Effect of Methacrylate Co-Agents on Peroxide Cured PP/EPDM Thermoplastic Vulcanizates

2007 ◽  
Vol 80 (1) ◽  
pp. 83-99 ◽  
Author(s):  
F. R. de Risi ◽  
J. W. M. Noordermeer
Keyword(s):  
Room Temperature ◽  
Weight Fraction ◽  
Economic Importance ◽  
Dynamic Vulcanization ◽  
Fixed Amount ◽  
Compression Set ◽  
Thermoplastic Matrix ◽  
A Value ◽  
Thermoplastic Vulcanizates ◽  
Diene Rubber

Abstract Thermoplastic vulcanizates (TPVs) have gained large technical and economic importance. TPVs are characterized by a chemically crosslinked rubber phase, embedded in a thermoplastic matrix, produced by dynamic vulcanization during mixing with the thermoplastic in its molten state. Methacrylate species are investigated as co-agents for peroxide vulcanization of polypropylene/ethylene-propylene-diene-rubber (PP/EPDM) TPVs, whereby the weight fraction of the EPDM is varied from 30, 50 to 70%. Ethylene glycol dimethacrylate (EDMA), trimethylol propane trimethacrylate (TMPTMA, often referred to as TRIM) and zinc dimethacrylate (ZDMA) are tested. A fixed amount of dicumyl peroxide as crosslinker and varying contents of co-agents are employed, the latter to boost EPDM-crosslinking and prevent degradation of the PP by β-scission. Differences observed in mechanical properties point to diverse structures of the crosslink networks of the TPVs. Of the three co-agents, TMPTMA gives the best overall balance of properties by EPDM crosslinking and preventing PP-degradation. This is explained by the positioning of the solubility parameter of this co-agent between those of EPDM and PP, whilst EDMA presents a value far away from either one. ZDMA, although giving very good room temperature properties like tensile strength, shows signs of thermo-reversion of the crosslinks in the compression set measured at 70 °C.

Processing of Thermoplastic Vulcanizates Using High Speed Intermeshing-Typed Internal Mixer: Influence of Mixing Patterns

2013 ◽  
Vol 844 ◽  
pp. 117-121 ◽  
Author(s):  
Wattana Teppinta ◽  
Banja Junhasavasdikul ◽  
Nattapong Nithi-Uthai
Keyword(s):  
High Speed ◽  
Rectangular Cross Section ◽  
Processing Condition ◽  
Compression Set ◽  
Single Screw Extruder ◽  
Thermoplastic Vulcanizates ◽  
Rubber Phase ◽  
Mixing Patterns ◽  
Internal Mixer ◽  
Diene Rubber

Thermoplastic vulcanizates (TPVs) were produced by high speed intermeshing-type internal mixer. TPVs based on Ethylene-propylene-diene rubber (EPDM) and polypropylene (PP) with peroxide crosslink system, were used in this investigation. TPVs were prepared by different processing condition using the same TPV recipes. In this study we focus on the effect of mixing pattern on TPVs properties. From the results, tensile properties and hardness of TPVs are slightly affected by processing conditions. In the same way, compression set which relate to crosslink density in rubber phase, were not affected by processing condition as well. All TPV samples were extruded to form a strip of 1 x 50 mm rectangular cross section using single screw extruder. It was found that, the stage of adding curative shows significant influence on extrudates surface of TPVs. TPV samples produced by adding the curative at low temperature show the smoothest surface. This is because the fine dispersion of crosslinked rubber phase which confirmed by AFM.

Thermoplastic Elastomers Based on PP/EPDM Blends by Dynamic Vulcanization

2007 ◽  
Vol 80 (3) ◽  
pp. 504-519 ◽  
Author(s):  
Kinsuk Naskar
Keyword(s):  
Thermoplastic Elastomers ◽  
Review Article ◽  
Dynamic Vulcanization ◽  
Phenolic Resins ◽  
Thermoplastic Vulcanizates ◽  
Different Types ◽  
Ethylene Propylene Diene Rubber ◽  
Diene Rubber ◽  
Crosslinking Agents

Abstract This review article introduces various aspects of dynamic vulcanization as applied to thermoplastic elastomers (TPEs). The classification of polymer blends and TPEs, the development of thermoplastic vulcanizates (TPVs), and the application of different types of crosslinking systems with special emphasis on peroxides/co-agents, and phenolic resins as crosslinking agents for polypropylene / ethylene propylene diene rubber (PP/EPDM) blends are primarily reviewed. The morphology and rheology of these TPVs are also touched upon.

