bluuebunny/crossref_metadata_2025 huggingface dataset:
Randomized Sham-Controlled Trial of Navigated Repetitive Transcranial Magnetic Stimulation for Motor Recovery in Stroke
Authors: Harvey Richard L. , Edwards Dylan , Dunning Kari , Fregni Felipe , Stein Joel , Laine Jarmo , Rogers Lynn M. , Vox Ford , Durand-Sanchez Ana , Bockbrader Marcia , Goldstein Larry B. , Francisco Gerard E. , Kinney Carolyn L. , Liu Charles Y. ,   on behalf of the NICHE Trial Investigators*, Ryan Shirley , Morales-Quezada Leon , Worthen-Chaudhari Lise , Labar Douglas , Schambra Heidi , Kappy Carlyn R. , Kissela Brett , Pratt Whitney
Published: September 2018

Background and Purpose―

We aimed to determine whether low-frequency electric field navigated repetitive transcranial magnetic stimulation to noninjured motor cortex versus sham repetitive transcranial magnetic stimulation avoiding motor cortex could improve arm motor function in hemiplegic stroke patients when combined with motor training.

Methods―

Twelve outpatient US rehabilitation centers enrolled participants between May 2014 and December 2015. We delivered 1 Hz active or sham repetitive transcranial magnetic stimulation to noninjured motor cortex before each of eighteen 60-minute therapy sessions over a 6-week period, with outcomes measured at 1 week and 1, 3, and 6 months after end of treatment. The primary end point was the percentage of participants improving ≥5 points on upper extremity Fugl-Meyer score 6 months after end of treatment. Secondary analyses assessed changes on the upper extremity Fugl-Meyer and Action Research Arm Test and Wolf Motor Function Test and safety.

Results―

Of 199 participants, 167 completed treatment and follow-up because of early discontinuation of data collection. Upper extremity Fugl-Meyer gains were significant for experimental (
P
<0.001) and sham groups (
P
<0.001). Sixty-seven percent of the experimental group (95% CI, 58%–75%) and 65% of sham group (95% CI, 52%–76%) improved ≥5 points on 6-month upper extremity Fugl-Meyer (
P
=0.76). There was also no difference between experimental and sham groups in the Action Research Arm Test (
P
=0.80) or the Wolf Motor Function Test (
P
=0.55). A total of 26 serious adverse events occurred in 18 participants, with none related to the study or device, and with no difference between groups.

Conclusions―

Among patients 3 to 12 months poststroke, goal-oriented motor rehabilitation improved motor function 6 months after end of treatment. There was no difference between the active and sham repetitive transcranial magnetic stimulation trial arms.

Clinical Trial Registration―

URL:
https://www.clinicaltrials.gov
. Unique identifier: NCT02089464.
Associations Between 30-Day Mortality, Specialist Nursing, and Daily Physician Ward Rounds in a National Stroke Registry
Authors: Paley Lizz , Williamson Elizabeth , Bray Benjamin D. , Hoffman Alex , James Martin A. , Rudd Anthony G. ,   on behalf of the SSNAP Collaboration
Published: September 2018

Background and Purpose—

Well-organized stroke care is associated with better patient outcomes, but the most important organizational factors are unknown.

Methods—

Data were extracted from the Sentinel Stroke National Audit Programme of adults with acute stroke treated in stroke hospitals in England and Wales between April 2013 and March 2015. Multilevel models with random intercepts for hospitals were used to estimate the association of each variable with 30-day mortality to estimate the impact of admission to differently organized hospitals.

Results—

Of the 143 578 patients with acute stroke admitted to 154 hospitals, 14.4% died within 30 days of admission. In adjusted analyses, admission to hospitals with higher ratios of nurses trained in swallow screening was associated with reduced odds of death (
P
=0.004), and admission to hospitals with daily physician ward rounds was associated with 10% lower odds of mortality compared with less-frequent ward rounds (95% CI, 0.82–0.98;
P
=0.013). Number of stroke admissions and overall ratio of registered nurses on duty at weekends were not found to be independently associated with mortality after adjustment for other factors.

Conclusions—

If these associations are causal, an extra 1332 deaths annually in England and Wales could be saved by hospitals providing care associated with a ratio of nurses trained in swallow screening of at least 3 per 10 beds and daily stroke physician ward rounds.
Early Mobilization After Stroke Is Not Associated With Cognitive Outcome
Authors: Cumming Toby B. , Bernhardt Julie , Lowe Danielle , Collier Janice , Dewey Helen , Langhorne Peter , Thrift Amanda G. , Green Ashleigh , Mohanraj Rajkumar , Kramer Sharon F. , Churilov Leonid , Linden Thomas ,   on behalf of the AVERT Trial Collaboration group
Published: September 2018

Background and Purpose—

We aimed to determine whether early mobilization after stroke affects subsequent cognitive function.

Methods—

AVERT (A Very Early Rehabilitation Trial) was an international, 56-site, phase 3 randomized controlled trial, conducted from 2006 to 2015. Participants were included if they were aged 18+, presented within 24 hours of stroke, and satisfied physiological limits for blood pressure, heart rate, and temperature. Participants were randomized to receive either usual stroke unit care or very early and more frequent mobilization in addition to usual stroke unit care. The Montreal Cognitive Assessment, scored 0 to 30, was introduced as a 3-month outcome during 2008.

