Bi-Functional Biobased Packing of the Cassava Starch,Glycerol, Licuri Nanocellulose and Red Propolis

The aim of this study was to characterize and determine the bi-functional efficacy of active packaging films produced with starch (4%) and glycerol (1.0%), reinforced with cellulose nanocrystals (0–1%) and activated with alcoholic extracts of red propolis (0.4 to 1.0%). The cellulose nanocrystals used in this study were extracted from licuri leaves. The films were characterized using moisture, water-activity analyses and water vapor-permeability tests and were tested regarding their total phenolic compounds and mechanical properties. The antimicrobial and antioxidant efficacy of the films were evaluated by monitoring the use of the active films for packaging cheese curds and butter, respectively. The cellulose nanocrystals increased the mechanical strength of the films and reduced the water permeability and water activity. The active film had an antimicrobial effect on coagulase-positive staphylococci in cheese curds and reduced the oxidation of butter during storage.     

Green composite films prepared from cellulose,starch and lignin in room-temperature ionic liquid

A series of novel biobased composite films derived from cellulose, starch and lignin were prepared from an ionic liquid (IL), 1-allyl-3-methylimidazolium chloride (AmimCl) by coagulating in a nonsolvent condition. The ionic liquid can be recycled with a high yield and purity after the green film was prepared. The uniform design method was applied to investigate mechanical properties of the biobased composite films. The effect of each component and their associated interactive effects were investigated. The experimental results showed that contents of cellulose, lignin and starch had a significant influence on the mechanical properties of composite films. The composite films showed relatively excellent mechanical properties in dry and wet states owing to the mutual property supplement of different components. The composite films were characterized via FT-IR, X-ray diffraction (XRD) and scanning electron microscope (SEM). Their thermal stability and gas permeability were also investigated, and the results showed that the composite films had good thermal stability and high gas barrier capacity and give a CO₂:O₂ permeability ratio close to 1.     

Mechanical,barrier and morphological properties of pea starch and peanut protein isolate blend films

Mechanical, barrier and morphological properties of edible films based on blends of Pea starch (PS) and Peanut protein isolate (PPI) plasticized with glycerol (30%, w/w) were investigated. As PPI ratio in PS/PPI blends increased, the thickness of films decreased, the opacity slightly elevated and color intensified. The addition of PPI to the PS film significantly reduced tensile strength from 5.44 MPa to 3.06 MPa, but increased elongation from 28.56% to 98.12% with the incorporation of PPI into PS at 50% level. Film solubility value fell from 22.31% to 9.78% upon the incorporation of PPI ranged from 0 to 50% level. When PPI was added into PS film at 40% level, the WVP and WVTR of the films markedly dropped from 11.18% to 4.19% and 6.16 to 1.95%, respectively. Scanning electron microscopy (SEM) of the surface of films showed that many swollen starch granules were presented in the 100% PS film, while 100% PPI film was observed to have rougher surfaces with presence of pores or cavities. The PS/PPI blend films upon the incorporation of PPI at 20% and 50% level were not homogeneous. However, the smoother film surface was observed in PS/PPI blend films with the addition of PPI at 40% level. SEM image of the cross-sections of the films revealed that the 100% PS film showed a uniform and compact matrix without disruption, and pore formation and 100% PPI film displayed a smooth structure. Rougher and flexible network was shown in blend film with the addition of PPI reaching 40% level.     

Structure and properties of hydroxyapatite/cellulose nanocomposite films

The aim of this study was to develop a new inorganic-organic hybrid film. Nanohydroxyapaptite (nHAP) particles as the inorganic phase was mixed with cellulose in 7 wt.% NaOH/12 wt.% urea aqueous solution with cooling to prepare a blend solution, and then inorganic-organic hybrid films were fabricated by coagulating with Na₂SO₄ aqueous solution. The structure and properties of the hybrid films were characterized by high resolution transmitting electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), thermo-gravimetric analysis (TGA), Fourier transform infra-red (FT-IR) spectra, wide angle X-ray diffraction (WAXD) and tensile testing. The results revealed that the HAP nanoparticles with mean diameter of about 30 nm were uniformly dispersed and well immobilized in the hybrid film as a result of the role of the nano-and micropores in the cellulose substrate. A strong interaction existed between HAP and cellulose matrix, and their thermal stability and mechanical strength were improved as a result of good miscibility. Furthermore, the results of 293T cell viability assay indicated that the HAP/cellulose films had excellent biocompatibility and safety, showing potential applications in biomaterials.     

