bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of the Crystallization Behaviour of Dynamically Vulcanized EPDM/Nylon Copolymer Blends
Authors: Liu Xin , Huang Hua , Zhang Yong , Zhang Yinxi
Published: September 2018

In this work the crystallization kinetics of polyamide copolymer (PA) in PA/ ethylene-propylene-diene rubber (EPDM) thermoplastic vulcanizates was studied under non-isothermal and isothermal conditions from the melt. A differential scanning calorimeter was used to monitor the energetics of the crystallization process. The effects of rubber, compatibilizer, vulcanizing agents, and the process methods on the isothermal and non-isothermal crystallization of PA were investigated. Relative crystallinity develops in accordance with the time dependence described by the Avrami equation with the exponent n ≈ 3. The experimental results show that the EPDM rubber is not the nucleating agent in those samples that were not dynamically vulcanized. The addition of chlorinated polyethylene has no effect on the crystallization of PA. But in dynamically vulcanized samples the EPDM rubber is a nucleating agent and the addition of chlorinated polyethylene helps the EPDM to form fine and well-dispersed particles and improves the crystallization of PA.
A Coupled Hygrothermal Cohesive-Layer Constitutive Model for Simulating Debond Growth
Authors: Roy Samit , Shiue Fuh-Wen
Published: September 2018

The objective of this paper is to model the synergistic bond degradation mechanisms that may occur at the interface between a Fiber Reinforced Polymer (FRP) and concrete. For this purpose, a two-dimensional cohesive layer constitutive model with a prescribed traction-separation law is constructed from basic principles of continuum mechanics and thermodynamics, taking into account non-Fickian hygrothermal effects that are likely to occur within the cohesive layer. The model is implemented in a test-bed finite element code (NOVA-3D). Benchmark comparisons of finite element predictions with analytical results for a double cantilever beam specimen for model verification are performed. Results from demonstration cases involving bond degradation are also presented.
Dispersibility of Macromolecular Polyols as Co-Stabilizer in Poly(vinyl Chloride) and their Stabilization Effect Combined with Synergetic Metal Soap
Authors: Ikeda Hirohisa , Ishikawa Masanori , Nakamura Yoshinobu , Iida Takeo
Published: September 2018

In order to delay the undesirable discoloration of poly(vinyl chloride) (PVC) by heating, the synergetic effect of poly(vinyl alcohol) (PVA) as co-stabilizer with a mixture of zinc and calcium stearates was clarified. Usually, the abrupt discoloration was caused by the formation of a π-complex between the cool colour-producing metal chloride, i.e. the zinc chloride from the metal soap, and double bonds from the dehydrochlorination of the PVC chain. Firstly, the effect of using various PVA having different degrees of polymerization before melt blending with PVC was investigated. When the PVA and PVC were pre-mixed in the powder state, the compound obtained showed a lower stabilization effect on the discoloration of PVC. On the other hand, when a PVA aqueous solution was prepared and the PVC powder was added to the PVA solution, and dried, the resulting compound showed an excellent stabilization effect. Secondly, the dispersed PVA domain size in the PVC sheets was measured quantitatively by image processing analysis, using the optical micrographs of the sheets. As a result, it was found that there was a good relationship between the dispersibility of PVA and its stabilization effect. That is, the co-stabilizing effect of PVA increased with a decrease in the domain size. This fact was also confirmed by using different polyols as co-stabilizer.
Modelling Orthotropic Viscoelastic Behaviour of Composite Laminates Using a Coincident Element Method
Authors: Nallainathan L. , Liu X.L. , Chiu W.K. , Jones R.
Published: September 2018

In this paper a finite element procedure for modelling the viscoelastic behaviour of orthotropic composites is presented. The procedure uses the commercially available finite element package ABAQUS and requires no code development. The procedure utilises two coincident shell elements to model the orthotropic viscoelastic behaviour of a composite laminate. The first element exhibits isotropic and viscoelastic behaviour, while the second element exhibits orthotropic and elastic behaviour. The elements are superimposed in such a way that they are coincident. That is, the two shell elements share the same nodes and hence deform together. Consequently, it is expected that this combined hybrid model will exhibit combined orthotropic and viscoelastic behaviour. Numerical examples are presented to illustrate the capability and accuracy of the new procedure.
Dynamically Cured PP/Epoxy Blends Compatibilised with MAH-g-PP
Authors: Jiang Xueliang , Huang Hua , Zhang Yong , Zhang Yinxi
Published: September 2018

The dynamic vulcanization process usually used to prepare thermoplastic elastomers was used to prepare polypropylene (PP)/epoxy blends compatibilised with maleic anhydride-grafted PP. The influence of dynamic cure, MAH-g-PP content, curing agents and epoxy equivalent weight on the mechanical properties of the PP/MAH-g-PP/epoxy blends was investigated. The torque at equilibrium of the blends increased with increasing epoxy resin content. The blends had better mechanical properties than either uncured PP/epoxy or dynamically cured PP/epoxy blends. The flexural modulus and impact strength increased rapidly with increasing MAH-g-PP content and reached a maximum of 2030 MPa and 36 J/m, respectively, at an MAH-g-PP content of 10 wt%. Those blends made using 2-ethylene-4-methane-imidazole as the curing agent had higher impact strength and flexural modulus than the ones made using dicyandiamide. The dynamically cured PP/MAH-g-PP/epoxy blends exhibited better mechanical properties at an epoxy equivalent of 2000 g/mol. The flexural modulus increased significantly with increasing epoxy resin content, while the elongation at break dramatically decreased, and the impact strength was only slightly affected by the presence of the epoxy resin. The PP/epoxy blends compatibilised with MAH-g-PP had finer domains than those of PP/epoxy blends. The FTIR spectra show that the functional groups of MAH-g-PP reacted with the epoxy resin.