Results—

Of the 2104 patients included in AVERT, 317 were assessed before the Montreal Cognitive Assessment’s introduction. Of the remaining 1787, 1189 (66.5%) had complete Montreal Cognitive Assessment data, 456 (25.5%) had partially or completely missing data, 136 (7.6%) had died, and 6 (0.3%) were lost to follow-up. In surviving participants with complete data, adjusting for age and stroke severity, total Montreal Cognitive Assessment score was no different in the intervention (n=595; median, 23; interquartile range, 19–26; mean, 21.9; SD, 5.9) and usual care (n=594; median, 23; interquartile range, 19–26; mean, 21.8; SD, 5.9) groups (
P
=0.68).

Conclusions—

Exposure to earlier and more frequent mobilization in the acute stage of stroke does not influence cognitive outcome at 3 months. This stands in contrast to the primary outcome from AVERT (modified Rankin Scale), where the intervention group had less favorable outcomes than controls.

Clinical Trial Registration—

URL:
https://www.anzctr.org.au
. Unique identifier: ACTRN12606000185561.
Status of the name Argolis in Insecta
Authors: SWANSON DANIEL R.
Published: September 2018

The purpose of the present notice is to identify and clarify a case of mistaken homonymy surrounding the name Argolis, pertaining to Lepidoptera, Hemiptera, and Coleoptera. It is here demonstrated that “Argolis” (Boisduval 1836: 2) is an incorrect original spelling of Ergolis Boisduval, 1836 (Lepidoptera: Nymphalidae); therefore, Argolis Stål, 1861 (Hemiptera: Reduviidae) is the valid senior synonym of Caunus Stål, 1865, while Argolis Chapuis, 1874 (Coleoptera: Chrysomelidae) remains a junior homonym. The following details summarize the situation:
Biomarkers and arrhythmia recurrence following radiofrequency ablation of atrial fibrillation
Authors: Carballo David , Noble Stephane , Carballo Sebastian , Stirnemann Jérome , Muller Hajo , Burri Haran , Vuilleumier Nicolas , Talajic Mario , Tardif Jean-Claude , Keller Pierre-Frederic , Mach Francois , Shah Dipen
Published: September 2018

Objective

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and radiofrequency catheter ablation of AF (RCAAF) has become increasingly popular. Cardiac stress and inflammation have been associated with AF. This study was performed to determine whether the pre- or post-AF ablation levels of high-sensitivity C-reactive protein (hs-CRP) and N-terminal pro–B-type natriuretic peptide (NT-proBNP) are predictive of AF recurrence.

Methods

This multicenter prospective cohort study involved patients undergoing RCAAF in Switzerland and Canada. The primary endpoint was the recurrence of AF or atrial flutter at 6 months.

Results

Of 202 patients, 195 completed follow-up (age, 57.5 ± 9 years; mean left ventricular ejection fraction, 62%; mean left atrial size, 19.4 cm2). Patients with AF recurrence had larger atrial surfaces and longer total RCAAF times. Both the pre-ablation hs-CRP level and 1-day post-RCAAF NT-proBNP level were significantly associated with an increased risk of recurrence.

Conclusions

The pre-ablation hs-CRP level and immediate post-ablation NT-proBNP level were markers for atrial arrhythmia recurrence after RCAAF. This confirms growing evidence of the role of inflammation in the pathogenesis of AF. These biomarkers appear to be promising stratification tools for selection and management of patients undergoing RCAAF.
Re-reading in stylistics
Authors: Harrison Chloe , Nuttall Louise
Published: September 2018

Cognitive stylistics is primarily concerned with the cognitive processes – mental simulations – experienced by readers. Most cognitive stylisticians agree that experiences of reading texts are dynamic and flexible. Changes in the context of reading, our attentional focus on a given day, our extra background knowledge about the text, and so on, are all factors that contribute to our experience of a fictional world. A second reading of a text is a different experience to a first reading.

As researchers begin to systematically distinguish between the ‘solitary’ and ‘social’ readings that constitute reading as a phenomenon ( Peplow et al., 2016 ), the relationship between multiple readings and the nature of their processing becomes increasingly pertinent. In order to explore this relationship, firstly we examine the different ways in which re-reading has previously been discussed in stylistics, grounding our claims in an empirical analysis of articles published in key stylistics journals over the past two decades. Next, we draw on reader response data from an online questionnaire in order to assess the role of re-reading and the motivations that underpin it. Finally, we describe an exercise for the teaching of cognitive stylistics, specifically applying schema theory in literary linguistic analysis (Cook, 1994), which illustrates the need to distinguish between readings as part of an analysis. Through these three sections we argue that our experiences of texts should be considered diachronically, and propose that the different readings that make up an analysis of a text should be given greater attention in stylistic research and teaching.
Rapid Curing Epoxy Resin and Its Application in Carbon Fibre Composite Fabricated Using Vartm Moulding
Authors: Wang C.R. , Gu Y.Z. , Zhang K.M. , Li M. , Zhang Z.G.
Published: September 2018

