Nucleation Effect Research Articles

Enhancement of the properties of poly(L-lactide)/poly(butylene adipate-co-terephthalate) blends by introduction of stereocomplex polylactide crystallites

Herein, poly(L-lactide) (PLLA), poly(butylene adipate-co-terephthalate) (PBAT), and poly(D-lactide) (PDLA) were melt compounded by a low-temperature method to prepare ternary blends with balanced properties. Differential scanning calorimetry results and torque changes during melt blending confirmed that the stereocomplex polylactide (SC-PLA) crystallites were formed. Network structure composed of SC-PLA crystallites was formed when the PDLA content was 5 wt%, at which point the melts of the blend exhibited solid-like rheological behavior. The formation of SC-PLA crystallites increased the viscosity ratio between PLLA and PBAT melt, which led to an increase of the size of dispersed PBAT phase. Furthermore, the SC-PLA crystallites could greatly promote both nonisothermal and isothermal melt crystallization behaviors of PLLA/PBAT/PDLA ternary blends because of their effective heterogeneous nucleation effect. The ternary blend containing 2 wt% PDLA showed good toughness and had an elongation at break of 211% compared to the elongation at break of 3.5% for neat PLLA. These biodegradable blends showed excellent melt crystallization abilities as well as tailored rheological and mechanical properties, which could demonstrate their potential as traditional non-biodegradable plastic substitutes.

Dimer acid polyamide/montmorillonite bio-based film for the challenge of air cushions

The increasing use of air cushions in transport packaging brings increased environmental damage due to discarded packaging. A possible solution is to replace petroleum-based polymers with dimer acid polyamide. This work studied the qualities of dimer acid polyamide films with montmorillonite (MMT) addition. The layer structure of MMT and the heterogeneous nucleation effect augment the crystal content of the γ-crystal phase. The oxygen permeability and thermal stability of the film improve as the MMT content is increased, while optical properties decline. The mechanical properties of the film are also affected. Finite-element analysis was used to assess how long air cushions made from dimer acid polyamide/MMT film can last. The results show that dimer acid polyamide/MMT film can fully meet the requirements of air cushions for short-term transportation.

Effect of Ti microparticles on the microstructure and properties of Ni-Ti composite coating prepared by electrodeposition

In this study, Ni-Ti composite coatings were prepared using electrodeposition. Experimental results and COMSOL computer simulation revealed the effect of the Ti microparticles on the microstructure and properties of the Ni-Ti composite coating. The incorporated Ti microparticle lead to grain refinement, texture elimination which were correlated with the effect of current concentration and heterogeneous nucleation. Domains consisting of inner nano-grains and outer radial columnar grains were located around the Ti microparticles, where the Ti microparticles acted as seeds. This was closely correlated with the time-dependent plating conditions like current density and electric field lines during incorporation process of the Ti microparticles. Besides that, during the incorporation process of Ti microparticles, current density concentration on the “V”-shaped valley between closely neighboring Ti microparticles promote the presence of fine Ni grains, existing between but not belonging to the Ti microparticles. Selective deposition of Ni metal on Ti microparticle surface, local current density concentration and the aggregation of Ti microparticles were observable, contributing to the spatial heterogeneity of the microstructure. Compared with the pure Ni coating, the average hardness of the Ni-Ti composite coating increased from 2.91 ± 0.43 GPa to 3.98 ± 0.46 GPa, leading to the enhanced wear resistance. However, spatial heterogeneity of the hardness distribution was observed due to the heterogeneous microstructure of Ni-Ti composite coating, which confined the improvement of wear resistance.

The Impacts of Immersion Ice Nucleation Parameterizations on Arctic Mixed-Phase Stratiform Cloud Properties and the Arctic Radiation Budget in GEOS-5

Abstract The influence of four different immersion freezing parameterizations on Arctic clouds and the top-of-the atmosphere (TOA) and surface radiation fluxes is investigated in the fifth version of the National Aeronautics and Space Administration (NASA) Goddard Earth Observing System (GEOS-5) with sea surface temperature, sea ice fraction, and aerosol emissions held fixed. The different parameterizations were derived from a variety of sources, including classical nucleation theory and field and laboratory measurements. Despite the large spread in the ice-nucleating particle (INP) concentrations in the parameterizations, the cloud properties and radiative fluxes had a tendency to form two groups, with the lower INP concentration category producing larger water path and low-level cloud fraction during winter and early spring, whereas the opposite occurred during the summer season. The stability of the lower troposphere was found to strongly correlate with low-cloud fraction and, along with the effect of ice nucleation, ice sedimentation, and melting rates, appears to explain the spring-to-summer reversal pattern in the relative magnitude of the cloud properties between the two categories of simulations. The strong modulation effect of the liquid phase on immersion freezing led to the successful simulation of the characteristic Arctic cloud structure, with a layer rich in supercooled water near cloud top and ice and snow at lower levels. Comparison with satellite retrievals and in situ data suggest that simulations with low INP concentrations more realistically represent Arctic clouds and radiation.

