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19 pages, 3727 KiB

Open AccessArticle

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Bionanocomposites with Crystalline Nanocellulose and Graphene Oxide: Experimental Results and Support Vector Machine Modeling

by Elizabeth Champa-Bujaico, Ana M. Díez-Pascual and Pilar Garcia-Diaz

Polymers 2023, 15(18), 3746; https://doi.org/10.3390/polym15183746 - 13 Sep 2023

Cited by 1 | Viewed by 934

Abstract

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a biodegradable and biocompatible bacterial copolymer used in the biomedical and food industries. However, it displays low stiffness and strength for certain applications. This issue can be solved via reinforcement with nanofillers. In this work, PHBHHx-based bionanocomposites reinforced with different [...] Read more.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a biodegradable and biocompatible bacterial copolymer used in the biomedical and food industries. However, it displays low stiffness and strength for certain applications. This issue can be solved via reinforcement with nanofillers. In this work, PHBHHx-based bionanocomposites reinforced with different loadings of crystalline nanocellulose (CNC) and graphene oxide (GO) were developed by a green and straightforward solution casting technique. Their crystalline nature and surface topography were explored via X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively, their composition was corroborated via Fourier-transformed infrared spectroscopy (FTIR), and their crystallization and melting behavior were determined via differential scanning calorimetry (DSC). The nanofillers had a nucleating role, raising the crystallization temperature of the polymer, whilst hardly any changes were found in the melting temperature. Further, significant enhancements in the stiffness, strength, and thermal stability of the PHBHHx matrix were observed with the incorporation of both nanofillers, which was attributed to a synergic effect. The mechanical properties for various concentrations of CNC and GO were accurately predicted using a machine learning (ML) model in the form of a support vector machine (SVM). The model performance was evaluated in terms of the mean absolute error (MAE), the mean square error (MSE), and the correlation coefficient (R²). These bio-based nanocomposites are a valuable alternative to conventional petroleum-based synthetic polymeric materials used nowadays for biomedicine and food packaging applications. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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15 pages, 16483 KiB

Open AccessArticle

The Effects of the Deacetylation of Chitin Nanowhiskers on the Performance of PCL/PLA Bio-Nanocomposites

by Ivan Kelnar, Ludmila Kaprálková, Pavel Němeček, Jiří Dybal, Rasha M. Abdel-Rahman, Michaela Vyroubalová, Martina Nevoralová and A. M. Abdel-Mohsen

Polymers 2023, 15(14), 3071; https://doi.org/10.3390/polym15143071 - 17 Jul 2023

Cited by 1 | Viewed by 1158

Abstract

The multiple roles of organic nanofillers in biodegradable nanocomposites (NC) with a blend-based matrix is not yet fully understood. This work highlights combination of reinforcing and structure-directing effects of chitin nanowhiskers (CNW) with different degrees of deacetylation (DA), i.e., content of primary or [...] Read more.

The multiple roles of organic nanofillers in biodegradable nanocomposites (NC) with a blend-based matrix is not yet fully understood. This work highlights combination of reinforcing and structure-directing effects of chitin nanowhiskers (CNW) with different degrees of deacetylation (DA), i.e., content of primary or secondary amines on their surface, in the nanocomposite with the PCL/PLA 1:1 matrix. Of importance is the fact that aminolysis with CNW leading to chain scission of both polyesters, especially of PLA, is practically independent of DA. DA also does not influence thermal stability. At the same time, the more marked chain scission/CNW grafting for PLA in comparison to PCL, causing changes in rheological parameters of components and related structural alterations, has crucial effects on mechanical properties in systems with a bicontinuous structure. Favourable combinations of multiple effects of CNW leads to enhanced mechanical performance at low 1% content only, whereas negative effects of structural changes, particularly of changed continuity, may eliminate the reinforcing effects of CNW at higher contents. The explanation of both synergistic and antagonistic effects of structures formed is based on the correspondence of experimental results with respective basic model calculations. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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22 pages, 7404 KiB

