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Poly(vinylidene fluoride) (PVDF) was electrospun into ultrafine fibrous membranes from its solutions in a mixture of N,N-dimethylformamide and acetone (9:1, v/v). The electrospun membranes were subsequently treated by continuous hot-press at elevated temperatures up to 155°C. Changes of morphology, crystallinity, porosity, liquid absorption, and mechanical properties of the membranes after hot-press were investigated. Results of scanning electron microscopy showed that there were no significant changes in fibrous membrane morphology when the hot-press temperature varied from room temperature to 130°C, but larger pores were formed because of fibers melting and bonding under higher temperatures. Analyses of X-ray diffraction and differential scanning calorimeter exhibited that the crystalline form of PVDF could transfer from β-type to α-type during hot-press at temperatures higher than 65°C. Tensile tests suggested that the mechanical properties of the electrospun PVDF membranes were remarkably enhanced from 25 to 130°C, whereas the porosity and the liquid absorption decreased. The hot-press at 130°C was optimal for the electrospun PVDF membranes. The continuous hot-press post-treatment could be a feasible method to produce electrospun membranes, not limited to PVDF, with suitable mechanical properties as well as good porosity and liquid absorption for their applications in high-quality filtrations or battery separators. POLYM. ENG. SCI., 48:934-940, 2008. © 2008 Society of Plastics Engineers, INTRODUCTION The electrospinning is a straightforward way to produce ultrafine fibrous membranes from polymer solutions or melts under a high electric voltage [1-5]. Because of the tiny diameter in several [...]

Polymeric nanocell foam is a promising material that faces manufacturing challenges. Producing sizable and thick foams for properties testing has been challenging. This study aims to scale up and understand the foaming mechanism of nanocellular foams by controlling the saturation temperature, pressure, and molecular weight distribution of the matrix to fine-tune the glass transition temperature of the polymer/gas mixture. The hot-press foamed samples possess a 100 x 70 x 6 ~ 8 [mm.sup.3] dimension and a cell size of less than 200 nm. Bimodal structures can also be created by controlling the critical processing parameters. Introducing 37% microcells into unimodal nanocellular foam reduced the relative density from 0.29 to 0.19. The thermal conductivity of the foams was tuned by controlling the cell size distribution. Unimodal nanofoams have the lowest thermal conductivity for foams of the same density due to the Knudsen effect and tortuosity. The measured thermal conductivity is in agreement with theoretical models. Highlights * PMMA nanofoam with a dimension of 100 x 70 x 6-8 [mm.sup.3] and cell size below 200 nm. * The morphology of nanofoams was tuned to be unimodal and bimodal. * The foam density of the bimodal nanofoams was lowered below 0.238 g/[cm.sup.3]. * The thermal conductivity of foams was tuned by controlling the cell structure. KEYWORDS bimodal, hot-press, nanocellular foam, PMMA, thermal conductivity, 1 | INTRODUCTION The demand for energy has significantly increased due to the population growth. The building sector accounts for over one-third of global energy consumption and carbon dioxide emissions. [...]

In-mold decoration is an integrated process for plastic processes, such as printing, hot pressing, and injection molding. The process has simpler steps, the production time is shorter, products are more durable, and manufacturing costs are less than traditional methods. In-mold decoration is affected by shape, mold design and the parameters for forming, and cracking, wrinkling or stress concentration can occur. A large curvature can produce cracks and wrinkles. This study designs a series of experimental methods for film forming, hot press forming, and injection molding. The effects of various features on the quality of the hot press forming and injection molding processes are determined. A three-dimensional film forming process uses pressure thermoforming technology to form either without pretensioning, with pretensioning, and with local heating. The local heating method gives the best results. For injection molding processes, the mold temperature, the melt temperature, the injection speed, and the holding pressure are the parameters. The injection molding process is optimized using the Taguchi method, and the factor with the highest contribution is determined to be the holding pressure. The conductive line of the finished in-mold decoration product can be formed smoothly by hot pressing using local heating, and the measured resistors are almost the same after each process. KEYWORDS in-mold decoration, injection molding, printed circuit, thermoforming, 1 | INTRODUCTION Electronic devices are becoming more complex and functional, but miniaturization is required to ensure portability. Many consumer electronics, home appliances, LOGO nameplates, and automotive parts are produced [...]

To improve the surface bonding strength of polypropylene (PP) decorative films on wood-based panels, one kind of lignin, namely sodium lignosulfonate (SL) filled waterborne polyurethane (WPU) composites were used as adhesives on the back of the PP decorative films, and the SL was modified by the addition of two alternative types of silane that contain either ethylene-acyloxy or epoxy groups. The PP decorative films were hot-press onto plywood using the different types of SL modified WPU as an adhesive. The SL and SL modified WPU were characterized comprehensively. The surface properties the PP decorative films on plywood surfaces were tested. The results showed that both types of silane can be grafted on the SL between hydrolyzed Si--OH groups and -OH groups. The long organic chain of silane can physically twist to the WPU, where self-polymerization of the silane helps to form network structures. As a result, the surface bonding strength of PP decorative films on plywood surfaces largely improved with SL filled WPU adhesives and no detachment occurred in boiling water. Compared with the ethylene-acyloxy silane, the epoxy silane performed better which was associated with the reactions between the epoxy groups and free water. KEYWORDS plywood, polypropylene decorative film, sodium lignosulfonate, surface bonding strength, waterborne polyurethane composites, 1 | INTRODUCTION Polyolefin decorative films produced from polyvinyl chloride (PVC) or polypropylene (PP) materials are important surface finishing products that are widely used in wood-based products such as wooden [...]

The present study focuses on utilizing polystyrene emulsion treated newsprint microcrystalline fibers (NPMCF). These treated fibers were then added to styrene-butadiene rubber (SBR) at different concentrations, namely, 3, 6, 9, and 12 phr (part per hundred part of rubber). Mixing of ingredients was carried out on a rubber roll mill and afterward molded as a thin film on a hot press, then, exposed to electron beam irradiation doses up to 200 kGy so as to enhance the treatment of the composites. Mechanical properties of the composites, such as tensile strength, elongation at break, tensile modulus, and cross-link density were enhanced by adding the treated fiber to SBR and by irradiation, and this enhancement was obtained at 6 phr fiber at 100 kGy. Measurements of scanning electron microscopy (SEM) proved the adhesion of the treated fibers to SBR. The thermal conductivity was measured for the prepared composites as a function of electron beam irradiation and fiber content. It was found that the thermal conductivity decreases according to fiber loading (up to 6 phr fiber) and irradiation dose. KEYWORDS electron beam irradiation, mechanical properties, newsprint, styrene-butadiene rubber, thermal conductivity, 1 | INTRODUCTION Quite recently, extensive consideration has been paid to recycling newsprint and utilizing it as a filer in a polymer matrix to acquire specific properties. Newsprint, alongside different [...]

By the use of a high-speed collection drum, poly(vinylidene fluoride) (PVDF) was electrospun into aligned ultrafine fibrous membranes from its solutions in a mixture of N, N-dimethylformamide and acetone (9:1, v/v), and a continuous hot-press post-treatment was performed on the membranes to improve their mechanical properties. Anisotropic tensile results and rupture behaviors of the hot-pressed PVDF membranes with higher fiber alignments in both revolving direction (RD) and cross direction were obtained. It was found that, due to the true fracture of electrospun fibers and improvement of the interfiber compaction by hot-press, the tensile strength and modulus of the hot-pressed membranes in RD reached the highest values at 58.12 ± 4.46 MPa and 519.9 ± 34.1 MPa, respectively when the collection speed was 10.42 m/s. The decrease of porosity and liquid absorption also represented the compaction improvement of the electrospun fibrous membranes. The combination of fiber alignments and hot-press could provide a novel method to fabricate high strength of electrospun membranes which have highly potential applications in filtration or battery separators. POLYM. ENG. SCI., 49:1291-1298, 2009. [C]2009 Society of Plastics Engineers, INTRODUCTION The electrospinning process has been studied as a useful method to produce ultrafine fibrous membranes from polymer solutions or melts under a high electric voltage for several years (1-5). [...]

