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The processing conditions were varied during the production of polycarbonate-based composites with the multiwalled carbon nanotubes (MWCNTs) Baytubes® C150 P (Bayer MaterialScience AG, Leverkusen, Germany), by melt mixing with an extruder on a laboratory scale. These included the screw design, rotation speed, throughput, feeding position and MWCNT content. Particular attention was paid to the shortening of the MWCNT length as a function of the conditions mentioned. It was found that there is a correlation between the applied specific mechanical energy (SME) during the melt mixing process and MWCNT dispersion, which was quantified by the agglomerate area ratio of the non-dispersed nanotubes based on optical microscopic analysis. The higher the SME value, the lower this ratio, which indicates better dispersion. Above an SME value of about 0.4 kWh/kg, no further improvement in dispersion was achieved. The MWCNT length, as measured by the quantitative analysis of TEM images of the MWCNTs dissolved from the composites, decreased with the SME value down to values of 44% of the original MWCNT length. At a constant loading of 3 wt.%, the tensile strength and tensile modulus were almost independent of the SME, while the elongation at break and notched impact strength showed an increasing trend. The variation in the feeding position showed that feeding the MWCNTs into a side feeder led to slightly better electrical and mechanical properties for both types of MWCNTs studied (Baytubes® C150 P and Nanocyl™ NC7000 (Nanocyl S.A., Sambreville, Belgium)). However, feeding into the hopper led to better CNT dispersion with Baytubes® C150 P, while this was the case with Nanocyl™ NC7000 when feeding into the side feeder. The screw profile had an influence on the dispersion, the MWCNT length and the electrical resistance, but only to a small extent. Distributive screws led to a greater shortening of the MWCNT length than dispersive screws. By varying the MWCNT content, it was shown that a greater MWCNT shortening occurred at higher loadings. Two-stage masterbatch dilution leads to stronger shortening than composite production with direct MWCNT incorporation. [ABSTRACT FROM AUTHOR]

Innovative melt processing technology is necessary for the production of biodegradable polylactide/graphene nanocomposites. In this paper, we present the aqueous spray coating method to prepare graphene-coated polylactide granules for improving the distribution of small graphene contents in polymer matrix during the melt mixing process. Three types of functionalized graphene nanosheets, including graphene oxide (GO), reduced graphene oxide (RGO) and poly(ethylene glycol)/RGO (PEG/RGO), were investigated in the formations of graphene coatings on polylactide granules and subsequent melt-processed nanocomposites. It is found that RGO nanosheets have good interfacial compatibility to form better coatings on polylactide granules. Melt processing of graphene-coated granules produced polylactide/graphene nanocomposites with higher mechanical strengths. Nanocomposite materials containing 0.1% RGO showed the best improvements of mechanical and thermal properties. As-prepared nanomaterials and nanocomposites were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-Vis), attenuated total reflectance infrared spectroscopy (ATR-FTIR), tensile, flexural and impact measurements, differential scanning calorimetry (DSC) and integrated thermogravimetric analysis (TGA-DTA). In general, the innovative strategy of aqueous spray coating and melt processing is applicable for manufacturing biodegradable PLA/graphene nanocomposites in the sustainable trend of environmentally friendly development. [ABSTRACT FROM AUTHOR]

The rising concern of environmental issues from the non-degradable conventional polymers is triggering the development of sustainable and renewable polymers. Thermoplastic starch (TPS) has been known to have huge potential to substitute conventional synthetic polymers. A thermoplastic starch was prepared using a non-food bitter cassava starch with isosorbide as plasticizer. To improve the dispersion and interfacial affinity of thermoplastic starch and boost the compatibility between starch and isosorbide, citric acid (CA) was used as an additive. The influence of citric acid to the TPS was then investigated. The result shows that citric acid improved tensile strength from 8.68 MPa to 11.98 MPa. The addition of citric acid at a concentration of 1 – 10 wt % can increase glass transition temperature (Tg) from 48.81°C to 63.89°C and storage modulus at 25°C from 1.20 GPa to 3.47 GPa. Two degradation temperatures (Td) were detected which are Td1onset value was decrease from 83.32°C down to 79.78°C while Td2onset value was decrease from 275.29°C down to 247.17°C and Td2max from 311.12°C to 295.06°C. [ABSTRACT FROM AUTHOR]

Schematic for the preparation of the PLA/CCPU blend films.

Olive pulp, which is formed 80% in the olive oil extraction process, attracts the attention of researchers with the zero waste project in Turkey. Our study aims to prove that olive pulp is not only a waste and can be used as a resource when used correctly as a filler in composite materials to provide not only durable but also shorter biodegradation times for polymer-based composite materials. The surface modification process with 3 different silanes containing epoxy, vinyl, and amino groups was applied to the surface of olive pulp (OP) to solve the problem of surface incompatibility with eco-grade thermoplastic polyurethane (TPU) matrix. The oil portion of OP was removed before silane treatments. Surface functions and thermal properties of both modified and unmodified OP powder samples were evaluated by FTIR, SEM, and TGA techniques, respectively. TPU/OP composites were fabricated using melt-compounding process, and mechanical, thermomechanical, thermal, melt flow, wear, biodegradation, and morphological properties of composites were reported. According to test results, TPU/VS-OP (vinyl silanized olive pulp) composite showed the highest hardness and wear resistance values among all composites. Additionally, silane modifications led to remarkable improvements for mechanical, thermal, thermomechanical, and melt flow properties of composites thanks to the enhancement of compatibility and interface adhesion between OP and TPU phases. It seems that VS-OP containing composite sample displayed the highest results in most of the examined results. It has been shown that the addition of unmodified and modified OP filler to TPU caused to level of the biodegradation of pure TPU, and as a result, environmentally friendly composites have been produced. [ABSTRACT FROM AUTHOR]

