bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Processing on Ductility and Strength of Kevlar/Polyethylene Composites
Authors: Zhang Yaolin , Rodrigue Denis , Aït-Kadi Abdellatif
Published: September 2018

Polymerization-filled composites (PFC) and melt-blended composites (MBC) were prepared to compare their mechanical properties. Improved ductility was obtained for PFC resulting from better fiber-polymer interfacial adhesion. On the other hand, ductility decreased upon increasing fiber content and strain rate, while normalized strengths were almost unchanged. This indicates that matrix and composites have similar responses to strain rate. Tensile strengths were compared with several modified models to include the effect of critical fiber aspect ratio. It was found that the numerical integration model with perfect interfacial bond in combination with Rosen's method for the critical fiber aspect ratio gave the best predictions among all the models tested. The results clearly show that the preparation technique has an effect on tensile strength of composites in relation with fiber distribution and interfacial adhesion.
A Comparison between Cure Systems for EPDM/Montmorillonite Nanocomposites
Authors: Zheng Hua , Zhang Yong , Peng Zonglin , Zhang Yinxi
Published: September 2018

Two kinds of ethylene-propylene-diene rubber (EPDM)/organic montmorillonite (OMMT) nanocomposites were prepared with two kinds of cure systems: sulfur and peroxide. The experimental results from X-ray diffraction and transmission electron miscroscopy showed that EPDM intercalated the MMT galleries and the MMT was exfoliated and dispersed uniformly in the EPDM composites cured with sulfur. But the MMT was stacked with several layers and existed in an intercalated structure in the EPDM composites cured with peroxide. The EPDM composites cured with sulfur were opaque and had better mechanical properties, while the EPDM composites cured with the peroxide were semi-transparent. Vulcametric curves showed that the MMT retarded the vulcanization reaction of the EPDM composites cured with the sulfur cure system, and furthermore, gave rise to a marked decrease in maximum torque, indicating a lower crosslink density. This was confirmed by swelling measurements. But the corresponding values of the composites cured with the peroxide cure system were virtually unchanged by addition of the OMMT.
A Note on the Mechanical Characterization of Non-Homogeneous and Graded Vulcanized Rubbers
Authors: Bilgili Ecevit
Published: September 2018

Ample experimental evidence exists in the literature suggesting the spatial variation of mechanical properties of vulcanized rubbers. Although standard testing methods are based on the homogeneity assumption for rubber specimens, some researchers used these tests without modification to characterize the non-homogeneous rubbers. Within the framework of non-homogeneous material models, this paper proves the inadequacy of the standard mechanical tests and suggests the full-field measurement of displacement–strain in deformed rubber specimens for an accurate characterization. This view is theoretically illustrated by analyzing the deformation of a non-homogeneous rubber slab in a standard shear test.
Thermal Conductivity of Needle Punched Preforms made of Carbon and OxiPAN Fibres
Authors: Lee Jae Yeol , Kang Tae Jin
Published: September 2018

The thermal conductivity of preforms made by a needle punching technique has been measured using a tailor-made apparatus. Measurements were carried out in the absence of the matrix resin to find the thermal conductivity of the preforms themselves. The preforms were made with a variety of material compositions and textile structures, and various needle punching densities. Preforms made of woven fabric showed higher thermal conductivity than preforms of felt fabric. Needle punching density had a strong influence on the thermal conductivity. Increasing the needle punching density decreased the thermal conductivity along the in-plane direction, and increased it along through-the-thickness direction. The thermal conductivity in the through-the-thickness direction was about 30% to 50% of that in the in-plane direction, but the differences between the two directions decreased with increasing needle punching. An analytical model for thermal conduction in both directions was devised, and the results were consistent with those of experiments. The thermal conductivity of the rearranged fibres in the punching hole was estimated by parametric studies.
Influence of Electron Beam Irradiation and Step-Crosslinking Process on Solvent Penetration and Thermal Properties of Natural Rubber Vulcanizates
Authors: Madani M. , Badawy M.M.
Published: September 2018

The influence of both beam irradiation and step cross-linking on high abrasion furnace (HAF) carbon black loaded natural rubber (NR) vulcanizates are reported. With irradiation, a higher cross-link density, ν, thermal conductivity, λ, and glass transition temperature, Tg, have been observed for such materials, as compared with the un-irradiated ones. There is also a decreased specific heat capacity, Cp. Meanwhile, the step cross-linking process has a slight effect on the cross-link density, glass transition temperature and thermal properties of these composites. The results of such changes in thermal conductivity are explained with the help of a simple modified model.
Toughening of Polypropylene Highly Filled with Aluminum Hydroxide
Authors: Su Zhanpai , Jiang Pingkai , Li Qiang , Wei Ping , Zhang Yong
Published: September 2018

