bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Colloidal Silica on Adhesion of Glass Fibres to Polypropylene
Authors: Chou Shen , Lin Ling-Shiou
Published: September 2018

Colloidal silica was used to treat glass fibres to improve their adhesion to polypropylene resin (PP). The glass fibres were also treated with a coupling agent and maleic anhydride modified polypropylene emulsion (MAPP) to enhance their interfacial bonding. The surfaces of the glass fibres were observed by scanning electron microscopy (SEM).

Because colloidal silica made the surfaces of the glass fibres rougher, PP could anchor on the surface of glass fibres to improve the fibre/PP bonding. These results were proved by using a microbonding pull-out test. The composites of glass fibres and PP were fabricated by means of a twin screw extruder and an injection moulding machine. The tensile strength and flexural strength were determined and the fracture surfaces were observed by SEM to establish the contribution of the surface treatment.

The test results demonstrate that the tensile strength of the composites reinforced by those glass fibres treated with colloidal silica first and then with coupling agent and MAPP was 73.4% higher than that of composites reinforced with untreated glass fibres, and 24.0% higher than that of composites without colloidal silica but still treated with coupling agent and MAPP. As for the flexural strength, the colloidal silica, coupling agent and MAPP-treated composite was 75.9% stronger than the untreated ones and 22.3% stronger than materials without colloidal silica but treated with both coupling agent and MAPP.
Dynamic Viscoelastic Properties of Long Organic Fibre Reinforced Polypropylene in Molten State
Authors: Nishitani Yosuke , Sekiguchi Isamu , Hausnerova Berenika , Nagatsuka Yoshihiro , Kitano Takeshi
Published: September 2018

This paper deals with the dynamic viscoelastic properties of long organic fibre (aramid fibre (KF), polyvinyl alcohol fibre (VF) and polyamide fibre (PA6)) reinforced polypropylene in the molten state. Long organic fibres mixed with polypropylene fibres by an apparatus called a “fibre separating and flying machine″ were compression moulded into 3mm thick composites. Dynamic viscoelastic properties of these composites were measured in the molten state using a rotational parallel plate rheometer. It was found that the dependence of angular frequency on storage modulus, G′, for long organic fibre reinforced polypropylene is different from that of volume fraction of fibre, Vf and the relationships depend on the characteristics of the reinforcing organic fibres. The slope of the dynamic viscosity, η′ vs. angular frequency, ω curves increases gradually up to 45 degrees with increasing Vf. Influence of fibre content on dynamic viscoelastic properties depends on the organic fibre used. For low fibre content, G′ increases with increasing Vf in the same way as η′. However, the opposite trend is observed for high fibre content composites. It can be deduced that there is an apparent yield from the relations between complex viscosity, η* and complex modulus, G*. The yield value, G*y increases gradually with increasing fibre content and approaches a fixed value. All of the long organic fibre reinforced polypropylenes studied here are more sensitive to temperature than inorganic fibre reinforced composites.
Rheological and Mechanical Properties of Gum and Filled Blends of Acrylate Rubber and Fluororubber
Authors: Kader M. Abdul , Bhattacharyya Asish K. , Bhowmick Anil K.
Published: September 2018

Rheological, mechanical and dynamic mechanical thermal properties of gum and filled acrylate rubber (ACM), fluoro rubber (FKM) and their blends were studied. The systems exhibited pseudo plastic flow behaviour. The shear viscosity of the blends decreased with higher concentration of ACM. There was little effect of temperature on the viscosity of the blends at different shear rates. Addition of filler to the 50/50 (w/w) ACM/FKM blend increased the shear viscosity. The equilibrium die swell decreased with increasing loading of carbon black and was affected by the filler type. A linear generalized relationship was obtained between die swell and maximum recoverable deformation. The activation energy of the melt flow process decreased with an increase in shear rate for all the gum and filled systems except neat ACM, where there was a slight increase in activation energy. The mechanical properties of the filled compounds improved linearly with filler loading. Tan δ peak temperature did not change with filler loading although the values of tan δmaximum decreased. The storage modulus of the blends increased with increasing filler loading, indicating the presence of polymer filler interactions.
Epoxy Based Thermal Stabilizer for Poly(Vinylchloride)
Authors: Patel Pritesh G. , Patel Girish R. , Parmar Jayant S
Published: September 2018

A tetrafunctional epoxy resin was prepared and characterized by epoxy equivalent weight, percentage nitrogen, IR spectroscopy and number average molecular weight (Mn) determined by GPC. The resin was evaluated as a thermal stabilizer for polyvinylchloride (PVC). The stabilizing efficiency was tested by yellowness index, HCl liberation, UV absorption, induction time, and changes in mechanical properties (tensile strength, elongation at break and Shore-A hardness). Epoxy resins with several epoxy groups are effective as in stabilizing PVC against dehydrochlorination during processing and use, compared with tribasic lead sulphate. The replacement of lead based stabilizers by epoxy stabilizers will remove the toxic effect of lead in water flowing through PVC pipes.
Poly(Butylene Succinate) Composites Reinforced with Short Sisal Fibres
Authors: Shibata Mitsuhiro , Makino Retsu , Yosomiya Ryutoku , Takeishi Hiroyuku
Published: September 2018

