Abstract: Overhead electrical insulators form an important link in an electric power system. Along with the traditional insulators (i.e. glass and porcelain, etc) presently the polymeric insulators are also used world widely. These polymeric insulators are very sensitive to various environmental parameters such temperature, environmental pollution, UV-radiations, etc. which seriously effect their electrical, chemical and hydrophobic properties. The UV radiation level in the central region of Saudi Arabia is high as compared to the IEC standard for the accelerated aging of the composite insulators. Commonly used suspension type of composite EPDM (Ethylene Propylene Diene Monomer) insulator was subjected to accelerated stress aging as per modified IEC standard simulating the inland arid deserts atmospheric condition and also as per IEC-61109 standard. The hydrophobic characteristics were studied by measuring the contact angle along the insulator surface before and after the accelerated aging of the samples. It was found that EPDM insulator loses it hydrophobic properties proportional to the intensity of UV irradiations and its rate of recovery is also very low as compared to Silicone Rubber insulator.KeywordsEPDM, composite insulators, accelerated aging, hydrophobicity, contact angle.
Abstract: Polypropylene blended with natural oil and pigment additives has been studied. Different formulations for each compound were made into polybag used for cultivation of oil palm seedlings for strength and mechanical properties studies. One group of sample was exposed under normal sunlight to initiate degradation and another group of sample was placed under shaded area for five months. All samples were tested for tensile strength to determine the degradation effects. The tensile strength of directly exposed sunlight samples and shaded area showed up to 50% and 25% degradation respectively. However, similar reduction of Young’s modulus for all samples was found for both exposures. Structural investigations were done using FTIR to detect deformation. The natural additives that were used in the studies were all natural and environmental friendly
Abstract: In this study, hydrogels consisted of polyvinyl alcohol,
propylene glycol and β-glucan were developed by radiation technique
for wound dressing. The prepared hydrogels were characterized by
examining of physical properties such as gel fraction and absorption
ratio. The gel fraction and absorption ratio were dependent on the
crosslinking density. On observing the wound healing of rat skin, the
resulting hydrogels accelerated the wound healing comparing to cotton
gauze. Therefore, the PVA/propylene glycol/β-glucan blended
hydrogels can greatly accelerate the healing without causing irritation.
Abstract: In the present study, the incorporation of graphene
into blends of acrylonitrile-butadiene-styrene terpolymer with
polypropylene (ABS/PP) was investigated focusing on the
improvement of their thermomechanical characteristics and the effect
on their rheological behavior. The blends were prepared by melt
mixing in a twin-screw extruder and were characterized by measuring
the MFI as well as by performing DSC, TGA and mechanical tests.
The addition of graphene to ABS/PP blends tends to increase their
melt viscosity, due to the confinement of polymer chains motion.
Also, graphene causes an increment of the crystallization temperature
(Tc), especially in blends with higher PP content, because of the
reduction of surface energy of PP nucleation, which is a consequence
of the attachment of PP chains to the surface of graphene through the
intermolecular CH-π interaction. Moreover, the above nanofiller
improves the thermal stability of PP and increases the residue of
thermal degradation at all the investigated compositions of blends,
due to the thermal isolation effect and the mass transport barrier
effect. Regarding the mechanical properties, the addition of graphene
improves the elastic modulus, because of its intrinsic mechanical
characteristics and its rigidity, and this effect is particularly strong in
the case of pure PP.
Abstract: This paper deals with the evaluation of flow properties
of polymeric matrix with natural animal fillers. Technical university
of Liberec cooperates on the long-term development of “green
materials“ that should replace conventionally used materials
(especially in automotive industry). Natural fibres (of animal and
plant origin) from all over the world are collected and adapted
(drying, cutting etc.) for extrusion processing. Inside the extruder
these natural additives are blended with polymeric (synthetic and
biodegradable - PLA) matrix and created compound is subsequently
cut for pellets in the wet way. These green materials with unique
recipes are then studied and their mechanical, physical and
processing properties are determined. The main goal of this research
is to develop new ecological materials very similar to unfilled
polymers. In this article the rheological behaviour of chosen natural
animal fibres is introduced considering their shape and surface that
were observed with use of SEM microscopy.
Abstract: Separation of propylene-propane mixture using
immobilized liquid membrane was investigated. The effect of transmembrane
pressure and carrier concentration on membrane
separation performance was studied. It was observed that for 30:70
(vol. %) propylene-propane mixture, at pressure of 120kPa and
carrier concentration of 20wt. %, a separation factor of 474 was
obtained.