Dynamic mechanical thermal analysis (DMTA) results indicate that the compatibility between the PP and epoxy resin was improved by the addition of MAH-g-PP, and the storage modulus ( E') increased with increasing epoxy resin content. Thermogravimetric analysis (TGA) results show that the incorporation of epoxy resin into PP could improve the thermal stability of PP, and the dynamically cured PP/MAH-g-PP/epoxy blends had better thermal stability than the PP/epoxy and PP/MAH-g-PP/epoxy blends.
Responding to the Consumers' Desire for Improved Hygiene with Antibacterial Plastics
Authors: Payne John
Published: September 2018

Ever-increasing numbers of plastics articles are made with built-in antibacterial performance - from kitchen utensils to air filters, flooring and calculators. They carry claims ranging from protecting health and improving hygiene to odour control and freshness.

Market research was therefore commissioned in order to understand consumers' views on these products. There was a strong positive response to the incorporation of antibacterial performance in domestic articles used around children, and in those with food and medical uses. There was even greater interest in antibacterial products in public areas, such as restaurants, hospitals, and transportation.

Avecia have launched a range of antibacterial additives aimed at polyolefins and PVC. Experimental data have been generated on antibacterial PVC, using a quantitative method, the JIS Test Method Z2801, with two relevant organisms. Interpretation of the raw data to support performance claims is detailed. The company has also developed a growing business in antibacterial consumer products, supported by the co-brand Purista™. Initially aimed at textiles, the co-brand is now available to manufacturers of plastic articles, provided performance and marketing standards are met. An example of use of the Purista™ co-brand is the labelling of PVC cooler bags.
Durability of Isophthalic Polyester Composites Used in Civil Engineering Applications
Authors: Dagher H. J. , Iqbal A. , Bogner B.
Published: September 2018

Fiber Reinforced Polymer (FRP) composites are increasingly used in civil infrastructure applications, primarily because of their high strength-to-weight ratio and corrosion resistance. Further deployment of FRP in the construction market will be accelerated by using low-cost, durable matrix materials. In this paper, published research on the durability of a low-cost matrix, isophthalic polyester (IPE), is reviewed and the results are compared to the durability of the more expensive vinyl ester (VE). The objective is to evaluate the suitability of IPE in civil engineering applications, particularly in conjunction with concrete and high alkaline environments. The analysis indicates that, although vinyl esters are generally more durable than isophthalic polyesters, the performance difference does not always appear to be very significant. More importantly, the literature review revealed that the data on the durability of IPE in concrete and alkaline solutions is of limited usefulness. Since this is the kind of information needed to evaluate IPE's effectiveness in construction applications, further research in these areas is recommended.
Structure and Mechanical Properties of Injection Moulded CF/LCP Thin Plates
Authors: Baba Fumiaki , Fujita Akihiro , Gon Chimyon , Nakai Asami , Hamada Hiroyuki
Published: September 2018

The effect of injection speed on the structure and bending properties of carbon fibre (CF) reinforced liquid crystal polymer (LCP) injection moulded plates were investigated. The distribution of the modulus in injection moulded LCP and CF/LCP thin plates made using two different injection speeds was investigated by taking slices at 0.1 mm intervals. Moreover the modulus of the CF/LCP thin plate was estimated by the Cox formula and by laminate theory from values of the fibre orientation and modulus of each LCP layer. It was found that the differences in the bending properties and structures due to changes in injection speed were not remarkable. The differences in the fracture behaviours with changes in the cutting position were caused by the differences in the modulus of each layer as in the laminated composite. It was confirmed that injection moulded CF/LCP can be treated in general as a laminated composite, and that the distribution of the modulus in injection moulded CF/LCP could be evaluated by the slicing technique. Comparing the calculated modulus with the experimental one in the machine direction and the transverse direction revealed that the degree of local orientation of the LCP domains near the fibres was different from that of LCP without any fibre. Moreover, it was shown by evaluating the fibre orientation and modulus of the sliced specimens that fibre orientation contributed to the difference in the modulus near the surface when the injection speed changed. It was also verified that the prediction method suggested in this paper is valid to estimate the modulus of thin injection moulded CF/LCP plates.
Combined Isotropic-Kinematic Hardening Laws with Anisotropic Back-stress Evolution for Orthotropic Fiber-Reinforced Composites
Authors: Lee M.G. , Kim D. , Chung K. , Youn J. R. , Kang T. J.
Published: September 2018

