bluuebunny/crossref_metadata_2025 huggingface dataset:
Agreement profiles for rebound and applanation tonometry in normal and glaucomatous children
Authors: Esmael Amanne , Ismail Yomna M , Elhusseiny Abdelrahman M , Fayed Alaa E , Elhilali Hala M
Published: September 2018

Objectives:

To investigate agreement between intraocular pressure measurements by the rebound tonometer and handheld Perkins applanation tonometer in children with and without primary congenital glaucoma and test agreement with intraocular pressure and age variations.

Materials and methods:

A prospective non-interventional comparative study done on 223 eyes of 115 children, 161 normal eyes, and 62 eyes with primary congenital glaucoma. Intraocular pressure measurements were obtained in the upright position by rebound tonometer first, followed by installation of topical anesthetic eye drops (benoxinate), then measured by Perkins applanation tonometer.

Results:

For all eyes, mean difference between Perkins applanation tonometer and rebound tonometer was −0.59 ± 2.59 mmHg, p = 0.001. Regression analysis with (r) = 0.9, (r2) = 0.79, and p < 0.001. In primary congenital glaucoma: there was a mean difference of −.79 ± 2.82 (p = 0.032), a good correlation with (r) = 0.94, (r2) = 0.87%, and 95% level of agreement: –6.34 to +4.76. In normal eyes: mean difference was −.52 ± 2.5 (p = 0.01), correlation: (r) = 0.8, (r2) = 0.64, and p = 0.001. The 95% level of agreement −5.41 and +4.36 mmHg. In intraocular pressure ⩽ 15 mmHg: mean difference −0.89 ± 2.15 mmHg, 95% level of agreement between −5.1 and +3.32 mmHg, p < 0.001. In intraocular pressure >15 mmHg: mean difference was 0.04 ± 3.28 mmHg, 95% level of agreement −6.38 and +6.46 mmHg, p = 0.914.

Conclusion:

There is a good correlation between rebound tonometer and Perkins applanation tonometer in children with and without primary congenital glaucoma; however, rebound tonometer overestimates the intraocular pressure, and in intraocular pressure >15 mmHg there is less agreement between the two devices. Hence, in higher intraocular pressure measurement caution should be taken when interpreting rebound tonometer readings, and a confirmatory measurement using Perkins applanation tonometer is advised.
Normative posterior pole asymmetry analysis data in healthy Caucasian population
Authors: Altan Cigdem , Arman Berkay Hasan , Arici Murat , Urdem Ufuk , Solmaz Banu , Pasaoglu Isil , Basarir Berna , Onmez Funda , Taskapili Muhittin
Published: September 2018

Purpose:

The aim of this study is to evaluate the variability of central retinal thickness asymmetry in healthy Caucasian adults with the posterior pole asymmetry analysis to serve as a reference.

Methods:

In total, 404 eyes of 202 subjects who aged between 18 and 80 years, who had no ocular pathology, were included in this cross-sectional observational study. Retinal thickness maps with posterior pole asymmetry analysis mode were taken with the optical coherence tomography (SPECTRALIS SD-OCT; Heidelberg Engineering). Superior and inferior hemifields were divided into five zones resembling to the strategy in Glaucoma Hemifield Test. Mean retinal thickness in each of the five zones was compared with the thickness of the corresponding zone in each eye (paired-samples t-test), and differences in retinal thickness (DRT1–5) and ganglion cell layer thickness between reciprocal locations were measured. Differences in retinal thickness values of two eyes of each subject were also compared (independent-samples t-test).

Results:

The intra-eye asymmetry was statistically significant in zones 4 and 5. The highest mean intraocular differences in retinal thickness were 5.8 µm (zone 5) in all eyes, 5.8 µm (zone 5) in the right eyes, and 5.9 µm (zones 4 and 5) in the left eyes. The only statistically significant interocular local differences in retinal thickness asymmetries were found in zone 3. The intraocular asymmetry in retinal thickness was found to be the lowest in zone 1. The differences of ganglion cell layer thickness (GCLTs) were not statistically significant.

Conclusion:

There were statistically significant physiological inter-eye asymmetry in zone 3 and intra-eye asymmetries in zones 4 and 5. These measurements must be considered during screening for glaucoma with posterior pole asymmetry analysis in the Caucasian population.
Seasonal forecasting performance considering varying income elasticities in tourism demand
Authors: Smeral Egon
Published: September 2018

This article analyses varying tourism demand elasticities by season across business cycles based on time series in the context of forecasting performance. We compare for the first time the forecasting performance of models considering the asymmetric behavior of tourism demand with models focusing on symmetric demand behavior. For this reason, this article analyses the outbound expenditures of different source markets by quarter since 2000. The estimation results showed that it was only possible to identify asymmetric income effects. In the case of the price effects, we had to accept—based on the data set available—symmetric behavior. The general outcome of the study revealed compelling evidence that the majority of models allowing us to measure asymmetric income effects yield superior forecasting performance in comparison to models considering only the possibility of symmetric income effects across business cycles.
Dynamic pricing decisions by potential tourists under uncertainty: The effects of tourism advertising
Authors: Song Hongjuan , Jiang Yushi
Published: September 2018

