Explore the vast range of titles available.

When the thermoplastic composites reach the service limits during the service, the recovery and utilization are the key concerns. Meanwhile, the improvement of strength, toughness and durability of epoxy resin is the effective method to prolong the service life of materials and structures. In the present paper, three kinds of thermoplastic resins (polypropylene-PP, polyamide 6-PA6 and polyether-ether-ketone-PEEK) and composites (carbon fiber-PEEK, glass fiber-PA6 and glass fiber-PP) were adopted as the fillers to reinforce and toughen the epoxy resin (Ts). The mechanical, thermal and microscopic analysis were conducted to reveal the performance improvement mechanism of Ts. It can be found that adding thermoplastic resin and composite fillers at the low mass ratio of 0.5~1.0% brought about the maximum improvement of tensile strength (7~15%), flexural strength (7~15%) and shear strength (20~30%) of Ts resin. The improvement mechanism was because the addition of thermoplastic fillers can prolong the cracking path and delay the failure process through the load bearing of fiber, energy absorption of thermoplastic resin and superior interface bonding. In addition, the thermoplastic composite had better enhancement effect on the mechanical/thermal properties of Ts resin compared to thermoplastic resin. When the mass ratio was increased to 2.0~3.0%, the agglomeration and stress concentration of thermoplastic filler in Ts resin appeared, leading to the decrease of mechanical and thermal properties. The optimal addition ratios of thermoplastic resin were 0.5~1.0% (PEEK), 1.0~2.0% (PA6) and 0.5~1.0% (PP) to obtain the desirable property improvement. In contrast, the optimal mass ratios of three kinds of composite were determined to be 0.5~1.0%. Application prospect analysis indicated adding the thermoplastic resin and composite fillers to Ts resin can promote the recycling and reutilization of thermoplastic composites and improve the performance of Ts resin, which can be used as the resin matrix, interface adhesive and anti-corrosion coating.

When thermoplastic resins such as polyethylene (PE) and polypropylene (PP) are selected as wood adhesives to bond wood particles (fibers, chips, veneers) by using the hot-pressing technique, the formaldehyde emission issue that has long existed in the wood-based panel industry can be effectively solved. In this study, in general, thermoplastic-bonded wood-based panels presented relatively higher mechanical properties and better water resistance and machinability than the conventional urea–formaldehyde resin-bonded wood-based panels. However, the bonding structure of the wood and thermoplastic materials was unstable at high temperatures. Compared with the wood–plastic composites manufactured by the extruding or injection molding methods, thermoplastic-bonded wood-based panels have the advantages of larger size, a wider raw material range and higher production efficiency. The processing technology, bonding mechanism and the performance of thermoplastic-bonded wood-based panels are comprehensively summarized and reviewed in this paper. Meanwhile, the existing problems of this new kind of panel and their future development trends are also highlighted, which can provide the wood industry with foundations and guidelines for using thermoplastics as environmentally friendly adhesives and effectively solving indoor pollution problems.

Reactive thermoplastics are advantageous for wind turbine blades because they are recyclable at end of life, have reduced manufacturing costs, and enable thermal joining and shaping. However, there are challenges with manufacturing wind components from these new materials. This work outlines the development of manufacturing processes for a thick glass fiber–reinforced acrylic thermoplastic resin wind turbine blade spar cap, with consideration given to effects of the exothermic curing reaction on thick composite parts. Comparative elastic properties of these infusible thermoplastic materials with epoxy thermoset materials, as well as thermoplastic coupon components, are also included. Based on the results of this study it is concluded that the thermoplastic resin system is a viable candidate for the manufacturing of wind turbine blades using vacuum-assisted resin transfer molding. Significant gains in energy savings are realized avoiding heated molds, ability for recycling, and providing an opportunity for utilizing thermal welding.