Poly(butylene succinate) composites reinforced with short sisal fibre were prepared by melt mixing and subsequent injection moulding. The influence of fibre length, fibre content and the surface treatment of the natural fibres on the mechanical properties of the composites were evaluated. Regarding fibre length, the tensile and flexural properties of the composites had maxima at a fibre length of about 5 mm. The flexural and tensile moduli of the composites increased with increasing fibre content. Although the tensile strength hardly changed, the flexural strength increased up to a fibre content of 10 wt%. The dynamic mechanical analysis of the composites showed that the storage moduli at above ca.-16°C (corresponding to the glass transition temperature of the matrix) increased with increasing fibre content.
Effect of Chemical Oxidation on the Interfacial Bonding between Carbon Fibre and Epoxy Resin
Authors: Lin Jeng-Shyong , Huang Ye-Houn , Chiu Hsien-Tang
Published: September 2018

Polypyrrole (PPy) was deposited on carbon fibres via the oxidation-polymerization of pyrrole (Py) with ferric ions. These PPy-deposited carbon fibres were then made into composite boards with epoxy resin. The interfacial bonding between carbon fibre and epoxy resin was evaluated by measuring the interlaminar shear strength (ILSS), tensile strength before and after impact (TAI), and flexural strength. Experimental results show that deposition of PPy can improve the ILSS, tensile strength, and flexural strength. Furthermore, TAI is also reduced by the deposition of PPy. The interfacial bonding was the highest when the carbon fibre was immersed in 20 wt% FeCl3(aq) and then reacted with 0.5 M Py in acetonitrile for 20 min.
Vibration Reduction Ability of Polymers, Particularly Polymethylmethacrylate and Polytetrafluoroethylene
Authors: Fu Wenhai , Chung D.D.L.
Published: September 2018

The vibration reduction ability of thermoplastics (PMMA, PTFE, PA-66 and acetal) and of a thermoset (epoxy) was compared by dynamic flexural testing at ≤ 1.0 Hz. Among these polymers, PMMA exhibited the highest loss modulus, while PTFE exhibited the highest loss tangent. A synthetic rubber had an exceptionally low loss modulus, but an exceptionally high loss tangent. Epoxy and acetal exhibited the lowest loss tangent.
An Analysis of Microdroplet Test: Effects of Specimen Geometry, Matrix Type, Fibre Treatment and Water Ageing
Authors: Hodzic A. , Stachurski Z. H. , Kim J. K.
Published: September 2018

The microdroplet test has been used to characterize the interfacial bond in fibrous composite materials. The specimen consists of a length of fibre with a drop of resin cured on it and pulled out while the drop is being supported by a platinum disc with a hole. A properly tested specimen fails at the droplet's tip-fibre interface, revealing the ultimate interfacial shear strength. The microdroplet test is carried out under optimal testing conditions, established from our previous work, in order to obtain fully debonded specimens for the interfacial shear stress analysis of the fibre-matrix bond. Three thermosetting resins are applied on silane coated and acetone washed (silane removed) glass fibres in order to investigate the influence of the silane coupling agent on the fibre-matrix bond. Also, these systems were aged in water at room temperature for periods of 3, 6 and 10 weeks and the influence of water degradation on the fibre-matrix bond is investigated for both groups of glass fibres (silane coated and acetone washed). The group of glass fibres washed in acetone produced weaker fibre-matrix bond and accelerated water degradation of the interfacial bond. It is found that the influences of two dominant geometric parameters (conus angle and droplet length) on the test results are reciprocally opposite, generating scatter in the experimental results. It is shown in this work that the microdroplet test can be used as a reliable tool for measurement of the fibre-matrix adhesion.
Effect of Methacrylic Acid on the Mechanical Properties of Peroxide-Cured Sbr Vulcanizates Filled with Al(Oh)3
Authors: Yin Dehui , Zhang Yong , Zhang Yinxi , Peng Zonglin
Published: September 2018

Methacrylic acid (MAA) was used as an additive for the modification of peroxide-cured styrene-butadiene rubber (SBR) highly filled with Al(OH)3 filler. The experimental results show that the introduction of MAA can improve the mechanical properties of the SBR vulcanizates to a great extent and that the mechanical properties of the SBR vulcanizates depend greatly on the MAA and Al(OH)3 contents. At the Al(OH)3 content of 150phr, the hardness, modulus, tensile strength and tear strength of the SBR vulcanizates increase with increase in the MAA content. When the MAA content is 40 phr, the tensile strength, elongation at break and tear strength of the SBR vulcanizates are 15.7 MPa, 212%, and 38.7 kN/m, respectively. The oxygen index of the SBR vulcanizates depends on the Al(OH)3 content and is less affected by the MAA content. The SBR vulcanizates have good thermal aging-resistance. Scanning electron microscope (SEM) study reveals the changes in the fractured surfaces of the Al(OH)3 filled SBR vulcanizates after using MAA, which is related to the changes in the mechanical properties.
Antioxidants as Sources of Plastics Discoloration: Structural Effects
Authors: Pospíšil J. , Habicher W. D. , Zweifel H. , Pilař J. , Nešpůrek S. , Piringer O. G.
Published: September 2018

Sacrificial transformation (consumption) of antioxidants is an inevitable consequence of their active role in the protection of plastics from oxidation. The process results in various new products with conjugated double bonds, some of them being responsible for plastics discoloration. Structures of principal colorants arising from phenolic and aromatic amine antioxidants and phenolic UV absorbers are outlined.
Neoalkoxy Titanate and Zirconate Coupling Agent Additives in Thermoplastics
Authors: Monte Salvatore J.
Published: September 2018

