Abstract: It is a major challenge to build a bridge superstructure
that has long-term durability and low maintenance requirements. A
solution to this challenge may be to use new materials or to
implement new structural systems. Fiber Reinforced Polymer (FRP)
composites have continued to play an important role in solving some
of persistent problems in infrastructure applications because of its
high specific strength, light weight, and durability. In this study, the
concept of the hybrid FRP-concrete structural systems is applied to a
bridge superstructure. The hybrid FRP-concrete bridge superstructure
is intended to have durable, structurally sound, and cost effective
hybrid system that will take full advantage of the inherent properties
of both FRP materials and concrete. In this study, two hybrid FRP-concrete
bridge systems were investigated. The first system consists
of trapezoidal cell units forming a bridge superstructure. The second
one is formed by arch cells. The two systems rely on using cellular
components to form the core of the bridge superstructure, and an
outer shell to warp around those cells to form the integral unit of the
bridge. Both systems were investigated analytically by using finite
element (FE) analysis. From the rigorous FE studies, it was
concluded that first system is more efficient than the second.
Abstract: Elastomeric polymer foam has been used widely in
the automotive industry, especially for isolating unwanted vibrations.
Such material is able to absorb unwanted vibration due to its
combination of elastic and viscous properties. However, the ‘creep
effect’, poor stress distribution and susceptibility to high
temperatures are the main disadvantages of such a system.
In this study, improvements in the performance of elastomeric
foam as a vibration isolator were investigated using the concept of
Foam Filled Fluid (FFFluid). In FFFluid devices, the foam takes the
form of capsule shapes, and is mixed with viscous fluid, while the
mixture is contained in a closed vessel. When the FFFluid isolator is
affected by vibrations, energy is absorbed, due to the elastic strain of
the foam. As the foam is compressed, there is also movement of the
fluid, which contributes to further energy absorption as the fluid
shears. Also, and dependent on the design adopted, the packaging
could also attenuate vibration through energy absorption via friction
and/or elastic strain.
The present study focuses on the advantages of the FFFluid
concept over the dry polymeric foam in the role of vibration isolation.
This comparative study between the performance of dry foam and the
FFFluid was made according to experimental procedures. The paper
concludes by evaluating the performance of the FFFluid isolator in
the suspension system of a light vehicle. One outcome of this
research is that the FFFluid may preferable over elastomer isolators
in certain applications, as it enables a reduction in the effects of high
temperatures and of ‘creep effects’, thereby increasing the reliability
and load distribution. The stiffness coefficient of the system has
increased about 60% by using an FFFluid sample. The technology
represented by the FFFluid is therefore considered by this research
suitable for application in the suspension system of a light vehicle.
Abstract: This paper presents a rheological model for producing
shape-memory thermoplastic polymers. Shape-memory occurs as a
result of internal rearrangement of the structural elements of a
polymer. A non-linear viscoelastic model was developed that allows
qualitative and quantitative prediction of the stress-strain behavior of
shape-memory polymers during heating. This research was done to
develop a technique to determine the maximum possible change in
size of shape-memory products during heating. The rheological
model used in this work was particularly suitable for defining process
parameters and constructive parameters of the processing equipment.
Abstract: It is an established fact that polymers have several
physical limitations such as low stiffness and low resistance to
impact on loading. Hence, polymers do not usually have requisite
mechanical strength for application in various fields. The
reinforcement by high strength fibers provides the polymer
substantially enhanced mechanical properties and makes them more
suitable for a large number of diverse applications. This research
evaluates the effects of particulate Cow bone and Groundnut shell
additions on the mechanical properties and microstructure of cow
bone and groundnut shell reinforced epoxy composite in order to
assess the possibility of using it as a material for engineering
applications. Cow bone and groundnut shell particles reinforced with
epoxy (CBRPC and GSRPC) was prepared by varying the cow bone
and groundnut shell particles from 0-25 wt% with 5 wt% intervals. A
Hybrid of the Cow bone and Groundnut shell (HGSCB) reinforce
with epoxy was also prepared. The mechanical properties of the
developed composites were investigated. Optical microscopy was
used to examine the microstructure of the composites. The results
revealed that mechanical properties did not increase uniformly with
additions in filler but exhibited maximum properties at specific
percentages of filler additions. From the Microscopic evaluation, it
was discovered that homogeneity decreases with increase in % filler,
this could be due to poor interfacial bonding.
