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.     

The Effect of Acetylation on the Hydrolytic Degradation of PLA/Clay Nanocomposites

In this study, the hydrolytic degradation of Poly(lactic acid) (PLA) and acetylated PLA (PLA-Ac)–clay nanocomposites were investigated. The organo clay was obtained by ion exchange reaction using cetyl tri methyl ammonium bromide (CTAB). Nanocomposites containing 2, 5 and 8% mass ratio of organo clay (CTAB-O) were prepared. PLA and its organo clay nanocomposites were characterized by scanning electron microscope (SEM), thermo gravimetric analysis (TGA) and X-ray diffraction (XRD) to determine the morphology before and after hydrolytic degradation. Fourier transform infrared (FTIR) analyses of PLA and PLA-Ac were also obtained. The hydrolytic degradation of polymers and their composites were investigated in the phosphate buffered saline solution (PBS). The results showed that controlled hydrolytic degradation was observed in the samples with end group modification of PLA. While weight loss of PLA films was 28%, that of PLA-Ac films was 18% after 60 days degradation time. The weight loss was obtained as 29.5 and 25.5% for PLA-5 wt% organo clay (PLA/5CTAB-O) and PLA-Ac-5 wt% organo clay (PLA-Ac/5CTAB-O) nanocomposites films, respectively. It was also observed that thermal degradation of PLA-Ac was much more than that of PLA. Hydrolytic degradation increased depending on organo clay content. The end group modificated PLA results in controlled hydrolytic degradation. While hydrolytic degradation in polymer films occurred as surface erosion, bulk erosion was observed in composite films.     

Nanocomposite Film Based on Gluten Modified with Heracleum persicum Essence/MgO/Polypyrrole: Investigation of Physicochemical and Electrical Properties

In this study, the wheat gluten film was prepared. Heracleum persicum essence, magnesium oxide nanoparticles and polypyrrole were used to modify the structure of the wheat gluten film. Physicochemical properties of the prepared films such as thickness, solubility, moisture absorption ability, antioxidant properties, and electrical conductivity of the films were investigated. Also, the mechanical, structural and thermal properties of the films were investigated by techniques such as SEM, FTIR, XRD, TGA, DTA and tissue analysis. SEM images showed that the essence and polypyrrole strengthened the gluten film structure and made it more resistant to the passage of gases. FTIR spectra confirmed the electrostatic interactions between gluten and essence and polypyrrole. XRD spectra showed the amorphous structure of gluten film and its composites. The results of thermal analysis showed that polypyrrole greatly increased the thermal resistance of the film and the nanoparticles had little effect on the thermal resistance. Thickness, solubility, moisture content and ability to absorb moisture were further affected by the essential oil. The antioxidant and electrical conductivity of the film was greatly increased in the presence of all three additives of essence, magnesium oxide nanoparticles and polypyrrole. The gluten–essence–MgO–PPy (Glu–E–MgO–PPy) composite film had the most antioxidant properties. Glu–E–MgO–PPy film with important electrical conductivity and antioxidant properties has the potential to be used as an active and intelligent film in the packaging of perishable food products.

     

Preparation and Characterization of Gamma Irradiated Sugar Containing Starch/Poly (Vinyl Alcohol)-Based Blend Films

Blends based on different ratios of starch (35–20%) and plasticizer (sugar; 0–15%) keeping the amount of poly(vinyl alcohol) (PVA) constant, were prepared in the form of thin films by casting solutions. The effects of gamma-irradiation on thermal, mechanical, and morphological properties were investigated. The studies of mechanical properties showed improved tensile strength (TS) (9.61 MPa) and elongation at break (EB) (409%) of the starch-PVA-sugar blend film containing 10% sugar. The mechanical testing of the irradiated film (irradiated at 200 Krad radiation dose) showed higher TS but lower EB than that of the non-radiated film. FTIR spectroscopy studies supported the molecular interactions among starch, PVA, and sugar in the blend films, that was improved by irradiation. Thermal properties of the film were also improved due to irradiation and confirmed by thermo-mechanical analysis (TMA), differential thermo-gravimetric analysis (DTG), differential thermal analysis (DTA), and thermo-gravimetric analysis (TGA). Surface of the films were examined by scanning electron microscope (SEM) image that supported the evidence of crosslinking obtained after gamma irradiation on the film. The water up-take and degradation test in soil of the film were also evaluated. In this study, sugar acted as a good plasticizing agent in starch/PVA blend films, which was significantly improved by gamma radiation and the prepared starch-PVA-sugar blend film could be used as biodegradable packaging materials.     

