Mechanistic Investigations into the Adhesion between RFL-Treated Cords and Rubber. Part I: The Influence of Rubber Curatives

2007 ◽  
Vol 80 (4) ◽  
pp. 545-564 ◽  
Author(s):  
W. B. Wennekes ◽  
J. W. M. Noordermeer ◽  
R. N. Datta
Keyword(s):  
Adhesion Force ◽  
Resorcinol Formaldehyde ◽  
Scientific Investigations ◽  
Rubber Compounds ◽  
Brittle Layer ◽  
Cure Time ◽  
Rubber Part ◽  
Peel Adhesion ◽  
Peel Force

Abstract The adhesion between virgin textile cords and rubber is always weak, because of significant differences between fiber and rubber in modulus, elongation, polarity as well as reactivity. In order to improve the adhesion, it is customary to use adhesive systems, which act as bridges between elastomer and reinforcement. These are commonly based on Resorcinol/Formaldehyde/Latex (RFL) dips. For polyester and aramid fibers, two dip systems are applied. The first one is an epoxy pre-dip and the second dip is a RFL dip again. Although several mechanisms are proposed to explain the role of RFL, the majority of these explanations are based on assumptions rather than proper scientific investigations. In this paper an attempt is made to understand the role of the rubber vulcanization system on RFL-to-rubber bonding as judged by measuring the H-pullout force, Strap Peel Adhesion Force (SPAF) and the mechanical properties of the compounds. A positive correlation is found between the optimum cure time (t90) of the rubber compounds and the pullout and peel force. In literature this is commonly explained by the lack of curative migration from the rubber into the dip when t90 is low. In the present paper curative migration is monitored by scanning electron microscopy coupled to an energy dispersive X-ray spectrometer (SEM-EDX). A strong enrichment of curatives in the RFL dip near the interface is observed. A high accelerator loading results in a low t90 of the rubber compound as well as a more pronounced enrichment of curatives in the dip near the interface. Therefore the drop in adhesion does not occur because of lack of curative migration from rubber to the RFL layer, but more likely due to overcure of the latex in the dip, causing a brittle layer resulting in low pullout and peel strengths.

Mechanistic Investigations into the Adhesion between RFL-Treated Cords and Rubber. Part II: The Influence of the Vinyl-Pyridine Content of the RFL-Latex

2007 ◽  
Vol 80 (4) ◽  
pp. 565-579 ◽  
Author(s):  
W. B. Wennekes ◽  
R. N. Datta ◽  
J. W. M. Noordermeer
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Adhesive Systems ◽  
Resorcinol Formaldehyde ◽  
X Ray ◽  
Rubber Compounds ◽  
Vinyl Pyridine ◽  
Fundamental Understanding ◽  
Rubber Part ◽  
Scanning Electron

Abstract The adhesion between virgin textile cords and rubber is always weak, because of significant differences between fiber and rubber in modulus, elongation, polarity as well as reactivity. In order to improve the adhesion, it is common to use adhesive systems, which act as bridges between elastomer and reinforcement. These are commonly based on Resorcinol/Formaldehyde/Latex (RFL) dips. Despite the fact that this technique was invented in 1938 and no major improvements have been achieved since then, the mechanism by which the adhesion is obtained is still unclear. This paper contributes more fundamental understanding of RFL to rubber bonding. In previous work an enrichment of curatives at the RFL-rubber interface was observed by use of a Scanning Electron Microscope coupled to an Energy Dispersive X-ray spectrometer. In the present paper, the same method is used to determine the degree of enrichment for several RFL formulations, based on latices with varying vinyl-pyridine (VP) contents. The vinyl-pyridine content is varied by copolymerization of various VP terpolymers. Adhesion decreases with increasing vinyl-pyridine content for most rubber compounds. For aN NR compound with low accelerator content and a NR/SBR blend, an optimum vinyl-pyridine content of 10% is observed.

Effects of Rubber and Mould Temperatures on the Solid Tire Curing Process

2020 ◽  
Vol 856 ◽  
pp. 323-330
Author(s):  
Sitthichai Limrungruengrat ◽  
Arisara Chaikittiratana ◽  
Tonkid Chantrasmi ◽  
Sacharuck Pornpeerakeat ◽  
Utid Suripa
Keyword(s):  
Cure Kinetics ◽  
Mold Temperature ◽  
Process Efficiency ◽  
Manufacturing Cost ◽  
Curing Process ◽  
Finite Element Software ◽  
Rubber Compounds ◽  
Cure Time ◽  
Rubber Part ◽  
Rubber Component

