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This paper aims to develop sustainable geopolymer composites reinforced with silverskin fibers derived from coffee industry waste. Geopolymer and geopolymer composites were synthesized from blast furnace slags (BFS) with a solid/liquid (alkaline solution) ratio of 1.4. A sodium metasilicate/sodium hydroxide (Na2SiO3/NaOH) mixture at a mass ratio of 2.5 served as the alkaline activator in the geopolymerization process. The composites were evaluated by incorporating 2%, 3%, and 5% by weight of silverskin fibers, which were used in their natural form (SGCn), after treatment with sodium hydroxide (SGCNaOH), and after treatment with sodium hydroxide followed by a steam explosion process (SGCSE).Characterizations of the geopolymer composites included X-ray fluorescence analysis (XRF) for elemental oxide identification, Fourier transform infrared spectroscopy (FTIR) for functional group detection, and thermogravimetric analysis (TGA) for thermal stability assessment. The influence of fibers on the hardness of the geopolymer materials was evaluated using hardness scale measurements. Morphologies, microstructures, and elemental compositions were analyzed through field emission gun scanning electron microscopy with energy dispersive X-ray spectroscopy (FEG-SEM/EDS).The results demonstrate that the incorporation of silverskin fibers, especially those treated with NaOH and subjected to steam explosion, significantly enhances the thermal stability of geopolymer composites. The 5% NaOH-treated fiber composite exhibited the highest Tmax and Tend, indicating superior thermal stability. Additionally, the 5% SGCNaOH composite showed the highest residual mass, further supporting the enhanced thermal stability of these composites.Unlike other fibers, which showed a decrease in hardness, the addition of SGCSE fibers maintains a relatively high hardness in the geopolymer composites. The 2% SGCSE composite exhibited an average hardness equal to that of the pure geopolymer at 66 Shore D.These findings underscore the potential of using treated silverskin fibers to develop more thermally stable, cost-effective, and sustainable geopolymer materials. By utilizing industrial residues and waste, these advanced materials can be applied in the production of construction and building materials, contributing to both environmental sustainability and economic efficiency.

Fluorene-benzothiadiazole (PFBT), commercially known as F8BT, and fluorene-thiophene (PFT) copolymers were synthesized by the Suzuki-Miyaura coupling polycondensation technique in the presence of a phase transfer catalyst (Aliquat 336). These novel copolymers showed higher molar masses, lower dispersivity, and thermal stability above 400 °C when synthesized under the modified (M) action of Aliquat 336 (F8BT-M). Polymer Light-emitting diodes (PLEDs) were assembled with the novel synthesized copolymers as the emitter layer. For F8BT-M, a maximum luminance of 327 cd/m2 was achieved, while a diode containing just the commercial F8BT resulted in only 210 cd/m2. As for the PFT copolymers, it was observed that for the Aliquat 336 sample synthesized in a 60h extended (E) (PFT-ME), the luminance of the PLED was much higher than that where the reaction time was 48 h (PFT-M), with a luminance of 168 cd/m2 and 54 cd/m2, respectively. Without Aliquat 336, the PFT copolymer did not show an electroluminescent signal. The improved electroluminescence in the copolymers with Aliquat 336 was attributed to the improved synthesis conditions, i.e., reaction time and catalytic system employed. The results suggest that copolymers with luminescent and morphological properties, more suitable for light-emitting devices, might be obtained with simple modifications during synthetic polycondensation reactions.

