scholarly journals Studies on Structures and Dynamic Properties of Peroxide-Crosslinked EPDMs, Part 5: Relation of Storage Modulus to Crosslinking Density and Molecular Mobility

2006 ◽  
Vol 79 (12) ◽  
pp. 551-556 ◽  
Author(s):  
Hitoshi IWABUKI ◽  
Kazuya NAGATA ◽  
Toru NOGUCHI ◽  
Eisuke YAMADA
Keyword(s):  
Storage Modulus ◽  
Molecular Mobility ◽  
Dynamic Properties ◽  
Crosslinking Density

The Effect of Compositional and Testing Variations on the Dynamic Properties of Compounds Based on Styrene-Butadiene and Polybutadiene Elastomers

1971 ◽  
Vol 44 (1) ◽  
pp. 258-270 ◽  
Author(s):  
D. A. Meyer ◽  
J. G. Sommer
Keyword(s):  
Carbon Black ◽  
Storage Modulus ◽  
Dynamic Properties ◽  
Loss Modulus ◽  
Dynamic Stiffness ◽  
Rate Of Change ◽  
Complex Dynamic ◽  
Spring Rate ◽  
Styrene Butadiene ◽  
Black Level

Abstract Important factors of potential use for manipulating static and dynamic stiffness and the damping characteristics of compounds based on styrene-butadiene and polybutadiene elastomers and their blends have been outlined. Their characteristics have been compared with those of IIR and EPDM compounds. The effects of variations in composition are quantitatively defined to assist the compounder in combining these effects in a manner that will lead to a desired combination of properties. In addition to the expected increase in static spring rate and dynamic spring rate with carbon black level, the following responses to compositional variations were found important: 1. The complex dynamic spring rate is more sharply dependent upon carbon black level than the static spring rate. 2. The complex dynamic spring rate is essentially independent of the level of crosslinking while static spring rate increases. 3. Damping coefficient is directly proportional to the level of carbon black and inversely proportional to the level of crosslinking. 4. Styrene level in a polymer blend and plasticizer composition can be used to adjust loss modulus and storage modulus at a given temperature and also to modify the rate of change of these properties with temperature. 5. The strain dependency of storage modulus was found in one instance to vary with the elastomer composition. The IIR vulcanizate, when formulated to the same static modulus, exhibited a larger strain dependence than the SBR, BR, and EPDM composition.

Effect of Sulfur Donor on Properties of Thermoplastic Vulcanizates Based on NR/PP

2012 ◽  
Vol 626 ◽  
pp. 54-57 ◽  
Author(s):  
Chanida Manleh ◽  
Charoen Nakason ◽  
Natinee Lopattananon ◽  
Azizon Kaesaman
Keyword(s):  
Storage Modulus ◽  
Crosslink Density ◽  
Dynamic Properties ◽  
Complex Viscosity ◽  
Melt Mixing ◽  
Dynamic Vulcanization ◽  
Thermoplastic Vulcanizates ◽  
Pp Blends ◽  
Thermal Stability Of ◽  
Sulfur Donor

Thermoplastic vulcanizates based on natural rubber and polypropylene blend (NR/PP) was prepared via dynamic vulcanization by melt mixing process at 180°C and a rotor speed of 60 rpm. Three types of vulcanizing agent (i.e., Tetramethyl thiuram disulfide (TMTD), 4,4 Dithiodimorpholine (DTDM) and Dipentamethylene thiuram tetrasulfide (Tetrone A)) were used to cure the rubber phase of NR/PP blends. Influence loading levels of sulfur donor at 1, 2 and 3 phr on dynamic properties and crosslink density were studied. The result showed that the dynamically cured NR/PP blends with Tetrone A gave higher mechanical properties, storage modulus, complex viscosity, and crosslink density with the lower value of tanδ than those of the blends with TMTD and DTDM. Furthermore, the storage modulus, complex viscosity and crosslink density of TPVs increased with increasing loading levels for all types of sulfur donor. It was also found that thermal stability of dynamically cured NR/PP blends is higher than that of the pure NR.

