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1.
Based on the difference in melting points between polyamide 66 (PA66) fiber and polyamide 6 (PA6) matrix, all-polyamide composites
were fabricated under various processing conditions. In these all-polyamide composites, the reinforcement and matrix share
the same molecular structure unit (–CONH–(CH2)5–). Because of the chemical similarity of the two components, good bonding at the fiber/matrix interface could be expected.
Effects of processing temperature and cooling rate on the structure and physical properties of composites were investigated
by SEM, DMA, DSC analyses, and static tensile test. Fiber/matrix interface strength benefited from elevated processing temperature.
The static tensile results showed that the maximum of tensile strength was observed in the processing temperature range of
225–245 °C. At different cooling rates, crystallization temperature of PA6 in the composites was increased compared to the
pure PA6 because of the nucleation effect of PA66 fiber surface to the PA6 matrix. A study of the matrix microstructure in
a single fiber-polymer composite gave proof of the transcrystalline growth at the fiber–matrix interface, the reason behind
which was the similar chemical compositions and lattice structures between PA6 and PA66. 相似文献
2.
《Composites Part B》2013,45(1):385-393
The aim of this study was to investigate the erosive wear behavior of glass fiber, CaCO3 particle and glass fiber/CaCO3 hybrid reinforced ABS/PA6 blend based composites. The samples were prepared by using melt mixing and injection molding techniques. The mechanical, thermal, morphological properties and erosive wear behavior were investigated in terms of reinforcing agent type and composition. It was observed that the tensile strength and modulus values of hybrid composites gave a value between tensile strength and modulus values of only fiber reinforced composites and only particle reinforced composites. From DSC analysis it was revealed that Tg and Tm of composites were not significantly affected by reinforcement; however, degree of crystallinity was found to be sensitive to reinforcement type and composition. The impingement angle was found to have a significant effect on the erosive wear behavior. The results indicated that composite materials exhibited maximum erosion rate at impact angle of 30° conforming their ductile erosion behavior. In order to investigate wear mechanisms, eroded surface analysis was done by scanning electron microscopy. Surface analysis showed that repeated impact of hard silica sand particles caused a local removal of the matrix from the fiber surface and led to form craters on the surface of the composite material. 相似文献
3.
The difference in the melting points of polyamide 66 (PA66) fiber and polyamide 6 (PA6) film permits the preparation of all-polyamide
(all-PA) composites by film-packing. Good interface performance and integrated consolidation structure in this all-PA composite
are contributed to the similar chemical composition between PA66 fiber and PA6 matrix. In this paper, the non-isothermal crystallization
kinetics and melting behaviors of PA6 matrix in all-PA composite are studied by differential scanning calorimetry (DSC), in
which the modified Avrami equation, Ozawa model, and Mo equation combining Avrami and Ozawa equation are employed. It is found
that the Mo equation exhibits great advantages in treating the non-isothermal crystallization kinetics for both neat PA6 and
PA6 matrix in all-PA composite. The crystal morphologies of single PA66 fiber–PA6 composite by polarizing microscope (POM)
clearly show a transcrystallinity layer of PA6 around PA66 fiber that proves a remarkable nucleation effect of PA66 fiber
surface on the crystallization of PA6 matrix. 相似文献
4.
