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.     

Porosity Defect Morphology Effects in Carbon Fiber – Epoxy Composites

This study examines the morphology of porosity defects and the effects on the flexural stiffness of prepreg produced carbon fiber/epoxy matrix composites. In this study, an analytical and experimental effort is presented for assessing the effects of porosity on the flexural rigidity. The analytical approach for predicting the flexural rigidity is based on a transformed cross-section of the original laminate. Specimens of carbon/epoxy multi-layered specimens are manufactured with void contents in the range of 1 to 25% for calibration and validation of the proposed data. Significant improvements in flexural rigidity are correlated with higher porosity and thickness measurements.     

BaTiO3–Epoxy Composites for Electronic Applications

A brief review related with dielectric properties of BaTiO₃/epoxy composites is presented. The composites were obtained using the dipping technique. To facilitate the mixing and modify the filler surface, a solvent and a surface coupling agent were used. Intermediate and low concentrations of solvent and silane improved microstructure and dielectric properties of the composite material, whereas higher concentrations led to composites of poor quality. Finally, a model using finite elements was used, in order to predict the composite permittivity in relation to the percentage of filler. Model results were compared with the effective medium theory and experimental results.     

Polymer–Ceramic Composites of 0–3 Connectivity for Circuits in Electronics: A Review

Composite technology, where a novel artificial material is fabricated by combining, for example, ceramic and polymer materials in an ordered manner or just by mixing, was earlier used widely for sonar, medical diagnostics, and NDT purposes. However, in recent decades, large numbers of ceramic–polymer composites have been introduced for telecommunication and microelectronic applications. For these purposes, composites of 0–3 connectivity (a three-dimensionally connected polymer phase is loaded with isolated ceramic particles) are the most attractive from the application point of view. Composites of 0–3 connectivity enable flexible forms and very different shapes with very inexpensive fabrication methods including simply mixing and molding. In this brief review, we gather together the research carried out within 0–3 ceramic–polymer composites for microwave substrates, also including embedded capacitor, inductor, or microwave-absorbing performances.     

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.     

An Intumescent-Like Flame-Retardant Effect of Hollow Carbon Precursor on Acrylonitrile–Butadiene–Styrene/Oligomeric Aryl Phosphate/Novolac Epoxy Composites

An intumescent-like char layer was formed by introducing hollow phenolic microspheres into acrylonitrile–butadiene–styrene/oligomeric aryl phosphate/novolac epoxy resin. Acrylonitrile–butadiene–styrene-grafted maleic anhydride was used to improve their compatibility. Combustion and thermal degradation behaviors were studied. The results showed that the ABS composites containing 25 wt% oligomeric aryl phosphate/novolac epoxy (3/2) obtains a limiting oxygen index as high as 50; however, it cannot be classified in the UL-94 test. Combination of oligomeric aryl phosphate/novolac epoxy, acrylonitrile–butadiene–styrene-grafted maleic anhydride, and hollow phenolic microspheres (23/10/2) improves the UL-94 grade of acrylonitrile–butadiene–styrene composites to V-1. A continuous and compact porous intumescent-like char layer is generated during combustion; thus, better flame retardancy is obtained.     

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.     

Processing and Characterisation of Epoxy–SiC Functionally Graded Polymer Matrix Composites

This paper proposed preparing and investigating the Epoxy–Silicon carbide composite for aerospace applications. In recent years aerospace industries concentrated in low weight, high strength and high thermal resistance materials. Polymer matrix composite can provide a better solution for the statement mentioned above. This study thermosetting study Epoxy and SiC materials have mixed in centrifugal casting with the ratio of 5%-SiC and resin. The microstructural evaluation is carried by Scanning Electron microscopic and investigating the tensile and hardness properties of the Epoxy– SiC Functionally Graded Polymer Matrix Composites. The wear and fracture analyse were investigated, and the results were discussed. the results show the SiC has provided the higher strength for composite, and its mixing percentage has control the weight of the polymer composite.