Open AccessArticle

Composites Based on Poly(ε-caprolactone) and Graphene Oxide Modified with Oligo/Poly(Glutamic Acid) as Biomaterials with Osteoconductive Properties

by Olga Solomakha, Mariia Stepanova, Iosif Gofman, Yulia Nashchekina, Maxim Rabchinskii, Alexey Nashchekin, Antonina Lavrentieva and Evgenia Korzhikova-Vlakh

Polymers 2023, 15(12), 2714; https://doi.org/10.3390/polym15122714 - 17 Jun 2023

Cited by 1 | Viewed by 1276

Abstract

The development of new biodegradable biomaterials with osteoconductive properties for bone tissue regeneration is one of the urgent tasks of modern medicine. In this study, we proposed the pathway for graphene oxide (GO) modification with oligo/poly(glutamic acid) (oligo/poly(Glu)) possessing osteoconductive properties. The modification [...] Read more.

The development of new biodegradable biomaterials with osteoconductive properties for bone tissue regeneration is one of the urgent tasks of modern medicine. In this study, we proposed the pathway for graphene oxide (GO) modification with oligo/poly(glutamic acid) (oligo/poly(Glu)) possessing osteoconductive properties. The modification was confirmed by a number of methods such as Fourier-transform infrared spectroscopy, quantitative amino acid HPLC analysis, thermogravimetric analysis, scanning electron microscopy, and dynamic and electrophoretic light scattering. Modified GO was used as a filler for poly(ε-caprolactone) (PCL) in the fabrication of composite films. The mechanical properties of the biocomposites were compared with those obtained for the PCL/GO composites. An 18–27% increase in elastic modulus was found for all composites containing modified GO. No significant cytotoxicity of the GO and its derivatives in human osteosarcoma cells (MG-63) was revealed. Moreover, the developed composites stimulated the proliferation of human mesenchymal stem cells (hMSCs) adhered to the surface of the films in comparison with unfilled PCL material. The osteoconductive properties of the PCL-based composites filled with GO modified with oligo/poly(Glu) were confirmed via alkaline phosphatase assay as well as calcein and alizarin red S staining after osteogenic differentiation of hMSC in vitro. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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19 pages, 5157 KiB

Open AccessArticle

Carrageenan/Chitin Nanowhiskers Cryogels for Vaginal Delivery of Metronidazole

by Natallia V. Dubashynskaya, Valentina A. Petrova, Andrey V. Sgibnev, Vladimir Y. Elokhovskiy, Yuliya I. Cherkasova and Yury A. Skorik

Polymers 2023, 15(10), 2362; https://doi.org/10.3390/polym15102362 - 18 May 2023

Cited by 1 | Viewed by 1301

Abstract

The development of polymeric carriers based on partially deacetylated chitin nanowhiskers (CNWs) and anionic sulfated polysaccharides is an attractive strategy for improved vaginal delivery with modified drug release profiles. This study focuses on the development of metronidazole (MET)-containing cryogels based on carrageenan (CRG) [...] Read more.

The development of polymeric carriers based on partially deacetylated chitin nanowhiskers (CNWs) and anionic sulfated polysaccharides is an attractive strategy for improved vaginal delivery with modified drug release profiles. This study focuses on the development of metronidazole (MET)-containing cryogels based on carrageenan (CRG) and CNWs. The desired cryogels were obtained by electrostatic interactions between the amino groups of CNWs and the sulfate groups of CRG and by the formation of additional hydrogen bonds, as well as by entanglement of carrageenan macrochains. It was shown that the introduction of 5% CNWs significantly increased the strength of the initial hydrogel and ensured the formation of a homogeneous cryogel structure, resulting in sustained MET release within 24 h. At the same time, when the CNW content was increased to 10%, the system collapsed with the formation of discrete cryogels, demonstrating MET release within 12 h. The mechanism of prolonged drug release was mediated by polymer swelling and chain relaxation in the polymer matrix and correlated well with the Korsmeyer–Peppas and Peppas–Sahlin models. In vitro tests showed that the developed cryogels had a prolonged (24 h) antiprotozoal effect against Trichomonas, including MET-resistant strains. Thus, the new cryogels with MET may be promising dosage forms for the treatment of vaginal infections. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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20 pages, 7107 KiB

