Breaking Elongation Research Articles

Thermo‐mechanical properties and optimization of sodium alginate as a polymer backbone substrate for biosensor application

AbstractThis study was aim to optimize the formulation of the sodium alginate biosensor substrate with incorporation of sodium alginate (1%‐6%(w/v)) as a polymer backbone and glycerol (10–50 wt%) as a plasticizer. The effect of their interaction on film's tensile strength (TS) and elongation at break (EB) were analyzed via response surface methodology‐central composite design (RSM‐CCD). The optimum parameter of the films for the maximum TS was at 1.90%(w/v) of sodium alginate and 17 wt% of glycerol and for maximum EB was at 4.89%(w/v) of sodium alginate and 49.65 wt% of glycerol. The optimum parameter of the films had revealed the better TS was at lower sodium alginate content and better EB was at higher glycerol content. In terms of thermal stability, the thermal decomposition temperature (Tonset) of sodium alginate decreased with the incorporation of glycerol.

Physico-Chemical Characteristics of pH-Driven Active Film Loading with Curcumin Based on the Egg White Protein and Sodium Alginate Matrices

The low solubility and stability of fat-soluble curcumin in water limit its application in active packaging. This study explored the use of a pH-driven method to investigate the preparation and enhancement of the performance of films loaded with curcumin in a matrix of sodium alginate (Alg) and egg white protein (EWP). In this study, the EWP, Alg, and curcumin primarily bind through hydrogen bonding, electrostatic interactions, and hydrophobic interactions. Compared to EWP films, the films loaded with curcumin through the pH-driven method exhibited enhanced extensibility and water resistance, with an elongation at break (EB) of 103.56 ± 3.13% and a water vapor permeability (WVP) of 1.67 ± 0.03 × 10−10 g·m/m2·Pa·s. The addition of Alg improved the encapsulation efficiency and thermal stability of curcumin, thereby enhancing the antioxidant activity of the film through the addition of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, which resulted in 106.95 ± 2.61 μg TE/g and 144.44 ± 8.89 μg TE/g, respectively. It is noteworthy that the detrimental effect of Alg on the color responsiveness of films containing curcumin has also been observed. This study provides a potential strategy and consideration for the loading of low water-soluble active substances and the preparation of active packaging.

Gelatin/agar pH-indicator film based on cranberry extract loaded with linalool nanoparticle: Survey on physical, antimicrobial, and antioxidant properties

In this study, linalool-nanoparticles (L-NPs) were prepared (encapsulation efficiency was 68.54 %) and introduced pH-indicator film based on cranberry-extract (CEF) to develop multifunctional smart films. XRD analysis and FTIR spectroscopy indicated that cranberry-extract (CE) and L-NPs were uniformly distributed in the gelatin/agar matrix and could change the intermolecular structure of the film. Color change of smart films showed that CE endowed the film with pH-sensitive property. As CE and L-NPs were added to the film, the water contact angle (WCA) was increased from 57.03° to 117.73°, the elongation at break (EAB) was increased from 12.30 % to 34.60 %. Additionally, the introduction of L-NPs enhanced the antioxidant activity (DPPH free radical scavenging rate increased from 26.80 % to 36.35 %) and antibacterial activity (against S. aureus and E. coli) of the smart film, which were verified by its retarding effect on pork spoilage.

Trisodium phosphate-loaded magnesium‑aluminum layered double hydroxides/oxidized-multiwalled carbon nanotubes self-assembled 2D-nanohybrid for designing a multifunctional smart epoxy nanocomposite