     

Polyaniline–Carbon Nanotube Composites: Preparation Methods,Properties, and Applications

Synthesis of polyaniline and hybrid carbon nanotube reinforced polyaniline nanocomposites by various methods has discussed in this review. Different routes used for functionalization of carbon nanotube have been reported. The electrical, mechanical, and thermal properties of polyaniline/carbon nanotube nanocomposites are also discussed. The dispersion of functionalized carbon nanotube, filler concentration, and their alignment in the interior of polyaniline matrix affect their morphology. Furthermore, article focussed upon the various morphologies of polyaniline and polyaniline/carbon nanotube nanocomposites obtained with different methods along with electrical conductivity. Possible applications of polyaniline/carbon nanotube nanocomposites in the areas of actuators, sensors, electromagnetic interference shielding have also discussed.     

Nondestructive Evaluation (NDE) for Characterizing Oxidation Damage in Cracked Reinforced Carbon–Carbon

In this study, coated reinforced carbon–carbon (RCC) samples of similar structure and composition as that from the NASA space shuttle orbiter's thermal protection system were fabricated with slots in their coating simulating craze cracks. These specimens were used to study oxidation damage detection and characterization using nondestructive evaluation (NDE) methods. These specimens were heat treated in air at 1143°C and 1200°C to create cavities in the carbon substrate underneath the coating as oxygen reacted with the carbon and resulted in its consumption. The cavities varied in diameter from approximately 1 to 3 mm. Single-sided NDE methods were used because they might be practical for on-wing inspection, while X-ray micro-computed tomography (CT) was used to measure cavity sizes in order to validate oxidation models under development for carbon–carbon materials. An RCC sample having a naturally cracked coating and subsequent oxidation damage was also studied with X-ray micro-CT. This effort is a follow-on study to one that characterized NDE methods for assessing oxidation damage in an RCC sample with drilled holes in the coating.     

Silica-Based Ziegler–Natta Catalysts: A Patent Review

Silica-based Ziegler–Natta catalysts are important industrially in the manufacture of polyethylene and polypropylene. They are scientifically very interesting because of the complex effects of porous silica on catalyst performance. This patent review explains how silica–based Ziegler–Natta catalysts are related to Phillips chromium–silica catalysts and explores their value for the gas phase and slurry processes for the manufacture of polyolefins. The subcategories dealt with are the following: magnesium–titanium–silica catalysts, which are valuable for high-density polyethylene, for the ethylene copolymers called linear low-density polyethylene;and ethylene–propylene rubber, and for isotactic polypropylene; vanadium–silica catalysts, which are useful in the polymerization and copolymerization of ethylene; and vanadium plus titanium–silica catalysts which often exhibit reactivity synergism. Dual-site and multisite catalysts are also reviewed.     

Thermal Properties of Carbon Nanotube–Copper Composites for Thermal Management Applications

Carbon nanotube–copper (CNT/Cu) composites have been successfully synthesized by means of a novel particles-compositing process followed by spark plasma sintering (SPS) technique. The thermal conductivity of the composites was measured by a laser flash technique and theoretical analyzed using an effective medium approach. The experimental results showed that the thermal conductivity unusually decreased after the incorporation of CNTs. Theoretical analyses revealed that the interfacial thermal resistance between the CNTs and the Cu matrix plays a crucial role in determining the thermal conductivity of bulk composites, and only small interfacial thermal resistance can induce a significant degradation in thermal conductivity for CNT/Cu composites. The influence of sintering condition on the thermal conductivity depended on the combined effects of multiple factors, i.e. porosity, CNTs distribution and CNT kinks or twists. The composites sintered at 600°C for 5 min under 50 MPa showed the maximum thermal conductivity. CNT/Cu composites are considered to be a promising material for thermal management applications.     

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.     

