Processing and Characterization of Hybrid Nanoparticle Infused Structural Fiber Composites

In this study, nanoalumina (Al2O3) and nanosilica (SiO2) particles are evaluated as tougheners for a high glass-transition temperature (Tg) epoxy system in correlation with liquid composite molding (LCM) processability. The aim of this paper is to directly compare the effectiveness of nanoalumina and nanosilica of the same nominal particle size as epoxy tougheners on the same neat resin system. The epoxy resin system used in this study was Dow D.E.R. 330 amine cured epoxy with a Tg of 150℃. Both particle types are observed to be Tg neutral and increase fracture toughness of the base epoxy system. Between the two particle types, nanoalumina is found to be more effective than nanosilica in terms of achievable fracture toughness at a given particle loading. As resin viscosity increases with particle addition, the addition of fewer particles with the use of nanoalumina is also beneficial to LCM processing where a lower viscosity is preferable.

The goal of this research project was to evaluate and compare the effect of fabric architecture on the processing and properties of composites made by Vacuum Assisted Resin Transfer Molding (VARTM). The fabric architectures investigated included plain weave, satin weave, and warp-knit unidirectional. The fiber types included E-glass and standard modulus carbon fiber. Flat panels were fabricated with a lab scale VARTM process using an epoxy resin system. Fabric plies were cut to 45 cm x 30 cm (18 in. x 12 in.), and the number of plies used depended on the fiber areal weight of each fabric to produce panels of similar final thickness. The speed of resin infusion was recorded by visually monitoring the flow front which was visible through the bag. Fiber volume fraction was evaluated using thickness measurements, and porosity was investigated via optical microscopy. Mechanical testing was performed via tensile and 3-point flexure. The results showed the fabric type had minimal effect on the infusion speed with the exception of the plain weave and satin weave fiberglass. From the mechanical testing results, there are many comparisons made of the modulus, strength, and strain-to-failure results, for example carbon vs. glass, unidirectional vs. woven, tensile vs. flexure. The rule of mixtures was able to predict some but not all of these properties. The results, which are discussed in detail herein, illustrate the main advantage of selecting carbon vs. glass in stiffness driven applications.

Carbon nanotubes and carbon nanofibers have been used as nanofillers for high performance damping composite materials in recent years. The large specific area (1000 m2/g) and aspect ratio (>1000) of carbon nanotubes and nanofibers promote significant interfacial friction between carbon nanotubes/nanofibers and the polymer matrix. The high stiffness and strength of carbon nanotubes and nanofibers enlarge the differences in the strains of individual constituents of the composites, which causes much higher energy dissipation in the polymer matrix. However, adding small amount of carbon nanotubes and nanofibers will significant increase the viscosity of polymer resin, which makes the dispersion and resin flow through the porous fiber mats extremely difficult. In addition, the fiber mats will filter carbon nanotubes and nanofibers during liquid molding process such as Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). A unique concept of manufacturing nanocomposites with carbon nanotube/nanofiber based nanopaper sheets for structural damping applications has recently been explored. This approach involves making carbon nanopaper sheet by the filtration of well-dispersed carbon nanotubes and carbon nanofibers under controlled processing conditions. Subsequently, carbon nanopaper sheets are integrated into composite laminates using Vacuum Assisted Resin Transfer Molding (VARTM) process. In this study, several nanocomposite plates were fabricated with carbon nanopaper sheet as surface layer. For the comparative study, the regular composite plates without carbon nanopaper sheet were also fabricated. To identify the damping characteristics of each specimen, the Frequency Response Function (FRF) was estimated by a pair of piezoceramic patches: one as an actuator to excite the specimen and the other as a sensor to detect the induced vibrations. From the FRF, the damping ratio of the specimen at each modal frequency of interests was calculated. The experimental results clearly show a significant improvement of damping properties of nanocomposites plates. This research demonstrates structural damping enhancement via carbon nanopaper sheets and provided basic understanding of the damping characteristics for the optimal design and fabrication of high performance damping composites, which have the potential to be used as structural components for many applications.

This study demonstrates the adaptability of ExxonMobil’s Proxxima™ R3630 C32 resin system in converting epoxy-based vacuum-assisted resin transfer molding (VARTM) process to polydicyclopentadiene (pDCPD) resin for scalable production of Class-A automotive parts. The Concept8 domed frunk, developed by Nowicki Autosport Design and fabricated by McCLARIN Composites, successfully transitioned form an OE-grade 3K twill carbon fiber and epoxy resin to a pDCPD-based solution using the same tooling and process. This resulted in the first commercially available Class-A reinforced automotive part for a passenger sports car using pDCPD resin system. The polyolefin thermoset resin system, with lower viscosity and density than conventional epoxy resins, enhances infusion efficiency, reduces cycle times, and lowers component weight for improved performance. Quantitative comparisons show reduced cycle times, improved infusion rates, and weight savings compared to incumbent materials. Future work will integrate pDCPD into high-speed transfer molding (RTM) process to enable high-volume production of structural composite components, further optimizing efficiency, performance, and scalability, positioning pDCPD as a key solution for next-generation automotive composites.

