Mechanical Stress Conditions Research Articles

Surfactant-assisted fabrication of room-temperature self-healable dielectric elastomer toward actuation application

Dielectric elastomers are widely used for actuation applications in emerging domains such as tunable optics, tactile displays and soft robotics. However, dielectric elastomer actuators (DEAs) are prone to suffering from electrical or mechanical damage under the conditions of high operating voltage and mechanical stress, leading to a short service time and a low reliability. To address these issues, we in this work made an attempt to facilely develop a self-healable dielectric elastomer that combines high stretchability, dielectric properties, large actuation and effective repairing of mechanical and electrical failure by constructing multitype noncovalent interactions under surfactant assistance. It is demonstrated that the as-prepared elastomer possesses good healability at room temperature. After mechanical injury, a gentle pressure can initiate the recovery of damaged region, and the elastomer film could be subjected to a huge strain of 750% after healing for 24 h. In particular, this as-fabricated DEA that suffered from accidental or repetitive breakdown could still be re-actuated stably without significantly decreasing its actuated strain after quick healing (∼5 min). It is also found that embedding a fluoroelastomer with a fluorosurfactant can achieve larger deformation (tan α = 0.57 at 30 MV/m) due to the improved electromechanical properties. Our strategy for achieving self-healing feature and high actuation performance is favorable for extending lifetime, strengthening damage tolerance and lowering excitation voltages required for the DEAs.

Evisceration of Holothuria poli by mechanical, chemical and hypoxia stress methods and its bioremediation potentials for the pisciculture wastewater

In this work, we investigated the potential benefits of Holothuria (Roweothuria) poli Delle chiaje, 1824, in the bioremediation of aquaculture farm effluents in the Mediterranean Sea as well as the impact of mechanical, chemical and hypoxic stress conditions on the process of evisceration. The usefulness of H. poli as an effective candidate for fish farm effluent bioremediation was tested by placing 14 sea cucumbers in aquaria with 50 L of aquaculture wastewater for 21 days and examining the physicochemical parameters of this wastewater at fixed times (0, 7, 14 and 21 days). Interestingly, the results clearly showed that the addition of H. poli reduces chemical oxygen demand (COD), total organic carbon (TOC) and suspended matter (SM). In the second part of this work, we examined the exposure of H. poli to mechanical, chemical and hypoxic stimuli under controlled laboratory conditions. The results showed that the evisceration was strongly induced by potassium chloride (KCl) and sodium hydroxide (NaOH), compared with magnesium chloride (MgCl2), sodium chloride (NaCl), sodium sulphate (Na2SO4) and sodium bicarbonate (NaHCO3). In addition, high mechanical pressure and hypoxia (exposure to ambient air) also resulted in the evisceration of H. poli. In conclusion, the sea cucumber H. poli is an effective candidate for the fish farm effluent bioremediation in the Mediterranean and is useful for sustainable integrative multitrophic aquaculture.

M1-linked ubiquitination facilitates NF-κB activation and survival during sterile inflammation.

Methionine 1 (M1)‐linked ubiquitination plays a key role in the regulation of inflammatory nuclear factor‐κB (NF‐κB) signalling and is important for clearance of pathogen infection in Drosophila melanogaster. M1‐linked ubiquitin (M1‐Ub) chains are assembled by the linear ubiquitin E3 ligase (LUBEL) in flies. Here, we have studied the role of LUBEL in sterile inflammation induced by different types of cellular stresses. We have found that the LUBEL catalyses formation of M1‐Ub chains in response to hypoxic, oxidative and mechanical stress conditions. LUBEL is shown to be important for flies to survive low oxygen conditions and paraquat‐induced oxidative stress. This protective action seems to be driven by stress‐induced activation of the NF‐κB transcription factor Relish via the immune deficiency (Imd) pathway. In addition to LUBEL, the intracellular mediators of Relish activation, including the transforming growth factor activating kinase 1 (Tak1), Drosophila inhibitor of apoptosis (IAP) Diap2, the IκB kinase γ (IKKγ) Kenny and the initiator caspase Death‐related ced‐3/Nedd2‐like protein (Dredd), but not the membrane receptor peptidoglycan recognition protein (PGRP)‐LC, are shown to be required for sterile inflammatory response and survival. Finally, we showed that the stress‐induced upregulation of M1‐Ub chains in response to hypoxia, oxidative and mechanical stress is also induced in mammalian cells and protects from stress‐induced cell death. Taken together, our results suggest that M1‐Ub chains are important for NF‐κB signalling in inflammation induced by stress conditions often observed in chronic inflammatory diseases and cancer.

