Vacuum Bag Research Articles

Structural design of a polymer matrix composite ship propeller

This work presents the structural design of a propeller, with its profile established using the OpenProp software for a 5 m long competition catamaran at a speed of 5.5 m/s. The materials selected using the Ashby method were polymer matrix composites, and the chosen manufacturing method was vacuum bagging. The determination of the stacking sequence was initially done using panel theory and the macromechanics of composite materials. The stacking sequence was then optimized using the finite element method with Abaqus CAE. Experimental validation was conducted through instrumented cantilever bending tests on both specimens and the blade. The finite element results showed errors of less than 5% compared to the experimental measurements, thus validating the simulations and allowing the blade to be designed with static safety factors greater than eight under operational service conditions.

Evaluation of the positional reproducibility of sedation versus non-sedation state in pediatric radiotherapy: a retrospective study

ObjectiveTo assess the positional reproducibility of sedated and non-sedated pediatric tumor patients during radiotherapy through a retrospective analysis of cone-beam computed tomography (CBCT) and planned computed tomography (CT) scan data.MethodsThe positional reproducibility of 40 pediatric tumor patients, aged 2 to 17 years with a median age of 4.5 years, who received radiotherapy under sedated and non-sedated states was retrospectively compared. The first CBCT images obtained during CT-based treatment planning were analyzed. The analysis encompassed six-dimensional positional changes, including vertical (Vrt), longitudinal (Lng), lateral (Lat), rotational (Rtn), pitch, and roll directions. Kolmogorov-Smirnov Z nonparametric rank-sum testing was employed to evaluate the positional deviations, considering absolute values regardless of directionality. Data were further stratified based on different fixation methods used during treatment.ResultsSedated patients exhibited significantly smaller positional deviations in Vrt, Lng, Lat, and Rtn directions in the body membrane group compared with their non-sedated counterparts (P<0.05). Similarly, sedated patients demonstrated reduced positional deviations in Vrt, Lng, Lat, Rtn, pitch and Roll directions in the head and neck group compared with non-sedated patients (P<0.05). Meanwhile, compared with vacuum bag plus body membrane fixation, the head and shoulder film fixation technique proved superior in terms of positional reproducibility during sedated treatment, specifically in Vrt, Lng, Lat, Pitch, and Roll directions (P<0.05). Similarly, compared with the alternative fixation method, the head and shoulder film fixation method showed better positional deviations in six-Dimensional directions in non-sedated patients (P<0.05).ConclusionWhile sedated radiotherapy may offer advantages in terms of positional reproducibility, the present study underscores the importance of considering non-sedated radiotherapy as a viable option for pediatric tumor patients. Non-sedated treatment not only provides effective tumor control but also mitigates the psychological trauma and long-term side effects associated with repeated sedative drug use. Future studies should further explore the optimal sedation and fixation strategies for pediatric radiotherapy.

Dynamic compressive impact behavior of CFRP composite under high strain rate loading

Carbon Fiber Reinforced Plastics (CFRP) composite exhibits significant sensitivity to strain rate. In this work, authors investigated the CFRP composite’s dynamic compressive impact behavior under a high strain rate. The vacuum bagging technique was used to fabricate the composite specimens to reduce the presence of voids. Compressive mechanical behavior was examined for the CFRP composite for strain rate ranging from 1384 to 1953 s−1 using a Split Hopkinson Pressure Bar (SHPB) test setup. The experiment aims to investigate the effect of strain rate on stresses, strains, failure strengths, fracture energies, and failure of quasi-isotropic CFRP composites. Furthermore, the specimens’ strength initially increases and achieves its maximum strength, followed by a decrease in strength value. Moreover, an optical microscopic examination reveals that damage in composite laminate grows as the strain rate increases.