Transient liquid phase diffusion brazing is used in precision, hermetic joining applications as a replacement for diffusion bonding to reduce cycle times, reduce bonding pressure, and improve yields. In the present study, stainless steel 316L laminae are diffusion brazed with an interlayer of nickel nanoparticles and compared with samples joined by conventional diffusion bonding and electroplated nickel-phosphorous diffusion brazing. Comparison is made with regard to microstructural evolution, diffusional profile, and bond strength. All bonding was carried out in a uni-axial vacuum hot press at 1000[degrees]C with a heating rate of 10[degrees]C/min, a dwell time of 2 h and a bonding pressure of 10 MPa. Bond strength measurements show that the sample brazed with a nickel nanoparticle interlayer has the lowest void fraction at 4.8 [+ or -] 0.9% and highest shear strength at 141.3 [+ or -]_7.0 MPa. Wavelength dispersive spectroscopic analysis of sample cross-sections shows substantial diffusion of Ni and Fe across the nickel nanoparticle bond line. Scanning electron micrographs show no secondary phases along the nickel nanoparticle bond line. [DOI: 10.1115/1.4001554] Keywords: diffusion brazing, nickel nanoparticle interlayer (NiNP), stainless steel 316, shear strength

Four different fabrication procedures were used for casting thin films of syndiotactic polypropylene (sPP). A hot press system operated at 200°C and 30 MPa pressure was used to melt polypropylene powder and make the cast films. Different cooling procedures were used to anneal the films, including cooling in liquid nitrogen (LN), ice water, and air at room temperature (RT). The morphological and mass transfer properties of the films were studied with XRD, polarized optical microscopy, bulk flow, and diffusion experiments. All sPP films contained amorphous and crystalline phases. The crystalline phase was determined to be disordered Form I. The sPP films annealed with LN had the lowest crystallinity whereas the sPP films cooled in air at RT had the highest crystallinity. Diffusion of toluene in the films and comparison with Maxwell's equation indicated that the crystalline phase mass permeability is much lower than the amorphous phase, which causes films with low crystallinity to have a higher effective diffusion constant and permeability compared with high crystallinity films. POLYM. ENG. SCI., 49:740-746, 2009. [C] 2009 Society of Plastics Engineers, INTRODUCTION Syndiotactic polypropylene (sPP) was first synthesized by Natta et al. in 1960s (1), (2), and improved sPP was reported by Ewen et al. (3) in the 1980s using a [...]

The authors present a study of the crystalline properties of selected series of polypropylene (PP) materials in relation to their warpage at conditions relevant for rotational molding. The PP materials have different crystallization temperatures and kinetics. The authors study the crystalline features of the materials using hot-press experiments and differential scanning calorimetry (DSC). In the DSC, the authors do constant cooling rate runs as well as isothermal crystallization and subsequent heating. A multimode crystallization kinetics model was fitted to the DSC cooling runs. Regression analysis was done to relate the results from the crystallization experiments to warpage. The derived empirical model shows that the crystallization temperature, crystallization half-time, and heat of fusion are the most significant parameters influencing warpage. Materials with warpage deviating from the model average are discussed taking aspects of the multimode kinetics into account. The present work could represent a basic platform for understanding and predicting the warpage during rotational molding process. POLYM. ENG. SCI., 49:523-530, 2009. © 2009 Society of Plastics Engineers, INTRODUCTION Rotational molding (RM) is a high temperature, low pressure, and shear-free process for production of hollow plastic articles. The process comprises a sintering phase followed by cooling and solidification. [...]

Well-defined nano-topographies were prepared by electron-beam lithography and electroplated to form nickel-shims. The surface pattern consisted of square pillars repeated equidistantly within the plane of the surface in a perpendicular arrangement. The width and distance between the squares both ranged from 310 to 3100 nm. All the pillars were 220 nm high. The nickel-shim was used as a surface-template during injection molding of polycarbonate. Secondly, a nickel shim, with a surface pattern consisted of a squared sine with a period of 700 nm and amplitude of 450 nm, was mounted on, and it was in good thermal contact with the upper plate in a hot-press. Polycarbonate/polystyrene was melted on the lower plate while the temperature of the shim was kept below the glass transition temperature. The upper plate was lowered until the shim was in contact with the melt. Experiments were carried out with a clean shim and a shim coated with a monolayer of fluorocarbonsilane. As a result of the surface coating, the amplitude of the replicated grating decreased from about 350 nm in polycarbonate and 100 nm in polystyrene to less than 10 nm. The experiments strongly suggest that the possibility to injection mold sub-micrometer surface structures in polymers mainly relates to adhesive energy between polymer and shim. POLYM. ENG. SCI., 46:160-171, 2006. [c] 2005 Society of Plastics Engineers, INTRODUCTION Recent years have shown an ever-increasing interest in topographically nanostructured polymer surfaces. Their current and projected applications include mass storage (Compact Disc/Digital Versatile Disc), nanolithography (sub-100 nm structuring of [...]

Several useful composite materials have been developed with natural fiber and plastic matrices, and their commercial viability has been established in terms of adding value to abundant and cheap natural resources. The Macromolecular Research Centre, Jabalpur, India, has recently developed composite from waste newspaper reinforced with plastic material using a prepreg technique wherein the matrix resin consists of resol type phenolic resin (PR) and bifunctional epoxy resin (EP) condensate. Laminates of newspaper and PR-EP condensate were prepared by hot press molding, and the newspaper weight fraction in these composites was varied from 0.30 to 0.65. The mechanical properties of five selected newspaper (PR-EP) condensate composites are reported for parameters such as ultimate tensile strength, elongation, tensile modulus, flexural strength and modulus, and heat deflection temperature (HDT). The water uptake behavior of these composites was examined by constructing water absorption isotherms, and the water diffusion coefficient and water absorption (24 h soak test) were determined. The specific tensile and flexural strengths and modulus properties of newspaper-(PR-EP) condensate composites are found comparable with one prepared elsewhere from recyclable newspaper-reinforced polypropylene thermoplastics., INTRODUCTION The opportunity of adding value to low-cost forest or agro based cellulosic material by formulating them in valuable composite materials has of late been exploited (1). Large sources of [...]

The melt-phase hydrosilylation of terminal double bonds in polypropylene (PP) was investigated. The double bonds were generated by peroxide initiated degradation of PP in an extruder or a batch mixer. For this purpose, an organic peroxide, Lupersol 101, was employed in concentrations of 0.5-5 wt%. A hydride-terminated polydimethylsiloxane was employed as a model substance to investigate the feasibility of hydrosilylating the terminal double bonds of the degraded polypropylene. Reactive processing experiments were carried out in a hot press, a batch mixer, and a single screw extruder. Two different reaction mechanisms were used to initiate the hydrosilylation reaction: a radical chain addition mechanism and a platinum catalyzed mechanism using Karstedt's catalyst. For the radical mechanism, it was shown that catalytic amounts of a peroxide could initiate the addition of silanes to the double bonds of the degraded polypropylene. Furthermore, it was found that both reactions, degradation and hydrosilylation, could be performed simultaneously. For the catalytic mechanism, the required stabilization of the platinum colloid formed in this mechanism was accomplished by adding t-butylhydroperoxide as a cocatalyst. This melt-phase hydrosilylation route may be used to produce terminally functionalized polypropylenes, and a case study involving the terminal attachment of a styrene functionality was examined., INTRODUCTION The hydrosilylation reaction, the addition of a silicon hydride to a multiple bond such as carbon-carbon, carbon-nitrogen, nitrogen-nitrogen, carbon-oxygen, and nitrogen-oxygen, was first reported in 1947 by Sommer et [...]

Dynamic mechanical properties, tensile properties, and scanning electron microscopy of blends of poly(methyl methacrylate) and polycarbonate were investigated after phase separation above their cloud point temperature by annealing in a hot press. The dynamic mechanical properties show that phase separation proceeds more distinctly for the blends annealed at higher temperature and for longer time. The scanning electron micrographs show that the morphology of phase separated blends varies with the conditions of heat treatment. The tensile properties of phase separated blends deteriorate on account of the coarsening of the brittle dispersed phase over the optimum size and the occurrence of voiding during the heat treatment.