A rapid curing resin system made from the diglycidyl ether of bisphenol A epoxy, modified imidazole and modified aliphatic amine was developed. The curing behaviour and following characteristic of the resin were evaluated by differential scanning calorimetric and rheological analysis, respectively. Carbon fibre-reinforced polymer composite (CFRP) laminates using this resin system were manufactured through vacuum-assisted resin transfer moulding (VARTM) under short-term curing schedule. Subsequently, studies were performed on the processing quality, mechanical properties and heat resistance of the composites. The effects of post-cure duration on the interfacial bonding and the properties of the composites were investigated. The results showed that the curing time of a CFRP laminate using the studied resin under 120 °C could be controlled within 13 min with more than 95% curing degree and few defects. There were variations of the mechanical and thermal properties of the composites with different post-cure durations. The optimum properties were obtained after a post-cure process of 60 min, and extended post-cure treatment were detrimental. The corresponding mechanism was discussed from the viewpoint of interfacial bonding between carbon fibre and epoxy matrix.
Preparation of PLLA-SiO2 Composites Using APTMS as a Crosslinking Agent with the Sol-gel Technique
Authors: Zhang Qing
Published: September 2018

Poly(L-lactic acid)-silica composites were prepared using 3-aminopropyltriethoxysilane as a crosslinking agent through the sol-gel technique in this paper. The structure, water absorption, thermal stability and optical properties of the resulting composites were characterized. The effects of reaction parameters (amount of crosslinking agent, amount of stannous octanoate, pH, and the reaction temperature) on the water absorption of composites were investigated. Based on our experiment results, the optimal reaction conditions were obtained. Compared to unfilled poly(L-lactic acid), the water absorption and the thermal stability of poly(L-lactic acid)-silica composites improved greatly. In addition, the resulting composites exhibited excellent optical transmittance in the visible light range, which was comparable to that of unfilled poly(L-lactic acid).
Influence of Liquid Nitrogen Steeping on Mechanical Properties of a Unidirectional Carbon Fiber Reinforced Bismaleimide Composite
Authors: Wang Shaoquan , Dong Shangli , Gao Yu , Ye Zhuyu , Lu Gang
Published: September 2018

The influence of cryogenic environment on mechanical properties of a unidirectional carbon fiber reinforced bismaleimide composite (T700/6421BMI composite) has been investigated in this study. Cryogenic treatment was performed by steeping the T700/6421BMI composite specimens in liquid nitrogen for 0,24,240,480,1200, 1920 and 2400 hours, respectively. After liquid nitrogen steeping treatment, the transverse tension test, three-point bending test, short beam shear test and impact test were carried out to evaluate the effect of steeping time on mechanical properties of the T700/6421BMI composite. The fracture surface morphology of typical specimens was examined by SEM while the chemical variation and interface damage of the composite were characterized by FTIR and DMA. The results indicate that mechanical properties of the T700/6421BMI composite are affected by liquid nitrogen steeping. The bending strength displays a tendency of decreasing firstly then rising with increase in steeping time, and the shear strength exhibits on the contrary. The total impact energy and crack propagation energy of the T700/6421BMI composite increases rapidly in the initial stage and increases slightly as increases LN2 steeping time. It is suggested that the mechanical properties of the T700/6421BMI composite after liquid nitrogen steeping might be dominated by interface state related to steeping time. With the increase in steeping time, the stress concentration in the surface of matrix and fiber induced by coefficient of thermal expansion (CTE) difference increases and might cause interface debonding.
Numerical Simulation of Bird Impact on Fibre Metal Laminates
Authors: Zhu Shuhua , Wang Yuequan , Tong Mingbo , Pan Xiong
Published: September 2018

A finite element model of bird impact on the Fibre Metal Laminates (FMLs) was established with the smoothed particle hydrodynamics (SPH) and finite element method in the software PAM-CRASH. The bird was modeled with the SPH elements in order to avoid the bird mesh distortion. It studied the sensitivities of some important parameters to the dynamic response of bird strike on FMLs, which included the configuration of the FMLs, the orientation of the composite layup, and the type and thickness of the metal. The results of the simulation show that the bird strike ability of the configuration (2/1) is better than the configuration (3/2). The bird strike ability of FMLs with the composite layup [45°/-45°] is better than the composite layup [0°/90°]. FMLs with aluminum alloy 2024T3 and metal thickness 0.4mm is the best for the anti-bird strike. Lastly, the bird strike simulation was carried out for the wing leading edge structures with three different skins, aluminum alloy skin and two FMLs skins. The analysis results show that the bird strike ability of the wing leading edge structures with FMLs skin is greatly improved.
The Effect of Crack Resistance Layer on Ballistic Performance of Laminated Composites
Authors: Zhu Zhenqiang , Wang Rongguo , Yang Fan , Hao Lifeng , Jiao Weicheng , Liu Yang , Zhang Jianguang , Xu Yanling , Liu Wenbo
Published: September 2018

Crack resistance layer, a layer of aramid stuck on the surface of ceramics, can effectively prevent the splashing of fragment of a bullet under attack. It bounds the fragment within the structure and the friction between bullet and ceramics arouses tremendous energy consumption. Here, we compare the impact tests with and without crack resistance layer to investigate the effect of crack resistance layer. By analyzing the friction between bullet and ceramic, the friction mass, and energy absorption, we study the nature of crack resistance layer protection behavior. As the surface density of this structure increases 1%, the impact resistance and energy absorption efficiency are substantially enhanced.
Nonisothermal Crystallization Behaviour of a Novel Cycloaliphatic Microcrystalline Poly(4,4'-Aminocyclohexyl Methylene Dodecanedicarboxylamide)
Authors: Dong Jianting , Fan Zhongyong
Published: September 2018

