scholarly journals Regenerated isotropic wood

2020 ◽  
Author(s):  
Qing-Fang Guan ◽  
Zi-Meng Han ◽  
Huai-Bin Yang ◽  
Zhang-Chi Ling ◽  
Shu-Hong Yu
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Flexural Modulus ◽  
Building Blocks ◽  
Structure Design ◽  
Practical Applications ◽  
Wood Particles ◽  
Natural Wood ◽  
Core Part ◽  
Made In

ABSTRACT Construction of sustainable high-performance structural materials is a core part of the key global sustainability goal. Many efforts have been made in this field; however, challenges remain in terms of lowering costs by using all-green basic building blocks and improving mechanical properties to meet the demand of practical applications. Here, we report a robust and efficient bottom-up strategy with micro/nanoscale structure design to regenerate an isotropic wood from natural wood particles as a high-performance sustainable structural material. Regenerated isotropic wood (RGI-wood) exceeds the limitations of the anisotropic and inconsistent mechanical properties of natural wood, having isotropic flexural strength of ∼170 MPa and flexural modulus of ∼10 GPa. RGI-wood also shows superior water resistance and fire retardancy properties to natural pine wood. Mass production of large sized RGI-wood and functional RGI-wood nanocomposites can also be achieved.

scholarly journals Mechanically Robust Flexible Multilayer Aramid Nanofibers and MXene Film for High-Performance Electromagnetic Interference Shielding and Thermal Insulation

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3041
Author(s):  
Jun Zhou ◽  
Junsheng Yu ◽  
Dongyu Bai ◽  
Huili Liu ◽  
Lu Li
Keyword(s):  
Mechanical Properties ◽  
Composite Film ◽  
Electromagnetic Interference ◽  
Multilayer Structure ◽  
High Performance ◽  
Composite Films ◽  
Next Generation ◽  
Shielding Effectiveness ◽  
Breaking Strain ◽  
Practical Applications

In order to overcome the various defects caused by the limitations of solid metal as a shielding material, the development of electromagnetic shielding materials with flexibility and excellent mechanical properties is of great significance for the next generation of intelligent electronic devices. Here, the aramid nanofiber/Ti3C2Tx MXene (ANF/MXene) composite films with multilayer structure were successfully prepared through a simple alternate vacuum-assisted filtration (AVAF) process. With the intervention of the ANF layer, the multilayer-structure film exhibits excellent mechanical properties. The ANF2/MXene1 composite film exhibits a tensile strength of 177.7 MPa and a breaking strain of 12.6%. In addition, the ANF5/MXene4 composite film with a thickness of only 30 μm exhibits an electromagnetic interference (EMI) shielding efficiency of 37.5 dB and a high EMI-specific shielding effectiveness value accounting for thickness (SSE/t) of 4718 dB·cm2 g−1. Moreover, the composite film was excellent in heat-insulation performance and in avoiding light-to-heat conversion. No burning sensation was produced on the surface of the film with a thickness of only 100 μm at a high temperature of 130 °C. Furthermore, the surface of the film was only mild when touched under simulated sunlight. Therefore, our multilayer-structure film has potential significance in practical applications such as next-generation smart electronic equipment, communications, and military applications.

Structure Design for High Performance n-Type Polymer Thermoelectric Materials

2021 ◽  
Author(s):  
Qi Zhang ◽  
Hengda Sun ◽  
Meifang Zhu
Keyword(s):  
Conjugated Polymers ◽  
Thermoelectric Materials ◽  
High Performance ◽  
Waste Heat ◽  
Building Blocks ◽  
Structure Design ◽  
Potential Candidate ◽  
Polymer Backbone ◽  
P Type ◽  
Polymer Thermoelectric

Abstract Organic thermoelectric (OTE) materials have been regarded as a potential candidate to harvest waste heat from complex, low temperature surfaces of objects and convert it into electricity. Recently, n-type conjugated polymers as organic thermoelectric materials have aroused intensive research in order to improve their performance to match up with their p-type counterpart. In this review, we discuss aspects that affect the performance of n-type OTEs, and further focus on the effect of planarity of backbone on doping efficiency and eventually the TE performance. We then summarize strategies such as implementing rigid n-type polymer backbone or modifying conventional polymer building blocks for more planar conformation. In the outlook part, we conclude forementioned devotions and point out new possibility that may promote the future development of this field.