Vulcanization or curing process is a very important process in producing useful rubber products. The quality, performance as well as manufacturing cost of a rubber product are largely affected by the curing process. The curing process takes place when heat is transferred to the rubber compounds inside a heated mould. Curing of a thick article, such as a solid tire, often occurs under transient non-isothermal conditions. The temperature distribution in the rubber significantly affects the cure level distribution throughout the part, especially in a large rubber component. Therefore the ability to predict the distribution of cure level in a rubber part during curing is of great importance for improving the process efficiency and the quality of the final product. In this work, simulations of the curing process of a solid tire, consisting of three layers of different rubber compounds, were performed and the cure level distribution results were evaluated. The simulations are carried out using the commercial finite element software ABAQUS with the cure kinetics model for rubber implemented through the user subroutine UMATHT. The effects of the mold temperature and initial temperature of the solid tire on the cure level distribution and cure time were investigated.

The Small Mammal Project: Engaging Students as Scientists

2017 ◽  
Vol 79 (3) ◽  
pp. 200-206
Author(s):  
Erika V. Iyengar ◽  
Paul T. Meier ◽  
Rachel E. Hamelers
Keyword(s):  
College Courses ◽  
Scientific Process ◽  
Scientific Creativity ◽  
Scientific Investigations ◽  
Hands On ◽  
Upper Level ◽  
Multiple Species ◽  
Dissemination Of Results ◽  
Scientific Questions

This article describes a sustained, student-driven, inquiry-based set of activities meant to illuminate the scientific process from the initial scientific questions to oral dissemination of results. It is appropriate for science majors and nonmajors, advanced high school through upper-level college courses. Involving students in hands-on, self-driven investigations will allow them to see the challenges of quantitative scientific investigations, and the role of scientific creativity in experimental design and interpretation. This project allows a large group of students to engage in the type of research project often only available to students working one-on-one with instructors or in research labs. This activity requires skeletons of multiple species of small mammals, but there are many ways to alter the project to suit available resources. We expect that students involved in hands-on, self-directed scientific investigations early in their academic careers are less likely to view science as a mere accumulation of facts and more likely to be empowered to participate later in more sustained scientific investigations.

Calophyllum Inophyllum Oil as Plasticizer in Natural Rubber Compounds

2009 ◽  
Vol 25 (2) ◽  
pp. 113-128 ◽  
Author(s):  
P. Raju ◽  
V. Nandanan ◽  
Sunil K.N. Kutty
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Thermal Studies ◽  
Calophyllum Inophyllum ◽  
Compression Set ◽  
Peak Rate ◽  
Rubber Compounds ◽  
Cure Time ◽  
Calophyllum Inophyllum Oil ◽  
Control Compound

Mechanical properties and the thermal degradation characteristics of natural rubber compounds with calophyllum inophyllum oil were compared to that of the control compound containing naphthenic oil. The compounds containing calophyllum inophyllum oil showed improved tensile strength, tear strength, modulus, compression set, abrasion resistance and resilience. Cure time was higher than the naphthenic oil mixes. Thermal studies showed an increase of 8 °C in the temperature of initiation of degradation and an increase of 6 °C in temperature at which the peak rate of degradation occurred. The peak rate of degradation was comparable to the control mix containing naphthenic oil.

Prevulcanization Inhibitor the Chemistry of Scorch Delay

1970 ◽  
Vol 43 (5) ◽  
pp. 1188-1193 ◽  
Author(s):  
R. I. Leib ◽  
A. B. Sullivan ◽  
C. D. Trivette
Keyword(s):  
Delay Period ◽  
Crosslinking Process ◽  
Time Period ◽  
Rubber Compounds ◽  
Speed Up ◽  
Autocatalytic Process ◽  
Vulcanization Process

Abstract Sulfenamide accelerators serve to perform two functions. They provide the necessary time period required to mix, process and shape rubber compounds. This portion of the overall vulcanization process is usually referred to as scorch delay. In addition, sulfenamides function as accelerators, in that once the crosslinking process has begun, they speed up this reaction. The delay period occurs because the sulfenamide must be converted to polythiobenzothiazoles, the precursors to crosslinking, before crosslinking can take place. The overall reaction of sulfenamide with sulfur is an autocatalytic process with MBT the autocatalyst. The role of PVI in this scheme is to remove MBT from this autocatalytic sequence of reactions, thus delaying those reactions which preceed crosslink formation.