Ti or Zr coupling agents chemically bridge two dissimilar species such as an inorganic filler/particulate and organic polymer via proton coordination on non-silane reactive substrates such as CaCO3 and carbon black without the need of water of condensation as with silanes. Minor amounts of thermally stable neoalkoxy titanate and zirconate additives provide a means for post reactor, in-situ metallocene-like repolymerization catalysis of a filled or unfilled polymer during the plastication phase resulting in: significantly faster thermoplastic processing at lower temperatures; lower polymer recrystallization time; and the copolymerization of dissimilar polymers. Examples: both 40% CaCO3 filled and unfilled PP compounds experienced respective reductions of 35.5% and 42% in injection mold cycle time and 22% and 11% in process temperature; 17% “pyrophosphato titanate coupled conductive carbon black (CB)” in LDPE provides the same Positive Temperature Coefficient effect as 25% untreated CB; a 39.7% reduction in the recrystallization time of PPS; a ten-fold increase in the elongation of a PET/PC regrind alloy; and the regeneration of recycled blends of LDPE and PP regrinds. The catalysis effect is shown to be permanent and recyclable. Coupling agent liquid, powder and pellet forms; dosage; data and applications methodology in compounding, injection and blow molding are discussed. New and novel transparent and permanent antistatic agents based on the formation of bipolar layers of dissimilar trineoalkoxy zirconates are shown to be non-blooming, non-moisture dependent providing volume as well as surface ESD effects.
On the Effects of Fiber Length and Spatial Distribution on the Stiffness of Short-Fiber Reinforced Composites
Authors: Juhlin Erik , Chen X. , Papathanasiou T. D.
Published: September 2018

We report on the results of a computational investigation of the effect of fiber aspect ratio (ar) on the stiffness of composite rods reinforced with rigid spheroidal inclusions. The reinforcing spheroids are randomly placed within the containing rod and are also perfectly aligned with the tensile axis. Attention is focused in the interesting region of low (ar), where the stiffness of the composite rod is known to be most sensitive on (ar). Use of low aspect ratio fibers makes the results of this analysis suitable for a class of processed materials, such as whisker-reinforced metal-matrix composites and extruded or molded short-fiber-reinforced polymers. We consider steady-state three-dimensional deformations of composite rods containing up to 50 individual, randomly placed aligned spheroids. The equations of elasticity for the entire multi-fiber assembly are solved using the Boundary Element Method (BEM), implemented on a four-processor server and the force needed to impose a certain tensile deformation on the composite is computed. From this, an effective tensile modulus is obtained. Statistical averages of the computed effective moduli are compared to the predictions of the Mori-Tanaka model for the stiffness of short fiber composites. We find a good agreement at low values of (ar). Additionally, we investigate the effect on stiffness of random perturbations in fiber length around a mean value.
Phenolic Resins – Characterizations and Kinetic Studies of Different Resols Prepared with Different Catalysts and Formaldehyde/Phenol Ratios (I)
Authors: Bouajila J. , Raffin G. , Waton H. , Sanglar C. , Païsse J.O. , Grenier-Loustalot M.F.
Published: September 2018

The physicochemical and kinetic properties of resols prepared with different catalysts (NaOH, LiOH and Ba(OH)2) and variable formaldehyde/phenol ratios (2.5 £ R £ 3.5) were followed to determine their effects on the mechanisms and reaction products at a fixed pH and temperature.

Kinetic monitoring and quantification of residual monomers were carried out by liquid chromatography coupled with mass spectrometry (LC/UV/MS), by 13C nuclear magnetic resonance (NMR) and by chemical assay for formaldehyde. Oligomer formation (n ≥ 2) was determined by LC/UV/MS, size exclusion chromatography (SEC) and 13C NMR. It was found that minor compounds form during syntheses (phenol methanol hemiacetals, hemiacetals of phenol and of oligomers…) and that the ratio R affects primarily the kinetics of formation of monomers and oligomers, in contrast to the catalysts that modify reaction mechanisms. The understanding of the structure of the resols was an important step for the determination of the final properties of the material.
Radiation Induced Graft Copolymerization of Methyl Acrylate and Ethyl Acrylate onto Poly(tetrafluoroethylene-co-ethylene) Film
Authors: Kaur Inderjeet , Misra B. N. , Kumar Raj , Singh Baljit
Published: September 2018

To introduce functional moieties into Tefzel® film, a copolymer of tetrafluoroethylene and ethylene, graft copolymerization of vinyl monomers such as methyl acrylate (MA) and ethyl acrylate (EA) was attempted by a pre-irradiation method in aqueous medium. Optimum conditions for obtaining the maximum grafting was evaluated for both monomers. Maximum grafting of MA (306.0%) and EA (462.1%) was obtained at a total dose of 25.4 and 31.9kGy respectively, using [MA] = 2.20 mol/L and [EA] 0.032 moles. The effect of aliphatic alcohols of varying chain length, such as methanol, ethanol, n-butanol, 1-Pentanol and cyclohexanol on the percentage grafting of MA & EA was also studied. Characterization of Tefzel® and grafted Tefzel® films was carried out by IR spectroscopy and thermogravimetric analysis. Grafted Tefzel® film was found to have improved thermal resistance.
Enhanced Performance of LDPE/SBS Blend Modified Asphalt through Dynamic Vulcanization
Authors: Gao Guangtao , Zhang Yong , Zhang Yinxi , Sun Kang
Published: September 2018