Abstract: Transdermal delivery of ondansetron hydrochloride (OdHCl) can prevent the problems encountered with oral ondansetron. In previously conducted studies, effect of amount of polyvinyl pyrrolidone, permeation enhancer and casting solvent on the physicochemical properties on OdHCl were investigated. It is feasible to develop ondansetron transdermal patch by using ethyl cellulose and polyvinyl pyrrolidone with dibutyl pthalate as plasticizer, however, the desired flux is not achieved. The primary aim of this study is to use dimethyl succinate (DMS) and propylene glycol that are not incorporated in previous studies to determine their effect on the physicochemical properties of an OdHCl transdermal patch using ethyl cellulose and polyvinyl pyrrolidone. This study also investigates the effect of permeation enhancer (eugenol and phosphatidylcholine) on the release of OdHCl. The results showed that propylene glycol is a more suitable plasticizer compared to DMS in the fabrication of OdHCl transdermal patch using ethyl cellulose and polyvinyl pyrrolidone as polymers. Propylene glycol containing patch has optimum drug content, thickness, moisture content and water absorption, tensile strength, and a better release profile than DMS. Eugenol and phosphatidylcholine can increase release of OdHCl from the patches. From the physicochemical result and permeation profile, a combination of 350mg of ethyl cellulose, 150mg polyvinyl pyrrolidone, 3% of total polymer weight of eugenol, and 40% of total polymer weight of propylene glycol is the most suitable formulation to develop an OdHCl patch. OdHCl release did not increase with increasing the percentage of plasticiser. DMS 4, PG 4, DMS 9, PG 9, DMS 14, and PG 14 gave better release profiles where using 300mg: 0mg, 300mg: 100mg, and 350mg: 150mg of EC: PVP. Thus, 40% of PG or DMS appeared to be the optimum amount of plasticiser when the above combination where EC: PVP was used. It was concluded from the study that a patch formulation containing 350mg EC, 150mg PVP, 40% PG and 3% eugenol is the best transdermal matrix patch compositions for the uniform and continuous release/permeation of OdHCl over an extended period. This patch design can be used for further pharmacokinetic and pharmacodynamic studies in suitable animal models.
Abstract: In this paper, an automated system is presented for
identification and separation of plastic resins based on near infrared
(NIR) reflectance spectroscopy. For identification and separation
among resins, a "Two-Filter" identification method is proposed that
is capable to distinguish among polyethylene terephthalate (PET),
high density polyethylene (HDPE), polyvinyl chloride (PVC),
polypropylene (PP) and polystyrene (PS). Through surveying effects
of parameters such as surface contamination, sample thickness, label
and cap existence, it was obvious that the "Two-Filter" method has a
high efficiency in identification of resins. It is shown that accurate
identification and separation of five major resins can be obtained
through calculating the relative reflectance at two wavelengths in the
NIR region.
Abstract: This paper presents a part of research on the
rheological properties of bitumen modified by thermoplastic namely
linear low density polyethylene (LLDPE), high density polyethylene
(HDPE) and polypropylene (PP) and its interaction with 80 pen base
bitumen. As it is known that the modification of bitumen by the use
of polymers enhances its performance characteristics but at the same
time significantly alters its rheological properties. The rheological
study of polymer modified bitumen (PMB) was made through
penetration, ring & ball softening point and viscosity test. The results
were then related to the changes in the rheological properties of
polymer modified bitumen. It was observed that thermoplastic
copolymer shows profound effect on penetration rather than
softening point. The viscoelastic behavior of polymer modified
bitumen depend on the concentration of polymer, mixing
temperature, mixing technique, solvating power of base bitumen and
molecular structure of polymer used. PP offer better blend in
comparison to HDPE and LLDPE. The viscosity of base bitumen was
also enhanced with the addition of polymer. The pseudoplastic
behavior was more prominent for HDPE and LLDPE than PP. Best
results were obtained when polymer concentration was kept below
3%
Abstract: Gas chromatography (GC) is the most widely used
technique in analytical chemistry. However, GC has high initial cost
and requires frequent maintenance. This paper examines the
feasibility and potential of using a neural network model as an
alternative whenever GC is unvailable. It can also be part of system
verification on the performance of GC for preventive maintenance
activities. It shows the performance of MultiLayer Perceptron (MLP)
with Backpropagation structure. Results demonstrate that neural
network model when trained using this structure provides an
adequate result and is suitable for this purpose. cm.
Abstract: In this study concept of experimental design is
successfully applied for the determination of optimum condition to
produce PP/SWCNT (Polypropylene/Single wall carbon nanotube)
nanocomposite. Central composite design as one of experimental
design techniques is employed for the optimization and statistical
determination of the significant factors influencing on the tensile
modulus and yield stress as mechanical properties of this
nanocomposite. The significant factors are SWCNT weight fraction
and acid treatment time for functionalizing the nanoparticles.
Optimum conditions are in 0.7 % of SWCNT weight fraction and 210
min as acid treatment time for 1112.75 ± 28 MPa as maximum tensile
modulus and in 216 min and 0.65 % as acid treatment time and
SWCNT weight fraction respectively for 40.26 ± 0.3 MPa as
maximum yield stress. Also after setting new experiments for test
these optimum conditions, found excelent agreement with predicted
values.
