bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavior of Chinese Dahurian Larch Wood after High‐Temperature Exposure: Degradation of Mechanical Properties and Damage Constitutive Model
Authors: Xie Qifang , Zhang Lipeng , Yang Zhenglei , Wang Long , Wu Yaopeng
Published: September 2018

Wood has been extensively used in Chinese ancient buildings, and it is important to clearly understand the mechanical properties of wood after exposure to elevated temperatures. In this paper, three kinds of tests with 102 clear wood specimens fabricated with Chinese Dahurian larch for each kind of test were conducted. The residual compressive strength, tensile strength, and shear strength parallel to grain of specimens after exposure to different temperatures (100°C, 150°C, 200°C, and 250°C) with various exposure times (15 min, 30 min, and 45 min) and different cooling methods (natural cooling and water cooling) were obtained. Results indicate that exposure to elevated temperatures causes great degradation of compressive strength, tensile strength, and shear strength parallel to grain. When the exposure temperatures exceed 200°C, the relative compressive strength, tensile strength, and shear strength parallel to grain decrease greatly with the increase of exposure time. The residual compressive strength, tensile strength, and shear strength of specimens after water cooling are lower than that after natural cooling. Exposure temperatures also have a great impact on the weight loss and color change of wood. Based on the test data, degradation models for the residual compressive strength, tensile strength, and shear strength of wood were developed. Furthermore, the damage constitutive model of compressive (CDMC) and tensile (CDMT) parallel to grain was established and validated reasonably by tests.
In Vitro and In Vivo Inhibitory Effect of Gujin Xiaoliu Tang in Non‐Small Cell Lung Cancer
Authors: Hou Chao , Zhou Dai-Han , Wu Yong-Jian , Dai Xiao-Jun , Wang Qing-Ying , Wu Yin-Qiu , Zhang En-Xin
Published: September 2018

Non‐small cell lung cancer (NSCLC) is a serious threat to people’s health. This study aims to determine the possible effect of Gujin Xiaoliu Tang (GJXLT) on NSCLC, which is an empirical formula from Professor Dai‐Han Zhou. In this study, chromatographic fingerprinting of GJXLT and A549 cell model in vitro and in vivo was established. We cultured A549 cells in vitro and found that GJXLT inhibited A549 cell growth and induced apoptosis. Compared with the control group, the expression of p‐STAT3 and VEGF proteins in the GJXLT groups was decreased. Similar findings were also observed in vivo. First, GJXLT inhibited the growth of transplanted tumor and did not reduce the weight of the tumor‐bearing mice in comparison with that of the control group. Then, the Ki‐67 expression of transplanted tumor in the GJXLT groups was decreased. In addition, the apoptosis rate of transplanted tumor in the GJXLT groups was increased. Overall, our data showed that GJXLT inhibited A549 cell proliferation and induced apoptosis in vivo and in vitro. Furthermore, GJXLT inhibited the growth of lung cancer xenograft in nude mice model with no obvious side effects. The anti‐tumor effect of GJXLT might also be related to the inhibition of p‐STATS and VEGF expression in the JAK2/STAT3 pathway. Our results demonstrated the potential of GJXLT as a novel treatment for NSCLC.
Myeloid Sarcoma of Orbits: Effectiveness of a Low-Dose Radiation Regimen
Authors: Ravisankar Shyam , Levy Yair , Shah Maya
Published: September 2018

Acute myeloid leukemia (AML) can present with extramedullary involvement known as myeloid sarcoma (MS). We present the case of a young woman who was diagnosed with AML and MS in bilateral orbits, brain, omentum, and retroperitoneum. She was treated with induction chemotherapy. Low-dose radiation was given to the orbits due to visual symptoms which resulted in complete response. The use of radiation therapy in orbital MS has not been studied extensively, and low dose may be adequate to achieve complete remission (CR) in selected patients.
The TLR7/8/9 Antagonist IMO-8503 Inhibits Cancer-Induced Cachexia
Authors: Calore Federica , Londhe Priya , Fadda Paolo , Nigita Giovanni , Casadei Lucia , Marceca Gioacchino Paolo , Fassan Matteo , Lovat Francesca , Gasparini Pierluigi , Rizzotto Lara , Zanesi Nicola , Jackson Devine , Mehta Svasti , Nana-Sinkam Patrick , Sampath Deepa , Pollock Raphael E. , Guttridge Denis C. , Croce Carlo M.
Published: September 2018

Muscle wasting is a feature of the cachexia syndrome, which contributes significantly to the mortality of patients with cancer. We have previously demonstrated that miR-21 is secreted through extracellular vesicles (EV) by lung and pancreatic cancer cells and promotes JNK-dependent cell death through its binding to the TLR7 receptor in murine myoblasts. Here, we evaluate the ability of IMO-8503, a TLR7, 8, and 9 antagonist, to inhibit cancer-induced cachexia. Using EVs isolated from lung and pancreatic cancer cells and from patient plasma samples, we demonstrate that IMO-8503 inhibits cell death induced by circulating miRNAs with no significant toxicity. Intraperitoneal administration of the antagonist in a murine model for Lewis lung carcinoma (LLC-induced cachexia) strongly impaired several cachexia-related features, such as the expression of Pax7 as well as caspase-3 and PARP cleavage in skeletal muscles, and significantly prevented the loss of lean mass in tumor-bearing mice. IMO-8503 also impaired circulating miRNA–induced cell death in human primary myoblasts. Taken together, our findings strongly indicate that IMO-8503 serves as a potential therapy for the treatment of cancer cachexia.

