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This study investigates the morphology and properties of biocomposites based on a blend of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and poly (lactic acid) (PLA) 50/50 (w/w) reinforced with untreated (UNDF) and alkali‐treated (ATDF) Diss (Ampelodesmos mauritanicus) fibers at 20 wt. %. Moreover, PHBV‐g‐MA used as the compatibilizer was added at 5 wt. % to the alkali‐treated biocomposites. Morphology, and crystallinity, thermal, thermo‐mechanical, rheological and mechanical properties of PHBV/PLA biocomposites were studied. The study showed that the treated Diss fibers were uniformly dispersed in both PLA and PHBV phases. This results in a good interfacial adhesion between the components, as observed by scanning electron microscopy (SEM). Further, the results also indicated that the compatibilized biocomposite samples showed an enhancement in crystallinity degree and heat deflection temperature (HDT) passing from 48.7% to 62.4% and 119.2 to 132.9°C, respectively, in comparison with the neat blend. Similar trend is also observed with the tensile data indicating a significant increase in Young's modulus by almost 48.5% compared to PHBV/PLA matrix. This is due to better interactions between Diss fibers and PHBV/PLA matrix. The results suggest the occurrence of a synergistic effect between PHBV‐g‐MA and alkali‐treated Diss fibers in the development of materials with interesting properties and could be a potential means to expand their applications. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the optimal formulation of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx)/ZnO bionanocomposites for food packaging applications with respect to filler content ratio. Bionanocomposite samples prepared by melt-compounding at various ZnO-NPs contents (1.5, 3, and 6 wt%) were evaluated in terms of optical, thermal, viscoelastic, and mechanical properties. UV–Vis spectroscopy revealed a significant enhancement in the photochemical stability of PHBHHx/ZnO bionanocomposites compared with neat PHBHHx, which exhibits a strong absorption band at wavelengths below 380 nm, thus confirming the anti-UV activity of ZnO nanoparticles. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) demonstrated improved thermal stability and increased stiffness/mechanical strength with increasing ZnO-NPs content. Notably, the bionanocomposite with 3 wt% of ZnO exhibited the most substantial improvements, with a 20% increase in thermal decomposition temperature and a 30% increase in storage's modulus at room temperature than the neat PHBHHx. Moreover, a decrease in loss modulus (E″) and tanδ indicated reduced energy dissipation and enhanced material elasticity. Overall, incorporating 3 wt% ZnO nanoparticles into PHBHHx resulted in a bionanocomposite with superior photochemical stability, thermal stability, and viscoelastic properties compared to both neat PHBHHx and other bionanocomposite samples, which makes it as a promising candidate for food packaging applications. [ABSTRACT FROM AUTHOR]

The objective of the paper is to investigate the effect of organo‐modified sepiolite (MSep) on morphology, mechanical, and viscoelastic properties of polyamide‐11 (PA11) prepared by melt compounding at 5 wt.%. The study reveals that the addition of both unmodified sepiolite (USep) and organo‐MSep to PA11 improves the reinforcement effect of the nanocomposite materials compared to neat PA11, being however more pronounced for the organo‐modified one. Indeed, morphological analysis by transmission electron microscopy (TEM) shows a finer dispersion of organo‐MSep in PA11 matrix than the unmodified one, which is characterized by a significant presence of fibers aggregates in number and size. Further, dynamic mechanical analysis (DMA) results are in a good agreement with both tensile properties and TEM observations. [ABSTRACT FROM AUTHOR]

This work aims at investigating the effect of two eco‐friendly chemical treatments of Agave Americana fibers (AAFs) on morphology and mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx) biocomposites prepared by melt compounding. Acid citric and sodium bicarbonate treatments are used separately to modify the fiber surface before their incorporation into PHBHHx matrix at 30 wt%. The study reveals through SEM observations that the fracture surface of untreated PHBHHx biocomposite shows a poor fiber‐matrix adhesion with the presence of many microvoids at interface and also some fibers pullout. However, less surface defects with a finer morphology are observed on the treated biocomposite samples resulting in improved tensile and flexural properties compared with neat polymer, being however, more pronounced for those modified with sodium bicarbonate. The study highlights the beneficial effect of the green treatments investigated to enhance the mechanical properties of PHBHHx biocomposites. [ABSTRACT FROM AUTHOR]