Assessment of Preload Loss after Cyclic Loading in the OT Bridge System in an "All-on-Four" Rehabilitation Model in the Absence of One and Two Prosthesis Screws.

The aim of this study was to evaluate the stability of prosthetic screws after applying cyclic loadings in an “all-on-four” rehabilitation model with the OT Bridge system. The model was tested both with and without anterior screws. Four implant analogues following the “all-on-four” concept were inserted in an edentulous mandibular resin model. An OT Bridge system with a Cr–Co prosthetic framework was fabricated. Depending on the presence or absence of one or two anterior screws on the implant analogues, three groups were created, i.e., Gr.1: three tightening screws, Gr.2: two tightening screws, Control Group: four tightening screws. Each single group underwent subsequent 400,000 cyclic loads, simulating approximately a year of chewing by using a dynamometer machine. This cycle was repeated five times for each group, and preload loss values were evaluated on each prosthetic screw after each cycle. All the data obtained were analyzed by one-way ANOVA and Student’s t-test. No statistically significant differences after intragroup analysis were found. A statistically significant difference within the Gr.1 between the screws in positions 33 and 36, equal to 15.2% (p-value = 0.0176), was found. The OT Bridge seems a useful system to maintain the retention of a prosthesis during mechanical stress conditions even in the absence of one screw in an “all-on-four” rehabilitation. This could represent a good solution to solve the esthetic problem of the screw buccal access hole for fixed solutions.

Demethylase FTO promotes mechanical stress induced osteogenic differentiation of BMSCs with up-regulation of HIF-1α.

In orthodontics, mechanical stress plays an important role in the process of bone remodeling. Mechanical stress has an effect on osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). However, the mechanism remains to be studied. The aim of this study is to investigate the effects of demethyltransferase fat mass and obesity-associated (FTO) on osteogenic differentiation of BMSCs under mechanical stress condition. The rat BMSCs were cultured in vitro, followed by flow cytometry to identify the cell surface antigens. Osteogenic differentiation of BMSCs was induced by mechanical stress by using the flexcell tension system for 6h every day and 3days in total. BMSCs were transfected by using plasmid for FTO knockdown. The expression level of FTO, hypoxia-inducible factor (HIF)-1α, runt-related transcription factor 2(RUNX2), bone morphogenetic proteins(BMPs) and alkaline phosphatase (ALP) were measured by real-time qPCR, western blotting. ALP activity were determined by ALP staining assays. The expression of FTO and HIF-1α in BMSCs with mechanical stress were significantly higher than BMSCs without mechanical stress, also, the expression of osteogenic differentiation markers were higher in BMSCs with mechanical stress. Knockdown of FTO decreased expression of osteogenic differentiation marker and ALP activity in stretched BMSCs. In addition, the expression of HIF-1α was decreased after knocking down FTO. FTO promotes the expression of HIF-1α and osteogenic differentiation under the condition of mechanical stress. This finding may facilitate the clinical application of orthodontics and the mechanism research of mechanical stress-induced osteogenesis.

Study of Vibration Effects on Communication Filters in Substrate Integrated Technologies

The growing need of space communication systems forces the industry to innovate in order to provide more robust, economical and flexible solutions. The new substrate integrated technologies enable the development of on-board communications devices with less weight and volume than the traditional waveguide-based ones. However, it is necessary to analyse the performance of these devices in the particular working conditions of satellite communications. This work studies the integrity of the electrical response of advanced communication filters under mechanical stress conditions. Four realisations of a Ku-band microwave filter in different substrate integrated technologies were developed and tested. Two mechanical vibration tests were performed: sinusoidal sweep and random vibration. These tests emulate the transport and launching conditions of the satellite payload. Furthermore, the mechanical natural frequency of the filters and its variation after being exposed to the tests have been measured to evaluate the devices integrity. For all the filters, this frequency variation is lower than 5 %, the standard threshold. This proves that the developed filters can survive the launching conditions of satellite payload, thus qualifying the technology for spatial applications.