Transverse energy absorption performance of sandwich tubes with various origami foldcores

Nowadays, composite sandwich tubes are extensively utilized in the civil and aerospace industries due to their superior strength-to-weight mechanical properties. Origami-based core offers a large enhancement of the mechanical properties, yet little study research focuses on the effect of various foldcore configurations on the transverse mechanical properties of sandwich tubes, necessitating the design method for applications. This study introduces an innovative approach by incorporating origami into the composite sandwich core to enhance the transverse energy absorption capacity. The quasi-static transverse mechanical properties of carbon fibre-reinforced polymer (CFRP) sandwich tubes with foldcores are studied under three-point bending-like local compression and transverse structural compression. A systematic geometric design framework and numerical modelling technique are provided. By integrating finite element analysis and experiments, the research investigates the effects of various origami foldcore configurations and geometric parameters on transverse energy absorption capacity. The experiment setup is provided by sandwich tubular specimens with a full-diamond configuration as the foldcore. The cylindrical tubes (foldcore) of the sandwich structures were manufactured using four plies [0°]4 of T700 (T300) woven CFRP with the hot press moulding (vacuum bag using female and male moulds) technique respectively. Then, the parametric study and damage mode analysis of eight different foldcore patterns (axial Miura, circumferential Miura, diamond, Kresling, and their curved-creased counterparts) were studied. The results showed the superior energy absorption performance of the sandwich tube with Miura-pattern foldcore over the origami-pattern counterparts, nested tube, and traditional honeycomb sandwich tube with CFRP or aluminium-made cores. Therefore, the structural parameters optimisation of the Miura pattern tube was carried out by the Response Surface method (RSM) and a design strategy for increasing the energy absorption capacity was found. The findings offer guidance for designing high-specific energy absorption tubular structures for future advanced engineering applications.

Laser-assisted automated tape laying: Effects of placement rate and heated tooling on layer bonding and tensile properties

This paper investigates the processing parameters placement rate and tooling temperature of laser-assisted automated tape laying (ATL). Plates with carbon fiber-reinforced polyether ether ketone (CF/PEEK) were produced at 6 m/min, 9 m/min and 18 m/min, and 23°C and 250°C tooling temperature, respectively. Correlations of processing conditions with micrographs, void content, thickness, the degree of crystallinity and the shear strength of the compression shear test, including a fractographic analysis, were derived. Processing conditions that increase the degree of crystallinity were only found to improve the compression shear strength at 6 m/min placement rates, primarily due to a void content below 3.4 % and degree of crystallinity above 26 %. The fractographic analysis derived from the compression shear test revealed a strong correlation between the degree of crystallinity and the size of ductile drawings. In contrast, the transverse tensile test showed no influences on the ATL processing conditions, whereas the tensile strength in fiber direction decreased by 11 % from a placement rate of 6 m/min to 18 m/min. ATL with a 250°C tooling temperature increased the strengths by 14 % compared to those at room temperature. A further tensile strength improvement of 0° and 90° to 1754 MPa and 75 MPa was obtained by a subsequent out-of-autoclave consolidation using vacuum bagging.

DESIGN AND MANUFACTURE OF BENT AND VARIABLE SECTION TUBES MADE OF FRP COMPOSITE

Manufacturing of bent composite tubes with variable cross-section is a challenge. The traditional process in composite materials uses retractable mandrels that in case of inflated or bent tubes cannot be applied. The tubular composite elements are often used in high performance bicycles, in the manufacturing of frames, handlebars, saddle pipe supports, etc. This paper presents research on the design of a Mountain Bike (MTB) riser handlebar made of Fiber Reinforced Polymer (FRP). The handlebar is numerically analyzed to estimate the most suitable stacking sequence of Carbon Fiber Reinforced Polymer (CFRP) layers. Depending on the safety standard of bicycle handlebars, a case of longitudinal bending tests was numerically evaluated. Comparing the weight of the CFRP handlebar with the steel handlebar of the same shape, the mass reduction is 5.2 times. The obtained results indicate a two-fold reduction in the weight of the handlebar if it is compared to a handlebar made of aluminum alloys. The research also presents the manufacturing process of the composite mold, and CFRP tubular element. Prepreg CFRP materials are used to manufacture the handlebar, the employed technology being the vacuum bag forming and autoclave curing process.