Mechanical Properties of Thermo-moulded Biofilms in Relation to Proteins/Starch Interactions

The effects of hydrophilic and hydrophobic characteristics of proteins on the interactions with corn starch were investigated in this study. The model system included corn starch and proteins, i.e. zein, gliadin, gluten, soy protein and rapeseed protein. The blend films were prepared by thermo-moulding in gentle conditions at 70 °C in order to avoid starch gelatinization, with respect to water content, and avoid protein denaturation. The effects of different kinds of proteins on structure and mechanical behaviour of blend biomaterials were characterised by scanning electron microscopy (SEM) and tensile test, respectively. The effects of different kinds of proteins on intermolecular interactions between proteins and starch were investigated by dynamical mechanical thermal analysis. Based on the solubility measurement results, almost all protein films showed the similar solubility to the natural protein powders, resulting from the weak influence of mild thermo-moulding treatment on protein inner structure. Different morphologies were observed for different proteins and corresponding blends, which are relatively loose protein architecture that appeared for hydrophobic protein and blend films, and uniform and densely packed architecture for hydrophilic ones. Moreover, different mechanical behaviours were obtained for different proteins and corresponding blends. No significantly increased strength for hydrophilic protein blends with starch added can be explained that there is weak intermolecular interaction between both components based on SEM observation. However, the addition of corn starch granules in hydrophobic protein networks was assumed that starch destroyed or weakened the protein network, resulting in the decrease of mechanical strength.     

Fabrication and Characterization of Native and Oxidized Potato Starch Biodegradable Films

The need to replace conventional polymers due to environmental pollution caused by them has led to increased production of biodegradable polymers such as starch. Thus, the application possibilities of starch have increased. In this study, we produced and characterized biodegradable films derived from native and oxidized potato starch. The film-forming solution was prepared with different concentrations of extracted starch (native or oxidized) and a plasticizer (glycerol or sorbitol). Then, the mechanical, barrier, morphological, and structural properties of the films were characterized. The moisture content of the films varied from 15.35?±?1.31 to 21.78?±?0.49%. The elastic modulus of the films ranged from 219?±?14.97 to 2299?±?62.91 MPa. The film of oxidized starch plasticized with sorbitol in the lowest content was the most resistant and flexible; moreover, this film also presented lower water vapor permeability and low solubility in water. Fourier-transform infrared spectroscopic analysis of the biodegradable films indicated the presence of same functional groups as those of starch with bands in the same regions. The film thickness was lower for the films plasticized with glycerol whereas the color variation (Δ?) was lower for the ones plasticized with sorbitol. In case of both plasticizers, the increase in their content decreased the Δ? value. All the biodegradable films presented stability against water absorption owing to their low solubility in water. Morphological evaluation revealed the presence of partially gelatinized starch granules in the films. The roughness parameter (Rq) of the films varied from 3.39 to 10.9 nm, indicating that their surfaces are smooth. X-ray diffraction studies showed a B-type pattern for the starches, which is representative of tubers. Further, the films present higher relative crystallinity (RC) compared to the starches. The biodegradable starch films are uniform, transparent and with low solubility in water. The oxidation of starch and use of sorbitol as a plasticizer resulted in improved properties of the starch films, which is suitable for application.     

Nanocomposite films based on xylan-rich hemicelluloses and cellulose nanofibers with enhanced mechanical properties

Interest in xylan-rich hemicelluloses (XH) film is growing, and efforts have been made to prepare XH films with improved mechanical properties. This work described an effective approach to produce nanocomposite films with enhanced mechanical properties by incorporation of cellulose nanofibers (CNFs) into XH. Aqueous dispersions of XH (64-75 wt %), sorbitol (16-25 wt %), and CNF (0-20 wt %) were cast at a temperature of 23 °C and 50% relative humidity. The surface morphology of the films was revealed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thermal properties and crystal structure of the films were evaluated by thermal analysis (TG) and X-ray diffraction (XRD). The surface of XH films with and without CNF was composed primarily of nanonodules, and CNFs were embedded in the XH matrix. Freeze-dried XH powder was amorphous, whereas the films with and without CNF showed a distinct peak at around 2θ = 18°, which suggested that XH molecules aggregated or reordered in the casting solution or during water evaporation. Furthermore, the nanocomposite films had improved thermal stability. XH film with 25 wt % plasticizer (sorbitol, based on dry XH weight) showed poor mechanical properties, whereas incorporation of CNF (5-20 wt %, based on the total dry mixture) into the film resulted in enhanced mechanical properties due to the high aspect ratio and mechanical strength of CNF and strong interactions between CNF and XH matrix. This effective method makes it possible to produce hemicellulose-based biomaterials of high quality.     

