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  • 1
    Online Resource
    Online Resource
    Tailored Biobased Resins from Acrylated Vegetable Oils for Application in Wood Coatings
    MDPI AG ; 2023
    In:  Coatings Vol. 13, No. 3 ( 2023-03-20), p. 657-
    Details
    In: Coatings, MDPI AG, Vol. 13, No. 3 ( 2023-03-20), p. 657-
    Abstract: The modern coating market is dominated by acrylic, polyurethane, and polyester polymer resins produced from unsustainable fossil resources. Herein, we propose the preparation of resins from biobased components to produce functional and solvent-free wood coatings with enhanced performance properties. Acrylated rapeseed, linseed, and grapeseed oils were prepared via a one-step synthesis and used as a basis for the control of resin viscosity and fatty acid content. A combination of vegetable oil acrylates was used as a matrix and the biobased monomer propoxylated glycerol triacrylate (GPT) was selected to tailor the properties of the UV crosslinked network. During polymerization, the GPT monomer induced a two-phase microstructure as indicated by an SEM analysis. The possibility of generating a tailored microstructure in the final material was examined in this study. The addition of GPT increased the storage modulus by up to five-fold, crosslink density by up to two-fold at 20 °C, and glass transition temperature by up to 10.2 °C. Pull-off adhesion tests showed a strength of 1.21 MPa. In addition, the photo-oxidation effect on samples, i.e., aging, was assessed with microhardness, sliding friction, and optical microscopy. Coatings showed a microhardness value up to 250 MPa, while a coefficient of friction (μ) was in the range of 0.21 to 0.88.
    Type of Medium: Online Resource
    ISSN: 2079-6412
    URL: Article
    DOI: 10.3390/coatings13030657
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2662314-6
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  • 2
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    Online Resource
    Sustainable Wax Coatings Made from Pine Needle Extraction Waste for Nanopaper Hydrophobization
    MDPI AG ; 2022
    In:  Membranes Vol. 12, No. 5 ( 2022-05-20), p. 537-
    Details
    In: Membranes, MDPI AG, Vol. 12, No. 5 ( 2022-05-20), p. 537-
    Abstract: We combine renewable and waste materials to produce hydrophobic membranes in the present work. Cellulose nanopaper prepared from paper waste was used as a structural component for the membrane. The pine wax was reclaimed from pine needle extraction waste and can be regarded as a byproduct. The dip-coating and spray-coating methods were comprehensively compared. In addition, the solubility of wax in different solvents is reported, and the concentration impact on coating quality is presented as the change in the contact angle value. The sensile drop method was used for wetting measurements. Spray-coating yielded the highest contact angle with an average of 114°, while dip-coating reached an average value of 107°. Scanning electron microscopy (SEM) was used for an in-depth comparison of surface morphology. It was observed that coating methods yield significantly different microstructures on the surface of cellulose fibers. The wax is characterized by nuclear magnetic resonance (NMR) spectroscopy and differential scanning calorimetry (DSC). Pine wax has a melting temperature of around 80 °C and excellent thermal stability in oxygen, with a degradation peak above 290 °C. Fourier transform infrared spectroscopy (FTIR) was used to identify characteristic groups of components and show the changes on coated nanopaper. Overall, the results of this work yield important insight into wax-coated cellulose nanopapers and a comparison of spray- and dip-coating methods. The prepared materials have a potential application as membranes and packaging materials.
