Published by De Gruyter

Volume 38 Issue 8

Issue of Journal of Polymer Engineering

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Contents
Journal Overview

Publicly Available August 25, 2018

Frontmatter

Page range: i-iii

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Material properties

June 2, 2018

Effects of calcium stearate as pro-oxidant agent on the natural aging of polypropylene

Fatima Bensaad, Naima Belhaneche-Bensemra

Page range: 715-721

Abstract

The aim of this work is to study the effects of calcium stearate (CaSt 2 ) as pro-oxidant agent on the degradation of polypropylene (PP) under natural exposure. For that purpose, PP samples containing various amounts of CaSt 2 were prepared and exposed in Boumerdes, Algeria (Mediterranean climate) for 12 months. Samples were taken off every 3 months and characterized. The evolution of mechanical properties was followed by tensile and hardness tests. The structural modifications of PP were investigated by Fourier transform infrared (FTIR) spectroscopy, whereas the changes in morphology were analyzed by optical microscopy. The results showed a sudden decrease of elongation at break since the 1st month of exposure and a progressive decrease of stress at break and hardness. FTIR analysis showed apparition of oxygen products (carbonyl and hydroperoxide groups) due to the degradation of PP and a significant increase of carbonyl index as a function of exposure time. Furthermore, formation of crazes and cracks occurred during natural aging of PP. All the considered properties were affected by the presence of CaSt 2 as pro-oxidant agent, but the results showed that the level of calcium stearate does not have a significant influence and a concentration of 5 wt% was sufficient to initiate the process of degradation.

April 13, 2018

Energy dissipation characteristics of crosslinks in natural rubber: an assessment using low and high-frequency analyzer

K. Anas, Samson David, R.R. Babu, M. Selvakumar, S. Chattopadhyay

Page range: 723-729

Abstract

The dynamic deformation of a viscoelastic material can cause heat generation. This heat generation is an aspect of energy dissipation. The present paper investigates the contribution of crosslink type and density on energy dissipation mechanism in natural rubber compounds. The influences of these elements are investigated using a very high frequency (VHF) analyzer (VHF 104) and a dynamical mechanical analyzer (DMA). The VHF 104 analyzer follows transmissibility and vibration isolation principle, whereas DMA works on dynamical mechanical the deformation principle. Higher crosslink density promotes lower heat generation in rubber compounds. Tan δ interpretation for energy dissipation characteristics of rubbery compounds should be done judiciously to avoid wrong interpretations. Polysulfidic linkages show higher damping ratios ( ζ ) than monosulfidic or disulfidic linkages due to their dissipative nature. The natural frequency ( ω n ) of a system at a given mass is the function of its crosslink density.

April 13, 2018

Improving the mechanical properties of Fe₃O₄/carbon nanotube reinforced nanocomposites by a low-magnetic-field induced alignment

Yifan Huang, Weicheng Jiao, Yue Niu, Guomin Ding, Rongguo Wang

Page range: 731-738

Abstract

The aim of the paper is to develop a novel nanocomposite with high mechanical properties. The mechanical properties are improved by aligning the Fe 3 O 4 /multi-walled carbon nanotubes (MWCNTs) into a highly oriented manner in epoxy resin (EP) via a low magnetic field. Fe 3 O 4 nanoparticles were tethered onto the surface of MWCNTs by a novel water-in-oil (W/O) method without heating at high temperatures or the protection of inert gas. Then, the modified magnetic MWCNTs (m-MWCNTs) were added into EP and aligned in a low magnetic field (100 mT). A method was presented to estimate the minimum magnetic field strength for aligning the m-MWCNTs. Besides, the morphology and microstructures of the fabricated m-MWCNTs and m-MWCNTs/EP highly ordered nanocomposites were characterized. Finally, the mechanical properties measurements were performed. The results of the experiments showed that this method was very efficient in aligning m-MWCNTs embedded in polymer matrix leading to a highly ordered composite for improving mechanical properties.