Thermoelectric materials have been the object of interest in energy demand, given their potential for heat capture and the possibility of conversion into electricity. Among the possible thermoelectric materials, polymeric ones have been investigated because they are durable, non-toxic, and reproducible. This work used polyaniline (PANI), a good conductivity polymer, as a matrix to prepare hybrid nanocomposites. Nanoparticles were incorporated into the PANI matrix via solution with m-cresol. Two types of novel nanoparticles were used: zinc oxide (ZnO) synthesized with morphologies of nanoneedles (n-ZnO) and nanoflowers (f-ZnO). Hybrids of graphene oxide (GO) and ZnO with these morphologies (GO/n–ZnO and GO/f–ZnO) were incorporated into the hybrid PANI nanocomposites. Thermal stability was evaluated by thermogravimetric analysis (TGA). An improvement in thermal stability was observed with increasing GO/ZnO nanoparticles, as well as a higher degradation of the polymer matrix for higher levels of ZnO nanoparticles. The absorption bands of nanoparticles and PANI were observed by Fourier infrared spectroscopy (FT-IR). The corresponding characteristic bands of the functional groups were well evidenced, reflecting the success in synthesizing thermoelectric nanocomposites. Those with hybrid nanoparticles (GO/ZnO) had higher values of electrical conductivity (10.8 and 10.5 S cm−1), while those with only ZnO nanoparticles had higher Seebeck coefficient values (166.4 and 67.4 μV K−1). The only one with the highest thermoelectric force factor was PANI/GO/n-ZnO, with a value of 14.79 μW m−1 K−2, which is 49.3 times greater than the pure polymer and 1.5 times greater than the PANI/n-ZnO nanocomposite.

A suspended particle device (SPD) is a type of smart window that can be switched with an electrical stimulus, and its transmittance varies proportionally with the applied voltage. This work presents a new route to produce SPD, using hydrogels based on conventional polymers with trapped reduced graphite oxide (rGO) micrometric particles as an active layer, to make this product more accessible, as it is not yet cost-effective. The trapped rGO particles were produced from the chemical oxidation of graphite, followed by thermal reduction. The results of X-ray photoelectron spectroscopy (XPS) confirmed the production of reduced graphite oxide particles with a low quantity of oxidized carbon groups. X-ray diffraction (XRD) showed the crystalline graphitic structure of the produced rGO particles and proved their incorporation inside the hydrogel's tridimensional polymeric network. The presence of these particles causes a decrease of 28.3% in the degree of swelling of the hydrogel. The devices were assembled in two different configurations: (i) fluorine-doped tin oxide (cFTO); and (ii) silver paint (cAg) by changing the positions of the electrodes. The cAg device displayed better responses, with an immediate increase of 38.6% in transmittance, due to an applied voltage of 220 V, compared to the switched-off device. The voltage applying time also increased the transmittance of the cAg device, with an increase of 36.6% after 20 min under 220 V, compared to the device immediately turned on.

With its extensive production and consumption, the coffee industry generates significant amounts of lignocellulosic waste. This waste, primarily comprising coffee biomasses, is a potential source of cellulose. This cellulose can be extracted and utilized as a reinforcing agent in various biocomposites with polymer matrices, thereby creating high-value products. One such biodegradable polymer, Poly(butylene adipate-co-terephthalate) (PBAT), is notable for its properties that are comparable with low-density polyethylene, making it an excellent candidate for packaging applications. However, the wider adoption of PBAT is hindered by its relatively high cost and lower thermomechanical properties compared with conventional, non-biodegradable polymers. By reinforcing PBAT-based biocomposites with cellulose, it is possible to enhance their thermomechanical strength, as well as improve their water vapor and oxygen barrier capabilities, surpassing those of pure PBAT. Consequently, this study aims to provide a comprehensive review of the latest processing techniques for deriving cellulose from the coffee industry’s lignocellulosic by-products and other coffee-related agro-industrial wastes. It also focuses on the preparation and characterization of cellulose-reinforced PBAT biocomposites.

Novel nanocomposites of polyamide-11 (PA11) reinforced with commercial graphene nanoplatelets (GNP) in amounts of 1.0, 2.5, and 5.0 wt.% were prepared and characterized for their thermal stability and aging performance. The processing of the nanocomposites was carried out by mixing PA11 in the molten state employing a double screw mini-extruder at 200 °C under 60 rpm screw speed, with a residence time of 7 min. The incorporation of GNP increased the thermal stability of PA11, particularly in the amount of 1.0 wt.%, as observed by thermogravimetric analysis. X-ray diffraction indicated that the composites' crystallinity increased with 1.0 and 2.5 wt.% of GNP. Evidence of agglomerates formation in the sample with 5.0 wt.% of GNP suggests it to be less dispersed in the PA11 matrix and associated with reduction in crystallinity. The dynamic mechanical analysis showed that GNP promoted an increase in the storage and loss moduli. The increase of GNP in the PA11 matrix enhanced the water contact angle and, therefore, provided greater hydrophilicity of the nanocomposite. The GNP reinforcement prevents the decrease in the molar mass of PA11, estimated by the corrected inherent viscosity (CIV) measured with aging time into water at 85 °C, when compared to the performance of neat PA11. All nanocomposites had CIV values above 1.20 dL/g before and after the aging test. Therefore, using the lowest GNP content of 1.0 wt.% proved to be the more efficient for application in flexible oil/gas pipelines.

