bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical, Thermal and Rheological Properties of Polypropylene/Wheat Straw Composites and Study of the Effect of Nanoclay on Their Mechanical Properties
Authors: Hashemi S.A. , Esfandeh M. , Mohammadi J.
Published: September 2018

Polymer–wood fibre composites utilize wood fibres as reinforcing filler in the polymer matrix and are advantageous over the pure polymers in terms of the materials cost and some mechanical properties such as modulus and strength. The scope of the present paper is to study the prospects of using wheat straw fibres as a reinforcing filler in polypropylene (PP). Untreated and silane-treated fibres having a variety of fibre lengths were used at various fibre contents to reinforce PP. Composites were tested for their mechanical, thermal and rheological properties, and the assessment of the adhesion at the interface was made via observations by SEM microscopy. The results showed that for untreated fibres, an increase in fibre content up to 20% (wt) led to an increase in the tensile strength of the composite. However, beyond this amount, tensile strength decreased. On the other hand, the tensile modulus increased due to higher stiffness of the fibres. By using silane treated fibres, both tensile strength and modulus increased, but the viscosity was reduced because of better dispersion of the treated fibres. By the addition of nano-clay, the mechanical properties of the composites, compared to the pure polymer, increased up to a certain fibre content, and after that the trend was reversed.
Preparation of Thermoplastic Elastomer from Epoxidised Natural Rubber and Polystyrene
Authors: Chuayjujit S. , Sakulkijpiboon S. , Potiyaraj P.
Published: September 2018

The aim of this research was to prepare and investigate the behaviour of thermoplastic elastomers (TPE) from epoxidised natural rubbers (ENR) blended with polystyrene. ENRs with different amounts of epoxide groups were prepared via in situ epoxidation method and denoted accordingly as ENR25, ENR35 and ENR50. Polystyrene (PS) was prepared by emulsion polymerisation. The obtained ENRs were blended with commercial and prepared PS at room temperature in the latex state at the amounts of dry PS of 0, 20, 40, 60, 80 and 100 phr (parts per hundred rubber). The mechanical and thermal properties of the blend sheets were investigated. It was found that the tensile strength and elongation at break increased as the amount of PS increased, then decreased later at higher amounts of PS. However, these values decreased as the amount of epoxide groups increased. The hardness of the specimens increased with the increase of epoxide groups and PS content. For the determination of blend compatibility, a shift in glass transition temperature to a lower temperature was revealed by DSC analysis. According to the results, the ENR/PS blends could be described as partially miscible blends.
Low-velocity Impact Behaviour of 3-D Glass Fibre Hollow Integrated Core Sandwich Composites
Authors: Cao Haijian , Qian Kun , Wei Qufu , Li Hongshun
Published: September 2018

In the current work, 3-D glass fibre woven fabric-reinforced composites were fabricated by impregnating epoxy resin in a hand lay-up procedure for the hollow integrated core sandwich structure. Four types of 3-D structures were investigated in terms of the impact properties as a function of the z-direction fibre length (5, 6 and 7 mm) and covered skins (covered with aluminium) in core structures. Impact properties including peak load, time to peak load, and absorbed energy were evaluated. It was found that the 3-D hollow integrated core sandwich composites covered with aluminium skin considerably enhanced the impact resistance. Photographs of the impact damage taken after impact tests were analyzed and discussed in terms of a hollowing on the front face sheet against the load applied, and whitening spread in the impact point on the back face sheet of the composites was also studied.
Effect of Process Parameters on Layer-by-layer Self-assembly of Polyelectrolytes on Cotton Substrate
Authors: Ali S. Wazed , Rajendran S. , Joshi Mangala
Published: September 2018

To our knowledge, the present study is the first attempt to evaluate the effect of different process parameters on the amount of polyelectrolyte adsorbed on a cotton textile substrate via sequential adsorption of negatively charged poly (styrene sulfonate) (PSS) and positively charged poly (allylamine hydrochloride) (PAH) using layer-by-layer (LBL) self-assembly nanocoating process. A considerably different polymer adsorption behaviour was observed from thick adsorbed layers to thin adsorbed layer with different degree of layer penetration and ionic pair formation over the pH range (2.5 – 9.0) studied. The amount of polyelectrolyte adsorption on cotton fabric was evaluated by measuring the colour value (K/S) of methylene blue absorbed cotton surface. Contact angle measurement revealed that the extent of binding of the oppositely charged polyions on the fabric depends on the pH of the polyelectrolyte solution and ‘zipped-up’ structure with more ion pair formation was observed at the pH range 4.5 – 6.5. At higher temperature, the amount of polyelectrolyte adsorbed within the multilayers was higher. An increased deposition of PSS and PAH was observed with increase in electrolyte (NaCl) concentration. The amount of PSS and PAH adsorption increased up to 0.03 (M) of PSS and 0.01 (M) of PAH concentrations, respectively. A dipping time of 5 min was sufficient to have a maximum deposition of the polyelectrolyte multilayers.
Computer Simulation of Resin Flow through the Bleeder in the Autoclave Curing Process
Authors: Xu Peijun , Jing Xinli
Published: September 2018