Significance:

Cancer-associated cachexia is a significant problem for patients with cancer that remain poorly understood, understudied, and inadequately treated; these findings report a potential new therapeutic for the treatment of TLR7-mediated cancer cachexia.
Two Faces of a Cathedral: Ákos Rózmann’s Black Illusions and Organ Piece No. III/a
Authors: Loch Gergely
Published: September 2018

After composer and organist Ákos Rózmann (1939–2005) moved from his native Hungary to Sweden in 1971, it became his conviction that instrumental composition had no future, and he committed himself completely to the electroacoustic studio. An important part of Rózmann’s self-characterization and the early reception of his music was the statement that his electroacoustic compositions were the results of working as a spiritual medium. While the author demonstrates the relevance of this statement, he also challenges it by presenting an exception, Black Illusions (2003), Rózmann’s only work admittedly created as a sounding autobiography. He also presents Rózmann’s last finished composition, Organ Piece No. III/a—a “dizygotic twin brother” of Black Illusions—and the differing ways in which the two pieces are related to St. Eric’s Cathedral of Stockholm. One of them thematizes the church as a place of personal earthly suffering, while the other presents it as a symbolic stage of otherworldly processes.
Sound Technologies as Agency-Granting Prosthesis to Vocal Body
Authors: Warren Kristina
Published: September 2018

Western voice is historically de-agentialized, that is, gendered female, opposed to performer self-listening, de-privileged relative to composition and rendered ocularcentric by recording technologies. However, by employing sound technologies as prosthesis to the vocal body, and by self-listening to manage the body-prosthesis relationship, contemporary extended voice practitioners figure as cyborgs reclaiming vocal agency, that is, input into mediation of and by one’s technologized vocal body.
Inward Foreign Direct Investment and U.S. Public Opinion on Immigration
Authors: Lee Hak‐Seon
Published: September 2018

I investigate how the direct investment of foreign firms in the United States affects public opinion on immigration. On one hand, when foreign firms invest in the United States, local residents may have job opportunities and a better understanding of foreign cultures following social and work‐related interactions with foreign employees at multinationals. As a result, American workers may have a positive attitude toward immigration. On the other hand, when local residents see foreign investment as a foreign acquisition of American assets, or if they experience any unpleasant interactions with foreign nationals at multinationals, foreign investment may result in a negative impact on public perception on immigration. My empirical test of inward investment's impact on public opinion demonstrates the aforementioned contrasting impacts: While more local employees working at foreign multinationals lead to positive sentiments on immigration, the existence of more local affiliates of foreign firms has a negative impact on public opinion of immigration.
Family functioning and psychological outcomes in emerging adulthood: Savoring positive experiences as a mediating mechanism
Authors: Cheung Rebecca Y. M. , Leung Man Chong , Chiu Hey Tou , Kwan Joyce L. Y. , Yee Lydia T. S. , Hou Wai Kai
Published: September 2018

The present study tested the mediating role of perceived capability of savoring positive experiences in the associations between family functioning and emerging adults’ psychological outcomes, namely, depressive symptoms and life satisfaction. A sample of 167 Chinese emerging adults (112 female) were recruited from two major universities in Hong Kong. Participants were asked to complete a set of self-reported questionnaires. Findings based on structural equation modeling indicated that family functioning and savoring positive experiences were associated with emerging adults’ depressive symptoms and life satisfaction. Results from bootstrapping further suggested savoring positive experiences as a partial mediator between family functioning and depressive symptoms. These findings enriched the literature by suggesting family dynamics and savoring positive experiences as important correlates of psychological outcomes in the Chinese context. Contributions of these findings to the understanding of psychological functioning in emerging adulthood are discussed.
ALBI and P-ALBI grade in Child-Pugh A patients treated with drug eluting embolic chemoembolization for hepatocellular carcinoma
Authors: Carling Ulrik , Røsok Bård , Line Pål-Dag , Dorenberg Eric J
Published: September 2018

Background

Treatment outcome for hepatocellular carcinoma (HCC) is related to tumor burden and liver function. Grading systems assessing liver function need validation in different clinical settings.

Purpose

To evaluate drug-eluting embolic transarterial chemoembolization (DEE-TACE) in Child–Pugh A HCC with respect to albumin-bilirubin (ALBI) and platelet-albumin-bilirubin (P-ALBI) grade.

Material and Methods

Forty-nine patients with Child–Pugh class A, diagnosed with HCC and allocated to DEE-TACE treatment, were retrospectively analyzed regarding tumor and treatment characteristics, radiological response (mRECIST) one month post treatment, overall survival (OS), and adverse events (AEs; CTCAE, grades ≥3) with respect to ALBI and P-ALBI grade.

