Blown Film Extrusion Research Articles

The Eff ect of Pregelatinized Starch on the Properties of Poly (Vinyl Alcohol) Film for the Water-Soluble Laundry Bag

The goal of this study was to develop pregelatinized starch (P-St) and polyvinyl alcohol (PVOH) fi lms as water-soluble laundry plastic bags to avoid having contact with COVID-19 infected clothes by extrusion method. The effects of pregelatinized starch (P-St) content on the properties of polyvinyl alcohol (PVOH) fi lms were examined. PVOH and P-St blend were compounded by twin- screw extruder with various P-St content of 0, 10, 20, 30, and 40% by weight with fi xed glycerol content of 20 phr. The blend fi lms were produced by blown fi lm extrusion. The chemical structure, thermal properties, water-solubility, mechanical properties, and the cross-sections morphological properties of PVOH/G/P-St were characterized. As a result, the formation of intermolecular interactions between PVOH, glycerol and P-St was confi rmed by FTIR. Moreover, the addition of P-St on PVOH could reduce the thermal stability due to the content of P-St with amylose, a substance of amorphous structure, affecting the chains fl exibility of PVOH/G/P-St. From the differential scanning calorimeter result, the glass transition temperature was increased with the increment of P-St content because the chains entanglement between PVOH and P-St had affected the reduction in crystallinity and led to the decrement of the melting temperature. Furthermore, the water solubility would strongly be dependent on the percentage of the gelatinized starch (%GS). The solubility decreased as the percentage of the GS increased. In addition, PVOH with 20% of P-St fi lm possessed the highest value in tensile strength and modulus, and the particles of P-St have a good distribution in PVOH/G indicating to stronger interaction of P-St and PVOH/G.

Development and characterization of ester modified endospermic guar gum/polyvinyl alcohol (PVA) blown film: Approach towards greener packaging

With growing environmental concerns, the biopolymer-based film provides a suitable substitute for sustainable packaging applications. In this article, guar gum based bioplastic films were prepared by taking various ratios of Polyvinyl Alcohol with guar gum along with Octenyl succinic anhydride (OSA) and plasticizer followed by blown film extrusion process to encourage industrial-scale production. The films were prepared with the utilization of pre-treated guar gum powder, Polyvinyl alcohol and OSA at various weight ratios with the help of blown film extruder . The temperature zone of the extrusion machine was maintained from feeding zone to metering zone with optimized processing parameters. After the production of film, characterization studies such as mechanical, thermal and morphological properties were analyzed. The tensile strength of films was gradually improved in the machine direction due to modified OSA in GG/PVA having good tear resistance whereas, the percentage of failure is less during dart impact test. The thermal characterization reveals the transition temperature exceeding due to modification. The morphological analysis also supports better compatibility between GG with PVA with improved chemical interaction, as established by FTIR analysis. The contact angle test was carried out to measure the hydrophobicity, which suggest improved characteristics suitable for packaging application. • Esterified GG/PVA-based films were prepared with improved hydrophobicity. • Morphological analysis showed improved compatibility and interaction between PVA and guargum. • Film-forming of GG/PVA-based films provides suitability for various packaging applications. • Traditional extrusion process suit the market demand in the field of biopolymer .

Feasibility of production starch/poly(butylene adipate‐co‐terephthalate) biodegradable materials with microalgal biomass by blown film extrusion