May 22, 2018

Carbon nanofiber reinforced thermoplastic elastomer based on polypropylene/polybutadiene blend: theoretical modeling of Young’s modulus of the nanocomposites with respect to the orientation and agglomeration of carbon nanofiber

P.G. Sreedevi, M.A. Shadiya, Joseph Rani

Page range: 739-748

Abstract

The effect of the concentration of carbon nanofibers (CNFs) on thermoplastic elastomer based on polypropylene/polybutadiene (PP/BR) blend (80/20) prepared by melt blending process was investigated. The morphological properties are reported in combination with the mechanical and rheological properties of the nanocomposites. The dispersion of CNFs examined by transmission electron microscopy shows uniform dispersion of CNFs in the PP matrix. The mechanical performance is found to be in line with the morphological structure observed in scanning electron microscopy. Tensile strength and Young’s modulus of the PP/BR blend increase with an increase of filler content up to 3 wt%. The modified Halpin-Tsai equation that accounts for the effect of orientation and agglomeration of CNF was used to evaluate the Young’s modulus of the nanocomposite. The dynamic rheological analysis in the frequency sweep experiment shows that the introduction of CNF in the PP/BR blend improves the complex viscosity ( ƞ *), storage modulus ( G ′), and loss modulus ( G ″) in the low-frequency region.

February 24, 2018

Usability of dielectric properties for evaluation and research of deconsolidation of endless fiber-reinforced thermoplastics

Tobias Mattner, Dietmar Drummer

Page range: 749-758

Abstract

Understanding the deconsolidation behavior of endless fiber-reinforced thermoplastics is essential for reliable predictions of parts behavior and advancements in the corresponding processing technologies. Deconsolidation is usually described by an increasing void ratio of the part volume arising due to fiber relaxation effects, which can strongly affect the mechanical performance. Most methods for measuring the degree of deconsolidation are destructive and require long testing or preparation times. As the dielectric permittivity of a material is usually proportional to its porosity, often reported in foam-related research, dielectric measurements are evaluated as a nondestructive alternative to identify the degree of deconsolidation of endless fiber-reinforced thermoplastics. Polypropylene and glass-woven–based organo-sheets are deconsolidated and density measurements are compared with dielectric measurements for their effect strength and measurement deviations. A relative permittivity in the range of 5–20 MHz was found to allow for a proper differentiation of different degrees of deconsolidation with a ratio of measurement deviation to sample deviation of 26.31% for a single-layer composite (42.96% for a four-layer composite). Additional research is required to identify all relevant influences and to further qualify the method for the research of the deconsolidation behavior or quality control.

April 25, 2018

Dispersion characteristics of hydroxyl and carboxyl-functionalized multi-walled carbon nanotubes in polyester nanocomposites

Muhammad Remanul Islam, Md. Dalour H. Beg

Page range: 759-765

Abstract

Multi-walled carbon nanotube (MWCNT) reinforced polyester-based composites were prepared by mixed blending in a solvent. Orthophthalic unsaturated polyester was blended individually with different types of non-functionalized and functionalized MWCNTs. Two types of functional groups: hydroxyl (-OH) and carboxyl (-COOH) were introduced with MWCNTs for the nanocomposites. The mechanical properties of the composites, like tensile, three-point bending and impact energy were evaluated. Fourier transform infrared spectroscopy was used for the functional group analysis. The dispersion characteristics of the samples were observed by transmission electron microscopy and field-emission electron microscopy. In addition, the thermal decomposition and melting behavior of the samples was assessed by differential scanning calorimetry and thermogravimetric analysis. The properties were varied due to the variation of the functional groups. The result analysis showed that the entangled agglomerations of hydroxyl-functionalized MWCNTs were destroyed to relatively smaller clusters. The hydroxyl-functionalized MWCNTs were more effective for homogeneous dispersion and contributed for better mechanical properties of the composites, compared to non-functionalized and carboxyl group-functionalized MWCNTs.

March 2, 2018

Enhanced thermal conductivity and flame retardancy of polyamide 6/flame retardant composites with hexagonal boron nitride

Liang Wang, Luchong Zhang, Andreas Fischer, Yuhua Zhong, Dietmar Drummer, Wei Wu

Page range: 767-774

Abstract

High performance composite of polyamide 6 (PA6)/flame retardant (FR)/hexagonal boron nitride (hBN) was prepared via twin screw extrusion, followed by injection molding. The heat dissipation of the composite was significantly improved by incorporating 40 vol% of hBN, and the corresponding thermal conductivity was up to 5.701 W/(m·K), nearly 17 times that of the PA6/FR composites. In addition, the combination effect of hBN and FR to the flame retardancy of the composites was observed, and the addition of hBN could dramatically enhance the flame retardancy of composites, achieving a UL94 V-0 rating with a limited oxygen index (LOI) value of 37%. This multifunctional modification would broaden the application field of PA6 composites in light-emitting diode (LED) lamps, electronic products, and so on.