The interfacial modification of basalt-fiber-reinforced polymer (BFRP) composites is an essential research field and many techniques have been developed to improve the adhesion between basalt fiber (BF) and the matrix. However, most studies were based on the matrixes of general plastics and epoxy resins. In this work, five different chain structures of thermoplastic sizing agents were used to improve the interfacial properties of unidirectional BF-reinforced soluble and high-temperature-resistant poly(phthalazinone ether nitrile ketone) (BF/PPENK) composites. DMA results showed that the poly(ether nitrile) (PEN)-sized BF/PPENK (BF-PEN/PPENK) composite exhibited the optimal interfacial performance, with a storage modulus (E′) and glass transition temperature (Tg) up to 50 GPa and 288 °C, respectively. Moreover, the tensile strength, compressive strength, flexural strength, and interlaminar shear strength of the BF-PEN/PPENK composite reached 778 MPa, 600 MPa, 1115 MPa and 57 MPa, respectively, and increased by 42%, 49%, 20% and 30% compared with the desized BF/PPENK composite. This study provides some suggestions for the design of sizing agents to modify the interface of BF and high-performance thermoplastic resin.

This paper presents an extensive comparison of the mechanical properties and failure mechanisms of a recently developed thermoplastic (Elium ®) 3D fabric-reinforced composite (3D-FRC) with the conventional thermoset (epoxy) 3D-FRC. Experiments involved tensile tests, compression tests, V-notch shear tests, and short beam shear tests for specimens produced through the vacuum-assisted resin infusion process in each case. These tests were used for the determination of in-plane elastic constants, failure strengths and for investigating the failure mechanisms. A micro-mechanical model validated against these experiments was used to predict the remaining orthotropic elastic constants. This work enhances our understanding of the mechanics of infusible thermoplastic 3D-FRC as a new class of emerging materials and provides useful data which substantiates that this unconventional thermoplastic resin is also easier to recycle, uses similar manufacturing processes and can be a suitable replacement for conventional thermoset resins.

Abstract Thick-section composites (10–100 mm) are increasingly used in structurally demanding applications. Growing interest in sustainable alternatives has driven the development of recyclable, room-temperature-processable liquid thermoplastic resins to replace thermosets in vacuum-infused composites. However, managing the thermal effects of polymerisation to avoid boiling and defects remains a challenge in thick-laminate manufacturing . While low-exotherm grades are available, their behaviour in thick laminates remains poorly understood. This study examines the exothermic polymerisation of Elium® 188 XO, a low-exotherm thermoplastic resin, in laminates with thicknesses of 9.5 mm, 17.9 mm and 26.4 mm. Process times are presented to support implementation. Using five embedded thermocouples, maximum temperatures of 86.5°C, 92.6°C and 93.9°C were recorded, all remaining below the resin’s boiling point. The results indicate a progressive increase in interlaminar temperature with increasing laminate thickness. Ambient-temperature-adjusted data showed peak increases of 2.7°C and 3.1°C between successive laminate thicknesses. These findings provide critical insights into polymerisation behaviour, informing process optimisation and industrial adoption.

Natural plant fibers (NPFs) have emerged as a sustainable alternative in the manufacture of composites due to their renewability and low environmental impact. This has led to a significant increase in the use of natural plant fiber-reinforced polymers (NPFRPs) in a variety of industries. The diversity of NPF types brings a wide range of properties and functionalities to NPFRPs, which in turn highlights the urgent need to improve the properties of fiber materials in order to enhance their performance and suitability. This paper provides insight into the processing mechanisms behind NPF fiber treatments, exploring how these treatments affect the mechanical, thermal and environmental properties of NPFRPs. It also offers a critical assessment of the advantages and disadvantages of physical, chemical, biological and nanotechnological treatments. The findings of our analysis provide a basis for the development of future treatments that aim to enhance the material properties of NPFRPs, thereby increasing their competitiveness with conventional synthetic fiber-reinforced polymers. Finally, a novel thermoplastic resin composite system, Elium–NPFRP, is proposed that embodies the principles of green development. The system has been designed with the objective of capitalizing on the environmental benefits of NPFs while simultaneously addressing the challenges associated with the integration of NPFs into polymer matrices. The Elium–NPFRP composite system not only exemplifies the potential of NPFs for sustainable materials science, but is also a practical solution that can be implemented in a diverse range of applications, spanning automotive components to construction materials. This has the potential to reduce carbon footprints and promote a circular economy.