Characterization of Corn Starch Films Reinforced with CaCO3 Nanoparticles

The characterization of corn starch (CS) films impregnated with CaCO₃ nanoparticles was investigated. Criteria such as morphology, crystallinity, water vapor permeability (WVP), opacity, and mechanical properties were the focus of the investigation. It was found that the CaCO₃ contents had significant effects on the tensile properties of the nanocomposite films. The addition of CaCO₃ nanoparticles to the CS films significantly increased tensile strength from 1.40 to 2.24 MPa, elongation from 79.21 to 118.98%, and Young’s modulus from 1.82 to 2.41 MPa. The incorporation of CaCO₃ nanoparticles increased the opacity of films, lowered the degree of WVP and film solubility value compared to those of the CS films. The results of scanning electron microscopy (SEM) showed that with the increase of CaCO₃ nanoparticles content in starch films, the roughness of the films increased, and pores or cavities were found on the surface of the films, while small cracks were observed in the structures of the fractured surfaces. X-ray diffraction showed that the addition of nanoparticles increased the peaks in the intensity of films.     

Characterization of cellulose acetate-reinforced aliphatic-aromatic copolyester composites

The biodegradability, morphology, mechanical, and thermal properties of composite materials composed of maleic anhydride-grafted poly(butylene adipate-co-terephthalate) (PBAT) and cellulose acetate (CA) were evaluated. Composites containing maleic anhydride-grafted PBAT (PBAT-g-MA/CA) exhibited noticeably superior mechanical properties due to greater compatibility between the two components. The dispersion of CA in the PBAT-g-MA matrix was highly homogeneous as a result of ester formation, and the consequent creation of branched and cross-linked macromolecules between the anhydride carboxyl groups of PBAT-g-MA and hydroxyl groups in CA. Each composite was buried in soil and monitored to assess biodegradability. Both the PBAT and the PBAT-g-MA/CA composite films were eventually completely degraded, and severe disruption of film structure was observed after 60-100 days of incubation. Although the degree of weight loss after burial indicated that both materials were biodegradable, even with high levels of CA, the higher water resistance of PBAT-g-MA/CA films indicated that they were more biodegradable than those made of PBAT.     

Novel regenerated cellulose films prepared by coagulating with water: Structure and properties

Regenerated films were successfully prepared from cellulose/NaOH/urea solution by coagulating with water at temperature from 25 to 45 °C. The results of solid ¹³C NMR, wide angle X-ray diffraction, scanning electron microscopy (SEM) and tensile testing revealed that the cellulose films possessed homogeneous structure and cellulose II crystalline, similar to that prepared previously by coagulating with 5 wt% H₂SO₄. By changing the coagulation temperature from 25 to 45 °C, tensile strength of the films was in the range of 85-139 MPa. Interestingly, the RC35 film coagulated at 35 °C exhibited the highest tensile strength (σ_b = 139 MPa). The inclusion complex associated with cellulose, NaOH and urea hydrates in the cellulose solution were broken by adding water (non-solvent), leading to the self-association of cellulose to regenerate through rearrangement of the hydrogen bonds. This work provided low-cost and “green” pathway to prepare cellulose films, which is important in industry.     

Characterization of edible emulsified films with low affinity to water based on kefiran and oleic acid

New edible composite films based on kefiran and oleic acid (OA) at the ratio of 15, 25, and 35% (w/w) were prepared using emulsification with the aim of improving their water vapour barrier and mechanical properties. Film-forming solutions were characterized in terms of rheological properties and particle-size distribution. The impact of the incorporation of OA into the film matrix was studied by investigating the physical, mechanical, and thermal properties of the films. The water vapour permeability (WVP) of the emulsified films was reduced by approximately 33% by adding OA. The mechanical properties of kefiran films were also affected by adding OA: tensile strength was diminished, and elongation increased considerably. Differential scanning calorimetry showed that the glass transition temperature (T_g) of the kefiran film was −16 °C and was not considerably affected by adding OA. Therefore, OA could be incorporated into these films for some food-technology applications that need a low affinity toward water.     

