Synthesis and physicochemical study of bisphenol‐C‐formaldehyde‐toluene diisocyanate polyurethane–jute and jute–rice husk/wheat husk composites

Bisphenol‐C‐formaldehyde‐toluene‐2,4‐di isocyanate polyurethane (PU) has been synthesized at room temperature and used for the fabrication of jute and jute–rice husk/wheat husk hybrid composites. PU–jute and PU–jute–RH/WH composites were prepared under pressure of 30.4 MPa at room temperature for 8 h, while PU–jute–RH/WH composites were prepared under same pressure at 110°C for 5 h. PU–jute composite has good tensile strength and flexural strength (50–53 MPa), while PU–jute–RH/WH hybrid composites have moderate tensile strength (9–11 MPa) and a fairly good flexural strength (15–31 MPa). Composites possess 1.1–2.2 kV electric strength and 0.94–1.26 × 10¹² ohm cm volume resistivity. Water absorption in PU–jute composite is different in water (9.75%), 10% HCl (12.14%), and 10% NaCl (6.05%). Equilibrium water uptake time in salt environment is observed 96 h, while in pure water and acidic environments it is 192 h. In boiling water equilibrium water content and equilibrium time are found to be 21.7% and 3 h, respectively. Water absorption increased 2.2 times in boiling water, whereas equilibrium time reduced 64 times. Thus, PU–jute composite has excellent hydrolytic stability against boiling water, 10% HCl, and 10% NaCl solutions. Fairly good mechanical and electrical properties and excellent hydrolytic stability of composites signify their usefulness for low cost housing units and in electrical and marine industries. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2363–2370, 2006     

Preparation and Physicochemical Study of Hybrid Glass-Jute (Treated and Untreated) Bisphenol-C-Based Mixed Epoxy Phenolic Resin Composites

Glass-jute (treated and untreated) composites of mixed matrix materials [epoxy resin of bisphenol-C (EBC) and bisphenol-C-formaldehyde (BCF) of 50 wt.% of glass-jute fibers] have been prepared by hand layup technique at 150°C under 7.6 MPa pressure for 2 h. The hydrophilic character of the jute fibers has been reduced by acrylation of alkali-treated fibers with acrylic acid. Tensile strength increased from 87 MPa to 112 MPa (28.73%) and flexural strength increased from 66 MPa to 89 MPa (34.84%) on alkali treatment and acrylation. Similarly, electric strength increased from 2.71 to 3.89 kV/mm (43.54%) and volume resistivity increased from 1.23 × 10¹² to 1.77 × 10¹² Ω cm (143.90%). The edges of the 5 cm × 5 cm specimens were sealed with matrix material and subjected to distilled water and 10% each of aq. HCl and aq. NaCl solutions at room temperature for a water uptake study. The equilibrium water uptake was reduced drastically from 12.07–7.69% to 6.17–3.39% on acrylation. Similarly, diffusivity was also found to be reduced from 1.99–0.99% to 0.96–0.45%. Drastic reductions in water uptake and diffusivity are due to the replacement of hydrophobic ester groups. The reduction of water uptake is probably due to weak H-bond formation with ester and CH=CH groups, and π-electrons of benzene rings. No effect of boiling water is observed on the stability of the composite. Saturation time in boiling water was reduced twenty-eight/twenty-one times without any damage to the untreated/treated jute-glass composites, respectively.     

