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Graupner N, Müssig J. A Bio-Inspired Approach to Improve the Toughness of Brittle Bast Fibre-Reinforced Composites Using Cellulose Acetate Foils. Biomimetics (Basel) 2024; 9:131. [PMID: 38534816 DOI: 10.3390/biomimetics9030131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/14/2024] [Accepted: 02/17/2024] [Indexed: 03/28/2024] Open
Abstract
Bast fibre-reinforced plastics are characterised by good strength and stiffness but are often brittle due to the stiff and less ductile fibres. This study uses a biomimetic approach to improve impact strength. Based on the structure of the spicules of a deep-sea glass sponge, in which hard layers of bioglass alternate with soft layers of proteins, the toughness of kenaf/epoxy composites was significantly improved by a multilayer structure of kenaf and cellulose acetate (CA) foils as impact modifiers. Due to the alternating structure, cracks are deflected, and toughness is improved. One to five CA foils were stacked with kenaf layers and processed to composite plates with bio-based epoxy resin by compression moulding. Results have shown a significant improvement in toughness using CA foils due to increased crack propagation. The unnotched Charpy impact strength increased from 9.0 kJ/m2 of the pure kenaf/epoxy composite to 36.3 kJ/m2 for the sample containing five CA foils. The tensile and flexural strength ranged from 74 to 81 MPa and 112 to 125 MPa, respectively. The tensile modulus reached values between 9100 and 10,600 MPa, and the flexural modulus ranged between 7200 and 8100 MPa. The results demonstrate the successful implementation of an abstract transfer of biological role models to improve the toughness of brittle bast fibre-reinforced plastics.
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Affiliation(s)
- Nina Graupner
- HSB-Hochschule Bremen, the Biological Materials Group, Department of Biomimetics, Neustadtswall 30, D-28199 Bremen, Germany
| | - Jörg Müssig
- HSB-Hochschule Bremen, the Biological Materials Group, Department of Biomimetics, Neustadtswall 30, D-28199 Bremen, Germany
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Lazarus BS, Leung V, Luu RK, Wong MT, Ruiz-Pérez S, Barbosa WT, Bezerra WBA, Barbosa JDV, Meyers MA. Jackfruit: Composition, structure, and progressive collapsibility in the largest fruit on the Earth for impact resistance. Acta Biomater 2023; 166:430-446. [PMID: 37121367 DOI: 10.1016/j.actbio.2023.04.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/17/2023] [Accepted: 04/26/2023] [Indexed: 05/02/2023]
Abstract
The jackfruit is the largest fruit on the Earth, reaching upwards of 35 kg and falling from heights of 25 m. To survive such high energy impacts, it has evolved a unique layered configuration with a thorny exterior and porous tubular underlayer. During compression, these layers exhibit a progressive collapse mechanism where the tubules are first to deform, followed by the thorny exterior, and finally the mesocarp layer in between. The thorns are composed of lignified bundles which run longitudinally from the base of the thorn to the tip and are embedded in softer parenchymal cells, forming a fiber reinforced composite. The mesocarp contains more lignin than any of the other layers while the core appears to contain more pectin giving rise to variations in compressive and viscoelastic properties between the layers. The surface thorns provide a compelling impact-resistant feature for bioinspiration, with a cellular structure that can withstand large deformation without failing and wavy surface features which densify during compression without fracturing. Even the conical shape of the thorns is valuable, presenting a gradually increasing surface area during axial collapse. A simplified model of this mechanism is put forward to describe the force response of these features. The thorns also distribute damage laterally during impact and deflect cracks along their interstitial valleys. These phenomena were observed in 3D printed, jackfruit-inspired designs which performed markedly better than control prints with the same mass. STATEMENT OF SIGNIFICANCE: Many biological materials have evolved remarkable structures that enhance their mechanical performance and serve as sources of inspiration for engineers. Plants are often overlooked in this regard yet certain botanical components, like nuts and fruit, have shown incredible potential as blueprints for improved impact resistant designs. The jackfruit is the largest fruit on Earth and generates significant falling impact energies. Here, we explore the jackfruit's structure and its mechanical capabilities for the first time. The progressive failure imparted by its multilayered design and the unique collapse mode of the surface thorns are identified as key mechanisms for improving the fruit's impact resistance. 3D printing is used to show that these structure-property benefits can be successfully transferred to engineering materials.
