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The article presents a study on the effects of photo-oxidation under accelerated ultraviolet (UV) exposure on the molecular weight and the morphology of polystyrene (PS)/organophilic montmorillonite (OMMT). The methods used in the study include the Fourier transform infrared spectroscopy, viscosimetry, and scanning electron microscopy. The materials used were supplied by BASF Co. and Southern Clay Product.

Highlights The present research investigates the influence of chemical modifications on the surface of Diss fibers (Ampelodesmos mauritanicus) as an effective reinforcing agent for biocomposites based on poly (3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV). The Diss fiber surface underwent three different chemical treatments: alkaline, alkaline/peroxide, and alkaline/silane. Changes in morphology, mechanical properties, thermomechanical behavior, and contact angle measurements of the biocomposite materials were studied according to the following weight ratio PHBV/Diss fibers 80/20. Scanning electron microscopy (SEM) analysis of the fractured surface of the biocomposite samples revealed improved adhesion between Diss fibers and the PHBV matrix after surface modification, compared with the unmodified sample. The study demonstrated that the incorporation of Diss fibers leads to an enhancement in the mechanical performances of PHBV‐based biocomposites. The tensile properties of the modified biocomposites showed a significant increase in Young's modulus compared with the biocomposites with untreated fiber. Similar trends were observed in the data obtained from dynamic mechanical analysis (DMA) and contact angle measurement. Overall, the study highlights the beneficial effects of Diss fibers modification, particularly with the alkali–silane combination, in enhancing the properties of PHBV biocomposites, there by broadening their potential application fields. The study explores the potential of Diss fibers as an effective reinforcement for PHBV‐based biocomposites. Fully biodegradable biocomposites based on PHBV/Diss fibers are melt‐compounded. Diss fibers are chemically modified by alkaline, alkaline/peroxide, and alkaline/silane. The chemical treatment has considerably enhanced the properties and morphology of the biocomposites, being however much higher for alkaline/silane treatment. The method can be used for specific applications and large‐scale production. [ABSTRACT FROM AUTHOR]

In recent years, there has been a great interest in biodegradable polymer composites. Besides polylactides, polyhydroxyalcanoates (PHA) are the most commonly used as matrices due to their biodegradability, biocompatibility and good properties compared with synthetic polymers. Despite many advantages, bio-fillers still have limited applications as reinforcement due to a lack of adhesion to polymers and their inherent high moisture absorption. Therefore, achieving a good adhesion between bio-fillers and the polymer represents one of the major challenges in composite materials. Therefore, the objective of this paper was to investigate the effect of PHBV grafted maleic anhydride (PHBV-g-MA) compatibilizer used at 5 wt. %, on the morphology and properties of PHBV/OHF biocomposites at various filler contents, i.e., 10, 20 and 30 wt.%. The study showed that PHBV-g-MA improved filler dispersion in the matrix and promoted the interactions between PHBV and OHF resulting in improved thermal stability and tensile and barrier properties compared to the non-compatibilized biocomposites. [ABSTRACT FROM AUTHOR]

Tensile and viscoelastic properties of poly(3‐hydroxybutyrate‐co‐ 3‐hydroxyhexanoate) (PHBHHx)/zinc oxide nanoparticles (ZnO‐NP) bionanocomposites prepared by melt compounding at various ZnO‐NP content ratios, i.e., 1.5, 3, and 6 wt% are investigated. The study of the comprehension of structure‐properties relationships with respect to filler content allows to define an optimized composition of PHBHHx/ZnO. The results indicate that the incorporation of ZnO‐NP led to improved tensile and viscoelastic properties overall the composition range, being however, much higher at 3 wt%. Nevertheless, the increase in both storage modulus (E′) and tensile modulus observed at 3 wt% is detrimental to flexibility and toughness compared with neat PHBHHx and the other PHBHHx/ZnO bionanocomposites. [ABSTRACT FROM AUTHOR]

The development of new bio‐based and biodegradable composites with enhanced performances is an efficient route to achieve a sustainable materials production. In this work, biocomposites materials based on PHBHHx reinforced with Agave leaves fibers (ALF) are elaborated by melt compounding at various filler content ratios, i.e., 10, 20, and 30 wt%. Thermal stability, tensile, and surface properties are investigated aiming to evaluate the effect of the ALF content on the material properties. The results show that the addition of ALF leads to reinforcement effect on PHBHHx, which is more pronounced at 30 wt%. Conversely, thermal stability of the biocomposites slightly decreases compared with the neat polymer, while the surface properties are almost unchanged whatever the filler content. [ABSTRACT FROM AUTHOR]