In this study, a hybrid nanomaterial based on layered double hydroxides (LDH) and multi-walled carbon nanotubes (MWCN) was fabricated using a co-precipitation method. Trisodium phosphate (TP) was loaded into the designed nanocarrier to enhance the corrosion resistance of mild steel in 3.5 wt% NaCl media. Fourier transform infrared (FT-IR) spectroscopy, Raman, and X-ray diffraction (XRD) analyses were carried out to investigate the magnesium‑aluminum layered double hydroxides/oxidized-multiwalled carbon nanotubes (Mg-AL-LDH/O-MWCN) structure and morphology before and after loading of trisodium phosphate. Furthermore, the nanocarrier inhibition capability was evaluated through electrochemical impedance spectroscopy (EIS), polarization, and field emission-scanning electron microscopy (FE-SEM) techniques. Electrochemical impedance spectroscopy (EIS) was also employed to estimate the anticorrosion properties of the epoxy coating loaded with TP-LDH/O-MWCN. The EIS evaluation of the intact coating revealed the impedance at the lowest frequency (|Z|0.01 Hz) of about 109 Ω.cm2 after 42 days of immersion for the trisodium phosphate-layered double hydroxides/oxidized-multi-walled carbon nanotubes@epoxy (TP-LDH/O-MWCN@EP) sample and the lowest value of breakpoint frequency was obtained for this sample (fb = 0.063 Hz). These findings prove the trisodium phosphate-layered double hydroxides/oxidized-multi-walled carbon nanotubes (TP-LDH/O-MWCN) particles' effectiveness in the epoxy coating water/ion barrier function enhancement. EIS results indicated the enhancement of the charge transfer resistance (Rct) of the scratched coatings, from 65.97 kΩ.cm2 for the pure epoxy (EP) sample to 94.87 kΩ.cm2 for the trisodium phosphate-layered double hydroxides/oxidized-multi-walled carbon nanotubes@epoxy (TP-LDH/O-MWCN@EP) sample, revealing the self-repairing behavior of the designed coating. In addition, the adhesion properties of the samples coated with LDH/O-MWCN@EP and TP-LDH/O-MWCN@EP were studied by pull-off and cathodic disbonding tests, leading to a 33% reduction in adhesion loss and a 52.23% reduction in the diameter of cathodic delamination. The tensile test conducted on the samples indicated an increase in the ultimate tensile strength (σUTS), elongation break (Ɛb), and toughness values by 188%, 223%, and 800%, respectively, in comparison with the pure epoxy (EP) sample.

Fabrication and characterization of pullulan/tapioca starch-based antibacterial films incorporated with Litsea cubeba essential oil for meat preservation

Active packaging is a novel technology that utilizes active materials to interact with products and the environment, improving food shelf life. The purpose of this work was to fabricate a multifunctional film using Litsea cubeba essential oil (LC-EO) (1 %, 3 %, 5 %, and 7 %) as the active ingredient and pullulan(P)/tapioca starch (TS) as the carrier material. Adding essential oil improves the films properties, such as barrier ability, anti-oxidant, and antibacterial activity. However, tensile strength (TS) and elongation at break (EAB) were slightly reduced from 28.94 MPa to 11.29 MPa and 15.36 % to 12.19 %. The developed PTS3% films showed the best performance in mechanical properties, especially EAB (14.26 %), WVP (3.26 %) and OP (3.13 %), respectively. The inhibitory zone diameters in the agar-well diffusion test were 18.59 mm for Staphylococcus aureus and 17.32 mm for Escherichia coli. Further study was conducted to compare the preservation effects of film with low-density polyethylene bag (LDPE) on chilled beef. Remarkably, PTS3% film decreased the bacterial population in beef meat while maintaining the pH, color, texture, and TBARS levels within an acceptable range for ten days of storage at 4 °C rather than in a low-density polyethylene bag. The outcomes indicated the potential of PTS3% films in food packaging applications.

Investigation on the Duration of Action of Mg3N2 as a Grain Refiner for AZ80 Alloy

In magnesium alloys with aluminum as an alloying component, zirconium loses its grain refinement effect as a grain refiner. Instead of zirconium, Mg3N2 can be used, and promising results have already been obtained. However, the duration of action of Mg3N2 has not been elucidated yet. The aim of this work is therefore to determine the grain size of the AZ80 alloy as a function of the duration of action of Mg3N2 and thus the economically reasonable duration of use. It was found that the Mg3N2 reaches its full effect from 30 min after a complete remelting and does not lose this grain refinement effect even after 90 min. It thus proves to be a stable and reliable grain refiner. A grain size of 146.3 ± 10.3 µm was achieved. Furthermore, a minimum tensile strength of 205 MPa with a break elongation of 5.99% was achieved.