Despite the wide range of applications of polyethylene (PE), many efforts are being made to improve its properties with carbon allotropes such as graphene. The addition of graphene can improve the electrical, thermal, and mechanical properties of this polymer. Through the present study, the effects of exfoliated graphene nanoplatelets (XGNPs) and few-layer graphene (FLG) on the electrical conductivity and thermal properties of high-density polyethylene (HDPE) were investigated. XGNPs were synthesized by ultrasonication of graphite nanoplatelets, and FLG was synthesized by shear exfoliation of flake graphite. Finally, HDPE powder particles were coated with dispersed XGNPs and FLG. Then XGNPs/HDPE nanocomposites and FLG/HDPE nanocomposites were fabricated by compression molding. The morphology, structural, electrical, and thermal properties of the graphite, graphene, PE, and nanocomposites were observed and comparatively studied by transmission electron microscopy, field emission scanning electron microscope, x-ray diffraction (XRD), Raman spectroscopy, and conductivity measurements. The graphene's D, G, and 2D bands were revealed by Raman spectroscopy of nanocomposites and verified the existence of the graphene in the polymer matrix. XRD revealed that the graphene did not affect the original crystalline structure of the HDPE matrix, and the Fourier-transform infrared spectroscopy revealed that the nanocomposite was obtained without the formation of any functional groups. The electrical properties of the nanocomposites were comparatively studied. After adding XGNPs (7 wt%), volumetric electrical conductivity in a sample reached from [10.sup.-16] to [10.sup.-3] S/m. The highest volumetric conductivity, 1.1 * [10.sup.-2] S/m, that is, semiconductor-like conductivity, was achieved after adding 7 wt% of FLG. The glass transition temperatures ([T.sub.g]), melting temperatures ([T.sub.m]), and thermal stability were investigated by differential scanning calorimetry and TGA, respectively, and it was concluded that [T.sub.g] and [T.sub.m] increase by adding the graphene. This study shows that shear exfoliation of graphene is the best and the most facile method to prepare mass-scale graphene for the production of graphene/polyolefin nanocomposites. Highlights * Two types of graphene were produced by using sonication and shearexfoliation. * HD PE powders were coated with two types of graphene and then hot pressed. * The method of (G) preparation is crucialparameter on electrical conductivity. * In the sample containing 7 wt% (XGNPs), the highest conductivity is [10.sup.-3] S/m. * In the sample containing 7 wt% (FLG), the highest conductivity is [10.sup.-2] S/m. KEYWORDS electrical conductivity, graphene, graphite, polymer nanocomposite, thermal properties, 1 | INTRODUCTION Polyolefins are among the most applicable plastics in the polymer industry. Polyethylene (PE) is a member of the polyolefin family, which is thermoplastics, and its products, especially [...]

Soy protein isolate (SPI), a widely available and inexpensive natural polymer, can be used as a filler to reduce the cost of poly(butylene adipate-co-terephthalate) (PBAT) materials. To improve the compatibility between SPI and PBAT, a series of polycaprolactone-based polyurethane prepolymers (PCLPUs) with different soft segment molecular weights were synthesized and used as compatibilizers to prepare SPI/PBAT composites. At the same time, the effect of PCLPU soft segment molecular weight on the properties of SPI/PBAT composites was studied. Structural, morphological, and property analyses were carried out on the composite materials; the results showed that PCLPU was an effective compatibilizer for SPI/PBAT composite materials. The -NCO group at its end forms a urethane bond with the hydroxyl group in SPI and PBAT. At the same time, the soft segment of PCLPU is physically crosslinked with PBAT to produce a dual physical and chemical effect. The lower the soft segment molecular weight of PCLPU added, the better the performance of the SPI/PBAT composite materials. This is observed because PCLPU with a lower soft segment molecular weight contains more -NCO functional groups, which can better achieve compatibilization between SPI and PBAT through chemical crosslinking. The addition of 5% PCLPU-500 content to the SPI/PBAT composite material increased its tensile elongation, impact strength, and tensile strength by 867%, 264%, and 150%, respectively, compared with those of the SPI/PBAT composite material without a compatibilizer, achieving toughening and strengthening with good processability and biodegradability. This work provides a simple, effective solution for preparing high-performance, green, and low-cost biodegradable composite materials. Highlights * PBAT composites were prepared using soy protein isolate (SPI) as filler. * Different types of PCLPU exist as a reactive compatibilizer for PBAT and SPI. * Polycaprolactone-based polyurethane prepolymer significantly improves the interfacial compatibility of PBAT composites. * SPI/PBAT film has good degradability and is a rich source of nitrogen. KEYWORDS biodegradation, composite film, PBAT, PCLPU, soft segment molecular weight, soybean protein isolate, 1 | INTRODUCTION Plastic is an essential organic synthetic polymer material with many applications. However, while bringing convenience to human life, the 'white pollution' caused by plastic is becoming increasingly [...]

This work focuses on developing a novel thermal-responsive shape memory Poly([epsilon]-caprolactone) (PCL)/maleic-anhydride grafted poly[styrene-b-(ethyleneco-butylene)-b-styrene] (SEBS-g-MAH) blends, with enhanced shape memory and mechanical properties, which is tailored for 3D printing applications. The thermal, mechanical, and rheological properties of the blends were rigorously assessed by DSC, TGA, mechanical testing, and dynamic rheological analysis. The results show that the elongation at the break of the blends exceeds 1000%, which can be attributed to the formation of the co-continuous structure. Thermal-responsive shape memory properties characterized by the water bath circulation method showed that the PCL4/MAH6 exhibited the optimal overall performance (shape fixation rate of 97.22%, shape recovery rate of 96.67%) and remained stable after 10 cycles of testing. Moreover, the effect of printing parameters on shape memory properties was investigated, revealing that blends perform the most promising memory behavior at a layer thickness of 0.1 mm, hot-bed temperature of 40[degrees]C, and printing speed of 40 mm/s. In addition, the relationship between the composition of the blends and their properties was investigated at the molecular level by molecular dynamics simulations, which were in agreement with the experimental observations. In conclusion, this study provides new perspectives on the development of advanced materials suitable for 4D printing applications. Highlights * The co-continuous structure effectively enhances blends' mechanical properties. * The storage modulus exerts a dominant influence on the shape memory properties. * Molecular dynamics simulations are employed to validate experimental observations. KEYWORDS 4D printing, mechanical properties, PCL/SEBS-g-MAH blends, shape memory properties, 1 | INTRODUCTION For decades, 3D printing has rapidly developed and emerged as a key domain within the field of rapid prototyping, which is also known as additive manufacturing. (1-3) [...]

Ethylene-propylene-diene monomer rubber, grafted with maleic anhydride functions (EPDM-g-MA) was organically reinforced by reactive extrusion from the in situ synthesis of a polyimide (PI) phase. The blends were reactively processed at 200[degrees]C in a twin-screw extruder, with the PI content varying from 5 to 40 wt%. Transmission Electron Microscopy (TEM) revealed a very fine nodular dispersion of the PI phase with diameters ranging from 130 to 240 nm depending on the PI concentration. The reinforcement of the elastomer was evidenced with a sharp increase of the Young's modulus and the tensile strength, and the stiffness of the material was further increased with the PI content. The linear viscoelastic regime, as measured by the variation in storage modulus as a function of strain, was unaffected by this organic reinforcement, thus opening up an original way of controlling the Payne effect. Additionally, the cross-linking of the blend with 20 wt% of PI with dicumyl peroxide (DCP) showed that the PI phase did not impact the creation of the cross-linked network. The decrease of the swelling ratio and the improvement of the elastic recovery suggested that EPDM-g-PI copolymers can create a second network in the material, resulting in a higher apparent cross-linking density. The mechanical properties of the cured blend showed a doubling of the Young's modulus and maximal stress values compared to those obtained for the pure matrix as well as a constant strain at break. Highlights * Ethylene-propylene-diene monomer rubber, grafted with maleic anhydride functions (EPDM-g-MA) was organically reinforced by reactive extrusion. * The reinforcement was obtained from the in situ synthesis of a polyimide (PI) phase. * The Young's modulus of cross-linked EPDM containing 20 wt% PI was doubled. * The linear viscoelastic regime was unaffected by this organic reinforcement. * This original way of reinforcement opens the control of the Payne effect. KEYWORDS EPDM, in situ polymerization, polyimide, reactive extrusion, reinforcement, 1 | INTRODUCTION Ethylene-propylene-diene monomer rubber (EPDM) is one of the most widely used synthetic rubbers. The presence of diene enables sulfur vulcanization or peroxide cross-linking with a high efficiency. [...]

