Electron microscopy of rod/coil molecular composites

1983 ◽  
Vol 41 ◽  
pp. 32-33
Author(s):  
S. J. Krause ◽  
W. W. Adams
Keyword(s):  
Critical Factor ◽  
High Strength ◽  
Chain Polymer ◽  
New Class ◽  
Reinforced Composite ◽  
Transmission Electron ◽  
The Matrix ◽  
Molecular Composites ◽  
Flexible Coil ◽  
Rigid Rod

Molecular composites are a new class of structural polymers which are lightweight, high-strength, high-modulus, and environmentally resistant. A rigid-rod, extended chain, polymer is used to reinforce a matrix of flexible, coil-like polymer with the intent of achieving a composite on the molecular level which is analagous to a macroscopic chopped-fiber reinforced composite. The critical factor in making a molecular composite is that the rod-like reinforcing molecules be well dispersed and not phase separate from the matrix polymer to insure that the aspect ratio (ratio of length to width) of the reinforcing phase has a high value. This paper reports the first transmission electron microsopy (TEM) study of phase separation in molecular composites.

Electron microscopy of a triblock copolymer molecular composite

1986 ◽  
Vol 44 ◽  
pp. 790-791
Author(s):  
T. Haddock ◽  
S. J. Krause ◽  
W. W. Adams
Keyword(s):  
Triblock Copolymer ◽  
Critical Factor ◽  
High Strength ◽  
Fiber Spinning ◽  
Chain Polymer ◽  
The Matrix ◽  
Molecular Composites ◽  
Polymer Component ◽  
Flexible Coil ◽  
Rigid Rod

Molecular composites are a new class of structural polymers which are high-strength, high-modulus, thermally stable, and environmentally resistant. A rigid-rod, extended chain polymer component is used to reinforce a matrix of flexible, coil-like polymer component with the intent of achieving a composite on the molecular level. The critical factor in processing a molecular composite is that the rod-like reinforcing component be well dispersed and not phase separate from the matrix component. We previously reported on the morphology of a molecular composite from a physical blend of rigid-rod and flexible-coil homopolymers. In this paper we are reporting on the morphology of a rigid-rod, flexible-coil, triblock copolymer processed by vacuum casting or fiber spinning from a dilute solution.

Electron microscopy of a rigid-rod/nylon thermoplastic molecular composite physical blend

1988 ◽  
Vol 46 ◽  
pp. 748-749
Author(s):  
P. Lloyd ◽  
R. Omlor ◽  
D. Vezie ◽  
S. J. Krause ◽  
S. Kumar ◽  
...  
Keyword(s):  
Critical Factor ◽  
High Strength ◽  
Chain Polymer ◽  
Degradation Temperature ◽  
The Matrix ◽  
Molecular Composites ◽  
Ductile Polymer ◽  
Flexible Coil ◽  
Rigid Rod ◽  
Processing Techniques

“Molecular composites” are a new class of structural polymers which are high-strength, high-modulus, thermally stable, and environmentally resistant. A rigid-rod, extended chain polymer component is used to reinforce a matrix of a ductile polymer with the intent of achieving a composite on the molecular level. The critical factor in processing a “molecular composites” is that the rigid-rod reinforcing component be well dispersed and not phase separate from the matrix component at any stage of processing. For the greatest versatility, a “molecular composites” system should be amenable to fabrication with traditional thermoplastic processing techniques. We previously reported on the morphology of “molecular composites” formed by coagulation spinning from a solution of rigid-rod/stiff-coil polymer blend and from a solution of a rigid-rod/stiff-coil triblock copolymer. Although these polymer systems formed “molecular composites”, they did not have a glass transition temperature below the degradation temperature and could not be consolidated by thermal processing techniques. In this paper we are reporting on the morphology of rigid-rod and flexible-coil thermoplastic blends which are processable by precipitation and thermal consolidation.

