The impact of time on the heat resistance of self-compacting high-performance concrete incorporated with recycled martials

The influence of time on the mechanical behavior of concrete after exposure to elevated temperatures has been studied. Twenty-one self-compacting high-performance concrete mixtures with different incorporation amounts of coarse recycled concrete aggregate (RCA) and three unprocessed waste powder materials have been tested at age of 270 days for residual compressive and flexural strength after exposure to fire. The results have been compared to the results for the same concrete, which have been studied at age of 90 days. A new parameter has been introduced for comparing the responses of concrete to elevated temperatures at different ages; this parameter was the “heat resistance” which expresses the total area under the curve of the relative residual strength (compressive or flexural) after exposing to six temperature degrees (20, 150, 300, 500, 600, and 800 °C). The results showed that the age of concrete has an influence on the response of concrete to elevated temperatures. The heat resistance of compressive strength enhanced with age but the concrete behaved with a tendency different to that at the age of 90 days. The heat resistance of flexural strength has not been affected or slightly decreased but not with more than 10% to that at the age of 90 days. The used waste powder materials were unprocessed waste fly ash, waste cellular concrete powder and waste perlite powder; they proved that using any of them up to 15% as a replacement for cement with 0% or 25% of RCA enhanced the concrete resistance for the fire with time. The main two reasons for changing of residual strength with the time were the changing of water content and the proceeding of hydration of the binder. In general, long ages testing properties of concrete simulate the real behavior of concrete structures accurately.

     

Optimization of cementitious composite for heavyweight concrete preparation using conduction calorimetry

The present work investigates the hydration heat of different cement composites by means of conduction calorimetry to optimize the composition of binder in the design of heavyweight concrete as biological shielding. For this purpose, Portland cement CEM I 42.5 R was replaced by a different portion of supplementary cementitious materials (blast furnace slag, metakaolin, silica fume/limestone) at 75%, 65%, 60%, 55%, and 50% levels to obtain low hydration heat lower than 250 j g^?1. All ingredients were analyzed by energy dispersive X-ray fluorescence (EDXRF) and nuclear activation analysis (NAA) to assess the content of major elements and isotopes. A mixture of two high-density aggregates (barite and magnetite) was used to prepare three heavyweights concretes with compressive strength exceeding 45 MPa and bulk density ranging between 3400 and 3500 kg m^?3. After a short period of volume expansion (up to 4 h), a slight shrinkage (max. 0.3°/°°) has been observed. Also, thermophysical properties (thermal conductivity, volumetric specific heat, thermal diffusivity) and other properties were determined. The results showed that aggregate content and not binder is the main factor influencing the engineering properties of heavyweight concretes.

     

Influence of thermal process on microstructural and physical properties of ambient pressure dried hydrophobic silica aerogel monoliths

The experimental results of thermal process on the microstructural and physical properties of ambient pressure dried hydrophobic silica aerogel monoliths are reported and discussed. With sodium silicate as precursor, ethanol/hexamethyldisiloxane/hydrochloric acid as surface modification agent, the crack-free and high hydrophobic silica aerogel monoliths was obtained possessing the properties as low density (0.096 g/cm³), high surface area (651 m²/g), high hydrophobicity (~147°) and low thermal conductivity (0.0217 Wm/K). Silica aerogels maintained hydrophobic behavior up to 430 °C. After a thermal process changing from room temperature to 300 °C, the hydrophobicity remained unchanged (~128°), of which the porosity was 95.69% and specific density about 0.094 g/cm³. After high temperature treatment (300–500 °C), the density of final product decreased from 0.094 to 0.089 g/cm³ and porosity increased to 96.33%. With surface area of 466 m²/g, porosity of 91.21% and density about 0.113 g/cm³, silica aerogels were at a good state at 800 °C. Thermal conductivities at desired temperatures were analyzed by the transient plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.0217 to 0.0981 Wm/K as temperature increased to 800 °C, revealed an excellent heat insulation effect during thermal process.     