Results

There were 21 ALBI 1 patients, 29 P-ALBI 1 patients, and 19 patients were both ALBI and P-ALBI 1. Objective response rate was 74% with no statistically significant difference for ALBI (1 vs. 2; P = 0.08), or P-ALBI (1 vs. 2; P = 0.49). OS was 14.8 months (range = 1.7–62.0; ALBI 1 vs. 2: P = 0.08; P-ALBI 1 vs. 2: P = 0.003). OS in responders with ALBI 1 and 2 was 28.9 vs.10.2 months ( P = 0.02), and P-ALBI 1 and 2 was 26.7 vs. 8.6 months ( P < 0.001). In multivariate analyses, both ALBI 2 (HR = 2.4, P = 0.02) and P-ALBI 2 (HR = 3.3, P < 0.01) were negative prognostic factors for survival. There were 15 AEs in 13 patients, with hepatic failure only occurring in ALBI 2 and P-ALBI 2 patients.

Conclusion

P-ALBI grade 1 and 2 differentiated survival in Child–Pugh A patients treated with DEE-TACE. Both grading systems can differentiate survival in patients responding to treatment.
Potential roles of school administrators and community-residing adults in tobacco use prevention in Nigerian college students: a viewpoint
Authors: Nwobi Anthonia U. , Eseadi Chiedu , Agboeze Mathias U , Okoye Onyinyechi E , Iremeka Felicia Ukamaka , Mbagwu Felicia , Ohia Nkiru Christiana , Nwaubani Okechukwu O. , Oboegbulem Angie I. , Akaneme Immaculata N.
Published: September 2018

Tobacco use is a key risk factor for the development of non-communicable diseases such as coronary heart disease, stroke, and peripheral vascular disease. On May 31 every year, World No Tobacco Day is celebrated to draw attention to the health risks and other risks related to tobacco use and to campaign for effective policies to minimize tobacco use. In this paper, we address important issues related to tobacco use, and highlight the potential roles of school administrators and community-residing adults in supporting college students in Nigeria in refraining from tobacco use. We argue that various stakeholders, including school administrators and community-residing adults, have important roles to play in providing community- and school-level support to college students to enable them to refrain from tobacco use. However, research is needed to empirically measure whether and how school administrators and community-residing adults have helped to reduce tobacco use in college students in Nigeria.
Do Mound Height and Pitching Distance Affect Youth Baseball Pitching Biomechanics?
Authors: Fleisig Glenn S. , Diffendaffer Alek Z. , Ivey Brett , Oi Takanori
Published: September 2018

Background:

Pitching injuries continue to be a serious problem, with adolescents now representing the group with the most injuries. Some have proposed that lowering or eliminating the pitching mound in youth baseball may reduce joint stress and subsequent injuries. Another potential risk factor is advancing from youth to adult pitching distance without an intermediate distance.

Hypotheses:

It was hypothesized that for a group of young pitchers, pitching kinetics and kinematics would change with mound height. It was also hypothesized that pitching kinetics and kinematics would change with pitching distance.

Study Design:

Controlled laboratory study.

Methods:

Twenty-one young (12.6 ± 0.5 years) baseball pitchers pitched 5 full-effort fastballs each from 5 different conditions, in random order: 14.02-, 16.46-, and 18.44-m distances from a 25 cm–high mound, 16.46-m distance from a 15 cm–high mound, and 16.46-m distance from flat ground. Pitching biomechanical values were collected with a 12-camera automated motion capture system. Ball velocity and 31 other parameters were computed for each pitch. Data were compared between the 3 mound heights at 16.46 m by use of repeated-measures analysis of variance and paired post hoc t tests ( P < .05). Similarly, data were compared between the 3 distances from the 25-cm mound via repeated-measures analysis of variance and paired post hoc t tests ( P < .05).

Results:

No differences were found in ball velocity, shoulder kinetics, or elbow kinetics associated with mound height. Ten kinematic parameters differed with mound height, including 8 parameters at lead foot contact. Maximum shoulder horizontal adduction torque and maximum shoulder anterior force increased with pitching distance. Only 3 kinematic parameters showed significant differences with pitching distance.

Conclusion:

The hypothesis that shoulder and elbow kinetics would change with mound height was not supported by the data. Several kinematic differences were found, but the majority were at lead foot contact before the rapid, dynamic phases of pitching. Change in pitching distance was associated with slight increase in shoulder kinetics as well as a few kinematic differences.

Clinical Relevance:

Lowering or eliminating pitching mounds in youth baseball would not significantly decrease joint stress and injury risk to young pitchers. However, when available, transition from 14.02-m to 16.46-m to 18.44-m pitching distance may reduce stress on the young throwing shoulder.
Manufacturing and Evaluation of Woodfibre-Waste Plastic Composite Sheets
Authors: Bhattacharyya Debes , Jayaraman Krishnan
Published: September 2018

Plastic products used for packaging are often discarded after a single use resulting in an inexhaustible supply of waste polymeric materials. The stiffness and strength of polymeric materials have been known to improve with the addition of lignocellulosic fibres available in abundance in nature. Hence, composite materials containing natural fibres and waste plastics would result in the reduction of solid wastes and the use of cheap, renewable resources. Composite sheets have been manufactured from Pinus Radiata woodfibre mats produced by a novel mat forming technique and Kerbside waste plastics. The tensile modulus and strength of these composite sheets have been shown to improve with the amount of woodfibres. The formability of these sheets has been assessed through dome forming. The presence of woodfibres reduces the localised thinning while thermoforming, which is a significant advantage since excessively thin areas may cause component weakness and as a result, defective parts. Complex parts have been thermoformed successfully from these composite sheets confirming the enormous potential for their use in industry.
Structure and Properties of Biodegradable Polymers: Rolling Effect in Poly (butylene succinate) Sheets
Authors: Vega-Baudrit J. , Pereira R. , Nakayama K. , Masuda T. , Cao A.
Published: September 2018

