Polymer Journals

Polymers and Polymer Composites

Logged into APC, CP, IPSAT, PPC, PRR, RRR & PRPRT.

Back  Search



Title: Analytical modelling of textile parameters and draping behaviour of 2D biaxial braided sleevings
Page Range: p.315-326
Author(s): Schillfahrt C; Schledjewski R
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
Biaxial braided sleevings are commonly used for producing hollow complex-shaped composite parts through bladder inflation moulding. To enable feasibility analyses, part design and the prediction of mechanical properties of the resulting fibre-reinforced component, various geometrical and weight-related parameters of the braided fabric in its draped state must be known, such as fibre orientation, fibre volume fraction and areal weight. In the present work, a comprehensive analytical model describing fabric formation, preform architecture and weight as well as the change of relevant textile parameters of a biaxial braided sleeving during draping is established. The principal modelling approach is based on sporadic investigations found in literature and was substantially expanded to compile an extensive collection of relationships for the utilisation in a sleeving-on preforming process. Furthermore, a critical overview about the state of the art in the area of geometrical modelling of tubular 2D braided structures and a comparison of the identified procedures in regard to the desired application is given. 43 Refs.

Title: UV effects on the tensile and creep behaviour of HDPE
Page Range: p.327-332
Author(s): Becerra A F C; d'Almeida J R M
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
The tensile and creep behaviour of a high-density polyethylene grade used to manufacture pipes were evaluated as a function of the time of exposure to UV radiation. The effect of the creep stress level was also analysed. A threshold radiation dose was determined, above which UV radiation causes loss of the macroscopic mechanical behaviour for this particular HDPE grade. Below the threshold value, macromolecular modifications were also taking place, but the deleterious effect of UV radiation was masked by the development of a more rigid structure. Scanning electron microscopy, melt flow index and thermogravimetric analysis were used to support the results of the mechanical analysis. 17 Refs.

Title: Behaviour of hybrid SiC/jute epoxy composites manufactured by vacuum assisted resin infusion
Page Range: p.333-344
Author(s): Noha Ramadan; Iman Taha; Rawia Hammouda; Abdellatif M H
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
Natural fibre-reinforced polymer composites are standing in the limelight of investigations due to their light weight and availability from natural and renewable resources. Improved mechanical and physical behaviour is targeted through hybridisation with other reinforcing elements. This study investigates the potential of adding silicon carbide particles at volume contents ranging between 2 and 8% to jute fabric-reinforced epoxy composite to produce such hybrid composites. In contrast to the commonly applied processing technique of hand layup used to produce natural fibre-reinforced laminates, the vacuum-assisted resin infusion method was applied in this study to produce high quality laminates. Samples were tested for their mechanical behaviour through tensile, flexural and impact tests. Scanning electron microscopy was further performed to analyse the modes of failure of the composites. Finally, erosion tests were conducted, by directly sanding the hybrid composite samples to evaluate their erosion wear resistance. Results indicated that the addition of particles had a significant effect on the tensile, flexural, impact and erosion wear behaviour of the composites under investigation. Hybrid composites reinforced with 4 vol.% SiC exhibited acceptable mechanical properties. The behaviour was found to deteriorate at SiC contents beyond 4 vol.%. 32 Refs.

