pinecone/core-2020-05-10-deduplication huggingface dataset:
Structure-property relationships in glass reinforced polyamide, part 2: The effects of average fiber diameter and diameter distribution

We present the results of an extensive study of the influence of average fibre diameter and the width of the diameter distribution on the performance of injection moulded glass-fibre reinforced polyamide 66. In the average fibre diameter range from 9-18m dry-as-moulded (DaM) composite unnotched impact and tensile strength decreased significantly. The composite notched impact performance and tensile modulus showed little dependence on fibre diameter. The influence of broadening the fibre diameter distribution by blending glass fibre samples of different average diameter was found to be particularly negative on the level of composite unnotched impact when compared at equal number average diameter. After hydrolysis treatment the composite tensile strength and modulus exhibited a large drop compared to the DaM results. In contrast, the unnotched impact results became insensitive to fibre diameter after hydrolysis. The average level of unnotched impact after hydrolysis was sufficiently high to show an increase over DaM when the fibre diameter was above 14m. Residual fibre length correlated significantly with fibre diameter with a lower average length for thinner fibres. The interfacial shear strength was found to be in the range of 26-34 MPa for DaM composites. There was a highly significant inverse correlation between the DaM interfacial strength and the average fibre diameter. It is shown that results from both tensile and unnotched impact measurements can be brought back to single trend lines by using a Z average value for the average fibre diameter which is more heavily weighted to the thicker fibres in the distribution
Structure-property relationships in glass-reinforced polyamide, Part 3: Effects of hydrolysis ageing on the dimensional stability and performance of short glass-fiber-reinforced polyamide 66

We present results on an in-depth study of the effects of hydrolysis testing on the mechanical performance, weight change, and dimensional stability of injection moulded glass-fibre reinforced polyamide 66 based on two chopped fibre products with different sizing formulations. Composite and resin samples have been characterised both dry as moulded and after conditioning at either 120°C or 150°C for a range of times up to 1000 hours. The results reveal that hydrothermal ageing in water-glycol mixtures results in significant changes in the mechanical performance, weight, and dimensions of these materials. The negative effects of conditioning could be mitigated to some degree by the appropriate choice of the glass fibre sizing; however the sizing effect diminished with increasing conditioning time. All materials showed a weight increase due to conditioning at 120°C which was typical of a single Fickian diffusion process and there was clear evidence of multiple processes involved when conditioning at 150°C. It was not apparent that the glass fibre sizing affected the dimensional stability of the composites. We show that there is a strong correlation between the swelling of these samples and the level of fluid adsorption. Although the PA66 resin showed reasonably homogeneous swelling, the composites exhibited different levels of swelling depending on direction. These effects were well in line with the known effects of fibres on restriction of the matrix deformation (mechanical, thermal or moisture swelling) in the fibre direction. These differences correlate well with the average fibre orientation with respect to the various direction axes. Composite tensile strength and unnotched impact resistance appeared to scale inversely with the level of swelling of the material
The shock and release behavior of an aerospace-grade cured aromatic amine epoxy
resin

Knowing the dynamic behavior of polymer materials that are used in the
construction of fiber-reinforced composite materials is particularly important
for such materials that are subjected to impact. In this work, we have conducted
a number of plate-impact experiments on a commercially important aromatic amine
epoxy resin that is used in the construction of carbon fiber composite
materials. The measured Hugoniot in shock velocity–particle velocity space was
Us = 2.65 + 1.55 up ( ρ0 = 1.141 g/cc), and is similar to the measured Hugoniots
of other resins presented by different researchers. We have also measured the
longitudinal stress in the shocked material and shown, in common with other
polymers, that above a threshold stress, an increase in shear strength with
impact stress is obser
Viscoelastic behavior of a polyester resin concrete reinforced with nonmetallic bars under bending loads