Fabrication and comparative mechanical,electrical and water absorption characteristic properties of multifunctional epoxy resin of bisphenol-C and commercial epoxy-treated and -untreated jute fiber-reinforced composites

Epoxy resin of bisphenol-C-formaldehyde (EBCF) was synthesized and its structure was confirmed by FTIR and ¹HNMR techniques. Untreated jute and a 4 % sodium hydroxide-treated jute composites of EBCF, araldites (GY508 and GY6010) and their hybrid composites were fabricated by hand layup technique followed by compression-molding technique. Mechanical, electrical and water absorption behavior of the composites was studied by standard test methods. The composites showed good mechanical and electrical properties, excellent hydrolytic stability and almost identical water absorption tendency. To some extent, alkali-treated jute composites displayed improved mechanical properties and water absorption tendency. EBCF-based jute and hybrid composites showed comparable mechanical and electrical properties and water absorption behavior with araldite-based composites. Among jute–EBCF, jute–araldite and their hybrid composites, J–EBCF showed the highest impact strength (26 kg m^?2), Barcol hardness (34), volume resistivity (2.7 × 10^?11 Ω cm) and diffusivity (7.19 × 10^?13 m² s^?2). J–GY-1 showed the highest tensile strength (43.7 MPa), flexural modulus (4.26 GPa), % equilibrium water absorption (19.36 %) and equilibrium water absorption time (480 h). Good mechanical and electrical properties and excellent hydrolytic stability of both types of the composites suggested their usefulness for low load-bearing housing, and electrical and marine applications. Thus, EBCF has found its commercial importance as that of the commercial araldite resins.     

Synthesis,fabrication, mechanical,electrical, and moisture absorption study of epoxy polyurethane–jute and epoxy polyurethane–jute–rice/wheat husk composites

Bisphenol‐C‐epoxy‐toluene diisocyanate polyurethane (PEBCT) has been synthesized and used for the fabrication of jute, jute–rice husk (JRH), and jute–wheat husk (JWH) composites. The composites have been fabricated by hand lay‐up technique under a hydraulic pressure of 30.4 MPa at 135°C for 2.5 h. PEBCT‐J, PEBCT‐JRH, and PEBCT‐JWH possess respectively, tensile strength of 37.4, 9.5, and 14.7 MPa, and flexural strength of 39.6, 12.9, and 21.3 MPa, electric strength of 1.3, 1.8, and 1.9 kV/mm and volume resistivity of 1.40 × 10¹³, 1.84 × 10¹³, and 1.91 × 10¹³ ohm cm. Tensile strength and flexural strength have decreased, while electric strength and volume resistivity are improved upon hybridization. PEBCT‐JWH has better interfacial bond strength and stiffness as compared to PEBCT‐JRH. Moisture uptake behavior of PEBCT‐J in water, 10% HCl and 10% NaCl at room temperature is quite different. Equilibrium moisture content of PEBCT‐J in 10% NaCl (5.5%) is almost half of those in water (11.3%) and 10% HCl (13.6%) environments. Equilibrium time for saline environment is also comparatively low. Equilibrium moisture uptake in boiling water has increased 1.84 times, while equilibrium time has decreased 15.3 times. The composites may be useful for low load bearing in construction industries and for marine applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Mechanical,Electrical and Water Absorption Study of Jute/Glass/Jute-bamboo/Glass-bamboo-bisphenol-C-formaldehyde-acrylate a Value Added Composites

Bisphenol-C-formaldehyde-acrylate (BCFA) resin was synthesized by reacting 0.1 mol bisphenol-C-formaldehyde resin, 0.4 mol acrylic acid in 25 ml 1,4-dioxane and 1.5 g phenothiazine catalyst at 80°C for 6 h. Jute, glass, jute-bamboo, and glass-bamboo composites were prepared by compression molding technique at 150°C for 2 h under 30.4 MPa pressure. Jute-BCFA, Glass-BCFA, Jute-bamboo-BCFA, Glass-Bamboo-BCFA possess 50, 114, 49, and 65 MPa tensile strength; 58, 185, 69, and 70 MPa flexural strength; 1.2, 3.3, 1.3, and 1.9 kV/mm electric strength and 6.2 × 10¹², 2.5 × 10¹³, 6.6 × 10¹², and 1.5 × 10¹³ ohm cm volume resistivity. The data are interpreted in terms of nature of fibers and resin and fiber loading and orientation. Water absorption behavior of composites is tested in pure water, 10% NaCl and 10% Hcl solutions at room temperature as well as in boiling water. Observed diffusivity order for each of composite is H₂O < NaCl < HCl. Sandwich composites shown high water absorption in all media due to high bamboo fiber loading and fiber agglomeration. The presence of HCl and NaCl affected the water structure and hence diffusivity. Jute-bamboo-BCFA and Glass-Bamboo-BCFA delaminated in boiling water within half an hour. Mechanical and electrical properties and water absorption behavior are affected by the nature of fibers and matrix, fiber loading and fiber arrangement. Fairly good mechanical and electrical properties of Jute-BCFA and Glass-BCFA and their low water absorption behavior signify their usefulness as low load bearing applications. Composites signify their use for low load bearing applications in construction, electrical and marine industries.     