A new technique based on the modified Hummer's method to synthesize reduced graphene oxide (rGO) with high purity, as well as enhanced quality and low layer stacking is presented. It aims to demystify traditional considerations made from X-ray diffraction by introducing comprehensive models to determine the number of stacked layers, as well as understand and respect the limit of the physical phenomenon involved in the technique. Poly (vinylidene fluoride) (PVDF) nanocomposites incorporated with up to 5.0 wt.% of rGO were processed via extrusion without using a compatibilizing agent. The results showed that the rGO nanoparticles display a good interface with the PVDF matrix without agglomeration. In addition, there was an improvement in the nanocomposite's stability and thermal resistance. The rGO acted as a nucleating agent, increasing the degree of crystallinity in 33% of the PVDF for all concentrations. The values of water contact angle raised from around 70° in the neat matrix to 80° in the nanocomposite. Scanning electron fractographies demonstrated the tendency of the reinforcement effect of rGO, favoring a greater ductility for cyclical loads. Finally, the results showed that incorporating rGO led to increased nanocomposite thermal performance compared to the neat polymer, revealing a promising candidate for ducts and oil pipelines.

Ultra-high molecular weight polyethylene (UHMWPE) is well known for its remarkable mechanical properties including excellent ballistic performance. These properties might be further improved by reinforcement fillers, especially nanoparticles (NPs). In the present work, UHMWPE is incorporated with 0.01, 0.05 and 0.1 wt% of boron carbide (B4C) NPs by twin-screw extrusion at 200 °C. These nanocomposites are characterized by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) and then, for the first time, ballistic tested with 0.22 caliber ammunition. HRTEM images reveal B4C NPs with sizes in the range of 10–55 nm. SEM disclosed uniform incorporation of 0.01 and 0.05 wt% B4C NPs. The nanocomposites crystallinity index, obtained by XRD, remained practically constant (44–49%) but significantly lower than the neat UHMWPE (66%). A slight decrease in the nanocomposite's thermal stability was shown by TGA, while no significant changes were found by DSC as compared to the neat UHMWPE. The DMA properties of all nanocomposites were improved. In particular, the storage modulus of the 0.05 wt% B4C nanocomposite increased by 89% compared to neat UHMWPE. The ballistic result of the 0.05 wt% B4C nanocomposite showed the lowest bullet penetration depth and confirmed its advantage for personal armor application.

Seeking to improve personal armor equipment by providing mobility and resistance to penetration, this research aimed to explore the potential of sustainable materials in order to assess their ability in ballistic applications. Titica vine fibers (TVFs) extracted from aerial roots of Heteropsis flexuosa from the Amazon region were incorporated at 10, 20, 30, and 40 vol% into an epoxy matrix for applications in ballistic multilayered armor systems (MASs) and stand-alone tests for personal protection against high-velocity 7.62 mm ammunition. The back-face signature (BFS) depth measured for composites with 20 and 40 vol% TVFs used as an intermediate layer in MASs was 25.6 and 32.5 mm, respectively, and below the maximum limit of 44 mm set by the international standard. Fracture mechanisms found by scanning electron microscopy (SEM) attested the relevance of increasing the fiber content for applications in MASs. The results of stand-alone tests showed that the control (0 vol%) and samples with 20 vol% TVFs absorbed the highest impact energy (Eabs) (212–176 J), and consequently displayed limit velocity (VL) values (213–194 m/s), when compared with 40 vol% fiber composites. However, the macroscopic evaluation found that, referring to the control samples, the plain epoxy shattered completely. In addition, for 10 and 20 vol% TVFs, the composites were fragmented or exhibited delamination fractures, which compromised their physical integrity. On the other hand, composites with 30 and 40 vol% TVFs, whose Eabs and VL varied between 166–130 J and 189–167 m/s, respectively, showed the best physical stability. The SEM images indicated that for composites with 10 and 20 vol% TVFs, the fracture mode was predominantly brittle due to the greater participation of the epoxy resin and the discrete action of the fibers, while for composites with 30 and 40 vol% TVFs, there was activation of more complex mechanisms such as pullout, shearing, and fiber rupture. These results indicate that the TVF composite has great potential for use in bulletproof vests.