Nonisothermal melt crystallization behaviour and crystallization kinetics of poly(4,4'-aminocyclohexyl methylene dodecanedicarboxylamide), a novel cycloaliphatic microcrystalline polyamide (named PA PACM12), are investigated by differential scanning calorimetry (DSC). The results show that with decreasing cooling rate, the crystallization peak becomes narrower and shifts to higher temperature, while the crystallization enthalpy increases. The Avrami equation, Ozawa model and Mo method are proved to be suitable to describe the whole crystallization process. Needle-like crystals of PA PACM12 are observed under polarizing optical microscopy (POM), which is in agreement with the characteristics of nucleation type and crystal geometry deduced from the Avrami analysis.
Abrasion Resistance of Concrete Containing Polyolefin Fibers and Silica Fumes
Authors: Cheng An , Lin Wei-Ting
Published: September 2018

This project is aimed to evaluate the abrasion resistance of cement-based composites which comprise polyolefin fibers and silica fume in the mixes. Material variables include water-binder ratio, dosage of silica fume and dosage of polyolefin fiber. Compressive strength, splitting tensile strength and abrasion tests were conducted and discussed. Test results indicate that the inclusion of polyolefin fiber or silica fume in cement-based composites not only increases the compressive strength and splitting tensile strength but also decreases the abrasion loss. The silica fume plays a positive rule on growth of compressive strength, splitting strength and abrasion resistance of cement-based composites due to the pozzolanic and filler effect. However, the distribution of fibers could not be controlled, resulting in a notable lack of uniformity in the specimens. The combination of silica fume and polyolefin fiber improves the strength properties and abrasion resistance than only use of polyolefin fiber. In addition, the modified Los Angeles abrasion test used in this study is suitable for the evaluation of abrasion resistance in cement-based composites. By regression analysis, the good correlations are found between compressive strength and splitting strength, abrasion ratio and compressive strength, and abrasion ratio and splitting strength.
Radiochemical Graft Copolymerization and Characterization of Acrylate Monomers on to Polyethylene Film
Authors: Kaur Inderjeet , Gupta Anupam , Kumari Vandna
Published: September 2018

Functionalization of polyethylene (PE) film by radiation-induced graft copolymerization of ethyl acrylate (EA) and ethyl methacrylate (EMA) has been carried out using a preirradiation technique to develop materials with different degrees of grafting for use in ion separation processes. The influence of reaction conditions such as preirradiation dose, monomer concentration, reaction time and amount of solvent on percentage of grafting (Pg) has been studied and maximum Pg values of EA (144.97%) and EMA (142.35%) were respectively obtained at [EA] = 0.92 mol/L, [EMA] = 0.80 mol/L, total dose = 14.4 kGy and 17.28 kGy at 100 °C in 120 and 180 min. The effect of different monohydric alcohols of varying chain lengths on Pg has also been studied. The modified films have been characterized by FTIR, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. Some selective properties of pristine and grafted PE film such as swelling and ion uptake studies have also been investigated. The grafted films showed better swelling and ion uptake capacity in comparison to the pristine film.
Mechanical Properties and Tribological Behaviour of Retrieved Uhmwpe Tibial Insert in Total Knee Replacement after Implantation 30 Months
Authors: Kang Xueqin , Ge Shirong , Dai Xiaofeng
Published: September 2018

This study was performed to investigate the performance changing of an ultra high molecular weight polyethylene (UHMWPE) tibial insert, which was removed from a 56 years old male patient after 30 months of service. The tibial insert was investigated by using a contact angle goniometer, UMT-2 friction tester and MicroXAM three-dimensional profilometer to characterize the wettability, ball indentation hardness, creep resistance, friction and wear performance. Scanning electron microscopy (SEM) was employed to describe the morphology of the sample surface of unused and retrieved UHMWPE after friction and wear test. Surface differential scanning calorimetry (DSC) was used to calculate the surface crystallinity of UHMWPE. The results showed that the contact angle of retrieved UHMWPE with bovine calf serum was obviously decreased by about 15% compared with unused UHMWPE. The surface crystallinity of retrieved UHMWPE increased 9.6% compared with unused UHMWPE. All of these induced the ball indentation hardness and creep resistance decreased 18% and 31%, the wear loss of retrieved UHMWPE increased 24% compared with unused UHMWPE.
Microwave-Assisted Modification of Cellulose as a Compatibilizer for Pla and Mcc Biocomposite Film: Effects of Side Chain Length and Content on Mechanical and Thermal Properties
Authors: Suchaiya Voravadee , Aht-Ong Duangdao
Published: September 2018