Performance of bio-mortar under elevated temperatures

The microbially induced calcite precipitation was used to bind sand grains, yielding consolidated material known as bio-mortar. An aerobic, urease-active and nonpathogenic Sporosarcina pasteurii microorganism was used for the induction of calcite precipitation. Three different temperatures (250, 500 and 750 °C) were applied to examine the firing resistivity of bio-mortar. The results showed that the organic fiber of died bacterial cells completely dissociates at 500 °C, causing a moderate compressive strength reduction and mass loss increment in bio-mortar. The exposure of bio-mortar to 750 °C leads to a significant compressive strength regression, due to the thermal decomposition of CaCO₃ as confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and differential thermal analysis (TG and DTA) as well as scanning electron microscopy.

     

Hydration,mechanical properties and durability of high-strength concrete under different curing conditions

The properties of high-strength concrete under standard curing condition (20 °C, 95% RH), high-temperature curing condition (50 °C) and temperature match curing condition were comparatively investigated. The cumulative hydration heat of composite binder containing fly ash and silica fume is lower than that of composite binder containing the same amount of slag. Addition of fly ash and silica fume clearly reduces the adiabatic temperature rise of concrete, but adding slag leads to higher adiabatic temperature rise than Portland cement concrete. High-temperature curing condition and temperature match curing condition lead to the sustainable increase in compressive strength of concrete containing mineral admixture, but they hinder the later-age strength development of Portland cement concrete. For cement–slag paste and cement–fly ash–silica fume paste, the non-evaporable water contents increase significantly and the pore structures are much finer under high-temperature curing condition and temperature match curing condition, which negatively affect the pore structure of Portland cement paste. The differences in properties of concrete among three curing conditions become smaller with time. The properties obtained under standard curing condition can approximately reflect the long-term properties of high-strength concrete in the real structure. The concrete prepared with cement–fly ash–silica fume composite binder has the highest compressive strength, finest pore structure and best resistance to chloride permeability under any curing condition. This composite binder is very suitable to prepare the high-strength concrete with large volume.     

Heat resistance of portland cements

Recent fire cases indicated again the importance of fire research. Fast development of construction technology requires new materials. Initiation and development of fire are strongly influenced by the choice of construction materials. In addition to their mechanical properties, their behaviour in elevated temperature is also of high importance. Residual compressive strength of concrete exposed to high temperatures is influenced by the following factors: water-to-cement ratio, cement-to-aggregate ratio, type of aggregate and water content of concrete before exposing it to high temperatures and the fire process. Therefore, mix design and composition of concrete are of high importance for high temperatures. Based on the literature, the fire resistance of concrete is influenced by the used cement type. As regards the cement type, considerable importance has been attached to the various auxiliary materials, such as slag, fly ash, trass, metakaolines and silica fume. There has been no special research devoted to the fire behaviour of pure portland cements. Pure portland cements can be made with various oxide compositions or with different grinding fineness, which increases the resistance of cements to fire. The question arises what effects grinding fineness and oxide composition have on fire resistance of cements. In my experiments, the resistance of portland cements of different composition and grinding fineness to fire (high temperature) were examined. For the test of the solidified cement paste, cement paste cubes of 30-mm edge length were prepared. The specimens were stored in water for 7 days and then in laboratory conditions for 21 days. The cubes of more than 28 days were heated to the given temperature in the furnace and then kept at the given temperature for 2 h (50, 150, 300, 500, 800 °C). Following the 2 h of thermal load, the specimens were examined once their temperature cooled down to room temperature. I have experimentally demonstrated that in case of portland cements, the grinding fineness and aluminate modulus of the cement (i.e. the oxide composition of the cement) have a significant effect on its fire resistance.     

Influence of pre-curing time on the hydration of binder and the properties of concrete under steam curing condition

There is a pre-curing period before the freshly made concrete elements were exposed to steam curing in the steam curing process. In this paper, the influence of pre-curing time on the hydration of binder and the properties of concrete under steam curing condition was investigated. Three binders were used: the pure cement, the binder containing high content of GGBS, and the binder containing high content of fly ash. Three pre-curing times (1, 3, and 6 h) and one steam curing period at 60 °C (over 8 h) were adopted. Results show that pre-curing time has limited influence on the hydration degree of binder, and compressive strength and pore structure of paste. The influence of pre-curing time has limited influence on the compressive strength and chloride permeability of the pure cement concrete and the concrete containing high content of GGBS at whether early or late ages, indicating that the proper pre-curing time can be as short as 1 h for these two concretes. Increasing pre-curing time enhances the late-age compressive strength of the concrete containing high content of fly ash significantly, but it has limited influence on the late-age permeability.     

