Influence of Polyol Plasticizers on the Properties of Polyvinyl Alcohol Films Fabricated by Melt Processing

In this work, high-alcoholysis polyvinyl alcohol (PVA) films were fabricated by melt processing and the plasticizing effect of compound polyol plasticizers on PVA were investigated with X-ray diffraction (XRD), differential scanning calorimetry (DSC), rheological measurements, mechanical tests etc. Hydrogen bonding interactions occurred between PVA and plasticizer. With the increase of plasticizer, the flowability of PVA was improved and reached the maximum value at the plasticizer of 20%. Glass transition temperature (T _g) and melting point (T _m) decreased with the increase of plasticizer content. For the heterogeneous nucleation effect of plasticizer, new polymorph of PVA formed. The viscosity was sensitive to the shear rates. The incorporation of plasticizers into PVA resulted in the increase of elongation at break and impact strength, as well as the decrease of tensile strength.     

Comparison of the Effect of Plasticizers on PHBV—and Organoclay—Based Biodegradable Polymer Nanocomposites

The aim of this work was to evaluate the effect of different plasticizers on the morphology, crystallization, and mechanical properties of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/organomodified montmorillonite (OMt) nanocomposites. We investigated three different plasticizers: dioctyl phthalate (DOP), a commonly used additive in the polymer industry, and two natural and biodegradable plasticizers: epoxidized soybean oil (ESO) and triethyl citrate (TEC). The nanocomposites with 3 wt% OMt were obtained by melt processing in an internal mixer. The plasticizers were used alone or in combination with clay in a concentration of 10 wt%. X-ray diffraction and scanning electron microscopy results revealed a partially intercalated structure. The degree of crystallinity was higher for all of the samples compared to neat PHBV, although the melting temperature decreased with the use of plasticizers combined with OMt. The impact strength results were dependent on the interaction between the components of the system. Triethyl citrate was the most effective plasticizer due to its more pronounced interaction with the PHBV matrix, which yielded improvements in processing conditions and PHBV’s flexibility and impact properties.     

Production and Characterization of Bioplastics Obtained by Injection Moulding of Various Protein Systems

Bioplastic materials from renewable polymers, like proteins, constitute a highly interesting field for important industrial applications such as packaging, agriculture, etc., in which thermo-mechanical techniques are increasingly being used. This study assesses bioplastic materials produced by injection from blends previously prepared in a batch mixer using various protein concentrates and isolates. A mixing time of 5 min has been selected in order to ensure correct homogenous blends. A comparison between different protein-based specimens was performed by dynamic mechanical thermal analysis, tensile strength, water uptake and transmittance tests. The comparison reveals that the protein nature and the percentage of plasticizer lead to bioplastics with different properties and, consequently, different applications. Protein concentrates and isolates, wastes and surpluses from the food industry, may be useful for producing bioplastics with suitable mechanical properties and processability, as well as biodegradability, by means of suitable mixing and injection moulding conditions.     

Environmentally Friendly Oil-Modified Polyesters as Polymeric Plasticizers for Poly(vinyl chloride)

Oil-modified polyesters were synthesized to serve as polymeric plasticizers for PVC. A total of four polymeric plasticizers with different average molecular weights were prepared. Characterizations were done using Fourier-transformed infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Some of the tests conducted on PVC films include thermal stability test using thermogravimetric analyser, determination of glass transition temperature (T_g), plasticizer migration and leaching resistance test, morphology study of plasticized PVC films using field emission scanning microscope, toxicity test, and tensile test. Owing to the plasticizing effect of the palm oil-based compound, T_g of the plasticized PVC has decreased to an average of 65 °C at 20 wt% loading. The polymeric plasticizer is also able to contribute positively to the thermal stability and mechanical properties of the PVC films. Some of the advantages of incorporating polymeric plasticizer with high molecular weight includes lower rate of leaching from plastic, and improved tensile strength and elongation at break. Besides, thermal stability of the plastic studied using Kissinger’s and Flynn–Wall–Ozawa’s approaches shows that PVC blended with high molecular weight oil-modified polyester is more thermally stable, evidenced by the increase in the activation energy of decomposition, E_d. Toxicity test using brine shrimp egg shows encouraging results, where the oil-based plasticizer is considerably less toxic compared to some of the commercial plasticizers.     