The flame retardant and mechanical properties of polypropylene (PP), highly filled with aluminum hydroxide (Al(OH)3) and toughened with ethylene propylene diene monomer (EPDM) and zinc neutralized sulfated EPDM ionomer (Zn-S-EPDM), were studied along with their morphology. The PP matrix when highly filled with Al(OH)3 particles can achieve an adequate level of flame retardancy, but there is a decrease in the mechanical properties because of inadequate adhesion between the Al(OH)3 particles and the PP matrix and the strong tendency of the filler to agglomerate. The rubber incorporated in the PP/Al(OH)3 composites has two roles: as compatibilizer and toughening agent. Although ordinary EPDM significantly improves the Izod impact strength of the composites, the tensile properties are much worse because of the weak interfacial adhesion between the modifier and the matrix. Using Zn-S-EPDM instead EPDM, the tensile properties are much improved with only a slight decrease in toughness, because of improvements in the interfacial adhesion between modifier and matrix. SEM micrographs show that the rubber phase is dispersed in the continuous PP matrix and that most Al(OH)3 particles are uniformly distributed in the rubbery phase. Larger, obviously rubbery, domains can be seen in the PP/EPDM/Al(OH)3 ternary composites. Much finer rubbery domains were found in the PP/Zn-S-EPDM/Al(OH)3 composites.
Synthesis and Characterization of Starch and Acrylamides Based Hydrogels
Authors: Chauhan Ghanshyam S. , Kumari Anita , Sharma Rakesh
Published: September 2018

In order to synthesize a wide spectrum of hydrogels for drug delivery and environmental management technologies, starch was graft copolymerized with three acrylamides, viz: acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-isopropyl acrylamide. The synthesis was carried out at two different temperatures, including the gelatinization temperature of starch (70 °C). A redox system, comprising of ammonium persulfate and ferrous ammonium sulfate (APS: FAS = 2.185 mM: 0.255 mM) was used to initiate the polymerization reactions. Using the same reaction conditions that were used to obtain graft copolymers, crosslinked networks of all three acrylamides and starch were also synthesized in the presence of various concentrations of N, N-methylene bisacrylamide as crosslinker, also at two different temperatures. The hydrogels were characterized by FT-IR and thermal studies to ascertain some of their structural aspects, and also to obtain evidence of network formation. Water uptake by hydrogels was studied as a function of time, temperature and pH. Some of the hydrogels were very good absorber of water and it was observed that the synthetic conditions affected their structure; hence their water uptake was also affected. The hydrogels were environment-sensitive and they showed significant volume transitions when small changes were made in their environment.
Capillary Extrusion Rheology and Thermal Stability of EVA/Organomontmorillonite Nanocomposites
Authors: Chen Dazhu , Zhang Weian , He Pingsheng
Published: September 2018

Ethylene vinyl acetate (EVA) co-polymer-based nanocomposites based on organomontmorillonite (Org-MMT) (Nanolin DK) were prepared by melt compounding without any additional compatibiliser. A partially-intercalated partially-exfoliated structure was revealed in the nanocomposites by X-ray diffraction and transmission electron microscopy Attention was paid to the steady shear rheological properties of the nanocomposites via a capillary rheometer owing to the resemblance of its conditions of operation to those prevailing during the practical fabrication process of materials. Increasing the temperature improves the flow properties but decreases the pseudoplasticity of the melts. With increasing shear stress (or shear rate), the shear viscosity (η) and flow activation energy ( Eη) drop while the extrudate swell ratio ( de/ dc) rises. The addition of Org-MMT leads to a reduction in both η and de/ dc of the nanocomposites as compared to the EVA matrix. The thermal stability of EVA and EVA/Org-MMT nanocomposites was also examined by thermogravimetric analysis
Evaluation of the Mechanical and Ultrasonic Properties of Butadiene-Acrylonitrile Rubber Containing Short Aramid Fibres
Authors: Helaly F.M. , El-Sabbagh S.H. , El-latif L. Abd.
Published: September 2018

Short aramid fibres were incorporated into butadiene-acrylonitrile copolymer rubber (NBR). An adhesion system (hydrated silica, resorcinol and hexamethylene tetramine) (HRH) was used to strengthen the bond between the rubber and the fibres. The rheological, tensile, ultrasonic properties and the hardness were determined by standard test methods. The properties of the composites improved as the fibre content increased up to 30 phr by weight.

Longitudinal and transverse ultrasonic velocities were used to calculate the elastic parameters of the composites. Ultrasonic results were then used to assess the bonding between the fibres and the rubber matrix as well as the sound absorptive potential of the composites.

Scanning electron microscopy (SEM) demonstrated that the fibre distribution in the rubber was satisfactory.

Regression analysis was used to clarify the correlation between the longitudinal tensile strength and ageing time. The strain energy increased with fibre content while the fatigue life decreased.
Aromatic Diamines as Cooperative Compatibilizers and Impact Modifiers in LDPE/HIPS Blends
Authors: Pospíšil J. , Michálková D. , Fortelný I. , Kruliš Z. , Šlouf M.
Published: September 2018

Mechanical recycling emerged among other plastics recycling approaches as a profitable method. Its feasibility has enhanced by understanding of reasons of lower mechanical properties of aged materials in comparison with virgin materials, and by a proper exploitation of the knowledge of compatibilization and stabilization additives for upgrading of reused materials. This study deals with low density polyethylene (LDPE). Impact strength of recycled or pre-aged (recyclate model) LDPE / high-impact polystyrene (HIPS) blends compatibilized with styrene-butadiene copolymer / ethylene-propylene elastomer was enhanced and fineness of the phase structure of the system was improved by using N,N'-disubstituted 1,4-phenylenediamine co-additives. Mechanism of the strong synergistic compatibilization effect was explained by LDPE grafting with styrene-butadiene copolymer mediated by the bifunctional amine additive.
Flame Retardancy of Nanocomposites - from Research to Reality
Authors: Beyer Günter
Published: September 2018