Electrospun Polymer/MWCNTs Nanofiber Reinforced Composites “Improvement of Interfacial Bonding by Surface Modified Nanofibers”

2009 ◽  
Vol 1224 ◽  
Author(s):  
Elif Ozden ◽  
Yusuf Ziya Menceloglu ◽  
Melih Papila
Keyword(s):  
Storage Modulus ◽  
Mechanical Response ◽  
Crosslinking Agent ◽  
Weight Fraction ◽  
Crosslinking Density ◽  
Interfacial Bonding ◽  
Reinforced Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Surface Modified ◽  
Walled Carbon Nanotubes

AbstractIn-house synthesized copolymers Polystyrene-co-glycidyl methacrylate (PSt-co-GMA) are electrospun as mat of surface modified nanofibers with and without multi walled carbon nanotubes (MWCNTs). Composites are then formed by embedding layers of the nanofiber mats into epoxy resin. Interfacial bonding between polymer matrix and the nanofibers, and surface modification driven enhancement in mechanical response is assessed under flexural loads. Results indicate that at elevated temperture storage modulus of epoxy reinforced by PSt-co-GMA nanofibers and PSt-co-GMA/ MWCNTs composite nanofibers is about 10 and 20 times higher than the neat epoxy, respectively, despite weight fraction of the nanofibers being as low as 2%. Interfacial interaction is revealed by the storage modulus comparison of unmodified Polystyrene (PSt) and modified PSt-co-GMA nanofiber reinforced composite. To enhance further the resulting “crosslinked” structure, crosslinking agent ethylenediamine is also sprayed on the nanofibrous mats. Increased crosslinking density improves mechanical response of sprayed-over PSt-co-GMA nanofibers reinforced composites which is about 4 times higher than plain PSt-co-GMA nanofibers.

scholarly journals Dynamic Properties of Tympanic Membrane in a Chinchilla Otitis Media Model Measured With Acoustic Loading

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Zachary Yokell ◽  
Xuelin Wang ◽  
Rong Z. Gan
Keyword(s):  
Tympanic Membrane ◽  
Storage Modulus ◽  
Otitis Media ◽  
Loss Factor ◽  
Dynamic Properties ◽  
Acute Otitis Media ◽  
Thickness Variation ◽  
Published Data ◽  
Fe Model ◽  
Control Samples

Otitis media is the most common infectious disease in young children, which results in changes in the thickness and mechanical properties of the tympanic membrane (TM) and induces hearing loss. However, there are no published data for the dynamic properties of the TM in otitis media ears, and it is unclear how the mechanical property changes are related to TM thickness variation. This paper reports a study of the measurement of the dynamic properties of the TM in a chinchilla acute otitis media (AOM) model using acoustic loading and laser Doppler vibrometry (LDV). AOM was created through transbullar injection of Haemophilus influenzae into the middle ear, and AOM samples were prepared 4 days after inoculation. Vibration of the TM specimen induced by acoustic loading was measured via LDV over a frequency range of 0.1–8 kHz. The experiment was then simulated in a finite element (FE) model, and the inverse-problem solving method was used to determine the complex modulus in the frequency domain. Results from 12 ears (six control and six AOM) show that the storage modulus of the TM from AOM ears was on average 53% higher than that of control ears, while the loss factor was 17.3% higher in control ears than in AOM ears at low-frequency (f < 1 kHz). At high-frequency (e.g., 8000 Hz), there was a mean 40% increase in storage modulus of the TM from AOM compared to control samples. At peak frequency (e.g., 3 kHz), there was a 19.5% increase in loss factor in control samples compared to AOM samples. These findings quantify the changes induced by AOM in the chinchilla TM, namely, a significant increase in both the storage and loss moduli.

High Frequency Viscoelasticity of Carbon Black Filled Compounds

1996 ◽  
Vol 69 (5) ◽  
pp. 786-800 ◽  
Author(s):  
M. Gerspacher ◽  
C. P. O'Farrell ◽  
L. Nikiel ◽  
H. H. Yang ◽  
F. Le Méhauté
Keyword(s):  
Carbon Black ◽  
High Frequency ◽  
Dynamic Properties ◽  
Shear Waves ◽  
Crosslinking Density ◽  
Filler Loading ◽  
Wave Measurements ◽  
Rubber Compounds ◽  
Longitudinal And Shear Waves ◽  
Laboratory Tool

Abstract A high frequency viscoelasticity spectrometer, using the state-of-the-art ultrasonic technology, was constructed. The longitudinal and shear waves characteristics were measured in rubber compounds to obtain the attenuation coefficient, α, and sound velocity, v Preliminary results were obtained for a number of filled and unfilled polymers. The grade of carbon black used, filler loading, crosslinking density and filler dispersion were varied during the study. Temperature sweepS from −100°C to +60°C were also studied. It was found that the polymer type had a greater influence on α and v than did the grade of carbon black, loading or dispersion. The experimental data show that shear waves do not propagate in the rubbery state. Above the glass transition temperature, Tg, the longitudinal wave measurements could be sufficient to determine the high frequency dynamic properties of filled and unfilled polymers to characterize a tire tread compound. The temperature sweep measurements allowed the determination of the Tg of polymers at high frequency. It is proposed that the described method of measuring α and v be used as a laboratory tool for potential tire traction prediction.

scholarly journals Lipid Composition but not Curvature Is the Determinant Factor for the Low Molecular Mobility Observed on the Membrane of Virus-Like Vesicles

Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 415 ◽  
Author(s):  
Iztok Urbančič ◽  
Juliane Brun ◽  
Dilip Shrestha ◽  
Dominic Waithe ◽  
Christian Eggeling ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Composition ◽  
Molecular Mobility ◽  
Lipid Membrane ◽  
Dynamic Properties ◽  
Super Resolution ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Membrane Composition ◽  
Hiv 1

Human Immunodeficiency Virus type-1 (HIV-1) acquires its lipid membrane from the plasma membrane of the infected cell from which it buds out. Previous studies have shown that the HIV-1 envelope is an environment of very low mobility, with the diffusion of incorporated proteins two orders of magnitude slower than in the plasma membrane. One of the reasons for this difference is thought to be the HIV-1 membrane composition that is characterised by a high degree of rigidity and lipid packing, which has, until now, been difficult to assess experimentally. To further refine the model of the molecular mobility on the HIV-1 surface, we herein investigated the relative importance of membrane composition and curvature in simplified model membrane systems, large unilamellar vesicles (LUVs) of different lipid compositions and sizes (0.1–1 µm), using super-resolution stimulated emission depletion (STED) microscopy-based fluorescence correlation spectroscopy (STED-FCS). Establishing an approach that is also applicable to measurements of molecule dynamics in virus-sized particles, we found, at least for the 0.1–1 µm sized vesicles, that the lipid composition and thus membrane rigidity, but not the curvature, play an important role in the decreased molecular mobility on the vesicles’ surface. This observation suggests that the composition of the envelope rather than the particle geometry contributes to the previously described low mobility of proteins on the HIV-1 surface. Our vesicle-based study thus provides further insight into the dynamic properties of the surface of individual HIV-1 particles, as well as paves the methodological way towards better characterisation of the properties and function of viral lipid envelopes in general.

Dynamic Mechanical Properties and Tensile Behavior of Oil Palm Ash Filled Natural Rubber Vulcanizates

2013 ◽  
Vol 844 ◽  
pp. 305-308
Author(s):  
Zhong Xian Ooi ◽  
Hanafi Ismail ◽  
Azhar Abu Bakar
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Storage Modulus ◽  
Oil Palm ◽  
Dynamic Properties ◽  
Low Cost ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical ◽  
Oil Palm Ash ◽  
Tan Δ

The potential of utilizing low cost filler, i.e. oil palm ash (OPA) as a new filler in natural rubber (NR) compounds using conventional laboratory-sized two roll mills. The NR compound was cross-linked using sulphuric system. The variations of tensile and dynamic properties were examined in the NR vulcanizates with the OPA filling at low loading. In the view of reinforcement, the tensile strength and elongation at break was improved with the low loading of OPA (<10 phr). Dynamic mechanical properties of OPA filled NR vulcanizates was investigated with respect to the storage modulus and mechanical loss factor (Tan δ). Result showed that the storage modulus of the OPA filled NR vulcanizates became higher than that of gum NR vulcanizates whereas the peak height of tan δmax was reduced as the OPA loading was increased. This phenomenon manifested a strong rubber-filler interaction with the low loading of OPA.

scholarly journals Lipid composition but not curvature is a determinant of a low molecular mobility within HIV-1 lipid envelope

2018 ◽  
Author(s):  
Iztok Urbančič ◽  
Juliane Brun ◽  
Dilip Shrestha ◽  
Dominic Waithe ◽  
Christian Eggeling ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Composition ◽  
Molecular Mobility ◽  
Lipid Membrane ◽  
Dynamic Properties ◽  
Super Resolution ◽  
Membrane Curvature ◽  
Correlation Spectroscopy ◽  
Membrane Composition ◽  
Hiv 1

AbstractHuman Immunodeficiency Virus type-1 (HIV-1) acquires its lipid membrane from the plasma membrane of the infected cell from where it buds out. Previous studies have shown that the HIV-1 envelope is a very low mobility environment with the diffusion of incorporated proteins two orders of magnitude slower than in plasma membrane. One of the reasons for this difference is thought to be due to HIV-1 membrane composition that is characterised by a high degree of rigidity and lipid packing. To further refine the model of the molecular mobility on HIV-1 surface, we here investigated the relative importance of membrane composition and curvature in Large Unilamellar Vesicles of different composition and size (0.2–1 μm) by super-resolution STED microscopy-based fluorescence correlation spectroscopy (STED-FCS) analysis. We find that lipid composition and its rigidity but not membrane curvature play an important role in the decreased molecular mobility on vesicle surface thus confirming that this factor is an essential determinant of HIV-1 low surface mobility. Our results provide further insight into the dynamic properties of the surface of individual HIV-1 particles.

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