The aim of this study is to examine the advertising information learning processes of potential tourists and observe how potential tourists sequentially adjust their perceived reference prices and purchase intentions with different risk preferences and choices with respect to gains (the current price is lower than the consumer’s reference price) or losses (the current price is higher than the reference price). In this study, a Bayesian experiment was conducted to elicit reference prices in the presence of tourism advertising with uncertain information. The findings show that with respect to gains, risk avoiders do not reduce their reference prices as significantly as do risk seekers when exposed to price-informative advertising. Exposure to image advertising changes potential tourists’ risk preferences, and the reference price drops more significantly for risk avoiders than for risk seekers. With respect to losses, informative and image advertising impact the reference price for participants with different risk preferences but not at a statistically significant level.
Cash regimes and the franchise system: An extension of the marginal value of cash
Authors: Park Kwangmin , Jang SooCheong (Shawn)
Published: September 2018

The main purpose of this study is to examine the marginal value of cash in franchise restaurants by extending Faulkender and Wang’s three cash regimes into the franchise framework. Utilizing theoretical underpinnings from prior studies, this study attempted to verify that franchising is a quasi-debt financing tool for restaurant firms. The sample used in this study was retrieved from Compustat and 10-K annual reports from 1980 to 2015. The results of this study revealed that “raising cash” and “servicing debt” regimes are common in the restaurant industry. This study also found that shareholders place a lower value on the marginal value of cash for franchise restaurants compared with non-franchise restaurants. Furthermore, the market value of additional cash for franchise restaurants decreased when the proportion of franchise sales increased. This study confirmed Norton’s argument that franchising funds are not simply cheap capital. Furthermore, this study found that the value of cash holdings decreased for franchise restaurants based on the level of franchising operations.
Local climate zone classification with different source data in Xi’an, China
Authors: He Shan , Zhang Yunwei , Gu Zhaolin , Su Junwei
Published: September 2018

The city’s local climate zone (LCZ) has been considered as a useful guiding tool for urban climate mapping and classification of urban canopy in cities. However, the LCZ classification methods and results are different in different cities in different countries and regions. Therefore, it is necessary to conduct a targeted research that would take into account local urban morphology and canopy characteristics. In the current work, a LCZ classification method is proposed. This would provide a useful guide for city planning and operation. In the newly proposed method, the LCZ types were first adjusted, according to the characteristics and urban morphology of Chinese cities, in relation to existence of high- and low-rise buildings and high density residential population and land cover of greeneries. Based on investigations of two LCZ classifications of the City of Xi’an, a coupling method was proposed. This method couples the World Urban Database and Access Portal Tools method based on remote sensing data with the classification method based on road network divided by land parcels. The proposed method was validated in this study against the actual land use and construction data that were surveyed in Xi’an, which showed acceptable accuracy. Our results have illustrated the feasibility of our proposed classification for urban LCZ mapping in China.
Can point-of-care testing shorten hospitalization length of stay? An exploratory investigation of infectious agents using regression modelling
Authors: Gkika Eliona , Psaroulaki Anna , Tselentis Yannis , Angelakis Emmanouil , Kouikoglou Vassilis S
Published: September 2018

This retrospective study investigates the potential benefits from the introduction of point-of-care tests for rapid diagnosis of infectious diseases. We analysed a sample of 441 hospitalized patients who had received a final diagnosis related to 18 pathogenic agents. These pathogens were mostly detected by standard tests but were also detectable by point-of-care testing. The length of hospital stay was partitioned into pre- and post-laboratory diagnosis stages. Regression analysis and elementary queueing theory were applied to estimate the impact of quick diagnosis on the mean length of stay and the utilization of healthcare resources. The analysis suggests that eliminating the pre-diagnosis times through point-of-care testing could shorten the mean length of hospital stay for infectious diseases by up to 34 per cent and result in an equal reduction in bed occupancy and other resources. Regression and other more sophisticated models can aid the financing decision-making of pilot point-of-care laboratories in healthcare systems.
Development of a Passenger-Car Radial-Tyre Sidewall Compound by the Reactive Processing of an NR/BR/EPDM Blend in a Banbury Mixer
Authors: Ghosh Soumen , Bhattacharyya Sanjay Kumar , Bandyopadhyay Samar , Dasgupta Saikat , Mukhopadhyay Rabindra
Published: September 2018

In the present study, EPDM (of higher and lower ENB grade) was pretreated inside a Banbury chamber and then mixed with an NR/BR blend in a typical passenger-car radial formulation in order to overcome incompatibility issues arising out of the direct mixing of an NR/BR/EPDM blend. With incorporation of pretreated EPDM in an NR/BR blend, it was possible to reduce antidegradant and wax dosages, with improvement in ozone resistance, fatigue to failure, and cut growth properties.
Effect of Recycled Polypropylene on the Mechanical and Rheological Properties of Polypropylene-NBR Thermoplastic Vulcanisates
Authors: Mamoor G.M. , Irfan Muhammad S. , Gill Yasir Q. , Qaiser Asif A. , Saeed Farhan
Published: September 2018