Open AccessArticle

Water Influence on the Physico-Chemical Properties and 3D Printability of Choline Acrylate—Bacterial Cellulose Inks

by Veronika S. Fedotova, Maria P. Sokolova, Vitaly K. Vorobiov, Eugene V. Sivtsov, Natalia V. Lukasheva and Michael A. Smirnov

Polymers 2023, 15(9), 2156; https://doi.org/10.3390/polym15092156 - 30 Apr 2023

Cited by 5 | Viewed by 1460

Abstract

The aim of this work was to study the influence of water as a co-solvent on the interaction between a polymerizable ionic liquid—choline acrylate (ChA)—and bacterial cellulose. Bacterial cellulose dispersed in ChA is a new type of UV-curable biopolymer-based ink that is a [...] Read more.

The aim of this work was to study the influence of water as a co-solvent on the interaction between a polymerizable ionic liquid—choline acrylate (ChA)—and bacterial cellulose. Bacterial cellulose dispersed in ChA is a new type of UV-curable biopolymer-based ink that is a prospective material for the 3D printing of green composite ion-gels. Higher cellulose content in inks is beneficial for the ecological and mechanical properties of materials, and leads to increased viscosity and the yield stress of such systems and hampers printability. It was found that the addition of water results in (1) a decrease in the solvent viscosity and yield stress; and (2) a decrease in the stability of dispersion toward phase separation under stress. In this work, an optimal composition in the range of 30–40 wt% water content demonstrating 97–160 Pa of yield stress was found that ensures the printability and stability of inks. The rheological properties of inks and mechanical characteristics (0.7–0.8 MPa strength and 1.1–1.2 MPa Young’s modulus) were obtained. The mechanism of influence of the ratio ChA/water on the properties of ink was revealed with atomic force microscopy, wide-angle X-ray diffraction studies of bacterial cellulose after regeneration from solvent, and computer simulation of ChA/water mixtures and their interaction with the cellulose surface. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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19 pages, 3125 KiB

Open AccessArticle

Poly(Butylene Succinate) Hybrid Multi-Walled Carbon Nanotube/Iron Oxide Nanocomposites: Electromagnetic Shielding and Thermal Properties

by Miks Bleija, Oskars Platnieks, Jan Macutkevič, Jūras Banys, Olesja Starkova, Liga Grase and Sergejs Gaidukovs

Polymers 2023, 15(3), 515; https://doi.org/10.3390/polym15030515 - 18 Jan 2023

Cited by 8 | Viewed by 1630

Abstract

To address the ever-increasing electromagnetic interference (EMI) pollution, a hybrid filler approach for novel composites was chosen, with a focus on EMI absorbance. Carbon nanofiller loading was limited to 0.6 vol.% in order to create a sustainable and affordable solution. Multiwall carbon nanotubes [...] Read more.

To address the ever-increasing electromagnetic interference (EMI) pollution, a hybrid filler approach for novel composites was chosen, with a focus on EMI absorbance. Carbon nanofiller loading was limited to 0.6 vol.% in order to create a sustainable and affordable solution. Multiwall carbon nanotubes (MWCNT) and iron oxide (Fe₃O₄) nanoparticles were mixed in nine ratios from 0.1 to 0.6 vol.% and 8.0 to 12.0 vol.%, respectively. With the addition of surfactant, excellent particle dispersion was achieved (examined with SEM micrographs) in a bio-based and biodegradable poly(butylene succinate) (PBS) matrix. Hybrid design synergy was assessed for EMI shielding using dielectric spectroscopy in the microwave region and transmittance in the terahertz range. The shielding effectiveness (20–52 dB) was dominated by very high absorption at 30 GHz, while in the 0.1 to 1.0 THz range, transmittance was reduced by up to 6 orders of magnitude. Frequency-independent AC electrical conductivity (from 10⁻² to 10⁷ Hz) was reached upon adding 0.6 vol.% MWCNT and 10 vol.% Fe₃O₄, with a value of around 3.1 × 10⁻² S/m. Electrical and thermal conductivity were mainly affected by the content of MWCNT filler. The thermal conductivity scaled with the filler content and reached the highest value of 0.309 W/(mK) at 25 °C with the loading of 0.6 vol.% MWCNT and 12 vol.% Fe₃O₄. The surface resistivity showed an incremental decrease with an increase in MWCNT loading and was almost unaffected by an increase in iron oxide loading. Thermal conductivity was almost independent of temperature in the measured range of 25 to 45 °C. The nanocomposites serve as biodegradable alternatives to commodity plastic-based materials and are promising in the field of electromagnetic applications, especially for EMI shielding. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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15 pages, 3213 KiB

