Starch-based Biodegradable Polymers Research Articles

Modeling of degradation ability for starch-based biodegradable polymer film using ANFIS

Modeling of degradation ability for starch-based biodegradable polymer film using ANFIS

Sugar palm (Arenga p innata) thermoplastic starch nanocomposite films reinforced with nanocellulose

Abstract The growing consciousness about global environmental concerns, particularly landfills, in conjunction with the rapid use of petroleum-based plastics, is a key factor behind the use of natural and biodegradable polymers in short-life applications like food packaging, container, and tray. Sugar palm stem is a biomass that has proven the potential to produce biodegradable polymers such as sugar palm starch. Nevertheless, their applications were limited due to their low tensile strength and excessive hydrophilicity. Plasticization using polyols, reinforcement with sugar palm fiber, cellulose, microcrystalline cellulose, or nanocellulose, blending with thermoplastic polymer, and addition of essential oils has been used to maximize the functional qualities of the starch biopolymer. As the content of plasticizers grew, the glass transition temperature and water absorption ability decreased. Furthermore, the addition of sugar palm nanocellulose to sugar palm starch improves the performances of sugar palm starch-based films as a packaging material. Addition of essential oil contributes to antibacterial properties and slightly improved tensile strength of the film. A comprehensive understanding on the interaction of starch-based biodegradable polymer and nanocellulose constituents for enhancing the physico-chemical properties of starch-based films is prerequisite for researchers in the design of industrial products with enhanced functional attributes. To address the knowledge gap, more studies including the reinforcement of new types of biodegradable polymer and nanocellulose derived from natural sources should be conducted in order to continually populate the database for research purposes.

Green Composites Based on Mater-Bi® and Solanum lycopersicum Plant Waste for 3D Printing Applications

3D printability of green composites is currently experiencing a boost in importance and interest, envisaging a way to valorise agricultural waste, in order to obtain affordable fillers for the preparation of biodegradable polymer-based composites with reduced cost and environmental impact, without undermining processability and mechanical performance. In this work, an innovative green composite was prepared by combining a starch-based biodegradable polymer (Mater-Bi®, MB) and a filler obtained from the lignocellulosic waste coming from Solanum lycopersicum (i.e., tomato plant) harvesting. Different processing parameters and different filler amounts were investigated, and the obtained samples were subjected to rheological, morphological, and mechanical characterizations. Regarding the adopted filler amounts, processability was found to be good, with adequate dispersion of the filler in the matrix. Mechanical performance was satisfactory, and it was found that this is significantly affected by specific process parameters such as the raster angle. The mechanical properties were compared to those predictable from the Halpin-Tsai model, finding that the prepared systems exceed the expected values.

Synthesis and validation of water-soluble cationic biodegradable starch as a flocculant

All efforts must be made to preserve water's purity for the present and the future because it is necessary for environment's sustenance and for all living things including humans, vegetation and animals. This project is an experiment to synthesize a flocculant for industrial effluent and as a result grafted starch-based biodegradable polymer is created to benefit both natural and synthetic polymers. This research focused on creating water-soluble, cationic, biodegradable starch to use as a flocculant. The reactive groups of the starch, or hydroxyls, combine with the cations in the reagent to produce a complex. The complex can separate creating free radical sites on the polysaccharide backbone. The mechanism of free radical graft copolymerization of ethyl monomers onto starch is anticipated in the presence of molecular nitrogen. H+ may be replaced by Reactive group R i.e. (CH2 CH3)3 N - (Et3)N in highly Alkaline medium. The effect of flocculant is validated on industrial effluent by jar test with various coagulation treatments.

Hedysarum coronarium-Based Green Composites Prepared by Compression Molding and Fused Deposition Modeling

In this work, an innovative green composite was produced by adding Hedysarum coronarium (HC) flour to a starch-based biodegradable polymer (Mater-Bi®, MB). The flour was obtained by grinding together stems, leaves and flowers and subsequently sieving it, selecting a fraction from 75 μm to 300 μm. Four formulations have been produced by compression molding (CM) and fused deposition modeling (FDM) by adding 5%, 10%, 15% and 20% of HC to MB. The influence of filler content on the processability was tested, and rheological, morphological and mechanical properties of composites were also assessed. Through CM, it was possible to obtain easily homogeneous samples with all filler amounts. Concerning FDM, 5% and 10% HC-filled composites proved also easily printable. Mechanical results showed filler effectively acted as reinforcement: Young’s modulus and tensile strengths of the composites increased from 74.3 MPa to 236 MPa and from 18.6 MPa to 33.4 MPa, respectively, when 20% of HC was added to the pure matrix. FDM samples, moreover, showed higher mechanical properties if compared with CM ones due to rectilinear infill and fibers orientation. In fact, regarding the 10% HC composites, Young’s modulus of the CM and FDM ones displayed a relative increment of 176% and 224%, respectively.