In order to describe the Bauschinger and transient behavior of orthotropic fiber-reinforced composite solids, a combined isotropic-kinematic hardening law based on the non-linear kinematic hardening rule was considered here, in particular, based on the Chaboche type law. In this modified constitutive law, the anisotropic evolution of the back-stress was properly accounted for. Also, to represent the orthotropy of composite materials, Hill's 1948 quadratic yield function and the orthotropic elasticity constitutive equations were utilized. Furthermore, the numerical formulation to update the stresses was also developed based on the incremental deformation theory for the boundary value problems. Numerical examples confirmed that the new law based on the anisotropic evolution of the back-stress complies well with the constitutive behavior of highly anisotropic materials such as fiber-reinforced composites.
Preparation and Properties of Semi-Transparent EPDM/Montmorillonite Nanocomposites
Authors: Zheng Hua , Zhang Yong , Peng Zonglin , Zhang Yinxi
Published: September 2018

Ethylene-propylene-diene rubber (EPDM)/organic montmorillonite (OMMT) nanocomposites were prepared through a melt-mixing process in an internal mixer. The nanoscale dispersion of OMMT in the EPDM matrix was verified by X-ray diffraction (XRD) and transmission electron microscopy (TEM), relating to an exfoliated morphology. The effects of OMMT content on the mechanical properties, curing behaviour, optical properties and thermal properties of the EPDM/OMMT nanocomposites were studied. The experimental results showed that OMMT had good reinforcement on the EPDM vulcanizates. The tensile strength and tear stress of the EPDM/OMMT nanocomposites significantly increased with increasing OMMT content. When the OMMT content was 15 phr, the tensile strength and elongation at break reached 19.8 MPa and 540%, respectively. The EPDM/OMMT nanocomposite cured by 2,5-dimethyl-2, 5-bis (tert-butyl peroxy) hexane was semi-transparent and the OMMT content had little influence on the curing behaviour of the nanocomposites. The increases in the glass transition temperature and thermal decomposition temperature were observed in the nanocomposites and were supposed to be related with the nanoscale dispersion of the OMMT and the strong interaction between EPDM and OMMT. Moreover, the permeability of oxygen for the EPDM/OMMT nanocomposites was reduced remarkably.
Preparation and Properties of a Water-Swelling Rubber by in situ Formed Lithium Acrylate in Nitrile Rubber
Authors: Ren Wentan , Peng Zonglin , Zhang Yong , Zhang Yinxi
Published: September 2018

Lithium acrylate (LiAA) was in situ prepared in nitrile rubber (NBR) through neutralization of lithium hydroxide (LiOH) and acrylic acid (AA) during mixing. The NBR/LiAA compounds were vulcanized with dicumyl peroxide (DCP). The in situ preparation and polymerization of LiAA were characterized using Fourier transform infrared (FTIR) spectrometer. The micrographs of the compounds and vulcanizates were explored using a scanning electron microscope (SEM). The effects of DCP and LiAA contents on the water-swelling and mechanical properties of the vulcanizates were studied. The relationship between the LiOH/AA molar ratio and the properties of the vulcanizates was investigated. The results showed that the in situ formed LiAA could improve the mechanical properties and water–swelling properties of the NBR/LiAA vulcanizates. The vulcanizates properly compounded had high water-swelling ratio over 800% and tensile strength more than 12MPa. The differential scanning calorimetry (DSC) measurements indicated that the water absorbed in the vulcanizate existed in PLiAA and NBR networks in three different physical states, namely, free water, freezable bound water and non-freezable bound water.
Numerical Prediction of Permeability Tensor for Three Dimensional Circular Braided Preform by considering Intra-tow Flow
Authors: Song Y.S. , Chung K. , Kang T.J. , Youn J.R.
Published: September 2018

Resin transfer moulding is characterized by the permeability tensor, which is a measure of the resistance to resin flow through the preform. Complete prediction of the second order permeability tensor for three dimensional circular braided preforms is critical to an understanding of the resin transfer moulding process. The permeability can be predicted by considering resin flow through the multi-axial fibre structure. In this study, the permeability tensor for a 3-D circular braided preform was calculated by solving a boundary problem of a periodic unit cell. The flow field through the unit cell was obtained by using a 3-D control volume finite element method (CVFEM) and Darcy's law was utilized to obtain the permeability tensor. The flow analyses were carried out for two cases, one in which the fibre tow was regarded as a permeable porous medium, and one in which it was regarded as an impermeable solid. It was found that the flow within the intra-tow region of the braided preform was negligible if the inter-tow porosity was relatively high, but flow through the tow, especially flow in the thickness direction must be considered when the porosity is low. The permeability of the braided preform was measured by a radial flow experiment and compared with the predicted permeability.
Fatigue Life Estimation of Adhesively Bonded Scarf Joints Based on a Continuum Damage Mechanics Model
Authors: Imanaka Makoto , Taniguchi Makoto , Hamano Tatuyuki , Kimoto Masaki
Published: September 2018

An estimation method of fatigue strength of adhesively bonded joints with various stress triaxialities in the adhesive layer has been proposed based on a damage evolution model for high cycle fatigue. To realize various triaxial stress states, fatigue test was conducted for adhesively bonded butt and scarf joints with various scarf angles bonded by a rubber-modified epoxy adhesive. An equation for estimating the damage evolution in the adhesive layer of the butt and scarf joints was derived from the damage model, where undefined parameters in the equation were determined by comparing the experimentally obtained damage evolution curves of the butt joints with the estimated damage evolution curves. Furthermore, an equation for the estimation of fatigue strength was derived under the assumption that fatigue failure occurs when the damage variable reaches to a critical value. When compared the experimental S-N data of scarf joints with the estimated ones, the estimated fatigue strengths agree well with the experimental data with various scarf angles. This finding suggests that the CDM model is applicable for estimating fatigue strength of adhesively bonded joints with different stress triaxialities.
Toughening Modification of Poly(butylene terephthalate)/Polycarbonate Blends by Poly(ethylene-co-octene)
Authors: Bai Huiyu , Zhang Yong , Zhang Yinxi , Zhang Xiangfu , Zhou Wen
Published: September 2018