Poly(vinylidene fluoride) (PVDF) with commercial rutile-TiO2, SiO2, α-Al2O3, and Fe3O4 nanoparticles were prepared via extrusion using different contents, from 0.1 to 10 wt.%. The effect of the nanoparticles in the matrix on several material characteristics, such as the thermal and mechanical properties, crystallinity degree, and permeability to CO2, were examined. X-ray diffraction and infrared analyses revealed that the successful incorporation of increasing amounts of nanoparticles in the PVDF matrix reduced the total crystallinity but increased the β-phase content in almost all nanocomposites, suggesting an improved interaction between filler and polymer.The degree of crystallinity was between 30 and 38%, and good stability to thermal degradation of the obtained.The highlight of the present work is the observation that PVDF/rutile-TiO2 and PVDF/SiO2 nanocomposites showed an increased barrier to CO2 compared with PVDF. Such a conclusion tends to demonstrate that rutile-TiO2 and SiO2 nanoparticles associated with PVDF resulted in materials applicable in the barrier layer of flexible risers.

In this paper, flower-like ZnO (FZnO) particles were synthesized through a facile method using different precursor content and reaction time. The as-prepared ZnO particles were then characterized by scanning electron microscopy (SEM), and the results showed the production of particles with varied aspect ratios (5–14). Composites of poly (vinylidene fluoride) (PVDF) with FZnO were prepared and also studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier-transform infrared (FTIR). A slight reduction of thermal properties was noticed, where the degradation temperature decreased from 439 °C for neat PVDF to around 431–438 °C for the PVDF composites with FZnO. Besides, an increase of β-crystals was observed by incorporating these particles, shifting from 31% (neat PVDF) to 37% in the composites. Furthermore, the permeability coefficient to CO2 reduced around 13%, indicated that the composites with the obtained flower-like ZnO particles might have potential applications as a barrier layer in oil ducts pipelines compared with neat PVDF.

Polycaprolactone (PCL) bionanocomposites reinforced with microfibrillated cellulose (MFC), either plain or modified with 2 wt% of zinc oxide (ZnO) nanoparticles, were first time developed for possible application as multifunctional packing. The MFC was obtained by an alkali treatment, a steam explosion process, and ZnO modification applied to parchment (PAR), a husk waste from the coffee industry. X-ray diffraction (XDR), thermogravimetric analysis (TGA/DTG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile tests, and CO2 permeability characterized the MFCs and the bionanocomposites. As for the MCFs, the crystallinity index of 50.6% measured by XRD for the plain PAR fiber increases with the combined alkaline treatment and steam explosion (CFA/EXP) to 68.2%, and further with ZnO modification (ZnO-CFA/EXP) to 80.1%. TGA/DTG displays a rising onset of thermal degradation from 214 to 306 °C, as well as maximum degradation rate from 330 to 350 °C, for PAR and ZnO-CFA/EXP, respectively. Regarding the nanocomposites, the addition of 3 wt% of alkali/steam explosion and ZnO-modified CFA/EXP contributes to enhancing thermal stability. Tensile tests disclosed improved mechanical properties of the novel nanocomposites as compared to the PCL matrix. In particular, Young's modulus rose from 88.5 to 169.5 MPa for the plain PCL and PCL reinforced with 3(ZnO-CFA/EXP), respectively. SEM images evidenced the participation of cellulose micro and nanofibrils in the PCL matrix. Approximately 20% reduction in the CO2 permeability coefficient of both PCL and its 3CFA/EXP nanocomposite compared with 3(ZnO-CFA/EXP) proved that the ZnO nanoparticles provide a gas barrier to the nanocomposite, a convenient property for food packing.