Assessing PET composite prosthetic solutions: A step towards inclusive healthcare

The demand for affordable prostheses is particularly high in Low Middle-Income Countries (LMICs). Currently, sockets are predominantly manufactured using monolithic thermoplastic polymers, which lack durability and strength, or consumptive thermoset resin reinforcing with expensive composite fillers like carbon, glass, or Kevlar fibers. However, there exist unmet and demanding needs among amputees for procuring low-cost, high-strength, and faster socket manufacturing methods. We evaluate a socket made from a novel manufacturing technique utilizing an affordable and sustainable composite material called commingled PET (polyethylene terephthalate) yarn, along with a reusable vacuum bag, to produce custom-made sockets in a purpose-built curing oven. Our innovative fabrication methodology enables the production of complex-shaped patient sockets in under 4 h. To evaluate the efficacy and performance of the PET sockets, we conducted trials with both unilateral and bilateral amputees over a six-month period, in collaboration with Bhagwan Mahaveer Viklang Sahayata Samiti (BMVSS) in India. Utilizing a 6-min walking test, we measured various gait parameters, including ground reaction forces and flexion angle, for both unilateral and bilateral amputees.The gait analysis conducted on amputees using our PET-based sockets demonstrated their ability to engage in daily activities without interruptions, reaffirming the functional efficacy of our approach. By combining self-reinforced PET with our novel fabrication technique, we offer a unique and accessible solution that benefits clinicians and patients alike. This study represents significant progress towards achieving affordable and personalized prostheses that cater to the needs of LMICs.

Investigation of the Effect of Hexagonal Boron Nitride Addition on the Mechanical Properties of Flax Fiber-Reinforced Composite Materials

Hexagonal boron nitride (h-BN) has recently been utilized as a reinforcement in composite materials due to its properties such as hardness, thermal conductivity, electrical insulation, and strong chemical stability. The aim of this study is to investigate the effect of nano-sized hexagonal boron nitride (h-BN) on the mechanical properties of flax fiber-reinforced composite material. For this purpose, initially, hexagonal boron nitride was added to epoxy resin in different weight ratios and homogenized without agglomeration using ultrasonic treatment. Then, by employing the hand lay-up method, the mixture was applied to flax fiber fabrics and the flax fiber-epoxy composites were produced using the vacuum bagging method. Mechanical performance of the composites, produced with 0.5%, 1%, and 1.5% by weight of hexagonal boron nitride, was determined through tensile, flexural, shear, and compression tests. Experimental results indicated that the addition of hexagonal boron nitride to flax fiber epoxy composite material increased the flexural strength and modulus compared to the unreinforced flax fiber epoxy composite material. The highest flexural strength and modulus were observed in the samples with 1.5% by weight of hexagonal boron nitride (h-BN). Consequently, it can be considered that flax fiber-epoxy composite material with hexagonal boron nitride (h-BN) addition holds potential, especially for applications subjected to bending moments.

High buttocks supine position to reduce small bowel exposure in gynecological radiotherapy

PurposeTo minimize radiation exposure to the small bowel (SB) in patients undergoing treatment for gynecological tumors by adopting a comfortable positioning method.Methods and patientsAll 76 women undergoing Intensity-Modulated Radiation Therapy (IMRT) were included in this study. Patients were immobilized in a supine position using a vacuum bag and thermoplastic cast formation. In the trial group (n = 36), patients raised their buttocks and a solid foam pad was placed under the sacral tail before immobilization. The control group (n = 40) received treatment in the standard supine position. The SB was delineated from the pubic symphysis to the total iliac bifurcation in computed tomography (CT) scans.ResultIn the trial group, a significant reduction in SB volume within the pelvic cavity was observed (mean 399.17 ± 158.7 cc) compared to the control group (mean 547.48 ± 166.9 cc), with a p-value less than 0.001. The trial group showed a statistically significant reduction in the absolute volume of irradiated SB at each dose, ranging from the low dose (10 Gy) to the high dose (45 Gy). In the control group, a negative correlation was found between SB and bladder volumes (R = -0.411, P = 0.008), whereas in the trial group, this correlation was weaker (R = -0.286, P = 0.091), with no significant relationship observed between bladder volume and SB.ConclusionThe high buttocks supine position effectively reduces SB radiation exposure without the need for bladder distension. This positioning method holds promise for reducing SB irradiation in various pelvic tumors.