Volumetric Changes of the UHPC Matrix and its Determination

2016 ◽  
Vol 827 ◽  
pp. 215-218 ◽  
Author(s):  
David Čítek ◽  
Milan Rydval ◽  
Jiří Kolísko
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
Experimental Tests ◽  
Structure Design ◽  
Ultra High Performance Concrete ◽  
Fine Grained ◽  
Durability Properties ◽  
Shrinkage And Creep

Research in the Ultra-High Performance Concrete applications field is very important. Current experiences shows that the structure design should be optimize due to relatively new fine-grained cement-based Hi-Tech material with excellent mechanical and durability properties. It is not sure if some of the volumetric changes like creep or shrinkage has or has not an impact on an advantage for the construction and for the structure design. The effect of the shrinkage and creep of common used concretes are well known and well described at publications but the effect of volumetric changes of the UHPC is mostly unknown because of the fact that some of experimental tests are long term and the development of UHPC is still in its basics. A lot of works are focused on a basic mechanical properties and durability tests.

Mechanical properties of wood flour/poly (lactic acid) composites coupled with waterborne silane-polyacrylate copolymer emulsion

Holzforschung ◽  
2016 ◽  
Vol 70 (5) ◽  
pp. 439-447 ◽  
Author(s):  
Ru Liu ◽  
Shupin Luo ◽  
Jinzhen Cao ◽  
Yu Chen
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
High Performance ◽  
Coupling Effect ◽  
Wood Flour ◽  
Flexural Modulus ◽  
Coupling Agents ◽  
Poly Lactic Acid ◽  
Effective Coupling ◽  
Methacryloxypropyl Trimethoxysilane

Abstract Wood flour/polylactic acid (WF/PLA) composites were produced with a WF content of 50% based on three types of waterborne polyacrylate (PA) emulsions including a PA homopolymer emulsion and two types of silane-PA copolymer emulsions as coupling agents. Two silanes were in focus, namely, γ-methacryloxypropyl- trimethoxysilane (silane-1) and vinyltrimethoxysilane (silane-2). The emulsions and the modified WFs were characterized, and the effects were investigated in terms of emulsion type and their loading levels on the mechanical properties of WF/PLA composites. (1) Both types of silanes could be successfully copolymerized with PA to form stable emulsions. (2) With increasing PA loading, the mechanical properties (except for flexural modulus) of the composites increased at first before reaching the maximum values at 4% PA loading and then the properties worsened. However, these values were larger than those of pure composites, especially in cases when PA-silane emulsions were applied. (3) PA modified with silane-1 showed the best coupling effect among all the three PA emulsions. The results can be interpreted that PA emulsions are effective coupling agents for the preparation of high-performance WPCs.

Achieving high-performance epoxy nanocomposites with trifunctional poly(oxypropylene)amines functionalized graphene oxide

2019 ◽  
Vol 31 (5) ◽  
pp. 557-569 ◽  
Author(s):  
Tong Sun ◽  
Huawei Zou ◽  
Ya Zhou ◽  
Rui Li ◽  
Mei Liang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
High Performance ◽  
Flexural Modulus ◽  
Covalent Bonds ◽  
Spectra Analysis ◽  
Functionalized Graphene Oxide ◽  
Ep Matrix ◽  
Functional Graphene Oxide ◽  
The Relationship

In this article, two types of functional graphene oxide (GO) with amine-rich surface were synthesized through chemically grafting two different molecular chain length trifunctional poly(oxypropylene)amines T5000 and T403, which were named as T5000-GO and T403-GO, respectively. The functionalized GO was then added to epoxy (EP) resin. Fourier transform infrared spectra analysis confirmed successful chemical functionalization on GO. Both T403-GO and T5000-GO were tightly embedded in the EP, because the amine-rich surface of functionalized-GO could form covalent bonds with the EP matrix, thereby contributing to the enhancement of mechanical properties. Particularly, T5000-GO, which has longer grafting molecule chains, achieved better compatibility and dispersibility in the EP matrix, resulting in a better reinforcing efficiency in mechanical properties. For example, the T5000-GO/EP composites showed an incremental enhancement in tensile strength with increasing filler concentrations, whereas their T403-GO/EP counterparts failed to follow the same trend. Meanwhile, the T5000-GO/EP composites with only 0.1-wt% T5000-GO achieved a prominent increase in flexural strength (approximately 50%) and flexural modulus (approximately 26.8%), which were higher than those of T403-GO-filled counterparts. This work indicated that the compatibility and interphase between GO and EP could be designed by manipulating the length of grafting molecule chains, thereby providing a better understanding of the relationship between the structure and mechanical properties of the graphene/EP nanocomposites.

