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Intrinsic viscosity, zero-shear viscosity and average molecular weight of the neat PLA and the PLA/OSW biocomposites
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A new valorization strategy for Olive Solid Waste (OSW) has been carried out consisting in incorporating this biomass as filler in a biopolymer matrix. In this study, biocomposites based on poly(d,l-lactide) (PLA) and OSW fillers were prepared with various filler contents. It was highlighted that the inclusion of OSW under high temperatures resulte...
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Context 1
... PLA K ' value is 0.3, indicating that the chloroform is a good solvent for this polyester. As it can be seen in Table 2, the intrinsic viscosity value decreased from 161 mL/g for unprocessed PLA to 153 mL/g for the extruded PLA. Then, the value dropped to 112 mL/g for PLA extracted and filtered from PLA/ OSW (80/20) biocomposite. ...Context 2
... viscosity-average molecular weights (M v ) calculated using the MHS equation (Eq. 5), are reported in Table 2. Furthermore, we evaluate a parameter K 000 (Eq. 6) as the degradation factor [27]. ...Context 3
... M v(pellets) is the viscosity average molecular weight of pristine PLA and M v(processed polymer) is either the viscosity average molar mass of processed neat PLA or processed PLA/OSW biocomposite. It is worth noting that K 000 value increased for the PLA extracted from the biocomposite as compared to the neat processed PLA thus indicating a decrease of its viscosity average molecular weight (Table 2). Moreover, the calculated values show that the average molecular weight of PLA slightly decreases after melt processing (from 184.000 to 172.000 g/mol). ...Similar publications
Twenty Kaissy variety extra virgin olive oil samples collected from research centre field near Damascus were analyzed by gas chromatography using a flame ionization detector. Fifteen sterols fractions were identified and determined their concentrations: cholesterol, brassicasterol, 24-metilencholesterol, campesterol, campestanol, stigmasterol, Δ7-...
Citations
... The polarity difference between natural fillers and polymeric matrix creates significant scientific challenges in creating high-performance green composites for widespread applications [22]. Up to now for improving the performance of the green composites several methodologies have been used including physical modification such as the addition of plasticizer [23], alkali or silane chemical treatment of the fibers [24,25], use of maleic anhydride grafted polymer [26,27] and use of compatibilizers such as peroxide or multifunctional epoxide agent [28,29]. Hydrophobic PBS and PLA, with hydroxyl and carboxyl end groups, and hydrophilic starch and wheat straw with plenty of hydroxyl groups are thermodynamically immiscible due to the difference in chemical structure and behavior and present poor interfacial adhesion. ...
Disposable containers made of non-biodegradable polymers are considered as one of the most prevalent environmental pollutants. It is very important and desirable to make fully biodegradable disposable containers for food packaging that does not endanger the health of consumers. In this research, fully biodegradable polymer composites were prepared by melt mixing of polylactic acid (PLA), polybutylene succinate (PBS), and natural polymers including corn starch and wheat straw, and their physical and mechanical properties were evaluated. For this purpose, by conducting experiments according to the optimal custom mixture design of the response surface methodology, the effect of 3 independent variables including the concentration of the PLA and PBS biopolymers blend (50/50% w/w) (CBB) in the range of 30–70, the concentration of corn starch (CCS) in the range of 30–60 and the concentration of wheat straw (CWS) in the range of 0–8 wt percentage of biocomposite on the dependent variables including the elastic modulus (EM), elongation at break (EB), impact strength (IS) and equilibrium moisture content (EMC) of the biocomposite sheet were investigated. According to the results of this research, with the increase in the concentration of corn starch and wheat straw in the studied range, the EM and EMC of the biocomposite increased, while its EB and IS decreased. According to the results obtained from optimizing the effects of independent variables on the physicomechanical properties of the biocomposite sheet, the optimal values predicted by the models for CBB, CCS and CWS were 48.2 wt%, 45.4 wt%, and 6.4 wt%, respectively and predicted values for EM, EB, IS and EMC were 80.8 MPa, 11.4%, 2 kJ/m2 and 4.1%, respectively. Also, the biodegradability rate of the biocomposite with the optimal formulation was 71.1% in the fifth month of the test.
... In a recent study [15], biocomposites made from polylactic acid (PLA) and olive solid waste (OSW) were developed, with the aim to minimize fabrication costs and reduce waste from the olive oil industry. It was demonstrated that the OSW inclusion under high temperatures resulted in a degradation of the PLA matrix. ...
... The complex viscosity modulus of the PLA-20% OSW biocomposite was lower than that of the neat PLA. In fact, the presence of hydroxyl groups in the hydrophilic OSW filler favored alcoholysis or hydrolysis of the PLA matrix, which could be responsible for the higher losses of molar masses in the PLA/OSW biocomposites compared with the neat PLA [15]. However, the incorporation of ACR into the PLA/OSW biocomposite significantly raised the viscosity with increasing coreshell particle content (Fig. 4a). ...