Mechanical Performance on Flax Fibre Epoxy Composites Filled with Montmorillonite Nanoclay for Lightweight Applications

The objective of this study is to investigate the mechanical performance on develop flax/epoxy composite filled with montmorillonite nanoclay for lightweight applications. For this purpose, firstly, nanoclay at different weight percentages montmorillonite nanoclay such as 0.5, 1, 1.5 was dispersed homogeneously into epoxy resin with the help of ultrasanitization process. For better nanoclay distribution in composite, the montmorillonite nanoclay concentration higher than 1.5% was not analyzed. Secondly, using this mixture, flax fiber based composites were produced by vacuum bag molding process. Finally, the mechanical properties of flax/epoxy composites filled with different percentages montmorillonite nanoclay were determined with tensile, flexural, and in-plane shear test. From the experimental results obtained, the addition of montmorillonite nanoclay indicate positive effect on the performance of the composites compared with the neat composite samples, if the montmorillonite nanoclay distribute homogeneously in the epoxy. The composites added with 0.5 wt.% nanoclay showed the highest tensile modulus and tensile strength. Moreever, the elasticity modulus of composite samples with 0.5% nanoclay addition is approximately 87% higher than the pure composite. Also, the composite samples loaded with 1.5 wt.% of montmorillonite nanoclay performs better under flexural loading conditions.

Study protocol: Optimising patient positioning for the planning of accelerated partial breast radiotherapy for the integrated magnetic resonance linear accelerator: OPRAH MRL

BackgroundAccelerated partial breast irradiation (APBI) is an accepted treatment option for early breast cancer. Treatment delivered on the Magnetic Resonance integrated Linear Accelerator (MRL) provides the added assurance of improved soft tissue visibility, important in the delivery of APBI. This technique can be delivered in both the supine and prone positions, however current literature suggests that prone treatment on the MRL is infeasible due to physical limitations with bore size. This study aims to investigate the feasibility of positioning patients on a custom designed prone breast board compared with supine positioning on a personalised vacuum bag. Geometric distortion, the relative position of Organs at Risk (OAR) to the tumour bed and breathing motion (intrafraction motion) will be compared between the supine and prone positions. The study will also investigate the positional impact on dosimetry, patient experience, and position preference.MethodsUp to 30 patients will be recruited over a 12-month period for participation in this Human Research Ethics Committee approved exploratory cohort study. Patients will be scanned on the magnetic resonance imaging (MRI) Simulator in both the supine and prone positions as per current standard of care for APBI simulation. Supine and prone positioning comparisons will all be assessed on de-identified MRI image pairs, acquired using appropriate software. Patient experience will be explored through completion of a short, anonymous electronic survey. Descriptive statistics will be used for reporting of results with categorical, parametric/non-parametric tests applied (data format dependent). Survey results will be interpreted by comparison of percentage frequencies across the Likert scales. Thematic content analysis will be used to interpret qualitative data from the open-ended survey questions.DiscussionThe results of this study will be used to assess the feasibility of treating patients with APBI in the prone position on a custom designed board on the MRL. It may also be used to assist with identification of patients who would benefit from this position over supine without the need to perform both scans. Patient experience and technical considerations will be utilised to develop a tool to assist in this process.Trial registration Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN1262400067583. Registered 28th of May 2024. https://www.anzctr.org.au/ACTRN12624000679583.aspx

Successive self-nucleation and Annealing technique applied to polypropylene/butyl rubber composites: Recycling alternatives for vacuum bagging materials

