scholarly journals Strengthening of Wood-like Materials via Densification and Nanoparticle Intercalation

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 478 ◽  
Author(s):  
David Novel ◽  
Simone Ghio ◽  
Andrea Gaiardo ◽  
Antonino Picciotto ◽  
Vincenzo Guidi ◽  
...  
Keyword(s):  
Interfacial Adhesion ◽  
Structural Modification ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Stress Transfer ◽  
Giant Reed ◽  
Cellulose Microfibrils ◽  
Viable Solution ◽  
The Matrix ◽  
Physical Treatments

Recently, several chemical and physical treatments were developed to improve different properties of wood. Such treatments are applicable to many types of cellulose-based materials. Densification leads the group in terms of mechanical results and comprises a chemical treatment followed by a thermo-compression stage. First, chemicals selectively etch the matrix of lignin and hemicellulose. Then, thermo-compression increases the packing density of cellulose microfibrils boosting mechanical performance. In this paper, in comparison with the state-of-the-art for wood treatments we introduce an additional nano-reinforcemeent on densified giant reed to further improve the mechanical performance. The modified nanocomposite materials are stiffer, stronger, tougher and show higher fire resistance. After the addition of nanoparticles, no relevant structural modification is induced as they are located in the gaps between cellulose microfibrils. Their peculiar positioning could increase the interfacial adhesion energy and improve the stress transfer between cellulose microfibrils. The presented process stands as a viable solution to introduce nanoparticles as new functionalities into cellulose-based natural materials.

scholarly journals Utilization of vegetable fibers for production of reinforced cementitious materials

2018 ◽  
Vol 2 ◽  
pp. 145-154 ◽  
Author(s):  
Viviane Costa Correia ◽  
Sergio Francisco Santos ◽  
Holmer Savastano Jr ◽  
Vanderley Moacyr John
Keyword(s):  
Mechanical Performance ◽  
Stress Transfer ◽  
Cost Effective ◽  
Nanofibrillated Cellulose ◽  
Cementitious Materials ◽  
Vegetable Fibers ◽  
The Matrix ◽  
As Stress ◽  
Hybrid Reinforcement ◽  
Cellulosic Pulp

Vegetable fibers produced from agroindustrial resources in the macro, micro and nanometric scales have been used as reinforcement in cementitious materials. The cellulosic pulp, besides being used as the reinforcing element, is also the processing fiber that is responsible for the filtration system in the Hatcheck method. On the other hand, the nanofibrillated cellulose has the advantage of having good mechanical performance and high specific surface, which contributes to improve the adhesion between fiber and matrix. In the hybrid reinforcement, with micro and nanofibers, the cellulose performs bonding elements with the matrix and acts as stress transfer bridges in the micro and nano-cracking network with the corresponding strengthening and toughening of the cementitious composite. Some strategies are studied to mitigate the degradation of the vegetable fibers used in cost-effective and non-conventional fiber cement, as well as to reach a sustainable fiber cement production. As a practical example, the accelerated carbonation curing at early age is a developing technology to increase the durability of composite materials: it decreases porosity, promotes a higher density in the interface generating a good fiber–matrix adhesion and a better mechanical behavior. Thus, the vegetable fibers are potentially applicable to produce high mechanical performance and sustainable cementitious materials for use in the Civil Construction.

The effect of microfibrils cellulose modified epoxy on the quasi-static and fatigue behaviour of open hole carbon textile composites

2018 ◽  
Vol 52 (24) ◽  
pp. 3365-3380 ◽  
Author(s):  
Valter Carvelli ◽  
Toru Fujii ◽  
Kazuya Okubo
Keyword(s):  
Mechanical Performance ◽  
Fatigue Behaviour ◽  
Textile Composites ◽  
Image Correlation ◽  
Cellulose Microfibrils ◽  
Micro Computed Tomography ◽  
The Matrix ◽  
Open Hole ◽  
Static Tensile ◽  
Modified Epoxy

The extensive experimental investigation aimed to assess the effects of hybrid epoxy resin with micro-fibrillated cellulose on tensile quasi-static and fatigue behaviour of open hole carbon plain weave composites. The hybridization of the matrix allowed an improved damage tolerance of the composite leading to increase of the quasi-static tensile strength and extension of the fatigue life. The enhanced mechanical performance of the notched composites was connected to the bridging effect of cellulose microfibrils preventing or delaying the cracks propagation in the matrix and along the fibres interface. The better distribution of the stress state was assessed by digital image correlation strain maps around the hole and the imparted fatigue damage was analysed by scanning electron microscope and X-ray micro-computed tomography visualizations.