Chemical treatments are used to remove hydrophilic OH groups and surface particles from the fiber surface for increasing aspect ratio of fibers and subsequently, mechanical properties. In this paper, the effect of two eco‐friendly chemical treatments on morphology, chemical structure, and thermal stability of Agave Americana fibers (AAFs) is investigated. The first chemical treatment of AAF is based on citric acid (C6H8O7) to substitute OH groups contained in AAF by ester groups, while the second one involves sodium bicarbonate (NaHCO3) to remove the lignin and hemicellulose components with the aim to promote good fiber‐matrix adhesion. Attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR) data shows that both treatments are efficient to remove hemicelluloses and a part of lignin contained in AAF resulting in a rough and clean fiber surface. Thermal stability of AAF has clearly increased by NaHCO3 treatment compared to untreated one, unlike C6H8O7, which reduces this property. The study highlights the possibility of substituting conventional polluting chemical treatments with environmentally friendly ones to modify the surface of plant fibers for polymer composites reinforcement. [ABSTRACT FROM AUTHOR]

Polymer blends based on plastic waste and natural biodegradable polymers is an interesting strategy in view of environmental and technical concerns. This article investigates the structure, thermal and physical properties of virgin and post‐industrial polymethyl methacrylate (PMMA) waste/pristine chitosan (Cs) bio‐blends. Waste PMMA was generated by an extrusion process for the manufacturing of sheets. The results of gel permeation chromatography analysis (GPC) show a slight decrease (about 8%) in the average molecular weight of PMMA after extrusion. Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR‐ATR) spectra do not reveal changes in the chemical structure of post‐industrial PMMA/Cs blends compared to virgin PMMA/Cs samples, indicating that chain scission reactions are the dominant degradation mechanism of PMMA during processing. Dynamic mechanical analysis (DMA) results reveal a single glass transition temperature (Tg) for the blends, implying miscibility of the components. Post‐industrial PMMA/Cs samples exhibit slightly lower values of Tg compared to virgin PMMA/Cs blends. The post‐industrial PMMA waste slightly reduces nano‐mechanical properties and thermal stability of the blends relative to those from virgin PMMA. In contrast, it increases the water uptake of the bio‐blends compared with virgin PMMA. Highlights: Chain scission is the dominant degradation mechanism of PMMA during extrusion.Miscibility between the homopolymers within the blends.PMMA waste slightly reduced the nano‐mechanical properties of the bio‐blends.Post‐industrial PMMA waste increased the water uptake of the bio‐blends.Possibility of using post‐industrial PMMA waste by blending with chitosan. [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/mm2. 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/mm2 to nearly 46 MPa, 18.2%, and 31.2 kJ/mm2, 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. [ABSTRACT FROM AUTHOR]

This paper is a follow-up to a previous work where we defined and generated the set of all possible compromises of multilevel multiobjective linear programming problems (ML-MOLPP). We introduce a new algorithm to solve ML-MOLPP in which the adaptive method of linear programming is nested. First, we start by generating the set of all possible compromises (set of all non-dominated solutions). After that, an algorithm based on the adaptive method of linear programming is developed to select the best compromise among all the possible settlements achieved. This method will allow us to transform the initial multilevel problem into an ML-MOLPP with bonded variables. Then, apply the adaptive method which is the most efficient to solve all the multiobjective linear programming problems involved in the resolution process instead of the simplex method. Finally, all the construction stages are carefully checked and illustrated with a numerical example. [ABSTRACT FROM AUTHOR]

This paper is a follow-up to a previous work where we defined and generated the set of all possible compromises of multilevel multiobjective linear programming problems (ML-MOLPP). We introduce a new algorithm to solve ML-MOLPP in which the adaptive method of linear programming is nested. First, we start by generating the set of all possible compromises (set of all non-dominated solutions). After that, an algorithm based on the adaptive method of linear programming is developed to select the best compromise among all the possible settlements achieved. This method will allow us to transform the initial multilevel problem into an ML-MOLPP with bonded variables. Then, apply the adaptive method which is the most efficient to solve all the multiobjective linear programming problems involved in the resolution process instead of the simplex method. Finally, all the construction stages are carefully checked and illustrated with a numerical example. [ABSTRACT FROM AUTHOR]

