Polymers

Research

16 pages, 3136 KiB

Open AccessArticle

Polyhydroxyalkanoates-Based Nanoparticles as Essential Oil Carriers

by Iolanda Corrado, Rocco Di Girolamo, Carlos Regalado-González and Cinzia Pezzella

Polymers 2022, 14(1), 166; https://doi.org/10.3390/polym14010166 - 1 Jan 2022

Cited by 22 | Viewed by 3027

Plant-derived essential oils (EOs) represent a green alternative to conventional antimicrobial agents in food preservation. Due to their volatility and instability, their application is dependent on the development of efficient encapsulation strategies allowing their protection and release control. Encapsulation in Polyhydroxyalkanoate (PHA)-based nanoparticles [...] Read more.

Plant-derived essential oils (EOs) represent a green alternative to conventional antimicrobial agents in food preservation. Due to their volatility and instability, their application is dependent on the development of efficient encapsulation strategies allowing their protection and release control. Encapsulation in Polyhydroxyalkanoate (PHA)-based nanoparticles (NPs) addresses this challenge, providing a biodegradable and biobased material whose delivery properties can be tuned by varying polymer composition. In this work, EO from Mexican oregano was efficiently encapsulated in Polyhydroxybutyrate (PHB) and Poly-3-hydroxybutyrate-co-hydroxyhexanoate (PHB-HHx)-based NPs by solvent evaporation technique achieving high encapsulation efficiency, (>60%) and loading capacity, (about 50%). The obtained NPs displayed a regular distribution with a size range of 150–210 nm. In vitro release studies in food simulant media were fitted with the Korsmeyer–Peppas model, indicating diffusion as the main factor controlling the release. The cumulative release was affected by the polymer composition, possibly related to the more amorphous nature of the copolymer, as confirmed by WAXS and DSC analyses. Both the EO-loaded nanosystems displayed antimicrobial activity against Micrococcus luteus, with PHB-HHx-based NPs being even more effective than the pure EO. The results open the way to the effective exploitation of the developed nanosystems in active packaging. Full article

(This article belongs to the Special Issue Biopolymers and Bioplastics)

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11 pages, 2531 KiB

Open AccessArticle

Development of Quebracho (Schinopsis balansae) Tannin-Based Thermoset Resins

by Emanuele Cesprini, Primož Šket, Valerio Causin, Michela Zanetti and Gianluca Tondi

Polymers 2021, 13(24), 4412; https://doi.org/10.3390/polym13244412 - 16 Dec 2021

Cited by 9 | Viewed by 3404

Abstract

One of the major challenges currently in the field of material science is finding natural alternatives to the high-performing plastics developed in the last century. Consumers trust synthetic products for their excellent properties, but they are becoming aware of their impact on the [...] Read more.

One of the major challenges currently in the field of material science is finding natural alternatives to the high-performing plastics developed in the last century. Consumers trust synthetic products for their excellent properties, but they are becoming aware of their impact on the planet. One of the most attractive precursors for natural polymers is tannin extracts and in particular condensed tannins. Quebracho (Schinopsis balansae) extract is one of the few industrially available flavonoids and can be exploited as a building block for thermoset resins due to its phenol-like reactivity. The aim of this study was to systematically investigate different hardeners and evaluate the water resistance, thermal behavior, and chemical structure of the quebracho tannin-based polymers in order to understand their suitability as adhesives. It was observed that around 80% of the extract is resistant to leaching when 5% of formaldehyde or hexamine or 10% of glyoxal or furfural are added. Additionally, furfuryl alcohol guarantees high leaching resistance, but only at higher proportions (20%). The quebracho-based formulations showed specific thermal behavior during hardening and higher degradation resistance than the extract. Finally, these polymers undergo similar chemistry to those of mimosa, with exclusive reactivity of the A-ring of the flavonoid. Full article

(This article belongs to the Special Issue Biopolymers and Bioplastics)

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13 pages, 4558 KiB

Open AccessArticle

Transparent Cellulose-Based Films Prepared from Used Disposable Paper Cups via an Ionic Liquid

by Zhen Xu, Qiwen Zhou, Lixiang Wang, Guangmei Xia, Xingxiang Ji, Jinming Zhang, Jun Zhang, Haq Nawaz, Jie Wang and Jianfeng Peng

Polymers 2021, 13(23), 4209; https://doi.org/10.3390/polym13234209 - 1 Dec 2021

Cited by 11 | Viewed by 4258

Abstract

Paper cups are widely employed in daily life with many advantages, but most of the used paper cups are incinerated or landfilled, due to the great challenge of separating the thin inner polyethylene (PE) coating, causing the waste of energy and the pollution [...] Read more.