Graphene-related materials (GRM) are promising materials to improve mechanical, electrical, and optical polymer properties. Adding multi-wall carbon nanotubes (MWCNT) on GRM nanocomposites promotes synergistic effects on its electrical properties and electromagnetic interference shielding effectiveness (EMI SE). This study focused on evaluating the addition of MWCNT on three different polycarbonate (PC)/acrylonitrile butadiene styrene (ABS)/GRM nanocomposites. These hybrid nanocomposites were prepared by melt mixing using extrusion and injection-mold processes. The morphologies of the nanocomposites were evaluated by field emission gun scanning electron microscopy (FEG-SEM), and their proprieties were characterized by X-ray diffraction (XRD), oscillatory rheological, dielectric spectroscopy, and EMI SE analyses. The electrical behavior of all hybrid nanocomposites was anisotropic due to the injection-molded preparation process. The lateral size, thickness, and production method of the GRM were indicated to be critical factors for the electrical and EMI SE behaviors of these composites. The nanocomposites with GRM2, which had the smallest lateral size and thickness (graphene nanoplatelets), promoted total attenuation levels around 20 dB with 1.5 wt% of MWCNT, matching the EMI SE required for some commercial applications. Graphical Abstract [ABSTRACT FROM AUTHOR]

Biodegradable products are considered as an important solution in reducing the waste generated by the use of synthetic polymers. Thermoplastic starch (TPS) stands out with its success and low cost in the preparation of biodegradable products. In order to improve the low mechanical and physical properties of biodegradable polymeric products, morphology in co-continuous form was chosen as the target of our study as a promising solution. For this purpose, thermoplastic starch samples were prepared by melt processing method using starch and various plasticizers. TPS samples were examined from the perspective of morphological, rheological and thermal properties. Based on the obtained results, suitable TPS was determined that will allow obtaining the co-continuous morphology in the polymer blends to be prepared with polyethylene (PE). Polymer blends were prepared by melt processing method so that the selected TPS sample and PE were in different compositions. TPS/PE polymer blends were examined in terms of mechanical, rheological, morphological and thermal properties, and the most appropriate methods and parameters were determined for the preparation of samples with high TPS composition and co-continuous phase morphology. [ABSTRACT FROM AUTHOR]

Conductive polymer composites (CPCs) have been identified as viable replacements for graphite and metals for polymer electrolyte membrane fuel cell (PEMFC) bipolar plates (BPs). One important factor, apart from composite formulation, that affects the quality and properties of CPC BPs is the processing route. Therefore, understanding the possible processing methods for different matrix–filler combinations and their effects on the quality and properties of the plates can help in controlling and improving the final performance of BPs. This paper reviews the blending and molding techniques for CPC BPs, with a focus on relationship between formulation and processing method. The effects of processing route and conditions on microstructural features of CPC BPs, which affect the performance of the plates are also discussed. Finally, directions for further studies with potential to advance the development of quality and high‐performance CPC BPs are highlighted. Identified key areas for further research include control of filler orientation to improve through‐plane conductivity, correlation between processing parameters and dimensional accuracy of molded plates, and additive manufacturing of composite BPs. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) is one of the most versatile polymers widely used in packaging, textiles, automotive, and electrical applications. Melt blending of PP with micro- and/or nano-fillers is a common approach for obtaining specific end-use characteristics and major enhancements of properties. The study aims to develop high-performance composites by filling PP with CaSO4 β-anhydrite II (AII) issued from natural gypsum. The effects of the addition of up to 40 wt.% AII into PP matrix have been deeply evaluated in terms of morphology, mechanical and thermal properties. The PP–AII composites (without any modifier) as produced with internal mixers showed enhanced thermal stability and stiffness. At high filler loadings (40% AII), there was a significant decrease in tensile strength and impact resistance; therefore, custom formulations with special reactive modifiers/compatibilizers (PP functionalized/grafted with maleic anhydride (PP-g-MA) and zinc diacrylate (ZnDA)) were developed. The study revealed that the addition of only 2% ZnDA (able to induce ionomeric character) leads to PP–AII composites characterized by improved kinetics of crystallization, remarkable thermal stability, and enhanced mechanical properties, i.e., high tensile strength, rigidity, and even rise in impact resistance. The formation of Zn ionomers and dynamic ionic crosslinks, finer dispersion of AII microparticles, and better compatibility within the polyolefinic matrix allow us to explain the recorded increase in properties. Interestingly, the PP–AII composites also exhibited significant improvements in the elastic behavior under dynamic mechanical stress and of the heat deflection temperature (HDT), thus paving the way for engineering applications. Larger experimental trials have been conducted to produce the most promising composite materials by reactive extrusion (REx) on twin-screw extruders, while evaluating their performances through various methods of analysis and processing. [ABSTRACT FROM AUTHOR]

Summary: The present study aimed to produce polylactic acid (PLA) and ethyl cellulose (EC) biodegradable film using a single screw extruder and a roller mixer machine. This method resulted in better mixing of the polymers, reducing the possibility of burns and easier control of the film thickness. The mechanical properties measurement showed that tensile strength (TS) decreased by about 37.9%, and elongation at break (EAB) increased about 2.6‐fold by increasing EC to 75%. The increase in EAB indicated the plasticising effect of EC. Since flexibility is essential in shaping a material without fracture, PLA/EC blend films can be a good candidate for packaging. According to DSC results, glass‐transition temperature (Tg) decreased in the blend films, probably due to the increase in the hydrophilicity of the films after EC addition. The water contact angle of pure PLA film was about 83°, whereas it reached 28° in the film containing 75% EC. The water vapour permeability of PLA film was 2.24 × 10−11 g m.s.Pa−1 and PLA reduction to 25% increased the WVP by about two times. Adding EC into the pure PLA film reduced the transparency, indicating the potential of blend film for the packaging of light‐sensitive food products. Besides, EC addition enhanced PLA biodegradability after enzymatic treatment (alcalase) and soil burial. [ABSTRACT FROM AUTHOR]