The Preparation and PhysicoChemical Study of Glass,Jute and Hybrid Glass-Jute Bisphenol-C-Based Epoxy Resin Composites

Glass-PA (EC-G-PA), Jute-PA (EC-J-PA), Glass-Jute-Glass (EC-GJG-PA), Jute-Glass-Jute (EC-JGJ-PA) composites of epoxy resin of bisphenol-C (EBC) have been prepared using a hand lay-up technique at 150°C under 27.58 MPa pressure for 6 h by using phthalic anhydride as a curing agent. EC-G-PA, EC-J-PA EC-GJG-PA and EC-JGJ-PA Possess 34, 41, 27 and 21 MPa tensile strength; 34, 27, 19 and 22 MPa flexural strength; 1.9, 1.0, 1.6 and 1.3 kV/mm electric strength and 4.2 × 10¹³, 1.2 × 10⁹, 8.7 × 10¹¹ and 4.0 × 10¹¹ ohm.cm volume resistivity. Hydrolytic stability of the composites was tested against water, 10% aq. HCl and NaCl solutions at 35°C and also in boiling water. The percent water uptake, equilibrium time and diffusivity of the composites have been determined and discussed their possible applications.     

Preparation,Mechanical and Electrical Properties of Glass and Jute–Epoxy/Epoxy Polyurethane Composites

Glass and jute (treated and untreated) composites of epoxy resin of 1,1′-bis(3-methyl-4-hydroxy phenyl)cyclohexane(EMC) cured using 20% triethylamine as a hardener (G-EMCT-20 and J-EMCT-20) and EMC- polyurethane of toluene diisocyanate (J-EMCPU and TJ-EMCPU) have been prepared by a hand layup technique under 27.58 MPa pressure and at 150°C for 4 h. G-EMCT-20, J-EMCT-20, J-EMCPU and TJ-EMCPU showed 275, 96.5, 37.3 and 31.5 MPa tensile strength; 351, 84, 10 and 24 MPa flexural strength; 5837, 2758, 1277 and 1619 MPa elastic modulus; 24.6, 7.1, 1.9 and 1.6 kV/mm electric strength; and 1.4 × 10¹³, 1.1 × 10¹¹, 7.7 × 10¹⁰ and 3.6 × 10¹⁰ ohm cm volume resistivity, respectively. Fairly good to excellent mechanical and electrical properties of the composites indicated their industrial applications in building and construction, electrical and electronic industries.     

Hybrid composites from coir fibers reinforced with woven glass fabrics: Physical and mechanical evaluation

Sandwich composites based on coir fiber nonwoven mats as core material were manufactured by Vacuum Assisted Resin Transfer Molding technique. Mechanical and physical properties of produced coir/polyester and coir‐glass/polyester composites were assessed. Samples were evaluated according to their reinforcement contents, resin contents, areal density, and thickness. Tests on physical properties revealed that coir‐glass/polyester sandwich structure has the lowest values of thickness swelling, water absorption and moisture contents compared with coir/polyester composite. Mechanical tests such as tensile strength, open‐hole tensile strength, and flexural strength were also performed on all samples. Coir‐glass/polyester sandwich structure showed significant increase in tensile strength of 70 MPa compared with 8 MPa of coir/polyester composite. Introducing two skins of fiber glass woven roving to coir/polyester increased its flexural strength from 31.8 to 131.8 MPa for coir‐glass/polyester. POLYM. COMPOS., 38:2212–2220, 2017. © 2015 Society of Plastics Engineers     