Influence of Almond Shell Content and Particle Size on Mechanical Properties of Starch-Based Biocomposites

This work reports on the effect of the particle size of almond shell powder (ASP) filler on starch-based biodegradable polymer. Different size ranges of particles were studied: < 0.05 mm, 0.05–0.08 mm, 0.08–0.125 mm and 0.125–0.250 mm in biocomposites with 30 wt% ASP. Additionally, biocomposites with 5 wt%, 10 wt% and 20 wt% of filler were prepared with ASP of 0.08–0.125 mm particle size. Biocomposites were manufactured by extrusion-compounding, and test samples were produced by injection moulding with the aim to study mechanical and thermal properties. The possibility of implementing the developed biocomposites in traditional industries, such as toys or packaging was evaluated, as biodegradable materials have gained great industrial interest in recent years owing to the coming legislative requirements and/or due to customer demands. The addition of the ASP on the polymeric matrix increases the stiffness of the polymer and reduces the deformation at break, the impact strength and the thermal stability. On the other hand, the final natural aesthetics provided by the filler is highly appreciated by the manufacturers and consumers (Blasco in Consumer attitudes and toy trends for eco-babies and bio-parenting, Nuremberg, 2020; Baeza in Childcare trends 43–45, 2020). The results of the study showed that, the filler content had a more significant effect than the particle size on the mechanical properties of the biocomposites.

Fabrication and Characterization of Starch-Based Biodegradable Polymer with Polyvinyl Alcohol

Starch is a renewable, biodegradable and low-cost natural biopolymer with high availability. Starch was extracted from Solanum tuberosum (potatoes) and its preliminary properties were studied. The structure of extracted starch was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). A series of starch-based biodegradable blends, with polyvinyl alcohol (PVA) were prepared by using glycerol as a plasticizer and citric acid as a cross-linking agent, through solution casting method and their biodegradable properties were studied. The structure of the blend was characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC). The morphology of starch shows the potato starch has oval or ellipsoid in the structure having a size of 20-35 µm. The compatibility of the two components can be improved by the hydroxyl group present on both starch and PVA. As compared to pure polyvinyl, the melting point of the blend was decreased. The blends were found degradable within a weak.

Multiple Reprocessing Cycles of Corn Starch-Based Biocomposites Reinforced with Curauá Fiber

Biocomposites with a corn starch-based biodegradable polymer as matrix and 10 wt% vegetable curaua fiber were processed by injection molding and were submitted to reprocessing up to ten cycles with or without 3 wt% of maleic anhydride grafted polypropylene as coupling agent. The effect of reprocessing on hardness, impact and tensile properties as well as on the morphology, thermal properties, chemical structure and soil degradation behaviour of the matrix and biocomposites was evaluated. Curaua fibers have increased hardness, impact and tensile strengths as well as increased tensile modulus and decreased elongation at break of the biocomposites with respect to starch-based matrix and these properties slightly decreased or no considerable changes were observed with the reprocessing cycle increase. The addition of coupling agent promoted an increase in all properties and they remained almost constant with the reprocessing cycle increase. Thus, the incorporation of curaua fiber within starch-based matrix can improve the mechanical properties of the biocomposites which showed potential to be recycled despite the weight loss in soil degradation tests reached around 10 wt% after 230 days for biocomposites reprocessed ten cycles.

Full-scale performance of selected starch-based biodegradable polymers in sludge dewatering and recommendation for applications.

Agricultural reuse of dewatered sludge is a valid route for sludge valorization for small and mid-size wastewater treatment plants (WWTPs) due to the direct utilization of nutrients. A more stringent of German fertilizer ordinance requires the degradation of 20% of the synthetic additives like polymeric substance within two years, which came into force on 1 January 2017. This study assessed the use of starch-based polymers for full-scale dewatering of municipal sewage sludge. The laboratory-scale and pilot-scale trials paved the way for full-scale trials at three WWTPs in Germany. The general feasibility of applying starch-based 'green' polymers in full-scale centrifugation was demonstrated. Depending on the sludge type and the process used, the substitution potential was up to 70%. Substitution of 20-30% of the polyacrylamide (PAM)-based polymer was shown to achieve similar total solids (TS) of the dewatered sludge. Optimization of operational parameters as well as machinery set up in WWTPs is recommended in order to improve the shear stability force of sludge flocs and to achieve higher substitution potential. This study suggests that starch-based biodegradable polymers have great potential as alternatives to synthetic polymers in sludge dewatering.