Open AccessArticle

Phase Morphology, Mechanical, and Thermal Properties of Calcium Carbonate-Reinforced Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) Bioplastics

by Prasong Srihanam, Wiriya Thongsomboon and Yodthong Baimark

Polymers 2023, 15(2), 301; https://doi.org/10.3390/polym15020301 - 06 Jan 2023

Cited by 6 | Viewed by 2136

Abstract

Poly(L-lactide) (PLLA) is a promising candidate as a bioplastic because of its non-toxicity and biodegradability. However, the low flexibility of PLLA limits its use in many applications. Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-b-PEG-b-PLLA) block copolymer is of interest [...] Read more.

Poly(L-lactide) (PLLA) is a promising candidate as a bioplastic because of its non-toxicity and biodegradability. However, the low flexibility of PLLA limits its use in many applications. Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-b-PEG-b-PLLA) block copolymer is of interest for bioplastic applications due to its superior flexibility compared to PLLA. The aim of this work is to modify PLLA-b-PEG-b-PLLA using a low-cost calcium carbonate (CaCO₃) filler to improve material properties compared to PLLA/CaCO₃ composites. The addition of CaCO₃ enhanced the crystallinity and thermal stability for the PLLA-b-PEG-b-PLLA matrix but not for the PLLA matrix, as determined by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). Phase morphology investigation using scanning electron microscopy (SEM) revealed that the interfacial adhesion between PLLA-b-PEG-b-PLLA and CaCO₃ was stronger than between PLLA and CaCO₃. Additionally, tensile testing was carried out to determine the mechanical properties of the composites. With the addition of CaCO₃, the tensile stress and Young’s modulus of the PLLA-b-PEG-b-PLLA matrix were increased, whereas these properties of the PLLA matrix were significantly decreased. Thus, CaCO₃ shows great promise as an inexpensive filler that can induce nucleation and reinforcing effects for PLLA-b-PEG-b-PLLA bioplastics. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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18 pages, 2745 KiB

Open AccessArticle

Valorization of Kraft Lignin from Black Liquor in the Production of Composite Materials with Poly(caprolactone) and Natural Stone Groundwood Fibers

by Quim Tarrés, Roberto Aguado, Juan Domínguez-Robles, Eneko Larrañeta and Marc Delgado-Aguilar

Polymers 2022, 14(23), 5178; https://doi.org/10.3390/polym14235178 - 28 Nov 2022

Cited by 2 | Viewed by 1655

Abstract

The development of new materials is currently focused on replacing fossil-based plastics with sustainable materials. Obtaining new bioplastics that are biodegradable and of the greenest possible origin could be a great alternative for the future. However, there are some limitations—such as price, physical [...] Read more.

The development of new materials is currently focused on replacing fossil-based plastics with sustainable materials. Obtaining new bioplastics that are biodegradable and of the greenest possible origin could be a great alternative for the future. However, there are some limitations—such as price, physical properties, and mechanical properties—of these bioplastics. In this sense, the present work aims to explore the potential of lignin present in black liquor from paper pulp production as the main component of a new plastic matrix. For this purpose, we have studied the simple recovery of this lignin using acid precipitation, its thermoplastification with glycerin as a plasticizing agent, the production of blends with poly(caprolactone) (PCL), and finally the development of biocomposite materials reinforcing the blend of thermoplastic lignin and PCL with stone groundwood fibers (SGW). The results obtained show that thermoplastic lignin alone cannot be used as a bioplastic. However, its combination with PCL provided a tensile strength of, e.g., 5.24 MPa in the case of a 50 wt.% blend. In addition, when studying the properties of the composite materials, it was found that the tensile strength of a blend with 20 wt.% PCL increased from 1.7 to 11.2 MPa with 40 wt.% SGW. Finally, it was proven that through these biocomposites it is possible to obtain a correct fiber–blend interface. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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18 pages, 4435 KiB