This study explores the tribological properties of mollusk-shell-high-density polyethylene (MS-HDPE) biocomposites and diamond-like carbon (DLC)-coated metal beads as potential substitutes for hip joint prostheses. HDPE biocomposites with 0, 5, and 10 wt% of MS were developed using hot compression molding. Coatings included pure DLC, DLC-Si, and DLC W:H. Wear tests on a ball-on-disk tiibometer examined friction and wear rates against coated and uncoated balls, along with wear morphology. MS-HDPE demonstrated superior tribological performance against DLC, achieving a 67% reduction in specific wear rate compared to pure HDPE. The study suggests that 5 wt% MS-HDPE coupled with a DLC-coated counterpart coating could be a promising combination for orthopedic applications, presenting a potential solution to metal corrosion and wear debris issues in orthopedic implants. Highlights * Tested coatings: DLC, DLC-Si, and DLC W:H. * Biocomposite wear versus coated balls. * DLC coating improves wear with shell fillers. * Mollusk shell strengthens biocomposites. * Reduced wear rate by 63% and friction by 77%. KEYWORDS DLC coating, MS-HDPE biocomposite, wear morphology, wear resistance, 1 | INTRODUCTION Hip replacements have become a popular solution for people suffering from severe joint pain. (1) These prostheses are typically made of polymeric and metallic materials, with the [...]

In high-frequency applications such as 5G-6G communication, internet of things, automotive radar, and automated driver-assistance systems, substrate materials excel as insulating layers owing to their superior dielectric properties. However, traditional methods for material development are often laborious and costly. To overcome these limitations, we employed molecular dynamics (MD) simulations to predict the dielectric properties of these materials at frequencies exceeding[10.sup.7] Hz. Specifically, we selected thermosetting polyphenylene oxide (m-PPO) as the resin matrix and combined it with three crosslinking agents, respectively: triallyl cyanurate, triallyl isocyanurate, and trimethylallvl isocyanurate. Our overarching goal is to provide comprehensive insights into the development and enhancement of materials critical for high- frequency electronic devices. We anticipate that this methodology will be widely adopted for the development of advanced substrate materials across various applications, with the objective of effectively screening crosslinkers. Highlights * Developed a simulation method to efficiently explore material scenarios for high-frequency applications. * Studied the dielectric properties of m-PPO combined with three crosslinking agents at high frequencies. * Successfully predicted dielectric properties using MD simulations. KEYWORDS crosslinking structures, dielectric loss, high frequency, molecular dynamics, substrate materials, 1 | INTRODUCTION In the rapidly evolving field of advanced electronic packaging, there is a growing interest in substrate materials that exhibit low dielectric constant and low dielectric loss, particularly [...]

Polypropylene is a useful and widely consumed thermoplastic with very good properties that can be mixed with a combination of rubber and nanoparticles in order to eliminate its shortcomings. In this paper, the simultaneous combination of both the toughening effect of styrene-butadiene rubber (SBR) and the reinforcing effect of silicon carbide (SiC) nanoparticles were investigated in polypropylene matrix. Mechanical properties (tensile and impact strength [TS and IS]) of compounds were analyzed using the central composite design approach in Design-Expert software. With two factors for input variables of SBR and SiC weight percentages, and their five levels (5, 10, 15, 20, and 25) and (0, 1.5, 3, 4.5, and 6), respectively, the central composite design approach employs 11 experiments for creation of models and the analysis of variance investigations with two output responses of TS and IS. Statistical results revealed that SBR and SiC contents had a significant effect on TS, IS, and the microstructure of compounds, as confirmed by scanning electron microscopy and energy-dispersive spectroscopy images. To maximize all mechanical properties simultaneously with desirability functions, TS and IS of the optimum sample were computed to be 21.98 MPa and 8.66 kJ/[m.sup.2] in amounts of 13.45 and 2.80 weight percentage (wt%) of SBR and SiC, respectively. Highlights * By increasing silicon carbide (SiC) in polypropylene/styrene-butadiene rubber (SBR), tensile strength decreases after a peak due to agglomeration effect. * By increasing SiC in polypropylene/SBR, impact strength decreases after a peak due to agglomeration effect. * By increasing SiC, the rubber particles' dimensions decrease according to scanning electron microscopy analysis. * Simultaneous maximum of tensile strength and impact strength are 21.98 MPa and 8.66 KJ/[m.sup.2], respectively. * Optimum value of SBR and SiC in above maximums are 13.45 and 2.8 wt%, respectively. KEYWORDS mechanical properties, microstructure, optimization, PP/SBR/SiC nanocomposite, response surface methodology, 1 | INTRODUCTION In the last decades, polypropylene (PP) as an important commercial thermoplastic has been used to manufacture domestic appliances, automotive parts, packaging tools, electronic instruments, and construction components. [...]

To enhance water resistance of starch-based foam, based on the porous and irregular surface feature of foam, fumigating hexamethyldisilazane (HMDS) and spraying nano-Si[O.sub.2]/ethanol solution were utilized to enhance hydrophobic properties of the starch-based foam. Homemade starch-molded foams were used for hydrophobic modification studies, the results showed that fumigating HMDS can lead to the formation of 'Si-O-C' bonds between HMDS and starch. Additionally, it can form more stable 'Si-O-Si' bonds with nano-Si[O.sub.2] in the original composites, which can better adhere to the surface of the starch foam to effectively create a waterproof barrier layer. On the basis of HMDS fumigation modification, hydrophobicity was significantly enhanced by further spraying of nano-Si[O.sub.2]/ethanol solution. When the mass ratio of nano-Si[O.sub.2] to ethanol was 6:100, the combination of HMDS and nano-Si[O.sub.2] was optimal, while making the roughness of the foam surface suitable, at which time, the contact angle reached 155[degrees], the maximum value under this system, indicating that the hydrophobicity was optimal. The fumigation and spraying method can evenly and comprehensively act on the surface of the porous and irregular starch-based foam, which facilitates the waterproof post-treatment process of the industrial application process and has strong practical significance. Highlights * Fumigated with HMDS, the starch foam's exhibit some hydrophobic effect. * Fumigation followed by spraying is effective in enhancing the hydrophobicity of starch foams. * Both the fumigation method and the spray method are suitable for the posttreatment of hydrophobic of starch foams. KEYWORDS foam, fumigating, hydrophobicity, spraying, starch, 1 | INTRODUCTION In recent years, the preparation of foam products with starch instead of traditional industrial resins such as polythene, polyurethane, and polystyrene has become a popular area of [...]

