{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,28]],"date-time":"2026-03-28T02:42:36Z","timestamp":1774665756995,"version":"3.50.1"},"reference-count":41,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2020,10,13]],"date-time":"2020-10-13T00:00:00Z","timestamp":1602547200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["TSSiPRO; NORTE-01-0145-FEDER-000015"],"award-info":[{"award-number":["TSSiPRO; NORTE-01-0145-FEDER-000015"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Cellulose nanocrystals (CNC) have attracted the attention of many engineering fields and offered excellent mechanical and physical properties as polymer reinforcement. However, their application in composite products with high material demand is complex due to the current production costs. This work explores the use of cellulose microfibers (MF) obtained by a straightforward water dispersion of kraft paper to reinforce polyhydroxyalkanoate (PHA) and polylactic acid (PLA) films. To assess the influence of this type of filler material on the properties of biopolymers, films were cast and reinforced at different scales, with both CNC and MF separately, to compare their effectiveness. Regarding mechanical properties, CNC has a better reinforcing effect on the tensile strength of PLA samples, though up to 20 wt.% of MF may also lead to stronger PLA films. Moreover, PHA films reinforced with MF are 23% stronger than neat PHA samples. This gain in strength is accompanied by an increment of the stiffness of the material. Additionally, the addition of MF leads to an increase in the crystallinity of PHA that can be controlled by heat treatment followed by quenching. This change in the crystallinity of PHA affects the hygroscopicity of PHA samples, allowing the modification of the water barrier properties according to the required features. The addition of MF to both types of polymers also increases the surface roughness of the films, which may contribute to obtaining better interlaminar bonding in multi-layer composite applications. Due to the partial lignin content in MF from kraft paper, samples reinforced with MF present a UV blocking effect. Therefore, MF from kraft paper may be explored as a way to introduce high fiber concentrations (up to 20 wt.%) from other sources of recycled paper into biocomposite manufacturing with economic and technical benefits.<\/jats:p>","DOI":"10.3390\/molecules25204653","type":"journal-article","created":{"date-parts":[[2020,10,17]],"date-time":"2020-10-17T07:23:22Z","timestamp":1602919402000},"page":"4653","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":73,"title":["Potential of Cellulose Microfibers for PHA and PLA Biopolymers Reinforcement"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1850-3178","authenticated-orcid":false,"given":"Gonzalo","family":"M\u00e1rmol","sequence":"first","affiliation":[{"name":"Centre for Textile Science and Technology (2C2T), University of Minho, 4800-058 Guimar\u00e3es, Portugal"}]},{"given":"Christian","family":"Gauss","sequence":"additional","affiliation":[{"name":"School of Science and Engineering, University of Waikato, Hamilton 3216, New Zealand"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3303-6563","authenticated-orcid":false,"given":"Raul","family":"Fangueiro","sequence":"additional","affiliation":[{"name":"Centre for Textile Science and Technology (2C2T), University of Minho, 4800-058 Guimar\u00e3es, Portugal"},{"name":"Department of Mechanical Engineering, University of Minho, 4800-058 Guimar\u00e3es, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2020,10,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2518","DOI":"10.1016\/j.matpr.2017.11.034","article-title":"Green composites: A review","volume":"5","author":"Shekar","year":"2018","journal-title":"Mater. Today Proc."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"558","DOI":"10.1016\/j.rser.2017.05.094","article-title":"Plant fibre based bio-composites: Sustainable and renewable green materials","volume":"79","author":"Ramesh","year":"2017","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1920","DOI":"10.1016\/j.compositesb.2011.05.039","article-title":"Mechanical response of PHB and cellulose acetate natural fiber-reinforced composites for construction applications","volume":"42","author":"Christian","year":"2011","journal-title":"Compos. Part B Eng."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"E526","DOI":"10.1002\/app.36852","article-title":"Study on poly (lactic acid)\/natural fibers composites","volume":"125","author":"Zhang","year":"2012","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"156","DOI":"10.2174\/1570179413666160921115245","article-title":"An overview on polylactic acid, its cellulosic composites and applications","volume":"14","author":"Saba","year":"2017","journal-title":"Curr. Org. Synth."