Paper cups are widely employed in daily life with many advantages, but most of the used paper cups are incinerated or landfilled, due to the great challenge of separating the thin inner polyethylene (PE) coating, causing the waste of energy and the pollution of our environment. Therefore, recycling and converting the used paper cups into high-value materials is meaningful and important. In this work, transparent cellulose-based films were successfully prepared from the used paper cups via 1-allyl-3-methylimidazolium chloride ionic liquid after simple pretreatment. Additionally, the difference in properties and structures of cellulose-based films regenerated in different coagulation baths (water or ethanol) was also explored. It was found that the cellulose-based film possessed good thermal property and displayed better hydrophobicity than the traditional pure cellulose film. Moreover, they also demonstrated good mechanical property and the tensile strength of cellulose-based film regenerated in water can reach 31.5 Mpa, higher than those of cellulose-based film regenerated in ethanol (25.5 Mpa) and non-degradable polyethylene film (9–12 MPa), indicating their great potential as the packaging materials. Consequently, valorization of the low cost used paper cups and preparation of high-valve cellulose-based films were realized simultaneously by a facile and green process. Full article

(This article belongs to the Special Issue Biopolymers and Bioplastics)

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20 pages, 6853 KiB

Open AccessArticle

Dynamic Mechanical Analysis and Thermal Expansion of Lignin-Based Biopolymers

by Simona-Nicoleta Mazurchevici, Dorin Vaideanu, Doreen Rapp, Cristian-Dragos Varganici, Constantin Cărăușu, Mihai Boca and Dumitru Nedelcu

Polymers 2021, 13(17), 2953; https://doi.org/10.3390/polym13172953 - 31 Aug 2021

Cited by 7 | Viewed by 3432

Abstract

Biodegradable materials investigation has become a necessity and a direction for many researchers worldwide. The main goal is to find sustainable alternatives which gradually replace plastics based on fossil resources from the market, because they are very harmful to the environment and to [...] Read more.

Biodegradable materials investigation has become a necessity and a direction for many researchers worldwide. The main goal is to find sustainable alternatives which gradually replace plastics based on fossil resources from the market, because they are very harmful to the environment and to overall quality of life. In order to get to the stage of obtaining different functional parts from biodegradable materials, it is necessary to study their properties. Taking into account these shortcomings, this paper aims at the mechanical characterization (DMA—Dynamic Mechanical Analysis) and thermal degradation (thermogravimetric analysis (TGA)) of lignin-based biopolymers: Arboform LV3 Nature^®, Arboblend^® V2 Nature, and Arbofill^® Fichte Arboform^® LV3 Nature reinforced with aramid fibers. The tested samples were obtained by using the most common fabrication technique for polymers—injection molding. The obtained results for the DMA analysis showed separate polymeric-specific regions for each material and, based on the tanδ values between (0.37–0.54), a series of plastics could be proposed for replacement. The mechano-dynamic behavior could be correlated with the thermal expansion of biopolymers for temperatures higher than 50/55 °C, which are thermally stable up to temperatures of at least 250 °C. Full article

(This article belongs to the Special Issue Biopolymers and Bioplastics)

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22 pages, 8871 KiB

Open AccessArticle

Functional Properties of Antimicrobial Neem Leaves Extract Based Macroalgae Biofilms for Potential Use as Active Dry Packaging Applications

by A. A. Oyekanmi, U. Seeta Uthaya Kumar, Abdul Khalil H. P. S., N. G. Olaiya, A. A. Amirul, A. A. Rahman, Arif Nuryawan, C. K. Abdullah and Samsul Rizal

Polymers 2021, 13(10), 1664; https://doi.org/10.3390/polym13101664 - 20 May 2021

Cited by 23 | Viewed by 4909

Abstract

Antimicrobial irradiated seaweed–neem biocomposite films were synthesized in this study. The storage functional properties of the films were investigated. Characterization of the prepared films was conducted using SEM, FT-IR, contact angle, and antimicrobial test. The macroscopic and microscopic including the analysis of the [...] Read more.

