Devulcanization of Guayule Rubber by Ultrasound

1999 ◽  
Vol 72 (5) ◽  
pp. 854-861 ◽  
Author(s):  
Eduardo A. Gonzalez-de los Santos ◽  
Florentino Soriano-Corral ◽  
Ma Josefina Lozano-Gonzalez ◽  
Rodrigo Cedillo-Garcia
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ultrasonic Irradiation ◽  
Crosslink Density ◽  
Gel Fraction

Abstract The present study describes the effect of ultrasonic irradiation on vulcanized guayule rubber using 1 to 3.5 parts per hundred of rubber (phr) of sulfur as the crosslink agent. The effect on crosslink density, gel fraction, torque and glass transition temperature was measured. After exposure to different powers of ultrasonic irradiation, the devulcanization effect was evident on the guayule rubber samples.

Looking at Rubber Adhesion

1979 ◽  
Vol 52 (1) ◽  
pp. 23-42 ◽  
Author(s):  
A. D. Roberts
Keyword(s):  
Surface Roughness ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Surface Energy ◽  
Crosslink Density ◽  
Central Theme ◽  
Rubber Compound ◽  
Rate Dependent ◽  
Peel Adhesion

Abstract Rubber has been employed in contact with a variety of surfaces for decades, yet the adhesional mechanisms involved are not fully understood. This article describes fundamental investigations carried out over the last decade. Emphasis is placed upon the use of optical techniques for looking directly at the contact area rubber makes with another surface. The interpretation is based upon a rate-dependent surface energy approach. In this way it is possible to predict the level of peel adhesion between surfaces, for example, when a ball rolls on smooth rubber. Other examples treated in the same way are the time for detachment of a ball from a smooth rubber track under gravity, its resilience when bounced on the track, and its friction when slid over the track. The influence of surface roughness, electrostatic forces, surface bloom, and humidity are considered, together with rubber compound variables such as glass transition temperature, crosslink density, and fillers. The central theme is that the adhesional mechanisms all physically depend upon the product of surface properties and bulk viscoelasticity of the solids in contact.

Enhancement of the crosslink density, glass transition temperature, and strength of epoxy resin by using functionalized graphene oxide co-curing agents

2016 ◽  
Vol 7 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Jin Won Yu ◽  
Jin Jung ◽  
Yong-Mun Choi ◽  
Jae Hun Choi ◽  
Jaesang Yu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Graphene Oxide ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Crosslink Density ◽  
Functionalized Graphene ◽  
Functionalized Graphene Oxide ◽  
Curing Agents

Epoxy nanocomposites are fabricated by using diamine-functionalized GO and exhibit high Tg, tensile strength, and crosslink density.

Effect of Crosslink Type on the Ultrasound Devulcanization of SBR Vulcanizates

1997 ◽  
Vol 70 (4) ◽  
pp. 641-649 ◽  
Author(s):  
V. Yu Levin ◽  
S. H. Kim ◽  
A. I. Isayev
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crosslink Density ◽  
Continuous Process ◽  
Ultrasound Irradiation ◽  
Processing Conditions ◽  
Power Ultrasound ◽  
High Power Ultrasound ◽  
Initial Fraction

Abstract Sulfur-cured non-reinforced SBR with different amounts of poly-, di- and monosulfidic crosslinks is devulcanized by high power ultrasound irradiation in a continuous process under various processing conditions. Total crosslink density, the proportion of polysulfidic crosslinks, gel fraction, and glass transition temperature are measured. The effect of the initial fraction of polysulfidic bonds on the devulcanization process is discussed.

Controlled degradation of epoxy networks: analysis of crosslink density and glass transition temperature changes in thermally reworkable thermosets

Polymer ◽  
2004 ◽  
Vol 45 (6) ◽  
pp. 1939-1950 ◽  
Author(s):  
Jir-Shyr Chen ◽  
Christopher K Ober ◽  
Mark D Poliks ◽  
Yuanming Zhang ◽  
Ulrich Wiesner ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crosslink Density ◽  
Temperature Changes ◽  
Epoxy Networks ◽  
Networks Analysis

A Study of the Effect of Maleic Anhydride on the Synthesis, Morphology, and Properties of Acrylonitrile Butadiene Styrene Plastic

2018 ◽  
Vol 45 (6) ◽  
pp. 251-256 ◽  
Author(s):  
O.M. Trifonova ◽  
Yu.A. Panova ◽  
I.G. Akhmetov
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Maleic Anhydride ◽  
Acrylonitrile Butadiene Styrene ◽  
Melt Flow Index ◽  
Flow Index ◽  
Melt Flow ◽  
Gel Fraction ◽  
Butadiene Styrene

The results of investigating the synthesis of ABS plastic in the presence of maleic anhydride are set out. It was shown that increase in the modifier content in the range 0.5–1.75 wt% leads to a reduction in the melt flow index and gel-fraction swelling index and to an increase in the glass transition temperature of the polymer.

Study of Thermal Aging of Nadimide Polymer: Physicochemical Characterization of the Properties of the Crosslinked IP960 System

1996 ◽  
Vol 8 (4) ◽  
pp. 579-598 ◽  
Author(s):  
J P Habas ◽  
J Peyrelasse ◽  
M F Grenier-Loustalot
Keyword(s):  
Weight Loss ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Treatment ◽  
Crosslink Density ◽  
Chemical Structure ◽  
Physicochemical Characterization ◽  
Minimal Period

In order to evaluate the thermostability of the IP960 polymer, we have characterized the physicochemical properties of samples exposed at 295 °C for periods up to 3000 h. According to the time of thermal treatment, various phenomena occur such as an increase in glass transition temperature and crosslink density. After a minimal period of 200 h at 295 °C, the weight loss of samples is representative of the degradation of crosslinked IP950. Using FTIR, we have analysed the changes in the chemical structure of the polymer. We propose a mechanism which could explain the degradation of the crosslinked compound.

Chemorheological Study of Vulcanized Rubbers under Mechanical Stress

1972 ◽  
Vol 45 (4) ◽  
pp. 1074-1081 ◽  
Author(s):  
T. Kusano ◽  
Y. Suzuki ◽  
K. Murakami
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mechanical Stress ◽  
Crosslink Density ◽  
Room Temperature ◽  
Mechanical Stimulus ◽  
Nitrogen Atmosphere

Abstract Below the glass transition temperature, the cleavage of molecular chains of extended vulcanized rubbers will occur. The crosslink density of vulcanized rubbers, which were placed at room temperature for about 4 h in a nitrogen atmosphere, increased about 17 per cent after extension of 200 per cent at −76° C. This may be due to the recombination of cleft chains, and this can be shown by the Maxwellian type of curves resulting from a plot of crosslink density as a function of forced strain. The decreasing proportion of crosslink density in the presence of radical acceptors in the rubbers and the increasing crosslink density in the absence of radical acceptors, because of recombination of cleft chains, was ascribed to the recombination of unstable chains produced by the added mechanical stimulus.

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