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.     

Degradation Studies of Thermoplastics Composites of Jute Fiber–Reinforced LDPE/Polycaprolactone Blends

This article reports the fabrication, properties, and degradation studies of jute fiber–reinforced thermoplastic polymers. One of the non-traditional outlets of jute fiber is in the area of fiber-reinforced composites. However, the major drawback associated with the application of jute fiber for this purpose is its high moisture regain. To impart hydrophobicity to the fibers and to concomitantly increase interfacial bond strength, which is a critical factor for obtaining better mechanical properties of composites, jute fibers were treated with benzoylchloride, Y-glycidoxytrimethoxysilane, and neo-alkoxy-tri(N-ethylenediamino)ethyltitanate. Such a treatment resulted in an increase in the diameter and denier of the treated fibers, and deterioration in the mechanical properties was observed. SEM studies revealed an increase in surface roughness after titanate and alkali treatment, which in turn increases interfacial bond strength. A series of low-density polyethylene (LDPE) blends with 5–20% (w/w) of poly(e-caprolactone) (PCL) and with/without treated and untreated jute fibers were prepared by using a single-screw extruder. LDPE modified by blending with PCL (80:20, wt/wt) was used as a thermoplastic matrix. Composites were fabricated by using 1-cm-long jute fibers; the weight fraction of unmodified fibers, silane-treated fibers, and titanate-treated fibers was varied from 0.05 to 0.13. An increase in weight fraction of fibers resulted in an increase in tensile strength and modulus and decrease in elongation at break. Thin sheets and dumbbells were used for enzymatic degradation tests. The degradation of the material was monitored by weight change and loss of mechanical properties. The enzymatic degradation in the presence of Pseudomonas cepacia lipase gave appreciable weight loss in PCL and blended materials.     

Influence of Re-adhesion on the Wear and Friction of Glass Fibre–Reinforced Polyester Composites

Based on the well-known pin-on-disc test rig, a new test setup for online measuring of wear and friction behaviour of polymer matrix composites has been developed. In contrast to a traditional friction-and-wear test rig, a steel pin and composite disc are used for studying the influence of wear debris and fibre orientation. During sliding, a thin adhesive film is possibly formed on the wear track of a composite disc, consisting of wear debris that is squeezed under the steel pin and that finally smoothens onto the composite surface. By optical microscopy, it was observed that most of the debris particles originate from the edges of the wear track. The thin film deforms continuously, with large and dark wear particles observed at the edge of the wear track. A lower coefficient of friction is achieved when the particles are re-adhered to the mating surface. The film formation mechanism depends on the normal force, sliding velocity, and bulk composite structure: because pultruded composite profiles are presently used with a layered structure, a change in film properties is observed depending on the wear depth.     

Studies on Jute Composites—A Literature Review

Jute fiber is an important agricultural product. It is one of the most common natural fibers in Third World countries such as India, China, Bangladesh, etc. The jute industry has special importance in the economy of India and continues to be a major traditional earner of foreign exchange. However, it is facing tough competition from the synthetic fibers. Jute fibers find use in sophisticated fields like decorative and furnishing materials such as lamp shades, wall covers, curtains, upholsteries, etc. Today it is the least expensive fiber of mass consumption, at only a fraction of the cost of glass fibers; in terms of volume, jute is now the second most important fiber in the world, next to cotton. In the traditional applications in carpets, ropes, sacks, etc., jute fibers have been partially replaced by synthetic fibers which have some advantages compared to jute. In order to ensure a reasonable return to farmers, nontraditional outlets have to be explored for the fiber. One such avenue is in the area of fiber-reinforced composites.     

Biodegradation Study of Microcrystalline Chitosan and Microcrystalline Chitosan/β-TCP Complex Composites

Bone repair or regeneration is a common and complicated clinical problem in orthopedic surgery. The importance of natural polymers, such as microcrystalline chitosan, and minerals such as HAp and β-TCP, has grown significantly over the last two decades due to their renewable and biodegradable source, increasing the knowledge and functionality of composites in technological and biomedical applications. This study compares the biodegradation process, bioactivity, structure, morphology, and mechanical properties of microcrystalline chitosan and microcrystalline chitosan/β-TCP complex; the latter according to the new method of preparation. The complex showed a homogeneous network structure with regular pores, good bioactivity, even after 60 days of conducting the hydrolytic and enzymatic degradation process, showing a bacteriostatic and bactericidal activity. The complex indicates that it could be used successfully as a base for implants and scaffolds production in orthopedic surgery.     