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Affiliation(s)
- Benjamin S Lazarus
- Materials Science and Engineering Program, University of California San Diego, USA.
| | - Victor Leung
- Department of Mechanical and Aerospace Engineering, University of California San Diego, USA
| | - Rachel K Luu
- Department of Mechanical and Aerospace Engineering, University of California San Diego, USA; Department of Materials Science and Engineering, Massachusetts Institute of Technology, USA
| | - Matthew T Wong
- Department of Nanoengineering, University of California San Diego, USA
| | - Samuel Ruiz-Pérez
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Willams T Barbosa
- Department of Materials, University Center SENAI CIMATEC, Salvador, Brazil
| | - Wendell B Almeida Bezerra
- Department of Materials Science, Military Institute of Engineering-IME, Rio de Janeiro 22290270, Brazil
| | | | - Marc A Meyers
- Materials Science and Engineering Program, University of California San Diego, USA; Department of Mechanical and Aerospace Engineering, University of California San Diego, USA; Department of Nanoengineering, University of California San Diego, USA
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Liu F, Wang Z, Guo H, Li H, Chen Y, Guan S. A Double-Layer Hydrogel Dressing with High Mechanical Strength and Water Resistance Used for Drug Delivery. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020499. [PMID: 36677557 PMCID: PMC9864262 DOI: 10.3390/molecules28020499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/22/2022] [Accepted: 12/24/2022] [Indexed: 01/06/2023]
Abstract
Hydrogel dressings provide a moist wound healing environment, absorb the exudates of the wound, and have better biocompatibility than traditional dressings. However, it is still difficult to meet the needs of modern medicine due to the defects in drug burst release, weak mechanical strength, and poor water retention. To solve these problems, we developed a double-layer (DL) hydrogel based on β-cyclodextrin polymer (β-CDP), poly(vinyl alcohol) (PVA), and carboxymethyl cellulose sodium (CMC) via a layer-by-layer method. Inspired by natural coconut, this hydrogel consisted of a drug release layer (DRL) and a mechanical support layer (MSL). In our design, the introduction of β-CDP into the DRL slowed the drug release rate of the DL hydrogel. Furthermore, the mechanical strength of the hydrogel was improved by immersing the MSL in a calcium chloride/boric acid solution. Combining these two layers, the tensile strength and elongation at break of the DL hydrogel reached 1504 kPa and 400%, respectively. More interestingly, the release mechanism of DL hydrogel conformed to the diffusion-relaxation-erosion model, which was different from traditional hydrogel dressings. Therefore, the as-prepared DL structure represents a feasible solution for fabricating high-performance mechanical hydrogel dressings with sustained drug release properties, and the DL hydrogel has potential to be used for medical dressings applied in daily life.
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Affiliation(s)
- Fangzhe Liu
- School of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China
- Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, China
| | - Zihan Wang
- School of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China
| | - Hui Guo
- School of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China
- Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, China
| | - Haichao Li
- School of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China
- Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, China
| | - Yulan Chen
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Shuang Guan
- School of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China
- Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, China
- Correspondence: ; Tel.: +86-133-1430-2303
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Sonego M, Sciuti VF, Vargas R, Canto RB, Pessan LA. Composite design bioinspired by the mesocarp of Brazil nut ( Bertholletia excelsa). BIOINSPIRATION & BIOMIMETICS 2022; 17:046011. [PMID: 35552274 DOI: 10.1088/1748-3190/ac6f37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
The mesocarp ofBertholletia excelsais a rich source of inspiration for strong, stiff and damage-tolerant composites. The bioinspired composites developed here are composed of an epoxy matrix with a 3D printed polylactic acid reinforced with 30% of carbon fiber (PLA-30CF) inspired in fibers, and syntactic foam inspired by sclereids. Monotonic and cyclic four-point bending tests and compact tension fracture toughness tests were carried out assisted by digital image correlation (DIC) to evaluate flexural properties, damage tolerance, and theR-curve of the composite. Its microstructure and fracture surface were analyzed by scanning electron microscopy. The mechanical performance of the bioinspired composite is promising: density of 1.0 g cm-3, flexural apparent elastic modulus of 1.6 GPa, and flexural strength six times higher than the neat epoxy, i.e. 17 MPa. Although the PLA-30CF printed structure led to a risingR-curve, the syntactic foam needs optimization to have a synergistic effect.