C. Wretfors S.-W. Cho R. Kuktaite M. S. Hedenqvist S. Marttila S. Nimmermark E. Johansson 《Journal of Materials Science》2010,45(15):4196-4205
Wheat gluten (WG) is a promising base material for production of “green” plastics, although reinforcement is needed in more
demanding applications. Hemp fiber is a promising reinforcement source but difficulties exist in obtaining desired properties
with a WG-based matrix. This study aimed at improving fiber dispersion and fiber–matrix interactions using a high speed blender
and a diamine as a cross-linker. Samples were manufactured using compression molding, two types of blenders and addition of
diamine. Mechanical properties were assessed with tensile testing. Tensile-fractured surfaces were examined with scanning
electron microscopy (SEM). Protein polymerization and fiber–protein matrix interactions were examined using high performance
liquid chromatography (HPLC) and confocal laser scanning microscopy (CLSM). The results showed that a higher-speed grinding
yielded a more even distribution of fibers and a more polymerized protein structure compared to a lower-speed grinding. However,
these improvements did not result in increased strength, stiffness, and extensibility for the higher-speed grinding. The strength
was increased when the grinding was combined with addition of a diamine (Jeffamine? EDR-176). HPLC, SEM, and CLSM, indicated that diamine added samples showed a more “plastic” appearance together with a stiffer
and stronger structure with less cracking compared to samples without diamine. The use of the diamine also led to an increased
polymerization of the proteins, although no effect on the fiber–protein matrix interactions was observed using microscopical
techniques. Thus, for future successful use of hemp fibers to reinforce gluten materials, an appropriate method to increase
the fiber–protein matrix interaction is needed. 相似文献
5.
Sudhir Tiwari Mohit Sharma Stephane Panier Brigitte Mutel Peter Mitschang Jayashree Bijwe 《Journal of Materials Science》2011,46(4):964-974
The parameters controlling performance of a fiber-reinforced polymer composite are type of matrix and fibers, their amount,
aspect ratio, fiber orientation with respect to loading direction, fiber–matrix interface, and processing technique. In the
case of carbon fiber reinforcement, fiber–matrix interface has always been a serious concern, because of chemical inertness
of carbon fibers toward matrix and hence efforts are continued to enhance the fiber–matrix adhesion. A recent technique of
cold remote nitrogen oxygen plasma was employed for surface treatment of carbon fabric (CF) to enhance its chemical reactivity
and mechanical interaction toward matrix material. Untreated and plasma treated CF were used as bidirectional reinforcement
for developing high performance composites with various specialty polymer matrices such as Polyetherimide, Polyethersulfone,
and Polyetheretherketone. Treated CF reinforced composites showed appreciable improvement in most of the mechanical properties,
which varied with type of plasma, its dozing and matrix used. X-ray Photoelectron Spectroscopy confirmed improvement in O/C
and N/C ratio indicating inclusion of Oxygen and Nitrogen on the surfaces of fibers due to plasma treatment, which was responsible
for enhanced adhesion. Similarly, Fourier Transform Infrared–Attenuated Total Reflectance Spectroscopy indicated presence
of ether, carboxylic, and carbonyl functional groups on the plasma-treated surface of fibers. Raman spectroscopy indicated
slight distortion in graphitic structure of treated CF. Scanning Electron Microscopy also indicated changes in the topography
of treated CF, indicating enhanced mechanical interlocking with matrix. 相似文献
6.
Effect of moisture absorption on the micromechanical behavior of carbon fiber/epoxy matrix composites 总被引:1,自引:0,他引:1
J. I. Cauich-Cupul E. Pérez-Pacheco A. Valadez-González P. J. Herrera-Franco 《Journal of Materials Science》2011,46(20):6664-6672
Carbon fiber/epoxy material in the form of a single fiber unidirectional composite was subjected to controlled humidity environments.
Moisture uptake in polymer composites has significant effects on the mechanical properties of the matrix as well as on the
final performance of the composite material. Diminishing of the mechanical properties of the matrix is attributed to a decrease
of its glass transition temperature (T
g). The quality of the fiber–matrix interphase was assessed using the single fiber fragmentation test and the fiber-fragment
length, considered as an indicator of interfacial quality. In order to measure the fiber fragment lengths and indentify failure
mechanism at the interface optical observation and acoustic emission technique were used. The speed of propagation of an acoustic
wave in the material was also determined. A comparison is made of interfacial shear strength values determined by acoustic
emission and optical techniques. Excellent agreement between the two techniques was obtained. By means of a micromechanical
model, it was possible to determine from the fragmentation lengths a measure of the interfacial shear strength between the
fiber and the matrix. The role of moisture uptake swelling of the matrix on the residual stresses is considered to be important
when considering the effect deterioration of interfacial shear properties. Both the contribution of the radial stresses and
the mechanical component of fiber–matrix adhesion are seen to decrease rapidly for higher moisture contents in the matrix
and/or interface. 相似文献
7.