As an alternative for ordinary Portland cement, geopolymers are cost effective materials that can be prepared with relatively low energy consumption and substantial reduction of CO2 emissions. In the present study the characteristics of novel hybrid composite of geopolymer foam (GPF)/polylactic acid (PLA) and their efficiency in removing copper(II) and zinc(II) to treat high volumes of polluted water are investigated. Contrary to the conventional methods for removing heavy metals, the newly developed composites are ecological, low-cost, easily available, and economically viable alternatives providing good physical-chemical stability, ion-exchange properties, and a porous structure. Based on the sustainable advantage to produce geopolymers from recycled materials, GPFs were obtained from blast furnace slag (BFS) by reacting 20 ml of an 8 M alkaline solution of sodium metasilicate (Na2SiO3) with BFS particles and later addition of hydrogen peroxide. GPFs were produced with a stoichiometry of 1.4 and 1.6 g/L between BFS/alkali solution with a 1.6 ml solution of hydrogen peroxide 50% to develop porosity into the materials. Finally, the GPFs were coated with PLA. Specimens of GPF/PLA composites were characterized by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, thermogravimetric analysis, dynamic mechanical analysis, and field emission gun scanning electron microscopy. Adsorption analysis of Cu(II) and Zn(II), as well as ion-exchanges from aqueous solution through the composite with 1.4 and 1.6 stoichiometry, were performed using deionized water containing 0.80% Cu(II) or Zn(II). The test resulted in high performance for retaining Cu(II) and Zn(II). Under CO2 pressure at 50 bar, the gas permeation tests confirmed porous formations into the geopolymer foams coated with molten PLA.

Novel conjugated random and block terpolymers composed of two electron-donating blocks - fluorene (Flo) and carbazole (Cz) - as well as one electron-accepting unit of thiophene-benzothiadiazole-thiophene (TBT) with the same (Flo:TBT:Cz) molar ratio of 0.5:1:0.5 were synthesized. The effects of their microstructure on physico-chemical properties and the performance of photovoltaic conversion were characterized. These conjugated terpolymers displayed two absorption peaks in UV–Vis analysis around 400 and 600 nm with a similar and narrow bandgap (1.9 eV, UV–Vis film), which is suitable to be applied as p-type semiconductors in an organic solar cell (OSC). Both synthesized terpolymers presented a high average molecular weight and degradation temperature above 400 °C. OSCs were assembled for determining the power conversion efficiency (PCE). Block terpolymer with a PCE of 1.3%, higher than that of 0.9% for the random terpolymer, was used as the electron donor in a conventional cell configuration. The device's optimization improved the photovoltaic parameters, mainly the short circuit current density, which allowed a PCE of 3.2% to be achieved. These results demonstrate that the synthesis of block terpolymers is a simple and practical approach for optimizing a conjugated polymer for an efficient OSC.

An organic photovoltaic cell (OPV) is a subcategory of the third generation of photovoltaic cells. Advantages of OPV include lightness and ease of production in industrial scale. This work proposes the synthesis and characterization of two novel random and block copolymers for OPV containing fluorene (F), thiophene (T) and benzothidiazole (B) as structural units. Polymerizations were performed via the Suzuki-Miyaura mechanism. The yields obtained for both copolymers were around 65% with corresponding molar masses measured by GPC of 3394 and 4598 g/mol. From TGA, the onset degradation temperature was approximately 415 °C, while the maximum degradation temperature was around 440 °C, for both copolymers. FTIR and NMR analyses confirmed the ratio of aliphatic and aromatic carbons in the structure of both copolymers. Difference of chaining between both copolymers was verified by 13CNMR and XRD. The energy values of HOMO were -5.76 eV for random and -5.74 eV for block copolymer. Through UV-Vis spectroscopy, optical bandgaps of 2.39 and 2.34 eV were obtained for random and block polymers, respectively. Finally, LUMO energy levels of -3.37 eV (random) and -3.40 eV (block) were calculated by subtracting the optical band gap from the HOMO energy. Mobility measurements by JV method were performed in pure polymer films, rendering 1.91 × 10−6 and 1.35 × 10-8 cm2 /V.s for random and block copolymers, respectively. Copolymers were applied in conventional and inverted devices, presenting diode behavior. Energy efficiency obtained was higher for the block copolymer, which was consistent with the obtained interplanar distances estimated by XRD.