Fibrillin molecules aggregate to form an extendible beaded structure which is a major component of “Elastin Associated” microfibrils

1989 ◽  
Vol 47 ◽  
pp. 246-247
Author(s):  
Douglas R. Keene ◽  
B. Kerry Maddox ◽  
Marie B. Spurgin ◽  
Lynn Y. Sakai ◽  
Robert W. Glanville
Keyword(s):  
Molecular Sieve ◽  
Room Temperature ◽  
Culture Medium ◽  
Weight Fraction ◽  
Ammonium Bicarbonate ◽  
High Molecular Weight Fraction ◽  
Bicarbonate Buffer ◽  
Human Amnion ◽  
Gold Conjugate ◽  
Ammonium Bicarbonate Buffer

A mouse monoclonal antibody was used to identify beaded aggregates found in guanidine extracts of human amnion as assemblies of fibrillin molecules. These aggregates were also shown to be a major component of extracellular matrix microfibrils. We further demonstrated that the periodicity of these aggregates can be increased when subjected to mechanical stress.Human amnion was extracted with guanidine and the extracted material purified using ion exchange and molecular sieve chromatography. A high molecular weight fraction was precipitated by dialyzing against dilute acetic acid. Part of the precipitate was suspended in 0.2 M ammonium bicarbonate buffer and rotary shadowed. A second portion was resuspended in culture medium containing antibody which recognizes matrix microfibrils, diluted 1:5 in ammonium bicarbonate and reacted for 120 minutes at room temperature. Antibody labeled precipitate was washed by repeated pelleting and resuspension in buffer and then incubated in Janssen GAM 5 nm gold conjugate for 60 minutes at room temperature.

The Influence of Silicon Dopant and Processing on Thermoelectric Properties of B4C Ceramics

1998 ◽  
Vol 545 ◽  
Author(s):  
Ke-Feng Cai ◽  
Ce-Wen Nan ◽  
Xin-Min Min
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Figure Of Merit ◽  
Room Temperature ◽  
A Value ◽  
Si Doped

AbstractB4C ceramics doped with various content of Si (0 to 2.03 at%) are prepared via hot pressing. The composition and microstructure of the ceramics are characterized by means of XRD and EPMA. Their electrical conductivity and Seebeck coefficient of the samples are measured from room temperature up to 1500K. The electrical conductivity increases with temperature, and more rapidly after 1300K; the Seebeck coefficient of the ceramics also increases with temperature and rises to a value of about 320μVK−1. The value of the figure of merit of Si-doped B4C rises to about 4 × 10−4K−1 at 1500K.

scholarly journals Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shoufeng Lan ◽  
Xiaoze Liu ◽  
Siqi Wang ◽  
Hanyu Zhu ◽  
Yawen Liu ◽  
...  
Keyword(s):  
Time Reversal ◽  
Room Temperature ◽  
Photochemical Reactions ◽  
Full Width ◽  
Half Maximum ◽  
A Value ◽  
Device Applications ◽  
Spectral Splitting ◽  
Iron Garnet ◽  
Spontaneous Magnetic Moment

AbstractThe interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.

Doping and crystallization of amorphous SiGe films with an excimer (KrF) laser

1995 ◽  
Vol 10 (8) ◽  
pp. 1884-1888 ◽  
Author(s):  
S. Krishnan ◽  
M.I. Chaudhry ◽  
S.V. Babu
Keyword(s):  
Silicon Germanium ◽  
Room Temperature ◽  
Laser Pulses ◽  
Laser Exposure ◽  
Silicon Substrates ◽  
A Value ◽  
Crystal Film ◽  
Krf Laser ◽  
Amorphous Silicon Germanium

Amorphous silicon germanium (a-SiGe) films, deposited on silicon substrates at room temperature in a molecular beam epitaxy system, were transformed into a single-crystal film and doped with phosphorus by exposure to KrF laser pulses. Electron channeling patterns showed that laser exposure resulted in crystallization of the undoped a-SiGe films. The SiGe films were doped by laser irradiation, using a phosphorus spin-on-dopant. The sheet resistance of the doped films decreased with increasing numbers of pulses, reaching a value of about ∼ 5 × 104 ohms/□ after 15 pulses. I-V data from mesa-type n-SiGe/p-Si diode devices were used to determine the effect of laser processing on the quality of the SiGe films.

