced polymer matrix composites based on the excellent properties of three-dimensional porous materials still remains a significant challenge. Herein, a novel approach is developed for preparing large-scale 3D carbon nanotubes (CNTs) and graphene oxide (GO) aerogel (GO-CNTA) by direct grafting of CNTs onto GO. Following this, styrene was backfilled into the prepared aerogel and polymerized in situ to form GO–CNTA/polystyrene (PS) nanocomposites. The results of X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy indicate the successful establishment of CNTs and GO-CNT and the excellent mechanical properties of the 3D frameworks using GO-CNT aerogel. The nanocomposite fabricated with around 1.0 wt% GO-CNT aerogel displayed excellent thermal conductivity of 0.127 W/m∙K and its mechanical properties were significantly enhanced compared with pristine PS, with its tensile, flexural, and compressive strengths increased by 9.01%, 46.8%, and 59.8%, respectively. This facile preparation method provides a new route for facilitating their large-scale production.

Butyltriphenylphosphine‐based chelate borates influenced on flame retardancy of polystyrene composite containing self‐expanded intumescent flame retardants

AbstractThe polystyrene (PS) composite containing self‐expanded intumescent flame retardant (polyphosphate ammonium and expandable graphite) was blended with three butyltriphenylphosphine‐based chelate borates, respectively, to evaluate their effect on flame retardancy. The chemical structure of as‐prepared three chelate borates was confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectrum (FTIR). The flame retardancy of various PS composites was evaluated by vertical burning test (UL‐94), limited oxygen index (LOI), and cone calorimeter (CC). Flammability and combustion results suggested that one of chelate borates, named [BTP][BMB], made PS composite (PS4) obtain V‐0 rating, 27.0 ± 0.3% LOI value, and reduction on heat release and smoke production with 17 wt% total flame retardants loading. The combustion residue was analyzed by scanning electron microscope and FTIR, and the pyrolysis gaseous products were investigated by TG‐FTIR technique. Besides, complex viscosity of PS composites composed of various chelate borates from a rheology instrument indicated that the improvements of flame retardancy of PS composites depended on the temperature of construction of crosslinked network by expandable graphite, which the chelate borates showed distinctive influence. Accordingly, the flame‐retarding mechanism about fast response to flame has been proposed.

Thermomechanical Multifunctionality in 3D-Printed Polystyrene-Boron Nitride Nanotubes (BNNT) Composites

In this work, polystyrene (PS) and boron nitrides nanotubes (BNNT) composites were fabricated, prepared, and characterized using modified direct mixing and sonication processes. The polymer composites were extruded into filaments (BNNTs at 10 wt. %) for 3D printing, utilizing the fused deposition modeling (FDM) technique to fabricate parts for mechanical and thermal applications. Using a direct mixing process, we found that the thermal conductivity and the mechanical strength of the PS-BNNT composite were respectively four times and two times higher compared to the sonication method. The thermal stability and glass transition temperatures were positively affected. A 2D microstructural mechanical entanglement model captured the exact geometry of the nanotubes using the MultiMechanics software, and the performance of the additive manufactured (AM) PS-BNNT composites part for thermomechanical application was simulated in COMSOL. The modified direct mixing process for PS-BNNT, which affects morphology, proved to be effective in achieving better interfacial bonding, indicating that BNNTs are promising fillers for improving thermal and mechanical properties, and are applicable for thermal management and electronic packaging.

Anisotropic Magnetism in Gradient Porous Carbon Composite Aerogels

Porosity is of high importance for functional materials, as it allows for high surface areas and the accessibility of materials. While the fundamental interplay between different pore sizes and functionalities is quite well understood, few studies on gradually changing properties in a material exist. To date, only a few examples of such materials have been synthesized successfully. Herein, we present a facile method for synthesizing macroscopic carbon aerogels with locally changing pore sizes and functionalities. We used ultracentrifugation to fractionate differently functionalized and sized polystyrene nanoparticles. The assembly into gradient templates was conducted in a resorcinol–formaldehyde (RF) sol, which acted as a liquid phase and carbon precursor. We show that the modification of nanoparticles and a sol–gel precursor is a powerful tool for introducing dopants (sulfur and phosphorous) and metal nanoparticles (e.g., Ni) into gradient porous carbons formed during the carbonization of the RF sol. Understanding the underlying interactions between particles and precursors will lead to a plethora of possibilities in the material design of complex functionally graded materials. We showed this by exchanging parts of the template with magnetite–polystyrene composites as templating nanoparticles. This led to the incorporation of magnetite nanoparticles in the formed gradient porous carbon aerogels. Finally, gradually increasing concentrations of magnetite were obtained, ultimately leading to macroscopic carbon aerogels with locally changing magnetic properties, while the graded porosity was maintained.