Nanocomposites are a new class of polymer systems. Modified layered silicates as fillers are dispersed at a nm-level within a polymer matrix. For nanocomposites new and extraordinary properties are observed. The thermal stability and the flame retardancy of polymers forming nanocomposites are improved. The flame retardancy mechanism of layered silicate nanocomposites is based on the char formation and its structure; the char insulates the polymer from heat and acts as a barrier, reducing the escape of volatile gases from the polymer combustion. The cone calorimeter is a very useful tool to investigate the properties of flame retardancy. The combination of organoclays with traditional flame retardants is a general way to improve the flame retardant properties of polymers.
Effect of Epoxy Resin on the Mechanical Properties and Melt Viscoelastic Behaviour of Poly(butylene terephthalate)/Montmorillonite Nanocomposites
Authors: Wu Defeng , Zhou Chixing , Fan Xie , Mao Dalian , Bian Zhang
Published: September 2018

Poly(butylene terephthalate)/epoxy/montmorillonite ternary nanocomposites (PCNs) were prepared by melt intercalation. Their morphologies were investigated using XRD and TEM. The results reveal that with epoxy resin as a compatibilizer, the clay is easily intercalated and disperses well in the matrix. Therefore, the PCNs exhibited better tensile and impact properties than neat PBT, although any surplus epoxy dispersed in the PBT matrix reduces the material performance.

The melt viscoelastic behaviour of the PCNs was measured by means of a parallel plate rheometer. The PCN ternary hybrids showed a stronger solid-like response in the lower frequencies than samples without epoxy, for two reasons: the enhancement of percolation network density, and the bridge-like effect of the epoxy linking the clay and the polymer chains.

The compatibilizer content influenced the morphology and performance of the nanocomposites. The optimum compatibilizer dosage of 4 wt% was decided by a novel 'crossover point' rheological method.
Preparation and Characterization of Ni2+-Montmorillonite/Polyvinyl Alcohol Water-Soluble Nanocomposite Film
Authors: Wang Li-Ping , Wang Yun-Pu , Zhang Fa-Ai
Published: September 2018

A new type of nano-composite film was prepared from polyvinyl alcohol, Ni2+-montmorillonite (Ni2+-MMT), defoamer, a levelling agent and a plasticizer. Its thermal characteristics were studied by Differential Scanning Calorimetry (DSC). The intermolecular interactions were measured by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the tensile strength (TS) and elongation at break (%E) were measured. The microstructures were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). FT-IR and XPS spectra indicated that cross-linking has taken place between PVA and Ni2+-MMT.

XRD and AFM indicate that the PVA molecules had inserted themselves into the silicate layers of MMT, exfoliating them and dispersing them randomly into the PVA matrix. Compared to pure PVA film, the TS of the films was increased and %E decreased when the Ni2+-Montmorillonite was added and the dissolution temperature of the film was also reduced.
Cylindrical Orthotropic Thermal Conductivity of Spiral Woven Composites. Part II: A Mathematical Model for their Effective Transverse Thermal Conductivity
Authors: Chiu Chang-Hsuan , Cheng Chao-Chuan , Hwan Chung-Li , Tsai K.-H.
Published: September 2018

This is the second in a series of papers on the cylindrical orthotropic thermal conductivity of spiral woven composites. Based on the thermal-electrical analogy, a mathematical model for determining the effective transverse thermal conductivity of spiral woven fabric composites has been developed in terms of geometric parameters and constituent thermal properties. It is shown by a comparison with publishing results that the present model is capable of predicting the effective transverse thermal conductivity of spiral woven composites.
On-line Monitoring of Resin Content and Volatile Content in Carbon/Phenolic Resin Prepreg Cloth by Near-Infrared Spectroscopy
Authors: Li Wei , Huang Yu Dong , Liu Li , Jiang Bo
Published: September 2018

Near-infrared (NIR) spectroscopy has been implemented for on-line monitoring of resin and volatile content during the manufacture of carbon/phenolic resin prepreg cloth. The calibration models were generated using partial least square (PLS) regression to relate the on-line spectral data to the components' content. The models had determination coefficients (R2) of 92.92 for the resin content and of 92.11 for the volatile content. The root mean square errors of prediction (RMSEP) were 0.861% and 0.273% for the resin and volatile content, respectively. The statistical results of the paired t-test revealed that there was no significant difference between the NIR method and the standard analysis method. The resin content and the volatile content were continuously monitored by NIR in the production of the carbon prepreg. The study indicates that NIR spectroscopy is a good alternative for monitoring the quality of carbon prepreg.
Effect of Compatibiliser and Fibre Content on Jute Fibre Reinforced HDPE/EPDM Composites
Authors: Sarkhel Gautam , Banerjee Amarnath , Bhattacharya Pinaki
Published: September 2018

The mechanical and morphological properties of jute fibre reinforced high-density polyethylene (HDPE)/ethylene-propylene-diene terpolymer (EPDM) composites were studied as a function of fibre and compatibiliser content. A remarkable improvement in tensile strength, flexural strength and unnotched impact strength was attained with addition of 2% compatibiliser. With increasing fibre content, the tensile and flexural strength increased but impact strength declined because of the presence of too many fibre ends that could cause crack initiation. Scanning electron microscopy showed that better interaction and distribution of fibres in the matrix was achieved in the compatibilised system than the uncompatibilised one.
Recycling of Polyethylene/Poly(ethylene terephthalate) Post-Consumer Oil Pouches using Compatibiliser
Authors: Choudhury Arup , Mukherjee Mandira , Adhikari Basudam
Published: September 2018