Solid particle erosion in industrial applications has been a serious problem in many engineering fields. Earlier studies on fiber-reinforced plastic (FRP) composites were mainly focusing on the erosive wear behavior at several different impact angles. However, the effect of fiber orientation on FRP composites has not been thoroughly investigated. Since fiber orientation is one of the important factors in which causing erosive wear damages to FRP composites, in order to understand the virtue of this problem, it is important to investigate the effect of fiber orientation at different impact angles. In this research, the effect of fiber orientation of unidirectional fiber-reinforced plastic composites on erosive wear behavior was studied. Sandblasting-type erosion tests were conducted on the FRP composites with fiber orientation ranging at three impact angles to clarify the relation between fiber orientation and erosive wear behavior. The Dyneema fiber (ductile material) and the carbon fiber (brittle material) were used for the reinforcement fiber in FRP. From the result, it is confirmed that CFRP composites with higher fiber orientation angle erode faster than the composites with lower fiber orientation angle. But the erosion characteristic of DFRP was almost the same regardless of the fiber orientation angle. The damaged surfaces of the FRP composites were then analyzed using scanning electron microscopy and the possible erosion wear mechanisms were investigated. 相似文献
8.
This study focuses on a novel technique to produce thermoplastic composites directly from bicomponent nonwovens without using
any resins or binders. Conceptually, the structure of the bicomponent fibers making up these nonwovens already mimics the
fiber–matrix structure of fiber reinforced composites. Using this approach, we successfully produced isotropic thermoplastic
composites with polymer combinations of polyethylene terephthalate/polyethylene (PET/PE), polyamide-6/polyethylene (PA6/PE),
polyamide-6/polypropylene (PA6/PP), and PP/PE. The effects of processing temperature, fiber volume fraction, and thickness
of the preform on the formation and structure of the nonwoven composites were discussed. Processing temperatures of 130 and
165 °C for PE and PP matrices, respectively, resulted in intact composite structures with fewer defects, for fiber volume
fraction values of up to 51%. Moreover, an insight into the changes on the fine structure of the bicomponent fibers after
processing was provided to better explain the mechanics behind the process. It is hypothesized that the composite fabrication
process can result in annealing and increases the degree of crystallinity and melting temperature of polymers by thickening
lamellae and/or removing imperfections. One of the other outcomes of this study is to establish what combination of mechanical
properties (tensile and impact) nonwoven composites can offer. Our results showed that compared to glass mat reinforced thermoplastic
composites, these novel isotropic nonwoven composites offer high specific strength (97 MPa/g cm−3 for PA6/PE), very high strain to failure (152% for PP/PE), and superior impact strength (147 kJ/m2 for PA6/PP) which can be desirable in many critical applications. 相似文献
9.
Du-qing Cheng Xue-tao Wang Jian Zhu Dong-hua Qiu Xiu-wei Cheng Qing-feng Guan 《Frontiers of Materials Science in China》2009,3(1):56-60
A new composite brake material was fabricated with metallic powders, barium sulphate and modified phenolic resin as the matrix
and carbon fiber as the reinforced material. The friction, wear and fade characteristics of this composite were determined
using a D-MS friction material testing machine. The surface structure of carbon fiber reinforced friction materials was analyzed
by scanning electronic microscopy (SEM). Glass fiberreinforced and asbestos fiber-reinforced composites with the same matrix
were also fabricated for comparison. The carbon fiber-reinforced friction materials (CFRFM) shows lower wear rate than those
of glass fiber- and asbestos fiber-reinforced composites in the temperature range of 100°C-300°C. It is interesting that the
frictional coefficient of the carbon fiber-reinforced friction materials increases as frictional temperature increases from
100°C to 300°C, while the frictional coefficients of the other two composites decrease during the increasing temperatures.