An Analysis on the Tensile Strength of Hybridized Reinforcement Filament Yarns by Commingling Process

2007 ◽  
Vol 539-543 ◽  
pp. 974-978
Author(s):  
Chathura Nalendra Herath ◽  
Beong Bok Hwang ◽  
B.S. Ham ◽  
Jung Min Seo ◽  
Bok Choon Kang
Keyword(s):  
Mechanical Properties ◽  
Glass Matrix ◽  
High Performance ◽  
Glass Fibers ◽  
Tensile Force ◽  
Matrix Material ◽  
General Purpose ◽  
Practical Applications ◽  
Advantages And Disadvantages ◽  
Glass Matrices

Carbon, aramid and glass fibers are inherently superior to conventional textile fibers in terms of mechanical properties as well as other chemical characteristics. Because of inherent advantages and disadvantages associated with each material, it is generally better to hybridize them to fully benefit of their high performance in many practical applications. In this paper, the possibility of hybridizing Carbon/Aramid-, Carbon/Glass- and Aramid/Glass- matrices has been investigated through the commingling process. In the experiment, several process parameters were selected and they include pressure, yarn oversupply-rate and different nozzle types. As a result of experiments, it was concluded that the hybridized materials has shown better performance than individual reinforced filament yarns in terms of mechanical properties. For small tensile forces, the Carbon/Glass/matrix combination turned out to be good enough for general purpose applications. However, for high tensile applications, Carbon/Aramid or Aramid/Glass with matrix combinations was better than the other material combinations. The hybridization process was also investigated under an air pressure of 5 bar, a yarn oversupply-rate of 1.5% for reinforced filaments, and 3.5% to 6% for matrix materials, respectively. It was also shown from the experimental results that Carbon/Glass/matrix combination may be desirable for small tensile force applications and Carbon/Aramid/matrix and Glass/Aramid/matrix combinations most suitable for heavy tensile force applications, respectively. As a matrix material, polypropylene and polyester have shown better performance than polyether-ether-keeton in terms of tensile property.

scholarly journals Effect of MWCNT on Thermal, Mechanical, and Morphological Properties of Polybutylene Terephthalate/Polycarbonate Blends

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
C. P. Rejisha ◽  
S. Soundararajan ◽  
N. Sivapatham ◽  
K. Palanivelu
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Flexural Modulus ◽  
Tensile Modulus ◽  
Nucleating Agent ◽  
Mechanical Analysis ◽  
Morphological Properties ◽  
Multiwall Carbon Nanotube ◽  
Polybutylene Terephthalate ◽  
The Impact

This paper evaluated the effect of multiwall carbon nanotube (MWCNT) on the properties of PBT/PC blends. The nanocomposites were obtained by melt blending MWCNT in the weight percentages 0.15, 0.3, and 0.45 wt% with PBT/PC blends in a high performance corotating twin screw extruder. Samples were characterized by tensile testing, dynamic mechanical analysis, thermal analysis, scanning electron microscopy, and X-ray diffraction. Concentrations of PBT and PC are optimized as 80 : 20 based on mechanical properties. A small amount of MWCNT shows better increase in the thermal and mechanical properties of the blends of PBT/PC nanocomposite when compared to nanoclays or inorganic fillers. The ultimate tensile strength of the nanocomposites increased from 54 MPa to 85 MPa with addition of MWCNT up to 0.3% and then decreased.The tensile modulus values were increased to about 60% and the flexural modulus was more than about 80%. The impact strength was also improved with 20% PC to about 60% and with 0.15% MWCNT to about 50%. The HDT also improved from 127°C to 205°C. It can be seen from XRD result that the crystallinity of PBT is less affected by incorporating MWCNT. The crystallizing temperature was increased and the MWCNT may act as a strong nucleating agent.

