Thermoplastic Corn Starch Research Articles

Jute fibre reinforced biodegradable composites using starch as a biological macromolecule: Fabrication and performance evaluation

The aim of this study is to develop environment friendly packaging and life style materials for replacing conventionally explored hazardous synthetic materials. The study carried out by using raw jute fibre reinforced thermoplastic corn starch (TPCS) is to develop biodegradable flexible composite materials. Flexible composites are prepared by maintaining with different fibre content (30 %, 40 % and 50 wt%). A thin coating of polyurethane based formulation is applied on one side of the developed composite to make it water resistant. Composite samples are examined in terms of their tensile properties, tear resistance, folding endurance, water absorbency, capillary action etc. The results show that flexible composites, having 50 % fibre content have tensile strength of 12.8 MPa and 12 MPa at cross and machine direction respectively compared to 3.1 MPa for the TPCS film. The Water drop test on the coated side of the developed material concluded that there is no water penetration even after 60 min of wetting. The interaction between two hydrophilic components is established with FTIR analysis. The XRD analysis was carried out to find the crystallinity of TPCS, Jute fibre and composite samples. Surface morphology and fibre/matrix interaction is observed by SEM. The detail chemical mechanism involved of fibre matrix interaction also been postulated. The scientific finding shows that the developed flexible material can be suitable for making packaging and life style items.

Development of Bilayer Polysaccharide-Based Films Combining Extrusion and Electrospinning for Active Food Packaging

The development of active food packaging is desirable for food safety and to avoid food loss and waste. In this work, we developed antioxidant bilayer films combining extrusion and electrospinning techniques. These films consisted of a first layer of thermoplastic cornstarch (TPS), incorporated with microcrystalline cellulose (MCC). The second layer consisted of gallic acid (GA) encapsulated at different concentrations in 1:1 chitosan/poly(ethylene-co-vinyl alcohol) (CS/EVOH) nanofibers. This layer was directly electrospun onto the TPS/MCC film. The morphological, structural, wettability, permeability to oxygen, and antioxidant properties were investigated for the first layer and the bilayer films. Water contact angle measurements revealed the hydrophobic nature of the first layer (θ0 = 100.6°). The oxygen permeability (OP) was accessed through the peroxide value (PV) of canola oil, kept in containers covered by the films. PV varied from 66.6 meq/kg for the TPS/MCC layer to 60.5 meq/kg for a bilayer film. Intermolecular hydrogen bonds, mediated by GA, contributed slightly to improving the mechanical strength of the bilayer films. The bilayer film incorporated with GA at 15.0% reached a radical scavenging activity against the DPPH radical of (903.8 ± 62.2) μmol.L−1.Eq. Trolox.g−1. This result proved the effectiveness of the GA nanoencapsulation strategy.

Extraction and characterization of cellulose microfibers from cornhusk for application as reinforcing agent in biocomposite

This study aims to extract and characterize cellulose microfibers from cornhusk, an agricultural by-product. The extracted fibers will then be used as a reinforcing agent in a biocomposite made of thermoplastic corn starch. The process of extracting cellulose microfibers involved two treatments: sequential alkali treatment (using sodium hydroxide at 120 °C for 120 min) and peroxide bleach treatment (using hydrogen peroxide at 90 °C for 60 min). Various techniques such as Fourier transform infrared (FTIR), X-Ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were employed to characterize the extracted fibers. The properties of the composite were examined through tensile strength tests, contact angle measurements, and UV–Vis spectrophotometry. The study found that cellulose microfibers were successfully extracted from cornhusks, with a diameter of 7 to 30 μm and a crystallinity of 65 %. The treated fibers showed gradual degradation between 150 °C and 350 °C, indicating a lower amount of non-cellulosic substances compared to untreated cornhusks. Adding 10 % of the microfibers to the thermoplastic starch composite increased the tensile stress at breaking and the Young's modulus, but decreased the contact angle of water droplets and the film's transparency.

Influence of Glycerol and SISAL Microfiber Contents on the Thermal and Tensile Properties of Thermoplastic Starch Composites.