The recyclability of LDPE/LLDPE/PET based post-consumer laminated oil pouches, and the scope for improvement of the properties of the recycled polymer by the addition of reactive compatibilisers are evaluated. Two efficient reactive compatibilisers, viz., a zinc salt of ethylene methacrylic acid copolymer (Surlyn ionomer) and polyethylene graft maleic anhydride (Fusabond) were used. The effectiveness of the compatibiliser in the recycling of laminated oil pouches was evaluated by infrared spectroscopy, melt flow index, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, rheological and mechanical properties. The melt viscosity, thermal stability and mechanical properties of the recycled material were improved to a satisfactory level by the addition of 5 wt% of compatibiliser. The Surlyn ionomer gave better thermal and mechanical properties. The overall performance of the compatibilised recycled oil pouch materials indicates their suitability for several demanding applications.
Melt Densification of Polymeric Powder Beds Filled with Natural Fibres
Authors: Torres F.G. , Carrillo M. , Cubillas M.L.
Published: September 2018

An experimental study of the melt densification of polyethylene powders filled with natural fibres is presented. The aim was to understand the underlying principles applicable to the consolidation of thermoplastic polymer-natural fibre systems processed by rotational moulding. This process has been developed at POLYCOM and has been reported previously in the literature. A sintering oven with PID-controlled temperature was equipped with a stereo microscope and image acquisition facilities. Sintering sequences were studied using image analysis procedures.

Initial studies with two kinds of polymer particle and one type of fibre were carried out in order to identify some of the governing processes. Other studies included the use of multi-particle beds with many fibres having different concentrations, and the measurement of powder permeability and density. The influence of sintering temperature and time on the sintered specimens' density is also reported. Natural fibres induce voids in the sintered specimens and retard coalescence between the polymer particles. The experimental results were in good agreement with previous data obtained from the rotational and compression moulding of natural fibre reinforced thermoplastics.
CMC-g-Poly (Sodium Acrylate)/Kaolin Superabsorbent Hydrogel Composites: Synthesis, Characterization and Swelling Behaviour
Authors: Pourjavadi A. , Ghasemzadeh H.
Published: September 2018

A novel superabsorbent composite system based on carboxymethyl cellulose (CMC) was prepared by graft copolymerization of acrylic acid (AA) in the presence of kaolin powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The effect of reaction variables, such as MBA, AA, and APS concentration and CMC/kaolin ratio on the water absorbency of the composite were studied. Evidence of grafting and kaolin interaction was obtained by comparing the FT-IR spectra of the initial substrates with that of the superabsorbent composite. The results indicated that with increasing amount of kaolin, the swelling capacity was increased and then considerably decreased with further increase in amount. The effect of various salt media was also studied, along with swelling kinetics.
Properties of Polyacrylate/Bentonite Superabsorbent Hybrid Prepared by Intercalated Polymerization
Authors: Zhang Ji , Yuan Kun , Wang Yun-Pu , Gu Sheng-Jiu
Published: September 2018

A hybrid superabsorbent consisting of polyacrylate intercalated bentonite was prepared by solution polymerization with an intercalation step, polymerization and a cross-linking reaction. Partially neutralized acrylic acid was intercalated, polymerized and cross-linked to bentonite. The initiator was potassium persulfate and the cross-linking agent was sugar (from Artemisia seed gum). The structure of the polyacrylate/hybrid was determined by FT-IR and XRD. The results showed that the bentonite was intercalated by the polyacrylate. The layer spacing of the bentonite was enlarged. Various factors, (such as the degree of neutralization, the consumption of monomer, the amount of initiator and cross-linking agent and the amount of bentonite), which affected the resin's water absorbency were studied through orthogonal experiments. In optimum conditions the ratio (by weight) of bentonite to monomer was 1/2, the degree of neutralization was 75% (mol), the initiator content was 3%, and the cross-linker content was 5%. The cost of the superabsorbent was decreased by 30%, whereas its water absorbency was about 120 g/g for water, and 30~36 g/g for saline solution.
Antioxidant Properties of Multiwall Carbon Nanotubes: First Measurements Using a Model Oxidative Reaction
Authors: Zeynalov Eldar B. , Friedrich Joerg F.
Published: September 2018

Carbon nanotubes (CNTs) have electron affinities similar to those of fullerenes and they are therefore capable of acting as radical traps in free radical chain reactions, including polymerisation and the thermo-oxidative degradation of polymers. It is proposed that the CNTs used as integral part of polymer composites are able to interrupt chain propagation, leading to an antioxidant effect in these materials. This is because of their radical accepting capacity.

To support this postulate, the antioxidative activity of commercial carbon nanotubes (denoted by CNT-MW(1b)) has been studied by means of a model reaction, namely the oxidation of cumene initiated (2,2'-azobisisobutyronitrile, AIBN) in the liquid phase. This reaction was designed to simulate the thermo-oxidative processes in carbon-chain polymers and it allows for the comparison and transfer of results to a polymer system. Measurements of oxidation rates showed that the inhibition of the model oxidative reaction in the presence of the original CNT-MW (1b) is very weak over the concentrations range up to 0.05 wt.%. Increasing the CNT-MW (1b) concentration above 0.05 wt. % facilitates catalytical action of the metal (Co) originally contained in the commercial CNT-MW (1b). In general, the rate of oxidation Wo2 depends on two competing reaction rates. These are the rate of inhibition Winh.(CNT) caused by the structure of the CNT and the rate of initiation Wi(Co) due to the interaction ROOH + M (Co) i.e. Wo2 ~ W inh (CNT) + Wi(Co). Nevertheless, experimental explorations under the condition Winh (CNT) >> Wi(Co) allow us to assess the inhibiting parameters of the CNT- MW.