Virgin polypropylene (PP), recycled polypropylene (RPP) and acrylonitrile butadiene rubber (NBR) were mixed together to prepare ternary blends (PP/RPP/NBR) of thermoplastic vulcanisates (TPVs). The blends comprised 30 parts per hundred (phr) NBR and 70 phr PP and RPP. Sulphur was used to dynamically crosslink the NBR during the blending process. Maleic anhydride grafted polypropylene (MA-g-PP) was used as compatibiliser to enhance the interaction of the polypropylene and the rubber. In this study, the loading of RPP in the TPVs was varied and the effects on mechanical and rheological properties were studied. The hardness and the tensile strength of the TPVs increased upon increasing the RPP loading. The RPP exhibited an adverse effect on elongation-at-break of the vulcanisates, with the pseudo-plastic flow behaviour and the viscosity of the vulcanisates increasing with the increased loading of RPP.
Thermogravimetric and Morphologic Analysis of Oxo-degradable Polyethylene Films after Accelerated Weathering
Authors: Klein Jalma Maria , Ramos Gustavo Roberto , Grisa Ana Maria Coulon , Brandalise Rosmary Nichele , Zeni Mara
Published: September 2018

The degradation of polyethylene films containing a prodegradant additive has been studied after exposure to accelerated weathering for 480 hours. After exposure, the effects of photo-oxidation were evaluated by thermogravimetry, infrared spectroscopy and X-ray diffraction. The kinetics of the thermo-oxidative degradation of polyethylene films, with and without the prodegradant additive, was assessed by applying the Flynn-Wall-Ozawa method to thermogravimetric analysis carried out at different heating rates. The values of activation energy for samples with and without the prodegradant additive were in the range of 166-214 kJ/mol, and increased, after exposure to accelerated weathering, to values in the range of 245-279 kJ/mol. After exposure, the crystallinity index increased by 9 percentage points for the polyethylene sample without the prodegradant additive and by 8 percentage points for the sample containing the prodegradant additive. For both samples exposed to accelerated weathering, an increase in the carbonyl index was observed. The use of the prodegradant additive caused more evident changes in the crystalline regions of the polymer than in the amorphous regions; the results of this study are thus important from the standpoint of degradation, since the crystalline regions are considered difficult to degrade.
Effect of Recycled HDPE with Pro-oxidant on the Photodegradation of HDPE Film
Authors: Samsudin M.S.F , Wahab M.A.A. , Ahamid Z.
Published: September 2018

Stability and photodegradation studies of HDPE film blended with recycled HDPE, with and without pro-oxidant, were carried out by subjecting the film to accelerated UV exposure up to 144 hours. Two types of recycled HDPE were used; one containing pro-oxidant (recycled degradable HDPE – RDH) and the other without pro-oxidant (recycled standard HDPE – RSH). The loading levels of recycled HDPE were varied from 10 to 30% by weight. The degradation behaviour of the film was then evaluated based on elongation at break, carbonyl index and oxidative induction time (OIT). The results obtained show that the degradation rate of HDPE films, with different levels and types of recycled HDPE (RSH and RDH), were directly correlated to UV exposure time. However, more pronounced changes in elongation at break and carbonyl index were observed, in particular the HDPE film blended with RDH. At 30% loading of RDH, the film degraded at a higher rate compared with film containing the same level of RSH. This suggests that HDPE blended with RDH even at a low loading of 10% could promote degradation of the film. The remaining pro-oxidants in RDH induced the formation of free radicals in the HDPE chain and accelerated the degradation process.
Comparison Effect of Mica and Talc as Filler in EPDM Composites on Curing, Tensile and Thermal Properties
Authors: Ismail H. , Ishak S. , Hamid Z.A.A.
Published: September 2018

In this work, the comparison effect of mica and talc as filler in EPDM composites on curing, tensile, thermal properties was studied. EPDM/mineral fillers composites were compounded using two roll mill at various filler loading (i.e., 100/0, 100/10, 100/15, 100/30, 100/50, 100/70) and curing characteristics were carried out at 160°C using a Monsanto Moving Die Rheometer. The tensile and thermal properties as well as fracture surfaces of composites were tested using Instron Universal Testing Machine, Thermal Gravimetric Analysis (TGA) and Emission Scanning Electron Microscope (SEM). The results indicated that the optimum cure time (t90), scorch time (ts2) decreased, while maximum torque (MH) increased for both composites with increasing filler loading. The tensile properties of EPDM/mica and EPDM/talc composites increased with increasing filler loading and the optimum tensile strength and tensile modulus for both mineral fillers occurred at 50 phr. EPDM/mica composites showed better tensile properties due to strong interfacial interaction between filler and matrix than EPDM/talc composites. In addition, thermal stability of both composites improved with increasing filler loading.
Development of a Rubber-Based Product Using a Mixture Experiment: A Challenging Case Study
Authors: Kaya Yahya , Piepel Greg F. , Caniyilmaz Erdal
Published: September 2018

Many products used in daily life are made by blending two or more components. The properties of such products typically depend on the relative proportions of the components. Experimental design, modeling, and data analysis methods for mixture experiments provide for efficiently determining the component proportions that will yield a product with desired properties. This article presents a case study of the work performed to develop a new rubber formulation for an o-ring (a circular gasket) with requirements specified on 10 product properties. Each step of the study is discussed, including: 1) identifying the objective of the study and requirements for properties of the o-ring, 2) selecting the components to vary and specifying the component constraints, 3) constructing a mixture experiment design, 4) measuring the responses and assessing the data, 5) developing property-composition models, 6) selecting the new product formulation, and 7) confirming the selected formulation in manufacturing. The case study includes some challenging and new aspects, which are discussed in the article.
Effect of Fly Ash as Filler in Rubber – A Comprehensive Study of the Vulcanisate Properties of Styrene-Butadiene Rubber Compounds
Authors: Dasgupta Mridul , Kar Saptarshi , Gupta Saikat Das , Mukhopadhyay Rabindra , Bandyopadhyay Abhijit
Published: September 2018

The effect of fly ash as a filler for an ESBR-based compound was studied in the range 0-80 phr. Characterization of fly ash, as received, revealed the abundance of 200 mesh size particles with an average diameter of 10 μm; composition analysis showed the predominance of silica and alumina.