Films-based bionanocomposites have gained a great importance in food plastic packaging because they are eco-friendly materials and have the potential to improve food protection, while limiting the accumulation of synthetic plastics on the planet. In this paper, biofilms were prepared using poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) (PHBHHx) reinforced with Zinc oxide nanoparticles (ZnO-NPs) to develop new bionanocomposite materials intended for food packaging. The samples were fabricated using first solvent casting method followed by melt compounding at various loading rates, i.e., 1.5, 3 and 6 wt%. The obtained results showed that the incorporation of ZnO-NPs to PHBHHx at 3 wt% leads to higher crystallinity, improved mechanical properties and antimicrobial activity, compared with neat polymer and other bionanocomposites. This was attributed to the finer and homogeneous nanofiller dispersion in the polymer matrix evidenced by scanning electron microscopy analysis. Whereas at 6 wt%, the bionanocomposite sample exhibited low mechanical properties due to the formation of ZnO-NPs aggregates. In view of the obtained results, the study highlights the potential of using the PHBHHx/ZnO-NPs bionanocomposite at 3 wt% in food packaging without any prior filler treatment. [Display omitted] • ZnO-NPs were successfully incorporated in PHBHHx matrix. • The good dispersion of ZnO-NPs acted as a nucleation agent of the crystallinity. • The new prepared bionanocomposite showed excellent mechanical properties. • ZnO-NPs addition enhanced the antimicrobial activity of the bionanocomposites. [ABSTRACT FROM AUTHOR]

Blends of poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) and poly(butylene succinate) (PBS) with different PHBV/PBS weight ratios (100/0, 75/25, 50/50 and 0/100) were elaborated by melt mixing. The morphological investigation of the different samples, in comparison with that of neat PHBV and neat PBS, pointed out that PHBV/PBS blends form a biphasic system over the whole composition range. Low amount of compatibilizing agent (5 wt%), obtained by grafting maleic anhydride (MA) onto PHBV, i.e. PHBV-g-MA, was used for improving the miscibility between the two components of the blend. The incorporation of a fibrous filler as the sepiolite, easily dispersible in a polymer matrix, was also investigated. The morphology of the different blends as well as the evolution of their material properties were discussed in terms of the sepiolite and compatibilizing agent contents. The dispersion of PBS in the PHBV matrix markedly became finer with incorporation of sepiolite and PHBV-g-MA, due to enhanced interactions between the components. This paper highlighted a synergistic effect induced by the presence of both compatibilizer and sepiolite leading to an improved miscibility of the two blend components. The resulting properties were correlated with the morphology observed for the different blends. [ABSTRACT FROM AUTHOR]

Blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(butylene succinate) (PBS) at different weight ratios (80/20, 50/50 and 20/80 w/w) and ternary PHBV/PBS/halloysite nanotubes (HNT) nanocomposites were prepared by melt compounding. Typical co-continuous and nodular morphologies were obtained with the neat blends. The effect of maleic anhydride-grafted PHBV (PHBV-g-MA) compatibilizer and HNT on the nodular microstructure and thermal properties of PHBV/PBS/HNT nanocomposites was investigated. Morphological observations using scanning electron microscopy (SEM) showed an improved dispersion of PBS nodules in the immiscible PHBV/PBS 80/20 blends, owing to the diffusion and emulsifying effect of PHBV-g-MA chains at the PHBV/PBS interface. A preferential location of HNTs in the PBS nodules was observed, due to their better wettability with PBS phase. Image analysis showed that combining HNT and compatibilizer led to a reduced emulsifying effect, attributed to the formation of PHBV-g-MA/HNT aggregates that limit the diffusion of PHBV-g-MA chains at the interface. Thermogravimetric analysis (TGA) and Pyrolysis Combustion Flow Calorimetry (PCFC) showed a better thermal stability and fire reaction of PHBV in the PHBV/PBS blends as compared to neat PHBV. Incorporation of HNT in the blends decreased their thermal stability but improved significantly their fire reaction, whereas combining PHBV-g-MA and HNT seems to level the influence of each component. [ABSTRACT FROM AUTHOR]