Synthesis and characterization of epoxy resin of 9,9′-bis-(3,5-dibromo-4-hydroxyphenyl) anthrone-10 and its jute composite

Epoxy resin of 9,9′-bis-(3,5-dibromo-4-hydroxyphenyl) anthrone-10 (EANBr, EEW 490) was synthesized and was characterized by IR and ¹HNMR . EANBr and EPK3251 cured resin (EANBrC) were characterized by DSC and TGA at 10°Cmin^?1 under nitrogen atmosphere. Broad DSC endothermic transitions of EANBr (265.3 °C) and EANBrC (291.4 °C) are due to some physical change and further confirmed by no weight loss in their TG thermograms. EANBr and EANBrC are thermally stable up to 340 °C and 310 °C, respectively. EANBr has followed single step degradation kinetics, while EANBrC has followed two step degradation kinetics. EANBr followed apparently zero order kinetics, while EANBrC followed apparently second order (1.80) and first order (0.89) degradation kinetics, respectively. Ea and A values of EANBrC (299.7 kJmol^?1 and 6.32?×?10²⁰ s^?1) were found higher than that of EANBr (201 kJmol^?1 and 2.45?×?1013 s^?1) due to more rigid nature of EANBrC. The ΔS^* value of the first step degradation of EANBrC (146.3 JK^?1 mol^?1) was found much more than that of EANBr (4.6 JK^?1 mol^?1). Jute – EANBr composite (J-EANBr) was prepared by compression molding technique at 120 °C for 5 h and under 20 Bar pressure. The observed tensile strength, flexural strength, electric strength and volume resistivity of J-EANBr are 24.7 MPa, 19.0 MPa, 1.8 kVmm^?1 and 3.5?×?10¹² ohm cm, respectively. Water absorption in J-EANBr was carried out at 30 ± 2 °C against distilled water, 10% NaCl, 10% HCl, 10% HNO₃, 10% H₂SO₄, 10% NaOH, and 10% KOH and also in boiling water. The equilibrium time and equilibrium water content for J-EANBr in different environments are 384–432 h; 12.7–15.2%, respectively. The observed equilibrium water content and diffusivity trends of J-EANBr are KOH>H₂SO₄>HCl>NaOH>H₂O>NaCl and H₂O>NaCl>NaOH>H₂SO₄>HCl>KOH, respectively. Good thermo-mechanical, electrical properties and excellent hydrolytic stability of J-EANBr may be useful for high temperature applications in diverse fields.     

Fabrication and evaluation of some mechanical and electrical properties of jute‐biomass based hybrid composites

Hybrid composites based on bisphenol‐C‐formaldehyde resin and jute mat with rice, wheat, sugar cane, and jamun husks have been fabricated at 150°C under 30.4 MPa pressure for 2 h. The resin content in composites was 50% of fibers. Tensile strength, flexural strength, electric strength, and volume resistivity of hybrid composites have been evaluated and compared with those of jute‐bisphenol‐C‐formaldehyde composites. It is observed that the tensile strength of composites is found to decrease by 53–72%, which is mainly due to random orientation of sandwiched fibers. Flexural strength has increased by 53–153% except jute–rice husk composite for which it is decreased by 26%. A little change in dielectric breakdown strength (1.89–2.11 kV/mm) is found but volume resistivity of Jute–wheat husk and Jute–jamun husk composites has improved by 437–197% and it is slightly decreased(2.3–25.2%) for the remaining two composites. Thus, hybrid composites possess good mechanical and electrical properties signifying their importance in low strength and light weight engineering applications as well as low cost housing units such as partition and hard boards. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1754–1758, 2006     