Fabrication of smart film based on fish gelatin incorporating phycoerythrin and cellulose nanofibrils to monitor fish freshness

Phycoerythrin (PE) extract from red algae Laver (Pyropia dentata) was used in the fabrication of a smart packaging film. The PE showed pH sensitivity, implying unique color shifts at different pH. The film colors altered from red through purple-brown to colorless with increasing pH. The smart packaging films were prepared by casting method composed of gelatin (GE), sodium alginate (SA), and cellulose nanofibrils (CNF). The films were coded as GE/SA (control), GE/SA/PE, and GE/SA/CNF/PE. The thickness of the films ranged from 0.24 ± 0.02 mm to 0.33 ± 0.01 mm. The mechanical properties tensile strength (TS) (12.24 ± 0.30 MPa to 17.65 ± 0.33 MPa) and elongation at break (EAB) (79.34% ± 1.02%–93.36% ± 0.69%) significantly increased after addition of CNF. The synthesized films showed water contact angle ranged from 84.55 ± 2.12 to 69.41 ± 1.21, suggesting that films were hydrophobic. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis demonstrated strong interaction among PE, CNF, and biopolymers. The film with GE/SA/CNF/PE exhibited higher thermal stability compared with control film. Then, the films were applied for checking real time application for the freshness of salmon fish. The significant color change of the film occurred and the number of bacterial colony and TVB-N were increased from 3.81 Log CFU/g to 6.94 Log CFU/g and from 4.78 mg/100 g to 32.27 mg/100 g after incubation for 48 h. Therefore, the film with PE and CNF was intended as an excellent candidate for smart packaging film.

Synthesis of grafted bromoisobutyryl esterified starch using electron transfer atom transfer radical polymerization method with high-performance adhesion and film properties

Nowadays, few investigations on the process parameters of grafted starch synthesized using electron transfer atom transfer radical polymerization (ARGET ATRP) and its applications in warp sizing and paper-making are presented. Therefore, this study aimed to survey the appropriate process parameters of bromoisobutyryl esterified starch-g-poly(acrylic acid) (BBES-g-PAA) synthesized by the ARGET ATRP, and also aimed to provide a new biobased BBES-g-PAA adhesive. The appropriate synthesis process parameters were 1.2, 0.32, and 0.6 in the molar ratios of vitamin C, CuBr2, and pentamethyldivinyltriamine to BBES, respectively, at 40 °C for 5 h. The BBES-g-PAA samples with a grafting ratio range of 4.63–14.14 % exhibited bonding forces of 57.8–64.6 N to wool fibers [55.5 N (BBES) and 53.8 N (ATS)], and their films showed breaking elongations of 3.29–3.80 % [2.74 % (BBES) and 2.49 % (ATS)] and tensile strengths of 29.1–25.4 MPa [30.4 MPa (BBES) and 34.7 MPa (ATS)]. Compared with BBES, significantly increased bonding forces and film elongations, and decreased film strengths for the BBES-g-PAA samples with grafting ratios ≥10.54 % were displayed (p < 0.05). The time (100–42 s) taken for the BBES-g-PAA films was significantly shorter than that of ATS (246 s) and BBES (196 s) films (p < 0.05), corresponding to better desizability.

A rare‐earth‐based nano‐flame retardant with 2D MXene for improving fire safety and mechanical property of thermoplastic polyurethane composites

AbstractA kind of rare earth flame retardant, two‐dimensional lamellar compounds (MXene) loading with cerium phosphate nanorod, MXene@CePO4 (CMX) was prepared by hydrothermal and electrostatic adsorption methods. It was then applied in thermoplastic polyurethane (TPU). With the 3 wt% addition of CMX improving the mass rate of residual char from 4.42 wt% to 11.33 wt% compared to pristine TPU, there were reductions of 53.8%, 12.3%, and 24.7% in peak heat release rate (pHRR), total heat release (THR), and smoke density maximum (Ds max), respectively. Moreover, the TPU/CMX composites were shown to have superior mechanical properties compared with pristine TPU. For TPU/CMX‐3.0, there was a visible improvement in tensile strength (TS) and elongation at break (EB) of 12.5% and 54.1% respectively, compared to pure TPU. The analysis of the flame retardancy mechanism of TPU/CMX shows that CMX plays an effective role in quenching free radicals in the gas phase and promotes char formation of TPU in the condense phase. Therefore, this paper offers a new solution for designing multifunctional rare earth flame retardants that are applied in TPU, thereby extending its application in industries and daily life.