Based on the SEM observation, the wear mechanism of CFRFM at low temperatures included fiber thinning and pull-out. At high
temperature, the phenolic matrix was degraded and more pull-out enhanced fiber was demonstrated. The properties of carbon
fiber may be the main reason that the CFRFM possess excellent tribological performances. 相似文献
10.
M. A. Mazo C. Palencia A. Nistal F. Rubio J. Rubio J. L. Oteo 《Journal of Materials Science》2012,47(13):5169-5180
Carbon nanofibers/glass (CNF/G) nanocomposites were obtained from a glass powder of low melting point and pristine CNFs. Green
bodies containing from 0 to 22 % (v/v) of CNFs were sintered under nitrogen atmosphere in the 550–700 °C temperature range
with different holding times. A fully microstructure characterization, by means of Hg porosimetry and N2 adsorption, was carried out for understanding the CNFs/G composites behavior during the sintering process. This understanding
is required to optimize the microstructural design of CNFs/glass nanocomposite materials. During sintering two different and
simultaneous phenomena occur the matrix crystallization and the pore formation. The glass matrix crystallization temperature
decreases from 650 to 550 °C, when CNFs concentration increases to 22 % (v/v). The glass matrix produces the CNFs degradation
and generates gaseous species which lead to homogeneous or foamy materials. This depends on the CNFs concentration and thermal
treatment conditions. Foamy nanocomposites present pore size distributions with pores <0.1 and close to 20 μm. The glass matrix
wets the CNFs and produce their degradation been of 1 % of carbon loss in all nanocomposites. 相似文献
11.
In this study, a micromechanical model is presented to study the combined normal, shear and thermal loading of unidirectional
(UD) fiber reinforced composites. An appropriate truly meshless method based on the integral form of equilibrium equations
is also developed. This meshless method formulated for the generalized plane strain assumption and employed for solution of
the governing partial differential equations of the problem. The solution domain includes a representative volume element
(RVE) consists of a fiber surrounded by corresponding matrix in a square array arrangement. A direct interpolation method
is employed to enforce the appropriate periodic boundary conditions for the combined thermal, transverse shear and normal
loading. The fully bonded fiber–matrix interface condition is considered and the displacement continuity and traction reciprocity
are imposed to the fiber–matrix interface. Predictions show excellent agreement with the available experimental, analytical
and finite element studies. Comparison of the CPU time between presented method and the conventional meshless local Petrov–Galerkin
(MLPG) shows significant reduction of the computational time. The results of this study also revealed that the presented model
could provide highly accurate predictions with relatively small number of nodes and less computational time without the complexity
of mesh generation. 相似文献
12.
ABSTRACTThe effect of temperature on the mechanical behavior of carbon fiber reinforced polyphenylenesulfide (PPS) composites was investigated by compressive and flexural tests from ambient temperature up to 150°C. The failure morphologies of the C/PPS composites were analyzed to identify the variation of failure modes. Related results showed that the mechanical behavior of C/PPS composites decreased severely with the increase of temperature due to the softening of matrix. The PPS resin film tensile test was carried out and the PPS matrix behavior was recognized as the main factor to dominate the mechanical behavior of composites under compressive/flexural loading at elevated temperatures. It can be found that there was an approximate linear relationship between the compression properties of C/PPS composites and the PPS matrix. The dependence of failure modes of composites on temperatures was closely related to the mechanical behavior of PPS matrix. 相似文献
13.