In the autoclave curing process of phenolic resin composite at high pressure, uncured resin usually flows into the vacuum pipe through improperly used bleeder and blocks the vacuum orifice. Therefore, there are too many defects formed in the as-prepared composite because not all volatiles can be expelled from the laminate. In order to choosing or manufacturing the bleeder used in this special condition, the resin flow in the bleeder should be carefully investigated. However, the resin flow in the bleeder cannot be observed directly during the autoclave curing process, computer simulation is employed to describe the flow in the bleeder. The simulation results show that i) the resin flow near the vacuum orifice is quite different compared to that far away from the vacuum orifice, the resin can flow through the bleeder near the vacuum orifice within a shorter time; ii) a bleeder made from needle-punched nonwoven material with low porosity, small fibre diameter and small permeability could prevent the resin from flowing into the vacuum pipe in the autoclave curing process.
Synthesis of Hyper-branched 4A Zeolite and its Application in Natural Rubber Systems
Authors: Jincheng Wang , Xiaoyu Zheng , Yuehui Chen
Published: September 2018

Hyper-branched 4A zeolite (HB-4A zeolite) was prepared by condensation reaction between 4A zeolite and the monomer we prepared. It was then characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). This HB-4A zeolite was then used in the preparation of natural rubber (NR)/HB-4A zeolite composite. Different types of NR/HB-4A zeolite composites were prepared with different amounts of HB-4A zeolite and compared with the composites directly incorporated with 4A zeolite. The cure characteristics of different 4A zeolite filled NR composites were studied. Then, the tensile and thermal properties were compared. Results revealed that the mechanical properties of NR/HB-4A zeolite, especially elongation at break, showed a remarkable enhancement compared with that of NR/4A zeolite and NR systems. SEM studies showed that hyper-branching modification might increase the compatibility between 4A zeolite and NR matrix. A reinforcing mechanism was proposed, assuming that the ‘anchor’ effect caused by the hyper-branched polymer may reduce the amount and size of voids and increase the length of the crack spread path during tensile drawing.
Modified PF Resins for Composite Structures with Improved Mechanical Properties
Authors: Cardona F. , Aravinthan T. , Moscou C.
Published: September 2018

Novel composites resins for civil engineering structures were synthesised. Resol phenolic resins were modified by the copolymerization of phenol with cardanol (obtained from CNSL). The modified PF resins were synthesized at different proportions of phenol to cardanol and also of the total phenol to formaldehyde. The synthesis was carried out under alkaline conditions and with a maximum content of 40 wt.% of cardanol. The effect of the partial substitution of phenol by cardanol on the thermal and mechanical properties of the CPF resins was investigated. An increase in the content of cardanol resulted in a proportional increase in the flexibility and in the fracture toughness together with a decrease in the flexural modulus of the cured CPF resins. The higher toughening effect of replacing phenol with cardanol was obtained with the total P:F molar ratio of 1.0:1.25. Also a direct proportionality between the amount of cardanol content and the decrease in crosslink density of the resins was observed. Simultaneous TGA-FTIR studies of the resins were carried out and the emitted gases were identified. The results confirmed that the thermal stability and the temperature of degradation of the cured CPF resins decreased as the amount of cardanol content increased. Gas emissions during the pyrolysis of the CPF resins also increased.
The Effects of Weathering on Mechanical Properties of Kenaf Unsaturated Polyester Composites (KFUPC)
Authors: Rashdi A.A.A. , Sapuan S.M. , Ahmad M.M.H.M. , Khalina A.
Published: September 2018

Exposure to natural weathering changes the mechanical properties of unsaturated polyester composites. These changes can negatively affect the mechanical properties of natural fibre composites, through UV radiation and relative humidity. The idea of this study was to determine the durability of kenaf unsaturated polyester composites (KFUPC) in natural conditions, and in addition, to determine the effects of weathering on the performance of these composites and the biodegradability possessed by the composite when exposed to natural weather. KFUPC composites were exposed to the atmosphere for four months. Humidity up-take tests were performed on composite specimens containing (10%, 20% and 30%) weight percentage of fibre content. The tensile properties of exposed specimens were evaluated, and compared alongside dry composite specimens. A decrease in tensile properties of the weather exposed composites was demonstrated, compared with the dry samples. The percentage of moisture uptake increased as the weight percentage of fibre increased, due to the high cellulose content.
Preparation of Recycled Polyvinyl Alcohol) (PVA)/Iodine Polarizing Film
Authors: Han Man Ho , Shin Jae Kyun , Oh Kyeong Il , Lee Young Jae , Song Du Hyun , Chung Yong Sik , Lee Yong Rok , Choi Han Gon , Oh Tae Hwan , Han Sung Soo , Noh Seok Kyun , Lyoo Won Seok
Published: September 2018

To precisely identify the effect of preparation conditions on the polarizing efficiency (PE) of recycled poly(vinyl alcohol) (PVA)/iodine complex film, PVA film and PVA/iodine polarizing film were prepared by using recycled nonwoven PVA with a number-average degree of polymerization (Pn) of 1700, syndiotactic diad (s-diad) content 54.6%, and degree of saponification (DS) 97.6%. We investigated the effects of various conditions such as soaking time, temperature of I2/KI aqueous solution, draw ratio, and temperature of aqueous boric acid solution on the transmittance and PE of recycled PVA/iodine complex film. Maximum transmittance and PE values of recycled PVA/iodine complex film were 41.2% and 99.8%, respectively. It was found that the recycled PVA/iodine polarizing film showed effective transmittance and PE values comparable with those of commercial PVA/iodine polarizing film.
Electrical and Dielectric Properties of Multi-Walled Carbon Nanotube Filled Polypropylene Nanocomposites
Authors: Prashantha K. , Soulestin J. , Lacrampe M.F. , Krawczak P. , Dupin G. , Claes M. , Tewari A.
Published: September 2018