Development of soy protein isolate-based orally disintegrating film: Improvement of disintegration speed, mechanical properties, and thermal stability by β-Cyclodextrin

The effect of β-Cyclodextrin (β-CD) at different concentrations (0–20% w/w) on the function and properties of soy protein isolate (SPI)-based orally disintegrating films (ODF) was studied. The results of moisture content and contact angle indicate that the inclusion of β-CD enhances the moisture content and surface hydrophilicity of ODF. The thickness ODF samples is between 0.031 and 0.041 mm. Due to the addition of β-CD, ODF disintegration rates increased by 47.86%–64.62%. Scanning electron microscope, and mechanical analysis show that ODF with a β-CD concentration of 10% w/w has the best performance, presenting the smoothest surface, maximum tensile strength (TS) and elongation at break (EB). FTIR spectrum results show that there are physical entanglements and hydrogen bonding interactions between SPI and β-CD, and appropriate concentrations of β-CD (5% w/w and 10% w/w) can transform random coils into β-sheets. Once the concentration exceeding 10% w/w, β-CD will crystallize and precipitate on the ODF surface, which weakens the mechanical properties of the ODF and the strength of the SPI network structure. Thermogravimetric test results show that β-CD improves ODF thermal stability. This research offers a significant theoretical foundation for the advancement of ODF that are protein-based and not hydrolyzed.

Alloying synergistic flame retardant effect on PA6 by polyimide containing alkyl hypophosphate structure

A novel flame retardant − bismaleimide polyalkyl phosphinate aluminium (BPPA), containing both imide and phosphinate structures, was designed and synthesized to investigate the intramolecular synergistic flame retardant effect between imide and phosphinate structures and alloying effect of the imide structure with PA6. Based on the flame retardant and mechanical properties of BPPA/PA6 composites, the alloying flame retardant effect of BPPA on PA6 was systematically investigated. The PA6 material had almost no char after burning; however, BPPA can produce a large amount of residue and form a dense char layer during combustion of PA6 matrix, effectively reducing the heat release, while BPPA also improved the mechanical properties of PA6 composites through the alloying effect. The peak heat release rate (pk-HRR) decreased by 55.8 %, and the residue yield increased by 9.2 wt% for 20BPPA/PA6, compared with the PA6. After compounding aluminum diethylphosphinate (ADP) and BPPA, the flame retardancy of the composites can be further improved. The LOI value of the 8ADP/6BPPA/PA6 was increased to 29.8 % and passed the test of UL94 V-0 level. Its pk-HRR and residue yield were similar to that of the 14BPPA/PA6, which indicated that the compounding system of ADP and BPPA can provide excellent charring properties and gas-phase flame retardancy of PA6. Meanwhile, the alloying BPPA with PA6 not only reduced the effect on the tensile strength of ADP on PA6, but also improved the breaking elongation of the composite. In conclusion, it provides a new direction for developing high-performance halogen-free flame retardant polyamides.

Recycled rubber wastes-based polymer composites with flame retardancy and electrical conductivity: Rational design, modeling and optimization

Polymer recycling techniques experience a maturity period of design and application. Rubbers comprise a high proportion of polymer wastes, highly flammable and impossible to re-melt. Polymer composites based on ground tire rubber (GTR) and ethylene-vinyl acetate copolymer (EVA) containing carbon black (CB) (1–50 phr), with variable EVA/GTR weight composition (10/90, 25/75, 50/50, 75/25 and 90/10), and processing temperature (Low: 100 °C and High: 200 °C) were designed applying Design of Experiments (DOE) approach of Optimal Design. The properties and performance features were experimentally evaluated. The tensile strength (TS) and elongation at break (EB) were optimized using Desirability Function (DF) approach. A wide fluidity window (Labeled POOR, GOOD, and EXCELLENT) and mechanical properties were observed. Overall, higher values of EB were assigned to samples processed at 200 °C. Cubic regression modeling and DF optimization of TS and EB indicated unlikely that one expect a TS ≥ 3 MPa, while EB values more than 500% were likely regardless of CB content for EVA-rich composites. The electrical properties of CB/EVA/GTR samples were examined by impedance spectroscopy technique. An interesting relationship was observed between the DC conductivity and the EVA/GTR ratio and processing temperature. GTR-rich samples showed much higher conductivity than EVA-dominated samples, attributed to the presence of CB in the rubber waste, which, together with the added CB, was able to create conduction paths for the transported electrons. Higher processing temperature of 200 °C improved dispersion of the added CB, i.e. a more even distribution of the conductive phase in the matrix. The uniform and evenly dispersed domains of particles were detected by SEM images for highly CB loaded composites. Surprisingly, 50/50 EVA/GTR composites were resilient against flame, while thermally stable ones in TGA measurements were highly CB loaded ones.