Antimicrobial irradiated seaweed–neem biocomposite films were synthesized in this study. The storage functional properties of the films were investigated. Characterization of the prepared films was conducted using SEM, FT-IR, contact angle, and antimicrobial test. The macroscopic and microscopic including the analysis of the functional group and the gas chromatography-mass spectrometry test revealed the main active constituents present in the neem extract, which was used an essential component of the fabricated films. Neem leaves’ extracts with 5% w/w concentration were incorporated into the matrix of seaweed biopolymer and the seaweed–neem bio-composite film were irradiated with different dosages of gamma radiation (0.5, 1, 1.5, and 2 kGy). The tensile, thermal, and the antimicrobial properties of the films were studied. The results revealed that the irradiated films exhibited improved functional properties compared to the control film at 1.5 kGy radiation dosage. The tensile strength, tensile modulus, and toughness exhibited by the films increased, while the elongation of the irradiated bio-composite film decreased compared to the control film. The morphology of the irradiated films demonstrated a smoother surface compared to the control and provided surface intermolecular interaction of the neem–seaweed matrix. The film indicated an optimum storage stability under ambient conditions and demonstrated no significant changes in the visual appearance. However, an increase in the moisture content was exhibited by the film, and the hydrophobic properties was retained until nine months of the storage period. The study of the films antimicrobial activities against Staphylococcus aureus (SA), and Bacillus subtilis (BS) indicated improved resistance to bacterial activities after the incorporation of neem leaves extract and gamma irradiation. The fabricated irradiated seaweed–neem bio-composite film could be used as an excellent sustainable packaging material due to its effective storage stability. Full article

(This article belongs to the Special Issue Biopolymers and Bioplastics)

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16 pages, 4024 KiB

Open AccessArticle

Citrus Pomace Biomass as a Source of Pectin and Lignocellulose Fibers: From Waste to Upgraded Biocomposites for Mulching Applications

by Domenico Zannini, Giovanni Dal Poggetto, Mario Malinconico, Gabriella Santagata and Barbara Immirzi

Polymers 2021, 13(8), 1280; https://doi.org/10.3390/polym13081280 - 14 Apr 2021

Cited by 49 | Viewed by 4998

Abstract

Citrus pomace derived from the industrial processing of juice and essential oils mostly consists of pectin, cellulose, hemicellulose, and simple sugars. In this work, citrus pomace waste from an agricultural company in South Italy was used as source of pectin. The extraction conditions [...] Read more.

Citrus pomace derived from the industrial processing of juice and essential oils mostly consists of pectin, cellulose, hemicellulose, and simple sugars. In this work, citrus pomace waste from an agricultural company in South Italy was used as source of pectin. The extraction conditions of the polysaccharide were optimized using a suitable combination of time and a concentration of a mild organic solvent, such as acetic acid; thus recovering high M_w pectin and bioactive molecules (flavonoids and polyphenols). The pectin was structurally (GPC, FTIR), morphologically (SEM), thermally (TGA/DTG), and mechanically characterized, while bioactive molecules were separated and the total phenolic content (TPC) and total flavonoids content (TFC) were evaluated. With the aim to develop novel biocomposite-based materials, the pectin extracted from citrus waste was reinforced with different amounts of lignocellulose fractions also recovered from citrus waste after polysaccharide extraction, according to a “zero waste” circular economy approach. The prepared biocomposites were morphologically and mechanically characterized to be used as biodegradable mulching systems for crop protection. Thus, the citrus waste biomass was recovered, fractionated into its main raw materials, and these were recombined to develop novel upgraded biocomposites for mulching applications, by means of a cost-effective and eco-sustainable approach. Full article