Mechanical properties and fracture behaviors of C/C composites with PyC/TaC/PyC,PyC/SiC/TaC/PyC multi-interlayers

Carbon/carbon (C/C) composites with PyC/TaC/PyC or PyC/SiC/TaC/PyC multi-interlayers were prepared by isothermal chemical vapor infiltration, followed by Furan resin impregnation and carbonization. Microstructures, mechanical properties including flexural strength, ductile displacement, and fracture behaviors of composites were studied. Furthermore, composites were heat treated at 2000 °C to study the effects of heat treatment on mechanical properties and fracture behaviors. PyC/TaC/PyC and PyC/SiC/TaC/PyC multi-interlayers have been deposited uniformly in C/C composites. With the introduction of PyC/TaC/PyC multi-interlayers in C/C composites, the flexural strength decreases; however, the ductile displacement increases. The fracture behavior changes from brittleness (0% TaC) to pseudo-ductility (5% TaC) and high toughness (10% TaC). When PyC/SiC/TaC/PyC multi-interlayers are introduced in C/C composites, the flexural strength is improved remarkably from 270 MPa to 522 MPa, but the ductile displacement decreases obviously from 0.49 mm to 0.24 mm, and the fracture behavior becomes brittle again. After heat treatment at 2000 °C, the flexural strength decreases, but the ductile displacement increases and pseudo-ductility or high toughness can be obtained.     

Thermal degradation of α-pinene using a Py–GC/MS

Mediterranean forest fires may be accelerated, partly due to biogenic volatile organic compounds produced by vegetation, mainly monoterpenes largely represented by α-pinene. To model the propagation of biomass combustion, it is necessary to study the flammability of the produced gas mixture, and thus, necessary to identify the emitted volatile compounds. However, thermal degradation of monoterpenes is rarely experimented above 300 °C, whereas forest fires reach higher temperatures. Thus, in this work, we experimented a 2-min pyrolysis of α-pinene at temperatures from 300 to 800 °C using a Py–GC/MS device. Less than 1% of pyrolysis products were detected at 300 and 400 °C. The pyrolysis products increased then from 14 compounds at 500 °C to 31 compounds at 800 °C. Degradation of α-pinene started with its isomerization at 500 °C. At 800 °C, alkenes detected increased as well as aromatics produced through the Diels–Alder mechanism. These results are consistent with the literature on thermal degradation of α- and β-pinene presented in our article.

     

Influence of Calcination on the Properties of Nickel Oxide-Samarium Doped Ceria Carbonate (NiO-SDCC) Composite Anodes

Apart from its composition, the starting powder properties such as particle size potentially affect the triple phase boundary and the electrochemical performance. Calcination process has been identified as one of the factors that influence the particle size of the composite anode powders. This study investigates the correlation between calcination temperature and properties (i.e., chemical, physical, and thermal) of NiO–samarium-doped ceria carbonate (SDCC) composite anodes. NiO–SDCC composite anode powder was prepared with NiO and SDCC through high-energy ball milling. The resultant composite powder was subjected to calcination at various temperatures ranging from 600 °C to 800 °C. Characterizations of the composite anode were performed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy, energy dispersive spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), dilatometry, and porosity measurements. The composite anodes exhibited good chemical compatibility during XRD after calcination and sintering. The FTIR result verified the existence of carbonates in all the composite anodes. The increment in calcination temperature from 600 °C to 800 °C resulted in the growth of nanoscale particles, as evidenced by the FESEM micrographs and crystallite size. Nonetheless, the porosity obtained remained within the acceptable range for a good anodic reaction (20% to 40%). The TGA results showed gradual mass loss in the range of 400 °C to 600 °C (within the low-temperature solid oxide fuel cell region). The composite anodes calcined at 600 °C and 700 °C revealed a good thermal expansion coefficient that matches that of the SDCC electrolyte.     