Morphology of High-Performance Rigid-Rod Polymer Fibers and Molecular Composites

1989 ◽  
Vol 47 ◽  
pp. 338-339
Author(s):  
W.W. Adams ◽  
S. J. Krause
Keyword(s):  
Tensile Strength ◽  
High Performance ◽  
Liquid Crystalline ◽  
Molecular Level ◽  
Synergistic Effects ◽  
Tensile Modulus ◽  
Commercial Development ◽  
The Matrix ◽  
Molecular Composites ◽  
Rigid Rod

Rigid-rod polymers such as PBO, poly(paraphenylene benzobisoxazole), Figure 1a, are now in commercial development for use as high-performance fibers and for reinforcement at the molecular level in molecular composites. Spinning of liquid crystalline polyphosphoric acid solutions of PBO, followed by washing, drying, and tension heat treatment produces fibers which have the following properties: density of 1.59 g/cm3; tensile strength of 820 kpsi; tensile modulus of 52 Mpsi; compressive strength of 50 kpsi; they are electrically insulating; they do not absorb moisture; and they are insensitive to radiation, including ultraviolet. Since the chain modulus of PBO is estimated to be 730 GPa, the high stiffness also affords the opportunity to reinforce a flexible coil polymer at the molecular level, in analogy to a chopped fiber reinforced composite. The objectives of the molecular composite concept are to eliminate the thermal expansion coefficient mismatch between the fiber and the matrix, as occurs in conventional composites, to eliminate the interface between the fiber and the matrix, and, hopefully, to obtain synergistic effects from the exceptional stiffness of the rigid-rod molecule. These expectations have been confirmed in the case of blending rigid-rod PBZT, poly(paraphenylene benzobisthiazole), Figure 1b, with stiff-chain ABPBI, poly 2,5(6) benzimidazole, Fig. 1c A film with 30% PBZT/70% ABPBI had tensile strength 190 kpsi and tensile modulus of 13 Mpsi when solution spun from a 3% methane sulfonic acid solution into a film. The modulus, as predicted by rule of mixtures, for a film with this composition and with planar isotropic orientation, should be 16 Mpsi. The experimental value is 80% of the theoretical value indicating that the concept of a molecular composite is valid.

Morphology of Rigid-Rod Molecular Composites: An Overview

1988 ◽  
Vol 134 ◽  
Author(s):  
Stephen J. Krause
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Morphological Characterization ◽  
High Ratio ◽  
Structure Property ◽  
Chain Polymer ◽  
Specific Strength ◽  
Composite Systems ◽  
Molecular Composites ◽  
Rigid Rod

ABSTRACTRigid-rod molecular composites are a new class of high performance structural polymers which have high specific strength and modulus and also high thermal and environmental resistance. A rigid-rod, extended chain polymer component is used to reinforce a matrix of a ductile polymer with the intent of achieving a “composite” on the molecular level. After synthesis, the key to producing a molecular composite is to control morphology to disperse the reinforcing rod molecules as finely as possible in the matrix polymer. Individual rod molecules or bundles of molecular rods must have dimensions which result in a high ratio of length to width (aspect ratio) for efficient reinforcement. To achieve this, the reinforcing rod component must not phase separate at any stage of processing. Morphological characterization techniques, which can measure the orientation and dispersion (or, conversely, the degree of phase separation) of rod molecules provide the tools for correlating theoretically predicted and experimentally observed mechanical properties. Various morphological techniques which have been applied to molecular composite systems will be reviewed, including wide angle x-ray scattering and scanning and transmission electron microscopy. Structure-property correlations for molecular composite systems will be discussed with regard to models for mechanical properties. Application of new morphological techniques will also be discussed.