Films Made by Blending Poly(ε-Caprolactone) with Starch and Flour from Sagu Rhizome Grown at the Venezuelan Amazons

Starch-based composite films have been proposed as food packaging. In this context, the study of non-conventional starch sources (sagu, Canna edulis Kerr) has worldwide special attention, because these materials can impart different properties as carbohydrate polymers. A thorough study of the matrices used (sagu starch and flour) was carried out. In the same way, thermoplastic starch (TPS)/PCL blend and thermoplastic flour (TFS)/PCL blend were obtained by melt mixing followed by compression moulding containing glycerol as plasticizer. In this study, chemical composition of the matrices and their properties were related with the properties of the developed films. Moisture content, water solubility, X-ray diffraction, thermogravimetric analysis and mechanical and microstructural properties were evaluated in the films. Taking into account the results, the sagu flour has great potential as starchy source for food packaging applications. However, concretely the flour had lower compatibility with the PCL compared to the starch/PCL blend.     

Preparation and Properties of Propylene Glycol Plasticized Wheat Protein Isolate Novel Green Films

Novel bio-based green films were prepared using wheat protein isolate (WPI) by solution casting method using Propylene Glycol as a plasticizer for packaging applications. The effect of the plasticizer content (10, 15, 20 and 25 wt%) on mechanical properties (tensile strength, young’s modulus and  % of elongation) was investigated. A thermal degradation and phase transition of the prepared WPI was assessed by means of TGA and DSC analysis. The results showed that the tensile strength and young’s modulus decreased and  % of elongation increased with increasing PG content. The ATR-FTIR and SEM were used for structural characterization and morphology of the films, respectively. FTIR studies reveals that the intensity of the bands corresponding to the amide groups increases with increasing PG content tending to increase protein–PG interactions. Further, the glass transition temperature was decreased and the thermal stability of the WPI was found to be increased by plasticization. The overall thermal stability of the films was improved and is attributed to the increase in mobility of the polymer chains.     

Biodegradation of Polylactide and Gelatinized Starch Blend Films Under Controlled Soil Burial Conditions

The biodegradability of polylactide (PLA) and gelatinized starches (GS) blend films in the presence of compatibilizer was investigated under controlled soil burial conditions. Various contents (0–40 wt%) of corn and tapioca starches were added as fillers; whereas, different amounts of methylenediphenyl diisocyanate (MDI) (0–2.5 wt%) and 10 wt% based on PLA content of polyethylene glycol 400 (PEG400) were used as a compatibilizer and a plasticizer, respectively. The biodegradation process was followed by measuring changes in the physical appearance, weight loss, morphological studies, and tensile properties of the blend films. The results showed that the presence of small amount of MDI significantly increased the tensile properties of the blends compared with the uncompatibilized blends. This is attributed to an improvement of the interfacial interaction between PLA and GS phases, as evidenced by the morphological results. For soil burial testing, PLA/GS films with lower levels (1.25 wt%) of MDI had less degradation; in contrast, at high level of MDI, their changes of physical appearance and weight loss tended to increase. These effects are in agreement with their water absorption results. Furthermore, biodegradation rates of the films were enhanced with increasing starch contents, while mechanical performances were decreased.     

Synthesis and Characterization of Lactic Acid Oligomers: Evaluation of Performance as Poly(Lactic Acid) Plasticizers

The use of fully bio-based and biodegradable materials for massive applications, such as food packaging, is an emerging tendency in polymer research. But the formulations proposed in this way should preserve or even increase the functional properties of conventional polymers, such as transparency, homogeneity, mechanical properties and low migration of their components to foodstuff. This is not always trivial, in particular when brittle biopolymers, such as poly(lactic acid) (PLA), are considered. In this work the formulation of innovative materials based on PLA modified with highly compatible plasticizers, i.e. oligomers of lactic acid (OLAs) is proposed. Three different synthesis conditions for OLAs were tested and the resulting additives were further blended with commercial PLA obtaining transparent and ductile materials, able for films manufacturing. These materials were tested in their structural, thermal and tensile properties and the best formulation among the three materials was selected. OLA with molar mass (M_n) around 1,000 Da is proposed as an innovative and fully compatible and biodegradable plasticizer for PLA, able to replace conventional plasticizers (phthalates, adipates or citrates) currently used for films manufacturing in food packaging applications.     