Physicochemical Study of CPOL-701–Glass/Jute Composites

Glass and jute composites (CPOL-701-G and CPOL-701-J) have been fabricated by hand lay-up technique at 50°C under 27.6 MPa pressure for 3–4 h using MEKP and cobalt naphthenate. Both composites possess excellent tensile, flexural and dielectric strengths, volume resistivity and dielectric constant as well as hydrolytic stability against water, 10% aq. HCl and 10% aq. NaCl at 35°C. Cured CPOL-701 appears to be having good thermal stability (206°C) and high values of kinetic parameters. Excellent physicochemical properties of the composites signify their industrial importance.     

聚酯预浸料复合SMC工艺及其应用

对以SMC为基础,添加以不饱和聚酯预浸材料作为加强层,形成的复合SMC材料进行了研究,介绍了采用的工艺流程和成型方法;以0.4mm的无碱玻璃布作为加强层增强材料,制作预浸布,以1∶1的体积比与SMC材料复合,采用复合SMC工艺成型的制品机械性能与常规SMC和采用聚酯作为树脂基体的RTM制品性能比较,拉伸强度达到180MPa,弯曲强度达到262MPa,冲击强度达到246kJ/m2,性能优势明显。     

Thermal,Mechanical and Morphological Characterization of Jute/Gelatin Composites

Jute fabrics/gelatin biocomposites were fabricated using compression molding. The fiber content in the composite varied from 20–60 wt%. Composites were subjected to mechanical, thermal, water uptake and scanning electron microscopic (SEM) analysis. Composite contained 50 wt% jute showed the best mechanical properties. Tensile strength, tensile modulus, bending strength, bending modulus and impact strength of the 50% jute content composites were found to be 85 MPa, 1.25 GPa, 140 MPa and 9 GPa and 9.5 kJ/m², respectively. Water uptake properties at room temperature were evaluated and found that the composites had lower water uptake compared to virgin matrix.     

Comparative Studies of Mechanical and Interfacial Properties Between Jute Fiber/PVC and E-Glass Fiber/PVC Composites

Composites (50 wt% fiber) of jute fiber reinforced polyvinyl chloride (PVC) matrix and E-glass fiber reinforced PVC matrix were prepared by compression molding. Mechanical properties such as tensile strength (TS), tensile modulus (TM), bending strength (BS), bending modulus (BM) and impact strength (IS) of both types of composites was evaluated and compared. Values of TS, TM, BS, BM and IS of jute fiber/PVC composites were found to be 45 MPa, 802 MPa, 46 MPa, 850 MPa and 24 kJ/m², respectively. It was observed that TS, TM, BS, BM and IS of E-glass fiber/PVC composites were found to increase by 44, 80, 47, 92 and 37.5%, respectively. Thermal properties of the composites were also carried out, which revealed that thermal stability of E-glass fiber/PVC system was higher. The interfacial adhesion between the fibers (jute and E-glass) and matrix was studied by means of critical fiber length and interfacial shear strength that were measured by single fiber fragmentation test. Fracture sides after flexural testing of both types of the composites were investigated by Scanning Electron Microscopy.     

