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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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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.