AbstractThis research aimed to develop blends of corn starch and poly(butylene adipate‐co‐terephthalate) (PBAT) films by blown film extrusion with the addition of biomass of Chlorella pyrenoidosa (CP). Two ultrasound tracts disrupted CP biomass: ultrasound bath and ultrasonic probe. The influence of CP biomass and disrupted CP biomass on the physical, mechanical, barrier, structural, and thermal properties of starch/PBAT films was evaluated. The film with higher content (5.0%) of CP biomass showed better values in tensile strength (TS) (4.37 MPa) and elongation (88.43%), and lower water vapor permeability (WVP) (5.19 × 10−11 g m−1 s−1 Pa−1) than the film incorporated with disrupted CP biomass. The ultrasound treatment applied to the cell disruption of the microalgae did not present improvements in the properties of the films. In this context, the cell disruption of CP biomass by ultrasound for incorporation into biodegradable films was not feasible. However, it was possible to produce starch/PBAT/microalgae films with potential application as food packaging due to natural bio‐pigmentation's protection system against ultraviolet light.Practical ApplicationsFilms produced by blown extrusion from starch, PBAT, and CP microalgae biomass have the technological potential to be used as packaging for food products. Starch and PBAT blends are widely studied. The incorporation of PBAT is necessary to confer adequate mechanical properties to the extruded material. The plastic industries already use the blown extrusion method, allowing biodegradable packaging development on an industrial scale.

Use of orange juice processing waste to produce films using blown film extrusion for food packaging

Orange peel (OP) is a by-product from citrus juicing that is wasted. Conversion of this waste into plastic filler can help reduce environmental problems. OP has been incorporated into plastics to form biocomposites using compression molding, injection molding, and casting. However, blown film extrusion, the most common manufacturing process for plastic films has not been investigated yet. The aims of this study were: (1) to produce linear low density polyethylene (LLDPE)/OP films using blown film extrusion, (2) to determine the maximum OP amount that can be used to replace plastic through blown film production, and (3) to assess the effect of OP amount on film morphology and properties. LLDPE/OP masterbatch pellets were produced and combined with neat LLDPE using specific processing parameters determined to produce blown LLDPE/OP composite films differing in OP content (5, 10, 11.5, and 12.5%). The morphology, thickness, and mechanical, barrier, optical and thermal properties of the blown composite films and neat films were compared. The results show that LLDPE/OP films containing up to 11.5% OP can be produced through blown film extrusion. These films have similar (p > 0.05) water barrier, crystallinity, and melting temperature, but lower tensile strength and elongation at break than neat LLDPE films. OP loading enhanced the UV and visible light blocking capacity of the films. This study revealed that blown LLDPE/OP films are suitable for food packaging.

Mono and multilayer active films containing green tea to extend food shelf life

An active packaging film made of one and two-layers structure based on low-density polyethylene (LDPE) was produced with the incorporation of green tea extract (GTE) at different amounts by blown film extrusion. Film structure, optical, mechanical, antioxidant and barrier properties were characterized. The films revealed homogeneous film surface, the presence of GTE increases the tensile properties, improves friction coefficient and reduces LDPE films transparency. Moreover, the antioxidant capacity and barrier properties (water and oxygen) were enhanced, even at low concentrations. This study demonstrates the benefits of GTE incorporation into LDPE matrix, mainly in coextruded films, and its potential to develop an active and sustainable food packaging film at industrial scale.

Migration, aggregations and thermal degradation behaviors of TiO2 and ZnO incorporated PBAT/TPS nanocomposite blown films

Metal oxides including titanium dioxide (TiO2) and zinc oxide (ZnO) enhanced the properties and functional performance of biodegradable plastic food packaging. Effects of TiO2 and ZnO nanofillers (1-5%) on bioplastic packaging microstructural changes were investigated for infrared absorption, thermal stability and migration behavior in distilled water, 10% ethanol and 3% acetic acid. Nanoparticles were compounded with thermoplastic starch (TPS) before blending with polybutylene adipate-co-terephthalate (PBAT), and converted into nanocomposite films via blown-film extrusion. Microstructural analysis indicated that addition of TiO2 and ZnO enhanced disruption of starch granules, increasing the amorphous starch portion. Energy dispersive X-ray analysis (EDX) exhibited higher aggregations of TiO2 particles than ZnO, coincident with higher degree of hydrogen bonding between ZnO and TPS phase. Strong interaction between ZnO and polymers also modified degradation temperatures (Td) of both PBAT and TPS phase in PBAT/TPS blend films. TiO2 gave identical Td but higher residual mass depending on nanocomposite amounts that modified the amorphous-crystalline fraction. Films with ZnO had higher migration levels, particularly in acid simulant due to high dissolution of ZnO particles, analyzed by inductively coupled plasma mass spectrometry. Release of titanium was strongly dependent on simulant types, showing maximum at 3-4% TiO2 followed by a sharp drop at higher TiO2 levels. Films containing ZnO showed higher migration levels, indicating that films containing TiO2 were more inert. Migration levels of titanium and zinc metals from TiO2 and ZnO incorporated PBAT/TPS blown films were influenced by alteration of the matrix structure due to simulant penetrations, interaction and adhesion forces between metals and polymers and favorable dissolution of the metal into simulants. Interaction between simulant-polymer and simulant-metal oxide particles further modified film matrices and enhanced release. The films showed promise for use in aqueous surroundings for food applications.