Influence of PTFE as a solid lubricant on the mechanical,electrical, and tribological properties of CF-reinforced PC composites

The objective of this research was to study the effects of polytetrafluoroethylene (PTFE) as a solid lubricant on the mechanical, electrical, and tribological properties of carbon fiber (CF)-reinforced polycarbonate (PC) composites. Samples were prepared by means of single-screw extrusion and injection molding processes. The mechanical tests included tensile, flexural, and failing weight impact tests, while the electrical tests consisted of surface and volume resistivity tests. The tribological testing was conducted under dry sliding conditions using pin-on-disk configuration. The results showed that the addition of CF managed to significantly reduce the electrical resistivity as the CF loading approached 10–15 wt%. The addition of PTFE managed to reduce the resistivity of the composite, that is, from 4.51 to 0.53 × 10 (Ωcm). The incorporation of 15 wt%. CF resulted with an increase of 45% in tensile strength and 51.5% in flexural strength, while the addition of PTFE had a negative impact on both properties. It was shown that PTFE was able to reduce the friction coefficient, μ and wear rate, K up to 0.257 and 6.35 × 10⁶ (mm³/Nm), respectively, which can be attributed to the excellent abilities of PTFE to form transfer film. The composite consisting of 15 wt% CF and 10 wt%. PTFE showed highest improvement in term of electrical resistivity, and is deemed the most suitable composition for this study. Scanning electron microscopy was also carried out to further elucidate the fracture and wear mechanism of the PC/CF/PTFE composites.     

Electrical and thermal conductivity and tensile and flexural properties of carbon nanotube/polycarbonate resins

Adding conductive carbon fillers to insulating thermoplastic polymers increases the resulting composite's electrical conductivity. Carbon nanotubes (CNTs) are very effective at increasing composite electrical conductivity at low loading levels without compromising composite tensile and flexural properties. In this study, varying amounts (2–8 wt %) of CNTs were added to polycarbonate (PC) by melt compounding, and the resulting composites were tested for electrical conductivity (1/electrical resistivity), thermal conductivity, and tensile and flexural properties. The percolation threshold was less than 1.4 vol % CNT, likely because of CNTs high aspect ratio (1000). The addition of CNT to PC increased the composite electrical and thermal conductivity and tensile and flexural modulus. The 6 wt % (4.2 vol %) CNT in PC resin had a good combination of properties for electrical conductivity applications. The electrical resistivity and thermal conductivity were 18 Ω‐cm and 0.28 W/m · K, respectively. The tensile modulus, ultimate tensile strength (UTS), and strain at UTS were 2.7 GPa, 56 MPa, and 2.8%, respectively. The flexural modulus, ultimate flexural strength, and strain at ultimate flexural strength were 3.6 GPa, 125 MPa, and 5.5%, respectively. Ductile tensile behavior is noted in pure PC and in samples containing up to 6 wt % CNT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical characterization and fractography of glass fiber/polyamide (PA6) composites

The mechanical properties of the glass fiber reinforced Polyamide (PA6) composites made by prepreg tapes and commingled yarns were studied by in‐plane compression, short‐beam shear, and flexural tests. The composites were fabricated with different fiber volume contents (prepregs—47%, 55%, 60%, and commingled—48%, 48%, 49%, respectively) by using vacuum consolidation technique. To evaluate laminate quality in terms of fiber wet‐out at filament level, homogeneity of fiber/matrix distribution, and matrix/fiber bonding standard microscopic methods like optical microscopy and scanning electron microscopy (SEM) were used. Both commingled and prepreg glass fiber/PA6 composites (with V_f ∼ 48%) give mechanical properties such as compression strength (530–570 MPa), inter‐laminar shear strength (70–80 MPa), and transverse strength (80–90 MPa). By increasing small percentage in the fiber content show significant rise in compression strength, slight decrease in the ILSS and transverse strengths, whereas semipreg give very poor properties with the slight increase in fiber content. Overall comparison of mechanical properties indicates commingled glass fiber/PA6 composite shows much better performance compared with prepregs due to uniform distribution of fiber and matrix, better melt‐impregnation while processing, perfect alignment of glass fibers in the composite. This study proves again that the presence of voids and poor interface bonding between matrix/fiber leads to decrease in the mechanical properties. Fractographic characterization of post‐failure surfaces reveals information about the cause and sequence of failure. POLYM. COMPOS., 36:834–853, 2015. © 2014 Society of Plastics Engineers     