This paper deals with the study of a highly durable polyester polymer concrete reinforced with glass fibre reinforced polymer rebars. The paper describes the properties of this specific concrete, which were tested using different experimental techniques such as porosimetry, scanning electron microscopy and petrography. Likewise, characterisation in a macro-scale was carried out to define the mechanical properties of the material (modulus of elasticity, stress-strain curve, ultimate strength and bond). Based on the latter properties, the paper presents a relatively simple method to estimate the ultimate bearing capacity of beams under bending load. The calculation method has been verified by testing beams and full-scale elements. At the end, and due to the viscoelastic nature of the polymer, several considerations will be made in order identify safety factors dependent on the loads nature: permanent loads (deferred deformations) and live loads.Peer ReviewedPostprint (author’s final draft
Adaptation of Polystyrene/Multi-Wall Carbon Nanotube Composite Properties In Respect of its Thermal Stability

Polystyrene (PS)/multi-wall carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing and by coagulation of PS/MWCNT sonicated dispersion. Before mixing and coagulation particles of MWCNT were covered with PS nanospheres by microemulsion polymerization to increase their dispersibility and compatibility with the matrix. Microemulsion polymerization was carried out under sonication in the presence of surfactants and a cross-linking agent. The structure of modified MWCNT filler was revealed by SEM and TEM microscopy analyses. They show that PS is well grafted onto surface of MWCNT in form of ca 30 nm nanospheres or as ca 3-8 nm PS film layer. Significant changes in properties were recorded mainly for the coagulated sample. Although no shift of T-g was recorded for the melt mixed composite, the coagulated sample shows an increase by 9 degrees C. Also the reinforcing effect of MWCNT was more pronounced for the same method of preparation (further supported by the filler modification). The creep response of this material shifts to longer times not only in the T-g area, but also as low as 70 degrees C below it, which is perceived as an improvement of temperature stability (the same properties kept for a longer time). This was also proved by the increase of creep modulus, and consequently by the prolonged time needed to reach the same tensile creep compliance after aging
Synthesis and Mechanical Properties of Polybenzimidazole Nanocomposites Reinforced by Vapor Grown Carbon Nanofibers

This is a preprint of an article published in Polymer Composites. 31(3):491-496 (2010) JOHN WILEY & SONS INC URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-0569Polybenzimidazole (PBI) nanocomposites containing 0.5-5 wt% vapor grown carbon nanofibers (VGNFs) were successfully synthesized by solvent evaporation method. Fracture morphology examination confirmed the uniform dispersion of VGNFs in the matrix. The mechanical properties of neat PBI and the nanocomposites were systematically measured by tensile test, dynamic mechanical analysis (DMA), hardness measurement, and friction test. Tensile tests revealed that Young\u27s modulus increased by about 43.7% at 2 wt% VGNFs loading, and further modulus growth was observed at higher filler loadings. DMA studies showed that the nanocomposites have higher storage modulus than neat PBI in the temperature range of 30-350 degrees C, holding storage modulus larger than 1.54 GPa below 300 degrees C. Outstanding improvement of hardness was achieved for PBI upon incorporating 2 wt% of VGNFs. The results of friction test showed that coefficient of friction of PBI nanocomposites decreased with VGNFs content compared with neat PBI
Tensile Properties and Reinforcement Mechanisms of Natural Rubber/Vapor-Grown Carbon Nanofiber Composite

This is a preprint of an article published in Polymer Composites. 31(6):1099-1104 (2010) JOHN WILEY & SONS INC URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-0569Natural rubber (NR) composites with different contents of 1, 3, 10, and 20 wt% vapor-grown carbon nanofibers (VGCFs) were synthesized using a solvent casting method. The initial modulus of composites was improved by 26.5 %/wt% as the VGCFs were added, and the NR/3 wt%VGCF composite had the largest tensile strength. The experiment values of initial moduli agreed well with the values predicted by the Halpin-Tsai theory. The reinforcement mechanisms of the composites were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and wide-angle X-ray diffraction (WAXD). It was found that an efficient stress transfer occurred from NR to VGCFs under the uniaxial stretching. The addition of 10 wt% VGCFs could promote the nucleation process of NR, which resulted in the characteristic of the strain-induced crystallization (SIC) in NR/10 wt%VGCF composite even for low strain
Fabrication, Characterization and low-velocity impact testing of hybrid sandwich composites with polyurethane/layered silicate foam cores