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Mathuriya, A.S., Yakhmi, J.V., Mart\u00ednez, L.M.T., Kharissova, O.V., and Kharisov, B.I. (2017). Polyhydroxyalkanoates: Biodegradable plastics and their applications. Handbook of Ecomaterials, Springer.","DOI":"10.1007\/978-3-319-48281-1_84-1"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"791","DOI":"10.3144\/expresspolymlett.2014.82","article-title":"Polyhydroxyalkanoate (PHA): Review of synthesis, characteristics, processing and potential applications in packaging","volume":"8","author":"Bugnicourt","year":"2014","journal-title":"Express Polym. Lett."},{"key":"ref_8","first-page":"1","article-title":"Polyhydroxyalkanoates (PHA) toward cost competitiveness and functionality","volume":"3","author":"Chen","year":"2020","journal-title":"Adv. Ind. Eng. Polym. Res."},{"key":"ref_9","first-page":"10","article-title":"Effect of coupling agent content on properties of composites made from polylactic acid and chrysanthemum waste","volume":"26","author":"Koay","year":"2019","journal-title":"J. Vinyl Addit. Technol."},{"key":"ref_10","unstructured":"Seggiani, M., Cinelli, P., Verstichel, S., Puccini, M., Vitolo, S., Anguillesi, I., and Lazzeri, A. (2015). Development of fibres-reinforced biodegradable composites. Chem. Eng. Trans., 1813\u20131818."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Nery, T.B.R., Dos Santos, Z.I.G., and Jos\u00e9, N.M. (2018). Desenvolvimento e caracteriza\u00e7\u00e3o de biocomp\u00f3sitos de polihidroxibutirato e fibra de bananeira. Mat\u00e9ria Rio Jan., 23.","DOI":"10.1590\/s1517-707620180004.0591"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1590\/S0104-14282010005000011","article-title":"Estudo das propriedades mec\u00e2nicas e t\u00e9rmicas do pol\u00edmero Poli-3-hidroxibutirato (PHB) e de comp\u00f3sitos PHB\/p\u00f3 de madeira","volume":"20","author":"Machado","year":"2010","journal-title":"Pol\u00edmeros"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Shojaeiarani, J., and Bajwa, D. (2018). Functionalized Cellulose Nanocrystals for Improving the Mechanical Properties of Poly (Lactic Acid), American Society of Mechanical Engineers.","DOI":"10.1115\/IMECE2018-87691"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Mokhena, T.C., Sefadi, J.S., Sadiku, E., John, M.J., Mochane, M.J., and Mtibe, A. (2018). Thermoplastic processing of PLA\/cellulose nanomaterials composites. Polymers, 10.","DOI":"10.20944\/preprints201810.0477.v1"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1016\/j.carbpol.2018.10.014","article-title":"PHBV-graft-GMA via reactive extrusion and its use in PHBV\/nanocellulose crystal composites","volume":"205","author":"Zheng","year":"2019","journal-title":"Carbohydr. Polym."},{"key":"ref_16","first-page":"3613","article-title":"Increasing the elongation at break of polyhydroxybutyrate biopolymer: Effect of cellulose nanowhiskers on mechanical and thermal properties","volume":"127","author":"Pereira","year":"2012","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1763","DOI":"10.1039\/C6NR09494E","article-title":"Recent progress in cellulose nanocrystals: Sources and production","volume":"9","author":"Trache","year":"2017","journal-title":"Nanoscale"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Seoane, I.T., Manfredi, L.B., Cyras, V.P., Torre, L., Fortunati, E., and Puglia, D. (2017). Effect of cellulose nanocrystals and bacterial cellulose on disintegrability in composting conditions of plasticized PHB nanocomposites. Polymers, 9.","DOI":"10.3390\/polym9110561"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"858","DOI":"10.3144\/expresspolymlett.2019.75","article-title":"Polylactic acid-lauryl functionalized nanocellulose nanocomposites: Microstructural, thermo-mechanical and gas transport properties","volume":"13","author":"Rigotti","year":"2019","journal-title":"Express Polym. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1007\/s13726-019-00778-4","article-title":"Isothermal cold crystallization kinetics and properties of thermoformed poly (lactic acid) composites: Effects of talc, calcium carbonate, cassava starch and silane coupling agents","volume":"29","author":"Deetuam","year":"2020","journal-title":"Iran. Polym. J."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1007\/s12088-015-0528-6","article-title":"Challenges and opportunities for customizing polyhydroxyalkanoates","volume":"55","author":"Singh","year":"2015","journal-title":"Indian J. Microbiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1317","DOI":"10.1016\/S0266-3538(03)00103-9","article-title":"Natural fibres as reinforcement in polylactic acid (PLA) composites","volume":"63","author":"Oksman","year":"2003","journal-title":"Compos. Sci. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1016\/j.indcrop.2017.01.035","article-title":"Effect of agave fiber content in the thermal and mechanical properties of green composites based on polyhydroxybutyrate or poly (hydroxybutyrate-co-hydroxyvalerate)","volume":"99","year":"2017","journal-title":"Ind. Crops Prod."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"810","DOI":"10.1016\/j.compositesa.2009.04.003","article-title":"Natural and man-made cellulose fibre-reinforced poly (lactic acid) (PLA) composites: An overview about mechanical characteristics and application areas","volume":"40","author":"Graupner","year":"2009","journal-title":"Compos. Part A Appl. Sci. Manuf."