A blend of a Low-Density Polyethylene (LDPE) and a Styrene-Butadiene-Styrene triblock copolymer (SBS) was mixed with an asphalt, and a storage-stable modified asphalt was prepared by dynamic vulcanization. The vulcanization characteristics of this LDPE/SBS blend-modified asphalt were studied using a strain-controlled rheometer. The vulcanization of the SBS in the blend-modified asphalt resulted in a marked increase in the torque. In addition, the physical properties of the LDPE/SBS blend-modified asphalt containing even a small quantity of sulfur were improved compared to the modified asphalt without sulfur. The storage stability of the LDPE/SBS blend-modified asphalt was also improved by the addition of sulfur. The rheological properties of the LDPE/SBS blend-modified asphalt before and after adding sulfur were characterized using a dynamic shear rheometer and a rotational viscometer.
In-plane Shear Measurements of Textile Composites with Large Unit Cells using the Plate Twist Test
Authors: Weissenbach G. , Brown D. , Limmer L.
Published: September 2018

The application of the plate twist test method to 3D-woven textile composites was investigated using both numerical analyses of the test set-up as well as experimental results. Comparisons with the widely used V-notched beam shear and 10°-off-axis tension tests are introduced in an attempt to identify the true in-plane shear response. The results of this study demonstrate that with careful specimen preparation and an adequate test fixture precise in-plane shear modulus data can be obtained. Moreover, for 3D-woven textile composites with their large unit cells the plate twist test appears to be superior in revealing the “true” in-plane shear behaviour.
Effect of Punching Density on the Mechanical and Thermal Properties of Needle-punched Nonwoven Carbon/Phenolic Composites
Authors: Kang Tae Jin , Jung Kyung Ho , Park Jong Kyoo , Youn Jae Ryoun , Lee Seung Goo
Published: September 2018

The effects of changes in the fibre orientation on the mechanical properties of nonwoven composites were investigated through 3-point bending, short beam shear and tensile tests. Oxidized polyacrylonitrile(PAN) carded webs were needle-punched, and then carbonized to fabricate carbon composites with phenolic resin. The interlaminar shear, tensile and flexural strengths increased with increasing punching density. However, the rate of increase reduced and interlaminar shear and tensile strengths decreased with excessive punching density. The erosion rate and the insulation index were calculated by means of a torch test. The ablation resistance increased with increasing punching density, but no significant increase in the erosion rate with increasing punching density above 477 penetrations per square centimetre was found. The thermal conductivity of needle-punched nonwoven carbon/phenolic composites increased with increasing punching density.
Mechanical Properties of Nanocomposites from Ball Milling Grafted Nano-Silica/Polypropylene Block Copolymer
Authors: Ruan Wen Hong , Zhang Ming Qiu , Rong Min Zhi , Friedrich Klaus
Published: September 2018

Nanocomposites consisting of ethylene-propylene block copolymer filled with nano-silica (pre-treated by ball milling aided graft polymerisation) were prepared by a conventional compounding technique. The mechanical performance of the nanocomposites and the morphological changes induced by the addition of the nanoparticles were investigated. It was confirmed that the copolymer chains were chemically bonded to the silica particles during mechanochemical grafting in the ball mill. Morphology observations revealed that strong interfacial interaction between the grafting polymer (i.e., poly(butyl acrylate)) and the matrix (i.e., ethylene-propylene block copolymer) is critical for bringing the reinforcing effect of the nanoparticles into play. Owing to the enhanced interfacial interaction, the grafted nanoparticles exhibited a nucleating effect and improved the crystallinity of the polymer matrix. In addition, the particles also had a toughening effect on the amorphous polypropylene phase because of entanglements between the grafting polymer and the matrix. Insufficient interaction between the nanoparticles and ethylene-propylene rubber phase of the copolymer matrix actually introduces restraints. As a result, the tensile strength and modulus of the nanocomposites can be significantly increased by using low loadings of the treated nanoparticles. The decrease in the notched Charpy impact strength was insignificant in comparison to that of conventional micron-scale inorganic particles filled composites. The technical route proposed is therefore feasible for fabricating polymer composites with inorganic nanoparticles.
Non-linear Viscoelastic and Physical Ageing Characterisation of Thermoset PR-500 Epoxy Resin
Authors: Gupta V. , Roy S. , Dharani L. R.
Published: September 2018

It is now well known that because of their polymeric matrices (and sometimes their use of viscoelastic fibres) structural polymer composites can exhibit creep or stress relaxation behaviour, leading to delayed failure long after the initial design and fabrication process. In addition, these time-dependent viscoelastic properties are significantly influenced by the sub-T physical ageing of these materials. Therefore any durability study of polymer composites for elevated use-temperature applications should address both the nonlinear viscoelastic response and the physical ageing effect of the constituents. The material nonlinearity in the resin has a ‘softening’ effect whereas physical ageing causes polymers to become stiffer and more brittle with age, increasing the likelihood of the more rapid progression of various damage states. Therefore, coupled material nonlinear and physical ageing conditions should be analysed to predict which effect would dominate under the applied loads and duration of loading.