Preparation and Characterization of Polyurethane/Multiwalled Carbon Nanotube Composites

2008 ◽  
Vol 16 (8) ◽  
pp. 501-507 ◽  
Author(s):  
Shuzhong Guo ◽  
Chao Zhang ◽  
Weizhi Wang ◽  
Tianxi Liu ◽  
Wuiwui Chauhari Tjiu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Interfacial Adhesion ◽  
In Situ Polymerization ◽  
Stress Transfer ◽  
Mechanical Analysis ◽  
Mechanical Tests ◽  
Multiwalled Carbon Nanotube ◽  
Multiwalled Carbon ◽  
The Matrix ◽  
Nanotube Composites

Multiwalled carbon nanotube (MWNT)/polyurethane (PU) nanocomposites have been prepared by the combination of in-situ polymerization and solution-casting approach. A homogeneous dispersion of MWNTs throughout PU matrix is observed by scanning electron microscopy on the fracture surfaces of the composites. Strong interfacial adhesion between the MWNTs and the PU matrix, as evidenced by the presence of broken but strongly embedded MWNTs in the matrix, is favorable to stress transfer from polymer matrix to the nanotubes. Mechanical tests (by tensile testing and dynamic mechanical analysis) show that, compared with neat PU, both the Young's modulus and the tensile strength of the composites are significantly improved by about 90%, with incorporating only 1 wt.% MWNTs. And most importantly, the elongation-at-break of PU/carbon nanotube (CNT) composites is greatly improved by about 500%, indicating that the toughness of neat PU is remarkably enhanced by adding CNTs into the matrix. The fine dispersion of CNTs and strong interfacial adhesion between the CNTs with the matrix are responsible for the simultaneous and significant enhancement in the strengthening and toughening of PU matrix. In addition, the thermal stability of PU was also improved after incorporating CNTs into the matrix.

Improved Performance in Monofilament Fiber Reinforced Glass Matrix Composites Through the Use of Fiber Coatings

1989 ◽  
Vol 170 ◽  
Author(s):  
William K. Tredway ◽  
Karl M. Prewo
Keyword(s):  
Interfacial Adhesion ◽  
Glass Matrix ◽  
Mechanical Performance ◽  
Large Diameter ◽  
Matrix Composites ◽  
Auger Analysis ◽  
Composite Fabrication ◽  
The Matrix ◽  
Improved Performance ◽  
Glass Matrix Composites

AbstractThe mechanical performance of glass matrix composites reinforced with large diameter (140 µm) monofilaments has been investigated. Strong interfacial adhesion between uncoated boron monofilaments and the borosilicate glass matrix resulted in composites exhibiting low failure strain and brittle fracture. The use of coated monofilaments improved composite performance considerably by reducing fiber-matrix interfacial adhesion. Auger analysis of the interface indicated that a carbon-rich layer had formed between the monofilament coating and the matrix during composite fabrication

An Energy-Based interpretation of Interfacial Adhesion from Single Fibre Composite Fragmentation Testing

1993 ◽  
Vol 2 (5) ◽  
pp. 096369359300200 ◽  
Author(s):  
H.D. Wagner ◽  
S. Ling
Keyword(s):  
Interfacial Adhesion ◽  
Mechanical Characteristics ◽  
Interfacial Shear Strength ◽  
Fibre Composite ◽  
Stress Transfer ◽  
Single Fibre ◽  
Transfer Length ◽  
Fragmentation Test ◽  
Energy Balance Approach ◽  
Fibre Matrix

An energy balance approach is proposed for the single fibre composite (or fragmentation) test, by which the degree of fibre-matrix bonding is quantified by means of the interfacial energy, rather than the interfacial shear strength, as a function of the fibre geometrical and mechanical characteristics, the stress transfer length, and the debonding length. The validity of the approach is discussed using E-glass fibres embedded in epoxy, both in the dry state and in the presence of hot distilled water.

scholarly journals Preparation of Long Sisal Fiber-Reinforced Polylactic Acid Biocomposites with Highly Improved Mechanical Performance

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1124
Author(s):  
Zhifang Liang ◽  
Hongwu Wu ◽  
Ruipu Liu ◽  
Caiquan Wu
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Mechanical Performance ◽  
Tensile Elongation ◽  
Sisal Fiber ◽  
Fiber Reinforced ◽  
Impact Performance ◽  
The Matrix ◽  
Blending Process ◽  
Extension Direction

Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were prepared by compression molding to explore the effect of long fiber on the mechanical properties of sisal fiber-reinforced composites. As a comparison, random short sisal fiber-reinforced PLA composites (SSFCs) were prepared by open milling and molding. The experimental results show that continuous long sisal fiber/PLA premixes could be successfully obtained from this pre-blending process. It was found that the presence of long sisal fibers could greatly improve the tensile strength of LSFC material along the fiber extension direction and slightly increase its tensile elongation. Continuous long fibers in LSFCs could greatly participate in supporting the load applied to the composite material. However, when comparing the mechanical properties of the two composite materials, the poor compatibility between the fiber and the matrix made fiber’s reinforcement effect not well reflected in SSFCs. Similarly, the flexural performance and impact performance of LSFCs had been improved considerably versus SSFCs.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

scholarly journals Constitutive Models for the Tensile Behaviour of TRM Materials: Literature Review and Experimental Verification