The properties of ESBR compounds filled with fly ash particles of ≤200 mesh were compared with those of clay- and whiting-filled compounds. The cure rate index remained unchanged for fly ash throughout the range of loading studied here; clay showed a lower cure rate, and whiting showed a higher value than fly ash. The 300% modulus values did not show any improvement with increase in fly ash loading, the values being comparable with those for whiting and inferior to those for clay. Fly ash gives the lowest heat build-up and tan delta (at 70°C) values among the three fillers under discussion.
Controllable Microwave-Assisted Polycarbonate Waste Chemical Recycling
Authors: Nikje Mir Mohammad Alavi , Askarzadeh Mohammad
Published: September 2018

A simple, convenient and novel method was developed for the recovery of bisphenol-A from polycarbonate wastes under microwave irradiation. In this study bisphenol-A was recovered at a 100% yield by using a mixture of glycerol/water as the green solvent and sodium hydroxide as the catalyst, respectively. This methodology can overcome the disadvantages existing in traditional methods such as long reaction times, high energy consumptions, use of harmful reagents and environmental problems, and is applicable to all types of polycarbonates.
Mechanical Properties of the Composite Material Based on Modified Scrap Tires and Polymer Binder
Authors: Plesuma R. , Megne A. , Mateusa-Krukle I. , Malers L.
Published: September 2018

The present work focuses on the investigation of the mechanical properties of the composite material composed of preliminary modified rubber crumb and a polymer binder. The modification of rubber crumb was realized by means of treatment with water or sulphuric acid, in order to change the degree of polymer crosslinking or to intensify adhesion interaction between rubber particles and polymer binder. The Shore C hardness, compressive stress at 10% deformation and compression modulus of elasticity, ultimate tensile strength and elongation at break of composite material, in correlation with its composition and adhesion between rubber and polymer binder were investigated.

Obtained results show possibility of attaining significant changes in the mechanical properties of composite material by selected rubber crumb treatment methods, in correlation with the composite material composition. This gives additional opportunity for meaningful improvement of composite material production technology.
Rheological Behaviour of Recycled and Virgin Polyethyleneterephthalate and Mixtures of Them
Authors: Kostov George , Atanassov Atanas , Kiryakova Dimitrina
Published: September 2018

Different blends of virgin, recycled polyethyleneterephthalate (5-20 mass %) and their mixtures used for textile fibers were prepared. Their rheological characteristics were studied at temperatures 543, 548 and 553 K and shear stresses in the range from 6.2×103 to 14×103 Pa. Drawing the flow curves for the melts of the polymers studied using experimental data, it was found that they obeyed the power law at the three temperatures. A weak tendency of increase of the flow index was observed with the increase of temperature. The effects of two different stabilizers (Irganox 1076 and butylated hydroxytoluene BHT, 0.5 mass% vs. the polymer material) on the thermooxidative degradation were studied. The stabilizing ability of Irganox 1076 was found to be the better one since it increased viscosity from 50 to 100 Pa.s without any significant changes in polyethyleneterephthalate appearance. The influence of processing reiteration was studied for the individual polymers, as well as for their mixtures in different ratios.
Bonding Characteristics of Macro Polypropylene (Pp) Fibre in Pva/Macro Pp Blended Fibre-Reinforced Styrene Butadiene Latex-Modified Cement-Based Composites
Authors: Kim Dong-Hyun , Lee Seung-Kee , Park Chan-Gi
Published: September 2018

The bonding properties of macro polypropylene (PP) fibres in blended fibre-reinforced polymer-modified cement-based composites (BFRPMCCs) containing styrene butadiene (SB) latex were evaluated. A blend of polyvinyl alcohol (PVA) and macro PP fibres was used in the study. The pullout behaviour was investigated using dog-bone test specimens compliant with JCI SF-8. The macro PP fibre was added at 0.45 kg/m3 and the PVA fibre was added at 12.6 kg/m3 to fabricate the BFRPMCCs, and SB latex was added at 0–25 wt% of the cement. The addition of SB latex improved the dispersion of the PVA fibres, increased the pullout resistance of the macro PP fibre embedded in the BFRPMCC, and induced strain hardening in the debonded zone. The maximum bond strength occurred at an SB latex content of 10%, and the maximum interface toughness occurred at an SB latex content of 15%. Microstructural analysis of the macro PP fibre surfaces was carried out following pullout of the fibres embedded in the SB-latex-containing BFRPMCC. The amount of scratches increased with increasing SB latex content until 15%, but then decreased at SB latex contents above 20%, indicating that the bonding of the composite was optimum at a latex content of 15%.
Evaluation of Recycled Polymers from Crt Monitor Frames of Different Years of Manufacture
Authors: Gabriel Adjanara P. , Santana Ruth M. C. , Veit Hugo M.
Published: September 2018