Recent Advances in Morphology and Mechanical Properties of Rigid-Rod Molecular Composites

1989 ◽  
Vol 171 ◽  
Author(s):  
Stephen J. Krause ◽  
Wen-Fang Hwang
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Low Voltage ◽  
Orientation Distribution ◽  
Short Fiber ◽  
Chain Polymer ◽  
Structural Applications ◽  
Molecular Composites ◽  
Rigid Rod ◽  
Aromatic Heterocyclic

ABSTRACTRigid-rod molecular composites are a new class of high performance structural polymers which have high specific strength and modulus and also high thermal and environmental resistance. The concept of using a rigid-rod, extended chain polymer to reinforce a ductile polymer matrix at the molecular level has been demonstrated with morphological and mechanical property studies for aromatic heterocyclic systems, but new materials systems and processing techniques will be required to produce thermoplastic or thermoset molecular composites. Improved characterization and modeling will also be required. In this regard, new results on modeling of mechanical properties of molecular composites are presented and compared with experimental results. The Halpin-Tsai equations from ‘shear-lag’ theory of short fiber composites predict properties reasonably well when using the theoretical modulus of rigid-rod molecules in aromatic heterocyclic systems, but newer matrix systems will require consideration of matrix stiffness, desired rod aspect ratio, and rod orientation distribution. Application of traditional and newer morphological characterization techniques are discussed. The newer techniques include: Raman light scattering, high resolution and low voltage SEM, parallel EELS in TEM, synchrotron radiation in X-ray scattering, and ultrasound for integrity studies. The properties of molecular composites and macroscopic composites are compared and it is found that excellent potential exists for use of molecular composites in structural applications including engineering plastics, composite matrix resins, and as direct substitutes for fiber reinforced composites.

Study on Mechanical Property of Aluminium 6061 with E Glass Fiber Reinforced Composite

2018 ◽  
Vol 877 ◽  
pp. 50-53 ◽  
Author(s):  
Vinayashree ◽  
R. Shobha
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
High Strength ◽  
Matrix Alloy ◽  
Stir Casting ◽  
Reinforced Composite ◽  
Reinforcement Content ◽  
Glass Fiber Reinforced ◽  
The Matrix ◽  
Glass Fibre Reinforced

Aluminium composites are in predominant use due to their lower weight and high strength among the MMC’s. Aluminium 6061 is selected as matrix and E-glass fiber is selected as reinforcement. Fabrication of composite is done by stir casting method. Each fabrication carries the E-glass reinforcement content varied from 2% to 10%. The present article attempts to evaluate the mechanical properties of E-glass fibre reinforced composite and study the effect of reinforcement on the matrix alloy through mechanical properties. When compared to ascast mechanical properties the UTS has increased from 74.28 N/sq mm to 146.8 N/sq mm for a composite at 6% E-glass. The hardness of as-cast has also increased from 22 RHB to 43 RHB at 6% E-glass and the wear of composite has exhibited a decreasing tend with increase in reinforcement content along the sliding distance. The results are analyzed in certain depth in the current paper. The mechanical properties of composites have improved with the increase in the weigh percentage of glass fiber in the aluminium matrix.

scholarly journals Rheological and Mechanical Properties of Silica/Nitrile Butadiene Rubber Vulcanizates with Eco-Friendly Ionic Liquid

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2763
Author(s):  
Munir Hussain ◽  
Sohail Yasin ◽  
Hafeezullah Memon ◽  
Zhiyun Li ◽  
Xinpeng Fan ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Volume Fraction ◽  
High Strength ◽  
Crosslinking Density ◽  
Mechanical And Thermal Properties ◽  
Butadiene Rubber ◽  
Transmission Electron ◽  
The Matrix ◽  
Silica Dispersion ◽  
The Impact