The primary objective of this paper is to present an experimental investigation of the nonlinear viscoelastic response of the PR500 resin at various stress levels. Also, the physical ageing characterisation results for a set of temperature and stress conditions are summarised. The properties summarised were successfully used in a multi-scale micro-mechanical methodology1, to study the AS4/PR500 five-harness satin woven-fibre composite laminate. PR500 is the polymer matrix that was modelled using the data presented here.
Temperature Effects on the Fatigue Behavior of Foam Core Sandwich Structures
Authors: Kanny Krishnan , Mahfuz Hassan , Thomas Tonnia , Jeelani Shaik
Published: September 2018

The effects of temperature on the fatigue behavior of foam core sandwich structures have been investigated. Two types of PVC cores of the same nominal density were used; one was linear HD foam and the other a slightly cross-linked H foam. In both cases the face sheet material was S2-glass/vinylester. Fatigue tests were conducted on these sandwich structures at room temperature (RT), 40° and 80 °C. The tests were conducted on an MTS machine equipped with an environmental chamber. The stress ratio was set at R=0.1 and the frequency, f=3Hz. S-N diagrams were generated and revealed that fatigue life increased with decreased stress and decreased with increased temperatures. At RT, HD structures revealed much longer fatigue life compared to H structures however at elevated temperatures, a complete reversal of this trend was seen. Further, significant differences in the failure between H and HD structures were observed. Details of the experimentation, the analysis of the fatigue data, and damage mechanisms are presented.
Durability of CFRP Adhesive Joints in Hot Water
Authors: Kuriyama Takashi , Mizoguchi Machiko , Mori Hironobu
Published: September 2018

The degradation behaviour of adhesive joints in carbon fibre reinforced epoxy resin in hot water was determined by weight measurements, three point bending tests, and mode I fracture toughness tests. The crack path changed with exposure time, and the crack tended to propagate along the interface in degraded specimens because of interfacial degradation. This resulted in a change to the crack path in adhesive joint specimens from adhesive layer to laminated layer. Moreover, it may be possible to distinguish between interface and resin crack propagation in carbon fibre reinforced plastics.
Transport Characteristics of Filled Poly(ethylene-co-vinyl acetate) Membranes
Authors: Dasan K. Priya , Haseena A.P , Unnikrishnan G. , Alex Rosamma , Purushothaman E.
Published: September 2018

The effect of carbon black fillers on the solvent transport behaviour of ethylene-co-vinyl acetate (EVA) was studied using petrol, diesel and kerosene as probe molecules. Semi-reinforcing furnace (SRF), high abrasion furnace (HAF) and intermediate super-abrasion furnace (ISAF) blacks were used for the reinforcement of the matrix. EVA filled with SRF showed the highest solvent uptake, followed by HAF and then ISAF. The observations have been correlated with the morphology of the systems, as attested by scanning electron micrographs and interpreted on the basis of the particle size of the reinforcement, and also in terms of the bound rubber content. The molar mass between crosslinks has been calculated from the sorption data. Arrhenius activation parameters for the process of diffusion and permeation and thermodynamic quantities such as enthalpy and entropy were also determined. The first order equation was used to study the sorption kinetics. The mechanism of transport was found to deviate slightly from the regular Fickian trend, observed with conventional rubbers. A sorption (S)-desorption (D)-resorption (RS)-redesorption (RD) experiment was carried out to study the structural changes occurring in the filled matrix during solvent transport.
Comparative Rheological Properties of Dope Solutions of High Molar-Mass Poly(acrylonitrile-co-itaconic acid) and Poly(acrylonitrile-co-methylacrylate-co-itaconic acid)
Authors: Devasia Renjith , Nair C.P. Reghunadhan , Ninan K.N.
Published: September 2018

The rheological behaviour of a dope solution of poly(acrylonitrile-co-itaconic acid) copolymer was compared with that of a poly(acrylonitrile-co-methylacrylate-co-itaconic acid) terpolymer of identical molecular weight. The effects of temperature, concentration and shear force on the rheology of the polymer dope were examined. In both cases, the temperature dependence of zero shear viscosity conformed to the Arrhenius-Frenkel-Eyring equation. The free energy change ΔGv increased with concentration more significantly for the copolymer than the terpolymer. The Power Law model was fitted to the shear dependency of the viscosity, and the pseudoplasticity index (n) decreased with the dope concentration. The shear thinning behaviour was more pronounced for the terpolymer than the copolymer. The decreasing trend of the pseudoplasticity index with concentration and temperature was more pronounced in the case of the terpolymer than the copolymer. Empirical models were arrived at, which could predict the n value of the polymers of a given viscosity-average molecular weight at any concentration and temperature. The onset of shear thinning shifted to a lower shear regime with increase in solid concentration.
Polyurethane/Polyolefin Blends: Morphology, Compatibilization and Mechanical Properties
Authors: Wang Jia Sheng , Chen Xu Dong , Zhang Ming Qiu , Rong Min Zhi
Published: September 2018

The objective of this article is to review progress in the study and development of thermoplastic polyurethane (TPU)/polyolefin (PO) blends, a series of thermoplastic elastomers having the advantage of easy regulation of mechanical properties within a wide range. Important aspects including coalescence behaviour, compatibilizer species and compatilization mechanisms are discussed. The effects of interfacial interactions, surface free energy of the blend components, viscoelasticity and concentration of the dispersed phase, and mixing conditions are summarized and analyzed. Emphasis is placed on recent trends to produce stable TPU/PO blends with specific properties that are not available in either the single component of the blends or other polymers.
Release Behaviour of Bovine Serum Albumin in Syndiotactic Poly(vinyl alcohol) Hydrogel, Prepared by Freezing-Thawing
Authors: Lyoo Won Seok , Shin Dong Soo , Han Sung Soo , Noh Seok Kyun , Kim Jung Ae , Choi Han Gon , Yong Chul Soon , Kim Jae-Ryong , Kim Jung Hye
Published: September 2018