Modification of Thermo-Mechanical Properties of Recycled PET by Vinyl Acetate (VAc) Monomer Grafting Using Gamma Irradiation

Vinyl acetate (VAc) monomer of different percentage was grafted onto the recycled polyethylene terephthalate (r-PET) films using gamma irradiation. The properties of these modified films were characterized by Fourier transform infrared spectroscopy (FTIR), mechanical properties testing (Tensile strength, Elongation at break), dynamic mechanical analysis (DMA) and thermo-gravimetric analysis (TGA). The Tensile Strength (TS) of the modified PET film increased by 132.25?% to the highest value of 50.12 MPa at 15% VAc monomer concentration at 3 kGy gamma dose, while the elongation at break (EB) decreased by 31.83?%. FTIR was used to investigate the molecular interaction of the modified films. TGA revealed that curve of the modified PET film shifted toward higher temperature region by 95?°C, which is very close to that of PET film made from virgin flakes. The results indicate that modified PET films of better mechanical and thermal properties were successfully prepared using VAc monomer grafting by gamma irradiation technique.     

Formulation of a Photosensitized Polyethylene Film; Its Structure and Property Variation Under the Weathering Conditions of Tehran

To develop an environmentally degradable polymer material, a masterbatch pro-oxidant system was blended into low-density polyethylene. The polymer film samples were prepared by compression molding. The prepared films were placed under the natural environment of Tehran for weathering studies and accelerated conditions were also performed for UV aging in UV chamber. At different time intervals, the changes in chemical structure of photosensitized polyethylene samples were studied by FTIR and compared to that of the control polyethylene films. Also the mechanical properties of photosensitized polyethylene films were determined in comparison with the control films by measuring the tensile strength and elongation at break after exposure to the natural environment and UV radiation. Results showed that the overall rate of degradation process is clearly dependent on the polyethylene composition, test conditions (natural or accelerated), season of the year, and the duration of the weathering of the samples.     

Role of Crosslinker on the Biodegradation Behavior of Starch/Polyvinylalcohol Blend Films

The effect of crosslinkers on the biodegradation behavior of starch/polyvinyl alcohol (PVA) blend films was investigated by weight loss study, Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Starch/PVA films were prepared by solution casting method and 5 weight% of four different crosslinking agents like epichlorohydrin, formaldehyde, zinc oxide and borax were used in four different sets to crosslink the films. These crosslinked starch/PVA films were biodegraded in compost. Weight loss study showed that crosslinking retarded the biodegradation of the films in the first 15?days, but after that, there was a significant increase in weight loss. The DSC analysis revealed that the consumption of starch and consequent rearrangement of the PVA molecules were distinctly different in the crosslinked films due to the effect of different crosslinking agents.     

Preparation and Biodegradation of Starch/Polycaprolactone Films

Starch granules were modified with trisodium trimetaphosphate (TSTP) and characterized by P³¹-NMR, FTIR and DSC. Seventy-micron films were prepared from modified starch and polycaprolactone blends by solvent casting technique. Three different types of films—PCL (100% polycaprolactone), MOD-ST/PCL (50% modified starch and 50% polycaprolactone blend) and NONMOD-ST/PCL (50% nonmodified starch and 50% polycaprolactone blends)—were prepared, and their thermal, mechanical, and morphologic properties were investigated to show the increased performance of PCL with the addition of starch and also the effect of modification. It was observed that with the addition of starch the Young's modulus of polycaprolactone was increased and became less ductile, whereas tensile strength and elongation at break values decreased. Biodegradation of these films was inspected under different aerobic environments with the presence of Pseudomonas putida, activated sludge, and compost. It was observed that whereas P. putida had almost no effect on degradation during 90 days, with the presence of activated sludge, considerable deformation of films was observed even in the first 7 days of degradation. In a compost environment, degradation was even faster, and all polymer films were broken into pieces within first 7 days of degradation and no film remained after 15 days.     