Nanoarchitectonics of Enzyme/Metal–Organic Framework Composites for Wastewater Treatment

Journal of Inorganic and Organometallic Polymers and Materials - Metal–organic frameworks (MOFs) provide advantages as supporting materials for the immobilization of enzymes due to their...     

Time–Temperature-Transformation Cure Diagram of Multiwall Carbon Nanotube/Epoxy Composites

This work describes the effects of multiwall carbon nanotube on the isothermal time–temperature-transformation cure diagram to obtain a comprehensive cure map for a 2 wt% multiwall carbon nanotube/epoxy composite. The viscoelastic and thermal properties of the nanocomposites for a wide range of isothermal cure temperatures were obtained using a strain-controlled rheometer ARES TA and a differential scanning calorimetry. The thermal and rheological analyses were used to investigate the vitrification and the gelation of the nanocomposite, and to draw the time–temperature-transformation diagram. This diagram is completed by adding the iso-viscosity curves.     

Jute Fiber Composites from Coal,Super Clean Coal,and Petroleum Vacuum Residue–Modified Phenolic Resin

Jute fiber composites were prepared with novolac and coal, phenolated-oxidized super clean coal (POS), petroleum vacuum residue (XVR)–modifiedphenol-formaldehyde (novolac) resin. Five different type of resins, i.e., coal, POS, and XVR-modified resins were used by replacing (10% to 50%) with coal, POS, and XVR. The composites thus prepared have been characterized by tensile strength, hardness, thermogravimetric analysis (TGA), Fourier-transfer infrared (FT-IR), water absorption, steam absorption, and thickness swelling studies. Twenty percent POS-modified novolac composites showed almost the same tensile strength as that of pure novolac composites. After 30% POS incorporation, the tensile strength decreased to 25.84 MPa from 33.96 MPa in the case of pure novolac resin composites. However, after 50% POS incorporation, the percent retention of tensile strength was appreciable, i.e., 50.80% retention of tensile strength to that of pure novolac jute composites. The tensile strength of coal and XVR-modified composites showed a trend similar to that shown by POS-modified novolac resin composites. However, composites prepared from coal and XVR-modified resin with 50% phenol replacement showed 25.4% and 42% tensile strength retention, respectively, compared to that of pure novolac jute composites. It was found that the hardness of the modified composites slightly decreased with an increase in coal, POS, and XVR incorporation in the resin. The XVR-modified composites showed comparatively lower steam absorption than did coal or POS-modified composites. The thermal stability of the POS-modified composites was the highest among the composites studied. The detailed results obtained are being reported.     

Mechanical and Abrasive Wear Studies on Biobased Jatropha Oil Cake Incorporated Glass–Epoxy Composites

An investigation was made to evaluate the effect of the incorporation of jatropha oil cake (JOC) alone and in combination with silicon carbide (SiC) on the mechanical and tribological wear behaviour of glass fabric–epoxy (GE) composites. A vacuum-assisted resin transfer moulding (VARTM) technique was employed to obtain a series of GE composites containing different fillers viz., silicon carbide, jatropha oil cake and a mixture of SiC and JOC. The effect of different loads (22 and 32 N) and abrading distances from 135 to 540 m on the performance of the wear resistance of the composites were measured. The mechanical properties such as tensile behaviour and hardness of the composites were evaluated. A linear relationship was found between the wear volume loss and the abrading distances. The JOC filled GE composite exhibited a lower specific wear rate by 6 and 10% at 540 m abrading distance for a load of 22 and 32 N, respectively, as compared to that of unfilled GE composites. The worn surface features of unfilled and filled GE composites were examined using scanning electron microscopy (SEM).     