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Affiliation(s)
- M Sonego
- Graduate Program in Materials Science and Engineering (PPGCEM), Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
- Mechanical Engineering Institute, Federal University of Itajubá (UNIFEI), Itajubá, MG, Brazil
| | - V F Sciuti
- Graduate Program in Materials Science and Engineering (PPGCEM), Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
- Department of Materials Engineering (DEMa), Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
| | - R Vargas
- Graduate Program in Materials Science and Engineering (PPGCEM), Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
- Université Paris-Saclay, CentraleSupélec, ENS Paris-Saclay, CNRS, LMPS - Laboratoire de Mécanique Paris-Saclay, Gif-sur-Yvette, France
| | - R B Canto
- Graduate Program in Materials Science and Engineering (PPGCEM), Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
- Department of Materials Engineering (DEMa), Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
| | - L A Pessan
- Graduate Program in Materials Science and Engineering (PPGCEM), Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
- Department of Materials Engineering (DEMa), Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
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Graupner N, Lehmann KH, Weber DE, Hilgers HW, Bell EG, Walenta I, Berger L, Brückner T, Kölzig K, Randerath H, Bruns A, Frank B, Wonneberger M, Joulian M, Bruns L, von Dungern F, Janßen A, Gries T, Kunst S, Müssig J. Novel Low-Twist Bast Fibre Yarns from Flax Tow for High-Performance Composite Applications. MATERIALS (BASEL, SWITZERLAND) 2020; 14:E105. [PMID: 33383738 PMCID: PMC7795702 DOI: 10.3390/ma14010105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 11/17/2022]
Abstract
The use of natural fibres for components subjected to higher mechanical requirements tends to be limited by the high price of high-quality semi-finished products. Therefore, the present study deals with the development of more cost-effective staple fibre yarns made from flax tow. In the subsequent processing stage, the yarns were processed into quasi-unidirectional (UD) fabrics. The results of the fibre characterisation along the process chain have shown that no significant mechanical fibre damage occurs after slivers' production. Fibres prepared from yarns and fabrics show comparable characteristics. The yarns were processed to composites by pultrusion to verify the reinforcement effect. The mechanical properties were comparable to those of composites made from a high-quality UD flax roving. The fabrics were industrially processed into composite laminates using a vacuum infusion and an autoclave injection process (vacuum injection method in an autoclave). While impact strength compared to a reference laminate based on the UD flax roving was achieved, tensile and flexural properties were not reached. An analysis showed that the staple fibre yarns in the fabric show an undulation, leading to a reorientation of the fibres and lower characteristic values, which show 86-92% of the laminate made from the flax roving. Hybrid laminates with outer glass and inner flax layers were manufactured for the intended development of a leaf spring for the bogie of a narrow-gauge railroad as a demonstrator. The hybrid composites display excellent mechanical properties and showed clear advantages over a pure glass fibre-reinforced composite in lightweight construction potential, particularly flexural stiffness.
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Affiliation(s)
- Nina Graupner
- The Biological Materials Group, Department of Biomimetics, HSB–City University of Applied Sciences, Neustadtswall 30, D-28199 Bremen, Germany;
| | - Karl-Heinz Lehmann
- Institut für Textiltechnik of RWTH Aachen University, Otto-Blumenthal Straße 1, D-52074 Aachen, Germany; (K.-H.L.); (E.G.B.); (H.R.); (A.J.); (T.G.)
| | - David E. Weber
- The Biological Materials Group, Department of Biomimetics, HSB–City University of Applied Sciences, Neustadtswall 30, D-28199 Bremen, Germany;
| | - Hans-Willi Hilgers
- Wenzel & Hoos GmbH, Berliner Straße 35, D-36304 Alsfeld-Leusel, Germany; (H.-W.H.); (S.K.)
| | - Erik G. Bell
- Institut für Textiltechnik of RWTH Aachen University, Otto-Blumenthal Straße 1, D-52074 Aachen, Germany; (K.-H.L.); (E.G.B.); (H.R.); (A.J.); (T.G.)
| | - Isabel Walenta
- INVENT GmbH, Christian-Pommer-Straße 47, D-38112 Braunschweig, Germany; (I.W.); (M.W.); (M.J.); (F.v.D.)
| | - Luisa Berger
- NOVACOM Verstärkte Kunststoffe GmbH, Werkstraße 26, D-52076 Aachen, Germany; (L.B.); (A.B.); (L.B.)
| | - Torsten Brückner
- SachsenLeinen GmbH, August-Bebel-Straße 2, D-04416 Markkleeberg, Germany; (T.B.); (K.K.)
| | - Kay Kölzig
- SachsenLeinen GmbH, August-Bebel-Straße 2, D-04416 Markkleeberg, Germany; (T.B.); (K.K.)
| | - Herbert Randerath
- Institut für Textiltechnik of RWTH Aachen University, Otto-Blumenthal Straße 1, D-52074 Aachen, Germany; (K.-H.L.); (E.G.B.); (H.R.); (A.J.); (T.G.)