Heat shrink sleeves (IISS) are multilayer polymers that provide corrosion resistance for welding joints of steel pipes. Within the HSS structure, the adhesive layer is a blend of components, such as ethylene vinyl acetate (EVA) and linear low-density polyethylene (LLDPE). In this study, a systematic approach was employed to investigate the effect of the rheology and blend composition of the maleic anhydride modified EVA and maleic anhydride-modified LLDPE (EVA-g-MA/LLDPE-g-MA) adhesive layer, prepared by melt processing, on its adhesion properties. Various characterization techniques were employed to investigate the local morphology of the prepared blends at different zones. Peel strength tests were used to characterise the adhesion strength of the prepared adhesives. Our findings demonstrate that lhe local distribution of EVA-g-MA within LI,DPE-g-MA plays a crucial role in tire adhesion strength of the adhesive. The results show that the adhesion strength enhanced by nearly 45% as the composition of EVA-g-MA at the surface went up by 20%, shifting the failure location from the epoxy/adhesive interface to the bulk of the adhesive layer. Our hypothesis of the decrease of EVA-g-MA intrachain bonding and increase in the EVA-g-MA free chain amount in the presence of LLDPE-g-MA to improve the adhesion properties was corroborated through our catorimetry resulta where the relative EVA-g-MA crystallinity decreased as LLDPE-g-MA was introduced to the blend. The findings of our study highlight the importance of rheological behavior and blend composition in obtaining optimized performance of adhesives within the HSS structure. Highlights * Compression molding of EVA-g-MA/LLDPE-g-MA induces a layered morphology. * Local distribution EVA-g-MA/LLDPE-g-MA components influence their adhesion. * EVA-g-MA at the interface improves the adhesion of EVA-g-MA/LLDPEg-MA. * LLDPE-g-MA suppresses the EVA-g-MA cry stallinity. * EVA-g-MA/LLDPE-g-MA composition affects adhesion at different temperatures. KEYWORDS adhesion, EVA-g-MA/LLDPE-g-MA blends, morphology, phase separation, rheology, 1 | INTRODUCTION Multilayer polymers have gained widespread attention and popularity due to their numerous advantages over other polymeric composites. (1,2) Combining different polymers and the proper design of a [...]

Thixomolding is a method of molding thixotropic semi-solid magnesium alloy pellets in a machine that resembles an injection molding machine in physical appearance and operation. Thixomolding was derived from the [...]

Thermal Technology, Santa Rosa, Calif., built, installed, and commissioned a 500,000-lbf hot press for a northern California company to produce large powder metallurgy semiconductor materials. Model HP500-242424G offers a large [...]

We report efficacious vibration damping of carbon black reinforced nitrile butadiene rubber-polyvinyl chloride blend (NVC) vulcanizates in a constrained layer damping (CLD) configuration. The objective is to compare numerical simulations using finite element method (FEM) and the widely used Ross-Kerwin-Ungar (RKU) model with the experimental results. NVC blend (50:50 by weight), was compounded with carbon black as reinforcing filler and vulcanized using a sulfur-based curative system. Significant reinforcement and toughening were observed for the carbon black reinforced vulcanizates compared to the pristine blend. The viscoelastic properties of the vulcanizates were assessed using dynamic mechanical analysis (DMA), exploring their behavior concerning temperature variations and different frequencies to generate the Prony series coefficients for input in FEM analysis. Vibration damping experiments were conducted using the Oberst beam method in a single cantilever mode, with steel as the vibrating substrate, aluminum as the constraining layer, and the NVC vulcanizates as viscoelastic materials (VEM). Numerical simulations were performed using FEM to analyze mode shapes and frequency response function (FRF), and the RKU model was employed to quantify CLD system loss factors (SLF). The salient finding of this study was the observed SLF values in the range of 0.08-0.20 in the frequency regime of 200-2000 Hz. These values qualify the studied material as effective VEMs for CLD treatment of structural vibrations. This study supports design optimization efforts in a wide range of engineering applications where effective vibration damping is critical. Highlights * Enhancement of NVC blend properties through carbon black reinforcement. * Detailed analysis of viscoelastic behavior using DMA. * Validation of findings through experimental modal analysis. * Promising results in terms of system loss factors for CLD applications. KEYWORDS carbon black, constrained layer damping, dynamic mechanical analysis, finite element method, PVC-NBR blend, Ross-Kerwin-Ungar model, 1 | INTRODUCTION The issue of uncontrolled mechanical vibration is prevalent in various domains, leading to the reduced operational efficiency of instruments and creating disturbances in the work environment. While [...]

The purpose of this paper was to show how modified benzoxazine resin/ ethylene-propylene-diene monomer rubber/Kevlar composites are prepared. The compatibilization of polar benzoxazine resin and non-polar EPDM was carried out by EPDM-g-MAH copolymer synthesized as a compatibilizer, and then, the microwave (MW) irradiation method and conventional thermal cure (CV) were used to cure this composite. The samples cured by both methods were evaluated and compared by differential scanning calorimetry analysis (DSC), dynamic mechanical thermal analysis (DMTA), scanning electron microscope (SEM), and thermo-gravimetric analysis (TGA). Microwave curing significantly reduced the curing time, and the composites cured with MW irradiation had higher glass transition temperature (Tg), more uniform curing, higher cross-link density, and more thermal stability than CV-cured composites. Highlights * Constructing BZ/EPDM/Kevlar thermal composite for use at high temperatures. * Using modified resin to reduce curing temperature and improve final properties. * Creating compatibility between non-polar EPDM rubber and polar BZ resin. * Investigating and comparing between thermal and MW curing of the composites. KEYWORDS composites, curing of polymers, microwave irradiation, thermal properties, 1 | INTRODUCTION Composites have gained many applications in various industries such as aerospace, marine, electrical, and other industries. So, these modern composites have been a good substitute for metals, [...]

A novel approach of electrical impedance spectroscopy (EIS) is proposed to investigate the role of a compatibilizer on nanoparticle distribution in polymer blends with a co-continuous morphology. Polypropylene/poly(ethylene-co-vinyl acetate) PP/EVA blends containing 3 vol% carbon nanotubes (CNT) with varying contents of polypropylene-grafted- maleic anhydride (PP-g-MA) as compatibilizer were directly melt mixed. Microscopy, rheology, and thermodynamic analyses confirmed the distribution of CNTs in PP, EVA, and their interface. The EIS behavior of the blend nanocomposites was remarkably changed due to the formation of interphase by PP-g-MA/CNT. It was found that as the efficiency of compatibilizer increases the frequency dependency of the impedance diminishes showing a significant shift in the frequency cutoff from [10.sup.4] Hz to 5 * [10.sup.5] Hz. The EIS results also showed that compatibilizer can affect the loss factor. Incorporating 5 vol% or 10 vol% of the compatibilizer slightly reduced the loss factor, but a considerable reduction was observed at 20 vol% at which a conductive continuous interphase of compatibilizer formed at the interface. Moreover, the presence of compatibilizer led to a remarkable increase in dielectric constant by four orders of magnitude. EIS can effectively and comfortably trace the performance of a compatibilizer in a conductive polymer blend nanocomposite. Highlights * EIS measurements describe microstructure of conductive polymer blend. * EIS detects morphology development of a compatibilizer at varying contents. * Migration of compatibilizer intensifies the Nyquist diameter decrement. * Compatibilizer decreases dielectric relaxation time. KEYWORDS compatibilizer, dielectric properties, EIS, frequency cut-off, polymer blends, polymer nanocomposites, 1 | INTRODUCTION Conductive polymer nanocomposites (CPNCs) have emerged as a promising class of materials due to their unique combination of electrical, mechanical, and thermal properties. (1,2) These materials consist [...]

The fracture behavior of specimens made of polylactic acid and weakened by inclined double keyhole notches is investigated by both experimental and numerical methods. The test specimens are fabricated by two different methods; fused deposition modeling and traditional methods. The mechanical behavior of specimens was investigated under mixed-mode loading with different notch inclination angles, various notch tip radius, and multiple raster angles. An experimental program was performed, and 72 new experimental data were provided. A fracture criterion based on the strain energy density is used to assess the critical fracture loads of the tested specimens. Good agreement is found between experimental and numerical data. The results showed that increasing the notch inclination angle and notch tip radius led to a decrease in the fracture load of the specimens. Also, fracture loads of the classical specimens are higher than the 3D-printed specimens. In the 3D-printed specimens, fracture loads for the samples with raster angles of 0[degrees], 45[degrees], and 90[degrees] have the highest value, respectively. Highlights * Fracture assessment of polylactic acid specimens * Specimens were weakened by using an eccentric inclined double keyhole notch * Specimens manufactured by fused deposition modeling and traditional method * Investigation of different notch inclination angles and notch tip radius * Evaluation of specimens using experimental and numerical analysis methods KEYWORDS additive manufacturing, double keyhole notch, fracture assessment, fused deposition modeling, polylactic acid, strain energy density, 1 | INTRODUCTION Polylactic acid (Pla) is a biological polymer that has a natural origin. The absence of toxic fumes and unpleasant odors during the manufacturing process are the positive [...]