A series of nanophased hybrid sandwich composites based on polyurethane/montmorillonite (PU/MMT) has been fabricated and characterised. Polyaddition reaction of the polyol premix with 4,4'-diphenylmethane diisocyanate was applied to obtain nanophased polyurethane foams which were then used for fabrication of sandwich panels. It has been found that the incorporation of MMT resulted in higher number of PU cells with smaller dimensions and higher anisotropy index (cross-sections RI and RII). The obtained materials exhibited improved parameters in terms of thermal insulation properties. The results also show that nanophased sandwich structures are capable of upholding withstanding higher peak loads than those made of neat polyurethane foam cores when subject to low-velocity impact despite lower density than that of neat PU foams. This is especially significant for multi-impact recurrences within the threshold loads and energies studied
Matrix Hybridization in the Interlayer for Carbon Fiber Reinforced Composites

Polymeric composites have gone through a level of maturity beyond the laboratory stage with the development of the Boeing 787, the structure of which contains more than 50% composites. Nonetheless, a basic understanding of the material used in its primary structure has not been extensively investigated. For instance, micromechanical models are inadequate as they always assume an evenly distributed homogeneous matrix, without following classic lamination theory, which assumes constant stress through the laminate thickness. Our program now in its third year at the Polymeric Composites Laboratory in Seattle, supported by industry as well as government agencies, and in collaboration with several universities on a global scale, is developing such concepts for understanding and improving matrices in layered configurations. This effort focuses on the development of interlayer systems used as enablers to improve certain properties of the composite, such as fracture-toughness and crack-propagation inhibition. POLYM. COMPOS., 31:1965–1976, 2010.United States. Air Force Office of Scientific ResearchGloCal Network Corporatio
Behavior of sandwich structures and spaced plates subjected to high-velocity impacts

This work evaluates the behavior of sandwich and spaced plates subjected to high-velocity impacts. The sandwich structures were made of glass/polyester face-sheet and a PVC foam core. The spaced plates were made of two plates of the same material of the sandwich face-sheet at a distance equal to the core thickness. The residual velocity, the ballistic limit, and the damage area were selected to compare the response of both structures. The residual velocity and ballistic limit was very similar in both cases. Nevertheless, the damage area of sandwich structures and spaced plates differed due to the dissimilar properties between the sandwich core and the air inside of the spaced plates. An analytical model, based on energy criteria, was applied to estimate the residual velocity of the projectile, the absorbed energy by each facesheet, and the ballistic limit in the spaced platesSpanish Comision Interministerial de Ciencia y Tecnologia; contract grant number: TRA2007-66555.Publicad
Mechanical properties of polyamide 6 reinforced microfibrilar composites

The mechanical behavior of microfibrilar composites (MFC), consisting of a matrix of high-density polyethylene (HDPE) and reinforcement of polyamide 6 (PA6) fibrils, with and without compatibilization, was studied. The composites were produced by conventional processing techniques with various shape and arrangement of the PA6 reinforcing entities: long, unidirectional, or crossed bundles of fibrils (UDP and CPC, respectively), middle-length, randomly oriented bristles (MRB), or non-oriented micrometric PA6 spheres (NOM). The tensile, flexural, and impact properties of the MFC materials (UDP, CPC, and MRB) were determined as a function of the PA6 reinforcement shape, alignment and content, and compared with those of NOM, the non-fibrous composite It was concluded that the in-situ MFC materials based on HDPE/PA6 blends display improvements in the mechanical behavior when compared with the neat HDPE matrix, e.g., up to 33% for the Young modulus, up to 119% for the ultimate tensile strength, and up to 80% for the flexural stiffness.Contract grant sponsor: Fundação para a Ciência e Tecnologia (FCT); contract grant number: SFRH/BPD/45252/2008 (to NVD).Contract grant sponsor: Fundação para a Ciência e Tecnologia (FCT); contract grant number: POCI/CTM/57358/2004
Fatigue Behavior of Polyamide 66/Glass Fiber Under Various Kinds of Applied Load