| | - Albert Bruns
- NOVACOM Verstärkte Kunststoffe GmbH, Werkstraße 26, D-52076 Aachen, Germany; (L.B.); (A.B.); (L.B.)
| | - Bernd Frank
- BAFA neu GmbH, Stephanstraße 2, D-76316 Malsch, Germany;
| | - Maik Wonneberger
- INVENT GmbH, Christian-Pommer-Straße 47, D-38112 Braunschweig, Germany; (I.W.); (M.W.); (M.J.); (F.v.D.)
| | - Marc Joulian
- INVENT GmbH, Christian-Pommer-Straße 47, D-38112 Braunschweig, Germany; (I.W.); (M.W.); (M.J.); (F.v.D.)
| | - Lisa Bruns
- NOVACOM Verstärkte Kunststoffe GmbH, Werkstraße 26, D-52076 Aachen, Germany; (L.B.); (A.B.); (L.B.)
| | - Friedrich von Dungern
- INVENT GmbH, Christian-Pommer-Straße 47, D-38112 Braunschweig, Germany; (I.W.); (M.W.); (M.J.); (F.v.D.)
| | - Alexander Janßen
- Institut für Textiltechnik of RWTH Aachen University, Otto-Blumenthal Straße 1, D-52074 Aachen, Germany; (K.-H.L.); (E.G.B.); (H.R.); (A.J.); (T.G.)
| | - Thomas Gries
- Institut für Textiltechnik of RWTH Aachen University, Otto-Blumenthal Straße 1, D-52074 Aachen, Germany; (K.-H.L.); (E.G.B.); (H.R.); (A.J.); (T.G.)
| | - Stefan Kunst
- Wenzel & Hoos GmbH, Berliner Straße 35, D-36304 Alsfeld-Leusel, Germany; (H.-W.H.); (S.K.)
| | - Jörg Müssig
- The Biological Materials Group, Department of Biomimetics, HSB–City University of Applied Sciences, Neustadtswall 30, D-28199 Bremen, Germany;
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Jafarpour M, Eshghi S, Darvizeh A, Gorb S, Rajabi H. Functional significance of graded properties of insect cuticle supported by an evolutionary analysis. J R Soc Interface 2020; 17:20200378. [PMID: 32674704 DOI: 10.1098/rsif.2020.0378] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The exoskeleton of nearly all insects consists of a flexible core and a stiff shell. The transition between these two is often characterized by a gradual change in the stiffness. However, the functional significance of this stiffness gradient is unknown. Here by combining finite-element analysis and multi-objective optimization, we simulated the mechanical response of about 3000 unique gradients of the elastic modulus to normal contacts. We showed that materials with exponential gradients of the elastic modulus could achieve an optimal balance between the load-bearing capacity and resilience. This is very similar to the elastic modulus gradient observed in insect cuticle and, therefore, suggests cuticle adaptations to applied mechanical stresses; this is likely to facilitate the function of insect cuticle as a protective barrier. Our results further indicate that the relative thickness of compositionally different regions in insect cuticle is similar to the optimal estimation. We expect our findings to inform the design of engineered materials with improved mechanical performance.
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Affiliation(s)
- M Jafarpour
- Institute of Zoology, Functional Morphology and Biomechanics, Kiel University, Kiel, Germany.,Faculty of Mechanical Engineering, University of Guilan, Rasht, Iran
| | - Sh Eshghi
- Institute of Zoology, Functional Morphology and Biomechanics, Kiel University, Kiel, Germany
| | - A Darvizeh
- Faculty of Mechanical Engineering, University of Guilan, Rasht, Iran
| | - S Gorb
- Institute of Zoology, Functional Morphology and Biomechanics, Kiel University, Kiel, Germany
| | - H Rajabi
- Institute of Zoology, Functional Morphology and Biomechanics, Kiel University, Kiel, Germany
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Melelli A, Arnould O, Beaugrand J, Bourmaud A. The Middle Lamella of Plant Fibers Used as Composite Reinforcement: Investigation by Atomic Force Microscopy. Molecules 2020; 25:E632. [PMID: 32024088 PMCID: PMC7038022 DOI: 10.3390/molecules25030632] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/27/2020] [Accepted: 01/29/2020] [Indexed: 02/07/2023] Open
Abstract
Today, plant fibers are considered as an important new renewable resource that can compete with some synthetic fibers, such as glass, in fiber-reinforced composites. In previous works, it was noted that the pectin-enriched middle lamella (ML) is a weak point in the fiber bundles for plant fiber-reinforced composites. ML is strongly bonded to the primary walls of the cells to form a complex layer called the compound middle lamella (CML). In a composite, cracks preferentially propagate along and through this layer when a mechanical loading is applied. In this work, middle lamellae of several plant fibers of different origin (flax, hemp, jute, kenaf, nettle, and date palm leaf sheath), among the most used for composite reinforcement, are investigated by atomic force microscopy (AFM). The peak-force quantitative nanomechanical property mapping (PF-QNM) mode is used in order to estimate the indentation modulus of this layer. AFM PF-QNM confirmed its potential and suitability to mechanically characterize and compare the stiffness of small areas at the micro and nanoscale level, such as plant cell walls and middle lamellae. Our results suggest that the mean indentation modulus of ML is in the range from 6 GPa (date palm leaf sheath) to 16 GPa (hemp), depending on the plant considered. Moreover, local cell-wall layer architectures were finely evidenced and described.