Open AccessArticle

Bacterial Cellulose Composites with Polysaccharides Filled with Nanosized Cerium Oxide: Characterization and Cytocompatibility Assessment

by Valentina A. Petrova, Iosif V. Gofman, Alexey S. Golovkin, Alexander I. Mishanin, Natallia V. Dubashynskaya, Albert K. Khripunov, Elena M. Ivan’kova, Elena N. Vlasova, Alexandra L. Nikolaeva, Alexander E. Baranchikov, Yury A. Skorik, Alexander V. Yakimansky and Vladimir K. Ivanov

Polymers 2022, 14(22), 5001; https://doi.org/10.3390/polym14225001 - 18 Nov 2022

Cited by 6 | Viewed by 1470

Abstract

A new biocompatible nanocomposite film material for cell engineering and other biomedical applications has been prepared. It is based on the composition of natural polysaccharides filled with cerium oxide nanoparticles (CeONPs). The preparative procedure consists of successive impregnations of pressed bacterial cellulose (BC) [...] Read more.

A new biocompatible nanocomposite film material for cell engineering and other biomedical applications has been prepared. It is based on the composition of natural polysaccharides filled with cerium oxide nanoparticles (CeONPs). The preparative procedure consists of successive impregnations of pressed bacterial cellulose (BC) with a sodium alginate (ALG) solution containing nanoparticles of citrate-stabilized cerium oxide and a chitosan (CS) solution. The presence of CeONPs in the polysaccharide composite matrix and the interaction of the nanoparticles with the polymer, confirmed by IR spectroscopy, change the network architecture of the composite. This leads to noticeable changes in a number of properties of the material in comparison with those of the matrix’s polysaccharide composition, viz., an increase in mechanical stiffness, a decrease in the degree of planar orientation of BC macrochains, an increase in hydrophilicity, and the shift of the processes of thermo-oxidative destruction of the material to a low-temperature region. The latter effect is considered to be caused by the redox activity of cerium oxide (reversible transitions between the states Ce⁴⁺ and Ce³⁺) in thermally stimulated processes in the nanocomposite films. In the equilibrium swollen state, the material retains a mechanical strength at the level of ~2 MPa. The results of in vitro tests (cultivation of multipotent mesenchymal stem cells) have demonstrated the good biocompatibility of the BC-ALG(CeONP)-CS film as cell proliferation scaffolds. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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13 pages, 2850 KiB

Open AccessArticle

Different Preparation Method of Nanocellulose from Macaranga gigantea and Its Preliminary Study on Packaging Film Potential

by Latifah Jasmani, Nurul Ain Nadirah Jamaluddin, Rafeadah Rusli, Sharmiza Adnan and Sarani Zakaria

Polymers 2022, 14(21), 4591; https://doi.org/10.3390/polym14214591 - 28 Oct 2022

Cited by 3 | Viewed by 1687

Abstract

Nanocellulose is a versatile cellulosic nanomaterial that can be used in many application areas. Applying different preparation strategies leads to different types of nanocellulose. In this study, nanocrystalline cellulose (NCC) and nanofibrillated cellulose (NFC) were prepared from lesser known wood species, viz., Macaranga [...] Read more.

Nanocellulose is a versatile cellulosic nanomaterial that can be used in many application areas. Applying different preparation strategies leads to different types of nanocellulose. In this study, nanocrystalline cellulose (NCC) and nanofibrillated cellulose (NFC) were prepared from lesser known wood species, viz., Macaranga gigantea, using sulfuric acid hydrolysis and enzymatic pretreatment with ultrafine grinding approaches, respectively. The respective nanocellulose was characterized by means of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), atomic force microscopy (AFM). It was then converted into a thin film to assess its performance which includes tensile test, transparency, air permeance, water vapor transmission rate (WVTR), and water vapor permeability (WVP) properties. NCC and NFC produced from the raw material of Macaranga had average widths of 6.38 ± 3.92 nm and 13.17 ± 12.71 nm, respectively. Peaks in FTIR spectra showed the conversion of Macaranga wood to nanocellulose by the presence of cellulose fingerprint as well as absence of lignin and hemicellulose after alkaline treatment. The successful conversion was also supported by XRD analysis which displayed the increased crystallinity value from 54% to 70%. TGA decomposition pattern at 200–490 °C revealed the thermal stability of the samples. The thin film produced from nanocelluloses had WVTR values of 4.58 and 12.14 g/(day·m²) for NFC and NCC, respectively, comparable to those of films from polyester and oriented polypropylene. Nanocellulose-based thin film has the potential to be used as sustainable and biodegradable packaging. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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13 pages, 9574 KiB