In this study, the fatigue behavior of polyamide 66 reinforced with short glass fibers and especially the role of glass fibers has been investigated under two kinds of cyclic loading. tension–tension fatigue tests with stress controlled and alternative flexural fatigue test with strain controlled were carried out. The main topics include microscope damage observation, described by fiber/matrix debonding and interfacial failure, endurance limit with Wohler curves, effect of self-heating temperature. For both tests, the surface temperature increases with an increasing applied load. The results show that the self-heating has an important effect in the failure point where the Wohler curves join each other. The fracture surface was analyzed by scanning electron microscope for both applied loads. The stress ratio is −1 for alternative flexural fatigue test and 0.1 and 0.3 for tension–tension fatigue test ones at frequencies ranging 2–60 Hz
Developing ethylene-propylene-diene rubber compounds for industrial applications using a sulfur-bearing silanized silica nanofiller

This is the peer reviewed version of the following article: Polymer Composites, which has been published in final form at http://dx.doi.org/10.1002/pc.22609. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The loading of a sulfur-bearing silanized silica nanofiller in ethylene-propylene-diene rubber with 4.5 wt % of ethylidene norbornene diene content was increased progressively to 60 parts per hundred rubber by weight. The rubber compounds were cured via the tetrasulfane groups of the silane by adding sulfenamide accelerator and zinc oxide. The hardness, tensile strength, elongation at break, stored energy density at break, tear strength, Young’s modulus, M50-M300, compression set, cyclic fatigue life and bound rubber content of the rubber \ud
vulcanizates were measured.  With the exception of the elongation at break and compression set which deteriorated, the remaining properties improved and the rate of cure, optimum cure time and crosslink density benefitted also when the loading of silica was increased in the rubber. The bound rubber content was unchanged and the cyclic fatigue life of the rubber vulcanizate enhanced considerably when silica was added. Optimizing the chemical bonding between the rubber and filler via the tetrasulfane groups of TESPT reduced the chemical curatives in the rubber. This was a major improvement in health, safety and environment
Cost-effective manufacturing process for the development of automotive from energy efficient composite materials and sandwich structures

The advanced composite materials are increasingly being used in the automotives for their ultralight physical properties and super strong mechanical properties. This research examines the cost-effective single-step liquid resin infusion manufacturing process for developing all composite car body as the generally used sheet molding compound manufacturing process is highly capital intensive. Three different scaled down models of the Eco car were developed focusing on minimal weight and air drag coupled with aesthetics. Structural design and analysis was carried out using the Pro/E and Ansys tools. The Pro-E model was scaled up to generate computer-aided drafting drawings for tool development. Different stations were marked on the model and sliced virtually for development of pattern. Moreover, the mold was manufactured from carbon and glass/polyester composites for prototype manufacturing of the car body. This involved manual placement of desired number of carbon layers as preform on female side of the mold. The vacuum sucked the resin through a number of carefully selected entry ports which ensured effective resin distribution and impregnation. Polycarbonate wind shield was thermoformed in the convection oven according to streamlined geometry of car body and hinged. The car body was integrated with the compatible floor panels and accessories. The crumble zone shock absorber in the bumper was manufactured using successive layers of nomax honeycomb and polyvinyl chloride rigid foam to dampen the accidental shock. The car performed remarkably well in the Eco marathon race held at Malaysia, 35:97–104, 2014. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineer
Synthesis and microstructural characterization of kaolin-polyethylene composites