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Affiliation(s)
- Alessia Melelli
- IRDL, Université de Bretagne Sud, UMR CNRS 6027, 56321 Lorient, France;
| | - Olivier Arnould
- LMGC, Université de Montpellier, CNRS, 34095 Montpellier, France;
| | - Johnny Beaugrand
- INRAE, UR1268 BIA Biopolymères Interactions Assemblages, 44316 Nantes, France;
| | - Alain Bourmaud
- IRDL, Université de Bretagne Sud, UMR CNRS 6027, 56321 Lorient, France;
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Eshghi SH, Jafarpour M, Darvizeh A, Gorb SN, Rajabi H. A simple, high-resolution, non-destructive method for determining the spatial gradient of the elastic modulus of insect cuticle. J R Soc Interface 2019; 15:rsif.2018.0312. [PMID: 30158184 DOI: 10.1098/rsif.2018.0312] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 08/07/2018] [Indexed: 01/29/2023] Open
Abstract
Nature has evolved structures with high load-carrying capacity and long-term durability. The principles underlying the functionality of such structures, if studied systematically, can inspire the design of more efficient engineering systems. An important step in this process is to characterize the material properties of the structure under investigation. However, direct mechanical measurements on small complex-shaped biological samples involve numerous technical challenges. To overcome these challenges, we developed a method for estimation of the elastic modulus of insect cuticle, the second most abundant biological composite in nature, through simple light microscopy. In brief, we established a quantitative link between the autofluorescence of different constituent materials of insect cuticle, and the resulting mechanical properties. This approach was verified using data on cuticular structures of three different insect species. The method presented in this study allows three-dimensional visualisation of the elastic modulus, which is impossible with any other available technique. This is especially important for precise finite-element modelling of cuticle, which is known to have spatially graded properties. Considering the simplicity, ease of implementation and high-resolution of the results, our method is a crucial step towards a better understanding of material-function relationships in insect cuticle, and can potentially be adapted for other graded biological materials.
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Affiliation(s)
- S H Eshghi
- Department of Mechanical Engineering, Ahrar Institute of Technology and Higher Education, Rasht, Iran
| | - M Jafarpour
- Department of Mechanical Engineering, University of Guilan, Rasht, Iran
| | - A Darvizeh
- Department of Mechanical Engineering, University of Guilan, Rasht, Iran
| | - S N Gorb
- Institute of Zoology, Functional Morphology and Biomechanics, Kiel University, Kiel, Germany
| | - H Rajabi
- Institute of Zoology, Functional Morphology and Biomechanics, Kiel University, Kiel, Germany
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Abstract
The present study focuses on a comparison between different cellulose fiber-reinforced thermoplastics. Composites were produced with 30 mass-% lyocell fibers and a PLA or PP matrix with either an injection (IM) or compression molding (CM) process. Significant reinforcement effects were achieved for tensile strength, Young’s modulus, and Shore D hardness by using lyocell as reinforcing fiber. These values are significantly higher for PLA and its composites compared to PP and PP-based composites. Investigations of the fiber/matrix adhesion show a better bonding for lyocell in PLA compared to PP, resulting in a more effective load transfer from the matrix to the fiber. However, PLA is brittle while PP shows a ductile stress-strain behavior. The impact strength of PLA was drastically improved by adding lyocell while the impact strength of PP decreased. CM and IM composites do not show significant differences in fiber orientation. Despite a better compaction of IM composites, higher tensile strength values were achieved for CM samples due to a higher fiber length.
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