Different concentrations of multi-wall carbon nanotubes (MWNTs) filled polypropylene (PP) nanocomposites were prepared through PP/MWNT masterbatch dilution process by melt compounding with a twin-screw extruder. Prepared nanocomposites were characterized for their electrical resistivity and dielectric properties. The experimental results revealed that incorporation of MWNTs in PP matrix had decreased the electrical resistivity and increased the dielectric constant at low dielectric loss. The electrical conductivity and dielectric constant of PP/MWNT nanocomposites increased significantly near the percolation thresholds, which is equal to 2 wt.% of MWNTs. The PP nanocomposite containing 5 wt.% MWNT exhibited a high dielectric constant under wide sweep frequencies attended by low dielectric loss. Its dielectric constant is >110 under lower frequency, and remains the same in the entire frequency range. Interestingly, dielectric constant values of the prepared nanocomposite systems have weak or nil frequency dependence in the entire frequency range. Morphological characterization was done using scanning electron microscopy (SEM) and it was observed that nanotubes are distributed reasonably uniformly indicating a good dispersion of nanotubes in the PP matrix. The obtained results indicate that a common commercial plastic with good comprehensive performance, which exhibited the potential for applications in advanced electronics, was obtained by a simple industry benign technique.
Effect of Reactive Diluents and Kaolin on the Mechanical Properties of Epoxy Resin
Authors: Bakar M. , Szymańska J. , Rudecka J. , Fitas J.
Published: September 2018

Epoxy resin was modified using phenyl diglycidyl ether (PGE), xylene and kaolin. The impact strength (IS), critical stress intensity factor (K), flexural strength and glass transition temperature (Tg) were evaluated as functions of the modifier content. It was found that the addition of diluents led to a significant reduction of both viscosity and Tg. A three-fold increase of IS was obtained with the addition of 2.5% PGE. Moreover, the addition of 15% PGE resulted in about 145% enhancement of the KC parameter. However, the addition of xylene had no significant effect on these properties. Furthermore, the addition of 10% kaolin to epoxy resin gave compositions with the highest fracture toughness. Maximum KC values were obtained with epoxy hybrid compositions containing 10% kaolin and 2.5% PGE and 10% kaolin and 5% PGE respectively. All tested compositions had higher energy at break than nonmodified epoxy resin. SEM micrographs of fractured surfaces of modified epoxy compositions revealed the presence of plastic deformations, which can be considered as the main source of the mechanical properties enhancement.
Flow Instability of Polyvinyl alcohol)/Dimethyl Sulfoxide Solution under Steady Shear
Authors: Do Sung Yeol , Ryu Chang Yeol , Lee Yong Rok , Shim Jae Jin , Noh Seok Kyun , Kim Joon Ho , Joo Sang Woo , Gal Yeong Soon , Han Sung Soo , Lyoo Won Seok
Published: September 2018

The effects of solution temperature and molecular weight on the rheological responses of poly(vinyl alcohol) (PVA) semidilute solutions (13 g/dL- 19 g/dL) in dimethyl sulfoxide (DMSO) have been studied using PVA with two different number-average degrees of polymerization (Pn): 1700 and 4000. For the rheological experiments using dynamic shear, the PVA solution with a Pn of 1700 showed rather simple Newtonian fluid behaviour, whereas that with Pn of 4000 exhibited non-Newtonian shear thinning behaviour. Steady shear rheology experiments suggested that the lower Pn PVA solutions were Newtonian fluids, which is consistent with the dynamic shear rheology results. However, an abrupt decrease of shear viscosity at high shear rates was observed for the higher Pn PVA solutions at lower temperatures, such as 30 °C and 50 °C. At higher temperatures of 70 °C and 90 °C, the higher molecular weight PVA solutions exhibited simple shear thinning behaviour without any further complications of flow instability. The fact that temperature plays a critical role in controlling the observed flow instability of the PVA solutions in DMSO strongly suggests that there exist enhanced inter-chain interactions by hydrogen bonding of PVA chains beyond the chain entanglements, particularly for the higher Pn PVA semidilute solutions at low temperatures. Therefore, it is important to consider both chain entanglements and hydrogen bonding interactions in order to process PVA solutions without causing undesirable flow instability.
Preparation and Characterization of Polyethylene Terephthalate)/Boehmite Nanocomposites
Authors: Zhang Jianjun , Ji Quan , Zhang Ping , Kong Qingshan , Xia Yanzhi
Published: September 2018