Sweet cherry tree (Prunus avium) exudate gum-based film modification in a photoreactor: Effects of hydrogen peroxide oxidation, UV irradiation, and TiO2 nanoparticles

The fabrication possibility of nanocomposite film from sweet cherry tree exudate gum (SCG) was studied. To improve SCG film properties, oxidation with hydrogen peroxide, ultraviolet irradiation (UV-A and UV-C), and TiO2 nanoparticles (T-NPs) were used. Hydrogen peroxide oxidation at higher amounts decreased the water vapor permeability (WVP) and thickness and increased the mechanical properties and transparency. In comparison with the UV-A, UV irradiation of the C-type increased permeability, and elongation at break (EAB) and thickness, but reduced the tensile strength (TS), solubility, and transparency. The permeability and tensile strength were increased and elongation at break was decreased at a longer time of irradiation. The transparency values of fabricated films ranged from 65.3 to 79.5 % and WVP were in the range of 2.32–4.72 (×10−10 g/m.s.Pa). The measured TS of the SCG films were between 2.2 and 5 MPa and the EAB of the SCG films was between 35 and 68.7 %. The FTIR spectrum and SEM images revealed that the treatments could affect the bonds and the smoothness of the film surface, respectively. Images provided by AFM showed that the roughness of the films was increased by the addition of T-NPs. The incorporation of T-NPs increased the TS and decreased EAB and WVP. These results indicated that oxidation, UV irradiation and nanomaterials incorporation could be used to improve SCG film properties that are related to food packaging material.

A self-healing and recyclable polyurethane composite film for durable pH responsive coating

Wearable pH sensors can offer a visual warning signal of pH changes, making them particularly attractive in health monitoring and environmental detection. However, the fabrication of durable wearable pH sensors remains challenging due to the inevitable damage that sensors suffer in practical applications. Here, a durable pH responsive coating fabric with outstanding self-healing and recyclable capabilities is prepared with a composite film composed of a dynamic boroxine-polyurethane (BPU) and a pH responsive Congo red-based polymeric dye (CRPD). The BPU/CRPD composite film exhibits a high tensile strength of 17.46 MPa, breaking elongation of 407 %, toughness of 31.61 MJ/m3, Young’s modulus of 11.78 MPa, and outstanding elastic restorability. The high reversibility of boroxines and hydrogen bonds enable the composite film with healing efficiency of 87 % at 70 °C for 2 h and recycling efficiency of 97 % under 3 MPa at 80 °C for 5 min. In addition, the BPU/CRPD coated fabric presents outstanding pH responsive property and color fastness. Importantly, the scratched coating fabric can be easily healed at 70 °C, 5 MPa for 5 min or using an electric iron. Furthermore, the BPU/CRPD coatings on the discarded fabric can be recycled and reused many times with similar pH responsive behavior. The outstanding fastness, self-healing and recycling properties promote the durability of the pH responsive coating. This work provides a meaningful strategy for developing durable pH responsive coating fabrics with self-healing and recycling capabilities that will be promising for wearable pH sensors.

Incorporating Nigella sativa nanoemulsion into gelatin-guar gum films for enhanced healing of wound infections