The increasing use of petroleum plastics has caused environmental damage due to the degradation time of these materials. An alternative to petroleum plastics could be thermoplastic starch (TPS). However, thermoplastic starch does not exhibit satisfactory tensile properties. The mechanical properties of thermoplastic starch can be improved by adding sisal microfibers. Thus, the objective of this study was to evaluate the influence of different levels of glycerol and sisal microfibers on the thermal and tensile properties of thermoplastic corn starch composites. The microfibers were obtained via mechanical treatment followed by chemical treatment (alkaline treatment and bleaching). The films were obtained by the casting method using commercial corn starch and glycerol as a plasticizing agent, reinforced with sisal microfibers. Fourier transform infrared spectroscopy (FTIR) results revealed that the addition of microfibers did not change the chemical structure of the TPS matrix. The films from the samples with 18% glycerol and 10% microfibers had the highest value for the maximum tension, equal to 4.78 MPa. The thermal decomposition profile of TPS was not altered by the addition of microfibers. Our findings demonstrated the profound influence of glycerol and microfiber contents on the tensile properties of thermoplastic starch composites.

Effect of a keratin coupling agent on the mechanical properties of a bovine hair-thermoplastic starch composite

A coupling agent (CA) was obtained through chemical modification of bovine hair. For that purpose, hair waste was treated using two concentrations of potassium hydroxide (KOH), 0.15 and 0.25 N. Treated and untreated hair waste was characterized. Fourier-transform infrared (FTIR) spectra showed that alkali treatment caused the formation of thiols (773 cm−1) and sulfonate groups (1063 cm−1 and 1041 cm−1) as a consequence of disulfide bond breakage. Furthermore, the keratin structure was disorganized (1697 cm−1), and functional groups –NH2 (1574 cm−1) were exposed. The vibrational analysis confirmed S–S bond cleavage to form S–H groups. Thermogravimetric analysis indicated an important disorganization of the keratin molecule. Additionally, differential scanning calorimetry (DSC) analysis corroborated the protein denaturation due to decomposition of the α-helix. Scanning electron microscopy (SEM) showed a clear effect on hair surface integrity, which promotes its interaction with the polymer matrix. Water absorption assays showed that alkaline treatment produces higher absorption due to a greater presence of polar functional groups. With the aim of assessing the CA's ability to act as a compatibilizer in a composite material, it was mixed with thermoplastic cornstarch (TPS) as a polymeric matrix and untreated hair fiber (UHF) as a reinforcing agent. The composites were processed by extrusion and injection molding. Young's modulus, tensile strength, and elongation at break were evaluated, showing higher values for the first two when the percentage of CA was increased.

Thermoplastic starch hybrid biocomposite films with improved strength and flexibility produced through crosslinking via carboxylic acid

Thermoplastic starch (TPS) suffers from its intrinsic low mechanical strength and high brittleness due to its strong hydrogen bonding and low chain mobility. The conventional way to crosslink the TPS film can improve the strength and stiffness of the films, but usually reduces the flexibility of the film, and increases its brittleness. In this study, the incorporation of the hybrid nanofiller [1 wt% nanocellulose (C) and 4 wt% nano bentonite (B)] into the TPS proved to improve greatly the films’ strength and flexibility. The hybrid nanofillers with ratio 4B:1C was incorporated into the crosslinked thermoplastic corn starch (CR-TPCS) film to increase the its flexibility and toughness and produced a high mechanical strength fully biodegradable film. Two different aqueous carboxylic acids: citric acid (CA) and tartaric acid (TA) with different pH values (2,4,6) as the green crosslinker were employed. Substantial increase of tensile strength (3.98 to 9.17 MPa), Young’s modulus (9.10 to 46.30 MPa) and elongation at break (55.2 to 135.7%) was observed for the CA- 4B1C/pH2 films compared to the CR-TPCS films. The melting temperature (Tm) of the CA-4B1C/pH2 improved compared to the TPCS/4B1C (un-crosslinked) film due to its crosslinking effect. Meanwhile, the CA-4B1C films exhibited the highest degree of substitution and di-esterification with the lowest swelling and water solubility properties due to the formation of a special “bridge” structure between the CA, nanocellulose and plasticizer. The “bridge” structure developed between the TPCS chains serves as the toughener to motivate higher chain stress relaxation and load endurance. The crosslinked “bridge structure” also proved to effectively reduce the retrogradation phenomenal in the TPCS films. This combination method of hybridization and crosslinking is an efficient, low cost, and environmentally friendly technique to overcome the low flexibility and brittleness problem of the TPS based packaging film.