IM7/LARC™-IAX-3 Polyimide Composites

1998 ◽  
Vol 10 (2) ◽  
pp. 193-206 ◽  
Author(s):  
T H Hou ◽  
T L St Clair
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Elevated Temperatures ◽  
Flexural Modulus ◽  
Longitudinal Tensile Strength ◽  
Molecular Weights ◽  
Short Beam ◽  
Beam Shear ◽  
Carrier Solvent ◽  
Langley Research Center

LARC™-IAX-3 (Langley Research Center™-improved adhesive experimental resin-3) aromatic polyimide, based on oxydiphthalic anhydride, 3,′4-oxydianiline (3,′4-ODA) and 1,4-phenylenediamine ( p-PDA), was evaluated as a matrix for high-performance composites. Four poly(amide acid) solutions in either N-methypyrrolidone or γ-butyrolactone, end-capped with phthalic anhydride to various theoretical molecular weights, were synthesized. Unidirectional prepreg was fabricated from each of the four resins utilizing NASA-Langley’s multipurpose prepreg machine. The temperature-dependent volatile depletion rates, the thermal crystallization behaviour and the resin rheology were characterized. Based on this information, a composite moulding cycle was developed which consistently yielded well consolidated void-free laminate parts. Composite mechanical properties such as short beam shear strength, longitudinal and transverse flexural strength and flexural modulus, longitudinal tensile strength and notched and unnotched compression strengths were measured at room temperature (RT) and elevated temperatures. Similar properties were obtained independent of the carrier solvent used during matrix resin synthesis. These mechanical properties were superior to those previously measured for IM7/LARC™-IA and IM7/LARC™-IAX composites. The enhanced mechanical properties were attributed to the substitution of 25% 3,′4-ODA by p-PDA in the LARC™-IA imide backbones.

A Novel Synthesis Design Approach for Continuous, Inhomogeneous Structures

2007 ◽  
Author(s):  
Or Yogev ◽  
Erik K. Antonsson
Keyword(s):  
Mechanical Properties ◽  
Dna Sequence ◽  
High Performance ◽  
Building Blocks ◽  
Design Synthesis ◽  
Novel Approach ◽  
Gene String ◽  
Artificial Environment ◽  
Artificial Dna ◽  
Rule Sets

This paper presents a novel approach for the design synthesis of continuous inhomogeneous structures. The objective of this research is to mimic biological principles of growth and evolution in order to explore a set of novel design configurations identified by high complexity both in topology and mechanical properties. The ability to synthesize novel structures is explored from an engineering point view, where the use of inhomogeneous properties can increase the ability of a structure to support external loads and minimize weight. Based on the observation that biological structures are inhomogeneous, in the sense that different cells have different properties, an artificial environment has been created which models the biological growth procedure with cells that serve as building blocks of the structure. Cell differentiation is expressed only in the sense of mechanical properties. Each cell contains an identical artificial DNA sequence which is executed during the growth procedure and stops once the structure meets desired engineering requirements, such as supporting loads. The DNA contains sets of rules which are encoded as a gene string. A relatively simple DNA sequence can give rise to complex inhomogeneous structures; small changes in the rules can lead to a significantly different structures with different properties. The representation of these rules is ideally suited for evolution, which will be applied in the future to evolve rule-sets that grow and develop high-performance inhomogeneous structures.

scholarly journals An effective technique for constructing wood composite with superior dimensional stability

Holzforschung ◽  
2020 ◽  
Vol 74 (5) ◽  
pp. 435-443
Author(s):  
Xiaoshuai Han ◽  
Zhenxing Wang ◽  
Qinqin Zhang ◽  
Junwen Pu
Keyword(s):  
Mechanical Properties ◽  
Dimensional Stability ◽  
High Performance ◽  
Low Cost ◽  
Sem Analysis ◽  
Wood Composite ◽  
Engineering Structures ◽  
Natural Wood ◽  
Dimensional Instability

AbstractFast-growing wood is an abundant and low-cost material and is widely used for structural building and furniture construction. However, inferior mechanical properties and dimensional instability limit its application in advanced engineering structures. Herein, we developed a simple, effective and “green” method to transform bulk poplar into a high-performance wood composite. The wood composite was prepared by the impregnation of the itaconic acid (IA) solution acting as a grafting anchor into the wood matrix, followed by in situ polymerization of styrene upon heating to form a hydrophobic polymer within the wood scaffold. Scanning electron microscope (SEM) analysis revealed that hydrophobic polystyrene (PS) was deposited in wood cell walls and lumens, leading to a reduced water uptake and remarkably enhanced dimensional stability, as well as generally improved mechanical properties. In addition, the PS generated improvement in the thermal stability of the wood composite in comparison with that of natural wood (W).

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