Abstract: We report herein the development and preliminary mechanical characterization of fully-dense multi-wall carbon nanotube (MWCNT)-reinforced ceramics and glasses based on a completely new methodology termed High Shear Compaction (HSC). The tubes are introduced and bound to the matrix grains by aid of polymeric binders to form flexible green bodies which are sintered and densified by spark plasma sintering to unprecedentedly high densities of 100% of the pure-matrix value. The strategy was validated across a PyrexTM glass / MWCNT composite while no identifiable factors limit application to other types of matrices. Nondestructive evaluation, based on ultrasonics, of the dynamic mechanical properties of the materials including elastic, shear and bulk modulus as well as Poisson’s ratio showed optimum property improvement at 0.5 %wt tube loading while evidence of nanoscalespecific energy dissipative characteristics acting complementary to nanotube bridging and pull-out indicate a high potential in a wide range of reinforcing and multifunctional applications.
Abstract: It is the worldwide problem that the recycled PVB is
not recycled and it is wildly stored in landfills. However, PVB has
similar chemical properties such as PVC. Moreover, both of these
polymers are plasticized. Therefore, the study of thermal properties
of plasticized PVC and the recycled PVB obtained by recycling of
windshields is carried out. This work has done in order to find nondegradable
processing conditions applicable for both polymers.
Tested PVC contained 38% of plasticizer diisononyl phthalate
(DINP) and PVB was plasticized with 28% of triethylene glycol,
bis(2-ethylhexanoate) (3GO). The thermal and thermo-oxidative
decomposition of both vinyl polymers are compared by calorimetric
analysis and by tensile strength analysis.
Abstract: In contrast with literal meaning of nano, researchers
have been achieved mega adventures in this area and every day more
nanomaterials are being introduced to the market. After long time
application of fossil-based plastics, nowadays accumulation of their
waste seems to be a big problem to the environment. On the other
hand, mankind has more attention to safety and living environment.
Replacing common plastic packaging materials with degradable ones
that degrade faster and convert to non-dangerous components like
water and carbon dioxide have more attractions; these new materials
are based on renewable and inexpensive sources of starch and
cellulose. However, the functional properties of them do not suitable
for packaging. At this point, nanotechnology has an important role.
Utilizing of nanomaterials in polymer structure will improve
mechanical and physical properties of them; nanocrystalline cellulose
(NCC) has this ability. This work has employed a chemical method to
produce NCC and starch bio nanocomposite containing NCC. X-Ray
Diffraction technique has characterized the obtained materials.
Results showed that applied method is a suitable one as well as
applicable one to NCC production.
Abstract: In order to use bitumen in hot mix asphalt, it must
have specific characteristics. There are some methods to reach these
properties. Using polymer modifiers are one of the methods to
modify the bitumen properties. In this paper the effect of Styrene-
Butadiene-Rubber that is one of the bitumen polymer modifiers on
rheology properties of bitumen is studied. In this regard, the
rheological properties of base bitumen and the modified bitumen with
3, 4, and 5 percent of Styrene-Butadiene-Rubber (SBR) were
analysed. The results show that bitumen modified with 5 percent of
SBR has the best performance than the other samples.
Abstract: The polymer foil used for manufacturing of
laminated glass members behaves in a viscoelastic manner with
temperature dependance. This contribution aims at incorporating
the time/temperature-dependent behavior of interlayer to our earlier
elastic finite element model for laminated glass beams. The model
is based on a refined beam theory: each layer behaves according
to the finite-strain shear deformable formulation by Reissner and
the adjacent layers are connected via the Lagrange multipliers
ensuring the inter-layer compatibility of a laminated unit. The
time/temperature-dependent behavior of the interlayer is accounted
for by the generalized Maxwell model and by the time-temperature
superposition principle due to the Williams, Landel, and Ferry.
The resulting system is solved by the Newton method with
consistent linearization and the viscoelastic response is determined
incrementally by the exponential algorithm. By comparing the model
predictions against available experimental data, we demonstrate that
the proposed formulation is reliable and accurately reproduces the
behavior of the laminated glass units.
Abstract: Polymer Electrolyte Membrane Fuel Cell (PEMFC) is
such a time-vary nonlinear dynamic system. The traditional linear
modeling approach is hard to estimate structure correctly of PEMFC
system. From this reason, this paper presents a nonlinear modeling of
the PEMFC using Neural Network Auto-regressive model with
eXogenous inputs (NNARX) approach. The multilayer perception
(MLP) network is applied to evaluate the structure of the NNARX
model of PEMFC. The validity and accuracy of NNARX model are
tested by one step ahead relating output voltage to input current from
measured experimental of PEMFC. The results show that the obtained
nonlinear NNARX model can efficiently approximate the dynamic
mode of the PEMFC and model output and system measured output
consistently.