The authors developed a nanocomposite using polypropylene (PP) and graphene nanoplatelets (GNPs) with a melt mixing method. Virgin PP was filled with three sets of GNPs with a fixed thickness (15 nm) and surface area (50–80 m2/g). The selected H-type GNPs had three different sizes of 5, 15 and 25 µm. The nanocomposites were made by loading GNPs at 1, 2 and 3 wt.%. Mechanical analysis was carried out by performing tensile, flexural and impact strength tests. The crystalline, micro-structural, thermal and dynamic mechanical properties were assessed through XRD, FESEM, PLM, DSC, TGA and DMA tests. It was observed that all three types of GNPs boosted the mechanical strength of the polymer composite. Increasing the nanofiller size decreased the tensile strength and the tensile modulus, increased the flexural strength and flexural modulus, and increased the impact strength. Maximum tensile strength (≈41.18 MPa) resulted for the composite consisting 3 wt.% H5, whereas maximum flexural (≈50.931 MPa) and impact (≈42.88 J/m) strengths were observed for nanocomposite holding 3 wt.% H25. Graphene induced the PP's crystalline phases and structure. An improvement in thermal stability was seen based on the results of onset degradation (TD) and melting (Tm) temperatures. Graphene increased the crystallization (Tc) temperatures, and acted like a nucleating agent. The experimental analysis indicated that the lateral size of graphene plays an important role for the nanocomposite's homogeneity. It was noted that the small-sized GNPs improved dispersion and decreased agglomeration. Thus overall, small-sized GNPs are preferable, and increasing the lateral size hardly establishes feasible characteristics in the nanocomposite. [ABSTRACT FROM AUTHOR]

This study aims to investigate changes in the structural properties of alkali/acid‐ultrasound modified Agave fibers and their performance immersed on a polyvinyl alcohol (PVA) matrix with plasticizer during melt mixing processing. Structural analysis revealed that ultrasound enhances the effectiveness of the conventional alkaline/acid treatments to modify fibers since the simultaneous treatment increased the partial removal of lignocellulosic components, water molecules, and amorphous regions which improved their processability on a PVA matrix. Specific energy consumption values indicated that during melt mixing the modified fibers required more energy to expose the chains of cellulose fraction to function as an interaction site for PVA chains. Once the mixture was homogenized, the fiber‐matrix interactions promoted high viscosity, friction, and mechanical stress in the chamber. Therefore, the modified fibers restricted the interaction between plasticizer and PVA in the obtained films, resulting in a highly structured, and reinforced network, increasing the storage modulus as dynamic mechanical analysis indicated. These findings highlight a feasible way to valorize Agave fibers and allow the understanding of the matrix‐fiber interactions during melt mixing processing, useful to predict the structural and mechanical properties of the films. [ABSTRACT FROM AUTHOR]

In this study, silane grafted and moisture cross-linked low density polyethylene nanocomposite foams were prepared by melt mixing and batch foaming process and the effects of silane content, nanoclay content, foaming agent concentration and clay type (clay modified with vinyltriethoxysilane (VTES) and amino-propyltriethoxysilane on foaming efficiency and foam properties were investigated. The morphology and the efficiency of silane modification of modified clay were characterized by series of tests, including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The results of Fourier transform infrared and thermogravimetric analysis showed that the silane modifiers were bonded to the surface of nanoclay through both physical and chemical bonds. According to XRD, these modifiers caused characteristic peak of clay to shift to lower angles, and make an increase in basal spacing. Gel content, density, scanning electron microscopy, compression, creep and rheological tests were used to determine the effect of different parameters on properties of cross-linked polyethylene foams. Results indicated that silane content has the significant effect on stress-strain behavior in compression mode. Compression set and creep deformation were affected by cell size and gel content. Furthermore, the rheological properties including complex viscosity, storage and loss modulus of unformed samples increased with the addition of silane and nanoclay content. [ABSTRACT FROM AUTHOR]

In recent years, significant attention has been given to "green" product innovation and related manufacturing processes. This work reports the preparation of few‐layer graphene (FLG) and respective PLA‐based composites by an eco‐friendly, efficient, and cost‐effective approach. FLG was produced in a scaled‐up process, based on the noncovalent functionalization of a micronized graphite with a pyrene derivate (PY), in aqueous solution. The exfoliation degree, morphology, and thermal stability of the exfoliated material were evaluated. Then, the influence of the pristine graphite and FLG on the morphology, crystallinity, thermal and mechanical properties of PLA composites produced by melt mixing is reported for the first time. The composites prepared with the lowest loading of 0.05 wt% demonstrated suitability for further processing for potential applications where product safety is crucial, such as in biomedicine. [ABSTRACT FROM AUTHOR]

Multi-walled WS2 nanotubes (NTs) with lengths ranging from 2 to 65 μm and widths from 50 to 110 nm were synthesized in a horizontal quartz-made reactor by a process yielding NTs with aspect ratios (ARs) between ∼40 and >1000. The NTs obtained were thermally stable in air up to 400 °C but were oxidized within the temperature range 400–550 °C to produce yellow WO3 particles. Critically, 400 °C is well above the temperature used to mix additives with the majority of melt-processable polymers. The hydrophilic WS2 NTs were easily dispersed in poly-(lactic) acid (PLA) using a twin-screw extruder, but the shear stresses applied during melt mixing resulted in chopping of the NTs such that the AR decreased by >95% and the tensile mechanical properties of the PLA were unchanged. Although the as-extruded unfilled PLA was >99% amorphous, the much-shortened WS2 NTs had a significant effect on the crystallization behavior of PLA, inducing heterogeneous nucleation, increasing the crystallization temperature (Tc) by ∼3 °C and the crystalline content by 15%, and significantly increasing the rate of PLA crystallization, producing smaller and more densely packed spherulites. The reduction in the AR and the nucleating effect of WS2 NTs for PLA are critical considerations in the preparation, by melt mixing, of composites of rigid 1D NTs and polymers, irrespective of the target application, including bone tissue engineering and bioresorbable vascular scaffolds. [ABSTRACT FROM AUTHOR]