Mechanical Properties, Water Vapor Permeability and Water Affinity of Feather Keratin Films Plasticized with Sorbitol

In poultry industry chicken feathers are normally hydrolyzed and used to prepare animal feed. In this work the use of this material to prepare films was investigated. Keratins were extracted from chicken feathers with 2-mercaptoethanol in concentrated urea solution using sodium dodecyl sulfate (SDS). The effect of varying the amount of sorbitol on properties of chicken feather keratin (CFK) was investigated. As the concentration of plasticizer increased, the moisture content (MC) of these films increase, the monolayer MC increased from 0.060 (without plasticizer) to 0.482 g water/g dry matter (0.30 g sorbitol/g keratin). The water vapor permeability (WVP) varied between 0.096 g/m s Pa and 8.098 g/m s Pa for films without sorbitol and with 0.30 g sorbitol/g keratin, respectively. Film strength decreased from 5.13 MPa to 0.45 MPa and the elongation at break achieved the maximum value of 52.75% for samples with 0.02 g sorbitol/g keratin. The dry matter density didn’t change significantly, varying between 0.86–0.89 g/cm³ for all samples. Films with potential applications in food packaging can be obtained from CFKs. However, further researches are necessary to decrease film solubility and increase mechanical resistance.     

Chitosan/Hydrophilic Plasticizer-Based Films: Preparation,Physicochemical and Antimicrobial Properties

The addition of plasticizers to biopolymer films is a good method for improving their physicochemical properties. The aim of this study was to evaluate the effect of chitosan (CHI) blended with two hydrophilic plasticizers glycerol (GLY) and sorbitol (SOR), at two concentrations (20 and 40 wt%) on their mechanical, thermal, barrier, structural, morphological and antimicrobial properties. The chitosan was prepared through the alkaline deacetylation of chitin obtained from fermented lactic from shrimp heads. The obtained chitosan had a degree of deacetylation (DA) of 84 ± 2.7 and a molecular weight of 136 kDa, which indicated that a good film had formed. The films composed of CHI and GLY (20 wt%) exhibited the best mechanical properties compared to the neat chitosan film. The percentage of elongation at break increase to over 700 % in the films that contained 40 % GLY, and these films also exhibited the highest values for the water vapor transmission rate (WVTR) of 79.6 ± 1.9 g m² h^?1 and a yellow color (b _o  = 17.9 ± 2.0) compared to the neat chitosan films (b _o  = 8.8 ± 0.8). For the structural properties, the Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analyses revealed an interaction in the acetamide group and changes in the crystallinity of plasticized films. The scanning electron micrographs revealed that all formulations of the chitosan films were smooth, and that they did not contain aggregations, pores or microphase separation. The thermal analysis using differential scanning calorimetry (DSC) revealed a glass transition temperature (Tg) of 130 °C for neat chitosan film, but the addition of SOR or GLY elicited a decrease in the temperature of the peak (120 °C). In addition, the antimicrobial activity of the chitosan films was evaluated against Listeria monocytogenes, and reached a reduction of 2 log after 24 h. The plasticizer concentration of 20 % GLY is sufficient for obtaining flexible chitosan films with good mechanical properties, and it could serve as an alternative as a packaging material to reduce environmental problems associated with synthetic packaging films.     

Properties of Starch/PVA Blend Films Containing Citric Acid as Additive

Starch/polyvinyl alcohol (PVA) blend films were prepared successfully by using starch, polyvinyl alcohol (PVA), glycerol (GL) sorbitol (SO) and citric acid (CA) for the mixing process. The influence of mixing time, additional materials and drying temperature of films on the properties of the films was investigated. With increase in mixing time, the tensile strength (TS), elongation (%E), degree of swelling (DS) and solubility (S) of the film were equilibrated. The equilibrium for TS, %E, DS and S value was 20.12 MPa, 36.98%, 2.4 and 0.19, respectively. The mixing time of equilibrium was 50 min. TS, %E, DS and S of starch/PVA blend film were examined adding glycerol (GL), sorbitol (SO) and citric acid (CA) as additives. At all measurement results, except for DS, the film adding CA was better than GL or SO because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA and additives. Citric acid improves the properties of starch/PVA blend film compared to glycerol and sobitol. When the film was dried at low temperature, the properties of the films were clearly improved because the hydrogen bonding was activated at low temperature.     