The effect of gamma irradiation on neat Polyamide-11 (PA11) and PA11 filled with 3 wt% of halloysite nanotubes (HNTs) was investigated at various doses up to 100 kGy in air and at room temperature. The irradiation test was conducted on sample films prepared by a twin-screw extruder in the first step then cast extrusion. The study showed the formation of a maximum of gel fraction up to 10 and 20 kGy for neat PA11 and PA11/HNTs, respectively. Furthermore, the results indicated the occurrence of crosslinking at low irradiation dose, whereas chain scission took place at higher ones. Additionally, the results revealed that the presence of HNTs limits the impacts of gamma irradiation through a barrier effect. An optimum irradiation dose was found for thermal and mechanical properties, corresponding to the dose for maximum gel formation. Moreover, experimental design was implemented to highlight the main incidences and interactions of both halloysite incorporation and radiation dose on some relevant effects of gamma irradiation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Green biocomposites based on poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) reinforced with Agave Americana fibers (AAF) were elaborated by melt compounding at various fiber content ratios, that is, 10, 20, and 30 wt.%. Morphology before and after tensile testing, rheological, viscoelastic, mechanical, and thermal properties of the biocomposite samples were investigated with respect to the AAF content. Tensile and DMA data showed a significant increase in both Young's modulus and storage modulus of PHBHHx biocomposites with the AAF content, however, more relevant at 30 wt.%. However, a slight decrease in tensile strength and strain at break was observed, while thermal stability remained almost unchanged whatever the AAF content. The study highlighted the reinforcement effect of AAF in PHBHHx biocomposite materials, in particular at filler content of 30 wt. %. Graphical Abstract [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]

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 effect of various clays nanofillers on the photo‐oxidation of polyamide 11 (PA11) has been investigated by accelerated ultraviolet (UV) test up to 780 h. Organo‐modified montmorillonite, halloysite nanotubes, and sepiolite were selected and incorporated separately to PA11 at 5 wt.%. The samples were prepared by melt compounding. Fourier transform infrared (FTIR) data showed a linear increase of carbonyl index (CI) in the first 360 h of exposure indicating a rapid oxidation of all samples without any induction period. Further, the nanocomposite samples exhibit faster oxidation kinetics than PA11, being however less pronounced for PA11/sepiolite. This is consistent with both the yellowing index (YI) evolution determined by UV–Vis spectroscopy and also the onset oxidation temperature (OOT) determined by differential scanning calorimetry (DSC). [ABSTRACT FROM AUTHOR]

In this work, the main objective is to investigate the effect of olive husk flour (OHF) used as a biofiller on the marine degradation of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) biocomposites up to 6 months of immersion in sea water at 25°C and 40°C. Film samples based on neat PHBV and PHBV are filled with 20 wt.% OHF is prepared by melt compounding. After 6 months of immersion in sea water, the study reveals a noticeable decrease in the absorption band intensity of ester groups of PHBV through Fourier transform infrared (FTIR‐ATR) spectroscopy, even more in the presence of OHF in PHBV biocomposite due to hydrolytic degradation. This phenomenon is, however, more pronounced at 40°C. This also agrees with differential scanning calorimetry (DSC) data, which indicates a large increase in crystallinity index (Xc) resulting from short chains reorganization. Moreover, scanning electron microscopic (SEM) analysis shows for both degraded samples, eroded and cracked surfaces, being however more pronounced for PHBV/OHF biocomposite at 40°C. This study highlights the role of OHF as a promotor of marine degradation of PHBV. [ABSTRACT FROM AUTHOR]

