bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the Structural Organisation of Abrasive Composites Based on Ultrahigh-molecular-weight Polyethylene and Natural Diamond Powders
Authors: Shits E.Yu. , Semenova E.S. , Koryakina V.V. , Okhlopkova A.S.
Published: September 2018

A study was made of the structural features of composite diamond-containing materials (CDMs) of abrasive designation, based on ultrahigh-molecular-weight polyethylene (UHMWPE) and natural diamond powders (NDPs), and their effect on the physicomechanical properties of the composite and the service characteristics of the tool. It was established that the composition of the composite is directly responsible for the parameters of the structure formed. It was shown that an increase in the degree of crystallinity and a reduction in the size of the supermolecular formations of the polymer binder lead to an increase in the physicomechanical and service characteristics of the material.
The Service Properties of Composites of Polypropylene and Ochre
Authors: Teryaeva T.N. , Kas'yanova O.V.
Published: September 2018

The service properties of polymer composites based on polypropylene with a dispersed mineral filler – ochre, produced in the Kuzbass – were investigated.
Controlling the Structure and Properties of Non-Woven Materials with Composites Based on Interpolymer Complexes
Authors: Kovalenko G.M. , Bokova E.S. , Andrianova G.P. , Blieva M.V.
Published: September 2018

This study addresses problems of developing fibrous porous materials with a high water vapour sorption activity, intended for the manufacture of footwear, clothing, and also medical products. It is suggested that non-woven fibrous materials modified with hydrogels of interpolymer complexes based on polyacrylic acid and polyvinyl alcohol be used as such materials. The influence of the conditions under which the interpolymer complexes are produced on the structure and properties of the composite materials is investigated.
Hardness and Wear Resistance of Certain Polyolefins with Additions of Molybdenum Disulphide
Authors: Gordienko V.P. , Sal'nikov V.G. , Podlesnyi R.V. , Kasperskii A.V.
Published: September 2018

The possibility is shown of increasing the hardness and wear resistance of crystallising polyolefins by introducing a highly dispersed (<1 μm) additive – molybdenum disulphide (0.1–10.0 vol%) – into the polymers. The wear resistance of the polymeric materials depends on the degree of crystallinity of the polyolefins, the hardness of the composites, and also the formation of boundary lubricating layers of molybdenum disulphide.
Photooxidative Degradation of Films Based on a Copolymer of Vinyl Alcohol with Vinyl Acetate and Polyhydroxybutyrate
Authors: Ivanov V.B. , Voinov S.I. , Ol'khov A.A. , Solin M.V. , Vlasov S.V.
Published: September 2018

A study was made of the effect of poly(3-hydroxybutyrate) on the consumption and accumulation of chromophore groups, and also the absorption of oxygen, during the photooxidation of a copolymer of vinyl alcohol and vinyl acetate.
Features of the Physicomechanical Behaviour of Polymethyl Methacrylate Produced Using Prepolymer Solutions
Authors: D'yachkov I.A. , D'yachkov A.I.
Published: September 2018

A study was made of the physicomechanical properties of polymethyl methacrylate (PMMA) produced by the polymerisation of solutions of low-molecular-weight PMMA (grade LSOM) in methyl methacrylate. It was shown that this approach to producing block polymer glass makes it possible to change the flow temperature of the finished material while retaining its physicomechanical characteristics.
Influence of the Composition of the Redox System on the Thermo-Oxidative Degradation of Intercalated Graphites
Authors: Osipchik V.S. , Yakovleva R.A. , Spirina E.Yu. , Obizhenko T.N. , Rybko E.A. , Kondratenko A.V.
Published: September 2018

An examination was made of the influence of the concentration of an oxidative solution of potassium bichromate in sulphuric acid on processes of thermo-oxidative breakdown and the coefficient of swelling of intercalated graphites. It was established that the resistance of intercalated graphites to thermal oxidation depends not only on the concentration of the oxidative solution used for intercalation but also on the graphite/potassium bichromate/sulphuric acid ratio.
Effect of the Association of Nitrogen-Containing (Meth) Acrylic Monomers on their Radical Polymerisation in Aqueous Solutions
Authors: Shirshin K.V. , Kazantsev O.A. , Sivokhin A.P.
Published: September 2018

Processes of association of nitrogen-containing (meth) acrylic monomers in aqueous solutions were examined. The effect of monomer association on the processes of homo- and copolymerisation of the given compounds was shown.
Investigating the Process of Producing Polylactic Acid as the Base Polymer of Biodegradable Plastics
Authors: Fomin V.A. , Korovin L.P. , Beloded L.N. , Kurskii Yu.A. , Shkurenko S.I. , Monakhova E.V. , Petrov A.G.
Published: September 2018

The laws governing the synthesis of polylactic acid were studied, and the dependence of its molecular weight on the production method and the nature of the catalyst used was established.
New Organic Glasses for the Aircraft Industry
Authors: Gorelov Yu.P. , Chmykhova T.G. , Shalaginova I.A.
Published: September 2018

The properties of new types of organic glass – acrylic plates designed for the production of aircraft glazing – are given. The new organic glasses with heat resistance values of 120–150°C are capable of being used at temperatures of up to 200°C, are weather resistant, and possess high resistance to different types of service stress.
Change in the Volume of the Polymer in the Process of Sorption of a Low-Molecular-Weight Substance
Authors: Kalinina I.G. , Gumargalieva K.Z.
Published: September 2018