Biodegradable Blends with Potential Use in Packaging: A Comparison of PLA/Chitosan and PLA/Cellulose Acetate Films

Poly(lactic acid) (PLA) is a biodegradable polymer that exhibits high elastic modulus, high mechanical strength, and feasible processability. However, high cost and fragility hinder the application of PLA in food packaging. Therefore, this study aimed to develop flexible PLA/acetate and PLA/chitosan films with improved thermal and mechanical properties without the addition of a plasticizer and additive to yield extruder compositions with melt temperatures above those of acetate and chitosan. PLA blends with 10, 20, and 30 wt% of chitosan or cellulose acetate were processed in a twin-screw extruder, and grain pellets were then pressed to form films. PLA/acetate films showed an increase of 30 °C in initial degradation temperature and an increase of 3.9 % in elongation at break. On the other hand, PLA/chitosan films showed improvements in mechanical properties as an increase of 4.7 % in elongation at break. PLA/chitosan film which presented the greatest increase in elongation at break proved to be the best candidate for application in packaging.     

Bioabsorbable Soy Protein Plastic Composites: Effect of Polyphosphate Fillers on Biodegradability

The use of biodegradable polymers made from renewable agricultural products such as soy protein isolate has been limited by the tendency of these materials to absorb moisture. A straightforward approach for controlling the inherent water absorbency of the biodegradable polymers involves blending special bioabsorbable polyphosphate fillers, biodegradable soy protein isolate, plasticizer, and adhesion promoter in a high-shear mixer followed by compression molding. The procedure yields a relatively water-resistant, biodegradable soy protein polymer composite, as previously reported. The aim of the present study is to determine the biodegradability of the new polyphosphate filler/soy protein plastic composites by monitoring the carbon dioxide released over a period of 120 days. The results suggest that the composites biodegrade satisfactorily, with the fillers having no significant effect on the depolymerization and mineralization of the soy protein plastic, processes that would otherwise result in nonbiodegradable composites. Further, the results indicate that the biodegradation and useful service life of these biocomposites may be controlled by changing the filler concentration, making the biocomposites useful in applications in which the control of water resistance and biodegradation is critical.     

Effect of Orientation on the Morphology and Mechanical Properties of PLA/Starch Composite Filaments

Polylactic acid (PLA)/starch fibers were produced by twin screw extrusion of PLA with granular or gelatinized starch/glycerol followed by drawing through a set of winders with an intermediate oven. At 30% starch, fibers drawn 2–5x were highly flexible (elongation 20–100%) while undrawn filaments were brittle (elongation 2–9%). Tensile strength and moduli increased with increasing draw ratio but decreased with increasing starch content. Mechanical properties were better for composites made with gelatinized starch/glycerol than granular starch. In conclusion, orientation greatly increases the flexibility of PLA/starch composites and this may be useful not only in fibers but also possibly in molded articles. Other advantages of starch addition could include fiber softness without added plasticizer, moisture/odor absorbency and as a carrier for active compounds.     

Effect of Manufacturing Process and Xanthan Gum Addition on the Properties of Cassava Starch Films

The objective of this work was to manufacture biodegradable films by two different processes (casting and extrusion), from different combinations of cassava starch and xanthan gum. These films were produced by casting and by extrusion from six different starch-xanthan gum combinations (0, 2, 4, 6, 8 and 10% w/w), containing glycerol as plasticizer (20% w/w) and were also characterized according to their microstructure, optical, mechanical, and barrier properties. Scanning electron microscopy of the starch-xanthan gum extruded films showed reticulated surface and smooth interior, suggesting that xanthan was driven to the surface and gelatinized starch to the interior of the films during extrusion. Films manufactured by casting were entirely homogeneous. In general, casted films presented lower opacity and water vapor permeability and higher stress at break than films manufactured by extrusion. Xanthan gum addition affected mechanical properties of starch films, improving their stress and strain at break, especially for extruded samples, but these properties did not show stability at different RH conditions.     