Simulated migration behavior of metastable Σ3 (11 8 5) incoherent twin grain boundaries

Molecular dynamics simulations are used to examine the migration behavior of one incoherent twin, a Σ3 (11 8 5) / (8 11 5) grain boundary. The boundary is known to exhibit non-Arrhenius boundary migration that slows as temperature increases. This behavior is examined in 165 metastable structures of the same boundary and in a large simulation cell where smaller length scales can have less of an effect. The metastable boundaries show diverse migration behaviors from non-Arrhenius to Arrhenius, though the majority of them exhibit non-Arrhenius behavior. The large simulation cell sizes show no dependence on system size, eliminating concerns about the effect of facet nucleation on the migration in periodic simulation cells. However, facet structures play an important role in the migration of the metastable boundaries. Boundaries with larger facets typically migrate faster than those with smaller facets and with defects in the boundary structure.

Hydration, reinforcing mechanism, and macro performance of multi-layer graphene-modified cement composites

Multi-layer graphene (MLG) has excellent mechanical properties and a unique stacked structure. In this paper, sulphoaluminate cement replaced ordinary portland cement to prepare low-carbon ecological ultra-high-performance-concrete (UHPC); the effects of MLG on the hydration, microstructure, and mechanical properties of UHPC were investigated, revealing the hydration mechanism and reinforcing mechanism of MLG on UHPC. Results show that adding MLG can significantly enhance the macro performance of UHPC. When the MLG content is 0.08%, UHPC has better macro performance. Compared with the M0 group, the flexural strength and compressive strength of the M3 group increased by 31.6%, 35.3%, 43.3%, 50.9%, and 9.5%, 13.5%, 22.2%, 21.7% after curing for 1 d, 7 d, 28 d, and 56 d, respectively. We quantitatively characterized the content of hydration product changes in UHPC. Various characterization analyses showed that the adsorption effect and nucleation effect of MLG promoted the hydrolysis and ions exchange of Ca2+ and Al3+, which provided sites for the growth of hydration products and accelerated the hydration process of cement, forming more hydration products, including AFt (ettringite) and AH3 (gibbsite). AFt, AH3, and MLG are closely connected, filling the pores and reducing the porosity of the matrix, optimizing the pore structure, and the medium and large pores transformed into micro-nano pores. Revealing the multi-level reinforcing mechanism, namely hydration products (AFt, AH3) and MLG filling the pores; MLG prevented the extension of micro-cracks and changed micro-cracks development path through filling effect, deflection effect, pulling out, and bridging effect.

Structure and Properties of PBS/PBAT blends and nanocomposites

The use of bio-compostable polymers such as Polybutylene Succinate (PBS), Polybutylene Adipate Co-Terephthalate (PBAT) or Polylactic acid is restricted due to the barrier properties especially the water vapor transmission rate (WVTR) which is high in these commercially available polymers. The WVTR plays an important role in preserving the freshness of fruits and vegetables and it has to be optimum. Polymer blending and incorporation of nano fillers are facile routes to formation of internal structure and morphology which gives good control of barrier properties of films. Hence, crystalline structure and morphology of PBS-PBAT blends were studied in detail with respect to composition of the blend. The effect of nanofillers (Halloysite nanotubes/HNT) incorporation as well as addition of polyethylene glycol (PEG) as plasticizer on crystallization process was also investigated. The samples were cast on a glass plate substrate from solution using membrane caster at constant speed and thickness in the range of 100 microns. The composition was varied from 0 to 40 % of PBS in PBAT matrix while addition of HNT was varied from 1 to 5%. Films were air dried in an oven at 50-55 °C for 6 hr. The crystal structure development was studied using wide angle X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and the molecular interaction examined using FTIR. XRD data indicated that PBS crystals were in monoclinic α phase but the relative intensities of the 011 and 020 reflections changed drastically in the blends. The DSC analysis revealed that there was preferential growth of PBS α phase crystals with sharp melting at 110 °C. The HNT gave distinct nucleation effect with a shift in the Tc peak as well as increase of ΔHc value. The preferential nucleation by HNT could be associated with the close lattice match for the HNT and the monoclinic phase of PBS. FTIR studies indicate that the all the contents were dispersed well and show hydrogen bonding interaction at the –OH and –COOH groups. These changes in the crystallinity and crystal phase improved the barrier properties leading to the decrease in (WVTR) with the addition of PBS to PBAT as well as incorporation of HNT in the blend. WVTR decreased from 120 g/m2/day to 55 g/m2/day which is excellent for packaging of green agriculture produce.