Investigation on Miscibility of Sodium Alginate/Pullulan Blends

Miscibility studies of Sodium alginate (NaAlg)/Pullulan have been carried out in different percentage of blend components. The ultrasonic velocity, viscosity, density and refractive index were measured at 30 and 40 °C. Further the blend films of NaAlg and Pullulan were prepared by solution casting method and characterized by differential scanning calorimetric (DSC), fourier transition infrared spectroscopic (FTIR), and scanning electron microscopic (SEM) methods. Using the viscosity data, interaction parameters were computed to determine the miscibility. The data suggest that the blend is miscible in the entire composition range. The change in temperature had no significant effect on the miscibility of NaAlg/Pullulan blends. The miscibility is confirmed by SEM, DSC, ultrasonic velocity, density, and refractive index methods. The specific interactions of hydrogen bonding type of the blends were investigated by FTIR.     

The Effect of Nanoclays on the Properties of PLLA-modified Polymers Part 1: Mechanical and Thermal Properties

Organically modified montmorillonite clays were incorporated at a 5% loading level into film grade of poly-L-lactic acid (PLLA) using a variety of masterbatches based on either semi-crystalline or amorphous poly-(lactic acid), as well as biodegradable aromatic aliphatic polyester. The PLLA masterbatches and compounded formulations were prepared using a twin screw compounding extruder, while the films were prepared using a single screw cast film extruder. The thermal and mechanical properties of the films were examined in order to determine the effect of the clay and different carriers on the polymer–clay interactions. In the optimal case, when a PLLA-based masterbatch was used, the tensile modulus increased by 30%, elongation increased by 40%, and the cold crystallization temperature decreased by 15 °C, compared to neat PLLA. The properties improvement of PLLA films containing nano clays demonstrated the possibility to extend the range of biodegradable film applications, especially in the field of packaging.     

Preparation and Characterization of Hydrogel Based on Poly(vinyl alcohol) Cross-Linked by Different Cross-Linkers Used to Dry Organic Solvents

Poly(vinyl alcohol) (PVA) hydrogels were chemically cross-linked with/without different cross-linkers such as glutaraldehyde and epichlorohydrin, in the presence of a catalyst, or activator (potassium hydroxide) to produce three types of hydrogels. The structures of PVA and the prepared gel types were determined by FTIR spectroscopy, the mechanical and thermal properties, of these hydrogels were examined. The effects of different pH values and temperatures on the swelling properties of the prepared gels were examined. From the obtained results, it was found that, the low concentration of the cross-linker produced hydrogel with moderate properties, but in absence of the cross-linker, the obtained hydrogel exhibited good properties and can be used as friendly environmentally moisture absorbents from the organic solvents. The insolubility and swelling properties of gels were tested in these solvents. The results indicated that these hydrogels can be used as moisture absorbents and solvent dryers.     

Active Bio-composite Sodium Alginate/Maltodextrin Packaging Films for Food Containing Azolla pinnata Leaves Extract as Natural Antioxidant

The aim of the current work was to produce sodium alginate (SA) maltodextrins (MD) based functional films incorporated with phenolic extract of Azolla pinnata leaves fern (AF) by solution molding technique. AF with different concentrations (0.8, 1.2 and 1.6% w/w) were integrated inside SA.MD films. The resulted films were characterized to investigate the surface structure by scanning electron microscope (SEM), thermal disposal by (DSC), crystallization by X-ray diffraction (XRD), potential interaction by (FT-IR) and some mechanical properties. The SEM micrographs indicated that the higher concentration (1.6%) of AF extract caused development of wrinkles on the surface of films. And as a result, there were a significant decrease of elongation at break (EB) and tensile strength properties of films to 55.01 and 58.42%, respectively. By continues addition of AF extract to SA.MD films, the film thickness increased from 0.124 to 0.181 mm, the scavenging and antimicrobial properties were enhanced by the attendance of ferulic acid, rutin, thiamine, tamarixetin, astragalin, quercetin, chlorogenic acid and epicatechin inside extracts. Furthermore, the films solubility, swelling degree and water vapor permeability were decreased to 13.08%, 26.41% and 1.662?×?10^??10 g H₂O/m s p.a. The resulted films could be utilized as composite packaging material for different food applications.