This research focused on the utilization of modified banana leaf sheath (BS) to be used as the compatibilizer for biocomposite films based on poly(lactic acid) (PLA) and 40 wt.% banana leaf sheath microcrystalline cellulose (BS MCC). Two types of cellulose ester, i.e. cellulose butyrate and cellulose laurate were used as a compatibilizer. The cellulose esters were prepared via acylation process under microwave heating. The proper condition for preparing cellulose butyrate was 180 sec of reaction time and 80 watt of microwave power, while the suitable condition for preparing cellulose laurate was 150 sec of reaction time and 160 watt of power output, respectively. These optimum conditions led to the highest percentage of weight increase (%WI) and the absence of the degradation of cellulose. The butyrate and laurate were successfully grafted on the BS MCC which was confirmed by FT-IR and NMR spectroscopy techniques. For biocomposite films, although the increase of cellulose laurate or cellulose butyrate induced the decrease in Young's modulus of 40 wt.% BS MCC/PLA composite, the elongation at break of 40 wt.% BS MCC/PLA composite was increased. Likewise, the presence of 5 wt.% cellulose butyrate or cellulose laurate contributed to the highest tensile properties, especially in elongation at break, when compared to other contents of cellulose ester. According to SEM micrographs, the presence of both cellulose esters can improve the compatibility between PLA and MCC as evidenced by the disappearance of many holes in 40 wt.% BS MCC/PLA composites. Comparatively, cellulose butyrate is an effective compatibilizer for improving the elongation at break of 40 wt.% BS MCC/PLA since it had better compatibility with BS MCC and PLA matrix than cellulose laurate. However, the addition of both cellulose esters, i.e. cellulose butyrate or cellulose laurate, led to the decrease in the degradation temperature (Td) of 40wt.% BS MCC/PLA, particularly when adding cellulose laurate.
Miscibility and Isothermal Crystallization Behavior of Poly-(L-Lactide-Co-Glycolide)/ Poly(ρ-Dioxanone) Blends
Authors: Zhang Xiaojin , Ma Chi , Bai Wei , Xiong Chengdong , Chen Dongliang
Published: September 2018

We prepared a series of blends from solution co-precipitation of poly-(L-lactide-co-glycolide) (PLGA) and poly (ρ-dioxanone) (PPDO) at various mass ratios. Using a scanning electron microscopy (SEM), PLGA and PPDO were revealed to be immiscible. The crystallization behavior of PLGA/PPDO blends was investigated by differential scanning calorimetry (DSC) under isothermal conditions. Through comparing the crystallization exothermic peak location and the PLGA/PPDO blends' shape, the crystallization rate was determined to slow as the temperature increased. We applied the Avrami equation to analyze the primary stage of the isothermal crystallization and obtained relevant crystallization kinetic parameters. The data revealed that the PPDO component acted as nucleation sites in blends and accelerated the PLGA crystallization rate by increasing the crystallization rate constant k and decreasing the half-crystallization time (t1/2). The Arrhenius equation was used to analyze the crystallization's activation energy. Our analysis confirmed that blending with PPDO accelerates PLGA crystallization. Our micrograph imaging of the spherulites via a polarizing optical microscopy (POM) revealed that the PLGA/PPDO blends' crystals were smaller in size but greater in number than that of pure PLGA. This finding indicated that PPDO is a good nucleation agent for PLGA. All these results suggest that it is possible to control the PLGA crystallization rate by adding a PPDO component.
Isothermal Decomposition Kinetic Analysis of Polymethylphenylsilsesquioxane/Epoxy Resin Systems
Authors: Wang Jiangbo , Li Yongyou , Jin Yi , Wang Zhiqiang
Published: September 2018

The decomposition kinetics of polymethylphenylsilsesquioxane/epoxy resin (PMPSQ/EP) systems under isothermal conditions was investigated by thermogravimetric analysis (TGA), and the isothermal kinetics equation was used to describe the thermal decomposition process. The results showed that the activation energy in the case of isothermal decomposition was first raised and then quickly decreased with increasing degree of conversion, both for EP and PMPSQ/EP (FREP) systems. Moreover, the activation energy of FREP in any degree of conversion was lower than that of pure EP. It was caused by the addition of PMPSQ, which accelerated thermal decomposition and promoted the formation of an insulating carbon layer. Thus, the flame-retardant performance of EP system containing PMPSQ was improved.
Impact Fracture Study of Laminated Composite Using Single Edge Notched Bend Specimens
Authors: Rizov V.
Published: September 2018

The results of an investigation of impact fracture in laminated composite material are presented in this paper. Low velocity impact fracture tests were carried out on single edge notched three-point bending (SENB) specimens using a drop-weight rig. An inclined notch was introduced in the SENB specimen in order to generate mixed-mode I/II crack loading conditions. Different mixed-mode ratios were obtained by varying the notch inclination from 10° to 90° with a step of 10°. The SENB specimens were subjected to various impact potential energies by varying the drop-height in order to determine the critical impact potential energy at which the crack growth initiates from the initial notch tip position for each of the considered notch inclinations. The mechanical response of the SENB specimen to impact loading was analyzed using a two-dimensional linear-elastic finite element model. Good agreement was obtained between the predicted contact force – time curve and the measured one at various impact potential energy levels and notch inclinations. The strain energy release rate mode components were computed by the virtual crack closure technique. The composite fracture toughness under impact loading was characterized in terms of the critical dynamic strain energy release rate at the onset of crack growth. It was found that the fracture toughness under impact loading increases with decreasing the notch inclination. This finding was attributed to the increase of mode II component of crack loading. A comparison of the fracture behaviour under impact and static loading was performed. It was found that the fracture toughness under impact loading was between 19% and 23% lower than the static one for the different notch inclinations. Therefore, it was concluded that static fracture toughness should not be used in the fracture mechanics based design of composite structures which are subjected to impact loading during their lifetime.
Effect of Red Phosphorus Masterbatch on Flame Retardancy and Thermal Stability of Polypropylene/Thermoplastic Polyurethane Blends
Authors: Xu Yang , Tang Mengqi , Chen Xiaolang , Chen Man , Yu Jie , Ma Yonghong , Sun Zhidan , Zhang Zhibin , Lv Jun
Published: September 2018