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1016\/j.indcrop.2009.08.005","article-title":"Biodegradable composites based on flax\/polyhydroxybutyrate and its copolymer with hydroxyvalerate","volume":"31","author":"Barkoula","year":"2010","journal-title":"Ind. Crops Prod."},{"key":"ref_26","unstructured":"Drioli, E., and Giorno, L. (2014). Annealing of polymer membranes. Encyclopedia of Membranes, Springer."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"125108","DOI":"10.1088\/2053-1591\/ab5755","article-title":"Effect of nano-cellulosic fiber on mechanical and barrier properties of polylactic acid (PLA) green nanocomposite film","volume":"6","author":"Kumar","year":"2019","journal-title":"Mater. Res. Express"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1711","DOI":"10.1021\/acssuschemeng.6b02458","article-title":"Rheological and thermo-mechanical properties of poly (lactic acid)\/lignin-coated cellulose nanocrystal composites","volume":"5","author":"Gupta","year":"2017","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"7203","DOI":"10.1021\/ma049117o","article-title":"Infrared spectroscopy studies of CH\u00b7\u00b7\u00b7O hydrogen bondings and thermal behavior of biodegradable poly (hydroxyalkanoate)","volume":"37","author":"Sato","year":"2004","journal-title":"Macromolecules"},{"key":"ref_30","unstructured":"Socrates, G. (2010). Infrared and Raman Characteristic Group Frequencies: Tables and Charts, Wiley. [3rd ed.]."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"4274","DOI":"10.1021\/ma0501343","article-title":"Conformation rearrangement and molecular dynamics of poly (3-hydroxybutyrate) during the melt-crystallization process investigated by infrared and two-dimensional infrared correlation spectroscopy","volume":"38","author":"Zhang","year":"2005","journal-title":"Macromolecules"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"541","DOI":"10.1016\/j.saa.2004.05.004","article-title":"Melting behavior of poly (3-hydroxybutyrate) investigated by two-dimensional infrared correlation spectroscopy","volume":"61","author":"Padermshoke","year":"2005","journal-title":"Spectrochim. Acta Part A Mol. Biomol. Spectrosc."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1016\/j.carres.2012.07.009","article-title":"A complete characterization of the vibrational spectra of sucrose","volume":"361","author":"Brizuela","year":"2012","journal-title":"Carbohydr. Res."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"433","DOI":"10.1016\/j.ijbiomac.2017.08.036","article-title":"Biodegradable poly (lactic acid)\/Cellulose nanocrystals (CNCs) composite microcellular foam: Effect of nanofillers on foam cellular morphology, thermal and wettability behavior","volume":"106","author":"Borkotoky","year":"2018","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"512","DOI":"10.1016\/j.joei.2018.04.007","article-title":"Study of breakage of main covalent bonds during co-pyrolysis of oil shale and alkaline lignin by TG-FTIR integrated analysis","volume":"92","author":"Bai","year":"2019","journal-title":"J. Energy Inst."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"2157","DOI":"10.1016\/j.ijbiomac.2017.10.089","article-title":"A Statistical approach to optimize the production of Polyhydroxyalkanoates from Wickerhamomyces anomalus VIT-NN01 using response surface methodology","volume":"107","author":"Ojha","year":"2018","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"929","DOI":"10.1007\/s10973-009-0121-5","article-title":"Thermal degradation of poly (lactic acid) measured by thermogravimetry coupled to Fourier transform infrared spectroscopy","volume":"97","author":"Zou","year":"2009","journal-title":"J. Therm. Anal. Calorim."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/S1011-1344(00)00054-3","article-title":"Photo and radiation chemical induced degradation of lignin model compounds","volume":"56","author":"Lanzalunga","year":"2000","journal-title":"J. Photochem. Photobiol. B Biol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1029","DOI":"10.1016\/j.ijbiomac.2019.07.157","article-title":"Utilization of lignin fractions in UV resistant lignin-PLA biocomposites via lignin-lactide grafting","volume":"138","author":"Park","year":"2019","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"320","DOI":"10.1039\/C4GC01333F","article-title":"Lignin: A nature-inspired sun blocker for broad-spectrum sunscreens","volume":"17","author":"Qian","year":"2015","journal-title":"Green Chem."},{"key":"ref_41","first-page":"825","article-title":"Drying of paper: A review 2000\u20132018","volume":"38","year":"2019","journal-title":"Dry. Technol."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/25\/20\/4653\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:20:02Z","timestamp":1760178002000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/25\/20\/4653"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,10,13]]},"references-count":41,"journal-issue":{"issue":"20","published-online":{"date-parts":[[2020,10]]}},"alternative-id":["molecules25204653"],"URL":"https:\/\/doi.org\/10.3390\/molecules25204653","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,10,13]]}}}