The morphology, flame retardancy and non-isothermal crystallization behaviour of pure PET and poly(ethylene terephthalate)/nano-boehmite composites (PET/AlOOH) prepared in situ were characterized using several techniques. The morphology of the nanocomposites carried out using transmission electron microscopy (TEM) showed that the nano-boehmite particles were uniformly dispersed in the polymer matrix and formed crosslinked structures. Combustion behaviour and flammability were assessed using cone calorimetry (CONE). The results indicated that the total heat release (THR) and smoke production rate of PET/AlOOH were significantly less than those of pure PET. Study of the behaviour and kinetics of non-isothermal crystallization of pure PET and PET/AlOOH nanocomposites was accomplished by DSC analysis. The results showed that the AlOOH could act as an effective nucleation agent for the crystallization of PET, while the presence of boehmite decreased the crystallization rate and extended the time of crystallization of PET, which can be explained by the formation of partly-crosslinked structure of PET/AlOOH nanocomposites.
Combustion Behaviour and Synergistic Effect of Zinc Borate and Microencapsulated Red Phosphorus with Magnesium Hydroxide in Flame-Retarded Polypropylene Composites
Authors: Chen Xiaolang , Yu Jie , Qin Jun , Luo Zhu , Hu Shuchun , He Min
Published: September 2018

In this paper, the limiting oxygen index (LOI), Underwriters’ Laboratories-94 (UL-94) test, cone calorimeter test (CCT), and thermogravimetric analysis (TGA) were used to study the flame-retardant properties of polypropylene (PP) composites and the synergistic flame-retardant effects of zinc borate (ZB) and/or microencapsulated red phosphorus (MRP) with modified magnesium hydroxide (MH) on PP. The experimental results showed that the addition of ZB and MRP had a great effect on the flammability of the PP composites. The data obtained from the CCT indicated that the heat release rate (HRR), the effective heat of combustion (EHC), and the mass loss of the flame-retarded PP composites decreased markedly with increasing addition of ZB and/or MRP. The data obtained from the TGA curves indicated that the thermal stabilities of PP/MH/ZB and PP/MH/ZB/MRP composites were better than those of PP/MH composites.
Low Energy Impact Indentation of an Epoxy-Carbon Fiber Laminate
Authors: Martínez A.B. , Xiang G. , Arencón D. , Velasco J.I.
Published: September 2018

The impact event involves the motion of the specimen, the motion of the striker and the local indentation in the contact zone. In order to study the effect of the local indentation, epoxy-carbon fiber laminate specimens supported on a very rigid steel plate, were subjected to low energy impacts in an instrumented falling weight dotted with an instrumented striker with an hemispherical head. The obtained restitution coefficients show that the energy absorption by indentation is not negligible. It has been developed a lumped mass spring model based in the Hertz law which agrees with the experimental contact forces, indenter displacements and restitution coefficient, which give a very good fitting. This non-conservative model allowed assessment of the Young's modulus at these relatively high strain rates.
Characterization of Chitosan-Hyaluronic Acid Blended Membranes and Their Effects on the Growth of Keratocytes
Authors: Yao Zi-Ang , Wu Hai-Ge
Published: September 2018

In order to construct a suitable scaffold for corneal cell culture and transplantation in vitro, various chitosan-hyaluronic acid blended membranes were prepared, and the properties of the blended membranes were studied. Rabbit keratocytes were seeded onto the blended membrane surfaces and the effects of the blended membranes on cell attachment and metabolism were investigated. The results showed that chitosan and hyaluronic acid (HA) were compatible in blended membranes. HA improved the homogeneity, crystallization and transparency, and decreased the tensile strength and hydrophilicity of blended membranes within the blending ratio of 1:0.05. Under the blending ratio of 1:0.02, HA reduced the harm that the chitosan membrane caused the cells and improved the biocompatibility between cells and membranes. Rabbit keratocytes grew and formed a confluent monolayer on the chitosan-hyaluronic acid blended membrane within a blending ratio of 1:0.02. All the results indicated that chitosan and HA were compatible within the blending ratio of 1:0.02, and the blended membranes had homogeneous structure, suitable physicochemical properties and biocompatibility with cells, this implied that the blended membranes could be used as a scaffold for corneal cell culture in vitro and as a potential carrier for corneal endothelial cell transplantation.
Prediction of the Modulus of Elasticity of Short Fibre Reinforced Polymer Composites by Finite Element Modelling
Authors: El-Sabbagh A. , Taha I. , Taha R.
Published: September 2018

Recently, there has been increased interest in fibre-reinforced polymer composites, due to their distinctive specific strength, corrosion resistance and fatigue resistance, as well as high damping characteristics. In this paper, finite-element models for the prediction of the modulus of elasticity of short-fibre reinforced composites (SFRC) are introduced. The stiffness of a structure is of principal importance in many engineering applications and the modulus of elasticity is often one of the primary properties considered when selecting a material. In the developed models, different factors affecting the overall performance of such composites are considered. These factors include the respective volume fractions of the polymer matrix and fibrous reinforcement, fibre orientation and agglomeration. Three finite-element models with different sophistication levels are proposed. The models are validated by comparing the effective modulus of elasticity predicted by the different models to experimental results obtained by tensile testing SFRC samples consisting of glass fibres in a polypropylene matrix at different volume fractions.
Electrospinning Fabrication of Polyvinyl alcohol)/Waterborne Polyurethane/Silver Composite Nanofibre Mats in Aqueous Solution for Anti-bacterial Exploits
Authors: Park Jae Hyeung , Kim In Kyo , Choi Jae Young , Karim Mohammad Rezaul , Cheong In Woo , Oh Weontae , Yeum Jeong Hyun
Published: September 2018