In this work, red phosphorus masterbatch (RPM) was filled into polypropylene/thermoplastic polyurethanes (PP/TPU) blends as a halogen-free flame retardant. The flammability behaviour, thermal stability and mechanical properties were investigated by limit oxygen index (LOI), UL-94 vertical burning, cone calorimeter tests (CCT), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that the addition of RPM improved the flame retardant performance of PP/TPU blends. The LOI values of the composites with RPM were higher than that of the PP/TPU blends, and the UL-94 V-2 rating was achieved for PP/TPU/RPM composites. The CCT results further indicated that the heat release rates (HRR), total heat release (THR), and the CO2 production rate (CO2P) decreased in comparison with the PP/TPU blends. TGA data indicated that RPM greatly enhanced the thermal stability and char residues of PP/TPU blends. The addition of RPM deteriorated the tensile strength of the PP/TPU/RPM composites. However, the impact strength of the composites was improved.
Tributyl Citrate as Diluent for Preparation of Pvdf Porous Membrane via Thermally Induced Phase Separation
Authors: Zhang Zhao-Cai , Guo Chun-Gang , Lv Jing-Lie
Published: September 2018

Poly(vinylidene fluoride) (PVDF) membrane was successfully prepared by PVDF/tributyl citrate (TBC) via thermally induced phase separation (TIPS). TBC was used as diluent for membrane preparation, which is citric acid esters non-toxic, non-odorous, easy to prepare and comparatively cheap. The effects of PVDF content on crystallinity of PVDF and porous structure were investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), mercury porosimetry and pore size analyzer instrument. The results showed that PVDF was most able to crystallize and the membrane pore size became more uniform and smaller at higher polymer content.
Preparation and Characterization of Poly(2-Hydroxyethyl Methacrylate) and Castor Oil Based Uralkyds Interpenetrating Polymer Networks
Authors: Prashantha K. , Rashmi B.J. , Pai K. Vasanth Kumar
Published: September 2018

Interpenetrating polymer networks (IPNs) of poly[2-hydroxyethylmethacrylate] and uralkyd prepolymer were synthesized using benzoyl peroxide as initiator, polyethylene glycol as chain extender, and N,N-methylene bis acrylamide as crosslinker by sequential polymerization method. The concentration of uralkyd (UA) prepolymer and poly[2-hydroxyethylmethacrylate] (PHEMA) were varied and their effects on chemical, mechanical, thermal, and morphological properties of IPNs were investigated. The IPNs glass-transition temperatures increase with increasing PHEMA concentrations. Tensile strength, and shore A hardness increases with increasing concentration of PHEMA while sacrificing percent elongation. Almost all IPNs have shown similar chemical resistance irrespective of composition. Thermo gravimetric analysis (TGA) indicated that increase in PHEMA concentration increases thermal stability of IPNs. Morphological analysis reveals that IPNs reveals heterogeneous and compact morphologies with distinct microphase separation.
The Synergistic Effects of Carbon Black and Carbon Fibre on the Thermal Conductivity of Silicone Rubber
Authors: Wang Jibin , Ni Luping , Li Qiuying , Wu Chifei
Published: September 2018

Silicone rubber (SR) composites filled with carbon black (CB) and carbon fibre (CF) were prepared. The effects of a single filler as well as hybrid fillers on the thermal conductivity (λ) and mechanical properties of SR composites were investigated. It was found that hybrid filler was more effective in increasing λ of the composite, and this effect was more pronounced when the weight ratio of CF:CB was 80:20. The scanning electron microscopy showed the hybrid filler formed a better filler network than single filler in the matrix. SR composites filled with hybrid fillers also possessed better mechanical properties compared with composites filled with only CF.
Effect of Aluminium Nitrate Hydrate on the Crystalline, Thermal and Mechanical Properties of Poly(Vinyl Alcohol) Film
Authors: Luo Yong , Jiang Xiancai , Zhang Weiying , Li Xiao
Published: September 2018

The effect of aluminium nitrate hydrate (Al(NO3)3·9H2O) on the crystalline, thermal and mechanical properties of PVA was studied in this paper. The interaction between Al(NO3)3·9H2O and PVA was investigated by Fourier transform infrared (FT-IR) spectroscopy. The influence of Al(NO3)3·9H2O on the crystalline, thermal, and mechanical properties of PVA was studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing, respectively. The results indicated that Al(NO3)3·9H2O could form interaction with the hydroxyl group on PVA chain. The XRD studies revealed that the crystallites of PVA were destroyed by Al(NO3)3·9H2O. DSC studies showed that Al(NO3)3·9H2O could increase the flexibility of PVA chains and decrease the Tg of PVA. Tensile testing showed that after the addition of Al(NO3)3·9H2O the tensile strength of PVA film decreased and elongation at break increased. All these results show that Al(NO3)3·9H2O has a high plasticizing efficiency for PVA. However, Al(NO3)3·9H2O is a Lewis acid and the acidic property of Al(NO3)3·9H2O would cause the significant decrease of the thermal stability of PVA.
Influence of Silica as an Abrasive on Friction Performance of Polyimide-Matrix Composites
Authors: Xu X.L. , Lu X. , Qin Z.X. , Yang D.L.
Published: September 2018