Multi-functional solvent-free SiO2 nanofluid simultaneously improve major properties and fluidity of epoxy resin: A new strategy beyond nanofillers

Vacuum-assisted resin transfer molding (VARTM) process is the most effective solution for composite product manufacturing industries. It allows the manufacturing of large components at a lower cost. VARTM process is most suitable with porous reinforcements such as fiber mat, woven fabric, or knitted fabrics. For fiber-reinforced composite components, the fiber orientation has a great influence on mechanical properties. The objective of this work is to examine the effect of fiber orientation and the number of layers on tensile and flexural strength. The carbon fiber-reinforced composites are prepared using the VARI process. In this experimental study, epoxy-based composite laminates were prepared with orientations, [0o], [90o], [0o/90o], [±45o]. The effect of number of layers was also examined. From the result of tensile testing, the highest tensile strength value was observed at [0o] with seven-layered laminate. From the result of flexural testing, the highest flexural strength value was observed at [0o/90o] with three-layered laminate. It was observed that the tensile property of the laminates was superior when more number of fibers were in alignment with the loading axis. The high bending resistance was observed at [0°/90°] orientation.

Multi-site impact response of S2-glass/epoxy composite laminates

Tailoring surface anisotropy in ternary NiC/glass/epoxy laminates by magnetic field

Vacuum-assisted resin transfer molding (VARTM) has several inherent shortcomings such as long mold filling times, low fiber volume fraction, and high void content in fabricated laminates. These problems in VARTM mainly arise from the limited compaction of the laminate and low resin pressure. Pressurized infusion (PI) molding introduced in this paper overcomes these disadvantages by (i) applying high compaction pressure on the laminate by an external pressure chamber placed on the mold and (ii) increasing the resin pressure by pressurizing the inlet resin reservoir. The effectiveness of PI molding was verified by fabricating composite laminates at various levels of chamber and inlet pressures and investigating the effect of these parameters on the fill time, fiber volume fraction, and void content. Furthermore, spatial distribution of voids was characterized by employing a unique method, which uses a flatbed scanner to capture the high-resolution planar scan of the fabricated laminates. The results revealed that PI molding reduced fill time by 45%, increased fiber volume fraction by 16%, reduced void content by 98%, improved short beam shear (SBS) strength by 14%, and yielded uniform spatial distribution of voids compared to those obtained by conventional VARTM.

Vacuum-Assisted Resin Transfer Molding (VARTM) process was used to fabricate the nanocomposites through integrating carbon nanofiber paper into traditional glass fiber reinforced composites. The carbon nanofiber paper had a porous structure with highly entangled carbon nanofibers and short glass fibers. In this study, the carbon nanofiber paper was employed as an inter-layer and surface layer of composite laminates to enhance the damping properties. Experiments conducted using the nanocomposite beam indicated up to 200-700% increase of the damping ratios at higher frequencies. The scanning electron microscopy (SEM) characterization of the carbon nanofiber paper and the nanocomposites was also conducted to investigate the impregnation of carbon nanofiber paper by the resin during the VARTM process and the mechanics of damping augmentation. The study showed a complete penetration of the resin through the carbon nanofiber paper. The connectivities between carbon nanofibers and short glass fibers within the carbon nanofiber paper were responsible for the significant energy dissipation in the nanocomposites during the damping tests.

Composite structures utilized in defence and aerospace applications might be subjected to impacts due to bird strike, tool dropping and bullet penetration. One of the approaches to this problem is to add nano tubes and nano particles to resin systems in order to improve bonding between fibres and matrix materials. Different nano-particles or nano-tubes of clays, alumina, silica, carbon and graphene have been analysed in composite systems in the literature so far because of the improved mechanical properties. In this study, the low velocity impact behaviour of the aramid fibre reinforced epoxy composite plates, containing two new nano-particles of TiC and ZrC which are not studied formerly, are searched experimentally. After the low velocity impact tests, it is concluded that plates containing titanium carbide nano-particles and zirconium nano-particles yielded 19 % and 4 % respectively less penetration in comparison with particle free plates. In other words, titanium carbide nano-particles contained plates showed more resistance against the impact by 19 % against to particle free plates. These results showed that TiC and ZrC nano particles might be also good contributors for the impact resistance of composite structure.