The recycling of polymeric waste has attracted considerable interest and many efforts have been made to facilitate large scale recycling. The rapid evolution of technology has generated large volumes of obsolete and unusable polymeric products. One example is the CRT (cathode ray tubes) monitor that are rapidly being replaced by monitor types such as LCD, LED and Plasma. The present materials and routes for recycling this waste is not well known, which encourages studies in this area. The main objective of this work is to identify the type of polymer present in the CRT monitor frames and evaluate if the quality of the recycled polymer is changed according to the monitor age (year of manufacture). Monitors of different years of manufacture but the same brand were collected and disassembled. Frames were separated into two groups (older and younger). After, the frames were comminuted and samples were injected, according to ASTM D638-08. The samples were characterized by infrared, density, mechanical, MEV and TGA tests. The results obtained by infrared (FTIR) showed that regardless of the year of manufacture the monitor frames are produced with the same polymeric material, which was identified as copolymer ABS (acrylonitrile butadiene styrene). The results of mechanical and thermal tests showed that, in general, the recycled ABS polymers regardless of the year of manufacture showed no significant losses in their properties. However, it was found, by the TGA test, that there was a small variation in polymer composition.
Pyrolysis, Kinetic and Kinetic Model Study of Epoxidized Natural Rubber
Authors: Alwaan I.M. , Hassan A.
Published: September 2018

Pyrolysis, kinetics properties and a kinetic model of epoxidized natural rubber (ENR-50) were studied in this work by differential scanning calorimeter (DSC) and thermogravimetry analysis (TGA/DTGA) tests. DSC results indicated that the ENR-50 rubber remained still, without degradation, until 354.65°C and ENR-50 degrades at temperatures ranging between 354.65 to 420°C at a constant heat rate (10°C/min). The degradation enthalpy was (-1241.8 J/g) and the remaining ash was 1.48% at 500°C. Degradation kinetics were studied according to Kissinger, Flynn-Wall-Ozawa, Friedman and Kissinger-Akahira-Sunose methods at different heating rates in nitrogen, at a flow rate of 20 ml/min. Activation energies and the pre-exponential factor were evaluated from the slope of Flynn-Wall-Ozawa, Friedman and Kissinger-Akahira-Sunose plots at conversions between 10 and 90%. The activation energy was also calculated by the Kissinger's method and it was equal to 41.735 kJ mol−1. Criado's method was employed to investigate the kinetic model, g(α) of ENR-50 and it was found that the diffusion model (D1) agreed with ENR-50 degradation data.
From Thermosetting to Thermoplastic: A Novel One-Pot Approach to Recycle Polyurethane Wastes via Reactive Compounding with Diethanolamine
Authors: Wang Mengya , Zhang Xinxing , Zhang Wei , Lu Canhui , Yuan Guiping
Published: September 2018

The aim of this study is to develop a one-pot and environmentally friendly approach to recycle polyurethane foams (PUF) via reactive compounding with diethanolamine (DEA) in a melt-mixer. DEA was used as a decomposing agent to destroy the crosslink structure of PUF. The degraded products which have low molecular weight can be used as a plasticizer without any purification to improve molecular mobility of polyurethane. As a result, the thermosetting PUF was converted to thermoplastic regenerated polyurethanes (RPU). This method showed great improvement in cost efficiency comparing to other frequently used reclaiming method of PUF. The structural development of PUF during reactive compounding was investigated in detail. The results indicated that the gel content of PUF decreased significantly from its original 19.6% to 2.3% after reactive compounding with 0.5 phr DEA, demonstrating the decrosslinking of PUF. The prepared RPU showed excellent mechanical properties with the tensile strength of 13.7 MPa and elongation at break of 158.9%. This facile and low-cost reactive compounding approach is suitable for large-scale application and is expected to achieve value-added utilization of PU wastes.
Tensile and Dynamic Mechanical Properties of Natural Rubber and Polyurethane Composites Filled with Cobalt Ferrite
Authors: Hunyek Anuchit , Sirisathitkul Chitnarong , Harding Pimphaka
Published: September 2018

Incorporation of magnetic powders into polymers gives rise to electromagnetic properties useful in sensors and electromagnetic wave absorbers. However, such advantageous properties are introduced in polymer composites at the expense of some mechanical properties. This work aims to explore the effects of magnetic cobalt ferrite (CoFe2O4) fillers on the tensile and dynamic mechanical properties of natural rubber (NR) and polyurethane (PU) matrices from 0 to 45 phr prepared using a 2-roll mill. The tensile properties deteriorated in the case of NR whereas the storage modulus was reduced for PU composites. The CoFe2O4 inhibited the crosslinking and orientations to form crystallites in NR and reduced the stiffness of PU due to poor adsorption between the matrix and fillers. One effect in common was the reduced damping coefficient in both NR and PU composites by the incorporation of CoFe2O4.
Solvent Transport Properties of Er/Ps Thermoplastic Elastomeric Blends
Authors: Vijayakumar PC , Jeevan Kumar R. , Johns Anish , Sathyan N , Johns Jobish
Published: September 2018