Hygrothermal aging of neat poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and PHBV filled with an organomodified montmorillonite (C30B) at 3wt. was investigated at 65°C and 100% relative humidity (RH) up to 100 days. FT‐IR data indicated that the carbonyl intensity index decreased with exposure time for both samples, while the main degradation mechanism occurred through hydrolysis reaction. This led to chain scissions resulting in a decrease in molar mass. Water absorption increased with exposure time for both neat PHBV and PHBV/C30B (3wt%) bionanocomposite. Differential scanning calorimetry measurements showed a decrease in both crystallinity index and melting temperature after hygrothermal aging and thermogravimetric analysis data indicated also a decrease in thermal stability. Mechanical and viscoelastic properties were also altered, being, however, more pronounced for the neat PHBV. Overall, the PHBV bionanocomposite exhibited a better resistance toward hygrothermal aging at 65°C and 100% RH. [ABSTRACT FROM AUTHOR]

The article reports some experimental data on the effects of three types of clay: organo-modified montmorillonite (cloisite 30B (C30B)), sepiolite (SP9), and halloysite nanotubes (HNT) on the morphology and physicomechanical properties of polycaprolactone (PCL)/clays bionanocomposites prepared by melt compounding. The clays were incorporated separately into the PCL matrix at a loading rate of 5.00 wt%, which corresponds to 2.91 ± 0.53, 2.42 ± 0.02, and 2.68 ± 0.13 vol% for C30B, SP9, and HNT, respectively. Scanning electron microscopy analysis showed good dispersion of both C30B and SP9 in the polymer matrix, while the presence of a few HNT aggregates was observed on the fracture surface of the PCL bionanocomposite. Furthermore, the HNT aggregates were randomly dispersed. The results indicated an enhancement of the rheological and tensile properties of the PCL bionanocomposite samples filled with C30B and SP9 compared to those containing HNT. Indeed, it was shown an increase in Young's modulus of PCL from 450 ± 16 MPa to 563 ± 42 MPa, 645 ± 68 MPa, and 502 ± 66 MPa for PCL bionanocomposites loaded with C30B, SP9, and HNT, respectively. On the other hand, the thermal stability of the whole PCL bionanocomposite samples was reduced being, however, more pronounced for those containing HNT. The decomposition temperature recorded at 5.00 wt% loss (T 5%) indicated 384.7 ± 0.9 for neat PCL, while the PCL bionanocomposites filled with C30B, SP9, and HNT exhibited the values of 357.3 ± 0.5, 353.2 ± 0.9, and 368.4 ± 0.4, respectively. [ABSTRACT FROM AUTHOR]

The effects of thermo-mechanical recycling through repeated extrusion cycles on morphology and properties of neat ethylene vinyl acetate copolymer (EVA) and EVA/olive husk flour (OHF) composites (70/30 w/w) with and without ethylene–butyl acrylate–glycidyl methacrylate (EBAGMA) compatibilizer were investigated in a single screw extruder machine up to five repeated cycles. The study showed that no significant modifications in the properties of the virgin EVA/OHF composite were observed along the recycling and this stability was further enhanced in the presence of EBAGMA. Indeed after five repeated extrusion cycles, the chemical structure and properties of both uncompatibilized and compatibilized composites remained unchanged compared to the neat polymer, which was subjected likely to cross-linking, in the fifth cycle. Furthermore, SEM analysis showed a better dispersion of OHF particles in EVA matrix and a good filler–polymer interfacial adhesion, being, however, more pronounced for the compatibilized composite. [ABSTRACT FROM AUTHOR]