Abstract: The structures obtained with the use of sandwich
technologies combine low weight with high energy absorbing
capacity and load carrying capacity. Hence, there is a growing and
markedly interest in the use of sandwiches with aluminum foam core
because of very good properties such as flexural rigidity and energy
absorption capability. In the current investigation, the static threepoint
bending tests were carried out on the sandwiches with
aluminum foam core and glass fiber reinforced polymer (GFRP)
skins at different values of support span distances aiming the analyses
of their flexural performance. The influence of the core thickness and
the GFRP skin type was reported in terms of peak load and energy
absorption capacity. For this purpose, the skins with two different
types of fabrics which have same thickness value and the aluminum
foam core with two different thicknesses were bonded with a
commercial polyurethane based flexible adhesive in order to combine
the composite sandwich panels. The main results of the bending tests
are: force-displacement curves, peak force values, absorbed energy,
collapse mechanisms and the effect of the support span length and
core thickness. The results of the experimental study showed that the
sandwich with the skins made of S-Glass Woven fabrics and with the
thicker foam core presented higher mechanical values such as load
carrying and energy absorption capacities. The increment of the
support span distance generated the decrease of the mechanical
values for each type of panels, as expected, because of the inverse
proportion between the force and span length. The most common
failure types of the sandwiches are debonding of the lower skin and
the core shear. The obtained results have particular importance for
applications that require lightweight structures with a high capacity
of energy dissipation, such as the transport industry (automotive,
aerospace, shipbuilding and marine industry), where the problems of
collision and crash have increased in the last years.
Abstract: An experimental and analytical research on shear
buckling of a comparably large polymer composite I-section is
presented. It is known that shear buckling load of a large span
composite beam is difficult to determine experimentally. In order to
sensitively detect shear buckling of the tested I-section, twenty strain
rosettes and eight displacement sensors were applied and attached on
the web and flange surfaces. The tested specimen was a pultruded
composite beam made of vinylester resin, E-glass, carbon fibers and
micro-fillers. Various coupon tests were performed before the shear
buckling test to obtain fundamental material properties of the Isection.
An asymmetric four-point bending loading scheme was
utilized for the shear test. The loading scheme resulted in a high shear
and almost zero moment condition at the center of the web panel. The
shear buckling load was successfully determined after analyzing the
obtained test data from strain rosettes and displacement sensors. An
analytical approach was also performed to verify the experimental
results and to support the discussed experimental program.
Abstract: The model tests were conducted in the laboratory
without and with Plastic recycled polymer in fly ash steep slopes
overlaying soft foundation soils like fly ash and powai soil in order to
check the stability of steep slope. In this experiment, fly ash is used
as a filling material and Plastic Recycled Polymers of diameter =
3mm and length = 4mm were made from waste plastic product (lower
grade plastic product). The properties of fly ash and Plastic recycled
polymers are determined. From the experiments, load and settlement
have measured. From these data, load –settlement curves have
reported. It has been observed from test results that load carrying
capacity of mixture fly ash with Plastic Recycled Polymers slope is
more than that of fly ash slope. The deformation of Plastic Recycled
Polymers slope is slightly more than that of fly ash slope. A Finite
Element Method (F.E.M.) was also evaluated using PLAXIS 3D
version. The failure pattern, deformations and factor of safety are
reported based on analytical programme. The results from
experimental data and analytical programme are compared and
reported.
Abstract: Fly ash (FA) thanks to the significant presence of SiO2
and Al2O3 as the main components is a potential raw material for
geopolymers production. Mechanical activation is a method for
improving FA reactivity and also the porosity of final mixture; those
parameters can be analysed through sorption properties. They have
direct impact on the durability of fly ash based geopolymer mortars.
In the paper, effect of FA fineness on sorption properties of
geopolymers based on sodium silicate, as well as relationship
between fly ash fineness and apparent density, compressive and
flexural strength of geopolymers are presented. The best results in the
evaluated area reached the sample H1, which contents the highest
portion of particle under 20μm (100% of GFA). The interdependence
of individual tested properties was confirmed for geopolymer
mixtures corresponding to those in the cement based mixtures: higher
is portion of fine particles < 20μm, higher is strength, density and
lower are sorption properties. The compressive strength as well as
sorption parameters of the geopolymer can be reasonably controlled
by grinding process and also ensured by the higher share of fine
particle (to 20μm) in total mass of the material.
Abstract: This study is about the structural transformations of
aluminium examining with the Dynamic Mechanical Thermal
Analyzer (DMTA). It is a faster and simpler measuring method to
make consequence about the metal’s structural transformations. The
device measures the changing of the mechanical characteristics
depending on the heating rate, and concludes certain transformations.
This measuring method fast and shows clean-cut results comparing
the conventional ways.
