Environment friendly, renewable and sustainable poly lactic acid (PLA) based natural fiber reinforced composites – A comprehensive review

Highly stretchable strain sensors based on conducting polymer hydrogel are rapidly emerging as a promising candidate toward diverse wearable skins and sensing devices for soft machines. However, due to the intrinsic limitations of low stretchability and large hysteresis, existing strain sensors cannot fully exploit their potential when used in wearable or robotic systems. Here, a conducting polymer hydrogel strain sensor exhibiting both ultimate strain (300%) and negligible hysteresis (<1.5%) is presented. This is achieved through a unique microphase semiseparated network design by compositing poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) nanofibers with poly(vinyl alcohol) (PVA) and facile fabrication by combining 3D printing and successive freeze‐thawing. The overall superior performances of the strain sensor including stretchability, linearity, cyclic stability, and robustness against mechanical twisting and pressing are systematically characterized. The integration and application of such strain sensor with electronic skins are further demonstrated to measure various physiological signals, identify hand gestures, enable a soft gripper for objection recognition, and remote control of an industrial robot. This work may offer both promising conducting polymer hydrogels with enhanced sensing functionalities and technical platforms toward stretchable electronic skins and intelligent robotic systems.

High‐Stretchability, Ultralow‐Hysteresis ConductingPolymer Hydrogel Strain Sensors for Soft Machines

Recent advances in TiO2-functionalized textile surfaces

Advancements in polymer science and engineering have helped the scientific community to shift its attention towards the use of environmentally benign materials for reducing the environmental impact of conventional synthetic plastics. Biopolymers are environmentally benign, chemically versatile, sustainable, biocompatible, biodegradable, inherently functional, and ecofriendly materials that exhibit tremendous potential for a wide range of applications including food, electronics, agriculture, textile, biomedical, and cosmetics. This review also inspires the researchers toward more consumption of biopolymer-based composite materials as an alternative to synthetic composite materials. Herein, an overview of the latest knowledge of different natural- and synthetic-based biodegradable polymers and their fiber-reinforced composites is presented. The review discusses different degradation mechanisms of biopolymer-based composites as well as their sustainability aspects. This review also elucidates current challenges, future opportunities, and emerging applications of biopolymeric sustainable composites in numerous engineering fields. Finally, this review proposes biopolymeric sustainable materials as a propitious solution to the contemporary environmental crisis. • Use of biopolymers has emerged as a new paradigm of the ecological conservation. • Biopolymeric composites are easily degraded under the possible source of degraded environment. • Biopolymers have found their applications in biomedical, food, electronics, cosmetics and other emerging fields. • Further understanding on their mode of action through this comprehensive review will imparts knowledge. 

Biopolymeric Sustainable Materials and their Emerging Applications

ABSTRACT Fused filament fabrication (FFF) is an additive manufacturing process, which constructs physical items by fused melt material, selectively deposited layer-by-layer through a heated extrusion mechanism. Parameters’ selection and control in FFF are of utmost importance since they significantly affect the surface quality (SQ) and dimensional accuracy (DA) of the FFF printed parts. In the present paper, initially, the FFF process is briefly presented. Next, a cause-and-effect diagram exhibits the process parameters’ categorization with the SQ and DA of the manufactured parts. Then, according to the robust design theory, the process parameters are divided into three classes, i.e., the signal, the control, and the noise. This classification supports the selection of appropriate FFF printers, according to the control parameters, whereas it facilitates the optimization of the SQ and DA of printed parts, concerning the signal parameters. Finally, the impact of each parameter on SQ and DA is presented, supported by an extensive literature review. Overall, the process parameters’ optimization is critical for the SQ and DA. Therefore, they should be adjusted to achieve higher quality and less post-processing work.

Key parameters controlling surface quality and dimensional accuracy: a critical review of FFF process

The advantages of green composites are including, but not limited to their environmental friendly nature, lightweight, reduction of production energy and costs, recyclability. This work focuses on the mechanical, thermal and dynamic mechanical properties of biocomposites. For that purpose biosourced polymers were used, namely polylactic acid (PLA) and sisal fiber, and biocomposites were extruded and then injection molded with different contents of sisal fibers (5%, 10%, 15%). The results show that the increase of the rate of reinforcement improves the mechanical and dynamic mechanical properties of the biocomposites made. By the increase of the sisal fiber content the degree of crystallinity of the matrix was increased from 47% to 61%, as sisal fibers were acted as a nucleating agent for the PLA.