By the hydrostatic weighing method it was shown that the dissolution of low-molecular-weight substance decabromodiphenyl oxide in specimens of isotactic polypropylene can proceed without any change in the volume of the polymeric substance, i.e. at sorption centres.
Trends and Prospects of the Development of the Chemistry and Technology of High-Molecular-Weight Compounds
Authors: Prokopov N.I. , Zubov V.P. , Gritskova I.A.
Published: September 2018

A brief summary is given of a report, given at the meeting marking the 50th anniversary of the journal Plasticheskie Massy in December 2009, on the latest technologies for polymer synthesis.
Aqueous Dispersions of Vinyl Acetate with Maleic Acid
Authors: Tabakalyan N.B. , Khechoyan S.A. , Nagapetyan E.P. , Voskanyan P.S.
Published: September 2018

Stable dispersions of vinyl acetate with maleic acid with over 40% dry residue were obtained in the presence of water-soluble initiator ammonium persulphate and a stabiliser – a mixture of hydroxyethyl cellulose and surfactant.
Dehydrochlorination of Interpolymer Complexes and Composites of Polyanilines with Poly Acids
Authors: Eriev O.M. , Nabiev A. , Karimova D.A. , Niezov L.N. , Mukhsinova M.I.
Published: September 2018

The temperature ranges of dehydrochlorination (50–180°C) and degradation (320°C and above) of polyanilines have been determined. A study has been made of the thermal stability of polyaniline interpolymer complexes and composites in a wide temperature range. The activation energy of the dehydrochlorination of doped polyaniline specimens has been established.
Influence of the Filler Particle Shape on the Nature of Failure of Polypropylene-Based Composites
Authors: Ponomareva N.R. , Obolonkova E.S. , Goncharuk G.P. , Grigor'ev Yu.A. , Dement'ev A.I. , Serenko O.A. , Bazhenov S.L.
Published: September 2018

An investigation was made of the influence of the filler particle shape on the nature of failure of PP-based composites. It was established that the filler particle shape affects the types of defect formed and the nature of failure of PP-based composites. The introduction of talc or wollastonite particles into PP leads to brittle failure of the composite up to its upper yield point. When spherical particles are used, the material retains plastic properties, and rupture occurs on neck propagation.
Properties of Concentrated Solutions of Polyvinyl Chloride
Authors: Grishin A.N. , Gutkovich S.A.
Published: September 2018

The influence of the molecular weight of suspension polyvinyl chloride on the rheological characteristics of solutions based on it in solvents of different nature is established.
Plasticisation of Polyvinyl Chloride Using Bis-Adducts of Methylene Dioxolanes with Ethane Dithiol
Authors: Ramazanov G.A. , Shakhnazarli R.Z. , Nazaraliev Kh.G. , Guliev A.M.
Published: September 2018

Bis-adducts of gem-dichlorovinyl cyclopropanes with ethane dithiol were synthesised and their effectiveness as an anti-scorching agent for rubber mixtures based on butadiene-styrene rubber was studied.
Positive Impact of Aggressive Factors on the Structure and Properties of Thermoplastic Materials Containing Highly-Disperse Additives of an Inorganic Nature
Authors: Gordienko V.I. , Sal'nikov V.G.
Published: September 2018

This article emonstrates the potential for use of mechanochemical, photochemical and radiochemical exposure of typical thermoplastics (PE, PP) with highly-disperse additives of an inorganic nature to alter the structure and improve the physical/mechanical characteristics of composite materials. The action of these aggressive factors on polymers containing such additives, especially in a nano-form, was found to open up new and positive potential for targeted modification of the structure and properties of high-molecular compounds.
Modelling of the Temperature Field in a Diamond-Containing Composite Material with Organic Matrix
Authors: Kardanova M.R. , Ligidov M.Kh. , Shkhanukov-Lafishev M.Kh. , Yakhutlov M.M.
Published: September 2018

Numerical modelling was used to study the temperature field in a diamond-containing composite material with an organic matrix. An analysis was made of the influence of the thermophysical properties of the binder, and also of the coatings on the diamond grains, on the temperature field in the composite. The results of modelling of a non-stationary temperature field in the diamond tool composite are given.
The Dependence of the Molecular Topological Structure of Polytetrafluoroethylene on the Technological Aspects of Industrial Synthesis. Part 1: Thermomechanical Spectroscopy
Authors: Ol'khov Yu.A. , Allayarov S.R. , Kochetkova G.V. , Dixon D.A.
Published: September 2018

In order to obtain a solutionless complex diagnosis based on thermomechanical analysis, experimental approaches have been developed in the investigation of the molecular topological structure of polytetrafluoroethylene.
Behaviour of Segmented Polyether Urethane Urea in a Humid Atmosphere after Mechanical Loading
Authors: Tereshatov V.V. , Gladkova O.A. , Strel'nikov V.N. , Makarova M.A. , Volkova E.R.
Published: September 2018

The laws governing the mechanical behaviour of plasticised polyurethane ureas in a wide range of air relative humidity are studied. It is shown that, in the presence of a plasticiser lowering the solubility of the rigid blocks in the flexible phase of the polymer, there is an increase in the stability of the mechanical characteristics of polyurethane urea on exposure to a humid atmosphere.
Synthesis and Properties of Polyether Sulphone Ketone Terephthaloyl Di(P-Oxybenzoates)
Authors: Khasbulatova Z.S. , Shustov G.B. , Mikitaev A.K.
Published: September 2018