To precisely identify the effect of molecular parameters such as stereoregularity, degree of saponification (DS), and molecular weight of syndiotacticity-rich poly(vinyl alcohol) (s-PVA) hydrogels prepared by freezing-thawing on the release behaviour of bovine serum albumin (BSA), we prepared various (s-PVA)s by copolymerization of vinyl pivalate and vinyl acetate and subsequent saponification. A series of experiments showed that molecular and processing parameters of s-PVA hydrogel had a significant influence on the BSA release behaviour of the hydrogel. That is, both the release rate and the amount of residual BSA decreased with increasing syndiotacticity of PVA. In the case of s-PVA hydrogels with higher DS and higher molecular weight, the BSA release was suppressed. The rate of BSA release increased with an increase in the release temperature. In addition, the release rate of s-PVA hydrogel made with one freezing-thawing cycle was higher than with three cycles. It was confirmed conclusively that s-PVA hydrogels having various kinds of release behaviour can be prepared by controlling molecular and processing parameters of PVA, for various biomedical applications.
Effects of Injection Pressure in Resin Transfer Moulding (RTM) of Woven Carbon Fibre/Epoxy Composites
Authors: Kaynak Cevdet , Kas Y. Onur
Published: September 2018

RTM (Resin Transfer Moulding) is a closed mould process in which matrix resin is injected into a mould filled with a fibre preform. There are many RTM process parameters influencing the quality of the final product. The objective of this work was to study resin injection pressure. For this purpose, an amine curing epoxy resin was injected, using a small laboratory size RTM machine, into a flat mould filled with woven carbon fibre layers. Five different resin injection pressure levels; 1, 2, 3, 4, and 5 atm (101, 203, 304, 405, and 506 kPa) were used to produce composite sample plates. Specimens for mechanical testing and microscopic examination were extracted from various parts of the plates.

Generally, it was observed that an injection pressure level of 2 atm (203 kPa) resulted in the best mechanical performance in the specimens, mainly due to better fibre impregnation by the uniform resin flow, minimising void formation. Increasing the resin injection pressure level above 2 atm (203 kPa) resulted in differences between “macroflow” (around fibre bundles) and “microflow” (through the fibres) leading to non-uniform resin flow and void formation, hence a reduction in the mechanical properties.
Synthesis and Manufacture of Polyamide-imide/Copper Foil Laminates without Adhesive
Authors: Huang Meng-Shun , Yang Ming-Chien , Chou Shen
Published: September 2018

Three kinds of polyamide-imide (PAI) were synthesized. The polyimide prepolymer was synthesized from 4,4'-diphenylmethane diisocyanate (MDI) and 3,3'-4,4'-benzophenone tetracarboxylic dianhydride (BTDA), after which the prepolymer was reacted respectively with terephthalic acid (TPA), isophthalic acid (IPA), and 4,4'-oxybisbenzonic acid (OBBA) to form PAI-1, PAI-2, and PAI-3. Their chemical structures were characterized using elemental analyses (EA), Fourier transform infrared spectrometry (FTIR), and nuclear magnetic resonance (NMR). The thermal properties, electrical properties, solubility, and mechanical properties of these PAIs, and the peel strength retention and electrical properties of PAI/Cu laminates were measured. The dielectric constants of PAI laminates were lower than 5.5 and the dissipation factors were lower than 0.035, and were in the order of PAI-3 < PAI-1 < PAI-2. These PAI/Cu laminates exhibited peel strength higher than 2.30 kN/m under normal circumstances and higher than 2.15 kN/m after heating. The order of peel strength was PAI-1 > PAI-3 > PAI-2.
Quasi-Static Perforation Study Using a Sharp-Tip Conical Indenter on GRP Plates Containing Sand Filler
Authors: Sabet A.R. , Beheshty M.H. , Rahimi H.
Published: September 2018

The penetration and perforation performance of glass-reinforced plastic (GRP) plates containing 20% sand filler has been investigated via quasi-static indentation tests using a sharp-tip (30°) indenter. Two sizes of sand filler (75 and 600 μm) were incorporated in the composite plates to investigate the sensitivity of filler size towards loading system. Also, composite plates were subjected to perforation tests at 5 and 500 mm/min load rates. The investigation successfully used load–displacement behaviours during penetration and perforation by the sharp-tip indenter as a measure for assessing the low-velocity impact performance. The results indicated the clear role played by coarse-sized sand filler as a secondary reinforcement in terms of higher energy absorption. The residual frictional load was up to 45% of maximum perforation load, a considerable gain also due to sand filler incorporation. Composite plates containing coarse-sized filler showed higher energy absorption compared with fine-sized fillers. Higher energy absorption was obtained for plates under high loading rate (500 mm/min). Fibre and matrix fracture constituted the major damage mode in the composite plates tested, followed by delamination. The test results also showed diminishing effectiveness associated with the specific energy absorption of these plates.
Preparation and Properties of a Fragrant Acrylonitrile–Butadiene–Styrene/Polycarbonate Alloy
Authors: Liu Xiaolin , Huang Yajiang , Yang Qi , Jiang Zhiqiang , Feng Decai
Published: September 2018

The purpose of the present work was to upgrade the functionality and applicability of acrylonitrile–butadiene–styrene copolymer (ABS)/polycarbonate (PC) alloys by means of a simple blending technique. A fragrant ABS/PC alloy was prepared by adding a fragrance to the ABS/PC matrix. By tests of volatility, mechanical properties, and processing fluidity and by SEM measurements it was found that the essence not only endowed ABS/PC alloy with fragrance but also acted as a lubricant and surface treatment agent during processing. With increasing fragrant masterbatch content, the impact strength and rate of elongation at break decreased and the processing properties improved, while the yield strength remained almost unchanged. The dosage of fragrant masterbatch needed to be kept under 5 phr (parts per hundred parts resin by weight) to obtain the best combination of properties of the fragrant ABS/PC alloy. In addition, the volatility of the essence was greatly affected by the nature of the essence, the ambient temperature, and the polymer matrix. The experimental results show that the fragrance of the ABS/PC alloy can be maintained for a long time at room temperature.
Evaluation of the Morphology and Performance of Polyether Sulfone Reverse Osmosis Composite and Non-composite Membranes
Authors: Madaeni S.S. , Barzin J. , Jokar Z.
Published: September 2018