Effect of Local Heat Pipe Cooling on Throughput Distribution and Thermal Homogeneity in a Binary Melt Pre-Distributor for Polyolefin Extrusion

In polymer blown film extrusion, inhomogeneous die temperature distributions lead to an inhomogeneous temperature and cause film thickness variations. To avoid an inhomogeneous film thickness and to achieve good film qualities, thermal homogenisation of the melt is necessary. Therefore, a new approach for cooling hot spots with heat pipes is investigated. CFD Simulations in OpenFOAM show that heat pipes can be used to influence melt temperatures locally in the places in which a temperature reduction is required. Since the outlets interact in a pre-distribution die, one heat pipe is not sufficient to homogenise the temperature at every outlet to similar temperatures. Two heat pipes show much better results with lower average temperature deviations between the distributor outlets. In order to equalise the temperature at all outlets, at least one heat pipe per outlet will be required.

Property improvement of processed PLA/PBAT using chain extenders

The polymer blend of poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT), commercially named Ecovio, is a biodegradable plastic with a high level of strength and toughness. Despite the development of biodegradable plastics with improved characteristics and greater applicability, their cost remains prohibitively high preventing their widespread use. One approach to reducing production costs is recycling manufactured waste plastics. However, in this process, the properties of plastic are typically changed due to chain scissions during thermal reprocessing. Using an additive such as a chain extender is thought to reconnect cleaved polymer chains. Therefore, the purpose of this research is to investigate the influences of two chain extenders, multifunctional epoxide and multifunctional imide, on the mechanical properties and thermal properties as well as the melt flow rate of Ecovio. Materials were processed and blended using a twin-screw extruder and formed into film samples via the blow film extrusion process. The findings revealed that the addition of chain extenders resulted in a higher viscosity of Ecovio. In the thermal properties test, it was found that the use of chain extenders resulted in shifts in the glass transition, crystallization, melting temperature, and thermal stability of Ecovio. Finally, the result of mechanical properties test illustrated that Young’s modulus and tensile strength of thermal processed Ecovio were changed and improved by blending with virgin Ecovio and chain extenders.

​Effect of Cassava Starch on LDPE as Biodegradable Film and its Physical and Mechanical Properties

Background: Biodegradable plastics are made from starch extracted from renewable biomass. Approximately 50% of the biodegradable plastics used commercially are prepared from starch. The research was undertaken to develop biodegradable film from blend of LDPE and Cassava starch at different proportions and to study the Physical and Mechanical properties. Methods: Biodegradable film was prepared by Blown film extrusion method using LDPE, cassava starch adding glycerol, talc powder and urea (T0, T1, T2, T3 and T4) at different proportions. The effects of plasticizer (glycerol) and different proportions of cassava starch on the film properties were determined by the standard methods. Result: The developed biodegradable film had a tensile strength ranging from 6.68-8.42 MPa. The film thickness from 0.17 to 0.80 mm, transparency from 0.55 to 2.07%, water absorption from 0.007 to 0.067% and moisture permeability from 0.59 to 14.08%.