Characterisation of glue behaviour under thermal and mechanical stress conditions

New low-cost measuring devices require that the box housing and electronics have the cost aligned with the sensing system. Nowadays, metallic clips and/or glue are commonly used to fix the electronics to the box, thus providing the same motion of the structure to the sensing element. However, these systems may undergo daily or seasonal thermal cycles, and the combined effect of thermal and mechanical stress can determine significant uncertainties in the measurand evaluation. To study these effects, we prepared some parallel plates capacitors by using glue as a dielectric material. We used different types of fixing and sample assembly to separate the effects of glue softening on the capacitor active area and plates distance. Therefore, we assessed the sample modification by measuring the capacitance variation during controlled temperature cycles. We explored possible non-linear behaviour of the capacitance vs. temperature, and possible effects of thermal cycles on the glue geometry. Further work is still needed to properly assess the nature of this phenomenon and to study the effect of mechanical stress on the sample’s capacitance.

Three-dimensional lamellar orientation and stress condition induced sudden fracture of directional solidified γ-TiAl alloys produced by electromagnetic confinement

Ф 16.5 mm directional solidified Ti-45Al-5Nb alloys with full-lamellar microstructure were successfully obtained through electromagnetic confinement and seed crystal methods. Tensile experiments at ambient temperature were performed to evaluate the industrial processability of the alloy. Although the angle between the full-lamellar structure and the applied stress is approximately 0°, the elongation is still extremely low. The fracture morphology and internal microstructure were observed from multiple directions. Combined with external mechanical stress condition, the reason for sudden fracture was discovered and the lamella orientation control plan is proposed based on different specimen conditions. The cognition of the relationship between the lamellar orientation and mechanical performance was supplemented and expanded on the three-dimensional scale.

Influence of bending radius on the properties of flexible AMOLED displays

AbstractChoosing a suitable bending structure is an important way to optimize flexible AMOLED. In this article, we proposed and established a drop‐shape model through nonlinear finite element analysis software, comparing it with the “U”‐shaped bending model. The mechanical stress conditions under different bending radius are analyzed and compared. Aiming to find a better module folding track, we output the influence of the bending radius on the stress and strain of the device layer, so that these data and research can provide reliable support for future material selection and structural optimization. The super‐elastic and viscoelastic behaviors of optically clear adhesive are described by polynomial reduced integral and Prony series model, respectively. Both U‐shaped various layers of film and overall flexible screen module strains increase fast with the decreasing of bending radius and smaller radius will increase the fatigue damage risk. The stress and strain of the drop shape did not change significantly with the decrease of the radius. During the bending process, the most stressed part appears in the outermost TP layer. In a small radius, it can be optimized from a curved structure, and water drop and wedge shapes can be prioritized.

Topological barriers to defect nucleation generate large mechanical forces in an ordered fluid

Common fluids cannot sustain static mechanical stresses at the macroscopic scale because they lack molecular order. Conversely, crystalline solids exhibit long-range order and mechanical strength at the macroscopic scale. Combining the properties of fluids and solids, liquid crystal films respond to mechanical confinement by both flowing and generating static forces. The elastic response, however, is very weak for film thicknesses exceeding 10 nm. In this study, the mechanical strength of a fluid film was enhanced by introducing topological defects in a cholesteric liquid crystal, producing unique viscoelastic and optomechanical properties. The cholesteric was confined under strong planar anchoring conditions between two curved surfaces with sphere-sphere contact geometry similar to that of large colloidal particles, creating concentric dislocation loops. During surface retraction, the loops shrank and periodically disappeared at the surface contact point, where the cholesteric helix underwent discontinuous twist transitions, producing weak oscillatory surface forces. On the other hand, new loop nucleation was frustrated by a topological barrier during fluid compression, creating a metastable state. This generated exceptionally large forces with a range exceeding 100 nm as well as extended blueshifts of the photonic bandgap. The metastable cholesteric helix eventually collapsed under a high compressive load, triggering a stick-slip-like cascade of defect nucleation and twist reconstruction events. These findings were explained using a simple theoretical model and suggest a general approach to enhance the mechanical strength of one-dimensional periodic materials, particularly cholesteric colloid mixtures.