Reverse osmosis membranes were prepared by the phase inversion technique using polyether sulfone (PES) dissolved in dimethylacetamide (DMAc) with and without the addition of polyvinylpyrrolidone (PVP). The effects of the composition of the casting solution on membrane morphology and performance were investigated on the basis of ion removal from treated water. The membrane prepared from 22 wt.% PES demonstrated the best ion rejection. Higher flux was accessible by changing the polymer solution composition to 16 wt.% PES and 2.5 wt.% PVP. For preparation of polyamide composite membranes, the interfacial polymerisation technique was employed. In this procedure, hexamethylenediamine (HMDA) and sebacyl chloride (SC) were reacted with each other on the surface of a membrane support. Synthesis conditions, such as the concentration of monomers and the reaction time, significantly affect the performance of the composite membranes. The permeation rate and ion rejection capability of composite polyamide membranes were 40–80 (L/m2 h) and 28–30% respectively with the initial feed conditions of 400 psi and 25 °C.
Temperature Dependent Mechanical Characterisation of Styrene-Acrylonitrile
Authors: Solakoglu Ilker , Ataoglu Senol , Gulluoglu Arif N. , Kadioglu Necla
Published: September 2018

Poly(styrene-co-acrylonitrile) (SAN) which is a random, amorphous, linear copolymer produced by copolymerising styrene and acrylonitrile was investigated experimentally. Specimens were supplied from a private company and they were analysed using a differential scanning calorimetry machine (DSC). The behaviour of the material in creep, tension and hardness experiments was investigated experimentally at several temperatures. The creep response of SAN was also evaluated.
Preparation and Characterisation of Phase Change Material-Loaded Polyurea Microcapsules Several Hundred Micrometres in Diameter
Authors: Takei Takayuki , Yoshida Masahiro , Nagayoshi Tomonori , Hatate Yasuo , Shiomori Kouichiro , Kiyoyama Shiro
Published: September 2018

In the present study, we attempted to prepare phase-change material (PCM)-loaded polyurea microcapsules several hundred micrometres in diameter via oil-in-water emulsion polymerisation. An oil phase with two types of isocyanate monomers (2,4-toluene diisocyanate (TDI) and phenyl isocyanate (PI)) and tetradecane as PCM was dispersed in an aqueous phase with hexamethylene diamine (HMD). The polyurea shell of microcapsules was formed by reaction of the isocyanate monomers with the amine groups derived from HMD and hydrolysed isocyanate monomers. A suitably adjusted agitation rate made it possible to prepare the required microcapsules. An increased molar ratio of TDI to PI in oil phase resulted in improvement of microcapsule morphology. Increased weight ratio of tetradecane to the two isocyanate monomers (TDI and PI) led to an increase in the PCM content in the microcapsules, which is preferable for practical applications. An examination using differential scanning calorimetry analyser demonstrated that the polyurea shell of the microcapsules scarcely influenced the thermal properties of encapsulated tetradecane.
Potential Advantages of Poly(Acrylonitrile-Co-Methyl Acrylate)/Sodium Silicate Nanocomposites over P(An-Co-Ma) Copolymer
Authors: Samal Bijayashree , Rana Pradeep Kumar , Sahoo Prafulla Kumar
Published: September 2018

Poly (acrylonitrile-co-methyl acrylate) copolymer and P(AN-co-MA)/sodium silicate (SS) nanocomposite were synthesized via non-conventional emulsion method using an in situ transition metal complex Co(II)/EDTA and ammonium persulfate (APS) as initiator. The copolymer and nanocomposite so obtained were characterized and the results were compared. UV-visible spectral analysis revealed various interactions between the in situ complex and other reaction components. Infrared and 1H NMR spectra confirmed the formation of the P(AN-co-MA) copolymer and P(AN-co-MA)/SS nanocomposite. Furthermore, as evidenced by transmission electron microscopy (TEM), the composite obtained was found to have nano scale structure. X-ray diffraction (XRD) studies were carried out to analyze the aqueous dispersions of silicate with monomers, initiators, and monomers with initiators. For P(AN-co-MA) copolymer and P(AN-co-MA)/SS nanocomposite, XRD results confirmed that the silicate layers were exfoliated in the copolymer matrix during the polymerization process. An increase in the thermal stability for the nanocomposite was recorded by thermo gravimetric analysis (TGA). In comparison with the P(AN-co-MA) copolymer, the new P(AN-co-MA)/SS nanocomposite was found to show super absorbency and was biodegradable when tested by soil burial, activated sludge and cultured media and further confirmed by scanning electron microscopy (SEM).
Studies on Oxalic Acid as a Crosslinker of Polyvinyl Alcohol
Authors: Gohil J.M. , Ray P.
Published: September 2018