    Type of Medium: Online Resource
    ISSN: 2077-0375
    URL: Article
    DOI: 10.3390/membranes12050537
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2614641-1
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  • 3
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    Online Resource
    Lignin and Xylan as Interface Engineering Additives for Improved Environmental Durability of Sustainable Cellulose Nanopapers
    MDPI AG ; 2021
    In:  International Journal of Molecular Sciences Vol. 22, No. 23 ( 2021-11-29), p. 12939-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 22, No. 23 ( 2021-11-29), p. 12939-
    Abstract: Cellulose materials and products are frequently affected by environmental factors such as light, temperature, and humidity. Simulated UV irradiation, heat, and moisture exposure were comprehensively used to characterize changes in cellulose nanopaper (NP) tensile properties. For the preparation of NP, high-purity cellulose from old, unused filter paper waste was used. Lignin and xylan were used as sustainable green interface engineering modifiers for NP due to their structural compatibility, low price, nontoxic nature, and abundance as a by-product of biomass processing, as well as their ability to protect cellulose fibers from UV irradiation. Nanofibrillated cellulose (NFC) suspension was obtained by microfluidizing cellulose suspension, and NP was produced by casting films from water suspensions. The use of filler from 1 to 30 wt% significantly altered NP properties. All nanopapers were tested for their sensitivity to water humidity, which reduced mechanical properties from 10 to 40% depending on the saturation level. Xylan addition showed a significant increase in the specific elastic modulus and specific strength by 1.4- and 2.8-fold, respectively. Xylan-containing NPs had remarkable resistance to UV irradiation, retaining 50 to 90% of their initial properties. Lignin-modified NPs resulted in a decreased mechanical performance due to the particle structure of the filler and the agglomeration process, but it was compensated by good property retention and enhanced elongation. The UV oxidation process of the NP interface was studied with UV-Vis and FTIR spectroscopy, which showed that the degradation of lignin and xylan preserves a cellulose fiber structure. Scanning electron microscopy images revealed the structural formation of the interface and supplemented understanding of UV aging impact on the surface and penetration depth in the cross-section. The ability to overcome premature aging in environmental factors can significantly benefit the wide adaption of NP in food packaging and functional applications.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms222312939
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 4
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    Online Resource
    Biorefinery Approach for Aerogels
    MDPI AG ; 2020
    In:  Polymers Vol. 12, No. 12 ( 2020-11-24), p. 2779-
    Details
    In: Polymers, MDPI AG, Vol. 12, No. 12 ( 2020-11-24), p. 2779-
    Abstract: According to the International Energy Agency, biorefinery is “the sustainable processing of biomass into a spectrum of marketable bio-based products (chemicals, materials) and bioenergy (fuels, power, heat)”. In this review, we survey how the biorefinery approach can be applied to highly porous and nanostructured materials, namely aerogels. Historically, aerogels were first developed using inorganic matter. Subsequently, synthetic polymers were also employed. At the beginning of the 21st century, new aerogels were created based on biomass. Which sources of biomass can be used to make aerogels and how? This review answers these questions, paying special attention to bio-aerogels’ environmental and biomedical applications. The article is a result of fruitful exchanges in the frame of the European project COST Action “CA 18125 AERoGELS: Advanced Engineering and Research of aeroGels for Environment and Life Sciences”.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    URL: Article
    DOI: 10.3390/polym12122779
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2527146-5
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  • 5
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    Online Resource
    Poly(Butylene Succinate) Hybrid Multi-Walled Carbon Nanotube/Iron Oxide Nanocomposites: Electromagnetic Shielding and Thermal Properties
    MDPI AG ; 2023
    In:  Polymers Vol. 15, No. 3 ( 2023-01-18), p. 515-
    Details
    In: Polymers, MDPI AG, Vol. 15, No. 3 ( 2023-01-18), p. 515-
    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 (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.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    URL: Article
    DOI: 10.3390/polym15030515
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
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  • 6
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    Online Resource
    Lamination of Cast Hemp Paper with Bio-Based Plastics for Sustainable Packaging: Structure-Thermomechanical Properties Relationship and Biodegradation Studies
    MDPI AG ; 2022
    In:  Journal of Composites Science Vol. 6, No. 9 ( 2022-08-24), p. 246-
    Details
    In: Journal of Composites Science, MDPI AG, Vol. 6, No. 9 ( 2022-08-24), p. 246-
    Abstract: Composite laminate recycling and waste disposal routes remain a burden to existing systems, requiring special treatment and separation. The inclusion of a plastic layer is important for several key properties that are required for food safety, which in turn has made these products exceptionally hard to substitute in food packaging. Yet, the continued use of non-degradable commodity plastics is unsustainable. In this research, we compare the four most promising biodegradable and bio-based plastics that could replace non-degradable plastics in laminates. Polyhydroxyalkanoate (PHA), polylactic acid (PLA), polybutylene succinate (PBS), and polybutylene succinate adipate (PBSA) were applied as a direct melt coating on porous cast hemp papers, and the final composite was compressed under three different loads: 0.5 MT, 1.5 MT, and 3.0 MT. To promote sustainable agriculture waste management, we opted to use cast paper made from ground hemp stalks. The formation of the composite structure was examined with scanning electron microscopy (SEM), while surface wetting on the paper side of the laminate was performed to understand structural changes induced by polymer impregnation into the paper layer. Mechanical performance properties were investigated with tensile and peel tests, and suitability for an extended range of temperatures was examined with dynamical mechanical analysis. An increase in compression pressure yielded up to a two-fold improvement in elastic modulus and tensile strength, while thermomechanical analysis revealed that the polymer’s transition into a viscoelastic state significantly affected the laminate’s storage modulus values. Biodegradation was performed in a controlled compost at 58 °C, resulting in full degradation within 40 to 80 days, with PLA and PHA laminates showing 40 and 50 days, respectively. Produced bioplastic laminates have a tremendous potential to replace polyolefin laminates in packaging applications.