The role of natural hybrid nanobentonite/nanocellulose in enhancing the water resistance properties of the biodegradable thermoplastic starch

Abstract This study focuses on investigating the effect of hybrid nanofillers on the hydration characteristics and soil biodegradability of the thermoplastic corn starch (TPCS) hybrid nanofiller biocomposite (TPCS-HB) films. The data were benchmarked with that of the pure TPCS and TPCS single nanofiller biocomposite (TPCS-SB) as control films. The water absorption properties of TPCS, TPCS-SB, and TPCS-HB films were analyzed and fitted with the standard Guggenheim–Anderson–de Boer equation to study the water activity of the films. Besides, the water permeability test, water vapor permeability, and soil biodegradability of the films were also studied and correlated with the films’ surface morphology. The results indicated that the TPCS-HB films possess excellent hydration resistance and comparable biodegradable rate with the TPCS-SB films. The optimal water resistance properties were achieved when the optimal ratio of nanobentonite/nanocellulose (4:1) was incorporated into the TPCS matrix. The outcomes of this study provide an innovative idea and new insights that, by using natural and hybrid nanofillers, the hydrophobicity of the TPCS films could be enhanced. TPCS-HB films show great potential to be developed into a fully green biodegradable TPCS biocomposite film, especially for single-use plastic applications.

An experimental study on the microstructural, tensile, and fracture properties of biodegradable polylactic acid blended with thermoplastic corn starch filled with halloysite nanotubes

In this study, the tensile and fracture behavior of polylactic acid (PLA)/ thermoplastic corn starch (TPS) filled with halloysite nanotubes (HNTs) was investigated. Adding TPS noticeably decreased the tensile strength and modulus, but increased the elongation at break. Adding TPS to 60 wt% reduced the tensile strength and modulus by 61% and 92%, respectively, but increased the elongation at break by 77%. Adding HNTs in PLA/ TPS improved the tensile modulus, but diminished the elongation at break and tensile strength. Analysis of the fracture behavior was performed by the essential work of fracture (EWF) method. The results revealed that adding 20 wt% of TPS to PLA increased EWF and non-EWF by 298% and 109%, respectively. According to the desirability function, the best strength, stiffness, and toughness balance were obtained for the sample containing 20 wt% of TPS and 1 wt% of HNTs.

Physical Properties of Thermoplastic Cornstarch/Hibiscus sabdariffa Fiber Obtained by Evaporation Casting

AbstractHibiscus sabdariffa is a typical ingredient in a popular Mexican beverage, and a lot of waste is produced as a result. The fibers obtained from Hibiscus sabdariffa waste can be used as reinforcement in a natural composite. This research evaluates the influence and effect of different properties of fiber incorporated into a cornstarch matrix. The mechanical and thermomechanical performance is evaluated using tensile measurements and dynamic mechanical analysis. Thermal stability is analyzed by thermogravimetric analysis. The micrographics show a good incorporation of the bioreinforcement into the polymer matrix. The tensile measurements show that the fiber can be related to a slight decrease in Young´s modulus. The dynamic mechanical analysis results show that the composite with 4 wt% of reinforcement has a higher storage modulus (1139 MPa at 50 °C) than the starch matrix (854 MPa at −50 °C). According to the thermal stability of the composites is displaced to lower temperatures, which can suggest an effect of biodegradation acquired with the progressive addition of the biofibers. As a result, the composites obtained have been shown to be sustainable and friendly to the environment, and the films can offer an advantage for packaging‐type bags for foods.

Toughening mechanism of thermoplastic starch nano-biocomposite with the hybrid of nanocellulose/nanobentonite

High flexibility and toughness are key criteria for an effective bioplastic packaging film. However, in most studies, the flexibility of thermoplastic starch (TPS) films is always neglected when targeting their tensile strength improvement. Low film flexibility has limited the development of TPS films in replacing the petrochemical-based plastic packaging films. In this communication, we report a method to produce thermoplastic corn starch (TPCS) films with excellent mechanical strength, high flexibility and high toughness through the hybridization of two natural nanofillers: nanobentonite and nanocellulose. The synergistic effect of the hybrid nanofillers can be observed through the arrangement of alternating nacre structures where the nanobentonite silicate layers are responsible for mechanical strength, while the nanocellulose promotes free volume in the TPCS matrix and triggers high film elongation at break. Structural, morphological, and thermomechanical analysis were conducted, and the detailed strengthening mechanism of the TPCS hybrid nano-biocomposite films was revealed.