Accelerated photooxidation under ultraviolet (UV) test of polyamide 11 (PA11) films filled with unmodified vermiculite clay at 5 wt% was investigated up to 600 h. Film samples of ~60‐μm thick were prepared by melt compounding using a cast extruder and exposed to UV light irradiation at λ > 295 nm. Fourier transform infrared (FTIR) spectra indicated similar structural changes occurring in both PA11 and PA11/unmodified vermiculite nanoclay (UVMC) nanocomposite along the photooxidation process, resulting in imides and carboxylic acids as the main carbonyl products. It was however observed that the formation rate of carbonyls in the PA11/UVMC nanocomposite was slower than neat PA11. This behavior is consistent with the yellowing index evolution determined by ultraviolet–visible (UV–vis) spectroscopy. Further, the photooxidation stability of the samples was also evaluated by the onset oxidation temperature determined by differential scanning calorimetry. The results indicated a better stability of the nanocomposite film than neat PA11, corroborating well the data obtained by FTIR and UV–vis techniques. POLYM. ENG. SCI., 59:2449–2457, 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Biocompostable composites based of ethylene‐co‐vinyl acetate (EVA) copolymer were prepared by using a twin‐screw extruder. The compatibility between EVA/starch composites were improved either by addition of polyethylene‐grafted maleic anhydride (PE‐g‐MA), or by reactive extrusion with maleic anhydride (MA) and benzoyl peroxide. The crystallinity of the non‐compatibilized composites increased with the starch content. The addition of PE‐g‐MA increased the crystallinity of the composites made with up to 20 wt% of starch. The thermal stability of EVA/starch composites decreased with increasing the starch content, and the addition of PE‐g‐MA compatibilizer enhanced the thermal stability of the composite. The in‐situ grafting with MA and PBO led to an increase in the thermal stability of the composites containing higher amounts of starch. Further, the mechanical properties of the compatibilized EVA/starch composites were improved with increasing the starch content and this was ascribed to the improved interfacial interactions between starch and EVA. POLYM. COMPOS., 40:3242–3253, 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Halloysite nanotubes (HNTs) were successfully incorporated as flame retardants in polyamide‐11 (PA11) after their modification with methyl phosphonic acid. Fourier transform infrared spectroscopy, thermal gravimetric analysis (TGA) and pyrolysis–gas chromatography–mass spectrometry were used to evidence the functionalization of the clay. Raw and modified HNTs were then incorporated by melt mixing in PA11 at 20 wt%. Compositions containing both ammonium polyphosphate (APP) and HNTs were also prepared. TGA and pyrolysis combustion flow calorimeter exhibited enhancement in thermal stability upon incorporation of both raw and modified halloysite nanotubes while APP causes degradation at lower temperature. Cone calorimeter data showed that modified halloysite acts by forming an insulating barrier during the combustion, which limits heat and mass transfers. Moreover, elemental analysis of sample residues after cone test evidenced that a part of the phosphorus of the modified halloysite was transferred to the gaseous phase. These results suggest the full potential of halloysite as fire retardant agent for polyamides. POLYM. ENG. SCI., 59:526–534, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This article reports some morphological, tribological, and mechanical data on polyamide-11(PA11)/halloysite nanotube (HNT) nanocomposites prepared by melt-compounding. HNTs extracted from the Djebel Debbagh deposit in Algeria were incorporated into the polymer at 1, 3, and 5 wt%. For comparison, commercial HNTs were also used under the same processing conditions. Scanning electron microscopy showed that both HNTs were homogeneously dispersed in the PA11 matrix, despite the presence of few aggregates, in particular at higher filler contents. The tribological properties were significantly improved, resulting in a decrease in the friction coefficient and the wear rate characteristics due to the lubricating effect of HNTs. This is consistent with optical profilometry data, which evidenced the impact of both types of HNTs on the surface topography of the nanocomposite samples, in which the main wear process was plastic deformation. Furthermore, Young's modulus and tensile strength were observed to increase with the filler content, but to the detriment of elongation at break and impact strength. Regarding the whole data, the raw Algerian halloysite led to interesting results in PA11 nanocomposites, thus revealing its potential in polymer engineering nanotechnology. [ABSTRACT FROM AUTHOR]

In this study, biocomposites of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx)/cellulose microcrystalline (MCC) extracted from olive husk flour are prepared by melt compounding at various filler content ratios, i.e., 10, 20, and 30 wt%. The effect of the MCC content on the morphology, thermal stability, crystallinity, and water uptake of the PHBHHx biocomposites is investigated. The results showed that the addition of MCC to PHBHHx decreased the thermal stability of the biocomposites compared to that of neat polymer, however more pronounced at a higher filler content. This is due probably to the tendency of MCC particles to agglomerate, inducing heterogeneities and defects within the polymer matrix observed by scanning electron microscopy. Furthermore, both crystallinity and water uptake after 24 h of immersion increased with the filler content. [ABSTRACT FROM AUTHOR]