Novel thermoplastic elastomeric blends from Polystyrene (PS) and Exudated Resin (ER) of Ailanthus Malabaricum tree are prepared by solution casting technique. The applicability of the resulting materials to design and fabricate barrier rubber materials for the transport and storage of liquids and gases has been studied in terms of solvent resistivity. It is important to carry out the transport studies to eliminate diffusion of chemicals into such material products. The sorption and diffusion of benzene through blends of Polystyrene and Exudated Resin of different compositions are studied at 35°C, 55°C and 65°C. The effects of blend ratio on diffusion, sorption and permeation coefficients are determined. The sorption data is used to estimate the activation energies of diffusion and permeation parameters. An anomalous behavior is observed for most of the blend compositions. The blend with 60/40 PS/ER combination at 35°C and 65°C exhibited Fickian transport mechanism. Minimum solvent uptake is observed for the blend ratio 60/40 PS/ER. This blend ratio shows better compatibility between the phases among the series of the blends studied.
Significance of Technological Parameters for Selected Mechanical Properties of Composite Material Based on Scrap Tires
Authors: Plesuma R. , Malers L.
Published: September 2018

The present work is to be considered as additional research to the authors' previous studies. It is dedicated to the specification of the significance and impact of certain selected technological parameters on mechanical properties of the composite material based on scrap tires. The special method what is known as the “Greece-Latin square” was applied to estimate significance of each technological parameter (input parameter) for selected properties (output parameters) of the material.

Moulding pressure (P), formation time (x), polymer binder content (Cpol.) and the size of rubber particles (R) were selected as the input parameters. Compressive modulus of elasticity (Ec), compressive stress at 10% deformation (σ10%), permanent deformation after 10% deformation in compressive mode (ε) and apparent density (AD) were chosen as the output parameters. An analysis of the obtained dispersion diagrams confirms that composition of the composite material (polymer content) has a greater impact on selected mechanical properties of the material than any other technological input parameter, but apparent density of the composite material demonstrates higher sensitivity to the formation time and moulding pressure of the material than to other input parameters.

The obtained results of the experiment enable further optimization of the composite material production technology and at the same time securing the predictable mechanical properties of the material.
Research on the Application Properties of Tpe/Ommt as Mold Materials
Authors: Junhua Wang , Jiaming Wu , Yuqi Liu , Jincheng Wang
Published: September 2018

The aim of this work was to select one type of polymer as an alternative to room-temperature-vulcanizated silicone rubber (RTV) which was used in the preparation of rubber molds.

Thermoplastic elastomer (TPE) and its organo-montmorillonite (OMMT) filled composites were chosen as candidates. Their structure and properties were researched and compared. The properties such as tensile strength, elongation at break, dimensional stability, and thermal stability were studied. The composite with 1 wt% OMMT showed the highest tensile strength and elongation at break, 10.9 MPa and 1313.6%, which was 172.5% and 30.3% higher than that of pure RTV. In addition, this TPE composite exhibited excellent thermal and dimensional stability. At room temperature, the coefficient of linear expansion (COLE) and coefficient of volume expansion (COVE) of the TPE/OMMT-1 wt% was 2.3×10−5 and 7.2×10−4, respectively. This was 87% and 86% lower compared to that of pure RTV, 1.7×10−4 and 5.1×10−3. This dimensional stability was superior to the pure RTV, indicating this composite can be used as an alternative to RTV as mold material to improve the texture fineness of the culture stone. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used in the investigation of the microtopography of the TPE composites. It was revealed that the layered silicates exhibited partial exfoliation with the addition of 1 wt% OMMT in the matrix.
Evaluation of Fluorosilicone – Silicone Elastomer Blend for Aeronautical Fuel System
Authors: Bhuvaneswari C.M. , Dhanasekaran R. , Chakravarthy S.K.R. , Kale Shirish S. , Gouda Gantayata
Published: September 2018

Elastomer blends based on fluorosilicone and silicone rubber have been investigated as a seal for aeronautical fuel system. Fluorosilicone seals are widely used as a prospective candidate in the aeronautical fuel system due to its notable resistance to aircraft turbine fuel (ATF) as well as its service in wide temperature applications. However, the FVMQ is relatively inferior in strength and high in cost compared to other ATF resistant elastomers. The drawbacks of FVMQ can be improved by blending with a High Consistent Rubber (HCR) such as vinyl methyl silicone (VMQ), which enhances the strength and reduces the cost. In the present work, an attempt has been made to study the properties and optimization of FVMQ-VMQ blend ratio by varying VMQ content. Blends were prepared in two-roll rubber mixing mill, cured and characterized for rheological, mechanical, physical, ageing and low temperature brittleness resistance. Furthermore, the effects of various aeronautical fluids such as ATF, lubricating and hydraulic oil on blends were also analysed. This paper reports the preface analysis of the properties of FVMQ-VMQ blend as a futuristic seal for the aeronautical fuel system.
The Rheological Properties of Trinidad Asphaltic Materials Blended with Waste Cooking Oil
Authors: Maharaj Rean , Harry Vitra , Mohamed Nazim
Published: September 2018