We report the fatigue behavior of a novel multiscale fiberglass/epoxy composite modified with reduced-graphene oxide (rGO) and graphene nanoplatelets (GNP). A novel and cost-effective fabrication method based on vacuum assisted resin transfer molding (VARTM) method was used for manufacturing the composite laminates. Morphological and mechanical analysis of composites showed a successful dispersion of nano-fillers and a remarkable improvement in fatigue life of the nanocomposites. The experimental results revealed that all rGO concentrations resulted in a significant increase in fatigue life of the nanocomposites. These enhancements can be explained by the creation of stronger links between the nanoparticles fiberglass and epoxy. The experimental results also showed that lower concentrations of GNPs lead to an increase in fatigue life of nanocomposites; however, a decrease in their fatigue life can be seen at higher loadings.

The incorporation of multi-wall carbon nanotubes at weight fractions of 0.5% wt. and 1% wt. in a PRIMASET cyanate ester system (PT-30) was examined. The thermo-mechanical and electrical properties of the developed nanopolymers were investigated and were compared with the neat matrix properties. A preparation method was developed for the incorporation of the fillers in the resin system. The phenomenon of re-agglomeration of nanotubes took place in the first stages of curing schedule but nevertheless according to the SEM images a good dispersion was generally achieved. DSC, DMA, TGA and thermal conductivity tests were performed for the thermal characterization. For the electrical characterization, AC and DC measurements took place. No significant change in the glass transition temperature (Tg), thermal conductivity and mass loss values was observed in comparison with the neat resin systems. However, in both cases the improvement of electrical conductivity was about nine orders of magnitude, indicating that percolation had been achieved. The elastic modulus in bending was examined and a slight increase was observed in direct comparison with the neat resin. Finally, the developed doped nanopolymer was used as matrix for the CFRPs manufacturing. A full manufacturing protocol was developed in order to overcome the challenging issues concerning the cyanate esters' handling and manufacturing processes. Moreover AC and DC measurements were performed along with thermal conductivity measurements and TMA. The produced modified composites were tested for short beam strength.

Vinyl ester BisGMA [Bisphenol-A-glycidyldimethacrylate] resin has been modified by incorporating Titanium dioxide(TiO2)nanoparticles (0.5%-2% by weight). An ultrasonic mixing process was employed to disperse the particles into the resin system prior to casting and curing test specimens. From TEM investigation, it is found that the particles are nano size (5-60nm) and dispersed throughout the entire volume of the resin. Dynamic mechanical analysis was conducted for both the neat resin and nanocomposite. In dynamic mechanical analysis, nanocomposite shows increase in storage modulus (6%), and glass transition temperature (5.8%) from neat resin system. Thermogravimetric analysis shows 7.5% better thermal stability. In addition, the nanocomposite shows enhance in the stiffness by 5% in flexural loading. The Tg and flexural modulus of the nanocomposites were enhanced as the particle volume fraction was enhanced and than decreased.

Well RXY is located in the Ravva offshore field in the Krishna-Godavari basin (India) and was intended to produce significant crude from a secondary reservoir section. This paper presents a case study concerning rigless remediation of microchannels in the cement packer (placed in the annulus of the production tubing and casing to isolate the producing zone) and discusses laboratory development of a customized epoxy resin system, simulations to estimate channel size, three-dimensional (3D) displacement modeling, drillout after placement, and evaluation post-placement. An epoxy resin system was selected to seal micro-annuli in a cement packer and restore zonal isolation because of its ability to develop high compressive strength, potential to resist significant strain, and its solids-free formulation. This resin system was pumped followed by an ultrafine cement slurry comprising a fine-particle high-surface-area cement blend that can penetrate small channels more easily compared to conventional cement. The top of fluids was simulated for various cases as per channel size estimations, and 3D displacement modeling was performed to incorporate fluid contamination. The strategic placement of epoxy resin and ultrafine cement focused on isolating annuli above the zone of interest. Conventional cement testing equipment was used to customize resin formulations to downhole conditions. After placement and solidification of the designed treatment, cement remaining in the tubing was successfully milled. A positive hermetical test was conducted after 48 hours of setting time, and the result was confirmed as successful. Barrier evaluation was performed using a combination of a cement bond log (CBL) tool and ultrasonic scanner. Furthermore, the acoustic impedance was post-processed to generate a derivative acoustic impedance (DZ) data set before performing the data analysis workflow. On the basis of analysis of this evaluation, the well was perforated in the pay zone interval and produced approximately 2,000 BOPD. The well was observed for several days to confirm tubing and casing isolation. The epoxy resin plus ultrafine cement blend was designed to deliver a dependable barrier. This engineering solution proved to be a highly efficient and cost-effective method for treating narrow cement channels in a deviated tubing-production casing annulus using only pressure-balanced cement placement. The epoxy resin technology has unique properties that make it best suited for remediation, particularly in tight geometries, such as in the current scenario of micro-annuli channels in a cement sheath. The resin system is solids-free (Newtonian fluid) and can provide a high-pressure seal. The system also withstands contamination (overcomes inefficient well fluid displacement), which is beneficial when prejob cleanup resources are limited. In addition, this drillable system develops compressive strength ranging from 5,000 to 15,000 psi.