Book•
Mechanical Properties of Polymers and Composites
14 Dec 1993-
TL;DR: In this article, the authors discuss various mechanical properties of fiber-filled composites, such as elastic moduli, creep and stress relaxation, and other mechanical properties such as stress-strain behavior and strength.
Abstract: Mechanical Tests and Polymer Transitions * Elastic Moduli * Creep and Stress Relaxation * Dynamical Mechanical Properties * Stress-Strain Behaviour and Strength * Other mechanical Properties * Particulate-Filled Polymers * Fiber- Filled Composites and Other Composites.
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Journal Article•
TL;DR: In this article, the authors show that the damping ability of polyurethanes can be improved by adding titanium dioxide (TiO2) into the polymer. But, they do not consider the effect of UV-induced aging.
Abstract: Polyurethanes (PUs) have been synthesised successfully from renewable resources namely as rapeseed and sunflower oil using 4,4’-methylen-bis-(phenylisocyanate) (MDI) as the cross-linking agent. The mechanical property of these materials was observed in the Dynamic Mechanical Thermal Analysis (DMTA) test. A high tan delta peak is essential for a good damping material. These PUs can be strongly influenced on the addition of small (2.5-10) percentages of titanium dioxide, TiO2, e.g. the damping was improved on adding TiO2. Upon UV-induced aging, two important changes occur as observed in mechanical damping, such as a decrease in the height of the tan delta peak and a shift of the temperature of the tan delta peak to higher values with increased irradiation time. The loss tan delta peaks for the rapeseed-based PU loaded with 2.5, 5, 7.5, 10% of TiO2 were 0.58, 0.6, 0.68, and 0.71 respectively as compared with neat RSPU at only 0.43. These data show that the damping ability is enhanced through the introduction of TiO2 into the polymer. By doping with TiO2, the mechanical or physical properties of these PUs can be altered systematically, such as to get progressive increases in its stiffness and damping property.
30 citations
Cites background from "Mechanical Properties of Polymers a..."
...Cross-linking influences the mechanical properties of polyurethanes [13,16-19]....
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...1), based on the rubber elasticity [12-15]: E’ = 3 veRT (3....
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TL;DR: In this paper, the applicability of the Tsai-Hill equation to a polymer-polymer microfibril reinforced composite (MFC), in which the reinforcing elements represented micro-fibrils with a diameter around 1-3 μm and aspect ratio of about 100, was investigated.
Abstract: While the main goal of the first part of this study was to check the applicability of the Tsai–Hill equation to a polymer-polymer microfibril reinforced composite (MFC), in which the reinforcing elements represented microfibrils with a diameter around 1–3 μm and aspect ratio of about 100, in the present paper a similar goal involves the Halpin–Tsai equation. In addition, using compatibilised blends an attempt is made to shed light on the mechanism of the microfibril formation during drawing of isotropic polymer blends. For this purpose, injection moulded dog-bone test samples of blends of polypropylene/poly(ethylene terephthalate) (PP/PET) (60/40 wt%) have been prepared starting from highly drawn bristles, also from blends containing 0–9 wt% compatibiliser (ethylene-glycidyl methacrylate). The MFC structure of the test sample is established by X-ray and scanning electron microscope (SEM) analyses. The tensile data are compared with those predicted according to the Halpin–Tsai equation. It is shown that th...
30 citations
TL;DR: The modified Lewis-Nielsen equation was developed using the effective fiber length factor to accurately predict the modulus of the short fiber reinforced composites, and validated with experimental results.
Abstract: The influence of interfacial shear strength (IFSS) between processed short S-glass fibers (250 and 350 μm in length, 5 μm in diameter) and the dental resin (a mixture of urethane dimethacrylate and triethylene glycol dimethacrylate monomers) on the mechanical properties has been studied experimentally. The surface profile of short S-glass fibers was modified using a selective atomic level metal etching process and simple silanization process to enhance the interfacial properties. The S-glass fibers were etched in acid solutions to increase the surface roughness and selectively remove Al3+ and Mg2+ ions, which promoted the mechanical and chemical interfacial bonding reactions. The single glass fiber tensile and microdroplet pull-out tests were performed to investigate the effects of interfacial properties on the flexural strength of the resultant composites. The surface modified S-glass fibers showed an increase of 11-40% in IFSS compared to untreated glass fibers. Composites reinforced with 350 μm length glass fibers (AR-70), which were treated in piranha solution for 4 h, showed the highest improvement in overall mechanical properties, flexural strength (34.2%), modulus (9.7%), and breaking energy (51.9%), compared to the untreated fiber-reinforced composites. The modified Lewis-Nielsen equation was developed using the effective fiber length factor to accurately predict the modulus of the short fiber-reinforced composites and validated with experimental results.
30 citations
TL;DR: In this article, the miscibility of melt processed blends of bacterial poly(3-hydroxybutyrate) (PHB) with poly(epichlorohydrin) (PEC) was investigated over the whole range of compositions by means of differential scanning calorimetry, dynamic-mechanical analysis, and hot-stage optical microscopy.
Abstract: The miscibility of melt processed blends of bacterial poly(3-hydroxybutyrate) (PHB) with poly(epichlorohydrin) (PEC) is investigated over the whole range of compositions by means of differential scanning calorimetry, dynamic-mechanical analysis, and hot-stage optical microscopy. PHB and PEC are miscible in the melt in all proportions. After melt quenching, PHB/PEC blends show a single glass transition that linearly changes with composition between the T gs of the pure components (PHB = 2°C, PEC = −21°C). At room temperature all PHB/PEC blends are partially crystalline, owing to crystallization of a constant fraction (58%) of the PHB present in each blend. A spacefilling spherulitic morphology develops upon blend crystallization from the melt. Isothermal crystallization measurements show that over the range of crystallization temperatures (40°C < T e < 130°C) and compositions (20% < PEC < 80%) explored, the spherulite radial growth rate (G) decreases with increasing PEC content. Biodegradation exp...
30 citations
TL;DR: In this article, a texture analyzer was used to measure the adhesion performance of acrylic pressure sensitive adhesives (PSAs) in order to identify the flexibility and recovery of the acrylic PSAs.
Abstract: Acrylic pressure sensitive adhesives (PSAs) are used in the production of flexible displays. Acrylic PSAs must have high flexibility and recovery to meet the industry demands for flexible displays. For these reasons, acrylic PSAs were designed to determine the effects of molecular weight and cross-linking on acrylic PSAs. Stress relaxation and creep tests were measured with dynamic mechanical analysis to identify the flexibility and recovery of the acrylic PSAs. The molecular weight and glass transition temperature of the PSAs were measured by gel permeation chromatography and differential scanning calorimetry. A texture analyzer was used to measure the adhesion performance of the acrylic PSAs. With increasing molecular weight, the adhesion performance increased, especially from 86 to 108 K molecular weight PSAs. This is due to the entanglement of the polymer chains. The stress and recovery of cross-linked acrylic PSAs was much higher than that of neat acrylic PSAs. This result is attributed to in...
30 citations
Cites background from "Mechanical Properties of Polymers a..."
...[5–8] An increase in the chain length of higher molecular weight polymers increases the glass transition temperature (Tg) and viscosity and affects the wetting, adhesion, and cohesion properties of the adhesive.[5,6,9] Various polymers have been studied, for example, poly(vinyl alcohol),[10,11] epoxidized natural rubber,[12–14] and poly (isobutylene),[15] all of which have been studied with regard to the influence of molecular weight upon adhesion....
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