Characterization of groundnut shell powder as a potential reinforcement for biocomposites

Natural fibers are becoming the right candidate material as a substitute for glass fibers in the reinforcement of plastic polymers for various applications. The ease of their processing with minimal energy consumption and the quest to produce biodegradable plastics with lightweight has given natural fibers comparative advantages over synthetic fibers. In this study, groundnut shell powder (GSP) in different forms (untreated, sodium hydroxide treated and ash) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray fluorescence (XRF), Nuclear magnetic resonance (NMR), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM) to evaluate their possible utilization as reinforcement in polymers. GSP was treated with sodium hydroxide for 5 hrs and dried in vacuum for 24 hrs to obtain treated GSP while ash GSP was formed by heating GSP in the furnace at 600 °C for about 3 hrs. The results reveal that sodium hydroxide treatment was very effective in the breaking down of the hydrogen bond with a consequent reduction in the hydrophilicity of the GSP. This would promote GSP bonding with the hydrophobic polymer matrix in the development of natural fiber reinforced plastic polymer composite materials. Ash GSP was found to have the highest crystallinity among the three forms of GSP based on XRD results. Therefore, the result achieved in this work confirmed that treated and ash GSP fibers are good reinforcement material in the production of polymer composites, with the actual choice depending on end-use property requirements of the composite.

Poultry feather disulphide bond breakdown to enable bio-based polymer production

With oil supplies, needed for plastic production, decreasing dramatically, there is a clear driver for alterative polymers from sustainable resources. Poultry feathers, containing ∼90% keratin, are one source of natural polymer with huge potential for biopolymer production. However, the presence of crosslinks, known as disulphide bonds, hinders processability. This paper reviews techniques to enable breakage of disulphide bonds through use of reduction agents (sodium sulphite and sodium sulphate) and hydrolysis. Samples were analysed using FTIR and DSC to quantify achievable bond breakage, effect on thermal properties and changes in protein concentration. A review on the effect of particle size on disulphide bond breakage was also conducted, along with quantifying the reformation of bonds post-processing. Finally, a bicinchoninic acid (BCA) protein assay was used to quantify changes to soluble protein content, key to predicting if biopolymer formation can occur. The results showed a final disulphide bond breakage of between 48% and 67% was achievable using these techniques. It was also shown that disulphide bond content exhibited up to 60% bond reformation post treatment. These reductions in disulphide bonds increased the thermoplastic nature and apparent protein content. Despite achieving the highest bond breakage percentage, hydrolysis caused degradation of useful proteins, rendering the material unsuitable for biopolymer production. Results suggested that treatment with sodium sulphite (4.3% wt. of feathers) and use of a small particle size (0–100 µm), sufficiently altered the properties of raw feathers to enable feather biopolymer production.

Chitosan-based films reinforced with cellulose nanofibrils isolated from Euterpe oleraceae MART

The use of local raw materials for the production of biodegradable films can simultaneously contribute to the development of the Amazon and global sustainability. This work aimed to evaluate the physical and mechanical performance of chitosan-based bionanocomposite films reinforced with different loads of cellulose nanofibrils obtained from açaí ( Euterpe oleraceae Mart.) under two nanofibrillation degrees. Nanofibrils were obtained by 3 and 21 passages in a grinder defibrillator. The films were produced by casting with nanofibril reinforcement at 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%. The increase in the nanofibril level and nanofibrillation degree reduced water vapor absorption (75.20% to 51.93%), water solubility (28.33% to 17.91%), and density (0.87 g.cm−3 to 0.61 g.cm−3). The water vapor permeability decreased with higher nanofibril loads for both 3-pass (47.30% to 43.61%) and 21-pass (49.82% to 44.48%) reinforced films, but not with nanofibrillation degree. The increase in 3-pass nanofibril level decreased tensile strength (8.18 MPa to 7.88 MPa), modulus of elasticity (867.62 MPa to 670.02 MPa) and elongation at break (0.02 mm.mm−1 to 0.01 mm.mm−1). However, the opposite effect happened to 21-pass nanofibrils, with increases from 9.16 MPa to 9.73 MPa and from 502.00 MPa to 1119.62 MPa for tensile strength and modulus of elasticity, respectively. Meanwhile, the maximum elongation at rupture did not vary. It was concluded that chitosan-based bionanocomposite films reinforced with 20 wt.% of 21-pass nanofibril were more resistant, except for water vapor permeability. Adding coarser nanofibrils enhanced this property. The 3-pass nanofibrils reinforcement enables water solubility, which benefits other packaging applications.

Vanillin based polymers: V. Poly(hydrovanilloin–urethane)

Renewable resources based hydrovanilloin [1,2- bis(4-hydroxy-3-methoxyphenyl)-1,2-ethanediol] was synthesized in 86% yield by electrochemical dimerization of vanillin in aqueous NaOH. This symmetrical bis-phenol monomer was then used for the preparation of urethane polymers by two different methods. In the first method a 1:2 mole ratio mixture of hydrovanilloin and diisocyanate was polymerized in DMF using 1,4-diazabicyclo[2,2,2]octane as the catalyst at 60°C, for 1 h to give poly(hydrovanilloin–urethane)s. In the second method diisocyanates were first reacted with polyethylene glycol-400 to give pre-polymers. Then prepolymers were reacted with equivalent amount of hydrovanilloin at 60°C for 4 days to produce poly(hydrovanilloin-ethylene glycol-urethane)s. The first method resulted hard poly(hydrovanilloin–urethane)s showing Tg values in the range of 121–172°C. The second method yielded softer poly(hydrovanilloin-ethylene glycol-urethane)s and these polymers failed to show distinct glass transition temperatures in the DSC analysis. However, poly(hydrovanilloin-ethylene glycol-urethane)s showed better thermal stabilities than polymers without polyethylene glycol units.