Physicochemical characterization and biodegradation test of oxo-degradable linear low-density polyethylene films subjected to gamma irradiation and accelerated weathering

LLDPE is widely used as a packaging material for different purposes, mainly in food packaging. However, the accumulation of this material in the environment contributes to plastic pollution, generates environmental problems, and has harmful effects on biodiversity. In this study, 12 types of LLDPE films were formulated with a pro-oxidant additive (PA) (0 and 1% w/w) and thermoplastic starch (TPS) (0, 10, 20, 30, 40, and 50% w/w) by blown-film extrusion process. Formulation F12 showed similar color parameters and mechanical properties to the control film (F1); it was the selected formulation (SF) to be subjected to gamma irradiation (30 kGy) and accelerated weathering (25, 50, and 100 h). The tensile strength and elongation at break decreased after gamma irradiation and 25 h of accelerated weathering. In contrast, the modulus of the irradiated SF showed a higher increase than non-irradiated after 50 and 100 h of accelerated weathering. The structural analysis indicated scission and formation of carbonyl groups in the main LLDPE chain. The results of DSC demonstrated a progressive increase in the crystallinity of the SF (higher in irradiated samples), reaching around 99% in sample SF30kGy100 h. The biodegradation test revealed that the SF and SF25h samples reached 32.7% and 39.5%, respectively, after 180 days of incubation. However, the SF30kGy25 h sample showed a level of biodegradation of 16%. The biodegradability of SF increased with 25 h of accelerated weathering, while it decreased with the combined effect of treatments.

Process-Induced Morphology of Poly(Butylene Adipate Terephthalate)/Poly(Lactic Acid) Blown Extrusion Films Modified with Chain-Extending Cross-Linkers.

Process-induced changes in the morphology of biodegradable polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) blends modified with various multifunctional chain-extending cross-linkers (CECLs) are presented. The morphology of unmodified and modified films produced with blown film extrusion is examined in an extrusion direction (ED) and a transverse direction (TD). While FTIR analysis showed only small peak shifts indicating that the CECLs modify the molecular weight of the PBAT/PLA blend, SEM investigations of the fracture surfaces of blown extrusion films revealed their significant effect on the morphology formed during the processing. Due to the combined shear and elongation deformation during blown film extrusion, rather spherical PLA islands were partly transformed into long fibrils, which tended to decay to chains of elliptical islands if cooled slowly. The CECL introduction into the blend changed the thickness of the PLA fibrils, modified the interface adhesion, and altered the deformation behavior of the PBAT matrix from brittle to ductile. The results proved that CECLs react selectively with PBAT, PLA, and their interface. Furthermore, the reactions of CECLs with PBAT/PLA induced by the processing depended on the deformation directions (ED and TD), thus resulting in further non-uniformities of blown extrusion films.

Effect of different modified starches on physical, morphological, thermomechanical, barrier and biodegradation properties of cassava starch and polybutylene adipate terephthalate blend film

Modified starch enhanced the compatibility and modified the properties of thermoplastic starch (TPS) and polybutylene adipate terephthalate (PBAT) biodegradable films. Native (NS), acetylated (AS), octenyl-succinated (OS) and hydroxypropylated (HS) starch were compounded with PBAT via extrusion. PBAT/TPS (40/60 and 50/50 ratios) blend films were produced by blown-film extrusion and characterized for morphology, crystallinity, thermomechanical properties, mechanical and barrier properties. Topographic and scanning electron micrographs showed diverse dispersion and morphologies of starch granules depending on hydrophobicity that governed interface exposure between incompatible polymers. Hydrophilic starch formed phase separated fibrous-like networks entangled in PBAT at higher TPS ratios. Hydrophobic OS starch improved compatibility and interaction with PBAT, greatly modifying mechanical and barrier properties (82–89%). TPS slightly increased α-relaxation temperature and modified arrangements of aromatic structures in PBAT, involving C-H and C-O bonding, subsequently influencing crystallinity of PBAT and the starch phase. Biodegradation of the blend films was dependent on hydrophilicity of starch, giving the fastest degradation in NS and HS. Findings indicated that hydrophobically modified starch improved compatibility with PBAT for biodegradable packaging, while film properties were highly dependent on the morphology of blend matrices.