Applying polymer measuring devices for metal investigations is
not widespread method. One of the adaptable ways is shown in this
study. The article compares the results of the small specimen test and
the DMTA method, considering the temperature and the forming
dependence of recrystallization temperature.
Abstract: The main objective of incorporating natural fibers such as Henequen microfibers (NF) into the High Density Polyethylene (HDPE) polymer matrix is to reduce the cost and to enhance the mechanical as well as other properties. The Henequen microfibers were chopped manually to 5-7mm in length and added into the polymer matrix at the optimized concentration of 8 wt %. In order to facilitate the link between Henequen microfibers (NF) and HDPE matrix, coupling agent such as Glycidoxy (Epoxy) Functional Methoxy Silane (GPTS) at various concentrations from 0.1%, 0.3%, 0.5%, 0.7%, 0.9% and 1% by weight to the total fibers were added. The tensile strength of the composite increased marginally while % elongation at break of the composites decreased with increase in silane loading by wt %. Tensile modulus and stiffness observed increased at 0.9 wt % GPTS loading. Flexural as well as impact strength of the composite decreased with increase in GPTS loading by weight %. Dielectric strength of the composite also found increased marginally up to 0.5wt % silane loading and thereafter remained constant.
Abstract: The paper is focused on the identification of limiting
environmental factors of individual industrial floors on which newly
developed polymer protection and repair systems with the use of
secondary raw materials will be used. These mainly include floors
with extreme stresses and special requirements for materials used. In
relation to the environment of a particular industrial floor, it is
necessary to ensure, for example, chemical stability, resistance to
higher temperatures, resistance to higher mechanical stress, etc. for
developed materials, which is reflected in the demands for the
developed material systems. The paper describes individual
environments and, in relation to them, also requirements for
individual components of the developed materials and for the
developed materials as a whole.
Abstract: Forward Osmosis (FO) polyamide thin-film composite
membranes have been prepared by interfacial polymerization using
commercial UF polyethersulfoneas membrane support. Different
interfacial polymerization times (10s, 30s and 60s) in the organic
solution containing trimesoyl chloride (TMC) at constant m-phenylenediamine
(MPD) concentration (2% w/v) were studied. The
synthesized polyamide membranes then tested for treatment of
natural organic matter (NOM) and compared to commercial Cellulose
TriAcetate (CTA) membrane. It was found that membrane prepared
with higher reaction time (30s and 60s) exhibited better membrane
performance (flux and humic acid removal) over commercial CTA
membrane.
Abstract: This paper presents effects of distilled water, seawater
and sustained bending strains of 30% and 50% ultimate strain at
room temperature, on the durability of unidirectional pultruded
carbon fiber reinforced polymer (CFRP) plates. In this study,
dynamic mechanical analyzer (DMA) was used to investigate the
synergic effects of the immersions and bending strains on the viscoelastic
properties of (CFRP) such as storage modulus, tan delta and
glass transition temperature. The study reveals that the storage
modulus and glass transition temperature increase while tan delta
peak decreases in the initial stage of both immersions due to the
progression of curing. The storage modulus and Tg subsequently
decrease and tan delta increases due to the matrix plasticization. The
blister induced damages in the unstrained seawater samples enhance
water uptake and cause more serious degradation of Tg and storage
modulus than in water immersion. Increasing sustained bending
decreases Tg and storage modulus in a long run for both immersions
due to resin matrix cracking and debonding. The combined effects of
immersions and strains are not clearly reflected due to the statistical
effects of DMA sample sizes and competing processes of molecular
reorientation and postcuring.
Abstract: The biodegradable family of polymers
polyhydroxyalkanoates is an interesting substitute for convectional
fossil-based plastics. However, the manufacturing and environmental
impacts associated with their production via intracellular bacterial
fermentation are strongly dependent on the raw material used and on
energy consumption during the extraction process, limiting their
potential for commercialization. Industrial wastewater is studied in
this paper as a promising alternative feedstock for waste valorization.
Based on results from laboratory and pilot-scale experiments, a
conceptual process design, techno-economic analysis and life cycle
assessment are developed for the large-scale production of the most
common type of polyhydroxyalkanoate, polyhydroxbutyrate.
Intracellular polyhydroxybutyrate is obtained via fermentation of
microbial community present in industrial wastewater and the
downstream processing is based on chemical digestion with
surfactant and hypochlorite. The economic potential and
environmental performance results help identifying bottlenecks and
best opportunities to scale-up the process prior to industrial
implementation. The outcome of this research indicates that the
fermentation of wastewater towards PHB presents advantages
compared to traditional PHAs production from sugars because the
null environmental burdens and financial costs of the raw material in
the bioplastic production process. Nevertheless, process optimization
is still required to compete with the petrochemicals counterparts.