An experimental study of the incorporation of non-fluorinated and fluorinated Twaron fibers in polypropylene (PP) is presented. Surface modifications were made to Twaron fiber by direct fluorination technique using elemental fluorine in order to improve the interfacial adhesion between the fiber and matrix. Composites of PP/Twaron fiber (both Fluorinated and non-fluorinated) with 0.6%, 1.25%, 5% and 10% of Twaron fibers (w/w) were prepared by a solution method. Mechanical behaviour was estimated by the measurement of the tensile strength. The mechanical properties of PP improve significantly with the incorporation of Twaron fibers and fluorinated fiber composites show superior mechanical properties compared to the non-fluorinated system. The morphology was determined by scanning electron microscopy (SEM), showing good dispersion of the fibers. The thermal and crystallization behaviour of PP/Twaron fiber composites were studied by thermogravimetry (TG) and differential scanning calorimetry (DSC). The effect of fiber content and fiber surface treatments on the thermal properties was evaluated. DSC analysis exhibited an increase in the crystallization temperature and crystallinity, melting temperature upon the addition of fluorinated fibers to the PP matrix. This is attributed to the nucleating effects of the fiber surfaces. Also the thermal stability (from TG) and surface energy (determined from contact angle measurement) increased for fluorinated fiber composites. Surface modification of Twaron fibers leads to improved adhesion with the PP matrix and hence an improvement in properties of the Twaron fiber-PP composites. 相似文献
14.
Mengjie Wang Xiaolin Liu Xiangrong Wang Yong Zhang 《Journal of Materials Science》2012,47(6):2535-2540
A glass with a composition of 22.5SrO–22.5BaO–15Nb2O5–40SiO2 (mol %) was prepared by a melt-quenching method and then heat-treated at 950 °C for different crystallization time. Microstructure
observations were carried out using scanning electron microscope and dielectric properties were measured by a LCR meter. The
experimental results show that volume fraction of the crystalline phase increased, dielectric constant maximum enhanced, and
Curie temperature shifted as the crystallization time is prolonged. The decrease in the Curie temperature for the sample crystallized
at 950 °C for 1 h is considered to be caused by the clamping effect from the glass matrix or small compositional fluctuation.
Impedance spectroscopy has been employed to study the polarization contributions arising from the glass and crystalline phases
in the glass–ceramics for different crystallization time. With the increase in crystallization time, the magnitudes of impedance
and modulus as well as the relaxation frequency changed significantly. The activation energy calculated from the relaxation
frequency increased for the glass phase due to a denser network structure, while the crystalline phase showed a slight decrease
implying there is no change in its polarization mechanism. 相似文献
15.
This paper is concerned with the derivation of a micromechanics model of a new type of piezoelectric fiber reinforced composite
(PFRC) materials. A continuum mechanics approach is employed to determine the effective properties of these composites. The
piezoelectric fibers of these composites are considered to be electroded at the fiber–matrix interface such that the electric
fields in the fiber and matrix become equal in the direction transverse to the fiber direction. The model has been verified
with the existing models. The present model also predicts that the effective piezoelectric coefficient of these PFRC which
accounts for the actuating capability in the fiber direction due to the applied field in the direction transverse to the fiber
direction improves over the corresponding coefficient of the material of the piezoelectric fibers if the fiber volume fraction
exceeds a critical fiber volume fraction. 相似文献
16.
E. Pérez-Pacheco M. V. Moreno-Chulim A. Valadez-González C. R. Rios-Soberanis P. J. Herrera-Franco 《Journal of Materials Science》2011,46(11):4026-4033
The effect of the interfacial microstructure on the stress transfer for a single-fiber carbon fiber/epoxy matrix composite
with two different levels of fiber–matrix adhesion for a temperature range between 25 and 115 °C was studied. The heterogeneity
of the matrix in the neighborhood of the fiber on the effective mechanical properties of the composite and the possible interactions
fiber–matrix that could lead to the development of an interphase dissimilar to the bulk matrix were also analyzed. The preferential
absorption of one component of the matrix on the carbon fiber surface is considered to play a key factor on the interfacial
behavior for a varying temperature. The matrix-interphase amine-resin stoichiometry is considered to be the main parameter
controlling the single-fiber composite behavior when exposed to high temperature. 相似文献
17.