Open AccessArticle

Additive Manufacturing of Drug-Eluting Multilayer Biodegradable Films

by Pavel I. Proshin, Arkady S. Abdurashitov, Olga A. Sindeeva, Anastasia A. Ivanova and Gleb B. Sukhorukov

Polymers 2022, 14(20), 4318; https://doi.org/10.3390/polym14204318 - 14 Oct 2022

Cited by 1 | Viewed by 1660

Abstract

Drug-eluting films made of bioresorbable polymers are a widely used tool of modern personalized medicine. However, most currently existing methods of producing coatings do not go beyond the laboratory, as they have low encapsulation efficiency and/or difficulties in scaling up. The PLACE (Printed [...] Read more.

Drug-eluting films made of bioresorbable polymers are a widely used tool of modern personalized medicine. However, most currently existing methods of producing coatings do not go beyond the laboratory, as they have low encapsulation efficiency and/or difficulties in scaling up. The PLACE (Printed Layered Adjustable Cargo Encapsulation) technology proposed in this article uses an additive approach for film manufacturing. PLACE technology is accessible, scalable, and reproducible in any laboratory. As a demonstration of the technology capabilities, we fabricated layered drug-eluting polyglycolic acid films containing different concentrations of Cefazolin antibiotic. The influence of the amount of loaded drug component on the film production process and the release kinetics was studied. The specific loading of drugs was significantly increased to 200–400 µg/cm² while maintaining the uniform release of Cefazolin antibiotic in a dosage sufficient for local antimicrobial therapy for 14 days. The fact that the further increase in the drug amount results in the crystallization of a substance, which can lead to specific defects in the cover film formation and accelerated one-week cargo release, was also shown, and options for further technology development were proposed. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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14 pages, 2906 KiB

Open AccessArticle

Enhancement in Crystallizability of Poly(L-Lactide) Using Stereocomplex-Polylactide Powder as a Nucleating Agent

by Yodthong Baimark, Prasong Srihanam, Yaowalak Srisuwan and Theeraphol Phromsopha

Polymers 2022, 14(19), 4092; https://doi.org/10.3390/polym14194092 - 29 Sep 2022

Cited by 8 | Viewed by 1332

Abstract

High-molecular-weight poly(L-lactide) (HMW-PLLA) is a promising candidate for use as a bioplastic because of its biodegradability and compostability. However, the applications of HMW-PLLA have been limited due to its poor crystallizability. In this work, stereocomplex polylactide (scPLA) powder was prepared by [...] Read more.

High-molecular-weight poly(L-lactide) (HMW-PLLA) is a promising candidate for use as a bioplastic because of its biodegradability and compostability. However, the applications of HMW-PLLA have been limited due to its poor crystallizability. In this work, stereocomplex polylactide (scPLA) powder was prepared by precipitation of a low-molecular-weight poly(L-lactide)/poly(D-lactide) (LMW-PLLA/LMW-PDLA) blend solution and investigated for use as a fully-biodegradable nucleating agent for HMW-PLLA compared to LMW-PLLA powder. The obtained LMW-PLLA and scPLA powders with a nearly spherical shape showed complete homo- and stereocomplex crystallites, respectively. HMW-PLLA/LMW-PLLA powder and HMW-PLLA/scPLA powder blends were prepared by melt blending. The LMW-PLLA powder was homogeneously melted in the HMW-PLLA matrices, whereas the scPLA powder had good phase compatibility and was well-dispersed in the HMW-PLLA matrices, as detected by scanning electron microscopy (SEM). It was shown that the enthalpies of crystallization (ΔH_c) upon cooling scans for HMW-PLLA largely increased and the half crystallization time (t_1/2) dramatically decreased as the scPLA powder content increased; however, the LMW-PLLA powder did not exhibit the same behavior, as determined by differential scanning calorimetry (DSC). The crystallinity content of the HMW-PLLA/scPLA powder blends significantly increased as the scPLA powder content increased, as determined by DSC and X-ray diffractometry (XRD). In conclusion, the fully biodegradable scPLA powder showed good potential for use as an effective nucleating agent to improve the crystallization properties of the HMW-PLLA bioplastic. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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20 pages, 715 KiB