Nanofibre mats of poly(vinyl alcohol) (PVA), waterborne polyurethane (WBPU) and nanometre silver (Ag) colloids have been fabricated by an electrospinning method in aqueous solutions. Since PVA is a water soluble and biocompatible polymer, it is one of the best materials for preparation of electrospun antibacterial nanofibre mats. WBPU was used as a filler to enhance the properties of homopolymer nanofibre. Transmission electron microscopy analyses showed a uniform distribution of silver in the fibres. In anti-bacterial tests, the PVA/WBPU/Ag composite nanofibres showed excellent anti-bacterial performance, indicating practical uses as a new preservative. Moreover, the PVA/WBPU/Ag nanofibres showed improved thermal properties.
Preparation, Morphology and Properties of Electrospun Lauric Acid/PET Form-Stable Phase Change Ultrafine Composite Fibres
Authors: Cai Yibing , Ke Huizhen , Zhang Tingting , Dong Ju , Qiao Hui , Wang Honglei , xu Zhangfei , Wei Qufu , Zhao Yong , Fong Hao
Published: September 2018

Lauric acid (LA)/polyethylene terephthalate (PET) ultrafine composite fibres as form-stable phase change materials (PCM) were prepared successfully via electrospinning. The morphology, thermal energy storage properties, thermal stability and flammability properties of electrospun LA/PET composite fibres were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC), respectively. It was found by SEM investigation that the average fibre diameter generally increased with increasing content of LA in the LA/PET composite fibres. The morphology of electrospun composite fibres changed from a cylindrical shape with a smooth surface (without LA) to a rough and non-uniform structure (with LA). The DSC measurements indicated that there was little change of the phase transition temperatures of the composite fibres, but there was a decrease of the heat enthalpies compared with the pure lauric acid. The TGA results showed that both the onset thermal degradation temperature and charred residue at 700 °C of composite fibres were lower than those of the pure PET fibres, due to the thermal instability of LA. The MCC tests showed that there were two peaks of heat release rate, which corresponded respectively to combustion of LA and PET in the electrospun composite fibres. It could be also found that the first peak increased and the second peak decreased with increasing LA content in composite fibres.
Preparation and Processing Characterization of Glass/Phenolic Prepregs
Authors: Rajaei Mohammad , Beheshty Mohammad Hosain , Hayaty Mehran
Published: September 2018

Glass/phenolic prepreg is one of the most applicable prepregs used for making composites for structural parts. To investigate the effective parameters on the processing and properties of these prepregs, thirty samples of glass/phenolic prepregs containing about 50 wt.% resins were prepared by using a resole type phenolic resin and satin glass fibre fabric. They were B-staged or pre-cured at 110 °C and 120 °C for different times from 15 to 50 min, to control the flow behaviour and tack properties. Tack and resin flow were characterized, in order to determine the conditions in which flow and tack properties are optimum. Results show that the levels of pre-cure or conversion were between 2% and 55%. The maximum tack was achieved at 5.3% conversion. Cure behaviour and rheological properties of these prepregs were studied by using differential scanning calorimetry and rheometry. An appropriate cure cycle is presented with the aid of these results. After curing the prepregs on the basis of this cure cycle, a flexural strength of 172.6 MPa and flexural modulus of 17 GPa were obtained.
Application of Modified Calcium Sulfate Whisker in Methyl Vinyl Silicone Rubber Composites
Authors: Jincheng Wang , Lijuan Tang , Ding Wu , Xi Guo , Wenli Hao
Published: September 2018

Novel methyl vinyl silicone rubber (MVQ)/calcium sulfate whisker (CSW) composites had been prepared. Two types of modification agents, hydrogen silicone oil and silane coupling agent, were used in the preparation of modified calcium sulfate whiskers (MCSW). The morphology and properties of MCSW were analyzed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Then, the two types of MCSW were applied in the preparation of MVQ composites. Properties such as cure characteristics, tensile strength, elongation at break, permanent distortion and thermal stability were analysed and compared. Results showed that addition of MCSW could improve the tensile and thermal properties of the silicone rubber composites. A combination of SEM studies was used to characterize the structure and reinforcing mechanism of MCSW.
Preparation, Characterization and Study of the Morphological, Mechanical and Thermal Properties of Epoxy/Urethane Interpenetrating Polymer Networks Nanocomposites
Authors: Ghafghazi Mehdi , Esfandeh Masoud , Morshedian Jalil , Ghafghazi Shiva
Published: September 2018

In this study epoxy/urethane (EP/PU) graft interpenetrating polymer networks (g-IPNs) nanocomposites were prepared by a simultaneous polymerization method and the effects of organophilic montmorillonite (Cloisite 30B) content on the mechanical, morphological and thermal properties of the nanocomposites were investigated. Cloisite 30B was dispersed in epoxy resin via a sonication method, after which g-IPN nanocomposites were prepared by thorough mixing of a synthesized isocyanate-terminated urethane pre-polymer with this epoxy resin (EP/PU weight ratio=75/25) followed by simultaneous curing of the resins. Polytetramethylene ether glycol (PTMEG) with molecular weight (Mw) of 3000 g/mol was used to prepare urethane prepolymers. Curing reactions were followed by Fourier Transform Infrared spectroscopy (FT–IR). Wide Angle X-ray diffraction (WAXD) was used to investigate the dispersion of Cloisite 30B in g-IPN nanocomposite specimens. Based on these results, an exfoliated morphology has been suggested for nano IPN specimens containing 1 and 3 wt.% of Cloisite 30B and an intercalated morphology for that with 5 wt.% of Cloisite 30B. Dynamic Mechanical Thermal Analysis (DMTA) was used to determine the glass transition temperature (Tg) of the IPNs. The maximum Tg was observed for the nanocomposite with 3 wt.% of Cloisite 30B. The storage modulus (E′) of nanocomposites increased with increasing clay content. Thermogravimetric Analysis (TGA), tensile measurements and Scanning Electron Microscopy (SEM) were used to study the thermal, mechanical and morphological properties of the prepared specimens. The maximum tensile properties were obtained at 3 wt.% of Cloisite 30B. Furthermore, with increasing clay content, the onset of the thermal degradation temperature was delayed.
Effect of Process Conditions on ILSS of carbon Fiber / Epoxy Composites Stepwise Curing with Low-energy E-Beam
Authors: Zhao Xinming , Duan Yugang , Li Dichen , Zhang Jingjing , Wang Ben
Published: September 2018