Rare earth compound Ytterbium fluoride (YbF3) in nano-size (40–80 nm) was employed for surface treatment of carbon fabric (CF) to improve its wettability with polyetherimide
matrix. Composites were developed based on untreated and surface-treated CF with three doses, 0.1, 0.3, and 0.5 wt%, of YbF3 in ethyl alcohol suspension. The composites were analyzed for interlaminar shear strength (ILSS). Improvement in ILSS was
observed for treated fabric reinforced composites and it was maximum (61%) for 0.3 wt% dose of YbF3. The adhesive wear performance of composites was evaluated by sliding a pin of composite against mild steel disc under varying
loads (200–600 N). The treated fabric composites exhibited lower coefficient of friction (μ) and higher wear resistance (W
R). ILSS and W
R showed good linear correlation. Both properties were highest for 0.3% YbF3 dosing. Increased roughness of fiber surface and adhesion of nano-particles on the fiber surface was observed in scanning
electron microscopic (SEM) studies. SEM studies of worn surfaces of composites were performed to understand wear mechanisms.
Atomic force microscopic studies indicated substantial increase in roughness value of CF. 相似文献
18.
Poly(ethylene terephthalate) (PET)/silica composites were prepared by melt compounding, and their rheological properties and
isothermal crystallization were discussed. Introduction of silica particles (0.5–2 wt.%) increased the storage modulus (G′) and decreased loss tangent (tanδ). However, the effect of the particles on rheological properties became negligible at
a high frequency more than ca. 70 rad/s. In the Cole–Cole plot, the PET/silica composites showed little deviation from the
master curve regardless of the presence of silica particles. The particles increased the relaxation time of PET at particularly
low frequency. The isothermal crystallization kinetics of PET/silica was examined using a differential scanning calorimeter
(DSC). The half-time of crystallization was decreased with increasing the silica content. The incorporation of silica particles
decreased the equilibrium melting temperature by ca. 5.5 °C. In addition, the composites exhibited higher average value of
Avrami exponent (2.7–2.9) in comparison with that of pure PET (2.2). 相似文献
19.
Sanjay K. Nayak Smita Mohanty Sushanta K. Samal 《Materials Science and Engineering: A》2009,523(1-2):32-38
The present article summarizes the development of polypropylene-bamboo/glass fiber reinforced hybrid composites (BGRP) using an intermeshing counter rotating twin screw extruder followed by injection molding. Maleic anhydride grafted polypropylene (MAPP) has been used as a coupling agent to improve the interfacial interaction between the fibers and matrix. The crystallization and melting behavior were investigated employing differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) indicates an increase in thermal stability of the matrix polymer with incorporation of bamboo and glass fibers, confirming the effect of hybridization and efficient fiber matrix interfacial adhesion. The dynamic mechanical analysis (DMA) showed an increase in storage modulus (E′) indicating higher stiffness in case of hybrid composites as compared with untreated composites and virgin matrix. The rheological behavior of the hybrid composites has also been studied using time–temperature superposition (TTS) principle and corresponding viscoelastic master curves have been constructed. 相似文献
20.
The properties of the interfacial transition zone (ITZ) of steel fiber and the bulk matrix were quantified using the backscattered
electron imaging analysis (BSE-IA) and the scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), and
their relationship with the mechanical properties of steel fiber-reinforced mortars was studied. The water and binder ratio
(w/b) of mortar, the amount of silica fume and steel fiber were varied. From the quantitative analysis, a higher build-up of calcium
hydroxide was found from the steel fiber’s interface up to 2 or 4 μm distance away and its build-up was reduced with the 10%
cement replacement by silica fume. Porosity in the ITZ and bulk matrix decreased the fracture energy, compressive energy and
debonding load of steel fiber-reinforced mortar. However, its effect became marginal if a substantial amount of C–S–H or steel
fibers appeared in the ITZ and bulk matrix, which increased the studied mechanical properties. 相似文献