Xylooligosaccharides and their chemical stability under high-pressure processing combined with heat treatment

Xylooligosaccharides (XOS) are emerging prebiotic ingredients used for enriching food products due to their health-promoting properties. This study investigated XOS chemical stability after high-pressure processing (HPP) combined with heat treatment. First, orange juice was enriched with XOS (xylobiose, xylotriose, xylotetraose, xylopentaose, and xylohexaose), and then HPP-treated at 100, 300, and 600 MPa applying non-thermal (30 °C) and thermal (100 °C) conditions. Ascorbic acid (vitamin C) degradation was monitored to evaluate the extend of the severity of the treatments due to its low stability under high-energy process conditions. Also, quality attributes associated with fruit juices such as physicochemical properties (pH, soluble solid content, and ζ-potential), organic acid content (malic and citric acids), total phenolic content, antioxidant activity, and sugar content (glucose, fructose, and sucrose) were determined. The use of HPP combined with heat treatment degraded ascorbic acid up to 37% and promoted sucrose hydrolysis into glucose and fructose. However, our findings demonstrated that the XOS were chemically stable to HPP in the range of 100–600 MPa even applying thermal treatment. Therefore, XOS are promising ingredients for the formulation of functional plant-based beverages since their integrity was preserved under high mechanical and thermal stress conditions of 600 MPa and 100 °C.

Suspended cable model for layout optimisation purposes in floating offshore wind farms

The cable layout optimisation for floating offshore wind farms is a complex task due to the number of elements involved and their nature, such as dynamic cables with buoyant sections. The first step is defining a model of the suspended cables that connect wind turbines between them or to cables on the seabed (risers). A lumped mass model and the finite element method are used to find the static position and mechanical stresses of the cables, keeping a balance between computational time and the quality of the results. The model allows the inclusion of standard ancillary equipment such as bend stiffeners, buoyancy modules, clamps and tethers in order to simulate multiple configurations: double hanging, single hanging (catenary), lazy wave, steep wave and tethered wave. The external actions considered are marine growth and currents and the main cable properties are taken into account to calculate its weight, buoyancy, tensions, moments and drag forces. The information obtained after the simulation includes cable tensions, curvature, laid and suspended lengths and tether tension, when applicable. Next steps include the optimisation of the suspended cables and the full network in the farm.

Methodology to Evaluate the Mechanical Stress in High-Speed Electric Machines With Buried Magnets

High-speed electric machines are gaining importance due to their high power density. The evaluation of the mechanical stress in the rotor is a crucial part of the design process for this type of machines. It is insufficient to evaluate just the static mechanical stress at maximum speed. The dynamic mechanical stress between the state of standstill and maximum speed needs to be considered as well to ensure the high fatigue strength of the rotor. One criterion that is commonly used to analyze the dynamic load in a material is the Smith diagram. In this work, a new methodology is introduced to consider both, the dynamic and the static mechanical stress, in the rotor of a high-speed electric machine. First, the von Mises stress criterion is used to examine the static mechanical stress in the rotor core. Second, the Smith diagram is used to evaluate the dynamic mechanical stress and the high fatigue resistant of the rotor. The methodology is, then, applied to a high-speed electric machine with two different types of buried magnets: 1) a rotor with buried magnets in v-shape and 2) a rotor with a buried bar magnet. Both rotors are analyzed concerning their state of stress. It can be seen that high dynamic stress occurs at the bridges in the rotor. The stress alternates with an amplitude up to σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">alt </sub> = 290 MPa. The designs are though limited due to the high static stress at the bridges of the magnet slot.

Biobased and mechanically stiff lignosulfonate/cationic-polyelectrolyte/sugar complexes with coexisting ionic and covalent crosslinks

We prepared moldable materials from lignosulfonate, an industrial lignin derivative, using a combination of ionic crosslinking between lignosulfonate and cationic polyelectrolytes and covalent crosslinking via the Maillard reaction. The mechanical properties of the lignosulfonate/cationic-polyelectrolyte/sugar complex at the optimal composition (stress at break: 55.1 MPa; Young’s modulus: 2791.8 MPa; strain at break: 3%) were comparable to those of poly(phenylene sulfide), which is used as a high-performance engineering plastic. In addition to the good mechanical properties, the lignosulfonate/cationic-polyelectrolyte/sugar complex was water-insoluble, in contrast with the high water solubility of the complex without the reducing sugar. Furthermore, the addition of a reducing sugar (fructose) to the complexes increased adhesion to a metal substrate. These improvements in the mechanical properties, water resistance, and adhesive strength of the lignosulfonate complex will expand the applications of lignosulfonate under high mechanical stress conditions and in water and biobased adhesives. Lignosulfonate is one of the major industrial products from wood. To utilize this compound as a moldable and strong material, we prepared a complex of lignosulfonate with cationic polyelectrolytes and reducing sugars. This complex contains two different crosslinking structures, i.e., ionic crosslinking between lignosulfonate and cationic polyelectrolytes and covalent crosslinking via the Maillard reaction of amino groups with reducing sugars. The coexisting of two different crosslinking greatly improved mechanical strength, Young’s modulus, water resistance, and adhesive strength compared with solely crosslinked complexes composed of the same ingredients.