This study investigated the friction performance of polyimide-matrix composites with various silica powder contents of different sizes. The friction tests were performed on a pin-on-disk tester at various velocities, ranging from 30 to 160 km/h. The experimental results indicate a silica powder size of 0.25±0.05 mm, a sample of 4 wt.% SiO2 demonstrated a high friction coefficient and better wear performance as compared to a sample without silica. The influence of silica content and powder size on the friction coefficient is directly related to the friction velocity. At low friction velocity (30–90 km/h), the friction coefficient increases as the SiO2 content increases, but decreases with increasing SiO2 particle size. At high friction velocity (90–160 km/h), the content and particle size of SiO2 have little influence on the friction coefficient. Experimental results indicate that large SiO2 particles can effectively hinder the motion of third body, which is advantageous to the formation of a compact third body and to the protection of the friction surface.
Properties Evaluation of Repair Mortars Containing EVA and VA/VeoVa Polymer Powders
Authors: Weng Tsai-Lung , Lin Wei-Ting , Li Cheng-Hao
Published: September 2018

The repair of damaged structures is a complicated problem in the construction industry and it is no uniform standard for evaluating the effectiveness of repair materials. Two different redispersible polymer powders, ethylene vinyl acetate (EVA) and polyvinyl acetate-vinyl carboxylate (VA/VeoVa), were added in the repair mortars with two water-cement ratios and three polymer-cement ratios. The effectiveness of repair materials was evaluated according to the physical, mechanical properties and micrographs. Testing program includes setting time, drying shrinkage, thermal expansion, compressive strength, tensile strength, flexural strength, bond strength, X-ray diffraction analysis, scanning electron microscopy observation.

Test results show that the specimens with VA/VeoVa and w/c of 0.5 have highest compressive strength, tensile strength, flexural strength and bond strength. The specimen with EVA also has higher strength than control one at the age of 28 days. The drying shrinkage deformation of VA/VeoVa specimen is close to the control one. The specimens with VA/VeoVa have lower thermal expansion than EVA specimen when the water-cement ratio is 0.5 and there is no difference between EVA and VA/VeoVa specimens for the water-cement ratio of 0.6. The micrographs show that adding polymer powder can reduce the pore and improve the durability.
Non-isothermal Modelling and Optimisation Methodology of the Injection Moulding of Rubber Products
Authors: Baranov A.V.
Published: September 2018

The process of injection moulding is regarded as a combination of separate operations linked by certain process parameters. The first part of this study presents a mathematical model of the non-isothermal flow of rubber mixes along mould sprue channels, taking into account all the main features of the injection moulding process. On the basis of this model, an attempt is made to develop a methodology for optimising the injection stage. Diagrams linking the main process parameters are plotted. The second part of the study is devoted to the final stage of this cycle – the vulcanisation stage. The presented mathematical model of non-stationary heat conduction takes into account the heat evolution from the chemical reaction of vulcanisation and the temperature dependence of all thermophysical properties. On this basis, an attempt to develop optimisation methodology for this stage is presented. Diagrams are plotted that link the main process parameters of the vulcanisation stage with the previous stages of plasticisation and injection.
The Effect of Fiber Loading on the Mechanical Behaviour of Carbon-aramid Hybrid Composites
Authors: Cyriac Genuvin , Paul Bins , Akhil K.T. , Shunmugesh K.
Published: September 2018

In this emerging world the importance of the research on the material science is increasing because of its wide application in the field of aerospace industry, automotive industry, medical fields, military applications etc. The hybrid composites give a balanced mechanical properties when compared to conventional composites. Epoxy composites having a different percentage composition of carbon-aramid hybrid fibers are fabricated by vacuum assisted resin transfer molding. The improvements in the mechanical properties at different composition of carbon-aramid hybrid fibers are studied. 30, 35, and 45 are the percentage composition of carbon-aramid hybrid fibers which are used in order to study the variation in the mechanical properties such as tensile strength and hardness.
Corona Treatment of Filled Dual-polymer Dispersion Coatings: Surface Properties and Grease Resistance
Authors: Ovaska Sami-Seppo , Geydt Pavel , Rinkunas Ringaudas , Lozovski Tadeusz , Maldzius Robertas , Sidaravicius Jonas , Österberg Monika , Johansson Leena-Sisko , Backfolk Kaj
Published: September 2018