Thermooxidative Aging Studies on Silicone Rubber and Lifetime Prediction

2013 ◽  
Vol 777 ◽  
pp. 11-14
Author(s):  
You Shan Wang ◽  
Sha Sha Jiang ◽  
Yu Peng Liu
Keyword(s):  
Silicone Rubber ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Activation Energies ◽  
Lifetime Prediction ◽  
Arrhenius Behavior ◽  
Compression Set ◽  
Degradation Processes ◽  
Aging Studies ◽  
Significant Compression

Silicone rubber have been aged in air while under 25% compression at temperature up to 250°C. These studies examined the compression set of silicone rubber at accelerated (elevated) temperatures and were then used to make predictions about compression set at room temperature. The data obtained could be amenable to timetemperature superposition and Arrhenius treatment. The results suggest the presence of two degradation processes with activation energies of 71.6 kJ mol-1 (for temperatures above 165 °C) and 26.08 kJ mol-1 (for temperatures below 165 °C). Based on the extrapolation of the non-Arrhenius behavior, it was estimated that significant compression set loss would occur after around 67 years at 25 °C.

scholarly journals Preparation of Whey-Based Banana Beverage and its Quality Evaluation

2021 ◽  
Vol 5 (01) ◽  
pp. 60-66
Author(s):  
Kunjal Shrestha ◽  
Abhishek Dahal
Keyword(s):  
Sensory Analysis ◽  
Room Temperature ◽  
Storage Time ◽  
Value Added ◽  
Body Color ◽  
Overall Acceptability ◽  
A Value ◽  
Banana Juice ◽  
Nutritional Qualities ◽  
The One

A value-added functional beverage was formulated utilizing unprocessed whey with excellent nutritional qualities and bland flavors; along with banana juice and the required amount of sugar. Five different formulations were prepared with varying proportions of whey, banana juice, and sugar. Sensory analysis was carried out for all five formulations and based on statistical analysis the one which showed the highest value for body, color, flavor, taste, and overall acceptability was selected for further analysis (85% liquid whey and 15% banana juice). The shelf-life of the final product was observed for 30 days at room temperature (25±5°C) and refrigerated temperature (7±1ºC). A significant variation in body, color, flavor, taste, and overall acceptability were observed by varying the composition of whey and banana juice (p<0.05). The beverage was pasteurized at 82.5°C for 20 min and stored at normal (25±5°C) and refrigerated (7±1°C) for 30 days. The effects of storage time and temperature on physicochemical (TSS, pH, acidity) and microbial (TPC, yeast & mold count) properties were evaluated. Out of five formulations, the one selected via sensory analysis had TSS of 12.4°Bx, total solids 14.21%, 0.302% acidity, pH 5.72, 5.087% reducing sugar, 0.53% protein, 0.56% ash, 0.87% crude fiber, 184.43mg potassium (mg/100gm) and 0.912mg vitamin C in 100 ml. The prepared beverage was stored for 30 days under refrigerated and normal conditions, and changes in TSS, pH and acidity were observed: 12.413.3%, 5.72-5.214, 0.32-0.43%, and 12.4-13.8%, 5.72-4.64, 0.32-0.68% respectively. Overall analysis showed that the beverage prepared with 85% liquid whey and 15% banana juice could be stored for 30 days under refrigerated conditions without the addition of preservatives.

scholarly journals Inhibitive Effect of Costus afer Extracts on Mild Steel Corrosion in Acidic Medium

2016 ◽  
Vol 7 ◽  
pp. 60-67
Author(s):  
Lebe A. Nnanna ◽  
Wisdom O. John ◽  
Tochukwu E. Esihe ◽  
Kelechi C. Denkoro ◽  
Victor I. Okparaku ◽  
...  
Keyword(s):  
Mild Steel ◽  
Room Temperature ◽  
Inhibition Efficiency ◽  
Gravimetric Method ◽  
Steel Corrosion ◽  
Corrosion Process ◽  
Inhibition Effect ◽  
A Value ◽  
Mild Steel Corrosion ◽  
Costus Afer

Inhibition effect of Costusafer on mild steel in 0.5 M HCl was studied using gravimetric method at room temperature. It was found out that Costusafer inhibited the corrosion of mild steel in the acidic environment and that the efficiency of inhibition increased as the concentration of the inhibitor in the environment increased. The data was used to test different isotherms and it suited the Langmuir isotherm. A value of -15.995 kJmol-1 was gotten for the ∆Goads. This value showed that the extracts of Costusafer inhibited the corrosion process through physiosorption mechanism. The high value of inhibition efficiency of the extract as the concentration increased in rationalized in terms of the increase in herteroatoms, saponnins and tannins which are present in the extract.

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