Mechanically stable solution-processed transparent conductive electrodes for optoelectronic applications

The bilayer structure of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) coating on silver nanowires (AgNWs) film is a promising structure for replacing indium tin oxide (ITO) as a flexible transparent conductive electrode. Pristine PEDOT:PSS film due to its hydrophilicity and high permeability cannot fully protect AgNWs from mechanical stress and oxidation. Here, we present a composite approach that improves mechanical properties and lifespan of the AgNWs/PEDOT:PSS electrode by adding polyvinyl alcohol (PVA) as a polymer-surfactant. It is shown that addition of PVA improves the conductivity as well as the stability of hybrid electrode under demanding mechanical stress conditions. The drop in conductivity of the hybrid electrode is only 17% after 2000 repeated bending cycles whereas the reference electrode has shown a dramatic drop of 180% in the conductivity. We speculate that generation of hydrogen bonds between PEDOT:PSS and PVA increases adhesivity and cohesivity of the conductive polymer film to the sublayer. So PEDOT:PSS-PVA film not only fixes the arrangement of AgNWs but also improves the welding on cross junction points. By addition of PVA, optoelectronic performance (Figure-of-merit (ΦTC)) of the electrode is improved from ΦTC = 2.646 × 10-3 Ω-1 for AgNWs/PEDOT:PSS to ΦTC = 3.819 × 10-3 Ω-1 for AgNWs/PEDOT:PSS-PVA electrode and power conversion efficiency (PCE) of the polymer solar cell (PSC) is increased by over 17%.

Glass Foam Made with Silicon Nitride and Manganese Oxide by Microwave Irradiation

A high mechanical strength (6.1 MPa) glass foam was produced by sintering/foaming at 830 ºC in an experimental 0.8 kW-microwave oven. The basic raw material was a colorless flat glass waste and the foaming agent was Si3N4 powder (2 wt.%). As an oxygen supplying agent, a MnO2 powder (3.1 wt.%) was used. The main physical, mechanical, thermal and morphological characteristics of the optimal sample were: apparent density of 0.47 g/cm3, porosity of 77.6%, thermal conductivity of 0.105 W/m·K, compressive strength of 6.1 MPa and pore size between 0.15-0.40 mm. The optimal glass foam sample has the required characteristics of a thermal insulation material usable under mechanical stress conditions in civil engineering. The originality of the paper is the application of the unconventional microwave heating technique, faster and more economical, unlike the other papers in the same area published in the literature, followers of the traditional conventional heating technique.

Effects of transport conditions on the stability and sensory quality of wines

The quality of wine can be affected by several factors after bottling: temperature changes, shipment time, type and amount of mechanical stress (vibrations) and environmental conditions, such as light exposure and relative humidity. The effects of delivery using different packaging systems (boxes, bottles, containers) and the impacts of mode of shipment (car, truck, airplane and cargo ship) are reviewed, along with compositional markers, the reactions leading to off-odours and/or off-flavours and the approaches to monitoring transportation conditions (temperature, relative humidity and type and entity of vibration) and their impacts on the sensory profile of the wine. Temperature fluctuations are more prevalent during the transport of wine over land than by sea, and may lead to a decrease in the fresh, fruity and floral aromas of the wine and to premature aging due to the ‘pump’ effect (repeated expansion and contraction cycles). Trans-shipment phases should be reduced to a minimum, especially in hot climates. Vibrations, even for a short period of time (15 days), can alter the overall quality of the product.