New toughened poly(butylene terephthalate) (PBT)/bisphenol A polycarbonate (PC) blends were obtained by melt blending with commercial poly(ethylene-co-octene) copolymer (POE), varying the POE content up to 10 wt%, in a twin screw extruder, followed by injection moulding. The influence of POE on the properties of the PBT/PC blends was investigated in terms of mechanical testing, dynamic mechanical thermal (DMTA) analysis, differential scanning calorimetry (DSC), and scanning electronic microscopy (SEM). The results showed that addition of POE led to remarkable increases in the impact strength, elongation at break and Vicat temperature, and a reduction in the tensile strength and flexural properties of PBT/PC blends. The morphology of the blends was observed using SEM and the average diameter of the dispersed phase was determined by image analysis. The critical inter-particle distance for PBT/PC was determined.
Synthesis and Characterization of Reactive Graft Copolymers of Poly(butyl Acrylate) and Cellulose
Authors: Chauhan Ghanshyam S. , Singh Baljit , Kumar Suresh , Chinkara Anupama
Published: September 2018

Butyl acrylate was graft copolymerized onto cellulose extracted from pine needles by a simultaneous gamma radiation initiation method. Optimum conditions for the maximum graft yield were established. Polymerization and grafting parameters such as %grafting (Pg), % grafting efficiency (%GE), rates of polymerization (Rp), homopolymerization (Rh) and graft copolymerization (Rg) were also determined. Grafted cellulose was further functionalized to produce poly(acryloyl hydroxylamine) [Cell-g-poly(CONHOH)] so as to generate active (-CONHOH) groups on the cellulose backbone.

Graft copolymers were characterized by elemental analysis, by FT-IR and by a swelling study. An attempt was also made to study the sorption of Fe+2 and Cu+2 as model metal ions onto the candidate copolymers, in order to investigate their selectivity in metal ion sorption and to determine the effect on metal ion sorption of the structural aspects of the hydrogels and other functionalized graft copolymers, so as to identify their end-uses.
Influence of Chopped Fibre Length on the Mechanical and Thermal Properties of Silk Fibre-Reinforced Poly(Butylene Succinate) Biocomposites
Authors: Lee Sang Muk , Han Seong Ok , Cho Donghwan , Park Won Ho , Lee Seung Goo
Published: September 2018

The influence of chopped fibre length on the mechanical and thermal properties of silk fibre ( Bombix mori) reinforced poly(butylene succinate) (PBS) biocomposites has been investigated in terms of tensile and flexural properties, thermal stability, thermal expansion, and dynamic mechanical properties. The chopped fibre lengths studied were 3.2 mm, 6.4 mm, 12.7 mm, and 25.4 mm. The results demonstrate that chopped silk fibres play an effective role in improving the mechanical properties of PBS in the present system. At a fixed fibre loading of 40 wt%, the tensile strength and modulus of the PBS control were improved by 69% and 228%, respectively, in comparison with those of the biocomposite reinforced with 25.4 mm silk fibres. The flexural strength and modulus of PBS were also greatly improved by 167% and 323%, respectively. The thermal properties of PBS resin increased when incorporating chopped silk fibres in the composite matrix. The biocomposites had much lower linear coefficient of thermal expansion (CTE) values and higher storage moduli than the PBS controls above the glass transition region, especially with reinforcing silk fibres of 25.4 mm long.
On the Transient Hygroscopic Stresses in Polymer Matrix Laminated Composites Plates with Cyclic and Unsymmetric Environmental Conditions
Authors: Tounsi A. , Bouazza M. , Meftah S. , Adda-Bedia E.
Published: September 2018

The use of aircraft structural parts made of polymer matrix composites subjected to severe environment conditions calls for better knowledge of their long – term behaviour, with an emphasis on their ability to withstand important cyclic variations of moisture and temperature. The influence of temperature and moisture on such structures is receiving special attention, because it induces transient residual stresses within the plies. Such stresses must be taken into account in the design of composite materials, particularly aerospace structures, e.g. aircraft. In the present paper the transient hygroscopic stresses induced by cyclic and unsymmetric environmental loadings which simulate an aeronautical application are investigated. It is shown that the heterogeneity and anisotropy of such plates generally result in transient stress distributions which are very different from the equilibrium stress distribution. Some stacking sequences exhibit important stresses within the plies. These stresses have to be taken into account in the design of composite structures submitted to a moist environment.
Effect of Flexible Polymer Coating on Interfacial Adhesion of Glass Fibre Reinforced Polypropylene
Authors: Zhou Xiaodong , Lin Qunfang , Xiong Ruohua , Cui Xinyu , Dai Gance
Published: September 2018

Polymer coatings were obtained by using two rubbers, cis-polybutadiene rubber and ethylene-propylene diene monomer and two block copolymer: polystyrene-block-polybutadiene-block-polyvinyltriethoxysilane and polystyrene -block-polyvinyltrietho xysilane. They were used to coat glass fibre surfaces. The effects of the coatings on the interfacial adhesion and thermal cycling resistance of composites were studied by a single-filament fragmentation technique designed to measure the interfacial shear strength of glass fibre reinforced polypropylene.