Changes induced in the thermal properties of Galizian soils by the heating in laboratory conditions

The soil properties can be strongly affected by wildfires, causing direct effects on ecosystem productivity and sustainability. These effects depend, among other things, on the soil type and on the temperature reached during the fire. The variations of thermal properties of several Galizian soils heated in an oven in laboratory conditions at different temperatures (200–500 °C) during 15 min have been examined in this study. The measured properties are heat of combustion of soil organic matter, ignition temperature, specific heat and mass loss, determined using DSC 2920 TA Instruments and a TGA 7 Perkin Elmer under dry air gas flow. In agreement with other authors, this study establishes three temperature intervals with different effects on the soil: up to 200 °C, low intensity heating, with no significant changes in thermal properties; between 200 and 350 °C, medium intensity heating, with losses of organic matter up to 50%; and high intensity heating to temperature higher than 350 °C, with harmful effects on the soil organic matter. On the other hand and taking into account that the sampled soils had been affected by forest fires, the variations of thermal soil properties with the laboratory heating temperatures allowed for an estimation of the temperature reached by the soil in the real fire.     

Effects of calcination and activation temperature on dry reforming catalysts

The effect of calcination temperatures on dry reforming catalysts supported on high surface area alumina Ni/γ-Al₂O₃ (SA-6175) was studied experimentally. In this study, the prepared catalyst was tested in a micro tubular reactor using temperature ranges of 500, 600, 700 and 800 °C at atmospheric pressure, using a total flow rate of 33 ml/min consisting of 3 ml/min of N₂, 15 ml/min of CO₂ and 15 ml/min of CH₄. The calcination was carried out in the range of 500–900 °C. The catalyst is activated inside the reactor at 500–800 °C using hydrogen gas. It was observed that calcination enhances catalyst activity which increases as calcination and reaction temperatures were increased. The highest conversion was obtained at 800 °C reaction temperature by using catalyst calcined at 900 °C and activation at 700 °C. The catalyst characterization conducted supported the observed experimental results.     

Role of calcination on geopolymerization of lateritic clay by alkali treatment

In the present study, the role of calcination of a low iron lateritic clay sample was investigated to synthesize the geopolymer. The analyses like X-ray fluorescence (XRF) spectroscopy for chemical composition, X-ray diffractometry (XRD) for mineral composition, and Fourier transform infrared (FT-IR) spectroscopy & scanning electron microscopy (SEM) for structural changes upon calcination at 500, 700 and, 900 °C were used to assess the suitability of selected lateritic clay sample for geopolymer. The drop in electrical conductivity and greater consumption of calcium hydroxide by CS-900 confirmed its potential reactivity than CS-700, CS-500, and CS-Control. The quality of geopolymer derived from un-calcined and calcined lateritic clay samples by alkali activation was evaluated by comparing results of compressive strength, water absorption test, and stability in the aggressive environment of chloride, FT-IR, XRD, and SEM analyses. The experimental results reveal that the quality of geopolymer enhances as the calcination temperature of the lateritic clay sample increases, However, calcination of the lateritic clay sample at 900 °C gives significant results and yield good quality geopolymer with 24.8 MPa of compressive strength, 7.07% of water absorption and 2.22% loss in mass in an aggressive environment.     

Effect of fiber length and composition on mechanical properties of carbon fiber‐reinforced polybenzoxazine

The mechanical strength and modulus of chopped carbon fiber (CF)‐reinforced polybenzoxazine composites were investigated by changing the length of CFs. Tensile, compressive, and flexural properties were investigated. The void content was found to be higher for the short fiber composites. With increase in fiber length, tensile strength increased and optimized at around 17 mm fiber length whereas compressive strength exhibited a continuous diminution. The flexural strength too increased with fiber length and optimized at around 17 mm fiber length. The increase in strength of composites with fiber length is attributed to the enhancement in effective contact area of fibers with the matrix. The experimental results showed that there was about 350% increase in flexural strength and 470% increase in tensile strength of the composites with respect to the neat polybenzoxazine, while, compressive properties were adversely affected. The composites exhibited an optimum increase of about 800% in flexural modulus and 200% in tensile modulus. Enhancing the fiber length, leads to fiber entanglement in the composites, resulted in increased plastic deformation at higher strain. Multiple branch matrix shear, debonded fibers and voids were the failures visualized in the microscopic analyses. Defibrillation has been exhibited by all composites irrespective of fiber length. Fiber debonding and breaking were associated with short fibers whereas clustering and defibrillation were the major failure modes in long fiber composites. Increasing fiber loading improved the tensile and flexural properties until 50–60 wt% of fiber whereas the compressive property consistently decreased on fiber loading. Copyright © 2008 John Wiley & Sons, Ltd.     