Blown film extrusion of PBAT/TPS/ZnO nanocomposites for shelf-life extension of meat packaging

Biodegradable polymers typically have inferior barrier properties compared to petroleum-based nonbiodegradable plastic. The addition of zinc oxide nanoparticles may enhance the functional properties of biodegradable packaging and extends the shelf life of packaged foods. Polybutylene adipate-co-terephthalate (PBAT) and thermoplastic starch (TPS) blended ZnO (1–5%) nanocomposite films were developed via blown extrusion for functional active meat packaging. The nanocomposite film morphology showed agglomeration of the nanoparticles, causing poor mechanical properties. Nanovoids formed at the interface between the polymer and nanoparticles, increasing permeability. Dispersion of ZnO nanofillers modified CO and C-O ester bonding in PBAT and increased hydrogen bonding with TPS. The interaction between ZnO and polymers increased the dispersion and reduced the agglomeration of nanoparticles. The highest ZnO content at 5% resulted in a stronger interaction between ZnO and TPS due to increased amorphous starch content, which improved homogeneous dispersion within the matrices, reducing nanoparticle size. The ZnO nanocomposite films reduced lipid oxidation and delayed microbial growth, resulting in a lower total viable count, lactic acid bacteria and yeast and mold in packaged pork meat. Higher ZnO concentrations from 3% showed microbial inhibitory effects. The growth of microorganisms was controlled by residual oxygen, morphology of the films and nanoparticle characteristics. The nanocomposite films effectively extended the shelf life by more than 3 days under refrigerated conditions.

Ethylene vinyl acetate/low-density polyethylene/oyster shell powder composite films: Preparation, characterization, and antimicrobial properties for biomedical applications

BackgroundTo maintain the biocompatibility, the addition of natural antimicrobial compounds to the conventional polymeric materials is being heavily investigated to serve antimicrobial single use products. MethodsThis study focus on the fabrication of ethylene-vinyl acetate/low-density polyethylene/calcined oyster shell powder (OSP) composite films via blown film extrusion method and study of its physicochemical properties including antimicrobial properties for biomedical applications. To improve the miscibility, OSP dispersion, and mechanical properties of the composite films, polyethylene graft maleic anhydride (PEgMA) was further introduced as a compatibilizer. The prepared composites films were characterized by Fourier-transform infrared spectroscopy in attenuated total reflection mode (ATR-FTIR), solid-state 13C nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermal properties (TGA and DSC), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), mechanical properties, and water resistance. Moreover, antimicrobial properties were evaluated for the selected samples. Significant findingsOSP imparts the composite films with antimicrobial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, in addition to remarkably enhancing the thermal stability of the resulting material. From the FESEM analysis, the morphologies of the composite films showed homogenous in the case of PEgMA (1 wt%) and OSP (3 wt%) composite film due to the low interfacial tension and high chemical tendencies in the composite matrix.

Utilization of lignin extracted from Thai ago-waste as UV-blocking agent for BG-lignin/PLA composite films

The improving properties of poly(lactic acid), PLA, by utilizing natural resources attracted great intrigue to make such a green composite material that can be used as a commercial product in human life [1]. Lignin is one of biopolymer that can be used as bio-based filler and multifunctional bio-additive in a polymer composite. The most exciting properties of lignin that can be provided in a polymer composite is UV absorption and anti-oxidation [2]. In this current study, organosolv lignin extracted from sugarcane bagasse (BG-lignin) was utilized as multifunctional bio-additive in PLA for improving the UV absorption. The physicochemical and thermal properties of BG-lignin were determined using several techniques including SEM, GPC, quantitative 31P NMR, and DSC. BG-lignin at different loading contents (0.1, 0.2, 0.5, and 1 wt.%) was mixed with PLA via melt-extrusion. The attained compounds were converted to composite films via blown film extrusion. With the 0.5 wt.% loading content, the PLA composite films (0.5BG-lignin/PLA) absorbed almost all UV radiation which exhibits almost 70% blocking of UVB. The onset oxidation temperature of the PLA/0.5BG composite film increased by 34% as compared to that of the neat PLA film. Adding of BG-lignin enhanced tensile strength and Young’s modulus but did not favour to elongation at break.