This paper investigates the influence of Waste Cooking Oil (WCO) on the rheological properties of three Trinidad asphaltic base binders: Trinidad Lake Asphalt (TLA), Trinidad Petroleum Bitumen (TPB) and a TLA:TPB (50:50) mixture. The addition of WCO to the asphaltic base binders resulted in changes in the rheological properties as demonstrated by changes in the phase angle, δ (elasticity) and the complex modulus, G* (stiffness) of the blends. The intricate relationship between the chemical composition of the binder and the influence of the WCO was evident as changes in δ and G* due to the addition of WCO was not generalized and were different for each of the asphaltic base binder. The incremental addition of WCO into the three asphaltic binders resulted in the softening of the material (decrease in the G*). Incremental addition of WCO into the TLA asphaltic binder resulted in an incremental decrease in elasticity (maximum δ at 6% WCO), however minimum values of δ were observed (highest elasticity) at 8% WCO for TPB and at 2% WCO for the TLA:TPB (50:50) base blend, the latter blend being the most elastic with a phase angle (δ) of 20.5 degrees. This value of 20.5 degrees was far lower than that of TLA (73%) under identical testing conditions. In all cases G” > G' indicating viscoelastic liquid behavior for the base asphalts and its blends. The study demonstrated the capability to create customized asphalt-WCO blends to suit special applications by formulating specific quantities of Trinidad base asphalts and WCO thus offering an environmentally attractive option for improving the use of asphalt.
Crumb Tire Rubber Polyolefin Elastomer Modified Asphalt with Hot Storage Stability
Authors: Wang Shifeng , Xie Yuge
Published: September 2018

Compared to styrene-butadiene-styrene copolymer (SBS) as the most used asphalt modifier, polyolefin elastomer (POE) has not been used because of the phase separation during hot storage. The structure and property of POE and POE/crumb tire rubber (CTR) blends modified asphalts were studied by optical microscopy, rheological measurements and aging resistance, respectively. POE particles dispersed irregularly in the bituminous phase below 4 wt% POE, and a continuous POE phase formed over 6 wt%. The screw extrusion and the content of the compatibilizer significantly affected the hot storage stability of the POE/CTR blends modified asphalts. The CTR and POE mutually stabilized in the asphalt by screw extrusion in the presence of glycidylmethacrylate functionalized polymer. The extruded POE/CTR dispersed more finely in the asphalt than controlled POE. The stabilized POE/CTR modified asphalt had better aging resistance than regular SBS modified asphalt.
The Potential Use of Natural Rubber in Pharmaceutical Closures
Authors: Bich Nguyen Ngoc , Trang Nguyen Thi Hue , Luan Nguyen Duy , Van Son Huynh
Published: September 2018

Current manufacturing techniques could produce natural rubber closures that meet all criteria standardized by pharmacopeias except the ultraviolet absorbance limit in the range of 220–360 nm for the closures’ leachate. The type and the dosage of the rubber compounds’ ingredients affected the ultraviolet absorbance of the leachate, while rinsing the closures in water with ultrasonic waves and ozone did not. Intensive washing of the rubber coagulum and deproteinization of the rubber latex using bromelain reduced ultraviolet absorbance of the leachate significantly. Further purification of natural rubber latex is necessary to enable the use of natural rubber in pharmaceutical closures.
Properties of Recycled PS/SBR Blends: Effect of SBR Pretreatment
Authors: Veilleux Justine , Rodrigue Denis
Published: September 2018

The properties of recycled styrene-butadiene rubber (SBR) blended with virgin polystyrene (PS) have been investigated over a wide range of concentrations (0–94% wt. SBR). The compounds were prepared by twin-screw extrusion followed by injection molding. A pre-treatment in solution (toluene) was also performed to improve the compatibility between the phases. Extraction tests and thermogravimetry were used to determine the amount of PS inserted in the SBR particles. Morphological analysis (SEM) coupled with physical (density and hardness) and mechanical (tension, flexion, torsion and impact) measurements were performed to assess the final behavior of the mixtures. The results show that the proposed treatment can improve the properties, especially at SBR concentrations greater than 50% wt.
Process Analysis of Controllable Polycarbonate Depolymerization in Ethylene Glycol
Authors: Li Baixue , Xue Feng , Wang Jian , Ding Enyong , Li Zhen
Published: September 2018

A simple and convenient method was explored for glycolyzing polycarbonate (PC). Different from the harsh conditions in traditional methods, this method can be performed under moderate condition by using 1, 4-dioxane as the solvent and zinc acetate as the catalyst. The recycling of PC has been extensively studied for the recovery of bisphenol-A, whereas in this study, the controllable glycolysis of PC could be achieved at various reaction conditions. The glycolysis products with different molecular weight can be used to copolymerize with other monomers to prepare copolymers. This simple chemical technology will certainly facilitate the cyclic utilization of PC.
Preparation and Characterization of Novel Acrylic Polymer Latex Using Novel Emulsifiers
Authors: Xu Tingting , Bao Zhongbin , Zhang Cuifeng , Chen Lijun
Published: September 2018

The acrylic polymer latex was prepared successfully via semi-continuous seeded emulsion polymerization of methyl methacrylate(MMA), butyl acrylate(BA) and functional monomer butanedioicacid, 2-methylene-, 4-butylester (MBI) in water phase when mixed surfactants of tetradecyl dimethyl hydroxy propyl betaine and polyethylene glocolmono-nonylphenylether(OP-10) and 2,2′-azobis (2-methyl propion- amidine)dihydrochloride(V-50) were used to be emulsifier and initiator, respectively. The structure of the resultant latex is detected by Fourier transform infrared spectroscopy spectrum (FTIR) and differential scanning calorimetry (DSC) also confirmed that latex is a kind of random copolymer. Factors, which have an effect on the emulsion polymerization and properties of the resultant latex, have been optimized. Results show that optimum conditions for preparing the latex is as follows: the amount of emulsifier, V-50 and MBI are 7%, 0.5% and 4%, respectively.
Plastic Waste Particles in Mortar Composites: Sulfate Resistance and Thermal Coefficients
Authors: Benosman A. S. , Taïbi H. , Senhadji Y. , Mouli M. , Belbachir M. , Bahlouli M.I.
Published: September 2018