Comparison between biodegradable polymers from cassava starch and glycerol as additives to biogas production

In this study, we compared cassava starch-based biodegradable polymers (PBMs) and glycerol (G) as additives used to increase biogas production from the co-digestion of swine wastewater (ARS). We chose to work with an inoculum comprising 40% (v/v) of the total volume of the reactor; this inoculum was obtained from a Canadian model digester for treating swine waste. In the anaerobic digestion process, batch reactors were used on a laboratory scale with a total volume of approximately 4 L and a working volume of 3.2 L. Three treatments were conducted to compare the efficiency of solid removal, the chemical oxygen demand (COD), and the production of biogas. The first treatment contained only swine waste; the second included the addition of glycerol at 1, 3, and 5% (w/v); and the third treatment included the addition of 1, 3, and 5% (w/v) of PBM residue in relation to the swine wastewater. From the results, it can be concluded that higher yields were obtained for the treatment with 3% PBM and 1% glycerol. Most treatments showed high removal rates of total solids and total volatile solids. Reductions lower than 70% were obtained only for treatments with PBM and glycerol at a ratio of 5%.

Thermal Properties and Cellular Structure of Cornstarch-Based Foams Formed by Extrusion Technology

The aim of this work was to investigate the edible corn grit/PVOH (polyvinyl alcohol) blends of their thermal properties by using differential scanning calorimetry (DSC) and thermogravimetric analysis, and the average pore sizes and cellular structures of the blend foams were also characterized by using scanning electron microscopy. The thermal decomposition of edible corn grit/PVOH blends shifted slightly toward lower temperature compared to PVOH. This result shows that edible corn grit/PVOH blends suppress the thermal stability of PVOH. DSC result shows that PVOH and edible corn grits were miscible. Furthermore, the cell sizes become smaller and more uniform and the cell walls become thinner with the increase in PVOH ratio. Moreover, using the CaCO3 also made the cell sizes become smaller and more uniform. Corn-based foams have practical mechanical properties, but they are difficult to mold into shaped products. They will have a greater commercial potential if the extrusion process were more amenable to making molded foam articles, such as food and beverage containers, and if it were compatible with fiber or other reinforcing materials. Practical Applications In this study, edible corn grit/PVOH blends were prepared by using extrusion technology and the CaCO3 as the thermal conductor. Corn grit is renewable from carbon dioxide, water and sunshine. It is biodegradable, cheap and easily modified physically or chemically. This means someday it is unnecessary to rely on petroleum to prepare polymers; people may “plant” polymers of suitable performances from the earth, and the environmental problems will no longer be as severe as today. At present and in the near future, different physical and chemical approaches are effective strategies to develop completely starch-based biodegradable polymers of appropriate biocompatibility, degradation rate and physical properties for various applications.

Natural compounds as light stabilizer for a starch-based biodegradable polymer

Abstract The photooxidation behavior of a commercial starch-based biodegradable polymer, i.e., new generation Mater-Bi, loaded with natural stabilizers was investigated in consideration for outdoor agricultural applications. The photooxidation behavior of the biodegradable films was monitored mainly by mechanical tests and spectroscopic analysis. In order to formulate biodegradable films without any synthetic compounds, suitable for outdoor applications and with good photooxidation stability, antioxidants such as α-tocopherol and quercetin (Q) were considered. The results obtained using natural compounds were compared with those obtained by using a synthetic antioxidant and a light stabilizer. Among the investigated natural compounds, the flavonoid compound seemed to work better than the antioxidant and the improvement in the photooxidation behavior of the biodegradable film was very similar to that obtained using the synthetic light stabilizer. A flavonoid compound can be considered as an outstanding natural stabilizer to replace synthetic light stabilizers in the formulation of 100% natural compounds based films, suitable for outdoor applications.