The suitability of oxalic acid as a crosslinker of polyvinyl alcohol (PVA) is the focus of study of the present paper. Oxalic acid concentration was varied from 3–70% (w/w with respect to polymer) and curing was carried out at various temperatures (100–140 °C) for a range of time periods (20–120 minutes). The optimum curative dose and curing conditions were evaluated through systematic swelling studies (% swelling, gel content, swelling ratio and molecular weight between the crosslinks) of the oxalic acid-treated PVA films, both in hot and cold water. Thermogravimetric analysis showed higher heat stability of oxalic acid crosslinked PVA film compared with heat-treated and virgin PVA. The shift in glass transition temperature (from that of virgin PVA 86 °C) to a higher value for heat-treated and oxalic acid-treated PVA was more prominent for the former than the later. Crosslinking enhanced the Young's modulus and IR spectra indicate the formation of ester carbonyl group in crosslinked PVA.
Ftir Spectroscopy: A Useful Tool for Structural Determination of Polyaniline and its Nanocomposites
Authors: Arasi A. Yelil , Jeyakumari J. Juliet Latha , Sundaresan B. , Dhanalakshmi V. , Anbarasan R.
Published: September 2018

Poly(aniline) nanocomposites were obtained by polymerisation under various experimental conditions including variation of time, temperature, monomer and concentration of initiators. The ratios of imino and amino units were estimated and correlated the with polyaniline (PANI) structure. Rates of polymerisation (Rp) values were estimated by a gravimetric method. TGA counsels the thermal stability of PANI. Through FTIR study, the structure of PANI/As2O3 nanocomposites was recognised. Comparison of polyanilines produced with two different initiators was done.
Mechanical Properties of Injection-Moulded Jute/Glass Fibre Hybrid Composites
Authors: Ohta Tomoko , Takai Yoshihiro , Leong Yew Wei , Hamada Hiroyuki
Published: September 2018

In order to improve the mechanical performance of natural fibre composites, glass fibres (GF) and natural fibres were simultaneously incorporated into a single matrix system. Such a practice would of course decrease the “degree of green”, which measures the amount (in weight percentage) of natural materials in a composite system. Nevertheless, it was found that hybrid composites containing up to 20 wt.% jute fibres exhibited similar tensile properties to those of glass fibre composites. The distribution of glass and jute fibres was anisotropic, wherein the GF tend to accumulate at the skin regions of the mouldings, thus orientating towards the resin flow direction. Jute fibres, on the other hand, tend to remain at the core regions and were mostly oriented transverse to the flow direction. This anisotropic distribution and orientation are thought to be responsible for the weakening of the composites at high natural fibre loadings.
Characterization of Polyamide 6/Superfine Silk Powder Blend Films
Authors: Liu Xin , Xu Weilin , Li Wenbin
Published: September 2018

Superfine silk powder (SSP) was blended and extruded with polyamide 6 (PA6) to produce blend pellets, and the extruded pellets were hot-pressed into blend films. The average particle size of the SSP was 3.5 μm. SEM photographs of blend films showed that SSP was uniformly distributed in the PA6 matrix and was compatible with it. ATR-FTIR and WXRD results showed that the addition of SSP favoured the formation of γ-monoclinic crystals of PA6 in the blend films. DSC patterns indicated the nucleating ability of SSP, which accelerated the crystallization process of the PA6 matrix. The mechanical properties of the blend films decreased somewhat, compared with that of pure PA6 film. K/S curves indicated that the dying properties were dependent on SSP content. It was worth noting that the K/S value of blend films containing 50 wt.% SSP at the wavelength of 510 nm achieved an increase of 461% compared with that of pure PA6 film.
Synthesis of Novel Donor-Acceptor Polymer Blends and Their Properties
Authors: Sabagh Bassem , Foot Peter J.S.
Published: September 2018

A novel kind of self-doped conducting polymer blend has been produced. Poly[3-(2-methoxyethoxy)-ethoxymethylthiophene-2,5-diyl] was chosen as the electron-rich (donor) conducting polymer and poly (3-nitropyridine-2,5-diyl) (PPyr-3-NO2) was chosen as the electron-deficient (acceptor) polymer. The latter was synthesised following a revised literature method. The dopant-free conjugated polymers were dissolved in N,N-dimethylformamide and were mixed together in electrically-equivalent proportions. Solvent-cast films of the resulting blends were studied by UV and ESR spectrometry and by cyclic voltammetry, and evidence of charge transfer included the increased extent of conjugation observed by UV analysis, increased number of unpaired electrons found by ESR analysis, increased electronic conductivity and the shifts in the doping and dedoping peaks in cyclic voltammetry.
Solvent Uptake and Accelerated Solar Aging Studies of Cotton – Polypropylene Commingled Composite Systems
Authors: Tomlal Jose E. , Thomas P.C. , Jayanarayanan K. , Mathew Jacob , Joseph Kuruvilla
Published: September 2018

Natural fibre-reinforced thermoplastic composites have a significant role in non-structural applications. Natural fibres are biodegradable, renewable and of low cost, high toughness and possess good thermal properties. This work involved the study of solvent absorption of cotton/polypropylene (PP) side-by-side commingled composites in different solvents, its variation by chemical treatments, temperature, fibre content etc., the extent of tensile property deterioration by solar radiation in a solar light concentrator and by water diffusion. It was observed that though cotton is highly hydrophilic, the diffusion was a matrix-dominated phenomenon. The extent of moisture absorption increased with the fibre content but decreased on treatment with maleic anhydride-modified PP. The former added a greater number of hydrophilic hydroxyl groups while the latter consumed them and enhanced the fibre–matrix interfacial adhesion. Increase in temperature accelerated the rate of moisture absorption and reduced the time required for equilibrium swelling. Exposure to sunlight in solar concentrator deteriorated mechanical properties such as tensile strength and tensile modulus by weakening the fibre–matrix interfacial adhesion and by chain scission.