Dispersion coating layers consisting of hydroxypropylated starch, 0–30 pph of barrier-grade talc and 0–10 pph of styrene-butadiene latex were subjected to both positive and negative direct-current corona treatments utilizing a specially developed dynamic treatment unit. The effects of the surface composition (barrier coating) on the response to the direct current corona treatment were evaluated by measuring contact angles and determining the surface energy. The effects of corona treatment on the properties of the barrier coating were further determined by measuring the contact angle of rapeseed oil and the grease resistance. It was found that the grease resistance of the corona-treated barrier coatings was substantially lower than that of untreated samples, which was ascribed to holes caused by corona discharge strike-through and to chemical changes on the treated surfaces. The corona treatment lowered the surface energy of the coatings, as indicated by an increase in the contact angles of water and rapeseed oil. Changes in the dispersion part of the surface energy were recorded, particularly after positive treatment voltage, whereas a negative discharge led to greater changes in the polar part of the surface energy. X-ray photoelectron spectroscopy (XPS) tests revealed an increase in the proportion of talc at the surface after corona treatment, which indicates a migration caused by the applied electric field. The peak force tapping mode of an atomic force microscope revealed moderate topographical changes in the coatings and a decrease in surface elasticity, supporting the migration of talc particles. In addition, significant changes in the physicochemical properties of the untreated reverse side were observed.
High Density Polyethylene/Pistachio Shell Flour/Nanoclay Composites - Effect of Accelerated Weathering Conditions on Mechanical Properties, Relative Brightness and Total Colour Change
Authors: Najafabadi M.A. Abedini , Khorasani S. Nouri , Esfahani J. Moftakharian
Published: September 2018

This study investigates the effect of the addition of nanoclay (Cloisite 20A) on some mechanical properties, % relative brightness (ΔLrel) and total colour change (ΔEab) of high density polyethylene (HDPE)/pistachio shell flour (PSF) composites when exposed to accelerated weathering conditions. X-ray diffraction (XRD) patterns of samples containing 3 and 6 per hundred composite (phc) of nanoclay indicated partial exfoliation and intercalation. The tensile modulus and tensile strength of HDPE/PSF composites (without nanoclay) decreased when the exposure time increased to 1500 h, while the tensile modulus and tensile strength increased. For samples with nanoclay, ΔLrel and ΔEab increased upon accelerated weathering conditions up to 500 h, and thereafter remained constant. But results show that ΔLrel and ΔEab increased significantly upon accelerated weathering exposure in HDPE/PSF samples up to 1500 h.

Scanning electron microscopy (SEM) results after 1500 h exposure to weathering condition showed signs of the presence of cracks in samples without nanoclay, unlike the samples with nanoclay.
Facile Synthesis of Core-shell Structured CuS@PANI Microspheres and Electrochemical Capacitance Investigations
Authors: Chen Chunnian , Zhang Qi , Peng Chengyang
Published: September 2018

A core-shelled structure CuS@PANI composite microsphere was successfully synthesized via chemical oxidative polymerization procedure and the electrochemical performance was investigated. The as-prepared composites were characterized by FE-SEM, TEM and XRD, and their particulate structure has been confirmed. Interestingly, the CuS microsphere was not a whole solid but composed of several sheet-like subunits, and the PANI was loosely-coated on the surface of spherical CuS particles. The advantage of this kind of core-shell structure is that PANI has better conductivity, which favors the electronic conductive channels to the CuS cores. Moreover, the loosely-attached PANI could buffer the disadvantages of the volume changes of CuS during the charge-discharge process. The galvanostatic charge/discharge profile shows a specific capacitance of 308.1 F g−1 at a current density of 0.5 A g−1 and the composite retained 71.6% of its initial capacitance after 1000 cycles at a current density of 1 A g−1.
Permeability Customisation through Preform Manipulation Utilising 3D-Printing Technology
Authors: Tonejc Maximilian , Pletz Martin , Fauster Ewald , Schledjewski Ralf
Published: September 2018

The importance of preforming techniques is constantly increasing due to the fast development of liquid composite moulding processes. Besides traditional preforming methods such as tufting and stitching, tackifier based methods have developed rapidly. This paper presents a new methodology utilising 3D-printer technology for fabrics, through preform manipulation and thus enabling in-plane permeability property customisation. Two patterns of 45° and 90° with respect to the predominant permeability direction were printed onto the fabric consisting of parallel thermoplastic polymer melt strands. After a hot pressing stage the resulting preforms were characterised in terms of their in-plane permeabilities with an optical permeameter and compared to the original material's permeabilities. Furthermore a parameterised model is proposed describing the phenomena causing the manipulation by introducing a scale matrix for translating the original material's permeabilities into the permeabilities of the manipulated preforms.
Functionalization and Chemical Linking of Reduced Graphene Oxide or Graphite onto Polyurethane and the Impact on the Tensile Strength and Sheet Resistance of Polymer Composites
Authors: Chung Yong-Chan , Kim Ho-Sung , Chun Byoung Chul
Published: September 2018

Reduced graphene oxide (RGO) or graphite is functionalized with hydroxyl groups for linking to the sides of polyurethane (PU) chains. Blended PU with RGO or graphite is prepared as a control for comparison. The PU composites are compared with respect to their spectroscopic, thermal, mechanical, shape memory, and sheet resistance properties. Scanning electron microscopy images demonstrate the good distribution of functionalized graphene oxide (FGO) or functionalized graphite (FG) particles on the inner surface of the PU. The linking of FGO or FG onto PU does not significantly affect the thermal behavior or shape memory properties but sharply improves the tensile strength of the PU composites without a noticeable decrease in tensile strain. The shape recovery of PU composites remains at approximately 90%, regardless of the FGO or FG content. The FG-linked PU composites exhibit a sharp decrease in sheet resistance as the FG content increases, whereas the sheet resistance of the FGO-linked PU composites does not decrease with increasing FGO content. The control PU composites with blended RGO or graphite show significant reductions in their sheet resistance. Considering the ease of functionalization of the graphite surface and the significant improvement in tensile strength, linking FG onto PU is advantageous for the development of PU composites with low sheet resistance.