March 15, 2018

Effect of drying parameters on the physical, morphological and thermal properties of spray-dried inulin

Israr Ahmed, Muhammad Bilal Khan Niazi, Zaib Jahan, Salman Raza Naqvi

Page range: 775-783

Abstract

This study focuses on the thermal, morphological and physical properties of spray-dried chicory root inulin using a thermogravimetric analyzer, environmental scanning electron microscopy, X-ray diffractogram and modulated differential scanning calorimetry. Different spray-drying conditions were investigated by varying inlet temperature, outlet temperature and aspirator speed. The starting material was semicrystalline. A feed temperature of 95°C was employed, which produced a completely transparent solution for spray drying. At that particular temperature, the powder samples obtained were entirely amorphous and morphology resembled each other except for higher solid content. The low glass transition temperature ( T g ) (106.83°C) was evident by treating low-molecular-weight samples, whereas high-molecular-weight samples exhibited high T g (125.81°C). The semicrystalline samples due to the high concentration and milky dispersion exhibited high decomposition temperature. The feed temperature, molecular weight and concentration of the samples tend to have a significant effect on the properties of spray-dried inulin.

March 29, 2018

Morphology and thermal properties of clay based biocomposites

Leila Bounabi, Naima Bouslah Mokhnachi, Amar Djadoun, Nabila Haddadine, Regis Barille

Page range: 785-793

Abstract

Carboxymethylcellulose/poly(ethylene glycol) (CMC/PEG) blend and CMC/PEG/montmorillonite (MMT) nanocomposites were produced by the solvent casting method. The clay, a sodium MMT, was incorporated in the polymer matrix at low weight loadings (from 1 wt% to 7 wt%). The MMT dispersion in the matrix was evaluated by X-ray diffraction, which revealed an intercalated structure of the nanocomposites. Different levels of intercalation have been detected. The changes in morphology caused by the addition of layered silicate on CMC/PEG blend were investigated by scanning electron microscopy (SEM). The SEM images of CMC/PEG blend containing 5% of MMT displayed more homogenous morphology than CMC/PEG blend. The compatibilizing performance of the filler was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. The effect of the introduction of the clay on the crystallization temperature, melting temperature and crystallization degree of CMC/PEG revealed that clay behaved as a nucleating agent and enhanced the crystallization rate of PEG. Furthermore, it was demonstrated that the addition of a small percentage of montmorillonite (1%) was enough to improve the thermal stability of the nanocomposites.

Preparation and assembly

February 21, 2018

Active screen plasma system applied to polymer surface modification: poly(lactic acid) surface activation before polyaniline graft polymerization in aqueous medium

Janaína G. Alonso, Carla Dalmolin, Jacimar Nahorny, Abel A.C. Recco, Luis C. Fontana, Daniela Becker

Page range: 795-802

Abstract

An active screen plasma system (ASPS) was used for the surface activation of poly(lactic acid) (PLA) as a pretreatment before the oxidative graft polymerization of polyaniline (PANI). In ASPS, the plasma glow discharge occurs outside the grid, and the samples to be treated are placed inside the cage where they are subjected to a floating potential (about −12 V). An increase in hydrophilicity was observed for all samples after Ar plasma treatment. In addition, a decrease in thermal stability and changes in crystallization behavior were observed for PLA samples treated for a longer time. After PANI graft polymerization, smoothing of the surface topography was noticed in samples treated for short time periods. Such a change in the topography, in addition to surface activation, provides better conditions for subsequent PANI grafting.

August 7, 2018

Silver polymer nanocomposites by photoreduction of AgNO₃ and simultaneous photocrosslinking of the acrylic matrix: effect of PVP on Ag particle formation

Rabia Nazar, Marco Sangermano, Alessandra Vitale, Roberta Bongiovanni

Page range: 803-809

Abstract

We studied the effect of poly-N-vinylpyrrolidone (PVP) and its concentrations on the photoinduced formation of silver nanoparticles (Ag NPs) as well as Ag-polymer nanocomposites. First, the effect of PVP concentration on the photoinduced reduction of Ag nitrate (AgNO 3 ) in solution was studied by UV-Vis absorption spectroscopy monitoring the plasmon band of Ag. Dynamic light scattering (DLS) results showed that Ag NPs formed in the presence of stabilizer up to 4 wt% were narrower; the size distribution was also narrower. The PVP also had a significant influence on the formation of polymer nanocomposites by simultaneous photoinduced synthesis of NPs and polymerization of the acrylic matrix; NPs embedded in the crosslinked polymer were well dispersed, as detected by field-emission scanning electron microscopy (FESEM), and showed an average diameter of 20 nm.