The relationship between molecular structure and film-forming properties of thermoplastic starches from different botanical sources

To illustrate the correlations between molecular structures and the film-forming properties of thermoplastic starch from various botanical sources, starches from cereal, tuber and legume were modified by thermoplastic extrusion and the corresponding thermoplastic starch films were prepared including thermoplastic corn starch (TCS), thermoplastic rice starch (TRS), thermoplastic sweet potato starch (TSPS), thermoplastic cassava starch (TCAS) and thermoplastic pea starch (TPES) films. TPES film displayed a higher tensile strength (6.28 MPa) and stronger water resistance, such as lower water solubility (15.70 %), water absorption (42.35 %), and water vapor permeability (0.285 g·mm·h−1·m−2·kPa−1) due to higher contents of amylose and B1 chains. TCAS showed a smoother and more amorphous film due to higher amylopectin content, resulting higher elongation at break and larger opacity. TCS film was the most transparent due to a compacter network and more ordered crystallinity structure, which was suit for the packaging of fresh vegetables and aquatic products, whereas TCAS film was the opaquest, which protected package foods from light such as meat products, etc. The outcome would provide an innovative theory to regulate accurately the functional properties of thermoplastic starch films for different food needs.

Evaluación del uso del pseudotallo de plátano con almidón de maíz termoplástico para la elaboración de platos biodegradables

This project evaluated the use of fiber residues from the banana pseudostem (Musa Paradisiaca L.) with thermoplastic corn starch (Zea Mays) in the production of biodegradable dishes for food use. The homogenized mixture was gelatinized at 60 °C and thermopressed at 150 °C for 20 min. The amounts of thermoplastic starch and polyvinyl alcohol were varied.  The raw material and the final product were characterized by physical-chemical, mechanical, and thermal analyses. The lignocellulosic fibers improved the tensile strength, modulus of elasticity, hardness, and viscoelasticity in the dish, also presented hydrophilic character. Degradation increased with the increase of thermoplastic starch. The unit cost per dozen plates was $ 1.63. It is concluded that the residues of fibers from the pseudostem of banana and thermoplastic starch turned out to be an alternative in the elaboration of biodegradable dishes.

Using rice straw fractions to develop reinforced, active PLA-starch bilayers for meat preservation

Bilayers from thermoplastic corn starch (TPS) and PLA were obtained, incorporating or not rice straw (RS) valorised fractions: active extract (es) into PLA and cellulose fibres (cf) into TPS films. The films were obtained by thermoprocessing while the bilayers were obtained by thermocompression of the different monolayers (TPS-PLA, TPScf-PLA, TPS-PLAes and TPScf-PLAes). TPS conferred oxygen barrier capacity to the laminates, which was improved by the cf incorporation. The extract slightly reduced the PLA resistance but improved their oxygen barrier capacity. The tensile and barrier properties of the bilayers revealed changes in the performance of each layer associated with the interlayer compound migration. The TPScf-PLAes bags exhibited noticeable antioxidant capacity when used in meat packaging and reduced microbial counts throughout cold storage. Therefore, these bilayers have considerable potential to extend the shelf-life of meat samples, preserving their quality and safety for longer, while using RS fractions permits its valorisation.

Effective Aging Inhibition of the Thermoplastic Corn Starch Films through the Use of Green Hybrid Filler