Investigation of the Crystallization Kinetics and Melting Behaviour of Polymer Blend Nanocomposites Based on Poly(L-Lactic Acid), Nylon 11 and TMDCs WS2.

The aim of this work was to study the crystallization kinetics and melting behaviour of polymer blend nanocomposites based on poly (L-lactic acid) (PLLA), nylon 11 and tungsten disulfide nanotubes (INT-WS2), which are layered transition metal dichalcogenides (TMDCs), using non-isothermal differential scanning calorimetry (DSC). Blends containing different nylon 11 contents ranging from 20 to 80 wt.% with or without INT-WS2 were prepared by melt mixing. Evaluation of their morphology with high-resolution SEM imaging proved that the incorporation of inorganic nanotubes into the immiscible PLLA/nylon 11 mixtures led to an improvement in the dispersibility of the nylon 11 phase, a reduction in its average domain size and, consequently, an increase in its interfacial area. The crystallization temperatures of these PLLA/nylon 11-INT blends were influenced by the cooling rate and composition. In particular, the DSC results appear to demonstrate that the 1D-TMDCs WS2 within the PLLA/nylon 11-INT blend nanocomposites initiated nucleation in both polymeric components, with the effect being more pronounced for PLLA. Moreover, the nucleation activity and activation energy were calculated to support these findings. The nucleation effect of INT-WS2, which influences the melting behaviour of PLLA, is highly important, particularly when evaluating polymer crystallinity. This study opens up new perspectives for the development of advanced PLA-based nanomaterials that show great potential for ecological and biomedical applications.

Dynamical law of the phase interface motion in the presence of crystals nucleation

In this paper, we develop a theory of solid/liquid phase interface motion into an undercooled melt in the presence of nucleation and growth of crystals. A set of integrodifferential kinetic, heat and mass transfer equations is analytically solved in the two-phase and liquid layers divided by the moving phase transition interface. To do this, we have used the saddle-point method to evaluate a Laplace-type integral and the small parameter method to find the law of phase interface motion. The main result is that the phase interface Z propagates into an undercooled melt with time t as Z(t)=sigma sqrt{t}+varepsilon chi t^{7/2} with allowance for crystal nucleation. The effect of nucleation is in the second contribution, which is proportional to t^{7/2} whereas the first term sim sqrt{t} represents the well-known self-similar solution. The nucleation and crystal growth processes are responsible for the emission of latent crystallization heat, which reduces the melt undercooling and constricts the two-phase layer thickness (parameter chi <0).

Reduction of SO42− and Cl− migration rates and degradation of silica nanoparticles incorporated cement pastes exposed to co-existence of sulfate, chloride and electric fields

The reinforced concrete structures in subway engineering are generally subjected to combined exposure of chloride, sulfate and electric fields. Thus, it is necessary to reveal a way of enhancing corrosion resistance of concrete in this complicated environment condition. Although improvement of concrete properties by addition of nano silica is well known, how it can lead to the reduced transport rates of aggressive ions in the cementitious systems has not been systematically confirmed. In this work, the strengthening mechanism of nano-SiO2 on the erosion resistance of cement pastes was investigated in terms of water absorption, distribution of sulfate concentration, free chloride concentration and bound chloride concentration, ionic diffusion coefficients, crystalline phase composition, thermal gravimetric and Vickers hardness. The results indicated that the sulfate concentration exhibited a decreased trend with increasing the depth from exposed surface, while both free chloride and bound chloride concentrations first increased and then decreased gradually. The modification of silica nanoparticles on the cement pastes was remarkable, and 3% nano-silica admixed binary mixtures exhibited a significant reduction of the ionic migration rates and the accompany degradation. Moreover, replacement of 1% nano silica to cement due to pozzolanic reaction and nucleation effect dramatically led to the effective chloride capture near the exposed surface as a result of the declined porosity, which can be substantiated by X-ray diffraction and thermal gravimetric results. The results of this work are beneficial for establishment of a finer transport model in further research and provide a reference for monitoring and evaluation of durability of reinforced concrete structures serving in subway engineering.