The effective rate constant for the addition of cumyl R· radicals to CNT-MW (1b) was determined to be k [CNT](333–353 K) = (4.0 ± 2.0)·103 s−1. This is an order of magnitude smaller than the constant for their addition to fullerene C60.

The model kinetic data obtained specify the limits of rational use of the carbon nanotubes in polymer composites.
The Preparation and Characterisation of a Novel Siloxane Biomaterial
Authors: Cao Shunsheng , Deng Xiaobo , Liu Bailing , Luo Rong , Chen Hualing
Published: September 2018

It is well known that polysiloxane interacts strongly with proteins and has been shown to adsorb significant quantities of protein due to its strong hydrophobicity, which often promotes conformational and orientational changes in the adsorbed proteins so as to decrease their biocompatibility. Therefore, the control of protein adsorption to biomaterials and the preparation of suitable siloxane biomaterials become necessary and significant for the actual application. In this paper, a novel siloxane biomaterial (siloxane microspheres) was prepared by dispersion polymerization under kinetically controlled conditions. And then, the siloxane biomaterial was characterized by particle size analyser, X-ray Photoelectron Spectroscopy (XPS) and static contact angle.

The siloxane microspheres were used as the matrix, and bovine serum albumin (BSA) as the template protein, the adsorption has been investigated. The study shows that the amount of protein adsorption (BSA) is higher in the prescence of siloxane monomer than than in its absence, and the effects become more evident with the increase in the contents of siloxane monomer. This indicates that its hydrophobicity of siloxane microspheres can be shepherded through the amount of siloxane monomer added.
Optimisation of Precision Injection Moulding Processing Parameters and Implementation of Quality Prediction System for LCD Light Guide Plate
Authors: Kuo Chung-Feng Jeffrey , Su Te-Li
Published: September 2018

The quality of the light guide plate determines the luminance uniformity of liquid crystal display panels. Only through proper control of the injection moulding processing parameters for the light guide plate can make the precision of the light guide plate's dimensions to be improved, thus enhancing the light guide plate's optical properties. The objective of this research was first to discover the optimal combination for the light guide plate's injection moulding processing parameters. The Taguchi method was used to conduct the parameter design and select the control factors within the processing parameters that affect light guide plate quality.

A confirmation experiment with a 95% confidence interval was then adopted to verify the reproducibility. At the same time, a back propagation neural network was applied to set up a quality prediction system for the light guide plate moulding. Its input layer had eight neurons, representing eight control factors. The hidden layer had five neurons. The output layer had one neuron, which was the signal-to-noise ratio of the light guide plate's luminance uniformity. By comparing the neural network's predicted values with the confirmation experiment's actual values, the system's ability to make accurate predictions could be verified.
Biodegradability Enhanced Terpolymer of Propylene Oxide and Ethylene Oxide with Carbon Dioxide Using Zinc Glutarate as Catalyst
Authors: Zou Y.N. , Xiao M. , Li X.H. , Wang S.J. , Meng Y.Z.
Published: September 2018

As an on-going project to synthesise the copolymers of epoxides with carbon dioxide, the ternary polymerisation of propylene oxide and ethylene oxide with carbon dioxide was investigated using an anaerobic system. The terpolymerisation of propylene oxide and ethylene oxide with carbon dioxide was carried out with supported zinc glutarate catalyst, consequently producing high molecular weight poly(propylene-ethylene carbonate) (PPEC). The structure and properties of PPEC were studied by means of gel permeation chromatographic (GPC) analysis, Fourier Transform infrared (FTIR), nuclear magnetic resonance (NMR) spectroscopy, different scanning calorimetry (DSC), and thermogravimetric analysis (TGA) techniques. NMR and FTIR results showed that the terpolymer PPEC was a polycarbonate consisting of propylene carbonate and ethylene carbonate together with random ether linkages. The glass transition temperature (Tg) of the terpolymers decreased with increasing ethylene oxide (EO) content. TGA analysis indicated high thermal stability for the synthesised terpolymer.
Effects of Changing Seawater Temperature on Mechanical Properties of GRP Composites
Authors: Ray B.C.
Published: September 2018

Glass fibres were used to fabricate epoxy and unsaturated polyester laminated composites, which were then immersed in seawater. The specimens were immediately transferred from one seawater bath to another one at a different temperature to induce thermal shock, with concurrent hydrothermal ageing. Thermal shocks of two types, up-cycle (lower to higher temperature immersion) and down-cycle (higher to lower temperature immersion) were applied and their repetition induced thermal fatigue. The aged samples were subjected to 3-point short beam shear tests. The tests were performed at room temperature with 2 mm/min and 50 mm/min crosshead speeds. The weakening effects were sensitive to loading rate. The effect of fibre volume fraction was also investigated. The maximum interlaminar shear strength fell by 35% in glass/epoxy composites (in 55 and 65 weight% fibres) and by 33% in glass/polyester composites (in 60 weight% fibres) as a result of the most severe conditioning cycles. It was also observed that the reduction in shear strength in general was less at high crosshead speeds. This may have been linked to a reduction in matrix ductility.
Characterisation and Quantification of Lubricants in a Cross-Linkable Varnish by Fourier Transform Infrared Absorption Spectroscopy (FT-IR) and Differential Scanning Calorimetry
Authors: Claire Menard , Serge Alamercery , Guy Raffin , Sylvie Mac Cormack , Olivier Neel , Marie-Florence Grenier Loustalot
Published: September 2018