Open AccessReview

The Potential Applications of Reinforced Bioplastics in Various Industries: A Review

by Uwei Kong, Nurul Fazita Mohammad Rawi and Guan Seng Tay

Polymers 2023, 15(10), 2399; https://doi.org/10.3390/polym15102399 - 22 May 2023

Cited by 9 | Viewed by 7245

Abstract

The introduction of bioplastics has been an evolution for plastic industry since conventional plastics have been claimed to cause several environmental issues. Apart from its biodegradability, one of the advantages can be identified of using bioplastic is that they are produced by renewal [...] Read more.

The introduction of bioplastics has been an evolution for plastic industry since conventional plastics have been claimed to cause several environmental issues. Apart from its biodegradability, one of the advantages can be identified of using bioplastic is that they are produced by renewal resources as the raw materials for synthesis. Nevertheless, bioplastics can be classified into two types, which are biodegradable and non-biodegradable, depending on the type of plastic that is produced. Although some of the bioplastics are non-biodegradable, the usage of biomass in synthesising the bioplastics helps in preserving non-renewable resources, which are petrochemical, in producing conventional plastics. However, the mechanical strength of bioplastic still has room for improvement as compared to conventional plastics, which is believed to limit its application. Ideally, bioplastics need to be reinforced for improving their performance and properties to serve their application. Before 21st century, synthetic reinforcement has been used to reinforce conventional plastic to achieve its desire properties to serve its application, such as glass fiber. Owing to several issues, the trend has been diversified to utilise natural resources as reinforcements. There are several industries that have started to use reinforced bioplastic, and this article focuses on the advantages of using reinforced bioplastic in various industries and its limitations. Therefore, this article aims to study the trend of reinforced bioplastic applications and the potential applications of reinforced bioplastics in various industries. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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23 pages, 5401 KiB

Open AccessReview

Sources, Chemical Functionalization, and Commercial Applications of Nanocellulose and Nanocellulose-Based Composites: A Review

by Danish Tahir, Muhammad Ramzan Abdul Karim, Hong Hu, Sufyan Naseem, Muhammad Rehan, Mairaj Ahmad and Minglonghai Zhang

Polymers 2022, 14(21), 4468; https://doi.org/10.3390/polym14214468 - 22 Oct 2022

Cited by 15 | Viewed by 3343

Abstract

Nanocellulose is the most abundant material extracted from plants, animals, and bacteria. Nanocellulose is a cellulosic material with nano-scale dimensions and exists in the form of cellulose nanocrystals (CNC), bacterial nanocellulose (BNC), and nano-fibrillated cellulose (NFC). Owing to its high surface area, non-toxic [...] Read more.

Nanocellulose is the most abundant material extracted from plants, animals, and bacteria. Nanocellulose is a cellulosic material with nano-scale dimensions and exists in the form of cellulose nanocrystals (CNC), bacterial nanocellulose (BNC), and nano-fibrillated cellulose (NFC). Owing to its high surface area, non-toxic nature, good mechanical properties, low thermal expansion, and high biodegradability, it is obtaining high attraction in the fields of electronics, paper making, packaging, and filtration, as well as the biomedical industry. To obtain the full potential of nanocellulose, it is chemically modified to alter the surface, resulting in improved properties. This review covers the nanocellulose background, their extraction methods, and possible chemical treatments that can enhance the properties of nanocellulose and its composites, as well as their applications in various fields. Full article

(This article belongs to the Special Issue Advances in Bio-Based and Biodegradable Polymeric Composites II)

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