Aim: This study aims to investigate the impact of incorporating Nigella sativa essential oil nanoemulsion (NSNE) into gelatin (Ge) and guar gum (GG)-based films at various concentrations (0%, 2%, 4%, and 6%) and to evaluate the antimicrobial properties of the resulting films against common bacterial strains associated with wound infections.&#x0D; Methods: The nanoemulsion (NE) was obtained through ultrasonic irradiation. Polydispersity index, zeta potential, and particle size of NE were measured. For film preparation, gelatin (Ge) and guar gum (GG) were used, incorporating NSNE at concentrations of 0%, 2%, 4%, and 6%. Mechanical properties were evaluated using an universal testing machine, film thickness with a micrometer, and crystalline structure through XRD analysis. SEM was utilized for microstructure examination, and hydrophobicity was assessed by contact angle measurements. Antimicrobial activity was determined via the disk diffusion method against bacteria relevant to wound infections. Statistical analysis employed one-way ANOVA and Tukey post hoc tests with a significance level set at 5%.&#x0D; Results: The particle size, polydispersity index (PDI), and zeta potential of the nanoemulsion were measured as 296±4.85 nm, 0.569±0.2, and -35.2±07 mV, respectively. The incorporation of NSNE into GE-GG-based films demonstrated promising antimicrobial efficacy against common wound infection bacteria, including Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, and Klebsiella pneumoniae. The films maintained mechanical integrity, with no significant alterations in tensile strength (TS) and elongation at break (EAB) (p  0.05). However, higher NSNE concentrations led to decreased hydrophobicity (p &lt; 0.05) and structural changes, as evidenced by increased pores and cracks observed in SEM images. &#x0D; Conclusion: This study highlight the potential of NSNE-containing films for wound healing applications, combining antimicrobial properties with a biocompatible film matrix.

Construction of self-healing multifunctional hyper-crosslinked hyperbranched polymer @ metal–organic polyhedra (HHMOP) membranes

The preparation of hybrid membranes composed of polymer matrix and porous materials is a hot topic. Herein, a highly reversible hyper-crosslinked hyperbranched polymer @ metal–organic polyhedra (HHMOP) membrane was designed and synthesized using hyperbranched polyamide amine (HPMA), UiO-66-NH2, diethylenetriamine, and terephthalaldehyde through a multi-component Schiff-base condensation reaction of aldehyde and amine groups. The structures of HHMOP membranes were characterized by FTIR, XRD, and SEM. The mechanical properties, thermal properties, reversible self-healing properties, and biological activity of the membranes were studied. Introducing HPMA as hyper-crosslinking monomer and UiO-66-NH2 as porous comonomers into the network resulted in HHMOPs membranes with multiple functionalities: flexibility, humidity sensitivity, self-healing capacity, antibacterial capacity and better mechanical properties than the original polyimine films. The tensional intensity and breaking elongation of HHMOP membrane has been remarkably ameliorated, with the maximum tensile strength reached 54.64 MPa. The membranes showed humidity-sensitive mechanical properties and excellent self-healing performance, with 91.35 % strength revovered after 24-hours at room temperature and a relative humidity of 60 %, indicating that HPMA has a significant impact on the humidity responsiveness and self-healing performance of HHMOP membranes. The HHMOP membrane also demonstrated good antibacterial activity against common food lethal bacteria like the gram-positive Staphylococcus aureus and gram-negative Escherichia coli. This work will greatly enrich the devise and preparation of versatile membranes and broaden the use of MOFs.

СВЧ ЭЛЕКТРОТЕХНОЛОГИЧЕСКАЯ УСТАНОВКА ДЛЯ МИКРОВОЛНОВОЙ ОБРАБОТКИ ПИЛОМАТЕРИАЛОВ И ПОЛИКАПРОАМИДНЫХ НИТЕЙ

Research was carried out to determine the optimal modes for the simultaneous processing of lumber and polycaproamide threads in a hybrid microwave electrotechnological installation. The work was carried out on an installation with a hybrid-type chamber with adjustment of the microwave power level of the magnetrons and the duration of exposure. Two possible designs of a hybrid installation for processing lumber and polycaproamide threads are presented, differing in that in one the lumber was processed inside the chamber, and the polycaproamide threads were pulled through waveguides using bobbins and an electric motor installed outside the chamber, and in the second, both materials were processed inside the installation chamber. The object of research is lumber and polycaproamide threads. Lumber was loaded into the working chamber in the form of a stack, which rotated along its axis, and a structure was examined in which polycaproamide threads were pulled through a waveguide extending from a source of microwave energy outside the chamber. The time of exposure to microwave radiation on lumber and half-caproamide threads was measured using electronic stopwatches; temperature and humidity were measured using a Testo 905T2 thermometer, a Testo 830T1 pyrometer, and a Testo 606-1 digital hygrometer. The use of a hybrid microwave electrotechnological installation reduced the processing time of lumber due to rotation in the microwave field to 15 hours, while ensuring the required quality of the dried material (final moisture content - 7.1%, reduction in chipping and impact bending strength within 5%). The relative breaking elongation of polycaproamide threads increased by 48.2%, and the breaking load – by 27.6%. Thanks to the simultaneous processing of lumber and polycaproamide threads, it is possible to reduce metal consumption and increase the energy efficiency of the installation.