Perspectives of polylactic acid from structure to applications

The demand for an adoption of renewable resources rather than finitely available non renewable sources for industrial purposes are rising, with the growing environmental constraints. Polymers being one of the crucial part of almost all the industries, pioneer in the list of sources needed for various applications. This makes polymers that can be obtained from renewable sources being studied widely and are anticipated to make a revolution in the field of packaging industry, medical field, and automobile industry. Polylactic acid (PLA) is one among such biopolymers, which is an aliphatic polyester derived from lactic acid (2-hydroxypropionic acid), that find wide applications in food packaging industry, tissue scaffolding, and biomedical devices. This paper focuses on an in-depth review on polylactic acid, its structure, and various properties of PLA. The details of different polymer blends/composites based on PLA are also discussed here. The fields of applications, where PLA is being utilized and the future scopes of the polymer are also studied.

Preparation physical, mechanical properties and biodegradable study of SAN/EOC/nanoclay/proteins nanocomposite

In this paper, the mechanical and morphological properties of biodegradable SAN/EOC/Nanoclay/Proteins nanocomposite were investigated. The composites were first prepared by a laboratory-scale twin screw extruder. Morphology of the blend was determined by SEM images. Mechanical properties in terms of tensile tests were carried out by Testometric TS2000, stress at break, strain at break, and Young’s modulus was determined. Based on mechanical results, although the young’s modulus increases with increasing protein content but the strain at break of the composite decreases acutely because of the presence of protein. The blend indicated an improvement in mechanical and thermal properties. Today, according to the vast application of plastic in different fields, environmental issues were affected by these kinds of non-degradable materials, so that biodegradability of the plastics is just the remaining route to solve. In this research, biodegradable blends were prepared using whey protein as a biodegradable natural polymer. The results of the biological procedure-test after 3 months indicated sufficient weight loss and biodegradation of these blends.

Impact study of new formulations based on plasticized polyvinyl chloride (PVC)

The aim of this paper is the determination of the migration and biodegradation of the PVC additives in the soil. Epoxidized Sunflower Oil (ESO) was used as a thermal organic co-stabilizer for PVC; it was obtained by epoxidation of commercial sunflower oil. Two plasticizers were used: dioctyl phthalate (DOP) and diisononyl adipate (DINA). A natural aging test on site in a garden soil (Tizi Ouzou, Algeria) of the PVC samples was investigated for 6 months. The samples were characterized by Fourier transform infrared (FTIR).The morphological changes were followed by scanning electron microscopy (SEM). The evolution of the bacterial growth, identification using biochemical tests, variation of pH and variation of mass were investigated. The results showed that the nature of the plasticizer and heat stabilizer affects the properties of PVC as well as the phenomena of migration and biodegradation.

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

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 temperatures. Results of rheological characteristics in a steady shear rate showed pseudoplastic properties and the dynamic rheological properties showed a fluid-like viscoelastic behavior. The flow and viscoelastic characteristics of polysaccharides were described using the power-law (the Ostwald model). The values of flow behavior index of the sample were close to unity (0.91) for 3% and it decreased up to 0.71 for 9% revealing the shear-thinning (pseudoplastic) nature of these polysaccharides. Moreover, the consistency coefficient increased non-linearly with concentration and it was described by a power law. The flow behavior as a function of temperature was satisfactorily described using the Arrhenius law and the activation energy values were extracted. It decreased from 15.68 and 17.21 kJ/mol when the concentration increased from 5 to 9% (w/v). Additionally, in dynamic rheological measurements, tan δ > 1 and G″ > G′ reveling a shear-thinning behavior. Finally, the analysis of the FTIR spectra of these polysaccharides showed the presence of uronic acid groups. This behavior would suggest that polysaccharides extracted from Cystoseira myriophylloides could be an interesting additive as thickeners.

Synthesis of highly stable κ/ι-hybrid carrageenan micro- and nanogels via a sonication-assisted microemulsion route

Novel carrageenan micro- and nanogels were developed via a sonication-assisted microemulsion processing route. The diameter of the dry samples ranged 197.3 −421.35 nm whereas the diameter of the samples suspended in water ranged 467.8–605.9 nm. Hybrid κ/ι-carrageenan, rather than κ- or ι-carrageenan was used for the first time for the preparation of micro- and nanogels. KCl was used as a cross-linking agent and Tween 80 was used as surfactant. The micro- and nanogels suspended in water were found to simultaneously exhibit a lower diameter, and a lower swelling ratio with higher Tween 80 content. The micro- and nanogel suspension yields a zeta potential value of −50.5 mV, superior to values reported elsewhere for pure κ- or ι-carrageenan micro- and nanogels. The high stability was attributed to the high hydrophile-lipophile balance (HLB = 15) value of Tween 80. These results suggest that hybrid κ/ι-carrageenan micro- and nanogels are promising candidates for smart therapeutics applications.

Effects of kenaf filler reinforcement on mechanical properties of molded polypropylene composites: A particle size study

The combination of natural fibers in petroleum plastic soften industrial footprints on the environment. Plastic matrix can be filled with renewable resources leading to a greener composite that is biodegradable. This paper focuses on particulate kenaf filler modification and its affects on the properties of polypropylene, processing techniques and the use of particle size filler for improving linkages between fiber and polymeric matrixes.