The influence of titanium dioxide phase composition on dyes photocatalysis

A comparative study of TiO₂ powders prepared by sol–gel methods is presented. Titanium tetraisopropoxide was used as the precursor for the sol–gel processes. The effects of the annealing treatment on phase, crystallite size, porosity and photodegradation of dyes (methyl orange and methylene blue) were studied. The phase structure, microstructure and surface properties of the films were characterized by using X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). The X-ray diffraction was used for crystal phase identification, for the accurate estimation of the anatase–rutile ratio and for the crystallite size evaluation of each polymorph in the samples. It was found that the only TiO₂ anatase phase of the synthesized TiO₂ develops below 500 °C, between 600 and 800 °C the anatase coexist with rutile and above 800 °C only the rutile phase was found in the samples. Attention has been paid not only to crystal structures, but also to the porosity, the particle size and the photocatalytic properties. However, the annealing temperature was found to have significant influence on the photocatalytic properties. Different TiO₂ doctor blade thin films were obtained mixing the sol gel powder (100% anatase) and TiO₂ Aldrich with TiO₂ Degussa P25. The surfactant (Triton X100 or sodium dodecyl sulfate) affects the packing density of the particles during deposition and the photocatalytic degradation efficiency of the dyes. The photocatalytic degradation kinetics of methyl orange and methylene blue using TiO₂ thin film were investigated.     

Mechanical Analysis of Bio Nanocomposite Prepared from Luffa cylindrica

Luffa cylindrica (LC), a tropical vegetal product, consists of highly vascular system. It has been modified by calcium phosphate and calcium carbonate separately to produce composites of Ca-salts. The modified form of LC has been reinforced with novolac resin at 30 °C to provide cross linked polymer composites. The composites have been further sonicated at 40 °C for 1 h to produce bio nano composites. The final yield is more than 80% of the raw materials used. The physical and chemical analysis of the composites have been done. Incorporation of resin in to the inner fiber surface of LC which is rich in cellulose is confirmed from ultra-violet spectroscopy (UV), and Fourier transform infrared (FTIR) analysis. Thermal studies of the composites done in an inert atmosphere reveals that the composites decompose within a temperature range of 250 - 550 °C. The tensile parameters such as maximum stress, Young's modulus and yield strength were measured. The compressive and flexural strength of the LC fiber- reinforced composites were also studied by varying the weight of fiber in the resin.     

Properties of Calcium Phosphate Scaffolds Produced by Freeze-Casting

The pore structure of three-dimensional scaffolds applied in tissue engineering may influence the mechanical properties and cellular activity. As the optimal pore size is dependent on the specifics of the biomaterial or tissue engineering application, the ability to alter the pore size over a wide range is necessary for several scaffolds in order to meets the requirements of the applications. The aim of this study is to develop methodologies to produce calcium phosphate scaffolds with acceptable pore size and defined pore-channel interconnectivity. The pore size of calcium phosphate scaffolds is established during the freeze-drying fabrication process. In this process, material suspension is simply frozen and then dried by freeze-drier, which able to produce material with unique porous architectures, where the porosity is almost a direct replica of the frozen solvent crystals. There are two different method of freeze-casting carried out in order to study the effect of freezing temperature by which in the first method; sample being soaked with liquid nitrogen (-196 °C) for about 10 minutes before been place inside a freezer (-40 °C). In the second method, the sample was directly placed inside a freezer for casting at temperature of -40 ̊C. The results show that the pore size of the scaffolds decreased as the freezing temperature was reduced. Taken together, these results demonstrate that the methodologies applied in this study can be used to produce a range of calcium phosphate scaffolds exhibiting better compressive strength, approximately 665-875 KPa for 54-64.3% of porosity with mean pore size from 102-113 μm. The methods developed in this study provide a basis for the investigation on the effects of different freezing temperature in freeze-casting process on the porosity, morphology, and compressive properties of the calcium phosphate scaffolds.     

