GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 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
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    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
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    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
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    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
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    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
    detail.hit.zdb_id: 2527146-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 6
    Online Resource
    Online Resource
    Multilayered Composites with Carbon Nanotubes for Electromagnetic Shielding Application
    MDPI AG ; 2023
    In:  Polymers Vol. 15, No. 4 ( 2023-02-20), p. 1053-
    Details
    In: Polymers, MDPI AG, Vol. 15, No. 4 ( 2023-02-20), p. 1053-
    Abstract: Bulk polylactic acid (PLA)/multiwall carbon nanotube (MWCNT) composites were prepared and investigated in wide frequency ranges (20 Hz–1 MHz and 24–40 GHz). It was determined that the percolation threshold in bulk PLA/MWCNT composites is close to 0.2 vol.% MWCNT. However, the best microwave dielectric properties and absorption were observed in composites with 3.0–5.0 vol.% MWCNT. Therefore, for future investigations, we selected layered (laminate) polymeric structures with gradual changes in MWCNT concentration from 0.2 to 8.0 vol.% MWCNT. Two approaches to laminate structure designs were examined and compared: a five-layer composite and a nine-layer composite that included four pure PLA middle layers. The addition of MWCNT enhanced the elastic modulus by up to 1.4-fold and tensile strength by up to 1.2-fold, with the best performance achieved at 5.0 vol.% loading. High microwave shielding was observed for these layered PLA/MWCNT structures with a gradient change in MWCNT concentration (up to 26 dB in both transmission and absorption coefficients) in the broad frequency range (from 24 to 40 GHz). Obtained structures are highly anisotropic, and the absorption coefficient is 2–5 dB higher in the direction of MWCNT concentration increase; however, the transmission coefficient is the same in both directions. The properties of microwave absorption are mainly unaffected by the additional polymeric layers. The absorption of the layered structure is greater than the absorption of single-layer composites with an optimal MWCNT concentration of the same thickness. The proposed laminate structure design is promising in the field of efficient electromagnetic shielding.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    URL: Article
    DOI: 10.3390/polym15041053
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2527146-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 7
    Online Resource
    Online Resource
    Cellulose Nanocrystals vs. Cellulose Nanofibers: A Comparative Study of Reinforcing Effects in UV-Cured Vegetable Oil Nanocomposites
    MDPI AG ; 2021
    In:  Nanomaterials Vol. 11, No. 7 ( 2021-07-09), p. 1791-
    Details
    In: Nanomaterials, MDPI AG, Vol. 11, No. 7 ( 2021-07-09), p. 1791-
    Abstract: There is an opportunity to use nanocellulose as an efficient renewable reinforcing filler for polymer composites. There have been many investigations to prove the reinforcement concept of different nanocellulose sources for thermoplastic and thermoset polymers. The present comparative study highlighted the beneficial effects of selecting cellulose nanofibers (CNFs) and nanocrystals (CNCs) on the exploitation properties of vegetable oil-based thermoset composite materials—thermal, thermomechanical, and structural characteristics. The proposed UV-light-curable resin consists of an acrylated epoxidized soybean oil polymer matrix and two different nanocellulose reinforcements. High loadings of up to 30 wt% of CNFs and CNCs in irradiation-cured vegetable oil-based thermoset composites were reported. Infrared spectroscopy analysis indicated developed hydrogen-bonding interactions between the nanocellulose and polymer matrix. CNCs yielded a homogeneous nanocrystal dispersion, while CNFs revealed a nanofiber agglomeration in the polymer matrix, as shown by scanning electron microscopy. Thermal degradation showed that nanocellulose reduced the maximum degradation temperature by 5 °C for the 30 wt% CNC and CNF nanocomposites. Above the glass transition temperature at 80 °C, the storage modulus values increased 6-fold and 2-fold for the 30 wt% CNC and CNF nanocomposites, respectively. In addition, the achieved reinforcement efficiency factor r value for CNCs was 8.7, which was significantly higher than that of CNFs of 2.2. The obtained nanocomposites with enhanced properties show great potential for applications such as UV-light-processed coatings, adhesives, and additive manufacturing inks.