The interfacial shear strength was improved by the rubber coatings, which could graft to silane coupling agents coated onto the fibre surfaces, and could undergo crosslinking under peroxide initiation. The interfacial bond strength was determined by the nature and thickness of the rubber coatings.

The interfacial adhesion was also improved when using block copolymers to treat glass fibres. The rubbers and those copolymers having flexible blocks in their chain structures both produced coatings that could relieve the thermal stresses at the composite interface during temperature cycling. The interface between the composites and the flexible polymer coatings had good thermal cycling fatigue resistance.
Prediction of Thermal Conductivities of Fibre Reinforced Composites using a Thermal-Electrical Analogy
Authors: Cho Young Jun , Youn Jae Ryoun , Kang Tae Jin , Kim Sung Min
Published: September 2018

An approach for predicting the effective thermal conductivities of fibre reinforced composites has been developed, based on a thermal-electrical analogy. In the voxelization method, the unit cell of the laminate composites is divided into a number of volume elements, and the material properties considering the local variations of fibre orientation have been given to each element. By constructing a series-parallel thermal resistance network, the thermal conductivities of a fibre reinforced composite in both in-plane and out-of-plane directions have been predicted. The reported thermal conductivities of a graphite/epoxy composite of a balanced plain weave laminate were used for the comparison with the predicted values of the model, and good agreement was found.
Analytical Solution for Cohesive Layer Model and Model Verification
Authors: Roy Samit , Wang Yong
Published: September 2018

The objective of this work was to find an analytical solution to the stresses in the cohesive damage zone and the damage zone length at the interface between a fibre reinforced polymer (FRP) plate and concrete substrate. Analytical solutions have been derived to predict the stress in the cohesive layer when considering the deformation in the stiff substrate. A two-dimensional cohesive layer constitutive model with a prescribed traction-separation (stress-strain) law was constructed using a modified Williams' approach, and analytical solutions derived for the elastic zone as well as the damage zone. Detailed benchmark comparisons of analytical results with finite element predictions for a double cantilever beam specimen were performed for model verification, and issues related to cohesive layer thickness were investigated. It was observed that the assumption of a rigid substrate in analytical modelling can lead to inaccurate analytical prediction of the cohesive damage zone length.
Wood Sawdust Fibres as a Secondary Filler in Carbon Black Filled NR Vulcanizates
Authors: Sombatsompop N. , Wimolmala C. Kantala and E.
Published: September 2018

Studies into the properties of polymer-wood composites (PWC) are mostly focused on thermoplastics as the matrix phase and wood flour as a reinforcing phase. This article aims to identify the optimum contents of wood sawdust fibre and silane coupling agent to be introduced into natural rubber (NR) compounded with carbon black (CB). The authors have considered a wide range of composite properties, including cure characteristics, % bound rubber, crosslink density, sorption and desorption behaviour, tensile modulus, elongation at break, tensile and tear strengths, hardness, and morphological properties. The results suggest that the overall mechanical properties of the NR composites improved with increasing CB content, but deteriorated sharply with sawdust content up to 40 phr. Addition of further sawdust was recommended as an economical benefit to industries as the properties of the NR/CB composites remained unchanged with increasing sawdust content above 40 phr sawdust fibre.

Addition of N-(βaminoethyl)-γ-aminopropyl-trimethoxy silane coupling agent to the NR vulcanisates, containing 40 phr of wood sawdust fibres and 45 phr carbon black at 0.5-1.0 %wt of wood sawdust, improved the mechanical properties. The explanations for the results given in this paper are unique in that they refer to bound rubber, crosslink density and rubber-filler phase continuity in the composites, and to a change in composite rigidity.
Effect of Interfacial Modification on the Rheological Properties and Nucleation Behaviour of PP-BaSO4 Composites
Authors: Wang Ke , Wu Jingshen , Zeng Hanmin
Published: September 2018

Polypropylene-barium sulfate (PP-BaSO4) composites were prepared by pretreating the filler with stearic acid, silane and polypropylene-g-maleic anhydride, respectively. The effects of the PP-BaSO4 interfacial interaction on the rheological properties and nucleation behaviour of the composites were studied. Surface treatment with reactive coupling agents enhanced the matrix-filler interfacial interaction and caused an increase in the melt viscosity, whereas the use of non-reactive coupling agents reduced the particle-particle interaction and led to a decrease in melt viscosity. The plain BaSO4 had a weak nucleating effect on PP. When the PP-BaSO4 interaction was enhanced, a remarkable increase in nucleation activity of the filler was observed. It is suggested that the enhanced adsorption of PP molecules onto the BaSO4 surface is of benefit in lowering the thermodynamic potential barrier for the formation of primary nuclei.
Sintering of Non-Spherical Polyethylene Particles
Authors: Torres F.G. , Cubillas M.L. , Quintana O.A.
Published: September 2018