Sheets made from poly (butylene succinate) (PBS) were prepared by extrusion. They have been studied under uniaxial drawing as a function of the draw condition. Changes in molecular orientation and crystallinity were investigated using the criteria of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing, sonic modulus, X-ray diffraction, density, birefringence and measurements of % Haze. Rolling improved the thermo-mechanical and dynamic properties of extruded sheets as a result of changes in molecular orientation and crystallinity.
Environmental and Micro-Environmental Influences Affecting the Performance of Polymer Stabilisers
Authors: Pospíšil J. , Pilař J. , Marek A. , Billingham N.C. , Horák Z. , Nešpůrek S.
Published: September 2018

The accelerated testing of the efficiency and longevity of modern stabiliser packages is expected to provide data allowing us to reduce the development cycle in designing future polymer articles for outdoor application within a commercially acceptable time. Acceleration of photooxidation, heterogeneity in polymer degradation, formation of concentration gradients in stabiliser consumption, and the possibility of determining the spatial distribution of stabiliser transformation products or the negative influences accounting for atmospheric pollutants are analysed to minimize misleading data from accelerated tests, and to provide a base giving more information on the chemical and physical processes accompanying the testing of stabilised polymers.
Nanoscale Boehmite Filler for Corrosion- and Wear-resistant Polyphenylenesulfide Coatings
Authors: Sugama Toshifumi , Gawlik Keith
Published: September 2018

We evaluated the usefulness of nanoscale boehmite crystals as a filler for anti-wear and anti-corrosion polyphenylenesulfide (PPS) coatings exposed to a very harsh, 300°C corrosive geothermal environment. The boehmite fillers dispersed uniformly into the PPS coating, conferring two advanced properties: First, they reduced markedly the rate of blasting wear; second, they increased the PPS's glass transition temperature and thermal decomposition temperature. The wear rate of PPS surfaces was reduced three-fold when 5 wt% boehmite was incorporated into the PPS. During exposure for 15 days at 300°C, the PPS underwent hydrothermal oxidation, leading to the substitution of sulfide linkages by sulfite linkages. However, such molecular alteration did not significantly diminish the ability of the coating to protect carbon steel against corrosion. In fact, PPS coating filled with boehmite of ≤ 5 wt% adequately mitigated its corrosion in brine at 300°C. One concern in using this filler was that it absorbs brine. Thus, adding an excess amount of boehmite was detrimental to achieving maximum protection.
On the Response of Stitched Woven S2-Glass/Epoxy Composites to High Strain Rate Compression Loading
Authors: Hosur M.V. , Karim M. R. , Jeelani S.
Published: September 2018

Experimental investigations were carried out to understand the response of stitched/unstitched S2-Glass/SC-15 epoxy composites to high strain rate compression loading using a Split Hopkinson Pressure Bar set-up. Fifteen layers of plain weave S2-glass fabric were used to fabricate stitched/unstitched laminates with a low viscosity room temperature curing SC-15 epoxy resin system. For stitching, a 3-cord Kevlar thread was used. The fabric preforms were stitched through the thickness in a lock-stitch pattern, maintaining a pitch of 6 mm. The fabric was stitched along the length and width, forming a 25.4 mm stitch grid. Four different types of samples were considered. Sample configuration was designated according to the location of the stitch line with reference to the loading direction. Dynamic and static responses of the laminate under compression were compared. Failure modes were studied using optical microscopy. For high strain rate loading, samples of dimension 22.5 × 22.5 × 9.5 mm were tested at five different pressure settings of the Hopkinson Bar Set-up. Results were analysed in terms of peak stress, strain at peak stress, modulus and failure modes. Results of the study showed that, under higher strain rates loading, the stitched laminates exhibited a confining effect. The primary mode of failure for unstitched samples was fibre microbuckling with multiple delaminations. For stitched samples, fibre microbuckling and micro-delaminations were the major modes of failure and were contained within the bounds of the stitch. Overall, stitched laminates will provide increased damage resistance, which will prove very crucial under crash situations.
Thermal Degradation of Polyurethane Bicomponent Systems in Controlled Atmospheres
Authors: Ketata N. , Sanglar C. , Waton H. , Alamercery S. , Delolme F. , Raffin G. , Grenier-Loustalot M.F.
Published: September 2018

Although the thermal degradation of polyurethanes has been extensively studied in the past, the use of a panoply of recent analytical techniques has provided more detailed data and enabled us to confirm prior findings on the thermal degradation of bicomponent polyurethanes.

The thermal behaviour of bicomponent polyurethanes in conditions of controlled atmosphere and temperature was characterized by determining their heat stability by on-line TGA/FT-IR coupling and off-line TGA/TCT/GC/MS coupling in order to identify the volatile compounds released. Degradation residues were analyzed by FT-IR and MALDI-TOF (matrix assisted laser desorption/ionization coupled with time-of-flight) mass spectrometry. A major drawback of these thermoplastic elastomers is that one of the components, isocyanate, is toxic.