Title: Synthesis and characterisation of novel thiophene based azomethine polymers and study of their liquid crystalline, electrochemical and optoelectronic properties
Page Range: p.345-362
Author(s): Omer Yasin Al-Janabi; Foot P J S; Emaad Taha Al-Tikrity; Spearman P
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
This work reports the synthesis, structural characterisation, liquid crystallinity, luminescence and electroluminescence of novel thiophene azomethine polymers. The polymers under study were prepared via oxidative polymerisation of four novel monomers at room temperature using iron (III) chloride. The chemical structures of the prepared monomers and polymers were confirmed by infrared and 1H and 13C NMR spectroscopy. Molecular masses were determined for monomers and polymers by gas/liquid chromatography-mass spectrometry (GC/LC-MS) and by gel-permeation (size exclusion) chromatography (SEC), respectively. Thermal stability studies of the prepared materials were achieved by thermogravimetric analysis (TGA), and the onset of weight loss To and the endset Tmax were calculated from the thermograms. Liquid crystalline mesophases and phase changes of the monomers and polymers were studied by differential scanning calorimetry (DSC) and polarised optical microscopy (POM), and the glass transition temperatures Tg of the polymers were determined from the DSC curves. The electrochemical band gaps, HOMO and LUMO energy levels were measured by cyclic voltammetry. UV-visible absorption-emission spectra (liquid and solid films) of the polymers were obtained at room temperature with different solvents. Optical band gaps were calculated from the absorption edges, and were in good agreement with those estimated from cyclic voltammetry. Mixing the polymers with lanthanide salts such as EuCl3 and YbCl3 gave modified fluorescence, and the light emitted was much more intense than that from the pure polymers. Polymer based light-emitting diodes (PLEDs) were fabricated by spin coating, and their current-voltage characteristics were measured. In preliminary work, the polymer devices were found to produce electroluminescent spectra similar to the PL spectra of the corresponding samples. Molecular modelling studies were performed both on polymer segments and monomer molecules; the absorption spectra of the prepared polymers, HOMO and LUMO energy levels were calculated with ZINDO using AMI geometry optimisation. 25 Refs.

Title: Vinyl ester resin modified with acrylated epoxidised soybean (AESO) and linseed (AELO) oils: effect of additional urethane crosslinking
Page Range: p.363-370
Author(s): Grishchuk S; Karger-Kocsis J
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
Bisphenol A-based vinyl ester resin (VE) was modified with acrylated epoxidised soybean and linseed oils (AESO and AELO, respectively) in 10 wt.%. The double bond/epoxy ratio in these functionalised vegetable oils was practically the same, i.e. 30/70%, allowing us to deduce effects caused by the different unsaturations in the parent oils. The crosslink density of the resins was enhanced by adding polyisocyanate. The glass transition temperature (Tg) of the hybrids was determined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Resistance to thermal degradation was assessed by thermogravimetric analysis (TGA). The fracture toughness and energy (Kc and Gc, respectively) were determined on compact tension specimens at room temperature. Incorporation of AESO and AELO reduced the Tg of VE along with slight reductions in the Kc and Gc data. The Tg reduction was less for AELO than AESO which was attributed to the higher functionality of AELO compared to AESO. Urethane crosslinking of VE (VEUH) prominently enhanced the Tg. Modification of VEUH with AES(L)O enhanced the Tg due to additional crosslinks. Urethane hybridisation was associated with a strong decrease in both Kc and Gc compared to those of the parent VE. Kc and Gc of VEUH did not change practically as a function of blending with AES(L)O. Incorporation of AES(L)O reduced the resistance to thermal degradation of both VE and VEUH. 36 Refs.

Title: Detection of Voids in Carbon/Epoxy Laminates and Their Influence on Mechanical Properties
Page Range: p.371-380
Author(s): Di Landro L; Montalto A; Bettini P; Guerra S; Montagnoli F; Rigamonti M
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
Defects, such as voids and delaminations, may significantly reduce the mechanical performance of components made of composite laminates. Distributed voids and porosity are generated during composite processing and are influenced by prepreg characteristics as well as by curing cycle parameters. On the basis of rheological and thermal analyses, as well as observations of laminates produced by different processing conditions, curing pressure appears the most influent factor affecting the void content. This work compares different methods for void analysis and quantitative evaluation (ultrasonic scan, micro-computed tomography, acid digestion, SEM image analysis) evidencing their applicative limitations. Carbon/epoxy laminates were produced in autoclave or oven by vacuum bag technique, using different processing conditions, so that void contents ranging from 0% to 7% volume were obtained. Effects of porosity over laminates mechanical performances are analysed. The results of tensile and compressive tests are discussed, considering the effect that different curing cycles have over void content as well as over fibre/resin fraction. Interlaminar strength, as measured by short beam shear tests, which is a matrix-dominated property, exhibits a reduction of failure strength up to 25% in laminates with the highest void content, compared to laminates with no porosity. 24 Refs.