Polyamide 11‐based bionanocomposites were prepared by melt compounding with 10 wt% clays of different chemistry and morphology. This included vermiculite nanoflakes obtained by consecutive thermal and ultrasonic exfoliation in both neat and organo‐modified form. The mechanical reinforcement‐ and flame‐retardant performance of the vermiculite clays were compared to organo‐modified montmorillonite (Cloisite 30B) and needle‐shaped sepiolite (Pangel S9). Electron microscope investigations revealed different structures and dispersion levels of the clay nanoparticles in the polymer matrix. Tensile tests showed that the addition of clays led to considerable improvements in Young's modulus without compromising the elongation at break. Compared to the neat polymer, all clays reduced the peak heat release rate and the smoke production rate in cone calorimeter testing. Surprisingly, the needle‐shaped sepiolite clay and the two vermiculites outperformed the montmorillonite organoclay in the fire testing even though it featured the highest degree of exfoliation in the polymer matrix. POLYM. ENG. SCI., 58:1746–1755, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Abstract: In this study, multifilament fibers based on neat poly(lactic acid) (PLA), PLA/cellulose nanowhiskers (CNWs), and PLA/cellulose microcrystalline (MCC) loaded at 1 and 3 wt.% were prepared by melt‐spinning process in the presence of PLA‐grafted maleic anhydride (PLA‐g‐MA) used as the compatibilizer and PEG as the plasticizer. This study showed that the incorporation of MCC in PLA matrix whatever the loading rate was not suitable for multifilament fibers spinning compared with CNW, due to the restricted drawability and a poor dispersion of the MCC within the PLA matrix. Furthermore, the whole characterization studies indicated that the incorporation of 1 wt.% of CNW in PLA with addition of the compatibilizer led to better thermal stability, flame retardancy, and multifilament tensile properties compared with neat PLA and with other filled PLA multifilament fibers. [ABSTRACT FROM AUTHOR]

The asymmetry of halloysite surface chemistry was used to perform a selective modification of its inner surface via grafting of a synthesized styrene/(methacryloyloxy)methyl phosphonic acid copolymer. Fourier transform infrared spectroscopy, thermogravimetric analysis ( TGA) and pyrolysis gas chromatography/mass spectrometry were used to evidence and quantify the grafting. Then, raw and hybrid nanoparticles were incorporated in polystyrene ( PS)/polyamide-11 ( PA11) blends (80/20 and 60/40 wt%). Scanning electron micrographs showed differences in localization of the halloysite nanotubes ( HNTs), since raw halloysite is concentrated in the PA11 phase while modified halloysite is also located at the PS/ PA11 interface, leading to a better interfacial adhesion between PS and PA11. An inhibiting effect of modified halloysite on PA11 coalescence was evidenced by measuring the particle size distribution of the extracted nodules. Moreover, the presence of modified halloysite at the interface shows an improvement in terms of thermal stability as observed by TGA, but with no significant effects on PA11 crystallization behaviour as shown by differential scanning calorimetry results. Rheological measurements were carried out to study the influence of the surface modification of halloysite on the blend morphology. A gel-like behaviour was observed for the (60/40 wt%) HNTs reinforced composition that was enhanced in the case of 10% functionalized halloysite. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The paper provides some experimental data on the effects of a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) grafted maleic anhydride (PHBV-g-MA) used as the compatibilizer for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/olive husk flour (OHF) composites prepared by melt compounding. The natural filler was added to PHBV at various contents, i.e. 10, 20, and 30 wt%, while the amount of PHBV-g-MA was 5 wt% based on neat PHBV. Morphology, contact angle measurements, water absorption (WA), mechanical, viscoelastic, and barrier properties of the various composites were investigated with and without the compatibilizer. The study showed through scanning electron microscopy that the addition of PHBV-g-MA to PHBV/OHF composites resulted in better and finer dispersion of the filler in the matrix, even at a higher content ratio, indicating improved affinity between the components. This is in agreement with the decrease in both surface energy and WA. Furthermore, tensile and dynamic mechanical measurements indicated a reinforcing effect of OHF in PHBV composites, being more pronounced in the presence of PHBV-g-MA. The barrier properties against oxygen and water vapor were also improved for the compatibilized composites. [ABSTRACT FROM AUTHOR]