Biodegradable coordination polymer: Polycondensation of glutaraldehyde and starch in complex formation with transition metals Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)

Starch a biopolymer, possesses many unique characteristics features accompanied with some shortcoming simultaneously. Some synthetic compounds are of great help to these demerits of starch and so by an addition of all these alternatively may acquire the tailor made features of starch-based compounds. By combining the individual advantages of starch and some other compounds and elements, starch-based biodegradable polymers were prepared for potential applications in biomedical and environmental fields. In this research, the structural analysis and characterization studies of starch glutaraldehyde polycondensed polymer were undertaken, and then the formation of polymer metal complexes with transition metal in coordinated form are carried out. FT-IR spectroscopy and 1H NMR and 13C NMR spectroscopy were used to analyze the functionality of the synthesized compound. CHN of the synthesized compound was supported by FT-IR and NMR which again proved helpful for structural analysis. Electronic spectroscopy confirmed the geometry of the synthesized compounds. Thermal studies were carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Besides this the biodegradable studies were carried out by ASTM standards of biodegradable materials by CO2 evolution in respirometric titration method. All the polymers showed good thermal strength and reduced biodegradation on attachment of transition metals, Mn(II), Co(II), Ni(II), Cu(II) and Zn(II).

Thermoplastic starch composites reinforced by agricultural by-products: properties, biodegradability, and application

This article focuses on the development of starch-based biodegradable polymer composites reinforced by agricultural by-products. Maize hull and sugarcane bagasse were used as reinforcements in maiz...

Alkaline treatments to render starch-based biodegradable polymers self-mineralizable

The present research aims to develop a new route for surface functionalization of biodegradable polymers. The method is based on a wet chemistry modification, resulting in etching and/or hydrolysis in order to increase the amount of polar groups, such as hydroxyl (--OH) and carboxylic (--COOH) groups on the surface of the polymer. The polymer used as substrate was a corn starch-ethylene vinyl alcohol biodegradable blend (SEVA-C). For that purpose it was used in two different types of activation: (a) calcium hydroxide solution [Ca(OH)(2)] and (b) sodium hydroxide solution (NaOH). These treatments lead to the formation carboxylic acid-rich SEVA-C surfaces. Then, the samples were soaked in simulated body fluid (SBF) for different time periods of time until 7 days. After 1 day in SBF, the surface of SEVA-C was fully covered with spherulite particles. As the soaking time increased, the particles increased and coalesced, leading to the formation of a dense and uniform layer. Furthermore, thin-film X-ray diffraction confirms that the layer formed on the surface of the polymer was an apatite-like layer. These results suggest that this rather simple treatment is a good method for surface functionalization and subsequent mineral nucleation and growth on biodegradable polymeric surfaces to be used for bone-related applications.

Durability of a starch-based biodegradable polymer

The photo-oxidation and the photo-stabilization of a commercial biodegradable polymer have been investigated in order to establish the possibility of using this polymer as raw material for films for agriculture. The degradation has been followed by measuring the mechanical properties as a function of photo-oxidation time and in particular by following the elongation at break. The virgin polymer, made from maize starch and a synthetic biodegradable polyester, shows poor resistance to the UV irradiation as observed by the fast decay of the elongation at break, but the presence of small amounts of conventional UV stabilizers strongly improves the durability of this polymer. The UV stabilizers remarkably extend the induction time without modifying the photo-oxidation kinetics. Among the investigated stabilizers, the benzophenone compound seems to work slightly better than the benzotriazoles, than the triazine and than the sterically hindered amine. This behaviour has been attributed to the larger absorbance in the UV range of the biodegradable polymer.

The effect of starch-based biomaterials on leukocyte adhesion and activation in vitro

Leukocyte adhesion to biomaterials has long been recognised as a key element to determine their inflammatory potential. Results regarding leukocyte adhesion and activation are contradictory in some aspects of the material's effect in determining these events. It is clear that together with the wettability or hydrophilicity/hydrophobicity, the roughness of a substrate has a major effect on leukocyte adhesion. Both the chemical and physical properties of a material influence the adsorbed proteins layer which in turn determines the adhesion of cells. In this work polymorphonuclear (PMN) cells and a mixed population of monocytes/macrophages and lymphocytes (mononuclear cells) were cultured separately with a range of starch-based materials and composites with hydroxyapatite (HA). A combination of both reflected light microscopy and scanning electron microscopy (SEM) was used in order to study the leukocyte morphology. The quantification of the enzyme lactate dehydrogenase (LDH) was used to determine the number of viable cells adhered to the polymers. Cell adhesion and activation was characterised by immunocytochemistry based on the expression of several adhesion molecules, crucial in the progress of an inflammatory response. This work supports previous in vitro studies with PMN and monocytes/macrophages, which demonstrated that there are several properties of the materials that can influence and determine their biological response. From our study, monocytes/macrophages and lymphocytes adhere in similar amounts to more hydrophobic (SPCL) and to moderately hydrophilic (SEVA-C) surfaces and do not preferentially adhere to rougher substrates (SCA). Contrarily, more hydrophilic surfaces (SCA) induced higher PMN adhesion and lower activation. In addition, the hydroxyapatite reinforcement induces changes in cell behaviour for some materials but not for others. The observed response to starch-based biodegradable polymers was not significantly different from the control materials. Thus, the results reported herein indicate the low potential of the starch-based biodegradable polymers to induce inflammation especially the HA reinforced composite materials.