Plastic industry produces large amounts of waste polyethylene terephthalate (WPET), what causes environmental problems. An investigation was carried out on the effect of sulfate attack on the durability of composites produced with WPET. An attempt was also made to determine the thermal coefficients as well as the dynamic elastic moduli. Experiments were accomplished on limestone sand and cement mortars where the blended Portland cement was partially replaced by various volume fractions of WPET particles. The test solutions used to supply the sulfate ions and cations were 5% sodium sulfate solution and 5% magnesium sulfate solution. Tap water was used as the reference solution. Mass changes, compressive and flexion strengths measured on specimens were used to assess the changes in the mechanical properties of composites exposed to sulfate attack at different times. X-ray diffraction, FT-IR spectroscopy, scanning electron microscope (SEM/EDS) and differential scanning calorimetry were used to evaluate the microstructural nature of the sulfate attack. The test results showed that the presence of WPET had a beneficial effect in the control of the strength loss due to sodium and magnesium sulfate attacks and gave better insulation properties. This study insures that reusing TWPET particles as cement substitutes in mortar gives a good approach to sulfate durability, insulation, mechanical properties and solves some of the solid waste problems posed by plastics. Therefore, WPET-mortar composites are often presented as the materials of the future because of their potential for innovation and the advantages they offer. In fact, using WPETs as cement substitutes reduces the energy consumption. These composites address problems related to environmental pollution by CO2 emissions, and are used to repair various reinforced concrete structures.
Effects of Sweat and 3D-deformation on the Mechanical Behaviour of Nitrile Rubber Gloves
Authors: Vinches Ludwig , Zemzem Mohamed , Hallé Stéphane
Published: September 2018

Research has proven that mechanical deformations (MD) caused by hand flexing affect the structure of disposable protective gloves. However, these studies do not consider the presence of a physiological solution such as sweat. The combination of mechanical constraints and sweat might modify the mechanical and physical properties of the protective gloves and therefor their effectiveness. The main objective of this work is to evaluate the combined effects of human sweat and MDs on certain physical and mechanical phenomena that could affect the structure of nitrile rubber protective gloves. The strain energy, crystallinity, swelling and glove surface profile were investigated. Combined with MDs, the physiological solution significantly affects the structure of the gloves. Contact of the glove sample with the physiological solution modified the strain energy and induced a swelling that modified mechanical properties. Also, the deformation frequency greatly affected the strain energy and the number of deformations changed the degree of crystallinity. A qualitative analysis by SEM showed the deterioration of the surface of the gloves in contact with skin. Based on these results, further investigation is needed on the overall effect of sweat on the effectiveness of protective gloves against mechanical and chemical hazards.
Characterization of the Viscoelastic and Vulcanization Behavior of Natural Rubber Nanocomposites Having Different Levels of Nano Silicate/Black
Authors: Mohammadian-Gezaz Somayyeh , Karrabi Mohammad
Published: September 2018

The effects of various loadings of nano layered silicate (NS) and black (BK) were investigated on the cure and stress relaxation behavior of natural rubber (NR), for both uncured and cured states. The changes in elastic (S′) and viscous (S″) vulcanization torques were meaningfully different. The drop in S″max (DS″) was larger for NS than BK; and lowered when the amounts of reinforcements increased. As the nano particles concentration increased, peak of S″ happened in shorter time and higher conversion of cure. Relaxation curves were divided into two viscous and elastic regions at short and long times. With increasing nano filler content, elastic (Ae) and viscous (Av) slopes of relaxation increased. Av was bigger than Ae for uncured compounds while after cure the reverse trend was observed. Vulcanized samples had higher Ae, which clearly confirmed different viscoelastic behavior caused by curing. Comparing with BK, NS had more significant effect on the rate of falling of the relaxation modulus, especially after curing.

The ratio of drop in relaxation modulus in the viscous zone to the elastic zone (ΔGv/ΔGe) decreased as a function of NS/BK content for uncured samples; and increased with NS and BK level after cure. In both cured and uncured samples, NS was more effective on ΔGv/ΔGe than BK. An interesting correlation was found between viscoelastic parameters obtained from cure and stress relaxation studies.
Effect of Cyclo-Olefin Copolymer Loading on Kinetics, Thermodynamics and Model of Linear Low Density Polyethylene Crystallinity
Authors: Alwaan I.M.
Published: September 2018

The behavior of kinetic and thermodynamic characteristics of linear low-density polyethylene (LLDPE) crystallinity containing cyclo-olefin copolymer (COC) were investigated by means of differential scanning calorimeter (DSC). The crystallinity kinetic parameters including the crystallinity apparent activation energy (E), rate of crystallinity constant (K) and the order of crystallinity (n) were calculated with Borchardt and Daniels methods. The results have shown that the activation energy of blends increased with increase in the COC loading and the order of crystallinity was the first order for all blends. Gibbs free energy, enthalpy and entropy of the LLDPE crystallinity increased with the loading of COC. The different crystallinity kinetic models of LLDPE were observed with the loading of COC. It was concluded that the COC hindered the chains of polymer from aligning in a row.