Title: Low velocity impact behaviour of asymmetric three-layer sandwich composite structures with and without foam core
Page Range: p.381-394
Author(s): Azam Kavianiboroujeni; Cloutier A; Rodrigue D
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
This paper presents an experimental investigation of the impact behaviour of three layer sandwich structures made of high density polyethylene (HDPE) and hemp, with and without a foam core. Low-velocity falling weight and Charpy impact tests were performed to investigate the influence of hemp content, skin thickness and core density. The strength, load, absorbed energy, and deflection histories were recorded and analysed and the damaged specimens were inspected to determine the failure patterns. Based on the Charpy impact results, the structures with foam core had higher energy absorption capabilities compared to their counterparts without foam core. In addition, based on the falling weight impact results the energy dissipation properties of sandwich structures without foam core were superior to the structures with foam core. This property was also greatly influenced by skin fibre content, skin thickness and structure configuration. 36 Refs.

Title: Studies on processing rheological and mechanical properties of poly(lactic acid)/sesbania gum/nano-silica composites
Page Range: p.395-404
Author(s): Qing Zhang
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
Processing rheological properties of poly(lactic acid) (PLA)/sesbania gum (SG)/nano-silica composites were investigated with a torque rheometer, and mechanical properties were researched by a universal testing machine and a cantilever-beam impact testing machine. Effects of SG content, nano-silica content, the types of plasticisers, the plasticiser content and the rotor speed of a torque rheometer on the properties of composites were discussed. The results indicated that polyethylene glycol (PEG)20000 exhibited the best plasticising effect on the composites, and at the same time, did not increase energy consumption of the systems compared with other four plasticisers. As for the aspect of processing rheological properties, the optimum formulation for PLA/SG/ nano-SiO2/PEG20000 composites was: 100 parts of PLA, 8 parts of SG, 2 parts of nano-SiO2, and 5-10 parts of PEG20000. Comparing with unmodified PLA, the comprehensive mechanical properties of the composites improved greatly, based on the results of the tensile, impact and bending tests. 30 Refs.

Title: Isocyanate-functionalised montmorillonite as a reactive asphalt modifier
Page Range: p.405-418
Author(s): Dengke Zhang; Xinyan Xiao; Ying Cui
File size:
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 25
Issue No: No.5

Abstract
Sodium montmorillonite was functionalised by isophorone diisocyanate (IPDI) and organic montmorillonite was functionalised by hydrogenated diphenylmethane diisocyanate (HMDI). Reaction between montmorillonite (MMT) and IPDI/HMDI caused the interlayer space of MMT to increase from 1.41 nm to 1.95 nm and 2.08 nm to 2.42 nm, respectively, and the resulting grafted -NCO groups led to a suitable reactive modifier. In order to improve the high-temperature performance and UV ageing resistance of the asphalt binder, asphalt modification was carried out by chemical reaction between -NCO groups and some polar groups (mainly -OH) of asphalt. The results showed that the interlayer space enlarged and exfoliated structure was formed due to the introduction of functionalised MMT (IPDI-HMMT-85 or HMDI-OMMT-80) into the asphalt. The as-prepared IPDI-HMMT-85 and HMDI-OMMT-80 modified asphalts, with a maximum softening point of 57.0 5C and 62.2 CC, initial decomposition temperature of 363 CC and 374 CC, respectively, possessed good storage stability, and were superior to Na-MMT modified asphalt and OMMT modified asphalt in terms of high temperature and UV ageing properties. 39 Refs.

%>