Experimental observations of polymer sintering with non-spherical particles have been carried out. The evolution of neck formation during sintering was studied by two- particle experiments in a temperature-controlled oven. Shrinkage and change in surface area were also measured using image analysis. Melt densification studies using powder particles were included to complement the two-particle experiments. It was found that ground polymer particles show an important shape recovery stage at the beginning of the sintering process. Comparisons with sintering models available in the literature were made and deviations from the behaviour predicted by such models are discussed.
Properties of Aluminum Filled Polypropylene Composites
Authors: Osman A.F. , Mariatti M.
Published: September 2018

Polymers and metals have a long history of use in diverse applications. Metal filled polymer composites are nothing new, as the first attempt to combine these two classes of materials was made in the earlier years of the 20th century. The composites made by incorporation of powdery metal fillers into thermoplastic polymers combine the advantageous properties of metals and plastics. They offer light weight, resistance to corrosion, rapid fabrication rates and a wide range of moduli etc. In the present study, aluminum filled polypropylene (PP) composites with different filler particle shapes and filler loadings varying from 0% to 55% by volume were prepared. The effect of filler loadings and filler particle shapes on the properties of the composites was identified. The percolation concentrations were between 15% and 30% by volume for flaky aluminium filled PP composites, whereas with spherical aluminium particles the percolation concentrations were between 30% and 45% by volume.

A steep decrease in electrical resistivity and a pronounced decrease in tensile strength and elongation at break on addition of the metal filler occurred for all investigated systems. Thermal characterization studies showed that the addition of aluminium reduced the crystallinity of the polypropylene and slightly retarded its thermal degradation. High void levels must be taken into account in evaluating the results.
Preparation and Characterisation of Polyethylene-Octene Grafted Maleic Anhydride-Toughened 70:30 PA6/PP/MMT Nanocomposites
Authors: Othman Norhayani , Hassan Azman , Rahmat Abdul Razak , Wahit Mat Uzir
Published: September 2018

A series of nanocomposites consisting of a polyamide 6 (PA6) and polypropylene (PP) matrix (70:30) with a maleated polyethylene-octene elastomer (POEgMAH) and organophilic modified montmorillonite (MMT) were prepared by melt compounding in a co-rotating twin-screw extruder followed by injection moulding. The weight fraction of organoclay was adjusted from 2 – 10 wt% by increments of 2 wt% and the weight fraction of POEgMAH was fixed at 10 wt%. POEgMAH was used as an impact modifier as well as compatibiliser in the nanocomposites. Mechanical properties of the blends were investigated by tensile, flexural and impact testing. X-ray diffraction (XRD) was used to characterise the nanocomposites. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Addition of 4 wt% organoclay showed the highest tensile and flexural strengths for the blends. The Young's and flexural moduli were also improved with increasing the organoclay concentration but with a corresponding reduction in impact strength and elongation at break. XRD result revealed that the organoclay was dispersed uniformly (exfoliated) although the degree of exfoliation decreased with increasing organoclay content. The DSC analysis showed that the crystallinity of the blends decreased with increasing organoclay concentration. It was shown from the TGA analysis that the thermal stability of the PA6/PP nanocomposites was significantly improved in the presence of impermeable silicate layers in the blends.
Silane Functionalized Ethylene/Diene Copolymer Modifiers in Composites of Heterophasic Polypropylene and Microsilica
Authors: Lipponen S. , Pietikäinen P. , Vainio U. , Serimaa R. , Seppälä J.V.
Published: September 2018

Ethylene/1,7-octadiene copolymer was polymerised with metallocene catalyst and hydrosilylated to form silane functionalised polyethylenes (PE-co-SiX, X=Cl, OEt, Ph). The functionalised species were tested as modifiers in composites of rubber toughened polypropylene (heterophasic PP, hPP) and microsilica filler (μSi). A metallocene-based functionalised PE (PE-co-SiF) produced earlier in our laboratory and three commercial grades of functionalised polyolefins (one PE- and two PP-based) were used as reference modifiers. Major differences were seen in the toughness of the composites both above and below the glass transition temperature (Tg) of PP. In addition to increasing the stiffness, the microsilica filler enhanced the toughness of the heterophasic polypropylene by over 200% at ambient temperature. Below the Tg of PP (at −20 °C), the influence of μSi was the opposite and the impact strength of the hPP/μSi composite was below that of unfilled hPP. With the addition of just 2 wt% of functionalised polyethylene, the poor cold toughness of hPP/μSi composite was improved by nearly 100%. With the same addition, the toughness of the composites at ambient temperature was improved by 50 to 100% compared with the unfilled hPP. This behaviour was explained by significant changes in the fracture mechanism. Addition of functionalised PE increased the concentration of microsilica in the rubbery phase, allowing the crack to enter that phase. The rubbery phase was also able to absorb a large amount of impact energy below the glass transition temperature of PP.
Gelation Crystallization of Poly(L-Lactide) in Solvents of Varying Molecular Size
Authors: Hao Hong , Liang Guozheng , Zhao Junmin
Published: September 2018

The crystallization behaviour of poly(L-lactide) (PLLA) samples prepared in large-molecule solvents, such as poly(ethylene glycol) (PEG), was studied by differential scanning calorimetry (DSC) and X-ray diffraction. The results indicate that those samples recovered from large-molecule solvents exhibit higher crystallinity, non-isothermal crystallization temperature and faster crystallization rate than the ones crystallized in a small-molecule solvent. The crystallinity of samples from PLLA/PEG gel is about 73% measured by the DSC. The molar size of the solvent has a large influence on the formation of helical conformations and, thereby on the crystallization rate of PLLA in solution.
Analysis of Most Probable Mechanism Functions and Thermal Degradation Kinetics of N-Phenylmaleimide-Styrene-Maleic Copolymers
Authors: Zhai-min Wang , Pi-hui Pi , Xiu-fang Wen , Jiang Cheng , Zhuo-ru Yang
Published: September 2018