Water Absorption, Thermal and Microstructural Properties of Plastic Composites Developed from Isoberlinia Doka Wood Sawdust and Polystyrene Wastes

In this study, the water absorption, thermal conductivity and microstructural properties of Isoberlinia doka wood sawdust polystyrene composite, synthesised by the hand layup method, were investigated as a function of filler content. It was observed that the thermal conductivity increased with increase in the fibre loading. The thermal conductivity value obtained for the synthesised composite samples was an average of 0.147 Wm−1 k−1. The composites absorbed water until equilibrium was achieved on the 9th day. The maximum water absorbed at equilibrium for the composite with filler concentration of 10, 20, 30 and 40 wt% was 36.46, 40.34, 57.53, 128.65 wt%, respectively. The mass transfer kinetics revealed that water sorption rate increased at higher filler composition due to the increased interstitial pores and gaps that are exacerbated by increased fibre loading. The mass transfer kinetic constants for the composite with filler concentration of 10, 20, 30 and 40 wt% were 0.738, 0.661, 0.996 and 1.155 day−1. Microstructural analysis revealed that the dispersion of wood sawdust particles improved as the fibre loading increased.

Artificial Neural Network Modeling of the Water Absorption Behavior of Plantain Peel and Bamboo Fibers Reinforced Polystyrene Composites

The research described here aimed to model the water absorption behavior of reinforced polystyrene (PS) composites developed from powders of plantain peel (PPC) and bamboo fiber (BFC) using the Artificial Neural Network (ANN) model. The composites were developed by manual mixing and hand layup at room temperature (25 ± 2 °C) and cured by open molding at room temperature for 7 days. Water absorption tests were performed according to the ASTM standard method (D1037-99, ASTM, 1999). The water absorption was observed to increase with both filler loading and immersion time for both PPC and BFC. The coefficient of determination (R 2) values >0.98 were achieved for training, validation, and testing for both composite types. The model results showed low root mean squared error values (<1 wt%), revealing that in the utilization of the model a high accuracy threshold was expected for the ANN predictions. Parity plots revealed that the models gave a good balance between over-predictions and under-predictions and the accuracy could be substantiated both at low and high water absorption prediction values. ANOVA revealed that the results were statistically significant at a significance level of p < 0.05.

Mechanical and thermal properties of polystyrene and medium density fiberboard composites

Virgin polystyrene (PS) composites were reinforced with medium density fiberboard (MDF) residue, considering the influence of fiber content. The composites were evaluated for their morphology, identification of functional groups and thermal behavior. Mechanical tests and a degradation study under ultraviolet radiation (UV) were also performed. The results showed that the best properties were obtained for composites with 4% by mass of MDF waste. The addition of residue was found to increase thermal stability of polystyrene compared to its pure form. The morphology of the composites showed homogeneity of the material. In the degradation tests under ultraviolet (UV) radiation, it was found that the presence of MDF residue slows down the matrix degradation process when evaluated by means of tensile strength. Polystyrene composites reinforced with MDF residues showed good mechanical properties and can be applied in the development of materials that do not need a good appearance.

Evaluation of the Electrical Characteristics of Recycled Iron Reinforced Polystyrene Composites

The prospective reuse of iron fillings from the milling machine and polystyrene in the solid waste streams in the production of plastic composites were considered in this study. The preparation, electrical properties, density, void fraction and particle distributions of the solvated polystyrene filled composites were all investigated as a function of recycled iron fillings concentration. The composites were developed by hand layup technique and cured by casting under ambient conditions (25 ± 2oC) for 7 days. The compared micrographs confirmed well-dispersed recycled iron fillings in polystyrene matrix and decreasing void fraction as iron filling increases in the composites. The highest electrical conductivity and density values of the composites were obtained at the highest iron filling composition of 40 wt% as 5.91 × 10-07 S/cm and 1.31 g/cm3, respectively. The developed iron polystyrene composite has good electrical properties, making it suitable to be an alternative material for metals.