A method is proposed for synthesising polyether sulphone ketones containing fragments of terephthaloyl-di(p-oxybenzoic) acid.
Interaction of Polyvinylpyrrolidone with Chloroacetamide in an Alcoholic Medium
Authors: Artykova Z.B. , Goryachaya A.V. , Tashmukhamedov R.I. , Gritskova I.A. , Shtil'man M.I.
Published: September 2018

An examination has been made of the conditions under which poly-N-vinylpyrrolidone reacts with chloroacetamide in an alcoholic medium to form an epoxy-containing polymer. It was established that the polymer yield is higher when the reaction is carried out in 1-butanol than in the case of using ethanol as the solvent.
Modification of Filled, Rigid PVC Composites with Polyorganosiloxane
Authors: Markov A.V. , Persits V.G. , Markov V.A. , Anshin V.S. , Romanov A.S.
Published: September 2018

This article looks at the impact of a modifying addition of liquid polyorganosiloxane containing extended alkyl lateral substituents (PENTA-1006) as process lubricant in chalk-filled PVC composites. Demonstrates that this is a good universal process lubricant which improves the conditions for and reduces the energy input into processes of mixing and extrusion of rigid, chalk-filled PVC composites. The strength of the composites is not lessened by this and their material deformation characteristics are significantly improved.
Controlling the Physicomechanical Properties of Films of Polymer Latices and Dispersions with Solutions of Synthetic Tanning Agents
Authors: Blieva M.V. , Andrianova G.P.
Published: September 2018

An examination is made of the effect of synthetic tanning agents on the physicomechanical properties of films of non-ionogenic dispersions of polymers and ionogenic latices when they are used in the production of porous fibrous composite polymeric materials.
Study by Differential Thermal Analysis and Thermogravimetric Analysis of the Heat Stability of Polyethylene Stabilised with Gossypol Derivatives
Authors: Ostanov U.Yu. , Beknazarov Kh.S. , Dzhalilov A.T.
Published: September 2018

Thermal analysis methods were used to investigate high-density polyethylene (HDPE) stabilised with the addition of 0.5–1.0% antioxidant. Antioxidant was produced on the basis of gossypol with hexamethylenediamine (GHMDA) and with urea adduct (GUA).
Influence of the Degree of Dispersion of the Filler on the Shape of the Defects Formed in Composites Based on High-Density Polyethylene
Authors: Ponomareva N.R. , Bairamkulova T.K. , Obolonkova E.S. , Goncharuk G.P. , Budnitskii Yu.M. , Dement'ev A.I. , Serenko O.A.
Published: September 2018

An investigation was made of the influence of the content and size of the rigid filler particles on the mechanical properties of polyethylene-based composites. It was established that the use of fine particles (30 μm) leads to the formation of oval and diamond pores. In composites with larger particles (60, 130 μm), merging of the oval defects promotes the formation of transverse microcracks, which leads to rapid failure of the materials at low degrees of elongation.
Effect of Montmorillonite on the Viscosity of an Epoxy Oligomer
Authors: Akhmatova O.V. , Zyukin S.V. , Xein Wei Yan , Smotrova S.A. , Kerber M.L. , Osipchik V.S. , Gorbunova I.Yu.
Published: September 2018

A study was made of the effect of different nanofillers on the viscosity of an epoxy composite obtained using mechanical mixing and ultrasound.
Acoustic Quality Control in Rubber Compounding
Authors: Michaeli W. , Hopmann C. , Masberg U. , Dering J.P. , May W. , Ochs K. , Rohrßen D.
Published: September 2018

When rubber is compounded in an internal mixer, distinct noises and vibrations occur over the mixing time. Operators of internal mixers often report these characteristic noises, which vary during the mixing process and are directly related to the properties of the compound. Therefore a process monitoring system using vibration measurement has been developed by the Institute of Plastics Processing (IKV) and the company CT Datentechnik GmbH in Nienburg to determine whether the rubber compounding process in an internal mixer can be characterised and controlled with an acoustic fingerprint. An acceleration sensor is mounted to the outside of the mixing chamber to measure and record the vibration. Then the vibration signals are converted from time domain to frequency domain with a Fast Fourier Transform to establish frequency bands that are relevant to the evaluation of the acceleration level. The compounds are tested for their mechanical and rheological properties and the results of the tests are correlated with the acoustic signals. The correlation of acoustic signals and material properties of rubber compounds allows the mixing state during the compounding process to be described. With this knowledge the mixing process can be optimised in order to reduce waste and to shorten the mixing time.
Comparing the Influence of the Manufacturing Process Employed on the Structure and Properties of Low-Density Polyethylene
Authors: Klimov I.G. , Koval E.O. , Agafonova A.I. , Maier E.A. , Kondrat'ev Yu.N.
Published: September 2018