In this study, eco-grade thermoplastic polyurethane (TPU), which includes 46% renewable content, was reinforced with date palm seed (DPS). Alkali and silane surface treatments were applied to DPS to increase the compatibility between DPS and TPU matrix. The oil of DPS was removed before treatments and surface functionalities of modified and pristine DPS samples were examined by Fourier transform infrared spectroscopy. Composites were fabricated using melt blending method and injection molding processes. Test samples of composites were characterized using tensile test, hardness test, water absorption study, dynamic mechanical analysis (DMA), melt flow index (MFI) test, thermogravimetric analysis, and scanning electron microscopy (SEM). According to test results, silane treatment led to remarkable improvement for mechanical performance of composites attributed to improvement of compatibility and interface adhesion between DPS and TPU. DMA results implied that higher storage modulus and glass transition temperature were achieved for treated DPS-containing composites compared to pristine DPS filled ones. Thermal stability of flexible segment of TPU increased with the addition of DPS regardless of surface treatment. Additionally, DPS loadings caused significant increase in MFI value of unfilled TPU. Silane-treated DPS-containing composite yielded the lowest water uptake value among samples due to the hydrophobicity of silane layer. Enrichment of interface adhesion of DPS to TPU matrix was confirmed by SEM micrographs of composites. Silane-treated DPS-containing composite displayed higher results among produced composites since the increase in interfacial interactions with TPU was achieved by silane treatment for DPS surface. [ABSTRACT FROM AUTHOR]

The influence of carbon nanotubes (CNTs) purity on the viscosity, thermal properties, impedance characteristics, and conductivity of CNT/low-density polyethylene (LDPE) nanocomposites was investigated. Two grades of CNT of similar aspect ratios but with different levels of carbon purities were investigated. CNTs with 90% ( C N T 90) and 95% ( C N T 95) carbon purity were used. The impedance analysis showed a lower electrical percolation threshold (EPT) of the C N T 90 / LDPE compared to the C N T 95 / LDPE. Also, at the same nanofiller loading, the characteristic frequency ( f c ) of the C N T 90 / LDPE composites was higher than that of the C N T 95 / LDPE composites. For example, at 7 wt% CNT, the f c of the C N T 90 / LDPE and C N T 95 / LDPE composites were 102 and 1.0 Hz, respectively. This finding reveals better dispersion of the C N T 90 compared to the C N T 95 in the LDPE. The better dispersion of CNT90 compared to CNT95 in the LDPE is supported by the processing behavior analysis that showed higher viscosity and mixing torque for the C N T 90 / LDPE composites compared to the C N T 95 / LDPE composites. [ABSTRACT FROM AUTHOR]

The acoustic melt stream velocity field, total force, and trajectory of fluorescent particles in the plasticizing chamber were analyzed using finite element simulation to investigate the acoustic streaming and mixing characteristics in ultrasonic plasticization micro-injection molding (UPMIM). The fluorescence intensity of ultrasonic plasticized samples containing thermoplastic polymer powders and fluorescent particles was used to determine the correlation between UPMIM process parameters and melt mixing characteristics. The results confirm that the acoustic streaming driven mixing occurs in ultrasonic plasticization and could provide similar shear stirring performance as the screw in traditional extrusion/injection molding. It was found that ultrasonic vibrations can cause several melt vortices to develop in the plasticizing chamber, with the melt rotating around the center of the vortex. With increasing ultrasonic amplitude, the melt stream velocity was shown to increase while retaining the trace, which could be altered by modulating other parameters. The fluorescent particles are subjected to a two-order-of-magnitude stronger Stokes drag force than the acoustic radiation force. The average fluorescence intensity was found to be adversely related to the distance from the sonotrodes' end surface, and fluorescence particles were more equally distributed at higher parameter levels. [ABSTRACT FROM AUTHOR]

The influence of polyethylene (PE) molecular structure on multi-walled carbon nanotubes (MWCNT)/PE composites processing behavior and their thermal, rheological and electrical properties were investigated. Two different types of PE of almost the same viscosity were investigated; namely, high-density polyethylene (HDPE) and low-density polyethylene (LDPE). Nanocomposites filled with up to 10 wt.% MWCNT were prepared by the conventional melt-mixing method. The MWCNT exhibited better dispersion in HDPE than in LDPE. The crystallinity of the HDPE marginally increased with the addition of the MWCNT, while no significant influence of the MWCNT on the LDPE crystallinity was observed. The AC electrical conductivity of both the HDPE and LDPE nanocomposites were almost the same. Thus, we concluded that there is no significant effect of the PE structure on the formation of the MWCNT networks. [ABSTRACT FROM AUTHOR]

The investigation of polypropylene (PP)/clay nanocomposites has received considerable scientific and technological attention during the last decades due to their good mechanical and barrier properties. In the present article, the effects of adding Cloisite15A (C15A) nanoclay in polypropylene (PP) were investigated. PP nanocomposites were prepared by a direct melt mixing method. For better dispersion of C15A, 30 wt% of nanoclay masterbatch was first prepared by melt mixing of PP matrix and acrylic acid grafted PP oligomer (PP- g -AA) in a compounder, before being used to produce nanocomposites with 2 and 5 wt% of C15A. The aim of this work was to used nanoclay filled nanocomposites with suitable properties for cable application like good flame-retardant property; improve dye-ability and resilience of polypropylene. The XRD results indicated an intercalated layer structure for nanocomposites, The SEM examination showed satisfactory dispersion of nanoclay in 2 wt% of C15A and some degree of agglomeration in 5 wt% of C15A. DSC analysis indicated that C15A acts as a nucleating agent and increases crystallinity in the nanocomposite. TGA showed with increasing nanoclay, heat resistance was improved and degradation temperatures increased. Limiting oxygen index (LOI) tests showed increased flame retardancy from 25% for neat polypropylene t0 32.2% for nanocomposites of 5 wt% of C15A. The tensile modulus was improved from 423 MPa for neat polypropylene to 474 MPa for nanocomposites with 5 wt% of C15A. This result indicates that increasing C15A content had a suitable effect on the tensile properties. Melt spinning investigation on low oriented yarn (LOY), draw textured yarn (DTY), and fully drawn yarn (FDY) of 2 wt% C15A nanocomposite showed a reduction of linear density for FDY and an increase of the shrinkage. Furthermore, the obtained results for the improvement of dye-ability and compression resilience showed that PP/C15A is appropriate for textile products. [ABSTRACT FROM AUTHOR]