To further improve the mechanical properties of thermoplastic resin in additive manufacturing (AM), this paper presents a novel method to directly and quantitatively place the short fibers (SFs) between two printing process of resin layers. The printed composite parts with SFs between the layers was reinforced. The effects of single-layer fiber content, multi-layer fiber content and the length of fibers on the mechanical properties of printed specimens were studied. The distribution of fibers and quality of interlayer bonding were assessed using mechanical property testing and microstructure examination. The results showed that the tensile strength of the single-layered specimen with 0.5 wt% interlayered SFs increased by 18.82%. However, when the content of SFs continued to increase, the mechanical properties declined because of the increasing interlayered gap and the poor bonding quality. In addition, when the interlayered SFs length was 0.5–1 mm, the best reinforcement was obtained. To improve the interfacial bonding quality between the fiber and the resin, post-treatment and laser-assisted preheating printing was used. This method is effective for the enhancement of the interfacial bonding to obtain better mechanical properties. The research proves that adding SFs by placement can reduce the wear and breakage of the fibers compared to the conventional forming process. Therefore, the precise control of the length and content of SFs was realized in the specimen. In summary, SFs placement combined with post-treatment and laser-assisted preheating is a new method in AM to improve the performance of thermoplastic resin.

This study investigates the flexural behavior of three sandwich panels composed of an agglomerated cork core and skins made up of cross-ply [0,90]2 flax or glass layers with areal densities of 100 and 300 g/m2. They are designated by SF100, SF300, and SG300, where S, F, and G stand for sandwich material, flax fiber, and glass fiber, respectively. The three sandwich materials were fabricated in a single step using vacuum infusion with the liquid thermoplastic resin Elium®. Specimens of these sandwich materials were subjected to three-point bending tests at five span lengths (80, 100, 150, 200, and 250 mm). Each specimen was equipped with two piezoelectric sensors to record acoustic activity during the bending, facilitating the identification of the main damage mechanisms leading to flexural failure. The acoustic signals were analyzed to first track the initiation and propagation of damage and, second, to correlate these signals with the mechanical behavior of the sandwich materials. The obtained results indicate that SF300 exhibits 60% and 49% higher flexural and shear stiffness, respectively, than SG300. Moreover, a comparison of the specific mechanical properties reveals that SF300 offers the best compromise in terms of the flexural properties. Moreover, the acoustic emission (AE) analysis allowed the identification of the main damage mechanisms, including matrix cracking, fiber failure, fiber/matrix, and core/skin debonding, as well as their chronology during the flexural tests. Three-dimensional micro-tomography reconstructions and scanning electron microscope (SEM) observations were performed to confirm the identified damage mechanisms. Finally, a correlation between these observations and the AE signals is proposed to classify the damage mechanisms according to their corresponding amplitude ranges.

Thermoplastic resin transfer molding (T-RTM) technology was applied to synthesize graphene nanoplatelets-based nanocomposites via anionic ring-opening polymerization (AROP). Polyamide 6 (PA6) was obtained by AROP and was used as the polymeric matrix of the developed nanocomposites. The non-isothermal crystallization behavior of PA6 and nanocomposites was analyzed by differential scanning calorimetry (DSC). Nanocomposites with 0.5 wt.% of graphene nanoplatelets (GNPs) with two different diameter sizes were prepared. Results have shown that the crystallization temperature shifted to higher values in the presence of GNPs. This behavior is more noticeable for the nanocomposite prepared with smaller GNPs (PA6/GN). The crystallization kinetic behavior of all samples was assessed by Avrami and Liu’s models. It was observed that GNPs increased the crystallization rate, thus revealing a nucleating ability, and also validated the reduction of half-time crystallization values. Such tendency was also supported by the lower activation energy values determined by Friedman’s method.