This paper gives the names of the Russian manufacturers of low-density polyethylene, the processes they use and the capacity levels achieved. IR- and NMR-spectroscopy, gel-permeation chromatography and differential scanning calorimetry are used to make a comparison of the structure and properties of the polymers manufactured using a range of processes, based on the standard product grades. Some general inadequacies in respect of the range of products manufactured and their relation to modern market requirements are noted.
Synthesis of Chlorine-Free Oligoorganosilyl Carbodiimides to Create an Si/C/N Ceramic
Authors: Kirilin A.D. , Gavrilova A.V. , Shamina M.G. , Sheludiakov V.D. , Storozhenko P.A.
Published: September 2018

Methods have been developed for the production of chlorine-free oligoorganosilyl carbodiimides through polycondensation of N, N'-bis(trimethylsilyl) carbodiimide with organochlorosilanes or alkoxy-(acyloxy)organochlorosilanes.
Impact of Epoxy Rubbers on the Shape Memory Effect in Epoxy Polymers
Authors: Stroganov I.V. , Stoianov O.V. , Stroganov V.F. , Akhmetshin A.S.
Published: September 2018

This paper examines the potential for the creation of modified epoxy polymer compositions with high elastic-deformation properties possessing a shape memory effect. A methodology for producing and testing these has been determined. Establishes the optimum epoxy polymer compositions to obtain a shape memory effect. Demonstrates the potential for their use in practice.
Introduction to the special issue on necrogeography and physical geography
Authors: Thornbush MJ
Published: September 2018

In this introduction to the special issue on necrogeography and physical geography, a focus on landforms and landscapes is presented and applied to subdisciplinary areas, including geomorphology, climatology, biogeography, and soil science. The primary aim is to present past directions taken in the field by physical geographers and provide further areas for their potential engagement. The seven papers contained in this special issue are lastly conveyed in terms of their contribution to necrogeography as an applied physical geography in cemeteries, although not exclusively.
Improving Scalability of Generic Online Calibration for Real-Time Dynamic Traffic Assignment Systems
Authors: Prakash A. Arun , Seshadri Ravi , Antoniou Constantinos , Pereira Francisco C. , Ben-Akiva Moshe
Published: September 2018

Flexible calibration of dynamic traffic assignment (DTA) systems in real time has important applications in effective traffic management. However, the existing approaches are either limited to small networks or to a specific class of parameters. In this light, this study presents a framework to systematically reduce the dimension of the generic online calibration problem, making it more scalable. Specifically, a state–space formulation of the problem in the reduced dimension space is proposed. Following this the problem is solved using the constrained extended Kalman filter, which is made tractable because of the low dimensionality of the formulated problem. The effectiveness of the proposed approach is demonstrated using a real-world network leading to better state estimation by 13% and better state predictions by 11%—with a 50 fold dimensionality reduction. Insights into choosing the right degree of dimensionality reduction are also discussed. This work has the potential for a more widespread application of real-time DTA systems in practice.
Impact of Distracted Drivers on Individual and Group Behavior of Following Vehicles: A Networked Multi-Driver Simulator Study
Authors: Xu Jing , Lin Yingzi
Published: September 2018

As traffic density increases, drivers experience more interaction situations, with a greater need to react and adapt to other road users. Driver distraction as an impairment on road safety and traffic efficiency has been widely discussed. How distracted drivers affect the performance of other drivers and vehicle platoons in traffic flow, however, remains underexplored. This study examines the impact of a low-taskload distraction (cellphone-texting task) not only on the specific distracted driver’s behavior, but also how this behavior influences other drivers, individually and collectively as a group, through a networked driving simulation platform. The concept of interactive driving and implications of virtual environments using a networked multi-driver simulation platform were the two major facilitating factors for carrying out this study. The performance indicators from 12 driver groups (three drivers per group) in a car-following situation with a distracted driver involved are analyzed and compared with a no-distraction trial. The results presented show that the impacts of a phone-texting distraction in traffic flow differ when observing drivers individually or as a four-driver platoon. This implementation has the potential to lay a foundation for continued interactive driving experiment design and can serve as an experimental tool for new vehicle technology applications that consider collective vehicle behavior.
In-Vehicle Passing Collision Warning System for Two-Lane Highways Considering Driver Characteristics
Authors: Hassein Udai , Diachuk Maksym , Easa Said M.
Published: September 2018

Passing collisions are one of the most dangerous traffic safety problems. These head-on collisions occur when the driver of the passing vehicle is distracted or does not assess the situation appropriately. The purpose of this study is to develop a passing collision warning system (PCWS) for drivers on two-lane highways to prevent passing collisions and improve road safety. This paper presents a framework and algorithm design for a PCWS that ensures that drivers have an adequate sight distance for a safe passing maneuver. The system uses an available radar sensor to detect the closest opposing vehicle traveling in the left lane and calculates its position, speed, and acceleration rate to estimate the time to collision and compare it with the time required for the passing vehicle to clear the lane. Realistic initial time and passing time models were established using actual experimental field data collected using a global positioning system (GPS) data logger device that was installed in the passing, impeding, and opposing vehicles and used to record the position and speed of different passing vehicles at 1-s intervals. The MATLAB simulation was developed and used to replicate real-life passing maneuvers and was also used to create the algorithm for the proposed warning system. The passing maneuver parameters were selected from probability distribution curves based on field data. The simulation model determines the relative distance and speed of the opposing vehicle at four different time intervals. The different factors that impact system accuracy were also examined.
A Case Report of Anticoagulation Management in Acquired Hemophilia Associated With Levofloxacin
Authors: Mor Lori T. , Holley Kristina
Published: September 2018

Purpose:

To report a case of acquired hemophilia secondary to levofloxacin and provide a guide for the use of anticoagulation in acute coronary syndrome.