Bone remodeling for spontaneous regeneration might be achieved by a combination of collagen and hydroxyapatite (HA). The aim of the present study is to synthesize and characterize hybrid composites of HA and carbonated hydroxyapatite (CHA) with different types of collagen. For these hybrid composite synthesis, HA or CHA precursors were precipitated in solutions containing either hydrolyzed collagen (HC) or type II collagen (COL). For control, pure HA and CHA were synthesized in the absence of collagen. During the HA-based materials synthesis, in addition to HA, another calcium phosphate phase, brushite, was also produced, as confirmed by X-ray diffraction and scanning electron microscopy (SEM). In the composites, HA presented preferential crystalline growth on the (211) crystallographic plane due to the influence of both collagens. On the other hand, CHA was precipitated in its pure form, although a reduction in the crystallinity was observed with the incorporation of the carbonate groups. Calcium/phosphorous (Ca/P) mass ratios determined by energy dispersive spectroscopy (EDS) were very close to those expected for HA, 1.67, and brushite, 1.00, confirming the formation of two calcium phosphate phases. SEM/EDS results showed higher values of Ca/P for CHA than for HA, which indicates that some phosphate groups were replaced by carbonated ones.

The coffee ripe red bean is a worldwide food commodity consumed mainly as a beverage made from the roasted beans. A secondary product of the coffee industry is the oil extracted from unripe green beans. This extraction generates a solid green coffee cake (GCC) with potential to be applied as polymer composite reinforcement. For this purpose, the GCC must be treated to improve the reinforcing characteristics. The present work investigated initially the treatment of GCC by the steam explosion process and then evaluated the use of treated GCC fibers as reinforcement of composites with polypropylene (PP) matrix. The best GCC/water ratio was first determined in a steam jet reactor in association with thermogravimetric analysis. PP composites incorporated with 2 and 5 wt% by GCC fibers were fabricated by extrusion. Both plain as received and the best steam-blown GCC/PP composites were characterized by differential scanning calorimetry (DSC) and dynamical-mechanical analysis (DMA). The incorporation of treated GCC provided a higher thermostability to the composite, disclosed by DSC, as compared to the plain PP reference sample. It was also revealed that incorporation of treated GCC increased the composite degree of crystallinity. The DMA showed an improvement in the storage modulus in the range of 14–22% and decrease in the glass transition in PP/fiber composites compared to plain PP.

The global orthopedic market is forecasted to reach US$79.5 billion by the end of this decade. Factors driving the increase in this market are population aging, sports injury, road traffic accidents, and overweight, which justify a growing demand for orthopedic implants. Therefore, it is of utmost importance to develop bone implants with superior mechanical and biological properties to face the demand and improve patients’ quality of life. Today, metallic implants still hold a dominant position in the global orthopedic implant market, mainly due to their superior mechanical resistance. However, their performance might be jeopardized due to the possible release of metallic debris, leading to cytotoxic effects and inflammatory responses in the body. Poly (ether-ether-ketone) (PEEK) is a biocompatible, high-performance polymer and one of the most prominent candidates to be used in manufacturing bone implants due to its similarity to the mechanical properties of bone. Unfortunately, the bioinert nature of PEEK culminates in its diminished osseointegration. Notwithstanding, PEEK’s bioactivity can be improved through surface modification techniques and by the development of bioactive composites. This paper overviews the advantages of using PEEK for manufacturing implants and addresses the most common strategies to improve the bioactivity of PEEK in order to promote enhanced biomechanical performance.

Zinc oxide particles in needle shape were synthesized by hydrothermal route varying the reactor rotation speed (600, 1200, and 1800 rpm). The synthesized particles and commercial nanosized ZnO were characterized through X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and scanning electronic microscopy (SEM), aiming to evaluate the influence of the synthesis variable on their thermal, morphological and chemical properties. In this study, the performance of composites comprising poly(vinylidene fluoride) (PVDF) matrix and ZnO synthesized particles, and commercial nanoparticles were compared. The composites were analyzed by XRD, TGA, FTIR, SEM, dynamic-mechanical analysis (DMA), and permeability to CO2. The results revealed that the particles synthesized even in micrometric diameter reduced the permeability much more than the commercial ZnO nanoparticles, therefore being more suitable for the application as inner pressure sheath in flexible ducts. Moreover, the ZnO needle-like particles with a lower dimension induced the PVDF β-phase to over 30%.