The aerospace sector uses butyl rubber to manufacture carbon fiber components through an autoclave or infusion. Both manufacturing techniques require a high vacuum to achieve adequate impregnation of the carbon fiber fabrics with epoxy resin, and butyl rubber is used as the sealant. The aerospace sector discontinues materials with shelf life expired, and butyl rubber is one of the materials most discontinued for not being used within the designated time. This work presents the development of composites using polypropylene and discontinued butyl tape. Composites with 30, 50, and 70 wt% of butyl rubber content were prepared using a twin-screw extruder. The structural analysis showed that the composites with 50 wt% and 70 wt% are similar to butyl rubber, while the compound with 30 wt% of butyl is similar to polypropylene. The degree of crystallinity of the compound with 50 wt% of butyl content was 18% higher than the PP, and the melting temperature decreased by 30% with the higher butyl content. SSA revealed that the highest enthalpic contribution occurred in the crystalline fraction of higher perfection, except for the compound with 50 wt% of butyl content, whose less perfect crystalline populations grew at the expense of the most perfect crystals. The reduction of the crystalline fraction implies that butyl interferes with the formation of crystals, developing populations with lower lamellar thickness that favors the overall crystallinity of the compound. Young’s modulus, yield strength, and nominal strain decreased with butyl rubber content. The composites showed rough failure surfaces with solid butyl rubber particles and poor adhesion to polypropylene. Butyl particles with diverse sizes and geometries lead to sudden failure of the composites and high dispersion in strain values.

Low velocity impact study of vacuum bag infused bouligand inspired composites

AbstractThis work proposes three Bouligand‐inspired layups to enhance low velocity impact (LVI) damage resistance and tolerance of convectional aircraft composite laminates. Two Bouligand‐like (HL and HL_S) and one hybrid design layup, merging conventional and Bouligand architecture (HYB), were produced by vacuum bag infusion. Their performance under LVI, at 13.5, 25 and 40 (J), and compression after impact (CAI) tests were evaluated and compared with a conventional aircraft multidirectional layup (LS) produced under identical conditions. Results demonstrated that, especially for the higher impact energy levels, both Bouligand‐like laminates consistently outperformed all the other configurations, exhibiting higher load bearing capacity (peak load) and energy absorption. Additionally, the rough and poorly defined interlaminar region of Bouligand‐like layups have showed to delay severe damage for higher loads and energies, dissipating all (at 13.5 J) or most of the impact energy (more than 50%) through subcritical damage mechanisms. Compared with LS laminate, Bouligand‐inspired layups postponed the onset of severe damage thresholds by up to 120% in load and 66% in energy (HL laminate) while developing smaller and more localized damages. The high number of fibers aligned in the loading direction of LS laminate led to better damage tolerance.Highlights Vacuum bag infused Bouligand‐like laminates consistently demonstrated superior performance than the conventional aircraft multidirectional layup, exhibiting higher load bearing capacity and energy absorption, particularly at higher impact energy levels; The rough and poorly defined interlaminar region observed in both Bouligand‐like layups demonstrated to play an essential role in the efficiency of damage mechanisms, dissipating all (at low impact energy levels) or more than 50% of impact energy on subcritical damages, such as translaminar matrix cracking; Compared with the conventional layup, HL Bouligand‐like laminate postponed 120% and 66% load and energy severe damage onset thresholds; The high number of fibers aligned in the loading direction of LS laminate led to better damage tolerance, despite the larger damaged areas observed.

Ensiling sugar beets: Effect of mixer feed used for co-ensiling on fermentation products and losses when ensiled in vacuum bags