    Type of Medium: Online Resource
    ISSN: 2504-477X
    URL: Article
    DOI: 10.3390/jcs6090246
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2911719-7
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  • 7
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    Bio-Based Poly(butylene succinate)/Microcrystalline Cellulose/Nanofibrillated Cellulose-Based Sustainable Polymer Composites: Thermo-Mechanical and Biodegradation Studies
    MDPI AG ; 2020
    In:  Polymers Vol. 12, No. 7 ( 2020-06-30), p. 1472-
    Details
    In: Polymers, MDPI AG, Vol. 12, No. 7 ( 2020-06-30), p. 1472-
    Abstract: Biodegradable polymer composites from renewable resources are the next-generation of wood-like materials and are crucial for the development of various industries to meet sustainability goals. Functional applications like packaging, medicine, automotive, construction and sustainable housing are just some that would greatly benefit. Some of the existing industries, like wood plastic composites, already encompass given examples but are dominated by fossil-based polymers that are unsustainable. Thus, there is a background to bring a new perspective approach for the combination of microcrystalline cellulose (MCC) and nanofibrillated cellulose (NFC) fillers in bio-based poly (butylene succinate) matrix (PBS). MCC, NFC and MCC/NFC filler total loading at 40 wt % was used to obtain more insights for wood-like composite applications. The ability to tailor the biodegradable characteristics and the mechanical properties of PBS composites is indispensable for extended applications. Five compositions have been prepared with MCC and NFC fillers using melt blending approach. Young’s modulus in tensile test mode and storage modulus at 20 °C in thermo-mechanical analysis have increased about two-fold. Thermal degradation temperature was increased by approximately 60 °C compared to MCC and NFC. Additionally, to estimate the compatibility of the components and morphology of the composite’s SEM analysis was performed for fractured surfaces. The contact angle measurements testified the developed matrix interphase. Differential scanning calorimetry evidenced the trans-crystallization of the polymer after filler incorporation; the crystallization temperature shifted to the higher temperature region. The MCC has a stronger effect on the crystallinity degree than NFC filler. PBS disintegrated under composting conditions in a period of 75 days. The NFC/MCC addition facilitated the specimens’ decomposition rate up to 60 days
    Type of Medium: Online Resource
    ISSN: 2073-4360
    URL: Article
    DOI: 10.3390/polym12071472
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
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  • 8
    Online Resource
    Online Resource
    Durability of Biodegradable Polymer Nanocomposites
    MDPI AG ; 2021
    In:  Polymers Vol. 13, No. 19 ( 2021-09-30), p. 3375-
    Details
    In: Polymers, MDPI AG, Vol. 13, No. 19 ( 2021-09-30), p. 3375-
    Abstract: Biodegradable polymers (BP) are often regarded as the materials of the future, which address the rising environmental concerns. The advancement of biorefineries and sustainable technologies has yielded various BP with excellent properties comparable to commodity plastics. Water resistance, high dimensional stability, processability and excellent physicochemical properties limit the reviewed materials to biodegradable polyesters and modified compositions of starch and cellulose, both known for their abundance and relatively low price. The addition of different nanofillers and preparation of polymer nanocomposites can effectively improve BP with controlled functional properties and change the rate of degradation. The lack of data on the durability of biodegradable polymer nanocomposites (BPN) has been the motivation for the current review that summarizes recent literature data on environmental ageing of BPN and the role of nanofillers, their basic engineering properties and potential applications. Various durability tests discussed thermal ageing, photo-oxidative ageing, water absorption, hygrothermal ageing and creep testing. It was discussed that incorporating nanofillers into BP could attenuate the loss of mechanical properties and improve durability. Although, in the case of poor dispersion, the addition of the nanofillers can lead to even faster degradation, depending on the structural integrity and the state of interfacial adhesion. Selected models that describe the durability performance of BPN were considered in the review. These can be applied as a practical tool to design BPN with tailored property degradationand durability.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    URL: Article
    DOI: 10.3390/polym13193375