Polymeric solar cells (PSCs) are a promising alternative for harnessing solar energy and producing clean and renewable energy. In the present work, a new photovoltaic polymer was synthesized to be applied as an electron donor in PSCs. The conjugated polymer showed high solubility. The optical and electronic properties were investigated in which it was possible to observe wide absorption band and bandgap indicating that it is a promising material for application in solar cells.

Some treatment options available to repair bone defects are the use of autogenous and allogeneic bone grafts. The drawback of the first one is the donor site’s limitation and the need for a second operation on the same patient. In the allograft method, the problems are associated with transmitted diseases and high susceptibility to rejection. As an alternative to biological grafts, polymers can be used in bone repair. Some polymers used in the orthopedic field are poly(methyl methacrylate), poly(ether-ether-ketone), and ultra-high molecular weight polyethylene (UHMWPE). UHMWPE has drawn much attention since it combines low friction coefficient and high wear and impact resistance. However, UHMWPE is a bioinert material, which means that it does not interact with the bone tissue. UHMWPE composites and nanocomposites with hydroxyapatite (HA) are widely studied in the literature to mitigate these issues. HA is the main component of the inorganic phase in the natural bone, and the addition of this bioactive filler to the polymeric matrix aims to mimic bone composition. This brief review discusses some polymers used in orthopedic applications, focusing on the UHMWPE/HA composites as a potential bone substitute.

In this study, polymeric nanocomposites based on poly(methyl methacrylate) (PMMA) and silicon carbide (SiC) nanoparticles were prepared by radical mass polymerization in the presence of filler. Nanoparticles of SiC with and without surface treatment with organosilane were obtained .The nanocomposites were characterized by X-ray fluorescence (XRF), infrared spectroscopy (FTIR), thermogravimetry (TGA) and Field Emission Gun Scanning Electron Microscopy (FEG SEM) with an energy dispersive x-ray spectroscopy (EDS) detector. The produced nanocomposites showed well-dispersed SiC incorporation in the PMMA matrix. The results pointed that the surface treatment on SiC fillers was successful on enhancing the interaction between the organic matrix and the inorganic filler.

In the present work, the synthetic route to obtain crosslinked polyethylene (PEX) was studied using vinyltrimethoxy silane (VTMS) as crosslink agent and commercial polyethylene (HDPE and LLDPE). Materials were processed with increasing amounts of VTMS (2.5, 5.0 and 7.5 wt.%). After insertion of silane onto polymer chain in solid state, samples were molded by compression. Gel content was used to measure the extension of crosslinking. Melting temperature and degree of crystallinity were evaluated using differential scanning calorimetry (DSC). The microstructure of the starting polyethylene was correlated with the effectiveness of crosslinking and the resultant thermal and mechanical properties of the PEX. Hydroxylated liquid polybutadiene (HLPB) was employed to improve crosslink efficiency, as well as mechanical properties of the material.

Nanocomposites of high-impact polypropylene resin and organosilane-functionalized nanotubes in halloysite clay were prepared with the introduction of peroxide to promote selective incorporation of the filler into the polypropylene phase of the matrix, with minor insertion into the EPR elastomeric phase, thus improving the stiffness while preserving the high toughness of the material. Silica composites were also prepared as standard filler. The effect of increasing load content on the morphological and mechanical properties of this material was evaluated by SEM and DMA. The content of the hexane-extracted fraction of these composites after processing was evaluated. Halloysite was well-dispersed in the matrix. Composites with 10% of filler and 0.5% w/w of dicumyl peroxide had increased stiffness and higher loss factor. An increase of the E’ was generated by halloysite addition, but there was a higher decrease in Tan delta. Studies using experimental planning as a tool enabled choosing appropriate amounts of DCP to obtain a high performance composite.