Styrene/methyl methacrylate (St/MMA) copolymer-silica nanocomposite foams were prepared using supercritical C[O.sub.2] as blowing agent, and the relationships between their cellular microstructure and mechanical properties were investigated. The effects of nanosilica content, size, and surface chemistry on the foam's microstructure and properties were examined. Dispersion and distribution of silica nanoparticles with different surface chemistry in St/MMA copolymer nanocomposites were discussed. To determine the most suitable copolymer composition for incorporating silica nanoparticles, some operating conditions such as temperature and pressure were primarily examined to study their effects on the microstructure of resulting foams. In compressive mechanical properties of final foams, a considerably high value was obtained for the compressive strength of the foams of up to 9.5 MPa. The prepared low-density (below 0.2 g/[cm.sup.3]) St/MMA copolymer microcellular foams can be used in green lost foam iron casting processes. Highlights * Styrene/methyl methacrylate copolymer-silica nanocomposite foams were prepared via supercritical C[O.sub.2]. * Foams' cell size was changed by changing silica nanoparticle surface chemistry and size. * The uniform cellular microstructure was achieved by nanosilica size increment. * Increasing nanoparticle size improved the foam's mechanical properties. * Low-density foams were achieved for potential application in lost foam casting. KEYWORDS cellular microstructure, lost foam foundry, mechanical properties, nanosilica, St/MMA copolymer, supercritical C[O.sub.2], 1 | INTRODUCTION Because of the world energy crisis, scientists are very much interested in the development of lightweight and high-mechanical-property materials. (1-4) Producing such materials is viable by the [...]

Ethylene-propylene-diene monomer (EPDM) rubber has widespread uses in various applications due to its ozone and oxidation stability, weatherability, electrical insulation, and elasticity. However, its further use is limited by low flame retardancy and low thermal stability. This study incorporated metal hydroxide flame retardant to enhance flame retardancy and electron beam cross-linking to simultaneously enhance mechanical properties, thermal stability, and flame retardancy. The utilization of electron beam irradiation resulted in an increase in gel content and a decrease in swelling ratio with increasing absorbed doses, indicating the successful formation of cross-linked network structures. The hot-set elongation was significantly reduced to 0.6%-0.8%, while the decomposition temperature increased with increasing absorbed doses, indicating improved thermal stability. The results from limiting oxygen index measurements and burning tests demonstrate that the flame retardancy of EPDM was improved by the combined effect of metal hydroxide flame retardant and electron beam cross-linking. Highlights * EPDM/metal hydroxide composites were prepared via electron beam irradiation. * Metal hydroxide flame retardants were incorporated to enhance flame retardancy. * EBI simultaneously enhanced mechanical property and thermal stability. KEYWORDS cross-linking, electron beam irradiation, ethylene-propylene-diene monomer rubber, gel content, limiting oxygen index, mechanical property, thermal stability, 1 | INTRODUCTION Ethylene-propylene-diene-monomer (EPDM) rubber is a versatile synthetic rubber composed of ethylene, propylene, and a small amount of unsaturated dienes, such as ethylidene norbornene (ENB), dicyclopentadiene (DCPD), and [...]

Polymer-based composites containing functional organic fillers with polyvinylidene fluoride (PVDF) as a matrix were prepared using a simple and short melt-compounding method, and their mechanical properties were evaluated. Polyrotaxane and nanocellulose were used as functional organic fillers. A PVDF/organic filler composite with improved mechanical hardness was prepared, even when using a fluoropolymer that tends to separate phases from other components. The optimum conditions for improving in Young's modulus were estimated from the composites prepared by varying the organic filler content. As a result, the Young's modulus increased to 1548 MPa, maximum stress approached 50 MPa, and strain elongation was 20% at contents of polyrotaxanemanocellulose = 0.6 wt%:0.3 wt%. Furthermore, the miscibility of both components was evaluated based on the change in the crystallization temperature of the composite, the PVDF matrix, and each organic filler. The partial miscibility and dispersion of the organic fillers in the fluoropolymer matrix are suggested to be responsible for improving the mechanical properties. Highlights * Unique composites containing nanocellulose and polyrotaxane were prepared. * Organic fillers were introduced into a phase-separable fluoropolymer matrix. * Mechanical properties were improved by introduction of organic fillers. * Nanocellulose seems to adsorb to the polymer chain ends of fluoropolymer. * Polyrotaxane showed partial miscibility with fluoropolymer matrix. KEYWORDS compositemelt-compounding, nanocellulose, polyrotaxane, polyvinylidene fluoride, 1 | INTRODUCTION Fluorinated polymers are polymeric materials that tend to phase-separate from other components. (1,2) Typical crystalline fluoropolymers are the perfluorinated polymers of polytetrafluoroethylene (PTFE), (3,4) perfluoroalkoxyalkane (PFA), (5,6) [...]

[alpha]-form crystalline isotactic polypropylene (PP) was prepared by two methods: quenching from the melt state at slow or high crystallization rates. The mechanical properties of the resulting PP samples were evaluated using tensile and stress-relaxation tests to investigate the influence of nodular or spherulite morphologies. PP samples with different morphologies had almost the same crystallinity after annealing at 100[degrees]C for 5 h. The yielding stress, strain-hardening modulus, and strength of the nodular PP were higher than those of the spherulite PP, although the crystallinity was almost the same for both PP samples. Furthermore, the relaxation time during the stress-relaxation process at [epsilon] = 4.0 was longer for the nodular PP than for the spherulite PP. The lamellar structure of a spherulite morphology comprises parent and daughter lamellar crystals, whereas that of a nodular morphology prepared via a mesophase structure comprises only parent lamellar crystals. The formation of the daughter lamellae reduces the number of tie chains. Therefore, the nodular PP has more tie chains than the spherulite PP. This transformation from a spherulite to a nodular morphology improved the mechanical properties of the PP. Highlights * Influences of morphology on mechanical properties of polypropylene (PP). * Tensile properties were higher for nodular PP than spherulite PP. * Relaxation time of nodular PP was longer than spherulite PP. * Nodular PP has more tie chains, resulting in improvements of tensile properties. KEYWORDS isotactic polypropylene, tensile property, tie chain, 1 | INTRODUCTION Polypropylene (PP) has excellent properties and is therefore one of the most widely used semicrystalline polymers. The mechanical properties of PP strongly depend on the tacticity of [...]

Abstract This study used ethylene-propylene diene monomers (EPDM), an elastomer, to develop foams incorporating clay as filler using simple compounding, chemical foaming, and peroxide-mediated light crosslinking methods. The lowtemperature batch [...]

Abstract In this study, the formation of clay nanolayer clusters inside the high-density polyethylene (HDPE) matrix was evaluated using a specific strategy based on energy equilibrium in the melt mixing [...]

Thermoplastic materials have received extensive attention for their excellent mechanical properties and reproducibility, and have been emerging in lightweight accessories. However, for the traditional thermoplastic vulcanized (TPV) rubber, the dynamic vulcanization process makes it difficult to achieve low density and good compression performance. Herein, lightweight propylene butene copolymer/ethylene propylene diene monomer (PPB/EPDM) blend foam was prepared by static vulcanization of PPB and EPDM blend and supercritical nitrogen (sc-[N.sub.2]) foaming technology. The minimum density and compression set of the PPB/EPDM blend foam were 0.065 g/[cm.sup.3] and 13.6% respectively, a significant improvement was obtained compared with TPV. In addition, the PPB/EPDM blends retained the mechanical properties after seven times reprocessing, and the blend foam had similar cell structures to that of dynamic vulcanized TPV foam because of the phase transition of PPB/EPDM blend during reprocessing. This work provided an idea for the preparation of high-performance, lightweight, and recyclable thermoplastic materials. KEYWORDS mechanical properties, polymer blends, reprocessing, supercritical foam, vulcanization, 1 | INTRODUCTION Plastic and rubber are two important branches of polymer materials. [1-3] Based on the excellent mechanical properties of vulcanized rubber and the thermoplasticity of plastics, [4] rubber/plastic [...]