Preparation and characterization of surface crosslinked TPS/PVA blend films

Surface crosslinked thermoplastic starch (TPS)/PVA blend films were prepared by applying ultra violet (UV) irradiation. Sodium benzoate was used as photosensitizer and induced onto film surface layer by soaking the TPS/PVA films in the photosensitizer aqueous solution. The effects of concentration of photosensitizer aqueous solution, soaking time and UV irradiation dose on the surface photocrosslinking reaction were investigated. Physical properties, such as water contact angle, moisture absorption, swelling degree and solubility in water as well as mechanical properties of the films were measured to characterize the influence of the surface photocrosslinking modification. The obtained results showed that the surface modification considerably reduced the surface hydrophilic character of the TPS/PVA films, enhanced the film’s water resistance and also increased tensile strength and Young’s modulus but decreased elongation at break of the films.     

Cellulose Acetate Butyrate: Ammonio Methacrylate Copolymer Blends as a Novel Coating in Osmotic Tablets

The objective of this work was the preparation of osmotic tablets using polymer blends of cellulose acetate butyrate (CAB) or ethylcellulose with ammonio methacrylate copolymer (Eudragit® RL). The advantage of these coatings in comparison to the traditionally used cellulose acetate is their solubility in safer organic solvents like ethanol. Polymer films were characterized with respect to their water uptake, dry mass loss, and mechanical properties. The effect of the polymer blend ratio on drug release and on the rupture force of the coating was investigated. In addition, the effect of drug solubility and content, pH and agitation rate of the release medium, and coating level and plasticizer content on the release were studied. With increased Eudragit® RL content in the coating blends, higher medium uptake of the film was observed, resulting in shorter lag times and faster drug release from the osmotic tablets. Replacing ethylcellulose with cellulose acetate butyrate as a coating material led to shorter lag times and faster drug release due to increased film permeability. In addition, CAB-based films had a higher strength and flexibility. The drug release was osmotically controlled and decreased with increasing coating level. It increased with increased drug solubility, plasticizer content, change of buffer species (acetate > phosphate), and decreased coating level. Agitation rate and drug content had no effect on the drug release. A 20% w/w coating level was sufficient for the tablet to tolerate forces of more than five times of the gastric destructive force reported in literature.     

The plasticizing mechanism and effect of calcium chloride on starch/poly(vinyl alcohol) films

Starch/poly(vinyl alcohol) (PVA) films were prepared with calcium chloride (CaCl(2)) as the plasticizer. The micro morphology of pure starch/PVA film and CaCl(2) plasticized starch/PVA film was observed by scanning electron microscope. The interaction between CaCl(2) and starch/PVA molecules was investigated by Fourier transform infrared spectroscopy. The influence of CaCl(2) on the crystalline, thermal and mechanical properties of starch/PVA films was studied by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and tensile testing, respectively. The results indicated that CaCl(2) could interact with starch and PVA molecules and then effectively destroy the crystals of starch and PVA. Starch/PVA films plasticized with CaCl(2) became soft and ductile, with lower tensile strength and higher elongation at break compared with pure starch/PVA film. The water content of starch/PVA film would increase with the addition of CaCl(2). This is an important cause of the plasticization of CaCl(2) on starch/PVA film.     

Extrusion of pectin/starch blends plasticized with glycerol

The microstructural and thermal dynamic mechanical properties of extruded pectin/starch/glycerol (PSG) edible and biodegradable films were measured by scanning electron microscopy (SEM) and thermal dynamic mechanical analysis (TDMA). SEM revealed that the temperature profile (TP) in the extruder and the amount of water present during extrusion could be used to control the degree to which the starch was gelatinized. TDMA revealed that moisture and TP during extrusion and by inference the amount of starch gelatinization had little effect on the mechanical properties of PSG films. Furthermore, TDMA revealed that PSG films underwent a glass transition commencing at about −50°C and two other thermal transitions above room temperature. Finally, it was concluded that the properties of extruded PSG films were comparable to those cast from solution.     

Biodegradability and mechanical properties of starch films from Andean crops

Different Andean crops were used to obtain starches not previously reported in literature as raw material for the production of biodegradable polymers. The twelve starches obtained were used to prepare biodegradable films by casting. Water and glycerol were used as plasticizers. The mechanical properties of the starch based films were assessed by means of tensile tests. Compost tests and FTIR tests were carried out to assess biodegradability of films. The results show that the mechanical properties (UTS, Young's modulus and elongation at break) of starch based films strongly depend on the starch source used for their production. We found that all the starch films prepared biodegrade following a three stage process and that the weight loss rate of all the starch based films tested was higher than the weight loss rate of the cellulose film used as control.     