Based on the data obtained with model urethane compounds ( p-TI-based) and bicomponent polyurethane polymer (MDI- and PEG-based), we show that the thermal degradations are different. The widespread application of these materials exposes them to extreme working conditions, which is why we propose reaction mechanisms for their degradation.
Structure and Properties of BR Nanocomposites Reinforced with Organoclay
Authors: Wang Shaohui , Peng Zonglin , Zhang Yong , Zhang Yinxi
Published: September 2018

Butadiene rubber (BR)/organoclay nanocomposites were prepared by direct melt mixing of BR and clay modified with different primary and quaternary ammonium salts. BR/pristine clay composite and BR/organoclay nanocomposites were analysed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. The vulcanization characteristics and the mechanical properties of the BR/pristine clay and BR/organoclay composites were investigated. The results showed that the interlayer distance of the organoclays was expanded, which indicated that intercalated BR/organoclay nanocomposites had been prepared. Organoclay effectively accelerated the vulcanization of BR, which was attributed to the intercalatant used to modify the clay. The tensile strength, elongation at break and tear strength of BR/organoclay nanocomposites are much higher than those of gum BR vulcanizate and BR/pristine clay composites. The organoclay modified with dimethyl dihydrogenated tallow ammonium chloride (DDAC) gave the best reinforcement effect in BR of all the organoclays.
Hydrogen Bonding Effects on the Electrical Properties and Phase Morphology of Polyaniline Blends
Authors: Wei Pan , Shenglin Yang , Guang Li , Jianming Jiang
Published: September 2018

Blends of dodecylbenzene sulfonic acid-doped polyaniline (PANI-DBSA) with either polyacrylonitrile copolymer (PAN) or polystyrene (PS) were solution cast. The investigation focused on the interaction between the components, the morphology and the resulting electrical conductivity of blends. The results showed that with the same PANI-DBSA content the conductivity of PANI-DBSA/PAN was higher than that of PANI-DBSA/PS. PANI-DBSA was dispersed uniformly in the PAN matrix and its cluster size was rather smaller than in the PS matrix. This is attributed to hydrogen bonding between the carbonyl groups in PAN and the imine groups in PANI, which should lead to better compatibility between PANI-DBSA and PAN.
Nonlinear Viscoelastic Creep Characterization of HDPE-Rice Husk Composites
Authors: Pramanick A. , Sain M.
Published: September 2018

Rice husk based plastic composites are increasingly being used as deck-boards, railings and other load-bearing materials. Since this material typically contains 40% plastic, and plastics creep with respect to time when they carry load, creep is an important issue here. So the viscoelastic characterization of this material and the prediction of creep as a function time is of paramount importance for the material's long-term commercial success. Creep is a time related deformation but it can also be affected by the stress level and environmental conditions, such as time and temperature. In order to predict the creep of this composite, it is important to derive a relationship between deformation, time, temperature, relative humidity and stress. Nonlinearity can exist in the stress, temperature, and moisture related deformation. In this study, hollow extruded rice husk -HDPE beams were subjected to creep and recovery in flexural mode and the stress related nonlinear creep behaviour of the same was studied phenomenologically. Both linear and non-linear region constants were determined with modified models, and a predictive model was developed. These constants will be used to define, model and predict long-term creep deformation.
Preparation of NBR/Expanded Graphite Nanocomposites by Simple Mixing
Authors: Liu D.W. , Du X.S. , Meng Y.Z.
Published: September 2018

Nanocomposites of acrylonitrile-butadiene rubber (NBR) and expanded graphite (EG) were synthesised by melt mixing. Before being mixed with the NBR, the expanded graphite was first sonicated for 10 h, and the powders obtained were then grounding in a ball mill for another 10 h. Scanning electron microscopy (SEM) of the sonicated graphite layers revealed that the expanded graphite was completely torn into nanoscale sheets. Transmission electron microscopy (TEM) of the NBR/EG composites indicated nanoscale dispersion of the EG within the NBR matrix. The mechanical properties of the NBR/EG nanocomposites showed a remarkable improvement in tensile strength. Dynamic mechanical analysis (DMA) showed that the EG imparted a higher storage modulus and lower glass transition temperature to the NBR matrix. The expanded graphite was effective in increasing the electrical conductivity of the composites.
Modification of Wood Flour with Maleic Anhydride for Manufacture of Wood-Polymer Composites
Authors: Nenkova S. , Dobrilova Cv. , Natov M. , Vasileva St. , Velev P.
Published: September 2018

Composites consisting of synthetic polymers and natural organic fillers have many applications. Plant-based materials, particularly wood, are used as fillers. Most frequently they are added to the polymer in the shape of wood flour or wood fibres. This type of polymer composite allows the possibility of modifying the components in accordance with the requirements of the application.

Modifications to wood flour (WF) were carried out with a 10% solution of maleic anhydride (MA) in acetone in the presence of benzoyl peroxide and dicumene hydroperoxide. Lignin and cellulose were isolated from the WF and modified by the same method as the WF. They were characterized by Fourier Transform infrared spectroscopy and it was proved that there was a chemical reaction between the wood components and MA. This was confirmed by chemical analysis and by a determination of the hydroxyl groups in unmodified and modified WF.