High Stiffness Natural Fiber‐Reinforced Hybrid Polypropylene Composites

Abstract

Natural fibers are potentially a high‐performance non‐abrasive reinforcing fiber source. In this study, pulp fibers [including bleached Kraft pulp (BKP) and thermomechanical pulp (TMP)], hemp, flax, and wood flour were used for reinforcing in polypropylene (PP) composite. The results show that pulp fibers, in particular, TMP‐reinforced PP has the highest tensile strength, possibly because pulp fibers were subjected to less severe shortening during compounding, compared to hemp and flax fiber bundles. Maleic‐anhydride grafted PP (MAPP) with high maleic anhydride groups and high molecular weight was more effective in improving strength properties of PP composite as a compatiblizer. Coupled with 10% glass fiber, 40% TMP reinforced PP had a tensile strength of 70 MPa and a specific tensile strength comparable to glass fiber reinforced PP. Thermomechanical pulp was more effective in reinforcing than BKP. X‐ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used to aid in the analysis. Polypropylene with high impact strength was also used in compounding to improve the low‐impact strength prevalent in natural fiber‐reinforced PP from injection molding.     

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).     

Electromagnetic Interference Shielding of Polymer/Nanodiamond,Polymer/Carbon Nanotube,and Polymer/Nanodiamond–Carbon Nanotube Nanobifiller Composite: A Review

In this review, properties and potential of carbon nanotube, nanodiamond, and nanodiamond–carbon nanotube hybrid nanobifiller have been discussed with reference to electromagnetic interference shielding materials. The nanodiamond and carbon nanotube nanofiller and nanodiamond–carbon nanotube nanobifiller have outstanding electrical, thermal, and mechanical features. Main focus of review was electromagnetic interference shielding phenomenon and its implication in polymer/nanodiamond, polymer/carbon nanotube, and polymer/nanodiamond–carbon nanotube nanobifiller composite. The epoxy/nanodiamond, epoxy/carbon nanotube, and epoxy/nanodiamond–carbon nanotube composites have been discussed with electromagnetic interference shielding shielding features. Thus, considerable enhancement in electromagnetic interference shielding shielding features was observed using higher nanodiamond, carbon nanotube, and nanodiamond–carbon nanotube loadings. Significance and future potential of these polymeric composite are specified.     

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.     

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.     

Effect of Processing Conditions on Adhesion Performance of a Sol–Gel Reinforced Epoxy/Aluminum Interface

The Boeing sol–gel process (Boegel-EPII) is a surface preparation method for metallic substrates for adhesive bonding and painting applications. This paper describes an investigation into the effect of processing conditions on adhesion strength and durability of a sol–gel reinforced, rubber toughened epoxy/aluminum joint. Using an asymmetric double cantilever beam (ADCB) wedge test, the adhesion performance of the sol–gel reinforced epoxy/aluminum joint in a humid environment was measured as a function of sol–gel processing conditions. The sol–gel drying time, concentration and drying humidity all have an effect on adhesion performance. Prolonged drying led to a decrease in fracture energies. The critical and threshold fracture energies show different trends as sol–gel concentration varies, and better adhesion performance was observed for sol–gel dried at higher humidity compared to lower humidity. The failure modes and mechanisms were studied by XPS and SEM. Analysis of locus of failure revealed that the observed trends for adhesion performance can be explained in terms of interdiffusion of the sol–gel film and epoxy. The diffusion of the epoxy into the sol–gel layer is hypothesized to strongly depend on the degree of condensation of the sol–gel film and is directly affected by the sol–gel processing conditions.     

Composites of Poly(Keto-Sulfide)–Epoxy Resin Systems and Their Thermal and Mechanical Properties

A novel matrix resin system, poly(keto-sulfide)–epoxy resin, has been developed. The poly(keto-sulfide)s (PKS), based on various ketones, formaldehyde, and sodium hydrogen sulfide (NaSH), were prepared by the reported process. These (PKS) having terminal thiol (–SH) groups were used for curing commercial epoxy resin (i.e., diglycidyl ether of bisphenol A – DGEBA), to fabricate crosslinked epoxy-poly(keto-sulfide) resin glass fiber-reinforced composites (GRC). Various epoxy/hardener (PKS) mixing ratios were used, and the curing of epoxy-PKS has been monitored using differential scanning calorimetry (DSC) in dynamic mode. Based on DSC parameters the GRC of epoxy-PKS were prepared and characterized by thermal and mechanical methods. The variation in resin/hardener ratio led to variations in thermal and mechanical properties.