The lids of beverage cans are coated with varnish before stamping. In light of the considerable stress undergone by the metal during stamping, the coefficient of friction of the cross-linked coating must be optimised. To this end, the compounder can add lubricants to the varnish matrix. After heat treatment of the varnish, they contribute to the success of the stamping process.

The present work describes the use of Fourier transform infrared spectroscopy and differential scanning calorimetry to characterise these mixtures of lubricants and to assay them in situ in the varnish.
Preparation and Characterization of Montmorillonnite/Carrageen/ Guar Gum Gel Spherical Beads
Authors: Zhang Ji , Wang Wenqiang , Wang Yunpu , Zeng Jiayu , Zhang Shengtang , Lei Ziqiang , Zhao Xutao
Published: September 2018

Composite gel spherical beads of carrageen and guar gum were prepared with a size range of 2 to 3 mm, by adding montmorillonite (MMT) as a modifier for use in immobilised cell carrier technology. The interior structure and functional groups of the beads were characterised by XRD and FT-IR and the thermal stability of the beads was measured by DSC. The swelling kinetics of the composite gel spherical beads was studied. We pilot-studied living Saccharomyces cerevisiae cell immobilization and the effect of storage time on the cells' activity. The beads' thermal stability was better than those of carrageen and guar gum because of the addition of MMT. The MMT made the beads form beautiful three-dimensional reticulated structures and improved their stability. It also reduced their solidification temperature and swelling ratio. The population of Saccharomyces cerevisiae on immobilised cells was about 70% of that at the beginning and was still 107 cells/g after storage for 3 months.
Sol-Gel Synthesis and Characterisation of Nano-sized Hydroxyapatite Powders and Hydroxyapatite/ Poly(D,L-lactide-co-glycolide) Composite Scaffolds
Authors: Gu Shuying , Zhan Hui , Ren Jie , Zhou Xinyu
Published: September 2018

Nano-sized hydroxyapatite (NHA) powders were prepared from calcium nitrate Ca(NO3)2•4H2O and phosphorus pentoxide using a sol–gel approach. The effects of processing parameters on the composition granularity, and morphologies of hydroxyapatite powders were investigated by thermo-gravimetry/differential scanning calorimetry, X-ray diffraction Fourier Transform-infrared spectroscopy, laser particle analysis and transmission electron microscopy. High purity HA powders with particle size of 30–100 nm were obtained by calcining HA gel at 600 °C. The granularity had a narrow distribution and the particles were dispersed well at 600 °C. Hydroxyapatite/poly(D,L-lactide-co-glycolide) (NHA/PLGA) composite scaffolds were prepared by thermally induced phase separation. The compressive strength and water absorption of the scaffolds were investigated. Their mechanical strength increased significantly with the addition of NHA.

The composites with 25 wt.% of NHA exhibited good mechanical properties with an average compressive strength of 2.53 MPa. The hydrophilicity increased with the addition of NHA too. NHA/PLGA scaffolds could be a candidate for tissue engineering.
Semi-Continuous Shear Flow Investigation into Medium and High Molecular Weight Polyhydroxybutyrate Blends
Authors: Sharma Lakshmi , Ogino Yoshino , Kanaya Toshiji , Iwata Tadahisa , Doi Yoshiharu
Published: September 2018

We investigated the changes in morphology of medium and high molecular weight polyhydroxybutyrate blends (MMWT/HMWT PHB) during shearing, using various in-situ rheological methods. On single shearing, fibres were formed only at the highest MMWT/HMWT ratio of (97/3). This was attributed to a critical orientation molecular weight. Fibre formation took place with all compositions and there was a rapid initial shish formation on multiple shearing. This is evidence for a partial shish based on the Janeschitz–Kriegl model.
A Kinetic Model for the Low Temperature Curing of an Unsaturated Polyester Resin with Single and Dual Initiators
Authors: Vafayan Mehdi , Beheshty Mohammad Hosain , Nasiri Hasan
Published: September 2018

A kinetic model has been developed for the prediction of reaction and gel time in the curing behaviour of an unsaturated polyester resin initiated by methyl ethyl ketone peroxide (MEKP), acetylacetone peroxide (AAP) and the MEKP/AAP dual initiator system. The curing behaviour was examined by gel time and pseudo-adiabatic exotherm measurements. We demonstrated that at room temperature and for a constant concentration of promoter, the logarithm of the reaction time (t) for each conversion can be described as a linear function of the logarithm of (Io% + R), namely ln t = a - b ln (Io% + R), where Io% is the initial content (wt%) of one of initiators and R is a constant dependent on the sum of the initial initiator contents, initiator molar masses and their kinetic parameters. It was also established that there is a linear relationship of the type ln((MEKP)o%/(AAP)o%)=A+Btgel between the ratio of the initial initiator contents and the gel time when MEKP and AAP mixtures were used as dual initiator systems for room temperature curing, with a constant concentration of promoter.
Effect of Compatibiliser and Fibre Content on Jute Fibre Reinforced HDPE/EPDM: A Dynamic Mechanical and Thermal Study
Authors: Sarkhel Gautam , Banerjee Amarnath , Bhattacharya Pinaki
Published: September 2018