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
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  • 9
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    Online Resource
    UV-Light Curing of 3D Printing Inks from Vegetable Oils for Stereolithography
    MDPI AG ; 2021
    In:  Polymers Vol. 13, No. 8 ( 2021-04-07), p. 1195-
    Details
    In: Polymers, MDPI AG, Vol. 13, No. 8 ( 2021-04-07), p. 1195-
    Abstract: Typical resins for UV-assisted additive manufacturing (AM) are prepared from petroleum-based materials and therefore do not contribute to the growing AM industry trend of converting to sustainable bio-based materials. To satisfy society and industry’s demand for sustainability, renewable feedstocks must be explored; unfortunately, there are not many options that are applicable to photopolymerization. Nevertheless, some vegetable oils can be modified to be suitable for UV-assisted AM technologies. In this work, extended study, through FTIR and photorheology measurements, of the UV-curing of epoxidized acrylate from soybean oil (AESO)-based formulations has been performed to better understand the photopolymerization process. The study demonstrates that the addition of appropriate functional comonomers like trimethylolpropane triacrylate (TMPTA) and the adjusting of the concentration of photoinitiator from 1% to 7% decrease the needed UV-irradiation time by up to 25%. Under optimized conditions, the optimal curing time was about 4 s, leading to a double bond conversion rate (DBC%) up to 80% and higher crosslinking density determined by the Flory–Rehner empirical approach. Thermal and mechanical properties were also investigated via TGA and DMA measurements that showed significant improvements of mechanical performances for all formulations. The properties were improved further upon the addition of the reactive diluents. After the thorough investigations, the prepared vegetable oil-based resin ink formulations containing reactive diluents were deemed suitable inks for UV-assisted AM, giving their appropriate viscosity. The validation was done by printing different objects with complex structures using a laser based stereolithography apparatus (SLA) printer.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    URL: Article
    DOI: 10.3390/polym13081195
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
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  • 10
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    Online Resource
    Highly Loaded Cellulose/Poly (butylene succinate) Sustainable Composites for Woody-Like Advanced Materials Application
    MDPI AG ; 2019
    In:  Molecules Vol. 25, No. 1 ( 2019-12-28), p. 121-
    Details
    In: Molecules, MDPI AG, Vol. 25, No. 1 ( 2019-12-28), p. 121-
    Abstract: We report the manufacturing and characterization of poly (butylene succinate) (PBS) and micro cellulose (MCC) woody-like composites. These composites can be applied as a sustainable woody-like composite alternative to conventional fossil polymer-based wood-plastic composites (WPC). The PBS/MCC composites were prepared by using a melt blending of 70 wt% of MCC processed from bleached softwood. MCC was modified to enhance dispersion and compatibility by way of carbodiimide (CDI), polyhydroxy amides (PHA), alkyl ester (EST), (3-Aminopropyl) trimethoxysilane (APTMS), maleic acid anhydride (MAH), and polymeric diphenylmethane diisocyanate (PMDI). The addition of filler into PBS led to a 4.5-fold improvement of Young’s modulus E for the MCC composite, in comparison to neat PBS. The 1.6-fold increase of E was obtained for CDI modified composition in comparison to the unmodified MCC composite. At room temperature, the storage modulus E′ was found to improve by almost 4-fold for the APTMS composite. The EST composite showed a pronounced enhancement in viscoelasticity properties due to the introduction of flexible long alkyl chains in comparison to other compositions. The glass transition temperature was directly affected by the composition and its value was −15 °C for PBS, −30 °C for EST, and −10 °C for MAH composites. FTIR indicated the generation of strong bonding between the polymer and cellulose components in the composite. Scanning electron microscopy analysis evidenced the agglomeration of the MCC in the PBS/MCC composites. PMDI, APTMS, and CDI composites were characterized by the uniform dispersion of MCC particles and a decrease of polymer crystallinity. MCC chemical modification induced the enhancement of the thermal stability of MCC composites.
    Type of Medium: Online Resource
    ISSN: 1420-3049
    URL: Article
    DOI: 10.3390/molecules25010121
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2008644-1
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