Composites of polypropylene and modified WF were obtained and studied by scanning electron microscopy, transmission electron microscopy, dynamic mechanical analysis and mechanical tests. They showed an improvement in adhesion between the polymer and the modified WF
Preparation and Characterisation of Antistatic Nylon-6 Filled with ZnO Whiskers
Authors: Luo Ming Liang , Lao Guang Rui , He Ji Hui , Zhao Jian Qing , Chen Wei Zhuang
Published: September 2018

Antistatic composites of nylon-6 filled with ZnO whiskers (ZnOw), the surface of which was treated with a coupling agent, were prepared by melting-blend. Electrical, mechanical and rheological properties of the composites were determined and the effect of ZnOw loading level on these properties was determined. The structure, morphology, thermal properties, and crystallisation behaviour were examined in detail by FT-IR, SEM, TGA, WAXD, DSC etc. The results showed that the ZnOw were well dispersed in the nylon-6 matrix and they interacted well with the nylon-6 matrix. The crystallinity, melt temperature, tensile strength and hardness of the composites decreased gradually with increasing ZnOw content, but the antistatic performance, processing properties and thermal stability improved.
Application of the “Theory of Mixtures” to Temperature – Stress Equivalency in Nonlinear Creep of Thermoplastic/Agro-fibre Composites
Authors: Pramanick A. , Sain M.
Published: September 2018

The viscoelastic characterization of agro-filler based plastic composites is of paramount importance for these materials' long-term commercial success. To predict creep, it is imperative to derive a relationship between deformation, time, temperature, and stress. This work is the harbinger in modelling of the nonlinear creep behaviour of two-phase materials, where an extended “theory of mixtures” has been used to describe all the creep related parameters. The stress- and temperature-related shift factors were estimated in terms of the activation energy of the constituents. The combined effect of temperature and stress on creep strain was accommodated in a single analytical function where the interaction was shown to be additive. The model was validated under rigorous conditions and is unique because it describes creep not through curve fittings, but in terms of the creep constants of the constituents. This constitutive model is not only a vanguard in the prediction of long term creep of many biocomposites but also in the modelling of creep under step loading of temperature.
Preparation and Properties of LLDPE/PMVS Blends
Authors: He Jihui , Ye Hua , Liu Shumei , Zhao Jianqing
Published: September 2018

Reactive blending has been carried out by the melt mixing of linear low density polyethylene (LLDPE) and silicone rubber containing vinyl group (PMVS) to obtain grafted and crosslinked blends. Two methods involving the use of free radicals generated from (a) thermomechanical shear and (b) peroxide decomposition were used to prepare the LLDPE/PMVS blends. The occurrence of grafting and crosslinking of the PMVS molecular chains was deduced by considering the mixing torque, solvent extraction data and evidence from the Fourier transform infrared spectra (FTIR), as well as differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The experimental results indicated that reactive blending significantly improved the interfacial adhesion between the two phases and that peroxide decomposition had a higher initiation efficiency in respect of grafting and crosslinking than thermomechanical shear.

Thermogravimetric analysis (TGA) showed that reactive blending with PMVS improved the thermal stability of LLDPE. Dynamic rheological behaviour and melt flow rate (MFR) results suggested that grafting and crosslinking between the two components increased the viscoelasticity of the blends and the addition of PMVS improved the processability of the LLDPE.

Crosslinking by peroxides gave a higher tensile strength than thermomechanical shear but a lower elongation at break. The limiting oxygen index (LOI) test indicated that the flame retardancy of the LLDPE/PMVS blend increased with increasing amounts of PMVS.
Numerical Modelling of Design Parameters for Manufacturing Polyester/Glass Composites by Resin Injection Pultrusion
Authors: Jeswani A.L. , Roux J.A.
Published: September 2018

Resin Injection Pultrusion (RIP) is an automated, continuous process and is one of the most cost-effective methods for manufacturing composite materials with constant cross sections (such as rod stock, beams, channels and tubing). In the present work, a 3-D finite volume technique was developed to advance the liquid resin flow front through the fibre reinforcement in the injection pultrusion process. The objective of this study was to improve fibre reinforcement wet-out and thus the quality of the pultruded part in an injection pultrusion process.

The complete wet-out of the dry reinforcement by the liquid resin depends on various design and process parameters. The design parameters explored in this study were the aspect ratio of the final composite, injection slot width, injection slot location from inlet of injection chamber, and location of the multiple injection ports. The numerical model simulates the flow of polyester resin through glass rovings and predicts the impact of the design (geometric) parameters on wet-out, resin pressure field, and resin velocity field. The location of the liquid resin flow front has been predicted for an injection slot, as well as for five discrete injection ports.
Effect of Solvents on the Morphology of Electrospun Atactic Polystyrene
Authors: Shin Dong Soo , Lee Se Geun , Lyoo Won Seok
Published: September 2018

Samples of atactic polystyrene (a-PS) were dissolved in tetrahydrofuran, N, N-dimethylformamide and chloroform with tetrahydrofuran and N, N-dimethylformamide as co-solvents and electrospun to dentify precisely the effect of solvent properties like viscosity and boiling point on the morphologies of the electrospun polymers. The forms of bead, bead-onto-fibre, and fibre were prepared and their stable formation conditions were established through a series of electrospinning experiments under various processing conditions. At low concentrations of the a-PS solution in tetrahydrofuran and chloroform, half hollow spheres and collapsed spheres were obtained whereas “apple” type spheres, resembling apples, were obtained in N, N-dimethylformamide. In contrast, web composed of uniform microfibers were prepared at higher concentrations. These results were attributed mostly to differences in evaporation rates and in the viscosities of the solvent and the solutions. In conclusion it is possible to obtain a-PS webs having various fine morphologies by controlling the processing parameters during electrospinning.
In-Plane Mechanical Properties of a Carbon-Epoxy Composite Laminate at Elevated Temperatures
Authors: Zhou Z.Q. , Liu X.L. , Chiu W.K.
Published: September 2018