Case Summary:

A 75-year-old female treated with levofloxacin presented with spontaneous bruising of the upper extremities. Levofloxacin was discontinued and the symptoms resolved. Thereafter, the spontaneous bruising recurred and progressed over a few weeks. The patient was treated with recombinant factor VIIA with a time to recuperation of 3 months. The patient was subsequently found to have ST-segment elevation for which they received unfractionated heparin, ticagrelor, and aspirin prior to bare metal stent placement.

Conclusion:

Hemophilia A is a rare disease associated with high morbidity and mortality. Case studies previously evaluating the association of levofloxacin with acquired hemophilia have shown causality. Initiating anticoagulation in patients with acquired hemophilia has long been a challenge to clinicians as evidence-based guidelines are lacking and bleeding risk may outweigh the benefit of anticoagulation. Furthermore, factor VIII deficiency does not provide additive protection against atherosclerotic plaque formation. This case report supports existing literature associating levofloxacin with acquired hemophilia. Due to the complication of life-threatening bleeds, familiarity with the treatment course following coronary events will allow patients with acquired hemophilia to be adequately and safely anticoagulated.
Intraorganizational Conditions Supporting Social Innovations by Human Service Nonprofits
Authors: Shier Micheal L. , Handy Femida , Jennings Calvin
Published: September 2018

Social innovation is a distinct type of innovation that refers to the efforts of individuals and organizations that help to create opportunities that have a broader impact on a social system and/or the experiences of a vulnerable social group as a whole. This research identifies the intraorganizational conditions that support or hinder efforts by human service nonprofits to undertake social innovations. Utilizing a cross-sectional research design with a random sample of human service nonprofits ( N = 165) in Pennsylvania, the study identifies internal organizational conditions related to cohesion, procedures, and staff engagement that positively predict product, process, and socially transformative social innovations. This study provides empirical evidence of specific internal organizational characteristics that are supportive of social innovations in human service nonprofits. Furthermore, areas for organizational development related to leadership, staff and volunteer engagement, and procedures and processes are identified that support the development and undertaking of social innovations.
Assembling credibility: Knowledge, method and critique in times of ‘post-truth’
Authors: Aradau Claudia , Huysmans Jef
Published: September 2018

Critical approaches in security studies have been increasingly turning to methods and standards internal to knowledge practice to validate their knowledge claims. This quest for scientific standards now also operates against the background of debates on ‘post-truth’, which raise pressing and perplexing questions for critical lines of thought. We propose a different approach by conceptualizing validity as practices of assembling credibility in which the transversal formation and circulation of credits and credentials combine with disputes over credence and credulity. This conceptualization of the validity of (critical) security knowledge shifts the focus from epistemic and methodological standards to transepistemic practices and relations. It allows us to mediate validity critically as a sociopolitical rather than strictly scientific accomplishment. Developing such an understanding of validity makes it possible for critical security studies and international relations to displace epistemic disputes about ‘post-truth’ with transversal practices of knowledge creation, circulation and accreditation.
Polyimides Containing s-Triazine Rings
Authors: Patel H.S. , Patel V.C.
Published: September 2018

A series of new polyimides containing an s-triazine ring have been synthesized via Diels-Alder intermolecular polymerization of 2,6-bis(2-furanyl methyl imino)-4-n-propoxy-1,3,5-triazine with different bis(maleimide) compounds, rather than aromatization of corresponding Diels-Alder products. All the poly(imino-s-triazine imide)s were characterized by elemental analysis, FTIR spectral studies, number average molecular weight (Mn) by non-aqueous conductometric titration and thermogravimetry. Glass fibre reinforced composites were prepared via in-situ Diels-Alder intermolecular reaction between 2,6-bis(2-furanyl methyl imino)-4-n-propoxy-1,3,5-triazine and different bis(maleimide) compounds without evolution of by-products. The composites were characterized by chemical resistivity and mechanical properties.
High Strain Rate Response of S2-Glass/Epoxy Composites with Polycarbonate Facing
Authors: Vaidya U.K. , Kulkarni M. , Hosur M.V. , Mayer Arnold , Dutta Piyush
Published: September 2018

Impact damage is of critical concern in structures using laminated fibre reinforced composites. Thermoplastic polycarbonate (PC) offers high impact resistance and is often used in a variety of applications, including the windshield and canopy of aircraft, pressure windows and automotive parts among others. Impact damage to structures utilizing composites has been an area of constant concern. In the current study, S2-glass/epoxy composite laminates bonded to PC (referred to as ‘S2-glass/epoxy-PC’ or ‘Laminate-PC’) have been investigated for their high strain rate (HSR) impact response. A compression Split Hopkinson Pressure Bar (SHPB) with 19.05 mm (0.75”) incident and transmission bars with dynamic recovery technique was used to test four, six and eight layers S2-glass/epoxy-PC samples. Using dynamic recovery technique on the SHPB, the sample was subjected to a controlled single compressive pulse, providing information on damage evolution. The samples were tested under HSR impact in three directions (with respect to the side facing the incident bar of the SHPB). In the first, the PC faced the incident bar, in the second, the S2-glass/epoxy laminate faced the same, whereas in the third, the loading was in the in-plane direction of the laminate. The HSR impact tests were performed by considering three strain rates - 109, 327 and 544/s - for all the experiments. The results of the investigation showed that providing a PC facing to S2-glass/epoxy laminate is an effective way of obtaining deformation in the PC facing which absorbs a large portion of the incident energy, thereby minimizing any delamination threat to the composite backing. PC acts as a sacrificial layer that can be readily replaced in the application.
Heat Stability and Degradation of Thermostable Prepolymers in a Controlled Atmosphere
Authors: Richer S. , Alamercery S. , Paisse O. , Raffin G. , Sanglar C. , Waton H. , Grenier-Loustalot M.F.
Published: September 2018