Publicly Available August 1, 2018

Preparation and characterization of silica aerogel/polymethyl methacrylate composites with electrostatic interaction phase interface

Hongyan Li, Cong Sun, Ruyi Li, Yongqiang Fu, Limeng Song, Aiwu Yang, Hongli Liu

Page range: 811-818

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Abstract

Silica aerogel (SA)/polymethyl methacrylate (PMMA) composites were prepared through electrostatic interaction, which could form phase interface. The effects of electrostatic interaction phase interface on the performance of the composites were studied. The SA/polymer hybrid composites were prepared because of the negative charges in SA and the positive charges in polymer. Characterizations of the SA, polymer, and composites were performed using Fourier transform infrared spectroscopy, scanning electron microscopy, transmittance, gel permeation chromatography, differential scanning calorimetry, zeta potential, and so on. The results indicated that SA has negative charges, whereas the polymer has positive charges; thus, the polymer was absorbed on the surface of the SA skeleton to form an electrostatic interaction phase interface. The composites achieved better transmittance than that of SA/PMMA with the electrostatic interaction phase interface.

About this journal

Objective
Journal of Polymer Engineering publishes reviews, original basic and applied research contributions as well as recent technological developments in polymer engineering. Polymer engineering is a strongly interdisciplinary field and papers published by the journal may span areas such as polymer physics, polymer processing and engineering of polymer-based materials and their applications. The editors and the publisher are committed to high quality standards and rapid handling of the peer review and publication processes.

Topics
Cutting-edge topics such as but not limited to the following:

Polymer physics
Polymer processing
Functional polymers
Engineering of polymer composites, nanocomposites and blends
Biopolymer engineering
Engineering of polymer-based materials for electrical, piezoelectrical and optical applications
Polymers and renewable energies
Environmental polymer engineering
Automotive and aerospace
Nanotechnology
Photonics and optoelectronics

Article formats
Original articles, Reviews

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Volume 38 Issue 8

Issue of Journal of Polymer Engineering

Frontmatter

Effects of calcium stearate as pro-oxidant agent on the natural aging of polypropylene

Abstract

Energy dissipation characteristics of crosslinks in natural rubber: an assessment using low and high-frequency analyzer

Abstract

Improving the mechanical properties of Fe3O4/carbon nanotube reinforced nanocomposites by a low-magnetic-field induced alignment

Abstract

Carbon nanofiber reinforced thermoplastic elastomer based on polypropylene/polybutadiene blend: theoretical modeling of Young’s modulus of the nanocomposites with respect to the orientation and agglomeration of carbon nanofiber

Abstract

Usability of dielectric properties for evaluation and research of deconsolidation of endless fiber-reinforced thermoplastics

Abstract

Dispersion characteristics of hydroxyl and carboxyl-functionalized multi-walled carbon nanotubes in polyester nanocomposites

Abstract

Enhanced thermal conductivity and flame retardancy of polyamide 6/flame retardant composites with hexagonal boron nitride

Abstract

Effect of drying parameters on the physical, morphological and thermal properties of spray-dried inulin

Abstract

Morphology and thermal properties of clay based biocomposites

Abstract

Active screen plasma system applied to polymer surface modification: poly(lactic acid) surface activation before polyaniline graft polymerization in aqueous medium

Abstract

Silver polymer nanocomposites by photoreduction of AgNO3 and simultaneous photocrosslinking of the acrylic matrix: effect of PVP on Ag particle formation

Abstract

Preparation and characterization of silica aerogel/polymethyl methacrylate composites with electrostatic interaction phase interface

Abstract

Improving the mechanical properties of Fe₃O₄/carbon nanotube reinforced nanocomposites by a low-magnetic-field induced alignment

Silver polymer nanocomposites by photoreduction of AgNO₃ and simultaneous photocrosslinking of the acrylic matrix: effect of PVP on Ag particle formation