     

Action of soil microorganisms on PCL and PHBV blend and films

Poly(hydroxybutyrate-co-valerate) (PHBV) and poly(ε-caprolactone) (PCL) PCL/PHBV (4:1) blend films were prepared by melt-pressing. The biodegradation of the films in response to burial in soil for 30 days was investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The PHBV film was the most susceptible to microbial attack, since it was rapidly biodegraded via surface erosion in 15 days and completely degraded in 30 days. The PCL film also degraded but more slowly than PHBV. The degradation of the PCL/PHBV blend occurred in the PHBV phase, inducing changes in the PCL phases (interphase) and resulting in an increase of its crystalline fraction.     

Mechanical and Thermal Properties of PLLA/PCL Modified Clay Nanocomposites

Poly(l-lactic acid) (PLLA)/poly(caprolactone) (PCL) and two types of organoclay (OMMT) including a fatty amide and ocatdecylamine montmorillonite (FA-MMT and ODA-MMT) were employed to produce polymer nanocomposites by melt blending. Materials were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), elemental analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties were also investigated for these nanocomposites. The nanocomposites showed increasing mechanical properties and thermal stability. XRD results indicated that the materials formed nanocomposites. SEM morphology showed that increasing content of OMMT reduced the domain size of phase separated particles. TEM outcomes have confirmed the intercalated type of nanocomposite. Additionally, a solution casting process has been used to prepare these nanocomposites and characterized to compare these results with the above process.     

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.     

Synthesis of Segmented Polyurethane Based on Polymeric Soybean Oil Polyol and Poly (Ethylene Glycol)

Polyurethane (PUR) plastic sheets were prepared by reacting hydroxylated polymeric soybean oil (PSbOH) synthesized from autoxidized soybean oil with polyethylene glycol (PEG) in the presence of isophorone diisocyanate (IPDI). FTIR technique was used to identify of chemical reactions. These polyurethanes have different valuable properties, determined by their chemical composition. The effect of stoichiometric balance (i.e., PSbOH/PEG-2000/IPDI weight ratio) on the final properties was evaluated. The polyurethane plastic sheets with the PSbOH/PEG-2000/IPDI weight ratio 1.0/1.0/0.67 and 1.0/0.3/0.3 had excellent mechanical properties indicating elongation at break more than 200%. Increase in IPDI and decrease in PEG weight ratio cause the higher stress–strain value. The properties of the materials were measured by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), stress–strain measurements and FTIR technique.     

Biodegradation of LDPE/Modified Starch Blends Sterilized with Gamma Radiation

Blends of LDPE/modified starch were prepared, sterilized by gamma radiation and investigated with respect to their microbial degradation by a mixture of fungal strains in liquid medium after 90 days, was analyzed by carbon dioxide (CO₂) production (Sturm test). Biodegradation of blends was evaluated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction; mechanical testing, scanning electron microscopy (SEM). The biodegradation of LDPE/modified starch blends was attributed to microbiological attack, with alterations in the chemical structure of the blend with an increase in the carbonyl and vinyl indices and the appearance of new crystalline symmetry generating a crystalline domain not existing before in the blend and decrease in the mechanical properties.     

Effects of UV/Photo-Initiator Treatments on Enhancement of Crystallinity of Polylactide Films and Their Physicochemical Properties

Effects of UV/photo-initiator treatments on crystal formation and properties of polylactide (PLLA) films are investigated. Camphorquinone and riboflavin photo-initiator solutions in methanol are employed in the treatment of amorphous quenched PLLA films. Results from FTIR, ATR-FTIR, DSC, XRD, and SEM show evidence of crystalline domain formation dispersed throughout the film. ¹H NMR and GPC results suggest that the molecular weights of the polymer slightly decrease after the treatment. This indicates that the treatment leads to a diffusion of the photo-initiators molecules through the film matrix, resulting in a low degree of PLLA chain scissions, and formation of carboxylic acid and hydroxyl polar end groups. This, in turn, induces PLLA crystallization, which imposes profound effects on surface wettability and physical and mechanical properties of the samples. The process can be applied in optimizing properties of PLLA films with shorter treatment times, compared to other methods, which is suitable for use in various fields; especially those that require specific characteristics like biomedical, packaging and environmental applications.     