Synthesis and properties of fluorinated biphenyl‐type epoxy resin

A novel fluorinated biphenyl‐type epoxy resin (FBE) was synthesized by epoxidation of a fluorinated biphenyl‐type phenolic resin, which was prepared by the condensation of 3‐trifluoromethylphenol and 4,4′‐bismethoxymethylbiphenyl catalyzed in the presence of strong Lewis acid. Resin blends mixed by FBE with phenolic resin as curing agent showed low melt viscosity (1.3–2.5 Pa s) at 120–122°C. Experimental results indicated that the cured fluorinated epoxy resins possess good thermal stability with 5% weight loss under 409–415°C, high glass‐transition temperature of 139–151°C (determined by dynamic mechanical analysis), and outstanding mechanical properties with flexural strength of 117–121 MPa as well as tensile strength of 71–72 MPa. The thermally cured fluorinated biphenyl‐type epoxy resin also showed good electrical insulation properties with volume resistivity of 0.5–0.8 × 10¹⁷ Ω cm and surface resistivity of 0.8–4.6 × 10¹⁶ Ω. The measured dielectric constants at 1 MHz were in the range of 3.8–4.1 and the measured dielectric dissipation factors (tan δ) were in the range of 3.6–3.8 × 10^?3. It was found that the fluorinated epoxy resins have improved dielectric properties, lower moisture adsorption, as well as better flame‐retardant properties compared with the corresponding commercial biphenyl‐type epoxy resins. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Adhesion Improvement of Bio-Based Epoxy in Environmentally Friendly and High-Performance Natural Fiber-Reinforced Composites

Developing robust bio-based epoxy against petroleum-derived epoxy is necessary for environmentally friendly and high-performance natural fiber-reinforced composites. A bio-based vanillin epoxy (VE) is synthesized from the lignin-derived vanillin, and a thermoset resin is prepared after mixing it with a 4,4′-diaminodiphenyl methane (DDM) hardener. Further, it is infused in high-cellulose-containing alkali-treated jute fiber (TJF) mats through a simple approach to enhance the adhesion between the VE-DDM and TJF. Bio-based VE-DDM resin shows better compatibility with TJF than petroleum-derived bisphenol A diglycidyl ether (DGEBA) epoxy. The bio-based VE-DDM/TJF composite demonstrates the T_gis ≈165 °C, tensile strength is ≈83.12 ± 3.80 MPa, and Young's modulus is ≈2.86 ± 0.10 GPa with excellent flexural strength (138.72 ± 3.81 MPa) and flexural modulus (8.01 ± 0.11 GPa). It also shows merits regarding hydrophobicity, reduced water absorption ability, durability, and chemical resistance in an acidic medium. The natural fiber-reinforced VE composites pave the way to produce environmentally friendly and high-performance composites for structural applications.     

Effect of carbon content on electrical,thermal, and mechanical properties of porous SiC ceramics with B4C and C additives

The electrical, thermal, and mechanical properties of porous SiC ceramics with B₄C-C additives were investigated as functions of C content and sintering temperature. The electrical resistivity of porous SiC ceramics decreased with increases in C content and sintering temperature. A minimal electrical resistivity of 4.6 × 10^?2 Ω·cm was obtained in porous SiC ceramics with 1 wt% B₄C and 10 wt% C. The thermal conductivity and flexural strength increased with increasing sintering temperature and showed maxima at 4 wt% C addition when sintered at 2000 °C and 2100 °C. The thermal conductivity and flexural strength of porous SiC ceramics can be tuned independently from the porosity by controlling C content and sintering temperature. Typical electrical resistivity, thermal conductivity, and flexural strength of porous SiC ceramics with 1 wt% B₄C-4 wt% C sintered at 2100 °C were 1.3 × 10^?1 Ω·cm, 76.0 W/(m·K), and 110.3 MPa, respectively.