Co-ensiling beets with other feeds allows for year-round feeding of beets and reduces the risk of dry matter (DM) loss as effluent from the silage. This study aimed to evaluate the effect of co-ensiling high DM beets with maize and grass/clover silage, grass seed straw, fresh beet pulp, and high DM concentrates (dried beet pulp, wheat distillers’ grain solubles; DDGS, wheat bran, rapeseed meal, sunflower meal, soybean hulls, and maize gluten feed) on gaseous weight loss (GWL), loss of effluents, and silage quality. Beets from harvest year 2021 were used to produce two sets of silages in laboratory silos, resulting in a total of 2 pure beet silages and 12 mixed beets silages. GWL was measured by weighing the laboratory silos until 181 days of ensiling. Fermentation was terminated by freezing after 30, 92, and 181 days of ensiling where loss of effluent was also measured. Total GWL was highest in the two pure beet silages (mean ± SEM; 282 ± 5.47 and 250 ± 7.94 g/kg DM, respectively), and differed among the mixed silages depending on mixer feed. Effluent was only observed in the pure beet silage in Set 1. Silage DM content at 181 days of ensiling was lowest for the two pure beet silages (180 ± 10.9 and 165 ± 5.95 g/kg). For all silages, pH was below 4.25 by 30 days of ensiling. Ethanol concentrations at 181 days of ensiling were highest in the two pure beet silages (345 ± 11.5 and 287 ± 11.8 g/kg DM). L-lactate content of pure beet silages was 38.4 ± 1.85 and 31.1 ± 1.21 g/kg DM at 181 days of ensiling. In Set 1, L-lactate content was lower in beets ensiled with maize silage, grass seed straw, dried beet pulp, or DDGS compared to pure beet silage. In Set 2, L-lactate content was higher in beets ensiled with maize gluten feed compared to pure beet silage. Silage concentration of NH3 varied depending on mixer feed. The NH3 content at 181 days of ensiling was 0.817 ± 0.626 and 2.05 ± 0.601 g/kg DM for pure beet silages and was highest in beets ensiled with grass/clover silage in both silage sets (16.4 ± 0.63 and 17.6 ± 0.60 g/kg DM). Co-ensiling beets with forages, high DM concentrates, and protein-rich feeds included in this study lowered fermentation weight loss, eliminated the loss of effluent, and resulted in silages of good fermentation quality.

Effect of Hemp and Sheep Wool Reinforcements on Mechanical and Acoustic Properties in Natural Fibre Polymer Composite using Vacuum Bag Moulding Process

Effect of Hemp and Sheep Wool Reinforcements on Mechanical and Acoustic Properties in Natural Fibre Polymer Composite using Vacuum Bag Moulding Process

Understanding the Effect of Drilling Parameters on Hole Quality of Fiber-Reinforced Polymer Structures.

Hole quality in composite materials is gaining interest in aerospace, automotive, and marine industries, especially for structural applications. This paper aims to investigate the quality of holes performed without a backup plate, in thin plates of glass fiber-reinforced polymer (GFRP). The samples were manufactured by two different technologies: vacuum bagging and an innovative method named vacuum mold pressing. Three experiments were designed choosing the control factors that affect the maximum cutting force, delamination factor, and surface roughness of drilled holes in composite materials based on twill fabric layers. Quality analysis of the hole features was performed by microscopy investigations. The effects of the main factors on the targets are investigated using the statistical design of experiments, considering control factors, such as support opening width, weight fraction (wf), feed per tooth, and hole area. The results showed that the feed per tooth and hole area had a more significant influence on the delamination factors and surface roughness (Sa). The best quality of the holes drilled in twill-based GFRP was achieved for a lower feed rate of 0.04 mm/tooth and used a support opening width of 55 mm.

Biomimetic 3D printing: Cocoon-like silk reinforcements from discarded cocoons for hemispherical composite components

Silkworm cocoons serve as the primary raw material for silk fabric production. However, due to stringent quality requirements for silk products, only high-quality cocoons are selected, while defective ones such as spotted cocoons are relegated to low-value textile fillers or direct landfilling. To enhance the value of discarded cocoons, this study combines continuous fiber 3D printing technology with traditional molding techniques, using discarded cocoons as raw materials to create high-performance hemispherical composite materials that mimic the natural structure of silkworm cocoons, thereby achieving efficient resource reuse. Additionally, a novel random path algorithm for 3D printing was developed to address the issue of uneven fiber orientation in the manufacturing of curved composite materials. The vacuum bag molding method was utilized to combine silk-like hemispherical fiber-reinforced bodies with resin, producing hemispherical composites with a high fiber content. Extensive tensile testing on longitudinally and laterally cut cocoon fiber samples was conducted to explore the mechanical behavior in various directions, revealing unique anisotropic properties. Further tensile testing on homemade silk yarn confirmed the material's high strength and excellent toughness. Scanning Electron Microscopy (SEM) analysis demonstrated good interfacial bonding between the silk and bio-based epoxy resin within the composites. Compression tests indicated a maximum load capacity of 6717 N, showcasing exceptional impact resistance and superior energy absorption in projectile impact tests. Even under extreme loads, the hemispherical composites maintained a substantial intact area, highlighting their structural integrity advantages. This study not only breathes new life into industrial waste but also provides a new direction for the manufacturing sector to achieve a greener and more sustainable development path.