Glass–Ceramic Foams from Borosilicate Glass Waste

In this study, we reported the studies on a glass–ceramic foam with wollastonite and cristobalite micrometric crystals prepared by sintering a borosilicate glass waste with organic binder as foaming agent. The waste glass, coming from the dismantling of washing machine, was characterized by high CaO content and low-temperature sinterability. The effect of the temperature on the sinter-crystallization ability of the borosilicate glass waste was followed with thermal analysis, heating microscopy, and electron scanning microscopy (ESEM) observations. Additionally, the effect of temperature on the evolution of crystalline phases and density variation was monitored with XRD and density measurements. The softening started at 800°C and crystallization at 845°C to be completed at 900°C with a linear expansion of 38–40% in the range 850–900°C. Wollastonite and cristobalite were identified as crystalline phases in variable proportions dependently upon temperature. No crack evidence was found at high ESEM magnification even though cristobalite crystals were present. The final products showed a total porosity around 78–79% and an apparent density of about 0.5 g/cm³, in line with common porous closed-cell glass foams used for thermal insulation.     

Crystallization Behaviors of Graphene Oxide–Carbon Nanotubes Hybrids/Polyamide 66 Composites

The crystallization behaviors of graphene oxide–carbon nanotube hybrids/polyamide 66 composites were characterized by using differential scanning calorimetry. The results of nonisothermal crystallization showed that the halftime of crystallization and crystallization enthalpy increased with an increase in filler loading. The results of isothermal crystallization showed that the halftime of crystallization was affected not only by the filler loading but also the crystallization temperature. Moreover, it decreased with an increase in filler loading at 243°C, while decreased first and then increased at 245 or 247°C. In addition, when the filler loading was 0.6?wt%, it reached the minimum value. This was the same as the isothermal crystallization activation energy.     

Tailoring the Microstructure of Sol–Gel Derived Hydroxyapatite/Zirconia Nanocrystalline Composites

In this study, we tailor the microstructure of hydroxyapatite/zirconia nanocrystalline composites by optimizing processing parameters, namely, introducing an atmosphere of water vapor during sintering in order to control the thermal stability of hydroxyapatite, and a modified sol–gel process that yields to an excellent intergranular distribution of zirconia phase dispersed intergranularly within the hydroxyapatite matrix. In terms of mechanical behavior, SEM images of fissure deflection and the presence of monoclinic ZrO₂ content on cracked surface indicate that both toughening mechanisms, stress-induced tetragonal to monoclinic phase transformation and deflection, are active for toughness enhancement.     

Evaluation of Physicochemical and Antifungal Properties of Polylactic Acid–Thermoplastic Starch–Chitosan Biocomposites

Biocomposites of polylactic acid, thermoplastic starch, chitosan powder, and chitosan lyophilized powder were prepared using an extrusion process. The color, thermal, structural, mechanical, morphology, and antimicrobial properties were evaluated. The addition of thermoplastic starch and chitosan (chitosan powder and chitosan lyophilized powder) produced significant changes in color and heterogeneous surface morphology of the polylactic acid biocomposites. The thermal, mechanical, and morphometric properties of the material showed changes with the addition of thermoplastic starch and chitosan (chitosan powder and chitosan lyophilized powder). The biocomposites formulated with chitosan powder and chitosan lyophilized powder showed antifungal activity when evaluating this property. The biocomposites produced could be used in packaging applications.     

Physicochemical Study of Glycerol Hydrogenolysis Over a Ni–Cu/Al2O3 Catalyst Using Formic Acid as the Hydrogen Source

Glycerol hydrogenolysis to propanediols requires the use of hydrogen as reactant. One interesting option is to directly generate this hydrogen in active sites of the support using hydrogen donors, such as formic acid. The effect that the reacting pressure has on glycerol conversion and product selectivity over a Ni–Cu/Al₂O₃ catalyst was studied. The negative effect of decreasing the pressure was much more significant when the source of hydrogen was dissolved molecular hydrogen than when it was formic acid. X-ray photoelectron spectroscopy and temperature programmed reduction measurements were performed to understand the effect of Ni–Cu/Al₂O₃ reduction procedure on the catalytic activity. Semi-batch reactor studies with the Ni–Cu/Al₂O₃ catalyst were carried out with continuous addition of the hydrogen donor to obtain kinetic data. Langmuir–Hinshelwood type models were developed to describe the direct conversion of glycerol into propanediol, and propanediol further hydrogenolysis to 1-propanol. The model included the competitive adsorption between both glycols. These models were used to obtain valuable data for the optimization of the process.     