Flexible high-energy-density lithium-sulfur batteries using nanocarbon-embedded fibrous sulfur cathodes and membrane separators

To obtain soft electronics, it is essential to develop high-performance and mechanically flexible energy storage at the industry level. Herein, we report flexible high-energy-density lithium-sulfur (Li–S) batteries based on all-fibrous sulfur cathodes and separators. To implement free-standing and flexible sulfur cathodes, electrically conductive single-walled carbon nanotubes (CNTs) are impregnated with cellulose nanofibers. This fibrous structure forms a 3D porous electrode with a large surface area to improve redox kinetics and achieve a high sulfur loading content without the use of a metal collector, which can then be applied in high-energy-density batteries. These flexible sulfur cathodes are combined with a commercial glass fiber separator coated with a CNT layer through a cost-effective solution process to suppress the shuttle effects of lithium–polysulfide, thereby exhibiting robust cycling stability. The prepared Li–S batteries exhibit high capacities of 940 mAh g−1 at a charge current density of 1.57 mA cm−2 and at 25 °C, and the Coulombic efficiency exceeds 90% even after 50 charge/discharge cycles. Moreover, Li-S batteries with a high gravimetric energy density of 443 Wh kg−1 per cell is achieved, and these batteries demonstrate excellent reliability in regard to electrochemical performance even under severe mechanical stress conditions for over 100 cycles.

Hf‐ and Ti‐Based Organic/Inorganic Hybrid Dielectrics Synthesized via Chemical Vapor Phase for Advanced Gate Stack in Flexible Electronic Devices

AbstractTo achieve the low power operation required by various high performance flexible electronics, such as switching and memory devices, advanced gate dielectrics should be ultra‐thin, flexible, with low gate leakage current. Organic–inorganic hybrid dielectrics are proposed to realize this combination of attributes, where the organic matrix contributes outstanding mechanical flexibility and the inorganic component provides the required electrical characteristics. Among candidate inorganic components, HfOx and TiOx are particularly attractive because of their high dielectric constant (high‐k) and wide/narrow energy bandgap. Flexible Hf and Ti hybrid high‐k dielectrics are synthesized in this work via an initiated chemical vapor deposition (iCVD) process, where 2‐hydroxyethyl‐methacrylate (HEMA) and tert‐butyl peroxide (TBPO) are used as monomers and initiators, respectively. The synthesized Hf hybrid dielectrics exhibit a high‐k value of 9.6, leakage currents below 1.0 × 10–6 A cm–2 at 2 MV cm–1, bandgaps of 5.9 eV, and electrical breakdown fields over 3 MV cm–1. The synthesized Ti hybrid dielectrics exhibit the highest k‐value of 13.0 and decent currents below 1.0 × 10–4 A cm–2 at 2 MV cm–1 due to its narrow bandgap of 3.8 eV, making it suitable for use as a charge trapping layer for flexible memory devices, rather than as a gate dielectric. n‐type and p‐type organic thin film transistors (OTFT) prepared with the Hf hybrid dielectrics exhibit typical transfer and output characteristics, even under tensile stresses as high as 2.0% strain. Under the mechanical stress condition of 2.0% tensile strain, no noticeable degradation is observed in the Hf hybrids in terms of saturation mobility (μsat), subthreshold swing (S.S.), interface trap density (Dit), threshold voltage (VT), or hysteresis. These results show that the Hf and Ti hybrid dielectrics can enhance the performance of flexible electronics.

Poly(lactic acid)/flax composites: effect of surface modification and thermal treatment on interfacial adhesion, crystallization, microstructure, and mechanical properties

ABSTRACT In this study, unidirectional flax fabrics were used to reinforce poly(lactic acid) (PLA). Flax/PLA composites were produced by thermo-compression using as-received flax fibers and titanium dioxide (TiO2) coated flax fibers. The aim was to investigate the effect of annealing temperature and time, under quiescent or mechanical stress conditions, on the microstructure, interfacial adhesion, crystallization, and mechanical properties of composites. Results showed significant differences between oxidized-TiO2-coated flax fibers/PLA composites (oxi-TiO2-C) and as-received flax fibers/PLA composites (AR-C). Indeed, above the glass transition temperature (Tg) of PLA, the storage modulus (E’) of both composites significantly increased due to PLA crystallization. However, once E’ reached a maximum value, composites with treated flax fibers leveled off while the E’ of composites with untreated flax fibers dropped drastically. This peculiar result was explained by a partial destruction or damage of AR-C interface during PLA crystal growth. This phenomenon was not observed with oxi-TiO2-C, suggesting a good interfacial adhesion. Despite the presence of a trans-crystalline layer for both samples, it was shown that TiO2 coating of flax fibers strengthened the adhesion between flax fibers and the trans-crystalline structure. Interlaminar shear strength measurements revealed a 15% increase in the interfacial strength.