The thermal and dynamic mechanical properties of jute fibre reinforced high density polyethylene (HDPE)/ ethylene-propylene-diene terpolymer (EPDM) composites were studied. The fibre loading was varied between 10 and 30 wt%, and at each fibre loading, four compatibiliser doses were used. Dynamic parameters (storage flexural modulus (E'), loss flexural modulus (E”), loss factor or damping efficiency (tanδ) were determined in a resonance frequency mode. The storage modulus increased with increasing fibre content and a further increase was observed with the addition of compatibiliser. The tanδ was decreased by an increase in fibre content because of the restricted mobility of the polymer chains caused by the fibres. A marginal shifting of the transition was observed with an increase in the compatibiliser dose at constant e fibre loading. A low concentration of fibre increased the crystallinity of HDPE because it acted as a nucleating agent.
Elasto-Plastic Analysis of the Impact Performance of Woven Fabric Composites
Authors: Ryou Hansun , Kim Ji Hoon , Joo Ki Ho , Chung Kwansoo , Youn Jae Ryoun , Kang Tae Jin
Published: September 2018

The impact performance of laminated plain-woven fabric composites was analysed here using the elasto-plastic constitutive law, which can account for the anisotropic and asymmetric properties of fibre-reinforced plastics. The isotropic yield criterion was modified to account for the anisotropic and asymmetric initial yielding, while the kinematic hardening law with anisotropic evolution of back-stress was used for the anisotropic hardening behaviour. The impact tests were performed on laminated plain-woven composites. The simulation results for the impact tests compared well with experimental results.
Dynamic Viscoelasticity of Carbon Fibre Reinforced Polymers under High Load: Effects of Static and Dynamic Loads
Authors: Zuoguang Zhang , Chenghong He , Yubin Li , Zhijie Sun
Published: September 2018

The load applied on the specimen in common dynamic mechanical thermal analysis (DMTA) is of the order of several Newtons to several tens of Newtons, far lower than that in service life. In this study a dynamic mechanical thermal analyser (EPLEXOR 500, with a total load up to 500 N) was applied to investigate the effects of static load and dynamic load (sine-wave load) on the dynamic viscoelasticity of unidirectional carbon fibre reinforced epoxy resin composites. The effects of the load on the dynamic viscoelasticity of polymer matrix composites (PMCs) are expressed mainly in two ways. On the one hand, the load affects the magnitude of the dynamic viscoelastic parameters. The storage modulus increases with increasing static load and decreases with increasing dynamic load. Such variations are obviously related to the interaction between the two kinds of load. The increase in load, whether static or dynamic, can result in a decline in the loss tangent. On the other hand, there exists a frequency-temperature-load equivalence for a carbon fibre-reinforced polymer's dynamic viscoelasticity. An increase in static load raises the glass-transition temperature and pushes the frequency spectrum curve towards a low frequency, while the effects of dynamic load are the reverse.
Antimicrobial Properties of Orthopaedic Textiles after In-Situ Deposition of Silver Nanoparticles
Authors: Pohle Dirk , Damm Cornelia , Neuhof Johanna , Rösch Alfons , Münstedt Helmut
Published: September 2018

Materials exhibiting an antimicrobial effect are especially advantageous for medical textiles which are in very close and long-term contact with human skin. Orthopaedic stockings made of terry cotton and polyamide were coated with silver nanoparticles by a simple dip coating process under mild conditions. Both textiles released silver ions over at least 28 days. The silver ion release for both materials is governed by diffusion. The amount of silver ions released by the cotton textile was higher than by the nylon stockings by about a factor of 4. The reason was a larger silver reservoir in the cotton sample, because it contains much more silver than the nylon fabric. As expected from the results of the Ag+ release tests, both these silver coated textiles were active against Escherichia coli.
Mechanical Properties and Microstructures of Gfrp Rebar after Long-Term Exposure to Chemical Environments
Authors: Park Hae-Kyun , Lee Su-Jin , Kim Yoon-Jeong , Jang Chang-Il , Won Jong-Pil
Published: September 2018

This study describes accelerated degradation tests on glass fibre-reinforced polymer (GFRP) rebar to evaluate its long-term durability. The tests used simulated building acid, sulphate and de-icing environments. We measured the resulting reduction in the mechanical properties of the rebar and performed a microstructural degradation analysis of the rebar. The acidic environment consisted of a 0.6% acetic acid solution at a pH of 2.92, whereas the sulphate environment contained 3% sodium sulphate solution, and the de-icing environment was composed of 4% calcium chloride solution.