(This article belongs to the Special Issue Biopolymers and Bioplastics)

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13 pages, 25665 KiB

Open AccessArticle

Valorisation of Posidonia oceanica Sea Balls (Egagropili) as a Potential Source of Reinforcement Agents in Protein-Based Biocomposites

by Seyedeh Fatemeh Mirpoor, Concetta Valeria L. Giosafatto, Prospero Di Pierro, Rocco Di Girolamo, Carlos Regalado-González and Raffaele Porta

Polymers 2020, 12(12), 2788; https://doi.org/10.3390/polym12122788 - 25 Nov 2020

Cited by 18 | Viewed by 3648

Abstract

Nanocrystalline cellulose (NC) and a lignin-containing fraction (LF) were obtained from egagropili, the so called sea balls produced from rhizome and stem fragments of Posidonia oceanica that accumulate in large amounts along the coastal beaches in the form of tightly packed and dry [...] Read more.

Nanocrystalline cellulose (NC) and a lignin-containing fraction (LF) were obtained from egagropili, the so called sea balls produced from rhizome and stem fragments of Posidonia oceanica that accumulate in large amounts along the coastal beaches in the form of tightly packed and dry materials of various dimensions. Both egagropili fractions have been shown to be able to improve the physicochemical properties of biodegradable films prepared from protein concentrates derived from hemp oilseed cakes. These materials, manufactured with a biodegradable industrial by-product and grafted with equally biodegradable waste-derived additives, exhibited an acceptable resistance with a still high flexibility, as well as they showed an effective barrier activity against water vapor and gases (O₂ and CO₂). Furthermore, both NC and LF decreased film moisture content, swelling ability and solubility, thus indicating that both additives were able to improve water resistance of the hydrocolloid films. The exploitation of egagropili, actually considered only an undesirable waste to be disposed, as a renewable source of reinforcing agents to blend with different kinds of polymers is suggested. Full article

(This article belongs to the Special Issue Biopolymers and Bioplastics)

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17 pages, 3599 KiB

Open AccessArticle

Properties of Biodegradable Films Based on Poly(butylene Succinate) (PBS) and Poly(butylene Adipate-co-Terephthalate) (PBAT) Blends

by Anna Raffaela de Matos Costa, Andrea Crocitti, Laura Hecker de Carvalho, Sabrina Carola Carroccio, Pierfrancesco Cerruti and Gabriella Santagata

Polymers 2020, 12(10), 2317; https://doi.org/10.3390/polym12102317 - 10 Oct 2020

Cited by 121 | Viewed by 11165

Abstract

Compression molded biodegradable films based on poly(butylene succinate) (PBS) and poly(butylene adipate-co-terephthalate) (PBAT) at varying weights were prepared, and their relevant properties for packaging applications are here reported. The melt rheology of the blends was first studied, and the binary PBS/PBAT [...] Read more.

Compression molded biodegradable films based on poly(butylene succinate) (PBS) and poly(butylene adipate-co-terephthalate) (PBAT) at varying weights were prepared, and their relevant properties for packaging applications are here reported. The melt rheology of the blends was first studied, and the binary PBS/PBAT blends exhibited marked shear thinning and complex thermoreological behavior, due to the formation of a co-continuous morphology in the 50 wt% blend. The films were characterized by infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), mechanical tensile tests, scanning electron microscopy (SEM), and oxygen and water vapor permeability. PBS crystallization was inhibited in the blends with higher contents of PBAT, and FTIR and SEM analysis suggested that limited interactions occur between the two polymer phases. The films showed increasing stiffness as the PBS percentage increased; further, a sharp decrease in elongation at break was noticed for the films containing percentages of PBS greater than 25 wt%. Gas permeability decreased with increasing PBS content, indicating that the barrier properties of PBS can be tuned by blending with PBAT. The results obtained point out that the blend containing 25 wt% PBS is a good compromise between elastic modulus (135 MPa) and deformation at break (390%) values. Overall, PBS/PBAT blends represent an alternative for packaging films, as they combine biodegradability, good barrier properties and reasonable mechanical behavior. Full article

(This article belongs to the Special Issue Biopolymers and Bioplastics)

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