ABSTRACT The degradation of uncompatibilized and compatibilized PP/PA-6 (70/30 wt %) with PP- g-MA under accelerated UV light was investigated using Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy, melt flow index (MFI) tester, tensile test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). FTIR analysis of the structure of the compatibilized and uncompatibilized blends after exposure to UV light showed the formation of photoproducts corresponding to both components. The MFI and mechanical results obtained revealed that photooxidation started primarily in PA-6 rather than PP. In addition, the uncompatibilized blends exhibited a higher degradation rate compared to neat polymers for long exposure time, and the addition of PP- g-MA increased slightly their ageing rate in accordance with TGA data. Further, DSC analysis showed an increase in the crystallinity index and a decrease in the melting temperature of PP and PA-6 after UV exposure either as neat polymers or as blend components. SEM micrographs of the cryo-fractured surfaces of the samples illustrated the formation of cracks and fractures after UV irradiation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41722. [ABSTRACT FROM AUTHOR]

The hydrothermal degradation at 90°C in distilled water of metallocene linear low density polyethylene films (mLLDPE) has been studied using low density polyethylene (LDPE) for comparison. FTIR spectroscopy, DSC and chemiluminescence techniques were used for investigation of the hydrothermal ageing-induced changes. The stabilization effect of a commercially available HALS, namely Sanduvor PR 31, able to graft on polyolefin structures has been also studied, as well. It was found that intense oxidation process occurs in the case of LDPE: hydroxyl, carbonyl and unsaturated groups were identified in FTIR spectra. mLLDPE reference films presented considerably higher stability as compared to LDPE ones, this behaviour being assigned to the structural peculiarities. Sanduvor PR 31 induced higher stability in LDPE, possibly by grafting mechanism, but it did not present a significant effect in the case of mLLDPE. Besides a possible antagonist interaction with the process stabilizer or a graft-hindering effect of the alkyl side groups, the intrinsic higher stability of the mLLDPE which offers less active sites for grafting could be supposed to explain this lower effectiveness. [ABSTRACT FROM AUTHOR]

The effects of recycling cycles (up to six repeated cycles) on the structure and properties of neat poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), neat polylactide (PLA) and PHBV/PLA: 50/50 (wt%) blends elaborated by melt molding process were investigated. The changes in the chemical structure, the morphology and the thermal, mechanical and rheological properties of the recycled materials were studied. The reduction of molecular weights of both PHBV and PLA showed the predominance of chain scission mechanism as a result of degradation inducing an enhancement of PHBV chain mobility, as also revealed by the increasing of the PHBV crystallinity measured using differential scanning calorimetry and wide angle X-ray scattering. Nevertheless, all these effects were significantly smaller for neat PLA and PHBV-PLA blends compared to those of neat PHBV. Contrary to PLA, PHBV seems to be relatively more sensitive to the thermomechanical degradation and the presence of PLA in the PHBV-PLA blend tends to partially prevent the degradation of PHBV. Mechanical results evidenced the great recyclability of PHBV/PLA blends, even after six reprocessing cycles, since the values of mechanical characteristics remain more or less constant compared to the initial ones revealing the preservation of the material mechanical properties. A stabilizing effect of PLA on the recyclability of PHBV-PLA blends was highlighted and it can be concluded that the incorporation of PLA in PHBV/PLA blends might be a promising route to extend the PHBV applications. [ABSTRACT FROM AUTHOR]

Blends of poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV) and polylactide (PLA) with different PHBV/PLA weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) were prepared by melt compounding. To improve the miscibility between the two components of the blend, low amount of compatibilizing agent (5 wt%), obtained by grafting maleic anhydride onto PHBV, was used. When compared with the uncompatibilized blends, the compatibilizer presence induces a greater interfacial adhesion. The effect of Cloisite 30B (C30B) on the blend morphology and the blend properties was also investigated. The morphology of the different blends as well as the evolution of their material properties were discussed in terms of the nanoclay and compatibilizing agent contents. A synergistic effect of compatibilizer and C30B was highlighted leading to an improved miscibility of the two blend components. The resulting properties were correlated with the morphology observed for the different blends. POLYM. ENG. SCI., 54:2239-2251, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Blends of poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV) and polylactide (PLA) with different PHBV/PLA weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) were prepared by melt compounding. Their mutual contributions in terms of thermal stability, flammability resistance, mechanical properties and rheological behavior were investigated. The study showed that the increase in PLA content in PHBV/PLA blends leads to enhanced properties. Consequently, thermal stability and flammability resistance were improved. Further, the rheological measurements indicated an increase in storage modulus and loss modulus of PHBV matrix by addition of PLA. [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]