The paper reports some experimental results on the effect of different chemical modifications of Diss fibers on the properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites involving alkaline, combined alkaline/peroxide and combined alkaline/silane treatments. The biocomposite samples loaded at 20 wt% were prepared by melt compounding. Scanning Electron Microscopy (SEM) showed a better fiber-matrix interaction between Diss fiber and matrix after surface fiber treatment. Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD) results indicated an increase in crystallinity index of the biocomposites. In addition, the incorporation of Diss fibers treated with alkali-silane resulted in an improvement in Heat Deflection Temperature (HDT) and shore D hardness from 141.1 °C and 75.1–145.7°C and 86.2, respectively, in comparison with the neat matrix. This also agreed with the flexural properties results, which showed a significant increase in flexural modulus by almost 30 % compared to the neat PHBV. The same trend was observed for water absorption. Overall, combined alkali-silane treatment was found to be most efficient surface treatment method to develop strong interfacial adhesion between PHBV and Diss fiber, increasing the scope of application in manufacturing of light weight green composites. • Effect of various surface treatments on Diss fibers used as reinforcement in PHBV-based biocomposites. • Structural and properties characterization of Diss fibers and PHBV/Diss fibers biocomposite 80/20 (w/w). • Interesting Diss source of cellulosic reinforcing materials. [ABSTRACT FROM AUTHOR]

Abstract: The oxidative degradation of neat polylactide (PLA) and PLA-Cloisite 30B (C30B) nanocomposites under gamma irradiation was studied for irradiation doses ranging from 0 to 200 kGy. The morphologies and the properties of neat PLA and PLA-C30B nanocomposites (5 wt.%) were investigated using Fourier transform infrared spectroscopy (FT-IR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (ATG), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation measurements. The results were analysed by comparing the C30B influence on the PLA degradation. Results show neat PLA is strongly degraded by gamma irradiation while PLA-C30B nanocomposites are less affected because gamma irradiation promotes the C30B layer distribution within the PLA matrix. The morphological defects were much less more pronounced for the PLA nanocomposites compared to neat PLA, for which many voids and cracks were observed after irradiation. [Copyright &y& Elsevier]

Halloysite nanotubes (HNTs) were functionalized by grafting styrene-ethylene-butylene-styrene (SEBS) copolymer chains after a two-step modification procedure. Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS) were used to determine the grafting rate. Then, raw and functionalized halloysites were incorporated into polyamide-11(PA11)/ styrene-ethylene-butylene-styrene grafted maleic anhydride (SEBS-g-MA) blends (85/15 w/w). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs show a good dispersion of both halloysites particles and SEBS-g-MA nodules in the PA11 matrix. In the case of functionalized halloysite, the presence of HNTs bundles surrounded with fine SEBS-g-MA nodules is observed. Atomic force microscopy (AFM) also highlighted the different blends morphologies. Incorporation of functionalized halloysite leads to an improvement of the thermal properties without affecting the PA11 crystallization. Moreover, mechanical performance, especially toughness, was highly improved in the presence of functionalized halloysite due to a good stress transfer from the matrix to the modified halloysite agglomerates surrounded by SEBS-g-MA. [ABSTRACT FROM AUTHOR]

Sub-micron thick flakes were obtained by sonication of vermiculite that was first exfoliated by either thermal shock or chemical treatment with hydrogen peroxide. Dimer fatty acid polyamide nanocomposites with a mixed morphology were prepared via a solution–dispersion technique. The large (in the micrometre range) vermiculite flakes assumed random orientations in the matrix. BET surface area measurements indicated flake thickness below 100 nm but SEM showed that thicker flakes were also present. Filler content was varied up to 30 wt.%. At this loading, the tensile strength doubled, the modulus increased fivefold but the elongation-at-break decreased by a factor of ten. Dynamic mechanical analysis suggests that three stiffening mechanisms were operating. The reinforcing effect of the high stiffness inorganic flakes is the primary contributor. Together with the chain confinement effect, that expresses itself in an apparent increase in the glass transition temperature, this provided an adequate rationalisation of the stiffness variation below T g . However, an additional stiffening effect is indicated at temperatures above T g . The mechanism may involve dynamic network formation based on fluctuating hydrogen bonding interactions between the matrix polymer chains and the filler particles. [ABSTRACT FROM AUTHOR]