Electron beam (E-Beam) curing technology has become increasingly applied in modern composite manufacturing industry. Comparing to conventional thermal curing, E-Beam curing provides an efficient solution to fabricate integrated composite structures of a wide range of dimensions with a minimal consumption of energy. Currently, the majority of E-Beam curing systems use high-energy E-Beams. However, high construction cost, high radiation, and low operational flexibility hinder the further expansion of applications of this technique. In this study, a prototype of novel dual-emitter low-energy E-Beam curing system was built, which was energy efficient and radiation safe. The minimum E-Beam energy that could satisfy the stepwise curing of carbon fiber/epoxy composites was investigated through detailed analysis of effects of the irradiation dose, the post cure temperature, and roller materials on the inter-laminar shear strength (ILSS) with microstructure characteristics. The results indicate that carbon fiber/epoxy (CF/EP) composites can be adequately cured by 150 keV E-Beams using our system, with an optimal irradiation dose which could enhance the ILSS as largely as 44.6 % (from 34.2 MPa to 61.7 MPa). It was also observed that laminates irradiated by 50 kGy and post-cured at 180 °C would reach the optimized ILSS of 64.7 MPa. An anti-sticking silicon rubber with low surface energy could effectively reduce interlayer defects, resulting in higher ILSS.
Numerical Solution of Penetration into Woven Fabric Target Impregnated with Shear Thickening Fluid
Authors: Kordani Naser , Vanini Ali Sadough , Amiri Hosein
Published: September 2018

In this paper, yarn pull-out testing was performed to estimate the pulling-out force and the friction coefficient. Fabrics were impregnated with Shear Thickening Fluid (STF) of two types. Single fibre tensile tests were performed to determine the resistance of each fibre. The speed of pulling out was 500 mm/min and the samples were placed horizontally in a tensile device. The results indicated that the fabric impregnated in STF needed more force in order to get out of the fabric. Friction coefficients of three fabric types of raw fabric, fabric with dissolved fluid and fabric with STF were entered into an explicit dynamics finite element model along with the mechanical characteristic of a yarn. Ballistic range velocity was extracted for samples by the software and was compared with experimental results. The effects of the shear thickening fluid (STF) were considered as frictional effects.
Evaluation of the Mechanical and Radiopacity Properties of Poly(Methyl Methacrylate)/Barium Titanate-Denture Base Composites
Authors: Elshereksi Nidal W. , Mohamed Saied H. , Arifin Azlan , Ishak Zainal A.M.
Published: September 2018

This study aimed to evaluate the flexural and hardness properties of poly(methyl methacrylate) (PMMA) denture base filled with barium titanate (BaTiO3). The baTiO3 filler was treated with 3-trimethoxysilylpropyl methacrylate, which is a silane coupling agent. Curing was performed in a water bath at 78 °C for 1.5 h. The samples were tested for tensile and flexural strength and surface hardness. The samples were also radiographed, and their optical densities were determined. Radiopacity values were compared with that of an aluminium (Al) plate with equivalent thickness. A reduction in the tensile and flexural strength of the PMMA composite was observed at high filler loadings. However, the surface hardness of the denture base composites was enhanced as a function of filler loading. The radiopacity of the PMMA/BaTiO3 composites was also improved. Adding 10 wt.% of baTiO3 to PMMA resulted in a higher optical density (OD) (p< 0.07) compared with that of Al.
Distarch Phosphate as a Matrix for the Generation of Quantum Dots
Authors: Khachatryan Karen , Khachatryan Gohar , Fiedorowicz Maciej
Published: September 2018

Generation of ZnS, CdS, CaS and MgS quantum dots (QDs) was attempted in the matrix of distarch phosphate, an anionic polysaccharide. Based on the analysis of FTIR spectra, thermograms and Differential Scanning Calorimetry, interactions of QDS with the matrix could be excluded. On generation of MgS QDs and also, to a certain extent, CaS QDs, hydrolysis of the salts generating these QDs took place. That process had an impact on the partial destruction of the matrix. Molecular weight and radii of gyration of the products showed that the generation of QDs was dependent on the properties of the matrix polysaccharide. The elasticity, plasticity and viscosity of the gels containing QDs were significantly lower than those of plain distarch phosphate. Generally these values changed with time similarly to gels free of QDs.
Dental Composites Based on Dimethacrylate Resins Reinforced by Nanoparticulate Silica
Authors: Kleczewska J. , Bieliński D. M. , Nowak J. , Sokołowski J. , Łukomska-Szymańska M.
Published: September 2018