This work aims to study the effects of date stone flour (DSF) on morphology, thermal, and mechanical properties of polypropylene (PP) composites in the absence and presence of ethylene-butyl acrylate-glycidyl methacrylate (EBAGMA) used as the compatibilizer. DSF was added to the PP matrix at loading rates of 10, 20, 30, and 40 wt %, while the amount of compatibilizer was fixed to the half of the filler content. The study showed through scanning electron microscopy analysis that EBAGMA compatibilizer improved the dispersion and the wettability of DSF in the PP matrix. Thermogravimetric analysis (TGA) indicated a slight decrease in the decomposition temperature at onset ( Tonset) for all composite materials compared to PP matrix, whereas the thermal degradation rate was slower. Differential scanning calorimetry (DSC) data revealed that the melting temperature of PP in the composite materials remained almost unchanged. The nucleating effect of DSF was however reduced by the compatibilizer. Furthermore, the incorporation of DSF resulted in the increase of stiffness of the PP composites accompanied by a significant decrease in both the stress and strain at break. The addition of EBAGMA to PP/DSF composites improved significantly the ductility due to the elastomeric effect of EBAGMA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

PS/organo-modified clay (5% w/w) nanocomposite has been subjected to a series of eight processing cycles in a twin screw extruder. The influence of multiple recycling on the properties of the nanocomposite was studied by following the changes in the morphology, the molecular structure, the melt flow index (MFI) and the thermal properties. The WAXS results indicate a strong intercalation of PS chains between silicate layers of the organoclay and the extent of intercalation appears to increase with increasing the number of cycles. The main effects of recycling are a reduction in molecular weight due to chain scission, although the occurrence of a crosslinking fraction is probable after 8 cycles. The thermal properties remain almost stable during reprocessing. [ABSTRACT FROM PUBLISHER]

The paper reports some results of an experimental study on ethylene vinyl acetate (EVA) copolymer/olive husk flour (OHF) composites incorporated at various filler ratios (15, 30 and 45 wt%) in the absence and the presence of ethylene-butyl acrylate-glycidyl methacrylate (EBAGMA) terpolymer used as a compatibilizer. The composite samples have been prepared by melt blending and their chemical structure, as well as morphological, mechanical and water absorption properties investigated. It is shown that the compatibility of EVA/OHF composites is improved by the addition of EBAGMA terpolymer. Indeed, FT-IR analysis shows that chemical interactions have occurred between the compatibilizer and the base blend components. Morphological results from SEM shows better dispersion of the wood particles in the EVA matrix and the resulting composite samples exhibit better tensile properties at break and lower water absorption than the uncompatibilized ones. Moreover, the results indicate that the loading concentrations of both OHF and EBAGMA have an effect on the composite properties. [ABSTRACT FROM AUTHOR]

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The olive pomace was modified chemically to improve the interface between the polymer matrix and the cellulosic fillers. The modification was done using various ester types having the same nature, however, with different chain lengths and one silane. Before the surface treatment, the olive pomace was extracted with acetone to remove contaminants on the surface, using Soxhlet apparatus. The transesterification of olive pomace with the different ester components, i.e., vinyl acetate, vinyl propanoate, and vinyl butanoate, and the condensation reaction with dichlorodimethylsilane was confirmed by Fourier transform infrared (FTIR) analysis. Moreover, the treatment of olive pomace with vinyl acetate improves the thermal stability and the sample records higher onset temperature of degradation as measured by thermogravimetric analysis (TGA). The results obtained indicated also that the reaction between the hydroxyl groups of waste flour and the acetyl, propionyl, pivalyl, and silane groups have occurred. The modified wood flours exhibited a decrease in the hydrophilicity as supported by the lower moisture content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

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.