Recently, hybrid fillers have been widely used to improve the properties of biopolymers. The synergistic effects of the hybrid fillers can have a positive impact on biopolymers, including thermoplastic corn starch film (TPCS). In this communication, we highlight the effectiveness of hybrid fillers in inhibiting the aging process of TPCS. The TPCS, thermoplastic corn starch composite films (TPCS-C), and hybrid thermoplastic corn starch composite film (TPCS-HC) were stored for 3 months to study the effect of hybrid filler on the starch retrogradation. TPCS-C and TPCS-HC were prepared by casting method with 5 wt% of fillers: nanocellulose (NC) and bentonite (BT). The alteration of the mechanical properties, aging behavior, and crystalline structure of the films were analyzed through the tensile test, Fourier transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and water absorption analysis. The obtained data were correlated to each other to analyze the retrogradation of the TPCS, which is the main factor that contributes to the aging process of the biopolymer. Results signify that incorporating the hybrid filler (NC + BT) in the TPCS/4BT1NC films has effectively prevented retrogradation of the starch molecules after being stored for 3 months. On the contrary, the virgin TPCS film showed the highest degree of retrogradation resulting in a significant decrement in the film’s flexibility. These findings proved the capability of the green hybrid filler in inhibiting the aging of the TPCS.

Phase morphology and thermomechanical performance of thermoplastic corn starch/polystyrene blends

This study compared the preparation and characterization of polymer blends containing two types of polystyrene (high-impact polystyrene (HIPS) and general-purpose polystyrene (GPPS)) and thermoplastic corn starch (TPS) as a natural resource. Melt extrusion was used to create TPS/polystyrene blends. SEM, XRD, and DMTA analyses were used to determine the compatibility and mechanical properties of GPPS/TPS and HIPS/TPS blends. SEM analysis revealed that TPS particle size was significantly smaller in HIPS blends than in GPPS blends, owing to lower interfacial tension and better compatibility between HIPS and TPS. According to the DMTA results, the storage modulus of both blends increased significantly, particularly at high PS concentrations. All blends had two peaks on the loss factor curve, one for each phase's glass transition. The Tg of the PS-rich phase in blends was nearly equivalent to the Tg of pure PS. On the other hand, Tg of the TPS-rich phase was unexpectedly lower than that of pure TPS. By adding a low volume of polystyrene to TPS (approximately 20 wt%), the ultimate tensile strength of TPS was increased by more than 200%. At high polystyrene concentrations (approximately 80 wt%), the blend exhibited mechanical properties comparable to pure PS.

Developing thermoplastic corn starch composites filled with brewer's spent grain for applications in biodegradable films

AbstractDespite the growing interest in utilizing starch‐based biodegradable films, their low mechanical properties generally limit them from being widely used. On the other hand, brewer's spent grain (BSG) is an abundant by‐product that does not yet have high added‐value industrial use. This study proposes the development of starch‐based composites filled with BSG for applications in biodegradable films. Different contents (1–5 wt%) of BSG fibers of different sizes (35, 60, and 100 mesh) were used aiming to identify the film compositions with better mechanical and thermal properties. The composites were produced by casting and had their mechanical, morphological, and thermal properties evaluated. The composites with the most promising mechanical properties contained 2.5 wt% BSG with 35 mesh and 1 wt% BSG with 100 mesh. Lower amounts of smaller BSG fibers resulted in balanced mechanical properties because of their higher surface area‐to‐volume ratio and higher aspect ratio. Results revealed that incorporating BSG may slightly improve the tensile strength and thermal stability of pure TPS, thus acting as a promising active filler due to the compatibility with the polymer matrix and increased polymer crystallinity. The developed films contribute to the circular economy and might be a promising low‐cost option for application in conventional packages or mulch films.

Microstructural and Physical Properties of Thermoplastic Corn Starch/Polystyrene Blend Foams Affected by Different Contents and Combinations of Plasticizers

A comprehensive study was performed on thermoplastic corn starch (TPS)/polystyrene (PS) blend foam to optimize the formulation from the aspects of plasticizer content and the blend ratio. Plasticization of native starch was implemented with various contents of plasticizer [water (W) + glycerol (G)], 21, 23, 25 and 29%, and W/G ratio of 1/2, 2/3, 3/2 and 2/1 using melt extrusion process. The influence of plasticizer loading content and also its combination on the microstructural and physical properties of the blend foam were investigated. The morphological consideration was also carried out by scanning electron microscopy to evaluate the distribution and regularity of the foam cells. The results showed that water had a desirable effect on the cell parameters in W + G = 21 and 29%. In the following, full factorial method in Minitab software was used to optimize the formulation according to the properties. Moreover, the effect of PS content on the moisture absorption and cell structure of TPS/PS blend foam was evaluated. In addition, the blend ratio of 20/80 was obtained as an optimum ratio for the TPS/PS blend foam via evaluating the effect of different contents of PS on the moisture absorption amount and cell structure of the blend foam. The addition of 20% PS to TPS caused to 6 times higher expansion ratio than PS and 60% higher than TPS, while 50% lower moisture absorption than TPS. This combination can be a good alternative candidate for warm food packing applications.