Abstract: Reinforced concrete has good durability and excellent structural performance. But there are cases of early deterioration due to a number of factors, one prominent factor being corrosion of steel reinforcement. The process of corrosion sets in due to ingress of moisture, oxygen and other ingredients into the body of concrete, which is unsound, permeable and absorbent. Cracks due to structural and other causes such as creep, shrinkage, etc also allow ingress of moisture and other harmful ingredients and thus accelerate the rate of corrosion. There are several interactive factors both external and internal, which lead to corrosion of reinforcement and ultimately failure of structures. Suitable addition of mineral admixture like silica fume (SF) in concrete improves the strength and durability of concrete due to considerable improvement in the microstructure of concrete composites, especially at the transition zone. Secondary reinforcement in the form of fibre is added to concrete, which provides three dimensional random reinforcement in the entire mass of concrete. Reinforced concrete beams of size 0.1 m X 0.15 m and length 1m have been cast using M 35 grade of concrete. The beams after curing process were subjected to corrosion process by impressing an external Direct Current (Galvanostatic Method) for a period of 15 days under stressed and unstressed conditions. The corroded beams were tested by applying two point loads to determine the ultimate load carrying capacity and cracking pattern and the results of specimens were compared with that of the companion specimens. Gravimetric method is used to quantify corrosion that has occurred.
Abstract: In this research work, poly (acrylonitrile-butadienestyrene)/
polypropylene (ABS/PP) blends were processed by melt
compounding in a twin-screw extruder. Upgrading of the thermal
characteristics of the obtained materials was attempted by the
incorporation of organically modified montmorillonite (OMMT), as
well as, by the addition of two types of compatibilizers;
polypropylene grafted with maleic anhydride (PP-g-MAH) and ABS
grafted with maleic anhydride (ABS-g-MAH). The effect of the
above treatments was investigated separately and in combination.
Increasing the PP content in ABS matrix seems to increase the
thermal stability of their blend and the glass transition temperature
(Tg) of SAN phase of ABS. From the other part, the addition of ABS
to PP promotes the formation of its β-phase, which is maximum at 30
wt% ABS concentration, and increases the crystallization temperature
(Tc) of PP. In addition, it increases the crystallization rate of PP.The
β-phase of PP in ABS/PP blends is reduced by the addition of
compatibilizers or/and organoclay reinforcement. The incorporation
of compatibilizers increases the thermal stability of PP and reduces
its melting (ΔΗm) and crystallization (ΔΗc) enthalpies. Furthermore it
decreases slightly the Tgs of PP and SAN phases of ABS/PP blends.
Regarding the storage modulus of the ABS/PP blends, it presents a
change in their behavior at about 10°C and return to their initial
behavior at ~110°C. The incorporation of OMMT to no compatibilized
and compatibilized ABS/PP blends enhances their storage modulus.
Abstract: This paper presents a research conducted to investigate the effect of mixing process on polypropylene (PP) modified bitumen mixed with well graded aggregate to form modified bituminous concrete mix. Two mode of mixing, namely dry and wet with different concentration of polymer polypropylene was used with 80/100 pen bitumen, to evaluate the bituminous concrete mix properties. Three percentages of polymer varying from 1-3% by the weight of bitumen was used in this study. Three mixes namely control mix, wet mix and dry mix were prepared. Optimum binder content was calculated considering Marshall Stability, flow, air voids and Marshall Quotient at different bitumen content varying from 4% - 6.5% for control, dry and wet mix. Engineering properties thus obtained at the calculated optimum bitumen content revealed that wet mixing process is advantageous in comparison to dry mixing as it increases the stiffness of the mixture with the increase in polymer content in bitumen. Stiffness value for wet mix increases with the increase in polymer content which is beneficial in terms of rutting. 1% PP dry mix also shows enhanced stiffness, with the air void content limited to 4%.The flow behaviour of dry mix doesn't indicate any major difference with the increase in polymer content revealing that polymer acting as an aggregate only without affecting the viscosity of the binder in the mix. Polypropylene (PP) when interacted with 80 pen base bitumen enhances its performance characteristics which were brought about by altered rheological properties of the modified bitumen. The decrease in flow with the increase in binder content reflects the increase in viscosity of binder which induces the plastic flow in the mix. Workability index indicates that wet mix were easy to compact up to desired void ratio in comparison to dry mix samples.