Thermal Conductivity of a Glass: I. Measurement by the Glass–Metal Contact

The thermal (phonon) conductivity of glass has been measured by contacting the sample with a metal at a different uniform initial temperature. The subsequent temperature response in the metal is measured by a tiny thermocouple just underneath the (contact) surface. The coefficient of heat penetration c _p follows directly from the fitted asymptotic temperature jump or drop for long times. Division by the separately measured heat capacity c _p yields the thermal conductivity . The conductivity measurement reproducibility was = 3%. The standard deviation between validation measurements and round robin test results on Pyrex glass was = 5.8%, somewhat more than the accuracy = 5.2% of the round robin test results. The measurement method is insensible for slight imperfections of the thermal contact and infrared radiation diffusion (photon conductivity) in a hot glass. The method has been used with minor modifications for solid and molten samples at temperatures of 50–850°C and conductivities of 0.1–25 W/(m K). The thermal (phonon) conductivity of the investigated soda-lime silicate glasses increases slightly (27–30%) with temperature from ambient up to around the glass transition.     

Modeling Reaction–Diffusion Processes of the Formation of Diamond–Silicon Carbide Composites

Glass Physics and Chemistry - In this study, for the first time, the reaction–diffusion processes providing the formation of a composite diamond–silicon carbide material, which has a...     

Use of an Optical–Mechanical Test Combined with Acoustic-Emission Techniques to Study Adhesion in Filled Polymeric Composites

The use of acoustic-emission (AE) techniques integrated with single-particle composite (SPC) mechanical–optical testing is proposed to evaluate and characterize adhesion in particle-filled polymeric composites. It is shown that not only can an intrinsic interfacial strength be determined but also that different types of adhesion mechanisms may be distinguished in terms of straightforward criteria using the wavelet transform (WT) of the acoustic signature, once problems with internal reflections in the test coupon are resolved. The validity of the proposed method is demonstrated with a study of the adhesion of a commercial poly(vinylbutyral) (PVB) to bare and aminosilane-treated glass beads.     

Effect of Saturated/Unsaturated Fatty Acid Ratio on Physicochemical Properties of Palm Olein–Olive Oil Blend

Although blending polyunsaturated oil with more saturated or monounsaturated oils has been studied extensively, there is no similar information regarding the partial replacement of palm olein with olive oil (OO). Therefore the main objective of this study was to investigate the effects of OO partial replacement (0, 25, 50, 75, 90 and 100% w/w) on the chemical stability of palm olein oil (POO). The physicochemical properties of oil samples namely iodine value, peroxide value (PV), anisidine value, TOTOX value (total oxidation value, TV), free fatty acid (FFA), cloud point, color and viscosity were considered as response variables. Significant differences among the oil blend properties were determined at the significance level of P < 0.05. Apart from FFA, all the response variables were significantly influenced by type and concentration of oils. The oil blend containing 10% POO and 90% OO showed the highest TV (6.10); whereas the blend containing 90% POO and 10% OO exhibited the least TV (2.41). This study indicated that the chemical stability of oil blend significantly (P < 0.05) increased with increasing the proportion of polyunsaturated/monounsaturated fatty acid.     

Nanoindentation of Soda Lime–Silica Glass: Effect of Loading Rate

Structural and mechanical reliability of glass for both conventional and advanced applications is determined by the rate at which it can deform and sustain externally applied static or dynamic strain at the microstructural length scale. Hence, a large number of nanoindentation experiments were conducted on a thin (∼300 μm) commercial soda lime–silica glass with a 150 nm radius Berkovich tip at a constant load of 10,000 μN as a function of variations in the loading rates in the range of 10–20,000 μN/s. The results showed that the nanohardness of the soda lime–silica glass increased by as much as 74% as the loading rate was increased from 10 to 20,000 μN/s. Further, the presence of serrations in load–depth plots and deformation band formations inside the nanoindentaion cavities were more vividly observed in the nanoindentation experiments conducted at lower loading rates rather than those conducted at higher loading rates. These results are explained in terms of shear stress acting underneath the indenter as well as the time scale of interaction between the nanoindenter and the weak links at local microstructural length scale, which owe their origin to the subtle variations in the composition of the given glass.