An ongoing effort to advance various energy systems (nuclear, solar, geothermal, and fossil) is underway around the world to meet the increasing demand for clean, affordable, and resilient energy, while [...]

Highly polar and hydrophilic polymers; ethylene-vinyl acetate (EVA), epichlorohydrin rubber (GECO), and polyethylene oxide (PEO) reinforced with fillers (carbon black (CB) and/or Silica) were used to prepare water-swellable rubber nanocomposites. The study showed that although the high content of the GECO delayed vulcanization of the corresponding compounds, the sample filled with desired ratio of GECO/PEO/EVA or GPE, cross-linked with peroxide exhibited the highest swelling performance of ~150%. The samples exhibited good re-usability performance in the re-swollen test, after drying. At prolonged water swelling, the tensile strength dropped drastically for compounds with high content of the GPE, due to weak filler-matrix interactions. On the other hand, the incorporated GPE also increased the rebound resilience (%) property which is a key requirement in green tire fabrication. For example; peroxide cured sample coded SR3 (GPE-15 phr CB) obtained ~30% resilience in non-swollen state and ~53.5% after 1440 min of water-swelling, which represents a dramatic development of over ~78% in rebound resilience. Thus, a proper balance between the GPE content, curing agent and the reinforcements may guarantee high water-swelling performance and mechanical properties integrity for multifunctional applications such as wound healing, structural works, water collection from oil spillages, and for the development of water-based sensors. KEYWORDS composites, elastomers, mechanical strength and resilient, rubber, swelling, volume expansion, water, 1 | INTRODUCTION The unique properties of visco-elastic polymers which include; strength-to-weight ratio, impact resistance, wear resistance, corrosion resistance, and others can be enhanced when they are reinforced with desired [...]

Abstract Covalent bond cross-link networks endow rubber with unique resiliency enabling it to be widely used as a series of irreplaceable materials in modern life. However, the balance between rigidity [...]

Abstract Perfect crisscross chain arrangements with high inter-chain H-bonding structure of conjugated polyamides are capable of inter-chain proton transfer and this property of conjugated polyamides makes them semiconducting material. To [...]

Abstract The hot-tack properties of ethylene-methacrylic acid copolymers neutralized with sodium (Na) cations to produce ionomers were investigated. Specimens with neutralization degrees of 20%, 54%, and 70% were examined. After [...]

Concerned about environmental pollution, and aware of the comfort that polyethylene provides for daily human life, this work sought to replace a percentage of high-density polyethylene (HDPE) with human or bovine hair. Hair is natural, abundant, light weight, non-toxic, and disposed of as garbage. The main disadvantage of natural composites is the interfacial adhesion. To increase the interfacial adhesion between hair and HDPE, stearic acid or oleic acid was chemically anchored on the hair surface, which leads to an improved contact angle hysteresis and hydrophobicity. Dynamic-mechanical properties of the composites were investigated focusing on the type of carboxylic acid used (stearic or oleic acid), hair length, hair type (human or bovine) and amount of hair used in the composite. Taking 40[degrees]C as a reference, using 15% of hair with a length of 1 [+ or -] 0.15 mm, the highest storage modulus value was obtained with HDPE with human hair modified with oleic acid, exceeding the value of the storage modulus of HDPE by 67.64%. Increasing storage modulus on composites indicates of interfacial interaction and chemical affinity improvement between hair and polyethylene. KEYWORDS bovine hair, carboxylic acids, composites, human hair, polyethylene, storage and loss modulus, 1 | INTRODUCTION Plastics are probably the most versatile materials we know, the demand for plastic raw materials is enormous, and the global production of plastics has increased from 2 [...]

The market demand for elastomeric-graphene/derivatives nanosheets (GDS) materials is high nowadays, due to their excellent physicomechanical properties over traditional composites. However, the curing behavior of elastomeric-GDS which influences the overall properties and also determines the cost of related products has not been well investigated. Previously, the curing properties of NBR-graphene oxide (GO) and NBR-reduced graphene oxide (rGO) was studied and the curatives (accelerator and activators) were suspected to have influence on their curing behavior. This study explores the curing behavior of NBR-GO and NBR-rGO in the absence of tetramethylthiuram disulfide (TMTD) accelerator. The virgin NBR exhibited shorter curing periods with higher curing rates (CRI) than the composites. The measured CRI showed close correlation with the activation energy [E.sub.a], deduced from Ozawa and Kissinger kinetics models. The NBR-rGO composites showed shorter scorch time and lowered [E.sub.a] at higher temperatures, with increased tensile properties than NB-GO composites. Despite the delay, the composites exhibited high strength over the virgin NBR, due to tighter networks introduced by rGO and GO sheets within NBR. Therefore, future design of elastomer-GDS-based composites must involve a careful control of the amounts of the accelerator-/co-accelerator-like TMTD in the mixtures for improved physico-mechanical properties of the final product. KEYWORDS acrylonitrile rubber, activation energy, cure accelerator, graphene oxide, reduced graphene oxide, vulcanization, 1 | INTRODUCTION Composites of elastomers reinforced with carbon-based fillers (CBF) such as carbon nanotubes (CNTs), carbon blacks (CB), and graphene/derivatives nanosheets (GDS) have been the hottest topics in rubber [...]

MULTIFUNCTIONAL MAGNETIC MATERIAL A research team from Australia's Flinders University created a new material that can be moved remotely with a magnet. The multifunctional material, made from magnetic iron particles [...]

Improving the flame retardant performance of polycaprolactam (PA6) will greatly expand its applications. At present, the commonly used reactive flame retardants of PA6 mainly come from the petrochemical industry. Therefore, D-glucopyranose, a green renewable biomass, is selected and bonded to the PA6 molecular chain through in situ polymerization to obtain a series of flame retardant polyamides (PA6/G1) and their high-speed melt-spun fibers. When its added amount was 2 wt%, the LOI and UL-94 of PA6/G1 reached 29.4 Vol% and V-0 level, and the char residue was 529.4% higher than that of neat PA6 after thermogravimetric test. D-glucopyranose contains a polyhydroxy structure that can capture the hydrogen radicals generated by homogeneous cracking during combustion, increasing the content of C[O.sub.2] and [H.sub.2]O and forming a smooth and dense carbon isolation layer. Thus, the synergistic flame retardant effect of green D-glucopyranose on the gas and condensed phases of PA6 is achieved. KEYWORDS D-glucopyranose, fiber, flame retardant, polyamide 6, 1 | INTRODUCTION Polycaprolactam (PA6) fiber refers to a type of synthetic fiber whose molecular chain is connected by amide bonds (--CO--NH--), and is the second synthetic fiber to realize [...]

In this work, the effect of the addition of reduced graphene oxide (rGO) nanoflllers to UHMWPE was investigated. The UHMWPE/rGO nanocomposites were prepared at rGO contents of 0.010, 0.10, 0.25, and 0.50 wt%. The morphological, mechanical, and surface properties of the nanocomposites and the neat UHMWPE were evaluated and related with their tribological behavior. For that, DSC, SEM, contact angle, MO, and profilometry techniques, besides shore D hardness tests, instrumented indentation tests and pin-on-disc sliding wear tests were performed. The results showed that nanocomposites with rGO contents of 0.10 and 0.25 wt% exhibited higher crystallinity degree than the neat UHMWPE, which improved significantly their mechanical and tribological behavior through increases of around 40% in the instrumented hardness and the elastic modulus, and a significant reduction of up to 48% in the coefficient of friction when compared to the neat UHMWPE. Additionally, the presence of rGO decreased the work of adhesion of the nanocomposites/ counterface pairs, resulting in friction and wear mechanisms changes in comparison with the neat polymer. KEYWORDS friction, nanocomposites, reduced graphene oxide, sliding wear, UHMWPE, work of adhesion, 1 | INTRODUCTION Ultra-high molecular weight polyethylene (UHMWPE) has been extensively used in engineering applications that involve wear and friction due to their self-lubricity, lightweight, corrosion resistance, and low coefficient [...]