Controlling oncogenic KRAS signaling pathways with a Palladium-responsive peptide

RAS oncoproteins are molecular switches associated with critical signaling pathways that regulate cell proliferation and differentiation. Mutations in the RAS family, mainly in the KRAS isoform, are responsible for some of the deadliest cancers, which has made this protein a major target in biomedical research. Here we demonstrate that a designed bis-histidine peptide derived from the αH helix of the cofactor SOS1 binds to KRAS with high affinity upon coordination to Pd(II). NMR spectroscopy and MD studies demonstrate that Pd(II) has a nucleating effect that facilitates the access to the bioactive α-helical conformation. The binding can be suppressed by an external metal chelator and recovered again by the addition of more Pd(II), making this system the first switchable KRAS binder, and demonstrates that folding-upon-binding mechanisms can operate in metal-nucleated peptides. In vitro experiments show that the metallopeptide can efficiently internalize into living cells and inhibit the MAPK kinase cascade.

Coupling crystal plasticity and cellular automaton models to study meta-dynamic recrystallization during hot rolling at high strain rates

Predicting microstructure and (micro-)texture evolution during thermo-mechanical processing requires the combined simulation of plastic deformation and recrystallization. Here, a simulation approach based on the coupling of a full-field dislocation density based crystal plasticity model and a cellular automaton model is presented. A regridding/remeshing procedure is used to transfer data between the deformed mesh of the large-strain crystal plasticity model and the regular grid of the cellular automaton. Moreover, a physics based nucleation criterion has been developed based on dislocation density difference and changes in orientation due to deformation. The developed framework is used to study meta-dynamic recrystallization during double-hit compression tests and multi-stand rolling in high-resolution representative volume elements. These simulations reveal a good agreement with experimental results in terms of texture evolution, mechanical behaviour and growth kinetics, while enabling insights regarding the effect of nucleation on kinetics and crystallographic texture evolution.

A comparison of shear‐mixing and solvent‐induced on phase behavior, thermal and dielectric properties of PVDF‐HFP/MOF composites

AbstractThe effects of processing techniques significantly alter on the electroactive β‐phase, thermal, and dielectric behavior of polymer composites. The metal–organic framework filler (C3N2H5)(Mg(HCOO)3), HImMg is prepared and introduced into poly(vinylidenefluoride‐co‐hexafluoropropylene) (PVDF‐HFP) matrix using two distinguished methods: melt‐mixing and solution‐casting methods. The processing conditions are important in determining the dominant phase in PVDF‐HFP. As a result of solvent‐induced crystallization, the β‐phase content of solution‐cast composites containing 10% HImMg is 22% higher than that of melt‐mixed composites. In both methods, the nucleating effect of HImMg particles increases the overall crystallinity of the polymer matrix and enhances the dielectric constant in composite films by improving the interfacial and dipolar polarization. Furthermore, the melt‐mixed composites with 7 wt% HImMg demonstrate the highest dielectric constant of 17.8 at 1 kHz, showing an enhancement of 59% compared with that of pristine PVDF‐HFP. Meanwhile, the dielectric loss is suppressed at 0.083. These findings suggest the possibility of enhancing composites' electroactive phase and dielectric properties without mechanical stretching or a large electrical field.

Polylactic acid/UV-crosslinked in-situ ethylene-propylene-diene terpolymer nanofibril composites with outstanding mechanical and foaming performance