Biodegradation of γ Irradiated Poly 3-hydroxybutyrate (PHB) Films Blended with Poly(Ethyleneglycol)

Poly(3-hydroxybutyrate) (PHB) was evaluated in blends with poly(ethyleneglycol) (PEG) of different weight average molecular weight (Mw = 300, 600, 1,000 and 6,000). Irradiation of the PHB/PEG films was carried out to different levels of irradiation doses (5 and 10 kGy) and the effects were investigated talking into consideration: thermal properties by differential scanning calorimetry (DSC), perforation resistance, water vapor transmission rate and biodegradation in simulated soil. The addition of plasticizer alters thermal stability and crystallinity of the blends. The improvement in perforation resistance due to irradiation was regarded to be a result of the crosslinking effect. Also, biodegradation assays resulted in mass retention improvements with increases in PEG molar masses, PEG concentration and irradiation dose. The irradiation process was shown to hamper the biodegradation mechanism.     

Mineralization of Poly(ɛ-caprolactone)/Adipate Modified Starch Blend in Agricultural Soil

The biodegradability properties of poly(ɛ-caprolactone) (PCL) and modified adipate-starch (AS) blends, using Edenol-3203 (E) as a starch plasticizer, were investigated in laboratory by burial tests of the samples in previously analyzed agricultural soil. The biodegradation process was carried out using the respirometric test according to ASTM D 5988-96, and the mineralization was followed by both variables such as carbon dioxide evolution and mass loss. The results indicated that the presence of AS-E accelerated the biodegradation rate as expected.     

Biodegradable Films Based on Blends of Gelatin and Poly (Vinyl Alcohol): Effect of PVA Type or Concentration on Some Physical Properties of Films

The aim of this work was to develop biodegradable films based on blends of gelatin and poly (vinyl alcohol) (PVA), without a plasticizer. Firstly, the effect of five types of PVA with different degree of hydrolysis (DH) on the physical properties of films elaborated with blends containing 23.1% PVA was studied. One PVA type was then chosen for the study of the effect of the PVA concentration on the mechanical properties, color, opacity, gloss, and water solubility of the films. The five types of PVA studied allowed for films with different characteristics, but with no direct relationship with the DH of the PVA. Therefore, the PVA Celvol^®418 with a DH = 91.8% was chosen for the second part, because they produced films with greater tensile strength. The PVA concentration affected all studied properties of films. These results could be explained by the results of the DSC and FTIR analyses, which showed that some interactions between the gelatin and the PVA occurred depending on the PVA concentration, affecting the crystallinity of the films.     

A Study of Dynamic Mechanical and Thermal Behavior of Starch/Poly(vinylalcohol) Based Films

Starch/Poly(vinylalcohol) blends in two different ratios (60:40 and 50:50) were prepared with glycerol as a plasticizer. Films were cast by a solution casting method. One set of films were filled with 10 wt% of bentonite clay and another set of films were crosslinked with epichlorohydrin in an alkaline medium. The prepared film samples were characterized with dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). The presence of clay and crosslinking with epichlorohydrin was found to have considerable effect on the dynamic mechanical properties and thermal stability of the films. Intercomponent H-bonding between starch, Poly(vinylalcohol) and glycerol enhanced the thermal stability of the films. But incorporation of clay and crosslinking with epichlorohydrin enhanced the steric crowding and lowered the thermal stability of the films.     

A Comparison Study of Wheat Gluten Composites Filled with Dialdehyde Starch and Native Starch

Environmentally friendly green composites were prepared by blending Wheat gluten (WG) as matrix, dialdehyde starch (DAS) as filler and glycerol as plasticizer followed by compression molding of the mixture at 110 °C. The properties of the WG/DAS composite are compared with those of the WG/native wheat starch (NWS) composites. While tensile strength and strain at break decrease with increasing NWS content in the WG/NWS composites, a small content of DAS could improve tensile strength and strain at break simultaneously in the WG/DAS composites. The WG/DAS composites exhibit reduced moisture absorption in comparison with the WG/NEW composites. Formation of chemical bonding between DAS and WG is beneficial for the dispersion of DAS in the WG matrix and WG/DAS composites exhibit improved mechanical properties and reduced moisture absorption over the WG/NWS composites.