The liquid study of propargylic monomers during heat treatment has shown the formation of secondary phenolic products in the reaction mixture. They are in the form of propargyl-phenol and chromene-phenol and could be the weak links in the thermal properties of the final polymer. Moreover, we note some differences between the reactivities of the two monomers, probably related to the nature of the central pivot of the skeleton.

Solid state analyses by FTIR and solid state crossed polarization magic angle spinning 13C NMR have confirmed the structure of the final polymer, and the reaction paths proposed and have enabled the heat cycle used to be validated. Thermal analyses have shown that the fluorine pivot confers the best thermal properties on the crosslinked material and influences the reactivity and degradation mechanisms of the compounds. In addition, the degradation of the crosslinked compounds occurred as a single step for the dipropargyl ether of bisphenol A and as two steps for the dipropargyl ether of hexafluorobisphenol A.
Viscoelastic Properties of Polyethylene Syntactic foam with Polymer Microballoons
Authors: Lawrence Else , Pyrz Ryszard
Published: September 2018

Syntactic foam products are most often made from glass microballoons embedded in a thermosetting polymer matrix, and they have good mechanical and thermal properties. However, the glass microballoons easily break in shear and are therefore very difficult to use for manufacturing methods that cause shearing of the material. Polymer microballoons are an alternative by which it is possible to produce a foamed product using unmodified commercial extruders or injection moulding machines. The present study deals with the viscoelastic properties of extruded polyethylene (PE) and a foam made from PE and approximately 40 volume percent of polymer microballoons. Results are shown from creep tests carried out at three temperatures and with three force levels, and from stress relaxation tests carried out at room temperature and with five deformation levels. The overall conclusion was that for some applications the foam will be the best choice, whereas for others it is more advantageous to use bulk polyethylene.
Photopolymerization of Exo-Methylene-1,3-Dioxolane with Bisphenol-A-Diglycidylether and Methyl Methacrylate Using Photoinitiators
Authors: Sherif M.H. , Klemm E. , Günther W. , Stadermann D.
Published: September 2018

The copolymerization of 2-exo-methylene-4-phenyl, 3-dioxolane with bisphenol-A-diglycidylether and methyl methacrylate using a cationic and a radical initiator is described. The structure of the polymers is elucidated by NMR and IR spectroscopy. Using a cationic photoinitiator the dioxolane structure is maintained in the copolymer and remaining oxirane structures from the bisphenol-A-diglycidylether can be proved. Surprisingly, no complete ring-opening of the dioxolane takes place in the presence of a radical initiator leading to statistical copolymers with methyl methacrylate.
Yielding and Fracture Toughness of Glass Microballoon-Filled Epoxy Composites
Authors: Zihlif A.M. , Ragosta G.
Published: September 2018

The yielding and fracture behaviour of epoxy/glass microballoon composites has been studied as a function of filler content, temperature and strain rate. No increase in elastic modulus, yield stress and fracture toughness was observed. The compressive yield stress of the composites showed strain rate dependence with more than one rate-activated yielding process. The fracture toughness parameters Gc and Kc were found to be temperature insensitive. The variations in the measured mechanical quantities are discussed in terms of the observed morphology and thermal behaviour of the epoxy composites.
Anisotropy Related “Spring-in” of Angled Composite Shells
Authors: Ding Y. , Chiu W.K. , Liu X.L.
Published: September 2018

During the manufacture of curved or angled shell composite structures, the enclosed angle of such structures tends to be reduced after cure. This phenomenon is referred to as “spring-in”. It is believed that such distortion is caused mainly by the significant difference between the in-plane coefficient of thermal expansion (CTE) and the through-thickness CTE. This might result in a larger out-of-plane contraction than the in-plane contraction during the time that a composite structure is cooling down from the curing temperature. In this paper, a 3-D Finite Element Analysis procedure was developed to predict “spring-in” resulting from anisotropy for both thin and thick angled composite shell structures. The results of the FE analysis were evaluated together with those from the analytical study and experimental investigation conducted by Jain at the Cooperative Research Centre for Advanced Composite Structures (CRC-ACS) in Australia. It was concluded, based on these results, that the FE model gives more accurate results than the analytical model, particularly for thicker composite shells. The corner radius effect, shell thickness effect, and lay-up effect on “spring-in”, together with the effect of tool/part interaction on the total distortion were also discussed. Comparison was made with the experimental results reported by Radford and Rennick.
Microstructural Characterisation of a Syntactic Foam
Authors: Lawrence E. , Wulfsohn D. , Pyrz R.
Published: September 2018