Polylactic acid (PLA) is a promising biomass and biodegradable polymer but suffers from its brittle feature and poor foaming ability. Thus, many ductile polymers have been used to modify PLA through compounding. Although some of them can improve the toughness, the strength and rigidness of PLA are seriously scarified due to the large dosage, poor dispersion, and see-island structures. Herein, UV-crosslinking-assisted in-situ fibrillation was developed to fabricate ethylene-propylene-diene terpolymer (EPDM) nanofibril-reinforced PLA composites. Twin-screw compounding followed by melt blowing was used to stretch EPDM phase into nanofibrils, while UV-crosslinking was proposed to stabilize the EPDM nanofibrils in the final PLA/EPDM composites. Thanks to UV-crosslinking, EPDM nanofibrils with an average diameter of 94.3 nm were achieved in PLA. Due to the heterogeneous nucleating effect of UV-crosslinked EPDM nanofibrils, the crystallization rate of PLA was significantly enhanced, and refined crystal morphology with fibrous structures was obtained. Surprisingly, merely 3 wt% of UV-crosslinked EPDM nanofibrils remarkably enhanced the mechanical properties of PLA. The tensile toughness and impact strength were increased by 620% and 440%, respectively, without sacrificing strength and rigidness. Moreover, the UV-crosslinked EPDM nanofibrils also significantly improved the foaming ability of PLA. The PLA/UV-crosslinked EPDM foam with an expansion ratio of up to 28-fold was achieved for the first time by mold-opening microcellular injection molding. With the presence of UV-crosslinked EPDM nanofibrils, the expansion ratio and cell population density of the foams can be increased by 470% and 5 orders of magnitude, respectively. Owing to the super-high expansion ratio and unique micro/nanoscale structures on cell walls, the 28-fold expanded PLA/EPDM foam exhibited outstanding thermally insulating performance with a thermal conductivity of as low as 26.3 mW/m∙K.

Tailoring the tensile properties of AZ91 magnesium alloy via grain refinement

Grain refinement of AZ91 alloy was achieved via the addition of a modified Al-B inoculant to the melt, where a pronounced heterogeneous nucleation effect by AlB2 particles was observed via addition of Al-8 wt-% B master alloy up to 0.3 wt-%. Moreover, hot extrusion remarkably enhanced both strength and ductility via developing an equiaxed microstructure by dynamic recrystallisation (DRX), fragmentation/dissolution of eutectics (containing β-Mg17Al12 compound) during hot deformation, and amending casting defects. Both as-cast and extruded data followed the same Hall–Petch plot, implying that the grain size refinement is the main strengthening mechanism. Accordingly, grain refining via inoculation and thermomechanical processing was found to be a viable approach for the enhancement of strength-ductility trade-off through the improvement of tensile toughness.

A high-strength Mg-8Zn-1Mn-3Sn-1.2Gd alloy with fine MgSnGd particles by Dy modification

In the current work, we successfully prepared Mg-8Zn-1Mn-3Sn-1.2Gd-0.2Dy alloy with an excellent combination of ultimate tensile strength and ductility. The mechanism of the Dy-modified MgSnGd phase and its effect on the microstructure and mechanical properties of as-cast and as-extruded alloy were systematically investigated. Experimental results reveal that a new phase MgSn (Gd, Dy) is formed with Dy addition to Mg-8Zn-1Mn-3Sn-1.2Gd alloy, MgSn (Gd, Dy) phase can act as an effective heterogeneous nucleation site of MgSnGd phase. Meanwhile, the addition of Dy consumes Sn and Gd atoms, reducing the enrichment of solute atoms and inhibiting the MgSnGd phase's growth. The Dy addition can effectively promote the dynamic recrystallization process due to the combined effects of the refined grain structure of as-cast alloy and the particle-stimulated nucleation effect caused by dispersed MgSnGd phase. The alloy exhibits an excellent combination of high strength and ductility with the ultimate tensile strength of 384 MPa and an elongation of 14.5%. The fine-grained structure, the uniformly distributed MgSnGd particle, and MgSn (Gd, Dy) nanoparticles are mainly responsible for the ultra-high ultimate tensile strength. The high ductility is due to the fine-grained structure, appropriate decrease of dislocation density, and dynamic recrystallization.

Studies on the Performance of Granular Cement Mixed with Nanomodified Materials

Nanomodified granular cement has higher strength and durability and has a denser microstructure than traditional concrete. Nanomaterials have surface effects, filling effects, and nucleation effects, which can improve the microstructure of concrete. In order to obtain cement materials with better performance, this article will mix nano-sulfur dioxide (SiO2), nano-silica (NS), and nano-titanium oxide (NT) into granular cement to study the types and dosages of nanomaterials and the effect of curing systems on the particles. The influence of cement abrasion resistance, by adding nanomodified materials of different particle sizes to the granular cement, the cement made on the 14th and 28th days after its setting has been tested for its compression resistance, ductility deformation, and frost resistance. The experimental results show that the ductility and deformation ability of concrete mixed with nanoparticles has a more obvious effect on the ductility deformation of 30 nm NS concrete, but the effect on 30 nm NT concrete is not as significant as that of 28d nano-concrete with the optimal amount of ductility deformation. It can be seen that 15 nm NS is 6.3% higher than 30 nm NS, and 30 nm NS is 11.1% higher than 30 nm NT. This shows that, in order to play the role of the nanomodified material particle cement, it is necessary to carefully study and judge different projects in order to play a better role.