Morphology and permeability of bio-based poly(butylene adipate-co-terephthalate) (PBAT), poly(butylene succinate) (PBS) and linear low-density polyethylene (LLDPE) blend films control shelf-life of packaged bread

Poly(butylene adipate-co-terephthalate) (PBAT), poly(butylene succinate) (PBS) and linear low-density polyethylene (LLDPE) were blended to produce bio-based packaging via blown-film extrusion. Blend ratios modified morphology, crystallinity and relaxation temperatures (T α ) of the films. Binary mixtures caused phase separation and non-homogeneous fibrous microstructures of immiscible polymers. Bio-based blend films containing LLDPE (LLDPE/PBAT and LLDPE/PBS) gave less homogeneous structures than PBAT/PBS films. The formation of oriented fibrous networks subsequently controlled mechanical and barrier properties of the blend films. LLDPE blending modified C=O carbonyl groups in PBAT and PBS, forming voids in topographic images indicating incompatibility. PBAT and PBS blends showed good compatibility and adhesion of polymer interface, causing smooth and compact structures with minimal surface roughness. Incorporation of PBAT and PBS sharply reduced crystallinity of LLDPE/PBAT and LLDPE/PBS films. LLDPE/PBAT blends had lower T α than neat PBAT and LLDPE, while T α of PBAT/PBS blends proportionally decreased at increasing PBS which indicated diverse polymer miscibility and molecular mobility. Water vapor permeability (WVP) and oxygen permeability (OP) fitted with polynomial and exponential equations, respectively and depended on blend ratios. Films containing higher PBS had combined higher WVP and lower OP, delaying fungal growth in packaged bread due to dehydration. Ratios of PBAT, PBS and LLDPE blend films clearly affected mold growth and crumb hardness during storage. Regardless of film components, the firmness of bread crumbs increased linearly with package WVP. Conversely, mold growth had insignificant correlation with OP. Moisture loss from bread crumbs due to high WVP showed dominant effects on microbial growth. Blending PBAT and PBS modified the morphology and permeability of bio-based films and increased the shelf-life of packaged bread. • Systematic investigations for packaging properties in bio-based PBAT/PBS/PE blends. • FTIR intensity ratios effectively monitor bonding and morphology modifications. • H 2 O and O 2 permeability in PBAT/PBS/PE blends fitted to cubic and exponential model. • Hardness of packaged bread linearly increased with water vapor permeability. • Water vapor permeability majorly affected mold growth and increasing crumb hardness.

Development and characterization of PLA and Cassava starch‐based novel biodegradable film used for food packaging application

Pure starch like PLA is an outstanding substitute to prepare packaging film, nevertheless, because of its greater hydrophilicity, mixing it with other starch become essential. Cassava is a root vegetable that is an excellent source of starch, and it can be used to prepare bio-based packaging materials. The packaging films were developed by blown film extrusion method using 10% and 20% cassava starch, blended with PLA. The water vapor barrier property, and other physico-chemical properties of the packaging films were determined, and it was observed that the film characteristics of PLA and Cassava starch up to 20%, were equally suitable for packaging application to virgin PLA-based film. The biodegradable film developed for MA packaging, had a potential to retain the quality attributes of capsicum up to 12 and 24 days at 25°C and 8°C, respectively as compared to the shelf-life of unpackaged capsicum viz. 4 and 9 days at respective temperatures. Novelty impact statement The film characteristics like haze %, tensile strength, OTR and WVTR parameters for PLA, and 20% cassava starch were found to be 89.68%, 25.16 MPa, 123.92 cc/m2/day, and 217 gm/m2/day, respectively. The physico-chemical characteristics of the developed packaging films were found to be better as compared to other starch and PLA blended film. The outcomes of biodegradable film-based MA packaging were compared to a non-biodegradable film-based MA packaging of capsicum, it was observed that the application of biodegradable film offers a new alternative over the non-biodegradable polymeric film for MA packaging of fresh produce without compromising its quality.