Stereological sampling procedures were used to characterize the geometry of the cells of a syntactic foam. The foam, formed by extrusion, consisted of hollow polymeric microballoons in a low-density polyethylene matrix. Estimates of cell volume fraction, number density and the mean and standard deviation of volumes of cells were made using design-based methods, which are generally valid without any assumptions about cell shape. Additionally, the distribution of cell aspect ratio was estimated, assuming ellipsoidal cells with the major axis in the direction of extrusion. In addition to describing the stereological methods used, this paper illustrates how the results of a pilot study can be used to design an efficient sampling protocol.
Synthesis and Properties of Poly(Acrylic Acid)/Montmorillonite Superabsorbent Composites
Authors: Lin Jianming , Wu Jihuai , Yang Zhengfan , Pu Minli
Published: September 2018

A novel superabsorbent poly(acrylic acid)/montmorillonite composite with water absorbency of about 1100 times its own weight (g H2O/g) was synthesized by graft copolymerizing acrylic acid onto ultrafine montmorillonite powder. The influence of the amount of crosslinker, montmorillonite and neutralization degree on the water absorbency of the composites is discussed in this paper.
Anisotropic Behaviour of Knitted Glass Fibre/Epoxy Composites under Compressive and Shear Loading
Authors: Xu Daqing , Huang Zheng-Ming , Ramakrishna S.
Published: September 2018

Te authors have investigated the anisotropic properties of plain weft knitted glass fibre fabric reinforced epoxy composites oriented at different off-axial angles and subjected to compressive and shear loads. The compression test results in the off-axial angles of 0°, 30°, 45°, 60° and 90° indicated that the ultimate compressive strength and compressive modulus were greatest at 0° but decreased at other off-axial angles. The compressive strength was higher than the tensile strength for the knitted fabric composite at any offaxial angle. On the other hand, the shear test results for the same off-axial angles showed that the ultimate shear strength and shear modulus were greatest at the off-axial angle of 60°. A simple analytical model was applied to calculate the compressive strength at any off-axial angle, by using three critical strength parameters, i.e. the compressive strengths of 0° and 90° and the shear strength of 0°. The theoretical strength data agree favourably with our experiments.
Specific Conductive Carbon Blacks in Plastics Applications
Authors: Van Bellingen Christine , Probst Nicolas , Grivei Eusebiu
Published: September 2018

New developments in knowledge of conductive carbon blacks and their conduction mechanisms have led to new plastics compounds. Conductive carbon blacks enable us to make polymers conductive at a ‘low’ or ‘very low’ loading, leading to better mechanical property retention. The ‘in-mixture’ dispersion and the resulting ultimate dispersion quality also influence the final properties. This study shows the impact of conductive carbon blacks (high structure, low and high surface area) on plastics performance, and especially on electrical properties. Some guidelines for compounding are also covered. This understanding gives rise to new applications and provides the tool to select the most appropriate carbon black to fit the application demand.
Effect of Heat Treatment on Thermomechanical Properties of Electron Beam-cured Epoxy Resins
Authors: Zhang Zuo-Guang , Sui Gang , Zhong Wei-Hong , Sun Zhi-Jie
Published: September 2018

The effects of thermal post-treatment on EB-cured epoxy resins have been studied. Dynamic mechanical analyses were performed on samples which differed in EB radiation dose, initiator dosage, molecular weight and distribution. When the EB-cured epoxy resins were heated, the crosslink density increased. The glass transition temperature (Tg) was shifted to a higher temperature and the storage modulus (E’) remained at a high level in the heat-treated samples with increasing temperature. But when the temperature of heat treatment exceeded the trigger temperature of the initiator, an α'-relaxation peak derived from the local thermal curing network was observed in the tan δ curve. When the crosslink density induced by radiation increased, the effect of heat treatment was weakened and the temperature of the α′-relaxation peak gradually decreased. The initiator dosage and molecular weight played an important role in determining the Tg and E′ of heat-treated samples with approximately the same radiation crosslink density. When the polydispersity increased in the heat-treated samples with the same molecular weight, a higher temperature for the Tg and the α'-relaxation peak were both shown. The crosslink density and E′ at high temperatures were higher in the heat-treated samples with broad molecular weight distribution.
A Study on Resin Flow through a Multi-layered Preform in Resin Transfer Molding
Authors: Seong D. G. , Chung K , Kang T. J. , Youn J. R.
Published: September 2018

In resin transfer molding, mold filling is governed by the flow of resin through a preform which is considered as an anisotropic porous media. The resin flow is usually described by Darcy's law and the permeability tensor must be obtained for filling analysis. When the preform is composed of more than two layers with different in-plane permeability, effective average permeability should be determined for the flow analysis in the mold. The most frequently used averaging scheme is the weighted averaging scheme, but it does not account for the transverse flow between adjacent layers. A new averaging scheme is suggested to predict the effective average permeability of the multi-layered preform, which accounts for the transverse flow effect. When the flow in the mold is unsaturated, the effective average permeability is predicted by using the predicted mold filling time and transverse permeability. The new scheme is verified by measuring the effective permeability of the multi-layered preforms which consist of glass fiber random mats, carbon fiber woven fabrics, aramid fiber woven fabrics. Fluid flow through the preform composed of more than two layers with different in-plane permeability shows different flow fronts between layers. The difference in the flow front advancement is observed with a digital camcorder. The predicted flow front is compared with the experimental results and shows a good agreement. It is expected that the effective average permeability can be used for modeling the resin flow through the multi-layered preform.
Effect of Fiber Surface Treatment on Mechanical Properties of Polyethylene / Epoxy Composites
Authors: Higuchi Yuji , Shimizu Tadayoshi , Mizoguchi Machiko , Fukui Tatsuro , Hamada Hiroyuki
Published: September 2018