Tensile strength tests were performed to measure the mechanical properties of the rebar after it was immersion in one of the environments for 50 to 100 days. We also measured the change in the internal pore distribution and in the shape of the rebar surface morphology using mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) technology to observe the microstructure degradation. The tests demonstrated that GFRP rebar exposed to degradation environments exhibited only slight reductions in mechanical properties with time. Areas of surface degradation were difficult to observe in the SEM analysis, and the MIP pore values were very small, indicating a dense structure. Since the durability of GFRP rebar was not adversely affected to an appreciable degree by exposure to the degradation environments, it was deemed suitable for use in concrete reinforcements.
Curing Behaviour of Epoxy Resin with a Diamine Containing Heterocyclic Rings
Authors: Lu X.D. , Huang Y.D. , Zhang C.H.
Published: September 2018

The curing behaviour of a new epoxy curing agent, 2, 6-di (p-aminophenyl) benzo[1.2.5.4] bisoxazole (DIABO) was discussed. Diglycidyl-4, 5-epoxycyclohexane -1,2-dicarboxylate (TDE) was cured with a mixture of DIABO and diaminodiphenylsulfone (DDS). The aspects investigated including the curing procedure, reaction kinetics parameters and the heat resistance of the product. Average apparent activation energy of the resin's curing reaction was 63.55 kJ/mol, calculated according to the Kissinger and the Ozawa methods. The glass transition temperature was 261 °C and 257 °C determined by torsional braid analysis (TBA) and differential scanning calorimetry (DSC) respectively. The integral procedural decomposition temperature (IPDT) was 814 °C, respectively. Char residue was 44.58% at 572 °C. Compared to cure with TDE/DDS, these properties were improved by 18%, 8%, 30% and 50%, respectively.
Impact of Processing Parameters and Tapering of Injection Chamber Walls in Resin Injection Pultrusion
Authors: Jeswani A.L. , Roux J.A.
Published: September 2018

This study seeks to improve the wet-out and thus the quality of the pultruded part in the tapered injection pultrusion process. Complete wet-out of the dry fibre reinforcement by the liquid resin depends strongly on the processing parameters. Process parameters modelled were: fibre pull speed, fibre volume fraction and resin viscosity. In this work a 3-D finite volume technique was developed to simulate the flow of polyester resin through the glass rovings. The results show the impact of the tapering of the injection chamber walls on the minimum injection pressure necessary to achieve complete fibre matrix wet-out and the resin pressure at the injection chamber exit. Important chamber design information is presented.
Effect of Pc-Oligomer on Structure and Properties of Pc/Abs Injection Mouldings
Authors: Umemura T. , Takashima S. , Kotaki M. , Hamada H.
Published: September 2018

The effects of PC-oligomer addition on the internal morphology and mechanical properties of injection mouldings of polycarbonate (PC)/Acrylonitrilebutadiene-styrene (ABS) blends were investigated. Incorporating PC-oligomer into PC/ABS blends caused a significant improvement in strain at break under tensile loading without sacrificing tensile modulus and strength. Highly elongated ABS phases along the flow direction were observed in the blend with PC-oligomer.
Uv-Resistant Performance of Polystyrene/Tio2 Composite Particles Containing Organic UV-stabiliser Groups
Authors: Zou Jiangpeng , Zhao Yi , Yang MingJiao , Dan Yi
Published: September 2018

Polystyrene/TiO2 composite particles containing organic UV-stabiliser groups (i.e. poly[styrene-co-sodium sulfopropyl lauryl maleate-co-2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone] [poly(St-co-M12-co-BPMA)]/TiO2 composite particles) were prepared. Ultraviolet-visible absorption spectroscopy, UV-vis diffuse reflectance spectroscopy, differential scanning calorimetry, weight loss and gel permeating chromatography measurements were used to study their UV resistant performance. The results indicate that the UV-absorbing ability of the poly(St-co-M12-co-BPMA) grafted onto the surface of TiO2 was enhanced by an increase in BPMA content, and the poly(St-co-M12-co-BPMA)/TiO2 composite particles could absorb more than 90% of UV light in the 210–400 nm wavelength. The ultraviolet absorption capacity of poly(St-co-M12-co-BPMA) grafted onto the surface of TiO2 did not change between 240–280 nm after UV irradiation for 500 h but that of polystyrene increased considerably. The weight loss of the composite particles was much lower than that of polystyrene after UV irradiation, but the glass transition temperature of the composite particles did not change after UV irradiation for 500 h whereas that of polystyrene changed a lot. The molecular weight of poly(St-co-M12-co-BPMA) grafted from the surface of the TiO2 particles was higher than that of the pure poly(St-co-M12-co-BPMA), and the molecular weight of the grafted poly(St-co-M12-co-BPMA) changed little after UV irradiation. These results show that the UV-resistant performance of polystyrene can be enhanced by introducing the organic UV-stabiliser BPMA and the inorganic UV-stabiliser titanium dioxide into the polystyrene chains by covalent bonding.
Determination of Wrinkling Criteria for an Incompressible Polymer Membrane by Non-Linear Elastic Finite Element Method
Authors: Kim Ji Hoon , Lee Myoung-Gyu , Han C.-S.
Published: September 2018

A wrinkling criterion for non-linear elastic membrane materials such as thin polymer, fabric or rubber structures has been determined by employing finite element analysis as an alternative to the difficult experimental counterpart. The hyperelastic constitutive equation proposed by Ogden was implemented into the commercial finite element program ABAQUS with user material subroutine VUMAT. The relation between strain energy and the principal values of the stretch tensor was obtained in order to trace the wrinkle/non-wrinkle boundaries. It was shown that the wrinkling of an elastic membrane can be regarded as being initiated at the instance of abrupt slope change of the strain energy-stretch curve, which was verified by comparing the criterion obtained by finite element analysis with the existing analytical solution.