Fast scanning chip calorimetry (FSC) has been used for analysis of the crystallization behavior of a polyamide 11/organo-modified montmorillonite (PA 11/OMMT) nanocomposite. The addition of OMMT leads to a significant increase of the crystallization temperature of the polymer matrix only on cooling faster than about 10 K s. In case of slow cooling at rates typically used in standard differential scanning calorimetry (DSC), the nucleating effect of OMMT on crystallization of PA 11 is negligible. The critical cooling rate to suppress crystallization of PA 11 and to completely vitrify the relaxed melt increases at least by one order of magnitude due to the addition of OMMT. Furthermore, the enthalpy of crystallization is nearly independent on the cooling conditions in the analyzed cooling rate range from 10 to 2 × 10 K s in PA 11/OMMT nanocomposites. Isothermal crystallization experiments confirmed that the nucleating effect of OMMT on the crystallization of PA 11 increases with supercooling, being therefore of particular importance at cooling conditions relevant in polymer processing. The evaluation of the kinetics of crystallization of the PA 11/OMMT nanocomposite by FSC and DSC in a wide range of cooling rates/supercooling has been completed by analysis of the effect of OMMT on the α/δ' polymorphism of PA 11 and the spherulitic superstructure. [ABSTRACT FROM AUTHOR]

Given the global challenge of plastic pollution, the development of new bioplastics to replace conventional polymers has become a priority. It is therefore essential to achieve a balance in the performances of biopolymers in order to improve their commercial availability. In this topic, this study aims to investigate the morphology and properties of poly(lactic acid) (PLA)/ poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) (at a ratio of 75/25 ( w / w )) blends reinforced with halloysite nanotubes (HNTs) and compatibilized with poly(lactic acid)-grafted maleic anhydride (PLA- g -MA). HNTs and PLA- g -MA were added to the polymer blend at 5 and 10 wt.%, respectively, and everything was processed via melt compounding. A scanning electron microscopy (SEM) analysis shows that HNTs are preferentially localized in PHBHHx nodules rather than in the PLA matrix due to its higher wettability. When HNTs are combined with PLA- g -MA, a finer and a more homogeneous morphology is observed, resulting in a reduction in the size of PHBHHx nodules. The presence of HNTs in the polymer blend improves the impact strength from 12.7 to 20.9 kJ/mm 2 . Further, with the addition of PLA- g -MA to PLA/PHBHHX/HNT nanocomposites, the tensile strength, elongation at break, and impact strength all improve significantly, rising from roughly 42 MPa, 14.5%, and 20.9 kJ/mm 2 to nearly 46 MPa, 18.2%, and 31.2 kJ/mm 2 , respectively. This is consistent with the data obtained via dynamic mechanical analysis (DMA). The thermal stability of the compatibilized blend reinforced with HNTs is also improved compared to the non-compatibilized one. Overall, this study highlights the effectiveness of combining HNTs and PLA- g -AM for the properties enhancement of PLA/PHBHHx blends.

The effect of hydroxyapatite (HAp) synthesized by the chemical precipitation process on the morphology and properties of composites based on poly(lactic acid) (PLA) was investigated at various filler content ratios, i.e., 5, 10 and 15 wt%. Both neat PLA and PLA-based composites were first prepared using the solvent casting method, followed by melt compounding in an internal mixer, whereas tensile specimens were obtained by thermo-compression. The study revealed that the addition of 5 wt% of HAp into the PLA led to a slight improvement in both the thermal stability and tensile properties of the composite material in comparison with neat PLA and other composite samples. Indeed, the values of the tensile strength and modulus increased from approximately 61 MPa and 2.9 GPa for the neat PLA to almost 64 MPa and 3.057 GPa for the composite sample, respectively. Moreover, the degradation temperature at a 5 wt% mass loss also increased by almost 5 °C compared to other samples, due probably to a finer dispersion of the HAp particles in the PLA, as observed under a scanning electron microscope. Furthermore, the FT-IR spectra displayed some changes in the chemical structure of the PLA/HAp (5 wt%), indicating the occurrence of filler-matrix interactions. At a higher filler content ratio, a decrease in the properties of the PLA/HAp composites was observed, being more pronounced at 15 wt%. The PLA composite containing 5 wt% HAp presents the best compromise among the investigated properties. The study highlighted the possibility of using HAp without any prior surface treatment as a reinforcement in PLA composite materials.