Tensile and pipe performance tests were carried out on polyethylene/epoxy materials in which the polyethylene fibers were pre-treated to remove the binder and/or sized. The tensile modulus of the composites was increased by pre-treatment, although the tensile strength was almost the same. The knee point stress of the untreated composites decreased on sizing. The strength retention of pre-treated composites was higher than that of composites with both a binder and a size. This difference in pipe performance was caused by the different interphase resulting from pre-treatment and/or sizing.
Evaluation of Glass Fibre/Epoxy Prepreg Quality during Storage
Authors: Ji K. J. , Wei C. Y. , Deng W. H. , Zhang Y. S. , Liu Y. J. , Mao R. Z. , Wang X.
Published: September 2018

This paper reports the characterisation methods used in evaluating the chemical changes in glass fibre/epoxy prepregs during storage in an environment chamber. The specimens were exposed to an environment with a relative humidity of 50% at 25°C for up to 196 days. Various physicochemical analysis methods were used to determine the extent of the changes to the prepregs during storage. These methods include infrared spectroscopy (IR), thermal analysis (TA) and other chemical methods to measure the volatile and insoluble components content. During storage, the chemical reaction occurs between some epoxide groups, which is known as precuring. Results indicate that precuring in the epoxy resin system consumed a considerable number of epoxide groups during the exposure. The epoxide index obtained from IR analysis gives a straight measure of the number of epoxide groups remaining in the prepregs at different stages of the storage. A parameter known as the “precured degree”, defined from the epoxide index, can be used to measure the prepregs’ quality. A set of laminates made from prepregs that had been degraded to different degrees were subjected to flexural and tensile testing. The flexural and tensile properties were significantly reduced as a consequence of the increase in the precured degree for the prepregs. The results show that it is important to control the precuring reaction in epoxy-based prepregs during storage before they are transferred into composite products.
Synthesis, Mechanisms and Kinetics of Formation of Bi-Component Polyurethanes
Authors: Ketata N. , Sanglar C. , Waton H. , Alamercery S. , Delolme F. , Paisse O. , Raffin G. , Grenier-Loustalot M.F.
Published: September 2018

In order to understand the single-step molten state reactivities of a diaromatic isocyanate (4,4’ dPDhenylmethane diisocyanate MDI), the mechanisms and reaction kinetics were modelled using a monofunctional aromatic isocyanate (para-tolyisocyanate p-TI) and hydroxytelechelic polyols (polyethylene glycol PEG) (polypropylene glycol PPG) with variable macromolecular chains and structure (from 200 to 2000 g.mol-1). The molar ratio of reactive functions NCO/OH was set at 1.1. We were able to characterise the bi-component polyurethanes synthesised and identify side products formed (urea, trimer, allophanate…).

The results were obtained by the use of a panoply of classical analytical techniques (NMR, FTIR, HPLC/UV/MS, ESI/MS, DSC) or those more recent in the field of synthetic polymers (MALDI-TOF). This work shows the necessity of using several efficient and complementary techniques in order to understand the molten state reaction mechanisms and kinetics of these complex PU systems.
Preparation and Characterization of Polyaniline Grafted Silica Nanoparticles
Authors: Peng Liu , Weimin Liu , Qunji Xue
Published: September 2018

Polyaniline (PANI) was grafted covalently onto the surfaces of the phenylaminopropyl silica nanoparticles (PASNs) by the in-situ chemical oxidation of aniline with ammonium peroxydisulfate (APS) using a dispersion polymerization method. A percentage of grafting (PG%) of 234.0% and a grafting efficiency (GE%) of 54.1% were achieved, calculated from the results of elemental analysis (EA). The polyaniline grafted silica nanoparticles (PANI-SNs) were also characterized by FT-IR, UV/vis, TEM, XPS and TGA. The four probe conductivities were also measured.
Morphological Characterisation of Natural Fibre Reinforced Thermoplastics (NFRTP) Processed by Extrusion, Compression and Rotational Moulding
Authors: Torres F.G. , Díaz R.M.
Published: September 2018

In this paper we describe a methodology for applying conventional morphological characterization techniques to some of the manufacturing processes of natural fibre reinforced thermoplastics (NFRTP). The composites studied consisted of a matrix of polypropylene or polyethylene, and of discrete jute, sisal and other natural fibres as the reinforcement. Different microscopic techniques have been used to characterize the processing stages and the structure-property relationships during the manufacture of NFRTPs using single screw extrusion, compression and rotational moulding. Important issues in the processing of discrete fibre composites, such as fibre length distributions, fibre orientation and overall fibre dispersion in the matrix have been studied. Transcrystallinity in the case PP/sisal and PP/jute composites has also been reported. In all cases the characterization procedures described here are related to the manufacturing processes studied in each particular case. In fact, a systematic approach to morphological characterization is presented in this study. We believe that all or some of techniques discussed here could be implemented as quality control procedures in the manufacturing of products using NFRTPs.