Investigation on mechanical properties and wear behavior of basalt fiber and SiO2 nanofillers reinforced composites

This study explored the fabrication and evaluation of basalt fiber-reinforced composites containing silicon dioxide (SiO2) nanofillers. Hand layup followed by vacuum bagging was used to create composite specimens with mold dimensions of 300 × 300 × 3 mm³. The mechanical properties, hardness, and wear resistance of the fabricated composites were assessed according to ASTM standards. SiO2 nanofillers significantly improved the flexural properties of the composites, with a remarkable increase of 178 % and 26 % in flexural strength and modulus, respectively. Additionally, the tensile strength and modulus of the composites were also enhanced. The hardness reached a maximum of 86 at 6 wt % SiO2, and the wear resistance improved owing to the better interfacial bonding and reduced wear debris size. Wear tests revealed that SiO2 nanofillers reduced the wear rate and weight loss, which was attributed to improved interfacial bonding and reduced wear debris size. The FESEM analysis provided insights into the fracture mechanisms, showing enhanced energy dissipation and controlled crack propagation. The study concluded that SiO2 nanofillers enhance the mechanical properties and durability of fabricated composite laminates.

Phthalate migration potential in vacuum-packed fish.

Phthalates or phthalate esters (PAEs) have become a serious concern due to their toxicity and risks of migration from contact materials to food matrices and the environment. The aim of this study is to monitor the possible migration potential of PAEs in pelagic fish stored in vacuum packaging depending on the storage time and to determine the polyethylene polymers. In order to achieve this goal, sea bass (Dicentrarchus labrax) and anchovy fish (Engraulis encrasicolus) were randomly packaged in vacuum bags and then stored for 90days. Phthalate content was determined by GC/MS technique in the muscle tissue of each fish species at certain periods (0, 30, and 90days) of storage, and on the first day in the packaging material and fish meat. As a result of the analysis performed in µ-Raman spectroscopy, no microplastics were detected in both fish species' meats. FTIR spectroscopy results of the packaging material determined nylon in the chemical content of the packaging material before processing. It has been determined that the chemical composition of the packaging used in the vacuum packaging process is affected by the temperature, depending on the storage period, and different polymer types are formed in the processed package material. It was determined that the dominant PAE homologues were Di-n-pentyl phthalate (DPENP) in both fish meat and Di-(2-ethylhexyl)-phthalate (DEHP) in the package. However, during storage, Dibutylphthalate (DBP) became dominant in anchovies and DPENP became dominant in sea bass, differing according to fish species and storage time.

Development and Manufacturing of a Fibre Reinforced Thermoplastic Composite Spar Produced by Oven Vacuum Bagging.

The limited recyclability of fibre-reinforced thermoset composites has fostered the development of alternative thermoplastic-based composites and their manufacturing processes. The most common thermoplastic-based composites are often costly due to their availability in the form of prepreg materials and to the high pressure and temperatures required for their manufacturing. Yet, the manufacturing of economic and recyclable composites, made of semi-preg composite materials using traditional composite manufacturing technologies, has only been proved at a laboratory scale through the manufacturing of flat plates. This work reports the manufacturing of a real structural part, a wing spar section with complex geometry, made of commingled polyamide 12 (PA12) fibres and carbon fibres (CFs) semi-preg and by oven vacuum bagging (OVB). The composite layup was studied using finite element analysis, and processing simulation assisted in the determination of the PA12/CF preform for OVB. Processing of two forms of semi-preg materials was first evaluated and optimised. The material selection for part manufacturing was mainly defined by the materials' processability. The spar section was manufactured in two OVB stages and was then mechanically tested. The mechanical test showed a linear strain response of the prototype up to the maximum load and validated the optimised layup configuration of the composite structure.