Fabrication and Characterization of a Bioscaffold Using Hydroxyapatite and Unsaturated Polyester Resin.

Outstanding biodegradability and biocompatibility are attributes associated with particular polyester substances that make this group useful in specific biomedical fields. To assess the potential as a biomaterial, a novel composite consisting of hydroxyapatite (HAp) and unsaturated polyester resin (UPR) was developed in this work. Using a hand-lay-up technique, various percentages (50, 40, 30, 20, and 10%) of HAp were reinforced into the UPR matrix to fabricate composite materials out of glass sheets. Prior to processing of the composite samples, hydroxyapatite was chemically synthesized in a wet chemical manner. Using a universal testing machine (UTM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermo-gravimetric analysis (TGA), the fabricated samples were characterized. The crystallographic parameters of synthesized hydroxyapatite (HAp) were also estimated through a range of formulas. The optimal amount for hydroxyapatite was 40% according to the findings of the tensile strength (TS), tensile modulus (TM), percentage of elongation at break (EB), bending strength (BS), and bending modulus (BM). Improvements in TS, TM, BS, and BM for the ideal combination were 39.39, 9.21, 912.05, and 259.96%, in each case, over the controlled one. Thermogravimetric analysis (TGA) has been implemented to determine the degradation temperature of the fabricated composites up to 600 °C.

Terminal modified polyesters with improved tensile properties based on plasticization and π-π stacking effects

Mechanical properties are essential for polyester materials due to their widespread applications as fibers, films, and engineering accessories. The copolymerization strategy has been developed to enhance polyester properties, but facile-synthesized new materials are still under discovery. In this work, we designed a series of terminal functioned polyesters, for introducing plasticization effects and π-π stacking interactions. The fabrication process can be one-pot achieved via melting polycondensation method. The prepared modified polyesters exhibit significantly improved elongation of break (560%), which is 104% improved compared with pristine poly(ethylene terephthalate). Meanwhile, the maximum toughness reaches 206.1 MJ/m3. The thermal properties, viscoelastic properties, crystallinity properties, and fracture morphologies of the as-prepared polyesters are investigated as well. Results show that great elongation of break, higher crystallinity, and good processability are achieved simultaneously. This work provides a one-pot fabricated terminal functioned polyester with advanced tensile properties, expanding its potential application as engineering materials.

Surface modification of Luffa and Maize fibers by using alkali medium

Agricultural biomass is a well-known renewable resource that has a high rate of recycling. Two of them are luffa sponge and corn husk/maize fibers. Luffa sponge may be effectively used to reinforce lightweight composite constructions because of its polypore structure. For this race, maize fiber is also appropriate. Surface modifications for both of the fibers are needed for increasing mechanical strength with higher interfacial bonding with the matrix materials of composite manufacturing. This investigation involved treating both materials with 5 g/L, 10 g/L, and 15 g/L of NaOH in order to describe the alterations occurring on their physio-chemical characteristics. The therapy lasted 60 min and was administered at 90 °C. Following that, acetic acid was used to neutralize the samples. The ASTM D1445 technique was used to measure the bundle fibers' breaking force and elongation, and the ASTM D570 procedures were used in order to determine the water absorption variation % in the treated samples. The FTIR test and SEM examination revealed the contaminants that were eliminated from the surface of Luffa and Maize fibers. The test findings demonstrated improved modification behaviors for the 15 g m/L treated fibers, which had an elongation percentage of 3.02% and an equivalent breaking force of 5.12 kg for the Luffa fiber and 5.72 kg for the maize fiber. Natural contaminants were eliminated as a result of variations in functional group intensity shown in the FTIR pictures. However, SEM pictures showed that the surface smoothed out for samples treated with 15 g per liter of NaOH, which may be the cause of the fiber's brittle interlocking with the matrix components. Moreover, water absorbency rose by over 300% compared to the untreated fibers. In summary, samples treated with 10 g/L NaOH might serve as superior reinforced materials of composite for both types of fibers.