Electron Beam-Mediated Cross-Linking of Blown Film-Extruded Biodegradable PGA/PBAT Blends toward High Toughness and Low Oxygen Permeation

Due to its high crystallinity, tailored compostability, and superior barrier performance, poly(glycolic acid) (PGA) has great potential as a substitute for current single-use plastics used in food packaging applications and with a lower carbon footprint. However, its susceptibility to hydrolysis and mechanical brittleness hinders its direct suitability in packaging. In this work, we circumvent this limitation by first blending PGA with a thermoplastic polyester, poly(butylene adipate-co-terephthalate) (PBAT), and a glycidyl cross-linker via industrial-scale twin-screw extrusion and then converting to a film by blown film extrusion. The surface of the films was then chemically cross-linked using electron beam treatment (EBT) to impart excellent barrier properties. Here, the electron beam plays a dual role. Firstly, it cross-links the surface of the films and improves the oxygen and moisture barrier performance, both improved due to blending with PBAT. Second, it does not compromise the toughness or extension at break of the polymer blend, both desirable for flexible packaging applications. A dosage of 250 kGy EBT resulted in the film having an oxygen barrier permeation of 57.0–59.8 cm3 mm m–2 24 h–1 atm–1 and a water vapor permeation of 26.8 g m–2 24 h–1 while maintaining a high toughness of 75 MPa. At dosages higher than 300 kGy, inhomogeneities formed on the surface of the films and some degradation in the mechanical properties of the films is observed. This work highlights the possibility of deriving superior biopolymer barrier performance while retaining the mechanical properties required for food packaging using a combination of blending and electron beam treatment, both scalable processes.

Thermoplastic starch blown films functionalized by plasticized nitrite blended with PBAT for superior oxygen barrier and active biodegradable meat packaging

Functional bioplastic packaging was produced from thermoplastic starch (TPS) with nitrite (1–5%) and polybutylene adipate terephthalate (PBAT) (PBAT/TPS at 30/70 and 40/60) via blown-film extrusion. TPS-nitrite interaction increased thermal destabilization and decreased α-relaxation temperature of TPS phase, indicating improved plasticization and disruption of starch granules. Nitrite modified C=O bonding of PBAT and improved compatibility with TPS networks, resulting in compact microstructures that reduced oxygen and water vapor permeability. Films containing nitrite showed up to 39.7% decrease (p≤0.05) in mechanical properties while effectively improving and stabilizing redness of vacuum-packaged pork during storage for 12 days. Nitrite release led to up to 0.66 ppm residual nitrite, which corresponded to formation of nitrosyl myoglobin (3.4–9.6 ppm), and effectively reduced total viable count, lactic acid bacteria and yeast and molds (p≤0.05). Stabilized lipid components also increased with increasing nitrite. Novel nitrite-containing biodegradable film enhanced functional properties and retained quality of packaged meat.

Plasticized hydroxypropyl cassava starch blended PBAT for improved clarity blown films: Morphology and properties

Plasticized hydroxypropyl cassava thermoplastic starch (TPS) with glycerol was blended with polybutylene adipate terephthalate (PBAT) via blown-film extrusion. Effects of PBAT/TPS ratios (60/40 and 50/50) and degrees of substitution (DS) for hydroxypropyl groups in TPS on film properties were investigated. All PBAT/TPS blend films were determined for morphology, thermal stability, thermomechanical, mechanical and barrier properties. Higher DS increased film clarity and glossy surface, improved compatibility between PBAT and TPS, reduced crystallinity and enhanced exposure of hydroxyl groups and hydrogen-bonding of the films. Blending caused phase separation with dispersed starch granules in continuous PBAT matrices, giving high surface roughness. Increased TPS and DS facilitated formation of co-continuous structures and miscibility, improving elongation by approximately 210%. Different DS modified microstructure and hydrophilicity of PBAT/TPS films which consequently reduced water vapor permeability by 34%. Modified DS in hydroxypropyl starch efficiently improved clarity, mechanical and barrier properties of bioplastic packaging.