... The storage modulus of the biocomposite without ACR was lower than that of the neat extruded PLA. This can obviously be explained by the PLA degradation process in the presence of OSW [15]. However, the incorporation of ACR into the PLA/OSW biocomposites significantly raised the elastic modulus G 0 when increasing the CS (ACR) amount. ...
Biocomposites from polylactic acid (PLA) and olive solid waste (OSW) were melt-blended with core–shell acrylate rubber particles (ACR) in order to enhance the thermal stability upon melt processing and the mechanical performances of these biocomposites, thereby expanding their area of application. Dynamic mechanical analysis indicated that the ACR particles imparted more flexibility to the PLA/OSW biocomposites and thermal analysis showed that the incorporation of ACR significantly restrained the ability of the PLA chains to crystallize. The values of complex viscosity and storage modulus were significantly increased with the introduction of ACR. These results could be assigned to the entanglements between the PLA chains and those of the ACR shell, giving rise to a physical network that limited the segmental mobility of PLA and induced a high melt elasticity. Mechanical tests revealed that the elongation at break and the impact strength of the biocomposites were considerably improved. Moreover, morphological observations showed a clear adhesion enhancement between the PLA matrix and the OSW fillers in the presence of the ACR additive. POLYM. ENG. SCI., 2017.
The rheological properties of biocomposites can change depending on the polymer, fiber type, fiber size and processing conditions. In this work, biodegradable PBS composites filled with raw and enzymatically treated date palm fibers were processed using an internal mixer. The influence of the processing conditions, namely filler concentration, rotor of the mixer rotational speed, as well as the type of the enzymatic fiber treatment on PBS (Poly Butylene Succinate)/date palm fiber composites were studied by measuring the torque and the temperature in real time during melt processing. A rheological analysis was also carried out by performing time and multi-wave-frequency sweeps. It was found that the stabilization torque increased with increasing fiber loading and rotor rotational speed, indicating a higher viscosity. An enhancement of the melting process occurred with modified fibers, which was explained by the decrease in the fiber diameter, denoting cellulose micro-fibrils separation by enzymes action. These composites were characterized by a better thermal resistance and mechanical stiffness compared to those based on raw fibers at the same loading rate.
Biocomposites containing natural fibers and biopolymers are an ideal choice for developing substantially biodegradable materials for different applications. Polylactic acid is a biopolymer produced from renewable resources and has drawn numerous interest in packaging, electrical, and automotive application in recent years. However, its potential application in both electrical and automotive industries is limited by its flame retardancy and thermal properties. One way to offset this challenge has been to incorporate natural or synthetic flame retardants in polylactic acid (PLA). The aim of this article is to review the trends in research and development of composites based on agricultural fibers and PLA biopolymers over the past decade. This article highlights recent advances in the fields of flame retardancy and thermal stability of agricultural fiber-reinforced PLA. Typical fiber-reinforced PLA processing techniques are mentioned. Over 75% of the studies reported that incorporation of agricultural fibers resulted in enhanced flame retardancy and thermal stability of fiber-reinforced PLA. These properties are further enhanced with surface modifications on the agricultural fibers prior to use as reinforcement in fiber-reinforced PLA. From this review it is clear that flame retardancy and thermal stability depends on the type and pretreatment method of the agricultural fibers used in developing fiber-reinforced PLA. Further research and development is encouraged on the enhancement of the flame retardancy properties of agricultural fiber-reinforced PLA, especially using agricultural fibers themselves as flame retardants as opposed to synthetic flame retardants that are typically used.
Currently, food waste is a major concern for companies, governments, and consumers. One of the largest sources of food waste occurs during industrial processing, where substantial by-products are generated. Fruit processing creates a lot of these by-products, from undesirable or “ugly fruit,” to the skins, seeds, and fleshy parts of the fruits. These by-products compose up to 30% of the initial mass of fruit processed. Millions of tons of fruit wastes are generated globally from spoilage and industrial by-products, so it is essential to find alternative uses for fruit wastes to increase their value. This goal can be accomplished by processing fruit waste into fillers and incorporating them into polymeric materials. This review summarizes recent developments in technologies to incorporate fruit wastes from sources such as grape, apple, olive, banana, coconut, pineapple, and others into polymer matrices to create green composites or films. Various surface treatments of biofillers/fibers are also discussed; these treatments increase the adhesion and applicability of the fillers with various bioplastics. Lastly, a comprehensive review of sustainable and biodegradable biocomposites is presented.