In the present paper the effect of the diatomite, also known as diatomaceous earth and kiesel guhr (KG), content on mechanical, thermo-mechanical, melt-flow and thermal performance of thermoplastic polyurethane-based composites was investigated. Composites were fabricated by melt blending method with 10, 20, 30 and 40% filling ratios of KG. and injection molded test samples were characterized using tensile, hardness, dynamic mechanical analysis (DMA), melt flow index (MFI), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) analysis. According to test results, KG inclusions effect mechanical, thermal and morphological properties of composites positively up to 30% KG content. Further addition of KG caused remarkable reductions in related properties. Tensile strength of unfilled TPU exhibited increasing trend and elongation showed no obvious difference after KG loadings. TPU/KG composites yield relatively higher MFI values with respect to unfilled TPU. Glass transition temperature of TPU shifted to 6 points higher value by the help of KG incorporation. TGA findings revealed that KG additions caused improvement for thermal stability of TPU. Homogeneous dispersion of KG particles for their lower content, whereas agglomorate formations for higher loading level of KG were confirmed by SEM micrographs. TPU composite containing 10% KG showed the highest results among samples.

The authors developed a nanocomposite using polypropylene (PP) and graphene nanoplatelets (GNPs) with a melt mixing method. Virgin PP was filled with three sets of GNPs with a fixed thickness (15 nm) and surface area (50–80 m2/g). The selected H-type GNPs had three different sizes of 5, 15 and 25 µm. The nanocomposites were made by loading GNPs at 1, 2 and 3 wt.%. Mechanical analysis was carried out by performing tensile, flexural and impact strength tests. The crystalline, micro-structural, thermal and dynamic mechanical properties were assessed through XRD, FESEM, PLM, DSC, TGA and DMA tests. It was observed that all three types of GNPs boosted the mechanical strength of the polymer composite. Increasing the nanofiller size decreased the tensile strength and the tensile modulus, increased the flexural strength and flexural modulus, and increased the impact strength. Maximum tensile strength (≈41.18 MPa) resulted for the composite consisting 3 wt.% H5, whereas maximum flexural (≈50.931 MPa) and impact (≈42.88 J/m) strengths were observed for nanocomposite holding 3 wt.% H25. Graphene induced the PP’s crystalline phases and structure. An improvement in thermal stability was seen based on the results of onset degradation (TD) and melting (Tm) temperatures. Graphene increased the crystallization (Tc) temperatures, and acted like a nucleating agent. The experimental analysis indicated that the lateral size of graphene plays an important role for the nanocomposite’s homogeneity. It was noted that the small-sized GNPs improved dispersion and decreased agglomeration. Thus overall, small-sized GNPs are preferable, and increasing the lateral size hardly establishes feasible characteristics in the nanocomposite.

The aim of this present work was to study the applicability of waste marble dust (MD) in poly(lactic acid) (PLA)-based composites. Samples containing up to 20 wt% waste MD were prepared via melt blending. The attention was focused on the investigation of mechanical, morphological, thermal properties and the wear resistance of the PLA/MD composites. Regarding the mechanical properties, both the tensile and the flexural modulus improved remarkably, however, a slight loss was observed in strength and deformability. The impact toughness showed an increasing tendency up to 10 wt% MD loading, which was followed by a marginal decrease at higher concentration. With respect to the sliding wear rate, the composite with the highest MD content showed the best wear resistance. According to the DSC measurements, the MD hampered the chain mobility of PLA, thereby reducing the crystalline ratio. Overall, composites with improved properties were developed, while the reuse of waste MD is expected to reduce the production costs as well. [ABSTRACT FROM AUTHOR]

The effects of adding nanoclay to improve the thermal and mechanical properties of polypropylene (PP) copolymers grade (EPD60R) used in the pipe industry were investigated. To improve the dispersion of the nanoclay in the polymeric matrix, a 30 wt% of nanoclay master batch was first prepared by mixing PP matrix maleic anhydride PP oligomer (PP-g-MA) and Cloisite® 15A (C15A) nanoclay. The prepared master batch was used to produce nanocomposites with 2 and 5 wt% nanoclay. The nanocomposites were analyzed by XRD (X-ray diffraction), SEM (Scanning electron microscopy), DSC (Differential scanning calorimetry), TGA (Thermogravimetric analysis), and other mechanical tests. The XRD and SEM results indicated the occurrence of an intercalated layer structure in the nanocomposites. Thermal properties of the nanocomposites were investigated using DSC and TGA tests. The crystallinity of the 2 wt% nanoclay was improved by about 59.23% in the nanoclay reinforced samples. As the content of nanoclay increased, the composite exhibited higher thermal degradation temperature. Performing a limiting oxygen index (LOI) test on the samples showed that the addition of nanoclay to the EPD60R matrix increased the flame retardancy by 12.58%. The tensile modulus of the nanocomposites was improved compared to the pure polymer, while the elongation at break and at yield showed a reduction. To investigate the nanocomposite in pipe application, a pipe (external diameter 110.8 and thickness 3.65 mm) was manufactured in a special tube extruder machine with 2 wt% of C15A. Tests of the tube’s physical and mechanical properties indicated that its ring stiffness increased by 25% compared to the pure PP.