In this article, the preparation and characterization of
kaolin/polyethylene composites are presented. Microstructural
characteristics of six different kaolin–polyethylene
composites with varying percentage
compositions of kaolin and polymer were produced
using a modified melt compounding approach, was
explored. The characterization methods employed are
scanning electron microscopy (SEM), attenuated total
reflectance mid Infrared (ATR-MIR), X-ray powder diffraction
(XRD), thermogravimetric and differential thermal
analysis (TGA-DTA), compressive, flexural
strengths and impact resistance analysis. The implications
of the results are discussed for the design of
kaolin/polymer composites for constructional purposes.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-0569hb201
EFFECT OF DESICCANT CHARACTERISTICS ON THE PROPERTIES OF PS/ZEOLITE FUNCTIONAL PACKAGING MATERIALS

Desiccant composites were prepared from a polystyrene homopolymer (PS) and a high impact copolymer (HIPS). Five zeolites were used as adsorbents which included the A and X types frequently used in industrial practice. Composites containing zeolites up to 50 vol% were homogenized in an internal mixer and then compression molded to 1 mm thick plates. The results proved that the water adsorption capacity of zeolites depends on the total volume of the pores, while the rate of adsorption on thermodynamics, on the equilibrium con-stant of adsorption. On the other hand, zeolite characteristics influence the moisture ad-sorption of the composites only marginally; adsorption capacity is determined by zeolite content, while the rate of adsorption by the properties of the polymer. Composites prepared with X type zeolites have somewhat smaller water adsorption capacity than those containing their A type counterparts. The dispersion of the zeolite is very good both in PS and in HIPS composites. Mechanical properties are excellent mainly because of the good interfacial adhesion between the components. Because of their larger surface energy, composites containing X type zeolites have larger viscosity and they reinforce the polymer more than A type desiccants. Matrix properties influence mainly application related properties, reinforcement and ductility is better in HIPS than in PS composites
Properties of Cu nanoparticles-poly(N-methylpyrrole) composites

© 2014 Society of Plastics Engineers. Spherical copper nanoparticles (Cu-NPs) have been immobilized on the compact surface of potentiostatically generated poly(N-methylpyrrole) (PNMPy) films by applying a reduction potential of -0.60 V to a deionized water solution of CuCl2. Although the number density of Cu-NPs obtained using this procedure is not high (4·106 cm-2), the average diameter is relatively high (?50 nm). The surface topology and roughness of films with Cu-NPs-PNMPy are intermediate between those obtained for as prepared PNMPy and reduced PNMPy. Analysis of the electrochemical properties indicates that Cu-NPs promote the electroactivity of the PNMPy, this effect being more evident for composited made with the thinnest PNMPy films. In opposition, the electrostability and electrical conductivity are not enhanced by deposited Cu-NPs. Similar findings are obtained for bilayered PNMPy-Cu-NPs-PNMPy films. POLYM. COMPOS., 37:594-601, 2016.Peer ReviewedPreprin
Toughened carbon fiber fabric-reinforced pCBT composites

Toughened carbon fiber-fabric reinforced polymerized\ud
cyclic butylene terephthalate (pCBT) composites were\ud
obtained by chemical modification of cyclic butylene\ud
terephthalate (CBT) with small amounts of epoxy resin\ud
and isocyanates as chain extenders. Homogeneous\ud
CBT/epoxy and CBT/isocyanate blends were prepared\ud
by melt blending the components in a lab-scale batch\ud
mixer at low temperatures and high shear rate. Melt\ud
blending was stopped before the ring-opening polymerization\ud
of CBT could start. The modified CBT was\ud
the starting material for carbon fiber fabric-reinforced\ud
pCBT composites (fiber content at about 65 wt%)\ud
which were prepared by ring-opening polymerization\ud
during compression molding using a simple powder\ud
prepreg method. Interlaminar shear strength, flexural\ud
strength, and failure strain of the chemically modified\ud
composites increased up to 60% with respect to\ud
unmodified pCBT composites. Nevertheless, the flexural\ud
moduli slightly decreased due to the toughening\ud
effect of the chain extender on the pCBT matrix. Drop\ud
weight impact tests revealed that the energy absorption\ud
of the modified composites was relatively higher\ud
as compared to unmodified pCBT composites.Peer ReviewedPostprint (author’s final draft