This paper describes morphological differences and associated functional properties of dental composites based on dimethacrylate resins reinforced by nanoparticulate silica filler modified according to different silanization procedures. Surface morphology of the materials was evaluated by means of AFM, while nanohardness and elasticity modulus of the surface layer - by nanoindentation and abrasion - gravimetrically. The effects of silane treatment of nanoparticulate silica surface on possible filler loading, mechanical properties and abrasion resistance of the composites were discussed. The influence of the amount and kind of silane coupling agent on the example of 3 -methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane were presented. The modification of nanoparticulate silica with 3 -methacryloxypropyltrimethoxysilane enabled the introduction of 15% more filler than modification with vinyltrimethoxysilane. The abrasion resistance depended strongly on the composite morphology and the micromechanical parameters of the surface layer. The composite modified with vinyltrimethoxysilane, containing the highest percentage of filler particles smaller than 1 μm in diameter, exhibited the lowest abrasion (0.3 vol.%). Abrasive wear seemed to be a linear function of nanoindentation hardness with the correlation coefficient of R2 = 0.96. The highest hardness of the surface layer of commercial composite (130 MPa) resulted in the highest abrasive wear (7.7 vol.%).

The type and the quantity of silane coupling agent used for silica modification strongly influence the morphology and mechanical and tribological properties of the dental composites. The application of more than the calculated, optimal amount of silane to nanosilica modification enables higher filler loading, but the composites exhibit inferior mechanical characteristics. Nanoindentation hardness of surface layer showed to be the most useful parameter in estimation of material susceptibility to abrasion.
Flame Retardant Properties of Boric Acid and Antimony Oxide Accompanying with Huntite and Hydromagnesite in the Polymer Composites
Authors: Atay Hüsnügül Yılmaz , Çelik Erdal
Published: September 2018

In this study, boric acid and antimony oxide were used as auxiliary flame retardant materials accompanied by huntite and hydromagnesite. To avoid the deteroriation of mechanical properties, a reduced additive amount is required in polymer composites, and it can achieve improved flame resisting properties. The use of finer powders also helps to give better flame retardant properties. Hence, the minerals were utilized to produce polymer nanocomposites to investigate improved flame retardancy with synergetic effects. The ground minerals were added to an epoxy resin with different loading levels and sizes. The composites were characterized by using DTA-TG, FTIR, SEM-EDS and surface profilometry UL94-flame retardancy tests were undertaken as a main objective of this research. The size distribution and mineral type/content effects were measured. It was concluded that the flame retardant properties were improved with increasing mineral content and decreasing size. Boric acid and antimony oxide positively influenced the flame-retardance of flammable polymers when combined with huntite and hydromagnesite.
Viability Study of Use of Reprocessed High Density Polyethylene for Manufacturing Products and Multi Response Optimization of Injection Moulding Parameters Using Grey Relational Analysis
Authors: Gobinath S. , Elangovan D. , Sivakumar E. , Devadasan S.R.
Published: September 2018

In landfill, it was found that the majority of the plastic items are not biodegradable and very gradually degrade. With reprocessed consumer plastics, many attempts have been made to reduce the impact on the environment and to avoid the consumption of virgin plastics. The plastic blend of 50% reprocessed high density polyethylene (HDPE) and 50% virgin HDPE has been used purposely for this study. Usability of reprocessed HDPE as alternative for virgin HDPE is investigated.

This paper investigates the influence of the process parameters melt temperature, holding pressure, and cooling time on tensile strength and flexural strength through Taguchi methodology and grey relational analysis in Injection moulding machine. Multi response characteristics like tensile and flexural strengths are selected to evaluate the process performance and the corresponding moulding parameters of the melt temperature, holding pressure, and cooling time. Optimal combination of injection moulding parameters is determined using Taguchi and Grey relational analysis. Tensile and flexural strengths of the reprocessed HDPE are found close to that of virgin HDPE. Hence, reprocessed HDPE is found a good alternative for virgin HDPE. The confirmation results reveal that, there is significant progress in tensile strength and flexural strength of reprocessed HDPE and Grey relational grade are improved by 6%, 5% and 74% respectively. Optimal combination of the process parameters for the multi-performance characteristics of the reprocessed HDPE is the set with melting temperature at 235 °C, holding pressure at 250 N/m2 and cooling time at 25 s.
Progressive Damage of GFRP Composite Plate under Ballistic Impact: Experimental and Numerical Study
Authors: Ansari Md Muslim , Chakrabarti Anupam
Published: September 2018

In this paper, the behaviour of laminated GFRP composite plate under ballistic impact has been studied with experimental as well as numerical model. Variation of residual velocity, energy absorption, damaged area and modes of damages have been studied. A simplified three dimensional FE model for composite plate and impactor with gap interaction and Lagrangian mesh has been presented. Material characterization of GFRP composite for progressive damage analysis based on material stress/strain failure criteria has been carried out. Shock effect with nonlinear volumetric response of laminated composite during impact is also considered. Pressure wave propagation in composite plate due to impact is also studied. Numerical results from present FE model are validated with those of experimental results showing close agreements in terms of damaged length, energy absorption and variation of residual velocities.
Improving Mechanical Properties of Glass Fibre Reinforced PBT Waste for its Recycling as a Product of Pipe System Elements
Authors: Varga Cs. , Bartha L.
Published: September 2018