In this paper we designed greener rubber nanocomposites exhibiting high crosslinking density, and excellent mechanical and thermal properties, with a potential application in technical fields including high-strength and heat-resistance products. Herein 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) ionic liquid was combined with silane coupling agent to formulate the nanocomposites. The impact of [EMIM]OAc on silica dispersion in a nitrile rubber (NBR) matrix was investigated by a transmission electron microscope and scanning electron microscopy. The combined use of the ionic liquid and silane in an NBR/silica system facilitates the homogeneous dispersion of the silica volume fraction (φ) from 0.041 to 0.177 and enhances crosslinking density of the matrix up to three-fold in comparison with neat NBR, and also it is beneficial for solving the risks of alcohol emission and ignition during the rubber manufacturing. The introduction of ionic liquid greatly improves the mechanical strength (9.7 MPa) with respect to neat NBR vulcanizate, especially at high temperatures e.g., 100 °C. Furthermore, it impacts on rheological behaviors of the nanocomposites and tends to reduce energy dissipation for the vulcanizates under large amplitude dynamic shear deformation.

scholarly journals Nanocellulose Xerogel as Template for Transparent, Thick, Flame-Retardant Polymer Nanocomposites

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3032
Author(s):  
Wataru Sakuma ◽  
Shuji Fujisawa ◽  
Lars A. Berglund ◽  
Tsuguyuki Saito
Keyword(s):  
Polymer Composites ◽  
Flexural Modulus ◽  
Cellulose Nanofibers ◽  
High Strength ◽  
High Porosity ◽  
Load Bearing ◽  
Surface Areas ◽  
Reinforced Composite ◽  
Reinforcing Fillers ◽  
The Matrix

Cellulose nanofibers (CNFs) have excellent properties, such as high strength, high specific surface areas (SSA), and low coefficients of thermal expansion (CTE), making them a promising candidate for bio-based reinforcing fillers of polymers. A challenge in the field of CNF-reinforced composite research is to produce strong and transparent CNF/polymer composites that are sufficiently thick for use as load-bearing structural materials. In this study, we successfully prepared millimeter-thick, transparent CNF/polymer composites using CNF xerogels, with high porosity (~70%) and high SSA (~350 m2 g−1), as a template for monomer impregnation. A methacrylate was used as the monomer and was cured by UV irradiation after impregnation into the CNF xerogels. The CNF xerogels effectively reinforced the methacrylate polymer matrix, resulting in an improvement in the flexural modulus (up to 546%) and a reduction in the CTE value (up to 78%) while maintaining the optical transparency of the matrix polymer. Interestingly, the composites exhibited flame retardancy at high CNF loading. These unique features highlight the applicability of CNF xerogels as a reinforcing template for producing multifunctional and load-bearing polymer composites.

Study of Nano-Precipitate in High Strength Low Carbon Steel during Tempering by TEM

2013 ◽  
Vol 327 ◽  
pp. 123-127 ◽  
Author(s):  
Long Fei Zuo ◽  
Li Li Qiu ◽  
Bin Hou ◽  
Xiao Hua Chen ◽  
Ming Wen Chen ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Energy Dispersive Spectrometry ◽  
Low Carbon Steel ◽  
High Strength ◽  
Growing Up ◽  
Low Carbon ◽  
Tempering Temperature ◽  
Transmission Electron ◽  
The Matrix ◽  
Oswald Ripening

The behavior of nanoprecipitates of 800Mpa grade high strength low carbon steel during tempering has been studied. Transmission electron microscope (TEM), high resolution transmission electron microscopy (HRTEM) and energy dispersive spectrometry (EDS) were used to systematically analyze the morphology of precipitates and their grain orientation with matrix at different tempering temperatures. Experimental results confirm that the composition of these nanometer sized particles in the matrix was compound carbonitrides containing Ti, V, Mo and other elements. The precipitates of the as-received steel are (Nb,Ti)(C,N) at low tempering temperature, while those at high tempering temperature are composite carbides containing a variety of elements such as Mo, V, Ti and Nb. On the other hand, as tempering temperature increases, precipitates in the steel were slowly growing up and roughening according with the typical Oswald ripening mechanism; a sharp orientation relationship exists between precipitates and matrix.

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