Abstract: Chemical and physical functionalization of multiwalled
carbon nanotubes (MWCNT) has been commonly practiced to
achieve better dispersion of carbon nanotubes (CNTs) in polymer
matrix. This work describes various functionalization methods (acidtreatment,
non-ionic surfactant treatment with TritonX-100),
fabrication of MWCNT/PP nanocomposites via melt blending and
characterization of mechanical properties. Microscopy analysis
(FESEM, TEM, XPS) showed effective purification of MWCNTs
under acid treatment, and better dispersion under both chemical and
physical functionalization techniques combined, in their respective
order. Tensile tests showed increase in tensile strength for the
nanocomposites that contain MWCNTs up to 2 wt%. A decrease in
tensile strength was seen in samples that contain 4 wt% of MWCNTs
for both raw and Triton X-100 functionalized, signifying MWCNT
degradation/rebundling at composition with higher content of
MWCNTs. For the acid-treated MWCNTs, however, the tensile
results showed slight improvement even at 4wt%, indicating effective
dispersion of MWCNTs.
Abstract: The catalytic dehydroxylation of glycerol to propylene
glycol was investigated over Cu-ZnO/Al2O3 prepared by incipient
wetness impregnation (IWI) method with different purity feedstocks -
refined glycerol and technical grade glycerol. The main purpose is to
investigate the effects of feed impurities that cause the catalyst
deactivation. The prepared catalyst were tested for its catalytic
activity and selectivity in a continuous flow fixed bed reactor at 523
K, 500 psig, H2/feed molar ratio of 4 and WHSV of 3 h-1. The results
showed that conversion of refined glycerol and technical grade
glycerol at time on stream 6 hour are 99% and 71% and selectivity to
propylene glycol are 87% and 56% respectively. The ICP-EOS and
TPO results indicated that the cause of catalyst deactivation was the
amount of impurities in the feedstock. The higher amount of
impurities (especially Na and K) the lower catalytic activity.
Abstract: The use of polypropylene mesh devices for Pelvic
Organ Prolapse (POP) spread rapidly during the last decade, yet our
knowledge of the mesh-tissue interaction is far from complete. We
aimed to perform a thorough pathological examination of explanted
POP meshes and describe findings that may explain mechanisms of
complications resulting in product excision. We report a spectrum of
important findings, including nerve ingrowth, mesh deformation,
involvement of detrusor muscle with neural ganglia, and
polypropylene degradation. Analysis of these findings may improve
and guide future treatment strategies.
Abstract: Fluids are used for heat transfer in many engineering
equipments. Water, ethylene glycol and propylene glycol are some
of the common heat transfer fluids. Over the years, in an attempt to
reduce the size of the equipment and/or efficiency of the process,
various techniques have been employed to improve the heat transfer
rate of these fluids. Surface modification, use of inserts and
increased fluid velocity are some examples of heat transfer
enhancement techniques. Addition of milli or micro sized particles
to the heat transfer fluid is another way of improving heat transfer
rate. Though this looks simple, this method has practical problems
such as high pressure loss, clogging and erosion of the material of
construction. These problems can be overcome by using nanofluids,
which is a dispersion of nanosized particles in a base fluid.
Nanoparticles increase the thermal conductivity of the base fluid
manifold which in turn increases the heat transfer rate. In this work,
the heat transfer enhancement using aluminium oxide nanofluid has
been studied by computational fluid dynamic modeling of the
nanofluid flow adopting the single phase approach.
Abstract: Hydrothermally synthesized high silica borosilicates
with the MFI structure was subjected to several characterization
techniques. The effect of boron on the structure and acidity of
HZSM-5 catalyst were studied by XRD, SEM, N2 adsorption, solid
state NMR, NH3-TPD. It was confirmed that boron had entered the
framework in the boron samples. The results also revealed that strong
acidity was weakened and weak acidity was strengthened by the
boron added zeolite framework compared with parent catalyst. The
catalytic performance was carried out in a fixed bed at 460°C for
methanol to propylene (MTP) reaction. The results of MTP reaction
showed a great increment of the propylene selectivity and excellent
stability for the B-HZSM-5. The catalyst exhibited about 81%
selectivity to C2
= - C4
= olefins with 40% selectivity of propylene as
major component at near 100% methanol conversion, and the stable
performance in the studied period was 100h.
Abstract: The separation of dissolved gas including dissolved oxygen can be used in breathing for a human under water. When one is suddenly wrecked or meets a tsunami, one is instantly drowned and cannot breathe under water. To avoid this crisis, when we meet waves, the dissolved gas separated from water by wave is used, while air can be used to breathe when we are about to escape from water. In this thesis, we investigated the separation characteristics of dissolved gas using the pipe type of hollow fiber membrane with polypropylene and the nude type of one with polysulfone. The hollow fiber membranes with good characteristics under water are used to separate the dissolved gas. The hollow fiber membranes with good characteristics in an air are used to transfer air. The combination of membranes with good separation characteristics under water and good transferring one in an air is used to breathe instantly under water to be alive at crisis. These results showed that polypropylene represented better performance than polysulfone under both of air and water conditions.