PBT [poly(butylene terephthalate)] is an important engineering thermoplastic having several advantageous properties; however, its brittle behaviour is a disadvantage. Blending with a polymer or applying various types of commercial additives are the two methods widely used for taking advantage of PBT while improving its poor impact properties. In our experimental work, different types of commercially available additives have been applied for improving the mechanical properties of glass fibre-reinforced PBT. Blending a cyclic oligomer with GF/PBT samples made them much more elastic, which was shown by better resistance against tensile, flexure, dynamic and cyclic tensile stresses.
A Urethane Block Copolymer as Binder for Fire-Resist Palm-Based Fibreboard
Authors: Redwan Amamer , Badri Khairiah Haji , Baharum Azizah
Published: September 2018

The mechanical properties and fire resistance of medium-density fibreboard (MDF) consisting of empty fruit bunch fibre (EFB) and palm-based pre-polyurethane (pPU) as the green binder were investigated. The EFB was in the size range of 300 to 500 μm with ATH varied at 5, 10, and 15%w/w of the total mass of the resin and was added into the pPU matrix at a ratio of 65:35 of the EFB to pPU. This study discovered the significant of mixing sequence to the strength enhancement of the fibreboard. A direct proportionality was noted between the Shore D hardness and the amount of ATH with an increase up to 17% with increasing ATH content. Furthermore, this is contributed to well-disperse ATH in the pPU matrix which also increased the impact and flexural strengths. An increase in impact strength of 13, 20 and 33%, with increasing ATH loading percentage was observed. The maximum increase in flexural strength was 33%, which was associated to ATH content of 15%. On the other hand, the burning rate decreased from 6.0 to 3.2 mm·s−1 with increasing ATH content.
Preparation of Colloidal Properties and Water Dispersible Conductive Polypyrrole Nanocomposite of Nanocrystalline Cellulose
Authors: Al-Dulaimi Ahmed A. , Wanrosli W.D.
Published: September 2018

The development of conductive polypyrrole (PPY) processability was successfully achieved by a synthesis of colloidal form with high dispersion stability in aqueous medium. In-situ polymerization method of pyrrole monomers (PY) assisted by aqueous suspension nanocrystalline cellulose (NCC) and the oxidizing agent ammonium persulfate (APS). Facial and fast technique consisted of deposition of PY monomers on the NCC surface via electrostatic attractions between the sulfate groups in NCC surface and the amine group of the PY. Steric hindrance feature of NCC suspension significantly influences the colloid production. The nanocomposite of PPY and NCC (PPY-NCC), purified by centrifuge repeatedly and desiccated by freeze-dry technique. The observations of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), clearly shows the nanostructure modification for nanocomposite and the NCC particles after the composition. The PPY-NCC nanocomposite have very good dispersion stability in aqueous media. The variation between PPY and PPY-NCC in the crystallinity and thermal stability was studied by thermogravimetric analysis (TGA) and x-ray diffraction (XRD) respectively.
Effect of Micro- and Nano- Size of Cellulose Particles Extracted from Rice Husk on the Properties of Hydrogels
Authors: Ishak Wan Hafizi Wan , Yin Ooi Shok , Ahmad Ishak
Published: September 2018

The effects of different size of cellulose particles extracted from rice husk on the properties of gelatin/cellulose hydrogels were studied. Micro size cellulose was extracted by alkali and bleaching treatments followed by acid hydrolysis to obtain cellulose nanocrystal (CNC). Both cellulose (micro) and CNC (nano) were used in hydrogels formulation with gelatin (in ratio 25% cellulose dispersion to 75% gelatin). Gelatin was then subjected to chemical cross-linking using glutaraldehyde as crosslinking agent with CNC entrapped in gelatin to produce hydrogels. SEM observation revealed that swollen micro cellulose has irregular and bigger pores compared to cellulose nanocrystal (CNC) hydrogel which has homogeneous and smaller pores arrangement thus affecting their swelling degree. The cellulose fibers exhibit enhanced thermal stability but contrary with the cellulose nanocrystals which showed lower thermal stability.
Documentation and standardization of altered mental status
Authors: Aslaner Mehmet Ali , Baykan Necmi , Doğan Nurettin Özgür , Ziyan Murat
Published: September 2018

Background:

Although altered mental status is a term commonly used for older patients, the limits of the definition are unclear.

Objectives:

We aimed to determine the predictive factors of altered mental status and to standardize this broad-spectrum definition.

Methods:

The level and content of consciousness were assessed both in the basal status and in the emergency department presentation status of patients who were aged 65 years and above. The Richmond Agitation–Sedation Scale (RASS) for level and five features for content of consciousness were used to determine the actual change in consciousness.

Results:

Among 1250 patients, the rate of true altered mental status was 7.7% ( n = 96), transient altered mental status was 3.5% ( n = 44), and non-altered mental status was 88.8% ( n = 1110). The 1- and 3-month mortality rates were higher for patients with true altered mental status (32.3% and 40.6%, respectively) than for other patients (3.3% and 8.4%, respectively; p < .001). The following criteria predicted true altered mental status with a high specificity: a change in RASS score ⩾2 points, newly disorganized thoughts, a perception disorder, inattention and disorientation, and an inability to communicate.

Conclusion:

True altered mental status criteria can be used to determine alterations in consciousness that lead to high mortality, and they can also be used as a common language for current and further investigations.