Investigations about dissolution of cellulose in the 1-allyl-3-alkylimidazolium chloride ionic liquids

In this work, the 1-allyl-3-alkylimidazolium chloride ionic liquids were synthesized and characterized by increasing carbon atoms (n ≤ 6) of alkyl chains on a cationic 3-imidazole ring. The results indicated that 1-allyl-3-alkylimidazolium chloride with asymmetrical structure on the two sides of a cationic 3-imidazole ring (i.e., n = 1, 2, 6) exhibited alkalinity and lower thermal stabilities, and showed better solubility to the cellulose samples at 60-120 °C than those with symmetrical structures (n = 3, 4). The cellulose samples treated by 20% (w/w) ethylenediamine solution showed better solubility in 1-allyl-3-ethyl, hexyl-imidazolium chloride ionic liquids than that treated with 20% (w/w) NaOH solution at 5 °C for 72 h. XRD and TG analysis indicated that 0 0 2 plane apparent crystallite size as well as thermal stability of the regenerated cellulose samples from the ionic liquids decreased significantly compared with the untreated cellulose samples.     

Preparation of cellulose films from solution of bacterial cellulose in NMMO

Bacterial cellulose (BC) was dissolved in N-methylmorpholine N-oxide (NMMO) to prepare regenerated BC films (RBC) with phase inversion. The solubility of BC, supermolecule on structure, morphology, thermal and physical properties of the films were investigated by Fourier transform infrared spectroscopy (FT-IR), solid-state cross polarization/magic angle spinning ¹³C nuclear magnetic resonance (CP/MAS ¹³C NMR), wide-angle X-ray diffraction (WAXD), scanning electron microscope (SEM), and thermogravimetric analysis (TGA). The investigation suggested BC was dissolved completely in NMMO. From the C₆ signal shifts to the amorphous area, the crystallinity of materials decreased from 79.20% to 38.17%, and the transformation from cellulose I to II occurred. It was also found that the banded structure of the native materials was replaced by homogeneous and densified sections, so RBC films had better mechanical and barrier properties, and do thermal stability was similar to that of the native BC.     

Biocomposites of thermoplastic starch with surfactant

Thermoplastic starch films were prepared by a casting technique. Microfibrillated fibers from husks of corncobs were added as reinforcing agents and glyceryl monostearate (GMS) as surfactant. The films were characterized using X-ray diffraction studies, thermal and mechanical analysis and water uptake experiments. Differential scanning calorimetry (DSC) and X-ray diffraction showed the formation of amylose–GMS complexes. Compared to films without GMS the films with GMS showed significant reductions in water uptake and an increase in tensile strength. Important differences in the DSC measurements in the 160–200 °C range of films with and without GMS were also exhibited. These effects can be related to the reinforcement of the polymer matrix by the web-like network of the microfibrillated fibers, the formation of amylose–GMS complexes and the interactions of the polar groups of the GMS with the hydroxyl groups of the cellulose. Retrogradation tendencies of the TPS films were also changed by these phenomena.     

Physical, chemical and mechanical properties of pehuen cellulosic husk and its pehuen-starch based composites

Pehuen cellulosic husk was characterized and employed as reinforcement for composite materials. In this research, thermoplastic pehuen starch (TPS) and TPS/poly(lactic acid) (PLA)/polyvinyl alcohol (PVA) composites, reinforced with 5 and 10% of pehuen husk, were prepared by melt-blending. Comparative samples of pehuen TPS and TPS/PLA/PVA blend were also studied. Physical, thermal, structural and mechanical properties of composites were evaluated. Pehuen husk mainly consists of cellulose (50wt%), hemicellulose (30wt%) and lignin (14wt%). In respect to lipids, this husk has only a 0.6wt%. Its surface is smooth and damage-free and it is decomposed above 325°C. The incorporation of pehuen husk improved considerably the thermal stability and mechanical properties of the studied composites, mainly in TPS composites. Their thermal stability enhances since biofiber hinders the "out-diffusion" of volatile molecules from the polymer matrix, while mechanical properties could raise due to the natural affinity between husk and starch in the pehuen seed.