Study of the influence of β‐radiation on the properties and mineralization of different starch‐based biomaterials

In this work, the effects of beta-radiation are assessed, for the first time, on starch-based biodegradable polymers, with the aim of using it as an alternative sterilization process to the previously studied sterilization methods. Different doses of radiation were used in order to investigate the possibility of using this sterilization technique as a treatment to tailor the surface and bulk properties (namely mechanical) of these polymers. The as-treated substrates were characterized by water-uptake measurements and contact angle (theta) measurements. The mechanical properties of the materials were characterized by tensile tests by means of ultimate tensile strength (UTS) and strain at break (epsilon). The fracture of the surfaces was observed by scanning electron microscopy (SEM). Dynamic mechanical analysis (DMA) was also used to characterize the viscolelastic behavior of the irradiated materials. The main effect of sterilization with beta-radiation over the starch-based polymers seems to be a surface modification by an increase of the hydrophilicity. Nevertheless, because beta-radiation did not significantly affect the mechanical properties, it can be regarded as an effective way of modifying the surface for applications were more hydrophilic surfaces are desirable.

Sodium silicate gel as a precursor for the in vitro nucleation and growth of a bone-like apatite coating in compact and porous polymeric structures

In the present work, a new methodology to produce bioactive coatings on the surface of starch-based biodegradable polymers or other polymeric biomaterials is proposed. A sodium silicate gel is employed as an alternative nucleating agent to the more typical bioactive glasses for inducing the formation of a calcium-phosphate (Ca-P) layer. The method has the advantage of being able to coat efficiently both compact materials and porous 3D architectures aimed at being used on tissue replacement applications and as tissue engineering scaffolds. By means of this treatment, it is possible to observe the formation of an apatite-like layer, only after 6 hours of simulated body fluid immersion. For the porous materials, this layer could also be observed inside the pores, clearly covering the cell walls. Furthermore, an increase of the surface hydrophilicity (higher amount of polar groups in the surface) might contribute to the formation of silanol groups that also act as apatite inductors. After 30 days of SBF immersion, the apatite-like films exhibit a partially amorphous nature and the Ca/P ratios became much closer to the value attributed to hydroxyapatite (1.67). The obtained results are very promising for the development of cancellous bone replacement materials and for pre-calcifying bone tissue engineering scaffolds.

Evaluation of the potential of starch-based biodegradable polymers in the activation of human inflammatory cells.

The inflammatory response resulting from the implantation of a medical device may compromise its performance and efficiency leading, in certain cases, to the failure of the implant. Thus, the assessment of the behavior of inflammatory cells in vitro, constitutes a key feature in the evaluation of the adverse potential, or not, of new promising biomaterials. The objectives of this study were to determine whether starch-based polymers and composites activated human neutrophils. Blends of starch with ethylene-vinyl alcohol, with cellulose acetate and polycaprolactone, as well as composites based on all these materials filled with hydroxyapatite have been studied. A lysozyme assay was adapted to examine enzyme secretion from human neutrophils incubated with different starch-based materials. Changes in the free radical and degranulation activity of the neutrophil were also determined by measuring the luminescent response of Pholasin, a photoprotein that emits light after excitation by reactive oxygen species. The amount of lysozyme secreted by neutrophils incubated with the polymers did not exhibit significant differences between the tested materials. Results were in all cases similar to those obtained for the control (polypropylene) except for one of the starch blends (corn starch with polycaprolactone reinforced with 30% (w/w) of HA). The chemiluminescence experiments showed that polymers reduce the signal produced by activated neutrophils. Furthermore, for some polymers it was demonstrated that the phenomenon was due to an effect of the surface of the materials in cell adhesion or a simultaneous competition for the photoprotein in solution, which results in the decrease of the intensity of light emitted and detected.