In this work, a novel melt mixing method and its corresponding mixing device are developed. The extensional/shear strength ratio of the device can be controlled by adjusting its eccentricity. The structure and working principle of the device are introduced in detail. Carbon fiber (CF)/polyamide 6 (PA6) composites are prepared via this novel mixing device. The influences of eccentricity and mixing time on the morphology, CF length, thermal, mechanical, and electrical properties of CF/PA6 composites are studied. Scanning electron microscopy results show that CFs uniformly disperse in the matrix and interfacial adhesion between CFs and PA6 is improved. It is observed that CF length and its distributions can be optimized by changing eccentricity. The maximum average fiber length is about 351 μm. Differential scanning calorimetry results exhibit that the Xc increases 6.5% when eccentricity is 2 mm. Mechanical test results show tensile strength and modulus increase first and then decrease with the increasing eccentricities or mixing time. Electrical property measurement shows an obvious increase when eccentricity is 2 mm due to good fiber dispersion and long fiber retention length. The experimental results indicate that the novel mixing method and its corresponding apparatus provide an environment‐friendly and effective way to prepare polymer‐based composites. [ABSTRACT FROM AUTHOR]

This investigation reports the preparation and properties of thermoplastic polyurethane/silica nanocomposite prepared via melt mixing process. In this case, nanosilica at different loading was mixed with a polyester-based thermoplastic polyurethane (TPU). The dispersion of nanofiller was studied by the SEM and TEM analyses. The nanocomposite with optimal dispersion of nanofiller has better filler-polymer interaction that has been confirmed by the FT-IR study. TPU with 1 phr of nanosilica loading showed better tensile properties. DSC study revealed that incorporation of fumed silica in the TPU matrix does not substantially affect the refinement of TPU crystallite, and thus resulted in an insignificant change in glass transition temperature (Tg) and crystalline melting temperature of the nanocomposite. TGA study also confirmed enhanced onset degradation temperature and maximum degradation temperature (Tmax) for optimal nanosilica composite. The final degradation temperature and char content also increased with an increase in fumed silica content. Water contact angle (WCA) study revealed that hydrophilicity of the nanocomposite increased with the incorporation of fumed silica. [ABSTRACT FROM AUTHOR]

The Swartoup and Polisiehoek plutons in the Swartoup Hills (South Africa) formed during an episode of significant magma emplacement in the Mesoproterozoic Namaqua Sector of the Namaqua Metamorphic Province. They intruded into mid-crustal metasedimentary rocks of the metapelitic Koenap and mafic to carbonate-bearing Bysteek Formations during and shortly after the ∼1,200–1,220 Ma regional metamorphic peak that reached ultrahigh temperatures. Subsequent to pluton emplacement, the crust underwent regional high-temperature deformation during slow near-isobaric cooling. A further episode of pluton emplacement associated with fluid circulation truncated the first-order regional tectonic structures at ∼1,100 Ma. Based on their petrography, the Swartoup pluton is subdivided into leuco-granitoids with biotite as the sole mafic phase, pyroxene granitoids, and garnet-bearing granitoids, which may contain significant biotite. These subgroups display distinctive geochemical variations from one another, and from the Koenap Formation migmatites and the Polisiehoek granites, which are exposed nearby. Incompatible trace element distributions suggest that the Swartoup and Polisiehoek granitoids represent modified A-type granite magma, consistent with derivation from partial melting of quartzo-feldspathic crust. The magmas incorporated significant amounts of juvenile mantle-derived magma (εNd1200 of ∼−5, and LREE-depleted), but do not require older, early to late Paleoproterozoic crust. Particularly close to contacts to the calcic Bysteek Formation, localized contamination of the Swartoup granites by supracrustal carbonates is evident. A relatively pervasive alkali metasomatic effect is manifested strongly in the initial 87Sr/86Sr and LILE profiles of the Polisiehoek granites in particular, as well as in some of the Swartoup pyroxene granitoids, which could be either a symptom of CO2 metasomatism related to the Bysteek Formation carbonates, or to post-magmatic fluid metasomatism, perhaps linked to regional shearing. The comparison of our results with literature data suggests that similar sources, A-type granitic, Meso- to Paleoproterozoic crustal, and enriched mantle, have contributed, in locally differing proportions, to granites in most parts of the Namaqua Sector. Most likely, these plutons were generated during crustal and mantle melting in a long-lived hot continental back-arc environment.

This paper investigates the structure-property-processing correlations of electrically conductive polypropylene (PP) nanocomposites. The process parameters and fabrication techniques of PP-based composite materials were studied. Various structures of carbon allotrope-based materials, including synthetic graphite (SG), exfoliated graphene nanoplatelets (xGnP), multi-walled carbon nanotubes (MWCNTs) and carbon black (CB), were used to fabricate the PP-based nanocomposites. The nanocomposites were prepared by either direct melt mixing using an internal mixer or by ball milling of components before the melt mixing process. The electrical and flexural properties were measured. In order to understand the conductivity behavior, both in-plane and through-plane electrical conductivities were measured. The results showed that the incorporation of the xGnP into PP/60 wt.% SG composites resulted in a slight increase of the in-plane conductivities and had a minimal effect on the through-plane conductivities. The addition of MWCNTs and CB to the PP/SG/xGnP composites had a significant effect on the electrical properties and was more pronounced in the case of MWCNTs. The flexural properties of all samples were much lower than those of pure PP. The interface between the filler and the PP matrix and the morphology of the composite materials were observed from the fracture surfaces of the composites using scanning electron microscopy (SEM). In addition, SEM was employed to observe adhesion, microstructural homogeneity, orientation of the xGnP platelets and agglomeration in the composites.