Valorization of Rice Straw into Cellulose Microfibers for the Reinforcement of Thermoplastic Corn Starch Films

In the present study, agro-food waste derived rice straw (RS) was valorized into cellulose microfibers (CMFs) using a green process of combined ultrasound and heating treatments and were thereafter used to improve the physical properties of thermoplastic starch films (TPS). Mechanical defibrillation of the fibers gave rise to CMFs with cumulative frequencies of length and diameters below 200 and 5–15 µm, respectively. The resultant CMFs were successfully incorporated at, 1, 3, and 5 wt% into TPS by melt mixing and also starch was subjected to dry heating (DH) modification to yield TPS modified by dry heating (TPSDH). The resultant materials were finally shaped into films by thermo-compression and characterized. It was observed that both DH modification and fiber incorporation at 3 and 5 wt% loadings interfered with the starch gelatinization, leading to non-gelatinized starch granules in the biopolymer matrix. Thermo-compressed films prepared with both types of starches and reinforced with 3 wt% CMFs were more rigid (percentage increases of ~215% for TPS and ~207% for the TPSDH), more resistant to break (~100% for TPS and ~60% for TPSDH), but also less extensible (~53% for TPS and ~78% for TPSDH). The incorporation of CMFs into the TPS matrix at the highest contents also promoted a decrease in water vapor (~15%) and oxygen permeabilities (~30%). Finally, all the TPS composite films showed low changes in terms of optical properties and equilibrium moisture, being less soluble in water than the TPSDH films.

Effect of the Biodegradable Compounds Composition with Monoglycerides on Mechanical Properties

The purpose of this work is to improve the production technology of biodegradable hybrid compositions based on low-density polyethylene with thermoplastic starch and new plasticizer–distilled monoglyceride and determination of the composition effect on mechanical properties. Starch was plasticized with a mixture of glycerol and distilled monoglycerides, instead of the known sorbitol. This article describes methods for producing biodegradable hybrid composite films based on polyethylene and thermoplastic starches (corn, pea and rice) with a mass ratio of components, respectively, 40:60÷60:40 and their mechanical properties. Properties and structure of composite films are studied using test methods, rheological parameters, optical microscopy, and differential scanning calorimetry. The advantages of using monoglycerides as a plasticizer in thermoplastic starch/ polyethylene compositions have been demonstrated. Composites obtained using distilled monoglycerides and thermoplastic corn, pea and rice starch have been characterized by 62-81% higher values of critical stress and 62-93% elongation at rupture, compared with BHC containing sorbitol. The thickness of biodegradable hybrid composite films with monoglycerides is 55-86% less than that of films containing sorbitol in composition of thermoplastic starch. Higher elongation values at rupture and lower film thickness will ensure more effective destruction in environment and more cost-efficient use in packaging.

Soil micromorphological and physical properties after application of composts with polyethylene and biocomponent-derived polymers added during composting

Composts are considered to be one of the best soil amendments. However, the effects of composts with added polymeric materials on soil physical, hydraulic, and micromorphological properties have not been widely discussed. Changes in soil physical properties influence the numerous services that soils provide. We studied the impacts of composts with the addition of three different polymers (F1–F3) produced from polyethylene and thermoplastic corn starch on the physical, hydraulic, and micromorphological properties of two soils, a Cambic Phaeozem and a Luvic Phaeozem. Applying composts with polymers had limited or no significant effect on soil bulk density and porosity, but increased the field water capacity by 18%–82% and 3%–6% and the plant-available water content by 15%–23% and 4%–17% for the Cambic Phaeozem and Luvic Phaeozem, respectively. The application of composts with polymers had a greater effect on the Cambic Phaeozem than on the Luvic Phaeozem. It was suggested that the use of modified composts led to changes in soil physical properties and micromorphological features and this effect was dependent on the compost application rate. Composts made with the addition of composite synthetic and natural material-derived polymers during composting were found to be a composite mixture that can be successfully used in agriculture.