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 700
Author(s):  
Maria Concetta Oddo ◽  
Giovanni Minafò ◽  
Lidia La Mendola
Keyword(s):  
State Of The Art ◽  
Constitutive Models ◽  
Stress Transfer ◽  
Theoretical Models ◽  
Tensile Tests ◽  
Analytical Models ◽  
Tensile Behaviour ◽  
Tensile Response ◽  
Textile Reinforced Mortar ◽  
Inorganic Matrix

In recent years, the scientific community has focused its interest on innovative inorganic matrix composite materials, namely TRM (Textile Reinforced Mortar). This class of materials satisfies the need of retrofitting existing masonry buildings, by keeping the compatibility with the substrate. Different recent studies were addressed to improve the knowledge on their mechanical behaviour and some theoretical models were proposed for predicting the tensile response of TRM strips. However, this task is complex due to the heterogeneity of the constituent materials and the stress transfer mechanism developed between matrix and fabric through the interface in the cracked stage. This paper presents a state-of-the-art review on the existing constitutive models for the tensile behavior of TRM composites. Literature experimental results of tensile tests on TRM coupons are presented and compared with the most relevant analytical models proposed until now. Finally, a new experimental study is presented and its results are used to further verify the reliability of the literature expressions.

scholarly journals Nanocomposites Materials of PLA Reinforced with Nanoclays Using a Masterbatch Technology: A Study of the Mechanical Performance and Its Sustainability

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2133
Author(s):  
Helena Oliver-Ortega ◽  
Josep Tresserras ◽  
Fernando Julian ◽  
Manel Alcalà ◽  
Alba Bala ◽  
...  
Keyword(s):  
Food Packaging ◽  
Mechanical Performance ◽  
Polymeric Materials ◽  
Barrier Properties ◽  
Food Tray ◽  
Environmental Concerns ◽  
Poly Lactic Acid ◽  
The Matrix ◽  
Surface Modified ◽  
Being Moved

Packaging consumes around 40% of the total plastic production. One of the most important fields with high requirements is food packaging. Food packaging products have been commonly produced with petrol polymers, but due to environmental concerns, the market is being moved to biopolymers. Poly (lactic acid) (PLA) is the most promising biopolymer, as it is bio-based and biodegradable, and it is well established in the market. Nonetheless, its barrier properties need to be enhanced to be competitive with other polymers such as polyethylene terephthalate (PET). Nanoclays improve the barrier properties of polymeric materials if correct dispersion and exfoliation are obtained. Thus, it marks a milestone to obtain an appropriate dispersion. A predispersed methodology is proposed as a compounding process to improve the dispersion of these composites instead of common melt procedures. Afterwards, the effect of the polarity of the matrix was analyzing using polar and surface modified nanoclays with contents ranging from 2 to 8% w/w. The results showed the suitability of the predispersed and concentrated compound, technically named masterbatch, to obtain intercalated structures and the higher dispersion of polar nanoclays. Finally, the mechanical performance and sustainability of the prepared materials were simulated in a food tray, showing the best assessment of these materials and their lower fingerprint.

scholarly journals Thermal degradation of hemicellulose and cellulose in ball-milled cedar and beech wood

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Jiawei Wang ◽  
Eiji Minami ◽  
Mohd Asmadi ◽  
Haruo Kawamoto
Keyword(s):  
Thermal Degradation ◽  
Ball Milling ◽  
Cell Walls ◽  
Uronic Acid ◽  
Beech Wood ◽  
Cellulose Microfibrils ◽  
Homogeneous Distribution ◽  
Japanese Beech ◽  
Temperature Range ◽  
The Matrix

AbstractThe thermal degradation reactivities of hemicellulose and cellulose in wood cell walls are significantly different from the thermal degradation behavior of the respective isolated components. Furthermore, the degradation of Japanese cedar (Cryptomeria japonica, a softwood) is distinct from that of Japanese beech (Fagus crenata, a hardwood). Lignin and uronic acid are believed to play crucial roles in governing this behavior. In this study, the effects of ball milling for various durations of time on the degradation reactivities of cedar and beech woods were evaluated based on the recovery rates of hydrolyzable sugars from pyrolyzed wood samples. The applied ball-milling treatment cleaved the lignin β-ether bonds and reduced the crystallinity of cellulose, as determined by X-ray diffraction. Both xylan and glucomannan degraded in a similar temperature range, although the isolated components exhibited different reactivities because of the catalytic effect of uronic acid bound to the xylose chains. These observations can be explained by the more homogeneous distribution of uronic acid in the matrix of cell walls as a result of ball milling. As observed for holocelluloses, cellulose in the ball-milled woods degraded in two temperature ranges (below 320 °C and above); a significant amount of cellulose degraded in the lower temperature range, which significantly changed the shapes of the thermogravimetric curves. This report compares the results obtained for cedar and beech woods, and discusses them in terms of the thermal degradation of the matrix and cellulose microfibrils in wood cell walls and role of lignin. Such information is crucial for understanding the pyrolysis and heat treatment of wood.

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