In recent years, polymer matrix nanocomposites production and usage ratio is increased and therwithal the applicability of these composites to other areas has also improved significantly. Textile industry is one of these areas. With the used of polymer matrix nanocomposites in textile applications, it become possible to produced improved products with high strength, functional, antibacterial and good mechanical properties. Textile recycling yarns get popular day by day. Lots of textile company producing recycled PET fiber yarns and this is contributed to the environment. In this study recycled PET polymer was used as a matrix and enriched nanoparticles to investigate mechanic, microstructure and thermal properties. Melting method was used for producing of nanocomposite multifilament yarns. Filament thickness was 120 nm and TiO2, ZnO and CNT was used as a reinforcement to ratio %0.1, %0.3, %0.5 respectively. After analysis and experiments, it was seen clearly reinforcements was affected positively the mechnanical, microstructure and thermal properties of r-PET nanocomposites. According to the result of tensile strength tests, it was seen that CNT reinforcement increased tensile strength of r-PET polymer about %15. [ABSTRACT FROM AUTHOR]

Poly(propylene carbonate) (PPC) is an aliphatic polycarbonate synthesized from carbon dioxide and propylene oxide. Poly(3‐hydroxybutyrate) (PHB) is a type of thermoplastic polyester produced by biological fermentation. The blending of PHB with PPC can effectively enhance the mechanical properties and barrier properties of PPC. Bionanocomposites of PPC/PHB enhanced by cellulose nanocrystal (CNC) are prepared via a two‐step process using polyethylene glycol as a carrier. Results show that the oxygen barrier properties of the composites increased with the increase of the CNC content. When the CNC content is 1 wt%, the oxygen barrier performance increases nearly 18 times. The assumed model can predict the barrier performance of composites with the combined influence of morphology and CNC distribution. This will make PPC/PHB/CNC nanocomposites a very promising degradable material for food packaging application. [ABSTRACT FROM AUTHOR]

Widespread attention to make use of biodegradable resources as a replacement for petroleum products leads to the exploitation of natural fiber reinforced composites. Natural fiber reinforced polymer composites usually exhibit lower mechanical properties than synthetic fiber ones. Thus, understanding key factors affecting the overall mechanical properties in order to increase them is crucial. One underlying factor is the length of fiber highly contributing to the extent of matrix/fiber interfacial load transfer at the interface. However, the concurrent examination of the load transfer mechanism at the interface of fiber/matrix in terms of fiber length has not been well performed using computational, analytical and experimental approaches. This work is aimed at the determination of the critical fiber length associated with a full load transfer condition using various methods to better understand their accuracy and the interfacial load transfer mechanism. For this purpose, specimens of neat polypropylene (PP) and 20 wt% kenaf/PP composites were fabricated using extrusion injection molding. Tensile testing, scanning electron microscopy and density measurements were conducted to incorporate the obtained results into the models and to verify the results predicted by the models. A three dimensional representative volume element (RVE) representing the filler content of fabricated specimens was assumed. A micromechanical model was employed to make the results of analysis independent of the RVE dimensions. The critical fiber length for a full load transfer was determined by evaluating the stored elastic strain energy changes against the fiber length. The results showed that the kenaf fiber length is critical to both the load transfer efficiency and stiffening of composites. The results further revealed that to obtain the full interfacial load transfer, the length of kenaf fibers needs to be greater than the critical length being ∼2.4 mm provided that perfect kenaf/PP interfacial interaction exists. [ABSTRACT FROM AUTHOR]

The present research aimed to investigate the influence of Zr-based metal-organic framework, i.e. UiO-66, on the performance of poly(ethylene terephthalate) (PET) by the melt mixing method. PET/UiO-66 nanocomposites were prepared at 0.25, 0.5, 1, and 2 wt% of UiO-66. FESEM microphotographs showed the success of the melt mixing method in the fine dispersion of UiO-66 within PET. Additionally, XRD patterns confirmed that UiO-66 retained its structure after melt mixing at 260 ° C. DSC analysis suggested that UiO-66 acted as a nucleating agent with a best performance at 1 wt% loading, i.e. 45 % decrease in the crystallization half-time and 11 % increase in the crystallization temperature. Furthermore, the PET/UiO-66 nanocomposites exhibited an improvement in char formation and resistance to complete thermal degradation at high temperatures compared to neat PET. The inclusion of UiO-66 in PET increased the impact strength with a maximum value at 0.5 wt% loading, e.g. more than twice neat PET. In addition, DMTA results indicated that UiO-66 acted as a strengthening agent in PET. Rheological investigations revealed that PET/UiO-66 exhibits the non-Einstein-like viscosity behavior in which the complex viscosity decreased by increasing UiO-66 content. We reasoned that behavior mainly to the flexible nature of the UiO-66 particles. Although all the samples showed almost Newtonian behavior at 260 ° C in frequencies between 0.03 Hz and 100 Hz, PET/UiO-66 (0.5) presented the shear thinning behavior. This was ascribed to the good dispersion with the strong interfacial interaction, leading to a microstructure with yield stress. [Display omitted] • PET/UiO-66 nanocomposites were prepared via the melt mixing method. • UiO-66 acted as a nucleating agent with a best performance at 1 wt%. • The inclusion of UiO-66 increased the impact strength with a maximum value at 0.5 wt%. • UiO-66 acted as a strengthening agent in PET. • The complex viscosity of PET decreased steadily with the addition of UiO-66. [ABSTRACT FROM AUTHOR]

The purpose of this study is to fabricate highly dispersed powder suitable for spheroidization with further application in additive technologies. The volumetric reduction of the FeCl2–CaCl2 melt by calcium dissolved in CaCl2 produced a fine iron powder. The process included three states, notably, the preparation of melts containing FeCl2 and Ca, their mixing, and high-temperature aging at 800°C for 1 h. Upon finishing the process, the solidified fusion cake is divided into top and bottom parts. The product from the top part has a specific surface of 7.60 m2/g, and that from the bottom part has a specific surface of 5.38 m2/g. The average particle size is 157 μm for the former and 124 μm for the latter. Ultrasonic dispersing is reduced to 26 μm and 71 μm, respectively. Quantitative X-ray phase analysis shows that the main phase of powder is metallic iron (more than 97 wt %). Thus, the originality of the research is due to the application of an intense volumetric reduction of iron from chloride melts by calcium dissolved in its chloride. The uniqueness of the study is due to its product, so far as the main part of reduced iron is arranged in the melt bulk in the form of linear aggregates 40–600 μm in length and 10–50 μm in diameter, which easily destruct by ultrasonic dispersal into separate crystals with an average size of 26 μm. The results of the study show the possibility of implementing the calcium-thermal production of fine iron powder. [ABSTRACT FROM AUTHOR]