Predicting optimum cure time of rubber compounds by means of ANFIS

2012 ◽  
Vol 35 ◽  
pp. 833-838 ◽  
Author(s):  
Bağdagül Karaağaç ◽  
Melih İnal ◽  
Veli Deniz
Keyword(s):  
Rubber Compounds ◽  
Cure Time

The Effect of Excess Silane-69 Used for Surface Modification on Cure Characteristic and Mechanical Properties of Precipitated Silica Filled Natural Rubber (PSi/NR)

2009 ◽  
Vol 79-82 ◽  
pp. 2171-2174 ◽  
Author(s):  
Chanchai Thongpin ◽  
C. Sangnil ◽  
P. Suerkong ◽  
A. Pongpilaiprertti ◽  
Narongrit Sombatsompop
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Crosslinking Density ◽  
High Concentration ◽  
Precipitated Silica ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Cure Time ◽  
Cure Characteristic ◽  
Characterization Test

This research is concentrated on the effect of concentration of silane-69 used for surface modification on precipitated silica (PSi), on cure characteristic and mechanical properties of PSi filled NR. The PSi content in this study was fixed at 20 phr in order to reveal the effect of silane used to modify PSi, on NR compound and vulcanizate. Moving Die Rheometer (MDR) was used to characterize cure characteristic of rubber compounds. Generally, scorch and cure time of NR would increase with the addition of PSi due to the absorption of accelerator on its surface whereas the addition of Si-69 modified PSi would reduce both scorch and cure time. It was found in this research that the excess amount of Si-69 used increased scorch and cure time of rubber compounds. This was thought to be that the excess of Si-69 led to the formation of polysiloxane clusters which could absorb accelerator in rubber compound and resulted in a prolonged scorch and cure time. In term of vulcanized rubber, it was found that maximum torque increased with the concentration of Si-69 up to 6 %. The polysiloxane formed during the cure characterization test was responsible for the slightly decreased torque after 6% of Si-69 treatment. Nonetheless, even with high concentration of Si-69 used, torque was still higher than that of untreated PSi filled NR. This is widely understood that sulfur atoms in Si-69 molecule are able to participate in the bonding between rubber and silane molecules resulted in the enhancement of crosslink density of the vulcanizate rubber. The increased of modulus at 200 % elongation, tensile strength under tension, with the silane concentration, was evidence of the crosslink enhancement. Tear strength and hardness of the vulcanizates exhibiting the increment, with the silane used, also clearly confirmed the bonding between Si-69 and rubber molecules. It was elucidated from the research that excess of Si-69 would lead to polysiloxane formation, cluster form of silane and crosslinking density. Scanning Electron Microscope (SEM) micrographs and swelling test are also presented to confirm the phenomena.

The Effect of Second Filler on Cure Characteristic and Mechanical Properties of Si-69 Treated Precipitate Silica/NR Composite

2009 ◽  
Vol 79-82 ◽  
pp. 2183-2186 ◽  
Author(s):  
Chanchai Thongpin ◽  
C. Sripetdee ◽  
N. Papaka ◽  
N. Pongsathornviwa ◽  
Narongrit Sombatsompop
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fly Ash ◽  
Rubber Compound ◽  
Maximum Torque ◽  
Elongation At Break ◽  
Rubber Vulcanizate ◽  
Rubber Compounds ◽  
Cure Time ◽  
Cure Characteristic

Silica has been widely used as non-black reinforcing filler, however, the filler-filler interaction has been an important issue. Cure characteristic and mechanical properties of the rubber compound and rubber vulcanizate were affected both by filler-rubber interaction and filler-filler interaction. There have been, presently, a number of natural fillers which are also used as fillers for the rubber, i.e. fly ash, sawdust and zeolite. This work therefore will study the effect of second filler added into the 13% Si-69 treated precipitate silica (PSi) filled natural rubber compounds. It was revealed that the scorch and cure time of the rubber compound increased with the content of treated PSi. This was the effect of excess of the silane treated onto PSi which would agglomerate and form the cluster of polysiloxane and would then be able to absorb vulcanizing accelerator resulting in extending the scorch and cure time of the rubber compounds. However, this effect was over ruled with the reinforcing effect as could be seen by the increasing, with the contents of PSi, of maximum torque and mechanical properties of the vulcanizates. The NR compounded with treated PSi content of 20 phr selected to study the effect of excess silane on the cure characteristic of hybrid fillers NR composite. The addition of sawdust led to longer scorch time and cure time but not much change of the maximum torque. As expected, the modulus of the rubber vulcanizate increased with the sawdust content whereas the tensile strength and elongation at break decreased with the sawdust content. The incorporation of zeolite could accelerate the cure reaction therefore both scorch time and cure time decreased. The maximum torque also increased with the content of zeolite. Both modulus and tensile strength increased with the content of the zeolite whereas elongation at break tended to be unchanged. In the case of using fly ash as the second filler, the cure time tended to be unchanged. However, the maximum torque tended to be increased with the content of fly ash. It was found that the modulus, tensile strength increased but elongation at break decreased. Interestingly, the excess of Si-69 used effect pronouncedly for the addition of zeolite and fly ash cases as the excess silane could promote the interaction between fillers surface and rubber molecule accept for sawdust

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