This paper deals with the experimental determination of the in-plane mechanical properties of a carbon-epoxy composite laminate in the temperature range of 100 °C to 150 °C. Focus has been on the in-plane shear modulus of the laminate. A time-dependent constitutive model for the in-plane shear modulus has been developed. Material constants for the model were derived from the creep compliance of the laminate, obtained experimentally at various temperatures. The results show that the in-plane shear property of the composite laminate is linear viscoelastic within the temperature range and loading level investigated. The constitutive model was validated experimentally.
Mechanical and Thermal Properties of Nano-Composites of Poly(Vinyl Chloride) and Co-Poly(Vinyl Chloride-Vinyl Alcohol-Vinyl Acetate) with Montmorillonite
Authors: Bibi Navida , Sarwar Muhammad Ilyas , Ishaq Muhammad , Ahmad Zahoor
Published: September 2018

Nano-composites of poly(vinyl chloride) and co-poly(vinyl chloride-vinyl alcohol-vinyl acetate) with clay were prepared by the solution intercalation method. Montmorillonite, a three-layered clay mineral consisting of silicate sheets, was employed as reinforcing phase. Compatibilisation between the two phases was achieved by intercalation of montmorillonite with dodecylamine to increase the organophilicity of the clay. Thin films of pure polymers and their composite materials containing various proportions of clay were obtained by evaporation of the solvent. After further drying under vacuum, these films were characterised for their mechanical and thermal properties.

The results have shown that the modulus and the tensile strength of the composite films increased initially compared to the pure polymers and then decreased upon further addition of the clay. The glass transition temperature of the films, measured from the maxima of the tanδ curves using dynamic mechanical thermal analysis, showed a greater shift towards higher temperatures in copolymer-clay than in PVC-clay films. This is indicative of a higher degree of interaction between the two phases of copolymer-clay composites than PVC-clay composites. The microhardness values and the decomposition temperatures also increased in both systems with the addition of an appropriate amount of the clay.
Gelatin-G-Poly(Sodium Acrylate-co-Acrylamide)/Kaolin Superabsorbent Hydrogel Composites: Synthesis, Characterisation and Swelling Behaviour
Authors: Marandi G. Bagheri , Hosseinzadeh H.
Published: September 2018

A novel superabsorbent hydrogel composite based on gelatin has been prepared by graft copolymerisation of acrylic acid and acrylamide in the presence of kaolin powder, using methylene-bisacrylamide (MBA) as a crosslinking agent and ammonium persulfate as an initiator. The synthetic variables affecting the water absorbency of the resulting superabsorbent composite were studied and the composite structure was confirmed using FT-IR spectroscopy. A new absorption band at 1728 cm−1 in the composite spectrum confirmed the presence of a kaolin-organic polymer linkage. The effect of kaolin content and MBA concentration showed that increasing these parameters decreased the water absorbency of the superabsorbent composite. The swelling measurements were conducted in aqueous salt solutions. Results indicated that the swelling ratios decreased with an increase in the ionic strength of the salt solutions. The pH of the various solutions also affected the swelling of the superabsorbent. Finally, the swelling kinetics of synthesised composites with various absorbent particle sizes was briefly examined.
Service Life Prediction of Gfrp Rebars in an Alkaline Environment
Authors: Won Jong-Pil , Lee Su-Jin , Jang Chang-Il , Won Cheol
Published: September 2018

This study proposes a model that predicts the degradation of a GFRP rebar exposed to an alkaline environment, and based on this estimate, predicts the service life of the GFRP rebar. The alkaline environment was a pH 12.6 solution of 0.16% calcium hydroxide, 1% sodium hydroxide, and 1.4% potassium hydroxide, and the GFRP rebar was immersed for 300 days.

We performed a tensile test to measure the degradation. The measured tensile strength for each time period was the remaining residual tensile strength (as a percentage) of the reinforcing GFRP rebar under a controlled state. The time shift factor was taken as the time at which the residual tensile strength was 80% of the control strength. A rebar immersed in an alkaline solution for 300 days at 80 °C was calculated to have a TSF of 13,125 days, or about 36 years, under normal South Korean regional conditions, based on the statistics of Korea's mean annual temperature. This study provides a more appropriate model for the environment of Korea than the one suggested by Dejke.
Continuous Consolidation of Polypropylene/Glass Fibre Commingled Fabric
Authors: Borazghi Hossein , Trudel-Boucher David , Denault Johanne , Fisa Bo
Published: September 2018

Continuous consolidation of a polypropylene/glass fibre commingled fabric has been investigated using the roll forming process. For this manufacturing process, unconsolidated heated plies are progressively consolidated by passing through a series of rollers. First, compaction trials (performed to determine the most suitable processing parameters) have shown that the repeated application and release of pressure can significantly improve the level of consolidation by allowing trapped air to escape from the molten resin. The influence of the roller gaps, laminate temperature and processing speed has then been determined for the roll forming process. Quality of consolidation was assessed by observing polished micrographs of cross-sections and by determining the void content and flexural properties. Results showed that a roll gap sequence starting at 50% of the unconsolidated laminate thickness is satisfactory. For smaller roller gaps, results have shown that the fabric structure is altered by the squeezing flow of the resin. Results also showed that materials with high inlet temperatures and low process speeds have better levels of consolidation due to lower matrix viscosity and longer contact time with the rollers. Using optimum process parameters, continuous consolidation of 4 plies of 1485 g/m2 fabric at a rate of 0.5 m/min led to a satisfying quality of composite, with less than 4% void content.
E-Glass/Phenolic Prepreg Processing by Solvent Impregnation
Authors: Akbar Sohaib , Ding Chen Yan , Yousaf Irfan , Khan Hayat M.
Published: September 2018