The thermal degradation kinetics of N-phenylmaleimide-styrene-maleic (NSMA) anhydride copolymers was analysed by a non-isothermal kinetic method. Kinetic parameters were obtained using integral and differential methods, and the most probable mechanism functions and kinetic compensation effects were discussed. The activation energy E for the thermal degradation of NSMA was 211.34kJ/mol according to the Flynn-Wall-Ozawa method and the thermal degradation was a first-order chemical reaction. A recommended rate expression for the thermal degradation reaction of NSMA was [Formula: see text] (where α is the conversion, t is time, R is the gas constant, T is the temperature and A is the pre-exponential factor), and the mathematical expressions of compensation effects for the integral and differential methods were lnA=-1.8037+0.1749E and lnA=-2.1974+0.1741E respectively.
Evaluation of the Compressive Yield Strength of Hollow Glass Microsphere – Epoxy Composites as a Function of the Microsphere/ Epoxy Interface Strength
Authors: d'Almeida J.R.M.
Published: September 2018

The compressive yield strength of glass microsphere – epoxy composites was evaluated as a function of the interface strength. The behaviour of composites with microspheres without any surface treatment was compared with that of composites fabricated with silane-treated and silicone oil-treated microspheres. Varying the hardener-to-epoxy ratio of the matrix also modified the interface. The results were compared with those derived from theoretical models, and it was shown that for hollow glass microsphere composites the effect of surface treatment can be quantitatively described using extant models. Changes in the reinforcing effect and stress concentration factor caused by the presence of the microspheres are discussed, and the experimental results explained.
Influence of Citric Acid on the Properties of Glycerol-Plasticised Cornstarch Extrusion Blends
Authors: Ning Wang , Jiugao Yu , Chunmei Han
Published: September 2018

Melt extrusion was used to prepare glycerol-plasticised dry thermoplastic starch (DTPS) in a single-screw extruder. Glycerol combined with water-plasticised starch (TPS) was studied as a standard. Citric acid (CA) was used to accelerate the plasticization of DTPS. Scanning electron microscopy revealed that residual granules existed in DTPS and the plasticisation of DTPS could be enhanced by CA. Rheological studies proved that CA decreases the shear viscosity and improves the fluidity of TPS and DTPS. It was also proved by Fourier transform infrared spectroscopy that starch and glycerol could form strong hydrogen bonds in the presence of CA. With increasing CA content, the rigid and fragile DTPS materials became more flexible, with a high tensile strength. Dynamic mechanical thermal analysis proved that CA could decrease the glass transition temperature of TPS and increase the interaction between glycerol and starch. Finally, the water absorption of DTPS and TPS were also measured.
Nir Spectroscopy: A Useful Tool for Quality Control of Glass/Phenolic Prepreg Manufacture
Authors: Li Wei , Huang Yu Dong , Chen Ping
Published: September 2018

Quality control of prepreg during production is a major emphasis in the polymer composite industry. A technique to control the quality of glass/phenolic prepreg cloth by near-infrared (NIR) spectroscopy has been successfully developed. Calibration models for the resin content, volatile content, and degree of pre-cure of the resin were created respectively by performing partial least square regression. Several spectral pretreatments were tested to obtain the optimum models. NIR prediction results showed good correlation with those from the standard method. After validation, the method was applied in the product line to investigate the relationship between these three factors and various processing parameters. Using the on-line monitoring results, quality control was realised by adjusting the appropriate processing parameters.
Bond Properties of Glass Fibre-Reinforced Polymer Dowel Bars in Jointed Concrete
Authors: Park Chan-Gi , Jang Chang-Il , Lee Sang-Woo , Won Jong-Pil
Published: September 2018

Dowel bars installed at the transverse joints of concrete slabs reduce the deflection and stress at the joint edges while transferring the traffic load from one slab to the next. We used draw-out and push-back tests to simulate the movement of a glass fibre-reinforced polymer (GFRP) dowel bar installed in a horizontal linear section of a concrete pavement undergoing repeated shrinkage and expansion movements. The tests were carried out on three different sizes and shapes of dowel bar.

The pull-out strength was lower in GFRP dowel bars with an elliptical cross section, which would be a better fit as a load transfer device in concrete pavement. Since they do not restrict shrinkage and expansion of concrete pavement and allows free movement, they would prevent destruction of a concrete slab by curling.
Lead-Free Stabilization for Pvc Pipes: The New Alternative
Authors: Hebrard Muriel , Lundquist Eric G. , Cho Jian-Yang
Published: September 2018

PVC remains the material of choice for the construction industry and pipe producers. However, environmental concern and regulations will lead to the elimination of lead based heat stabilizers over the next five years. This move to lead free stabilizers will cause pipe producers to re-evaluate their stabilizer options as they strive to keep the cost competitiveness of their PVC formulations. Thus, the challenge for stabilizer manufacturers is to propose new lead-free stabilizers for pipes with good performance and attractive costs.