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Mechanical and thermal characterization of sisal fiber reinforced polylactic acid composites

This work aims to investigate the physical and mechanical properties of sisal fiber and yarn of Moroccan origin The cellulosic and non-cellulosic constituents of the Moroccan sisal fiber were identified by FTIR spectroscopy The thermal properties were studied by thermogravimetric analysis The hydrophilicity of the fiber was evaluated by the contact angle The results show that the sisal fiber has a low thermal stability The mechanical properties of the fiber analyzed by the Impregnated Fiber Bundle Test (IFBT) method show that the porosity of the impregnated yarns and the twist angle of the yarns influence the elastic modulus of the sisal fiber The physical and mechanical properties of the manufactured sisal yarns were also characterized and analyzed The obtained results reveal an interesting potential to use the Moroccan sisal fiber in development of bio-sourced composite materials

https://www.mdpi.com/2079-6439/9/2/13/pdf

Identification of the Physical and Mechanical Properties of Moroccan Sisal Yarns Used as Reinforcements for Composite Materials

Various species of polysaccharides were extracted from algae collected from the west coast of Morocco. This area is known for its abundance of various species of algae. The polysaccharides of three species, Sargassum muticum, Cystoseira myriophylloides and Cystoseira baccata were selected and their rheological properties were evaluated at different concentrations (1, 3, 5, 7 and 9% by w/v) and in the temperature range from 10 to 60 °C. FTIR analysis of these polysaccharides was also carried out to identify the functional groups and its analysis revealed the presence of uronic acid groups. These polysaccharides showed non-Newtonian behavior. The evolution of the apparent viscosity as a function of shear rate was described by the power-law model. The values of the flow behavior index were less than unity at high concentration. The consistency coefficient greatly increased. The non-linearity was increased with concentration and it was characterized by a power law, basically for Cystoseira myriophylloides and Cystoseira baccata. Besides, the flow behavior temperature dependence was characterized by the Arrhenius model to extract the activation energy. The values of the activation energy were found between 11.28–13.76 kJ/mol, 15.29–17.67 kJ/mol, and16.83–17.98 kJ/mol for Sargassum muticum, Cystoseira baccata and Cystoseira myriophylloides, respectively.

Extraction of polysaccharides from brown algae: rheological studies

The rheological properties and spectrum infrared of polysaccharides extracted from Cystoseira myriophylloides algae were investigated in the concentrations range from 3 to 9% (w/v) and at different...

Rheological investigations of water-soluble polysaccharides extracted from Moroccan seaweed Cystoseira myriophylloides algae

Polyester (PET) was pre-activated by atmospheric air plasma and coated by various inorganic oxide nanoparticles (MOx) such as titanium dioxide (TiO2), zinc oxide (ZnO), and silicon oxide (SiO2), using poly(vinylidene fluoride) (PVDF) and chitosan (CT) as binders. The resulting PET-PVDF-MOx-CT composites were thermally compressed and then characterized by scanning electron microscopy, Fourier infrared spectroscopy, thermal gravimetric analysis, and flame retardancy (FR) ability tests. PET modifications resulted in more thermally stable and less harmful composites with weaker hazardous gas release. This was explained in terms of structure compaction that blocks pyrolysis gas emissions. CT incorporation was found to reduce the material susceptibility to oxidation. This judicious procedure also allowed improving flame retardancy ability, by lengthening the combustion delay and slowing the flame propagation. Chitosan also turned out to contribute to a possible synergy with the other polymers present in the synthesized materials. These results provide valuable data that allow understanding the FR phenomena and envisaging low-cost high FR materials from biodegradable raw materials.

Reddad El Moznine

Papers

Mechanical and thermal characterization of sisal fiber reinforced polylactic acid composites

Identification of the Physical and Mechanical Properties of Moroccan Sisal Yarns Used as Reinforcements for Composite Materials

Extraction of polysaccharides from brown algae: rheological studies

Rheological investigations of water-soluble polysaccharides extracted from Moroccan seaweed Cystoseira myriophylloides algae

Polyester-supported Chitosan-Poly(vinylidene fluoride)-Inorganic-Oxide-Nanoparticles Composites with Improved Flame Retardancy and Thermal Stability