    Type of Medium: Online Resource
    ISSN: 2079-4991
    URL: Article
    DOI: 10.3390/nano11071791
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2662255-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 8
    Online Resource
    Online Resource
    Comparison of Carbon-Nanoparticle-Filled Poly(Butylene Succinate-co-Adipate) Nanocomposites for Electromagnetic Applications
    MDPI AG ; 2022
    In:  Nanomaterials Vol. 12, No. 20 ( 2022-10-19), p. 3671-
    Details
    In: Nanomaterials, MDPI AG, Vol. 12, No. 20 ( 2022-10-19), p. 3671-
    Abstract: Electrostatic dissipative (ESD), anti-static (AS), and electromagnetic interference (EMI) shielding materials are commonly based on commodity fossil-fuel-based plastics. This, in turn, contributes to ever-growing non-biodegradable plastic pollution. Graphene nanoplatelets (GN), multi-walled carbon nanotubes (MWCNT), nanostructured carbon black (NCB), and amorphous carbon black (CB) were utilized as nanofillers to prepare bio-based and biodegradable poly(butylene succinate-co-adipate) (PBSA) nanocomposites. Solvent-cast composites were prepared with 1.1 to 30.0 vol.% nanoparticle loading. The literature mainly focuses on relatively low loadings; therefore, for this research, filler loadings were increased up to 30 vol.% but the maximum loading for NCB and CB loadings only reached 17.4 vol.% due to a lack of dimensional stability at higher loadings. The composites were characterized using tensile testing, volumetric and surface conductivity measurements, thermal conductivity measurements, dielectric spectroscopy in the microwave region, and transmittance in the terahertz range. Tensile tests showed excellent carbon filler compatibility and enhanced tensile strength for loadings up to 5 vol.% (up to 20 vol.% for MWCNT). The highest thermal conductivity values were reached for the MWCNT filler, with the 30.0 vol.% filled composite reaching 0.756 W/mK (262% increase over PBSA). All fillers were able to produce composites that yielded volume conductivities above 10−10 S/m. Composites with MWCNT, GN, and NCB inclusions above the percolation threshold are suitable for EMI applications in the microwave and THz frequency range.
    Type of Medium: Online Resource
    ISSN: 2079-4991
    URL: Article
    DOI: 10.3390/nano12203671
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2662255-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 9
    Online Resource
    Online Resource
    Hydrothermal Ageing Effect on Reinforcement Efficiency of Nanofibrillated Cellulose/Biobased Poly(butylene succinate) Composites
    MDPI AG ; 2022
    In:  Polymers Vol. 14, No. 2 ( 2022-01-06), p. 221-
    Details
    In: Polymers, MDPI AG, Vol. 14, No. 2 ( 2022-01-06), p. 221-
    Abstract: Nanofibrillated cellulose (NFC) is a sustainable functional nanomaterial known for its high strength, stiffness, and biocompatibility. It has become a key building block for the next-generation of lightweight, advanced materials for applications such as consumer products, biomedical, energy storage, coatings, construction, and automotive. Tunable and predictable durability under environmental impact is required for high performance applications. Bio-based poly (butylene succinate) (PBS) composites containing up to 50% NFC content were designed and aged in distilled water or at high relative humidity (RH98%). PBS/NFC composites are characterized by up to 10-fold increased water absorption capacity and diffusivity and the data are correlated with model calculations. Aged samples exhibited decreased crystallinity and melting temperature. Incorporation of NFC into PBS showed up to a 2.6-fold enhancement of the elastic modulus, although accompanied by a loss of strength by 40% and 8-fold reduction in the strain at failure of maximally loaded composites. Hydrothermal ageing had almost no influence on the tensile characteristics of PBS; however, there were considerable degradation effects in PBS/NFC composites. Altered reinforcement efficiency is manifested through a 3.7-fold decreased effective elastic moduli of NFC determined by applying the Halpin–Tsai model and a proportional reduction of the storage moduli of composites. The adhesion efficiency in composites was reduced by hydrothermal ageing, as measured Puckanszky’s adhesion parameter for the strength, which decreased from 3 to 0.8. For the loss factor, Kubat’s adhesion parameter was increased by an order. PBS filled with 20 wt.% NFC is identified as the most efficient composition, for which negative environmental degradation effects are counterbalanced with the positive reinforcement effect. The PBS matrix can be used to protect the NFC network from water.
    Type of Medium: Online Resource
    ISSN: 2073-4360
    URL: Article
    DOI: 10.3390/polym14020221
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527146-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 10
    Online Resource
    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
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...