Rohm and Haas Company has developed a new stabilization system that is based on a derivative of the mercaptan chemistry which has been used for decades with conventional tin stabilizers. The patented technology includes organic based, heavy metal free compositions that contain blocked thiols, which under vinyl processing conditions, generate highly active stabilizing components.

These innovative systems offer wide processing windows, give excellent early color, and can be adjusted to meet the various technical requirements of the pipe market. The stabilizing systems are odor free, and are compatible with all standard stabilizer systems. Additional benefits include reduced cross-linking leading to easier recycling. This new stabilizing systems are non toxic, contain no heavy metals, and are available as stabilizer system additives or as one-packs, offering excellent price/performance ratio.

Here we present information detailing the stabilization mechanism and performance attributes (stabilization, rheology, and recycling data) on laboratory and industrial equipment.
Eco-Composites of Polyurethane and Luffa Aegyptiaca Modified by Mercerisation and Benzylation
Authors: Melo Breno N. , dos-Santos Cláudio G. , Botaro Vagner R. , Pasa Vânya M. D.
Published: September 2018

New eco-composites were prepared from castor oil polyurethane reinforced with Luffa cylindrica fibres. These fibres were used without treatment as well as after mercerisation and mercerisation/benzylation surface treatments. TG curves of mercerised Luffa showed a small increase in thermal stability, associated with the removal of polyoses and soluble lignin. TG curves of benzylated fibres showed a decrease in thermal stability (Tonset and Tmax.) and an increase in residual carbon due to aromatic ring insertion. FTIR spectra and elemental analysis also confirmed benzylation, and X-ray diffractograms showed a decrease in cellulose crystallinity. The eco-composite (crude fibre) absorbed more water (14% after 4 – weeks' exposure) than the resin, because of the hydrophilic character of natural fibres, but mercerisation and benzylation reduced this value by about 50%. Tensile moduli of composites reinforced with untreated and mercerised fibres were comparable, but increased by 33% with the use of mercerised/benzylated Luffa cylindrica. SEMs of the fibres and fibres-matrix interfaces are presented.
Storage Stability of Ultraviolet Irradiated Hdpe
Authors: Deng Shushan , Ran Qianping , Wu Shishan , Shen Jian
Published: September 2018

The persistence of oxygen-containing groups such as C-O and C=O of ultraviolet irradiated high density polyethylene (HDPE) was investigated by FTIR, water contact angle measurement and measurements of the mechanical properties. The oxygen-containing groups of the irradiated HDPE after storage were still C=O and C-O, and the C=O concentration increased a little compared with that of the irradiated HDPE before storage. The water contact angle of the irradiated HDPE was unchanged after storage, so the hydrophilicity was constant. Compatibilised blends were prepared by using irradiated HDPE as a compatibiliser in HDPE/sericite-tridymite-cristobalite. The compatibilisation effect of the irradiated HDPE was better after storage.
Permeation of Chlorinated Hydrocarbon Vapours through Poly(Ethylene-Co-Vinyl Acetate) Membranes
Authors: Kumar S. Anil , Muralidharan M. N. , Kumaran M. G. , Thomas Sabu
Published: September 2018

The permeation of chlorinated hydrocarbon vapours through uncrosslinked and crosslinked poly(ethylene-co-vinyl acetate) (EVA) membranes has been analysed. EVA was crosslinked by dicumyl peroxide and benzoyl peroxide. The uncrosslinked sample showed a lower permeation coefficient due to its crystalline nature. The crystalline nature was supported by X-ray diffraction analysis. The differences in the permeation behaviour of the two crosslinked samples were correlated with crosslink density. Crosslink density was calculated using the equilibrium sorption method. The permeation behaviour is also supported by differential scanning calorimetry. The influence of the crosslink density and the size of penetrants on permeation was analysed. The effect of free volume on the gas barrier properties was investigated by positron annihilation lifetime spectroscopy (PALS).
Tensile and Flexural Properties of Glass-Fibre-Reinforced Cyanate Ester Syntactic Foams
Authors: John Bibin , Nair C.P. Reghunadhan , Ninan K.N.
Published: September 2018

In this paper, an attempt has been made to improve the tensile and flexural properties of cyanate ester syntactic foams by glass-fibre reinforcement. Cyanate ester syntactic foams with varying glass-fibre reinforcements were processed and evaluated for tensile and flexural properties. The effect of concentration and length of fibre on these mechanical properties was investigated. In one approach, the concentration of fibre was varied (5–20 wt.%) and the length of fibre was fixed at 5 mm. Tensile and flexural strength increased with fibre concentration, reached a maximum at a fibre concentration of 16.6 wt.%, and decreased on further addition. The diminution in strength beyond a fibre concentration of 16.6 wt.% was ascribed to the poor wetting of fibre by resin, which leads to an easy pull-out of fibres. In another study, the fibre length was varied (5–25 mm) and the ‘cyanate ester:microballoon:glass fibre’ ratio (1:1:0.5 by weight) was kept constant. A fibre length of 20 mm gives the optimum tensile and flexural properties. Considerable improvement in tensile and flexural properties of cyanate ester syntactic foams was achieved by glass-fibre reinforcement. A scanning electron microscopic study was performed on failed samples to substantiate the observed trends in the mechanical properties.