Molecular crystallization of rubrene thin films assisted by gold nanoparticles

We demonstrate that crystalline organic rubrene thin films can be obtained by a facile spin-coating method using gold (Au) nanoparticles (NPs). Dodecanethiol-functionalized Au NPs were dissolved with rubrene molecules in solvent and a thin film of Au/rubrene was prepared by a simple spin coating process. The results of confocal photoluminescence (PL) and absorption spectral mapping confirmed the local formation of orthorhombic crystalline structures of the Au/rubrene hybrid film, in contrast to the monoclinic structure of plain rubrene films. Further, the results of transmission electron microscopy (TEM) and X-ray diffraction analysis, as well as Raman spectroscopy measurements of the rubrene and Au/rubrene films suggested the formation of high crystalline Au/rubrene film. The molecular crystallization of the Au/rubrene hybrid film is attributed to the nucleation effect of the Au NPs.

Influence of hydrogen and helium nucleation on the mechanical properties of beryllium by first-principles calculations

A systematic investigation has been conducted to clearly elucidate the physical pictures of H, He, and hybrid bubbles nucleation and their effects on the mechanical properties of beryllium for the application in extreme environment. The simulation is carried out by first-principles calculations based on the density functional theory as implemented in VASP. The change of the configurational entropy has been considered throughout the simulation. In the nucleation of H bubble H m -2V B e along the direction of 〈 0001 〉 , the structures of a triangle and a tetragon in the plane of ( 11 2 ̄ 0 ), a hexahedron and two symmetrically distributed hexahedron have been successively observed as more H atoms are captured. The deformation degree increases with the increase of number of H atoms. For the nucleation of He bubble He n -2V B e along the direction of 〈 1 ̄ 102 〉 , the structures of an isosceles triangle in the plane of ( 11 2 ̄ 0 ), an octahedron and a regular polyhedron have also been observed as more and more He atoms are captured. The total nucleation free energy change always remains negative when fifteen He atoms are captured due to the production of new vacancies induced by self-trapping mechanism. The degree of distortion is more serious compared with that induced by H atoms. For the nucleation of hybrid bubble, the separate nucleation of H and He bubbles begin to interact with each other by exchanging atoms with the trapping of eight He atoms. The influence of retained H and He atoms on the mechanical properties of bulk Be has been characterized by first-principles uniaxial tensile test and the essence of weakening effect has been elucidated by charge density. The Young’s modulus of pure Be is consistent with experimental result. Both the nucleation of H, He, and hybrid bubbles could cause the reduction of the Young’s modulus and the tensile strength of Be. The degradation induced by He bubble is more severe than that of H bubble. • Some interesting structures are observed during the nucleation of H/He bubbles. • The configurational entropy is considered to estimate the nucleation of bubbles. • New vacancies are induced by the self-trapping mechanism. • The effect of bubbles nucleation on the mechanical properties of Be is elucidated.

Effect of Graphene Nanofibers on the Morphological, Structural, Thermal, Phase Transitions and Mechanical Characteristics in Metallocene iPP Based Nanocomposites

Several nanocomposites were prepared by extrusion from a commercial metallocene-type isotactic polypropylene (iPP) and different amounts of two types of graphene (G) nanofibers: ones with a high specific surface, named GHS, and the others with a low specific surface, labeled as GLS. The number of graphene layers was found to be around eight for GLS and about five in the GHS. Scanning electron microscopy (SEM) images of the resultant iPP nanocomposites showed a better homogeneity in the dispersion of the GLS nanofibers within the polymeric matrix compared with the distribution observed for the GHS ones. Crystallinity in the nanocomposites turned out to be dependent upon graphene content and upon thermal treatment applied during film preparation, the effect of the nature of the nanofiber being negligible. Graphene exerted a noticeable nucleating effect in the iPP crystallization. Furthermore, thermal stability was enlarged, shifting to higher temperatures, with increasing nanofiber amount. The mechanical response changed significantly with nanofiber type, along with its content, together with the thermal treatment applied to the nanocomposites. Features of nanofiber surface played a key role in the ultimate properties related to superficial and bulk stiffness.