The increased interest in polymer matrix composites is partly due to their vast application in aeronautical and aerospace engineering. The preparation of prepreg is frequently the first move in the manufacture of parts. Although industry has developed reliable and successful processes yet there is a need for further scientific investigation because most existing methods have been devised from practices based on trial and error. This paper reports a new approach to the design and operational features of prepregging machines. Our understanding of the subject is then utilized for the production of E-glass/phenolic prepregs. Characterization of manufactured prepregs by resin content, solvent contents, extent of impregnation and tack and drape properties permits comparison of different operational cycles and design parameters. The results have confirmed the success of our approach of successive decreases in the pressure of the squeezing roller in the soaking zone and successive increases in the chamber temperatures in the drying zone. This idea can be utilized in standard engineering operations to describe the operation protocol for the equipment and to give criteria for setting up the impregnation process, along with the design conditions for prepreg manufacturing.
Silicon-Organic Polyepoxides with Epoxy Side Groups Modified with Chelates
Authors: Lekishvili Nodar , Samakashvili Shorena , Lekishvili Giorgi
Published: September 2018

New silicon-organic polyepoxides containing epoxy side groups attached to their main chains have been synthesised by hydride addition (hydrosilylation) of dihydrosiloxanes with the diallyl ether of an epoxidised glycerol group situated at the tertiary carbon atom. General features of the reaction were studied and its kinetic rate constants and reaction order determined. The relative reactivities of various dihydridesiloxanes in the hydrosilylation reaction were determined. The modification of the polyepoxides introduced chelates containing Cu, Ni, Mn and Co atoms into the main chain.

The composition and structure of the synthesised polymers were established from elemental, IR and NMR spectral analyses and from DSC, DTA and TGA data. It was established that the glass transition temperature (Tg) and thermo-oxidative stability of the chelate-containing polymers considerably exceeded those of the unmodified polyepoxides.
Fatigue Properties of Highly Oriented Polypropylene Tapes and All-Polypropylene Composites
Authors: Barkoula N.-M. , Alcock B. , Cabrera N.O. , Peijs T.
Published: September 2018

This paper describes the fatigue behaviour of newly developed all-polypropylene (all-PP) tapes and composites, with reference to the composite processing conditions, testing temperature and making a comparison with commercial alternatives. All-PP tapes are highly oriented and their failure behaviour follows that of other highly oriented polymers. All-PP woven composites fail ultimately due to PP tape failure. However, this failure mode is accompanied by delamination of fabrics in the woven structure. Consolidation pressure plays a decisive role in controlling the interlaminar properties and hence the delamination resistance and furthermore the fatigue limit of the composite. Comparison of all-PP woven composites with commercial alternatives based on glass and natural fibres reveals the excellent relative performance of all-PP composites under fatigue loads. Fatigue properties of all-PP composites are however sensitive to the testing temperature, and elevated temperatures can lead to a rapid reduction of the fatigue resistance of these all-polymer systems.
Synthetic Zinc Oxide Nanoparticles as Curing Agent for Polychloroprene
Authors: Sahoo Suchismita , Kar Sritama , Ganguly Anirban , Maiti Madhuchhanda , Bhowmick Anil K.
Published: September 2018

Zinc oxide nanoparticles were synthesised by a homogeneous precipitation and calcination method. Their dimensions were in the range of 30 – 50 nm. Their performance as curing agent for polychloroprene rubber was compared to that of rubber grade zinc oxide. The tensile strength was observed to increase by 30% and elongation at break by 10%, with the tensile modulus almost unaltered. The crosslink density was increased by 15% and the dynamic modulus at 25 °C was also 10% higher for the nanocomposites. The results from FTIR spectrometry and volume fraction of rubber in the swollen gel supported the fact that there was an increased interaction between the rubber and ZnO for the nanocomposites.
Effect of Clay Modification on Photooxidation of Polyethylene/Clay Nanocomposites
Authors: Qian Zhongzhong , Zhang Shimin , Yang Mingshu
Published: September 2018

In this paper, effect of clay modification and the resultant clay dispersion and orientation structure on the photooxidation of polyethylene has been investigated upon ultraviolet exposure using the technique of infrared spectroscopy. Polyethylene/clay nanocomposites have been prepared using different clay modification. Both the pristine MMT clay and CTAB ammonium intercalated clay were modified via grafting reaction of silane with hydroxyl groups on the clay edge. The grafting modification leads to decreased photooxidation rate compared with that of neat PE, while the pristine MMT and ammoniums accelerate the photooxidation rate of the corresponding composites. Effect of the dispersion and orientation structure of clay in polymer matrix has also been discussed. In addition, the influence of photooxidation behavior on crystallization and morphology of the composites was studied by means of DSC and SEM.