Two kinds of modified melamine-formaldehyde (MF) resin with high impact strength were prepared, especially the modified MF resin with the special 'building blocks' structure. First, three copolymers (HMM-PEGDGE, HMM-PPGDGE, and HMM-[C.sub.12-14]AGE) of glycidyl ether [polyethylene glycol diglycidyl ether (PEGDGE), polypropylene glycol diglycidyl ether (PPGDGE), [C.sub.12-14] alkyl glycidyl ether ([C.sub.12-14]AGE)] and hexahydroxymethyl melamine (HMM) were synthesized and proved by FTIR and [sup.1]H NMR. Then, the copolymers were mixed with melamine-formaldehyde resin water solution to prepare samples (EMM1-PEs, EMM1-PP, and EMM1-[C.sub.12-14]) through drying and hot pressing. The results indicated that the addition of HMM-PEGDGE could significantly improve the impact strength of EMM1-PEs, much higher than EMM1-PP and EMM1-[C.sub.12-14]. Meanwhile, PEGDGE was also directly mixed with melamine-formaldehyde resin water solution and made into samples (EMM2-PEs). The results showed that the impact strength of EMM2-PEs was also higher than pure MF but lower than EMM1-PEs. The impact strength of EMM1-PE-20 reached 9.46 kJ/[m.sup.2], about two times that of pure MF. The mechanism of EMM1-PEs with high impact strength was ascribed to the special 'building blocks' structure, which had the flexible HMM-PEGDGE block, could cause many cracks because of the poor compatibility between HMMPEGDGE and melamine-formaldehyde resin. KEYWORDS copolymer, Glycidyl ether, impact strength, melamine-formaldehyde resin (MF), 1 | INTRODUCTION Melamine-formaldehyde resin (MF) is a thermosetting resin synthesized by polycondensation reaction of melamine (M) and formaldehyde (F). [1,2] Because of its good mechanical properties and flame retardant [...]

A comparative study on two nanocomposites based namely on acrylonitrilebutadiene (NBR) and styrene-butadiene (SBR) synthetic rubbers, reinforced by varying ratios of waste nanomarble particles (WM) was carried out. Silane which served as coupling agent was applied in treating waste marble (TWM) and the characters of the prepared nanocomposites before and after treatments were examined. Nanocomposites were fabricated using a laboratory roll mill and pressed under heat, then irradiated with gamma-rays at 100 kGy. Filler characterization, using the techniques transmission electron microscopy (TEM), FTIR spectroscopy, and X-ray diffraction (XRD) were discussed. TEM micrographs revealed that though untreated WM particles were within the nanometer scale, however showed incremental reduction in size via silane treatment. Mechanical parameters, thermal stability, FTIR and scanning electron microscopy (SEM) of the advanced NBR and SBR nanocomposites have been studied. Filler loading with 5 wt% led to remarked improvement in the tensile strength (TS), modulus of elasticity (M100), and tearing strength of the NBR nanocomposite samples. Meanwhile, elongation at break of SBR nanocomposites exhibited regressive behavior. Thermal stability testing of pristine NBR and SBR specimens demonstrated adverse features by compounding with untreated and treated waste nanomarble. Furthermore, gamma irradiated NBR nanocomposites reinforced with TWM indicated appreciable development at all thermogravimetric stages. Whereas, irradiation of SBR nanocomposites with a gamma integral dose of 100 kGy resulted in slight enhancement in thermal stability. KEYWORDS gamma irradiation, NBR and SBR nanocomposites, TEM, thermomechanical properties, waste nanomarble, 1 | INTRODUCTION Egypt yields over 50 different types of marble with yearly manufacture of about 3.5 million tons. [1] After mining in the quarries, industrial procedures based on splitting, [...]

In a manner of addressing challenges in scalable processing of thermoplastic polyurethane (TPU) nanocomposites through extrusion methods, this study reports a very clean processing approach of incorporating cellulose nanocrystal (CNC) into a TPU matrix, with no acid or organic-solvents usage. It involves a mechanical deconstruction of microcrystalline cellulose (MCC) into nanoscale particles in water and polyol through scalable bead-milling, vacuum drying, and followed by twin-screw reactive extrusion with isocyanate and chain extender. The thermal stability of CNC was higher than that of typically acidhydrolyzed CNC and suitable for processing with the precursors of TPU at typical processing temperature range (175-190[degrees]C). The CNC incorporation at very low loadings (0.5, 0.8 wt%) through this methodology resulted in substantial enhancements in tensile properties (for example, up to 28% in strength and toughness) without any significant stiffening effect Moreover, the nanocomposites retained elastic properties, including elongation at break (%), resilience, and creep resistance. Their chemical properties and thermal transitions were also found to support the retained thermoplastic behavior while improving mechanical performance. KEYWORDS cellulose nanocrystal (CNC), microcrystalline cellulose (MCC), nanocomposites, reactive extrusion, thermoplastic polyurethane, 1 | INTRODUCTION The improvement or modification of polymer properties using a wide range of nanoscale particles has been explored for last four decades. [1] In the field of polymer [...]

Natural rubber latex (NRL) is a natural polymer with versatile properties. However, uncured NRL has low strength and limited practical use. Therefore, we utilized low-dose gamma irradiation to induce cross-linking in blended NRL/poly(styrene-block-isoprene-block-styrene) (SIS). Blends were prepared in various ratios, and the [70.sub.NRL]/[30.sub.SIS] blend gave optimal mechanical properties. The [70.sub.NRL]/[30.sub.SIS] blend was then irradiated from 4 to 16 kGy. An exposure of 12 kGy led to the highest tensile strength (4.49 MPa), Young's modulus (0.41 MPa), gel content (45%), and cross-link density (12.18 x [10.sup.-5] mol*[cm.sup.-3]). The results of study show irradiation has improved the crystallinity of the polymer blend, which has been determined by the formation of a new NRL crystal peak at 31.2[degrees] and the decrease of the crystallization temperature from 58 to 19[degrees]C due to strain-induced crystallization. Moreover, the radiation has transformed the [70.sub.NRL]/[30.sub.SIS] blend irradiated at 12 kGy from liquid-like to an elastic state that degraded at a higher temperature (392.01[degrees]C). The presence of a singlet alkyl radical peak was detected in the electron spin resonance. Therefore, the cross-links are proposed to be C-C bonds formed via the radiation technique. Irradiation is an effective technique to improve the performance of NRL/SIS blends without introducing any chemical cross-linking additive. KEYWORDS block copolymer, cross-linking, gamma irradiation, natural rubber, 1 | INTRODUCTION Rubber is a type of elastomer that is available in both natural and synthetic variations. A recent study compared the life cycles of natural rubber (NR) and [...]

This work aims at studying the mechanism involved in the phase coarsening of ternary tri-continuous polymer blends. To this aim, the phase coarsening behaviors of a co-continuous polyethylene (PE)/polyethylene oxide (PEO) blend, and a tri-continuous PE/polycaprolactone (PCL)/PEO blend during the quiescent annealing process are studied. Rheological characterization showed that the zero-shear viscosities of PE and PCL phases were similar but much less than the zero-shear viscosity of the PEO phase. The evolution of the microstructure of the blends during annealing was characterized using a characteristic length scale ([lambda]). It was found that [lambda] in both co- and tri-continuous blends increased linearly in the early stages of annealing but the phase coarsening rate decreased in both systems at longer annealing times. In general, the tri-continuous blend showed much faster phase coarsening rate. The effects of kinetic and thermodynamic parameters on the observed phase coarsening behaviors are discussed in detail. A new lubricating mechanism is proposed in which the deformation of the PCL layer between PE and PEO phases reduces the effect of high viscosity of the PEO phase and increases the phase coarsening rate in ternary blends. The obtained results provide a new insight into the role of the middle layer in tri-continuous polymer blends on controlling the phase morphology of these systems. KEYWORDS annealing, blends, morphology, phase coarsening, tri-continuous, 1 | INTRODUCTION The wide range of properties and high design flexibility of binary polymeric systems provides a unique tool in designing polymeric systems with a desired set of properties. [...]