Characterization of Biodegradable Polymer Blends of Acetylated and Hydroxypropylated Sago Starch and Natural Rubber

Development of biodegradable polymers from absolute environmental friendly materials has attracted increasing research interest due to public awareness of waste disposal problems caused by low degradable conventional plastics. In this study, the potential of incorporating natural rubber latex (NRL) into chemically modified sago starch for the making biodegradable polymer blends was assessed. Native sago starch was acetylated and hydroxypropylated before gelatinization in preparing starch thermoplastic using glycerol. They were than casted with NRL into biopolymer films according to the ratios of 100.00/0.00, 99.75/1.25, 98.50/2.50, 95.00/5.00, 90.00/10.00 and 80.00/20.00 wt/wt, via solution spreading technique. Water absorption, thermal, mechanical, morphological and biodegradable properties of the product films were evaluated by differential scanning calorimetry (DSC), universal testing machine (UTM), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy. Results showed that acetylation promoted the incorporating behavior of NRL in sago starch by demonstrating a good adhesion characteristic and giving a uniform, homogenous micro-structured surface under SEM observation. However, the thin biopolymer films did not exhibit any remarkable trend in their DSC thermal profile and UTM mechanical properties. The occurrence of NRL suppressed water adsorption capacity and delayed the biodegradability of the biopolymer films in the natural environment. Despite the depletion in water adsorption capacity, all of the product films degraded 50 % within 12 weeks. This study concluded that biopolymers with desirable properties could be formulated by choosing an appropriate casting ratio of the sago starch to NRL with suitable chemical substitution modes.     

The Effects of Additives on the Biodegradation of Polycaprolactone Composites

Because environmental pollution caused by plastic waste is a major problem investigations concerning biodegradable packaging are important and required. In this study, the biodegradation of PCL composite films with organic (glycerol monooleate and oleic acid) and inorganic additives (organo nano clay) was investigated to understand which additive and the amount of additive was more effective for biodegradation. The relationship between the degree of crystallinity and the effect of additives on the biodegradability of polycaprolactone (PCL) was examined. PCL composite films were prepared using organo nano clay (0.1–0.4–1–3 wt%) and oleic acid (1–3–5 wt%) or GMO (1–3–5 wt%). The 35 films prepared with PCL (P), clay (C), oleic acid (O), or glycerol monooleate (G) are coded as P_C#wt%_O (or G)#wt%. The composite films, P_C0.4_O5 contains 0.4 wt% clay and 5 wt% oleic acid and the P_C3_G1 contains 3 wt% clay and 1 wt% glycerol monooleate. The biodegradation of PCL films in simulated soil was studied for 36 months. The films were periodically removed from the simulated soil and film thicknesses, weight losses, visual changes, crystal structures, and a functional group analyses were performed. PCL composite films are separated into three groups, depending on degradation time, (1) films that degraded before 8 months (fast degradation), (2) films that degraded around 24 months (similar to neat PCL), and (3) films that take longer to degrade (slow degradation). The films in the first group are PCL films with 1 and 3 wt% clay additive and they begin to biodegrade at the 5th month. However, a composite film of PCL with only 0.4 wt% clay and 5 wt% GMO addition has the shortest degradation time and degraded in 5 months. The films in the last group are; P_G3, P_G5, P_C0.1, P_C0.1_O1, and P_C0.1_O5 and they took around 30 months for biodegradation. It was observed that increasing the organo nanoclay additive increases the biodegradability by disrupting the crystal structure and causing a defective crystal formation. The addition of GMO with organo nano clay also accelerates biodegradation. The addition of organo nano clay in an amount as small as 0.1 wt% acts as the nucleating agent, increases the degree of crystallinity of the PCL composites, and slows the biodegradation period by increasing the time.