Multiwalled carbon nanotubes reinforced poly (ether‐ketone) nanocomposites: Assessment of rheological,mechanical, and electromagnetic shielding properties

This study investigates the effect of multiwalled carbon nanotubes (MWCNTs) content on rheological, mechanical, and EMI shielding properties in Ka band (26.5‐40 GHz) of poly (ether‐ketone) [PEK] prepared by melt compounding using twin screw extruder. Transmission electron microscopy (TEM) and field emission gun scanning electron microscopy (FEG‐SEM) studies were adopted to identify dispersion of nanotubes in PEK matrix. TEM and SEM images showed uniform dispersion of MWCNTs in PEK/MWCNT composites even at loading of 5 wt%. The rheological studies showed that the material experiences viscous (fluid) to elastic (solid) transition at 1 wt% loading beyond which nanotubes form continuous network throughout the matrix which in turn promotes reinforcement. Additionally, Van‐Gurp Palmen plot (phase angle vs complex modulus) and values of damping factor further confirm that the material undergoes viscous to elastic transition at 1 wt% loading. This reinforcement effect of nanotubes is reflected in enhanced mechanical properties (flexural strength and flexural modulus). Flexural strength and flexural modulus of PEK showed an increment of 17% upon incorporation of 5 wt% of MWCNTs. Total shielding effectiveness (SE_T) of −38 dB with very high shielding effectiveness due to absorption (SE_A ~ −34 dB) was observed at 5 wt% loading of MWCNTs in PEK matrix in the frequency range of 26.5‐40 GHz (Ka band).     

Preparation of porous nanocomposite scaffolds with honeycomb monolith structure by one phase solution freezedrying method

Biodegradable porous nanocomposite scaffolds of poly（lactide-co-glycolide）（PLGA） and L-lactic acid（LAc） oligomer surface-grafted hydroxyapatite nanoparticles（op-HA） with a honeycomb monolith structure were fabricated with the single-phase solution freeze-drying method.The effects of different freezing temperatures on the properties of the scaffolds,such as microstructures,compressive strength,cell penetration and cell proliferation were studied.The highly porous and well interconnected scaffolds with a tunable pore structure were obtained.The effect of different freezing temperature（4℃,-20℃,-80℃and -196℃） was investigated in relation to the scaffold morphology,the porosity varied from 91.2%to 83.0%and the average pore diameter varied from（167.2±62.6）μm to（11.9±4.2）μm while theσ₁₀ increased significantly.The cell proliferation were decreased and associated with the above-mentioned properties.Uniform distribution of op-HA particles and homogeneous roughness of pore wall surfaces were found in the 4℃frozen scaffold.The 4℃frozen scaffold exhibited better cell penetration and increased cell proliferation because of its larger pore size,higher porosity and interconnection.The microstructures described here provide a new approach for the design and fabrication of op-HA/PLGA based scaffold materials with potentially broad applicability for replacement of bone defects.     

Modelling physical properties of highly crystallized polyester reinforced with multiwalled carbon nanotubes

The effects of carbon nanotubes dispersion into thermoplastic polymers are complex and strongly dependent upon their aggregation state. A poly(ethylene terephthalate) (PET) matrix has been reinforced through addition of multiwalled carbon nanotubes (MWCNTs). Such an addition has generated an increase in flexural modulus and a decrease in flexural strength at room temperature, and an increase in both properties above the glass transition temperature (at 100 °C). These different behaviours, dictated by temperature, have been investigated through two different micromechanical models that have permitted to put forward hypothesis on failure mechanisms and to shed light on the role played by crystalline phase. The results of thermal analyses have shown that the heat capacity of PET nanocomposites varies according to the MWCNTs content as the flexural modulus. Such a similarity has suggested to modify the Halpin-Tsai equations (H-T), typically used to predict elastic properties of short fibres reinforced composites, in order to determine the relationships occurring between PET specific heat and aspect ratio of dispersed MWCNT. The analyses performed by means of either classical H-T (elastic modulus) or modified H-T (heat capacity) equations, provided very similar estimation of the MWCNT aspect ratios. In addition, a simple elaboration of the modified H-T equations permitted the calculation of rigid amorphous fraction (RAF) into PET. The obtained values were slightly higher than those evaluated by means of a procedure based on the loss tangent peak variation measured through dynamic mechanical experiments. The detected strength decrease at 25 °C have been attributed to crack propagation through a percolative path between crystalline coating layer of MWCNTs and PET (favoured by matrix brittleness), while at 100 °C the crack propagation is hampered by rubbery behaviour of the matrix.