In this study, active biocomposite films of low-density polyethylene (LDPE) containing 5% wt. of curcumin, a natural chemical produced by some plants, are developed by melt extrusion and hot pressing. The detailed study of the physicochemical properties of the formed films demonstrates that the curcumin molecules, homogeneously dispersed in the whole volume of the LDPE matrix, cause a notable increase in the thermal stability of the LDPE polymer, without altering its thermal processability. At the same time the LDPE's water vapor barrier properties are significantly improved, while an effective antioxidant scavenging activity is observed against the 2,2-diphenyl-1-picrylhydrazyl free radicals (DPPH•). These results indicate that the developed active films based on the combination of LDPE and curcumin, following industrially applied preparation methods, are ideal candidates for active food packaging applications. Image 1 • Highly antioxidant food packaging films from low-density polyethylene (LDPE) and curcumin. • Excellent water vapor barrier properties. • High thermal stability without altering thermal processability. • Fabrication through industrially applicable methods. [ABSTRACT FROM AUTHOR]

Carbon black (CB)-filled polylactic acid (PLA) composites attract a significant interest due to their superior structural and functional performances. Properties of CB-filled PLA composites depend on physical and chemical interactions in them. In this study, interactions within CB (N220)-filled PLA composites as a function of processing method, filler concentration, and their effect on mechanical properties are investigated via mechanical tests. Strong interface interaction at intermediate concentration of 2.5 wt.% CB with PLA was confirmed through mechanical tests. Moreover, a 2.5 wt.% of CB-formed networks within PLA composites, which added the fracture resistance in the weaker phase, thereby improving their mechanical properties. Beyond 2.5 wt.%, a linked skeletal grid was formed, enhancing the fracture path in a weaker phase and deteriorating the mechanical properties. Experimental results on density and elastic modulus were compared with the theoretical model predictions. This study gives an insight on interactions controlling physical and mechanical properties related to various processing techniques and weight percent of CB in PLA composites. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) composites including various amounts of silica aerogel (SA) microparticles were prepared by melt mixing in an internal mixer. The morphology and microstructure of the prepared composites were investigated by scanning electron microscopy (SEM). Mechanical properties of the samples, including elastic modulus, tensile stress, elongation and stress at break, were measured by tensile tests. In addition, the other mechanical features, including Izod impact strength, hardness and wear resistance, were evaluated and then related to the structure of the PP/SA composites. Furthermore, the thermal characteristics of the composites, such as heat deflection temperature and thermal stability, were studied by thermal gravimetric analysis (TGA). The SEM photographs indicated the satisfactory SA particles dispersion for the compositions of 1% and 3% but agglomeration of the aerogels at higher SA contents. Since the composites became stiffer, the impact and tensile strength decreased. The addition of the SA to the PP matrix yielded harder samples with lower weight loss and coefficients of friction in wear tests. The TGA evaluations confirmed that the presence of SA promoted and upgraded the thermal stability and heat deflection temperature of PP. The thermal results proved the superior potential of PP as an insulator when the SA particles were added. [ABSTRACT FROM AUTHOR]

Co-continuous blend systems of polycarbonate (PC), poly(styrene-co-acrylonitrile) (SAN), commercial non-functionalized multi-walled carbon nanotubes (MWCNTs) or various types of commercial and laboratory functionalized single-walled carbon nanotubes (SWCNTs), and a reactive component (RC, N-phenylmaleimide styrene maleic anhydride copolymer) were melt compounded in one step in a microcompounder. The blend system is immiscible, while the RC is miscible with SAN and contains maleic anhydride groups that have the potential to reactively couple with functional groups on the surface of the nanotubes. The influence of the RC on the localization of MWCNTs and SWCNTs (0.5 wt.%) was investigated by transmission electron microscopy (TEM) and energy-filtered TEM. In PC/SAN blends without RC, MWCNTs are localized in the PC component. In contrast, in PC/SAN-RC, the MWCNTs localize in the SAN-RC component, depending on the RC concentration. By adjusting the MWCNT/RC ratio, the localization of the MWCNTs can be tuned. The SWCNTs behave differently compared to the MWCNTs in PC/SAN-RC blends and their localization occurs either only in the PC or in both blend components, depending on the type of the SWCNTs. CNT defect concentration and surface functionalities seem to be responsible for the localization differences.

Flexible thermoelectric materials are prepared by melt mixing technique, which can be easily scaled up to industrial level. Hybrid filler systems of carbon nanotubes (CNTs) and copper oxide (CuO), which are environmental friendly materials and contain abundant earth elements, are melt mixed into a thermoplastic matrix, namely polypropylene (PP). With the CNT addition, an electrical network could be built up inside the insulating PP for effective charge transport. The effect of CuO addition is determined by the corresponding CNT concentration. At high CNT concentration, largely above the percolation threshold (φc, ca. 0.1 wt%), the change in the TE properties is small. In contrast, at CNT concentration close to φc, the co-addition of CuO could simultaneously increase the electrical conductivity and Seebeck coefficient. With 5 wt% CuO and 0.8 wt% CNTs where a loose percolated network is formed, the Seebeck coefficient was increased from 34.1 µV/K to 45 µV/K while the electrical conductivity was from 1.6 × 10−3 S/cm to 3.8 × 10−3 S/cm, leading to a power factor of 9.6 × 10−4 µW/mK2 (cf. 1.8 × 10−4 µW/mK2 for the composite with only 0.8 wt% CNTs).