A Study of the Increase in Tensile Strength of Vulcanized Rubber when it Begins to Age

1949 ◽  
Vol 22 (4) ◽  
pp. 1028-1035
Author(s):  
Robert Judeinstein
Keyword(s):  
Tensile Strength ◽  
Network Structure ◽  
The State ◽  
Maximum Tensile Strength ◽  
Vulcanized Rubber

Abstract In conclusion, the present study confirms the phenomenon of an increase in tensile strength at the beginning of aging. The magnitude of this increase depends on the nature of the acceleration and the state of cure; the tensile strength of an undercured sample increases much more than that of a sample vulcanized to its optimum state of cure, and the maximum tensile strength reached by the former is definitely higher than the maximum tensile strength reached by the latter. The phenomenon is therefore not simply postvulcanization. This increase in tensile strength takes place in the presence of oxygen and also in a vacuum as high as 10−3 mm. In the latter case, measurements of the T-50 value and combined sulfur give indications of an increase in network structure for a given percentage of combined sulfur. Oxygen is a contributing factor in increasing the network structure, but, in its presence, combination of sulfur is not so great and the maximum tensile strength attained is lower.

Preliminary Study on Curing of Thick Rubber Article

2015 ◽  
Vol 1134 ◽  
pp. 23-27
Author(s):  
Siti Zulaikha Ibrahim ◽  
Che Mohd Som Said ◽  
Mohamad Asri Ahmad ◽  
Azemi Samsuri
Keyword(s):  
Tensile Strength ◽  
Temperature Region ◽  
The State ◽  
Curing Temperature ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Cure Time ◽  
Zinc Diethyldithiocarbamate ◽  
Preliminary Study ◽  
Rubber Article

In this study, several batches of natural rubber (SMR L) were compounded with three different types of accelerators, which were N-cyclohexylbenzothiazole-2-sulphenamide (CBS), diphenylguanidine (DPG) and zinc diethyldithiocarbamate (ZDEC). ZDEC is known as an ultrafast accelerator. The rubber compounds were cured at 140°C, 130°C, 120°C, 110°C and 100°C in accordance with the temperature gradients observed within the thick rubber block. The main aim of this study is to cure the rubber at each temperature region to the same cure time as that of the outermost region (20 minutes at 140°C). The amount of sulfur and accelerator were adjusted accordingly at each curing temperature to match the state of cure at 140°C. The state of cure of of the vulcanized rubbers were measured using hardness and tensile strength. The same state of cure is achieved if the hardness and tensile strength value are within ±2 IRHD and ±3 MPa, respectively with that of the control vulcanized rubber (hardness and tensile strength cured at 140°C). The results shows that the hardness and tensile strength of the vulcanized rubber at each temperature region are within the expected margins. The results clearly indicated that the type and amount of accelerators, and the amount of sulfur were correctly chosen at each temperature.

scholarly journals II. The elastic limits of iron and steel under cyclical variations of stress

1911 ◽  
Vol 210 (459-470) ◽  
pp. 35-55 ◽  
Keyword(s):  
Tensile Strength ◽  
Yield Stress ◽  
Simple Relation ◽  
Iron And Steel ◽  
Maximum Tensile Strength

Introduction . Since Wöhler’s original experiments on the fracture of iron and steel by repetition of stress, similar experiments have been made by independent observers, and all agree in showing that neither the maximum tensile strength nor the yield stress hears any simple relation to the range of stress which may be safely repeated. The only theory of fatigue, i . e . of failure due to repetition of stress, which has received serious attention was put forward by Bauschinger. According to this theory, specimens subjected to repetitions of stress begin to be fatigued when the stresses applied in each cycle are so great that the extension of the specimen is not wholly elastic.

scholarly journals The Optimum Process Parameter of Dissimilar Metal AA6061 – AISI304 Continuous Drive Friction Welding

2020 ◽  
Vol 55 (2) ◽  
Author(s):  
Totok Suwanda ◽  
Rudy Soenoko ◽  
Yudy Surya Irawan ◽  
Moch. Agus Choiron
Keyword(s):  
Tensile Strength ◽  
Response Surface ◽  
Process Parameters ◽  
Friction Welding ◽  
Welding Parameters ◽  
Optimum Process ◽  
Dissimilar Metals ◽  
Maximum Tensile Strength ◽  
Friction Pressure ◽  
Welding Processes

This article explains the use of the response surface method to produce the optimum tensile strength for the joining of dissimilar metals with the continuous drive friction welding method. The joining of dissimilar metals is one of the biggest challenges in providing industrial applications. Continuous drive friction welding has been extensively used as one of the important solid-state welding processes. In this study, the optimization of the friction welding process parameters is established to achieve the maximum tensile strength in AA6061 and AISI304 dissimilar joints via the response surface methodology. The effect of continuous drive friction welding parameters, which are friction pressure, friction time, upset pressure, and upset time, are investigated using response surface analysis. The design matrix factors are set as 27 experiments based on Box-Behnken. The 3D surface and the contour is plotted for this model to accomplish the tensile strength optimization. The optimization model of the tensile strength was verified by conducting experiments on the optimum values of the parameters based on the experimental data results. It can be denoted that the optimum process parameters settings were friction pressure = 25 MPa, friction time = 6 seconds, upset pressure = 140 MPa, and upset time = 8 seconds, which would result in a maximum tensile strength of 228.57 MPa.

scholarly journals Manufacturing Technique of Heat-Insulating and Flame-Retardant Three-Dimensional Composite Base Fabrics

2013 ◽  
Vol 8 (1) ◽  
pp. 155892501300800
Author(s):  
Jia-Horng Lin ◽  
Chen-Hung Huang ◽  
Ching-Wen Lin ◽  
Ching Wen Lou
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Melting Point ◽  
Flame Retardant ◽  
Three Dimensional ◽  
Weight Ratio ◽  
Air Permeability ◽  
Maximum Tensile Strength ◽  
Manufacturing Technique ◽  
Pu Foam

In this research, we create a PET/TPU/PU composite base fabric from a PET nonwoven base fabric, a TPU honeycomb grid, and a PU foam plank. First, the PET base fabric is made from 7D three-dimensional-hollow-crimp fiber (7D PET) and low-melting-point (low-Tm) fibers with weight ratio and number of lamination layers as the parameters. The hardness and rebound resilience rate of the PET nonwoven base fabric are 71% and 63.5%, respectively. The PET nonwoven base fabric's optimum air permeability is 240 cm3/s/cm2. The maximum tensile strength of the PET nonwoven base fabric with 9 layers of lamination is 39.8 kg/cm2, and when the weight ratio is either 4:6 or 3:7, changes to 40 kg/cm2. The PET/TPU/PU composite base fabric has a LOI of 33 when the number of lamination layers is 10, or when the low-Tm fiber content is 50%; the composite base fabric's average optimum thermal conductivity is 0.914 W/mK.

Mechanochemical Devulcanization of Vulcanized Gum Natural Rubber

2005 ◽  
Vol 21 (3) ◽  
pp. 183-199
Author(s):  
G.K. Jana ◽  
C.K. Das
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Three Dimensional ◽  
Elongation At Break ◽  
Tear Strength ◽  
Vulcanized Rubber ◽  
Dimensional Network ◽  
Polymeric Chains ◽  
Cure Time

De-vulcanization of vulcanized elastomers represents a great challenge because of their three-dimensional network structure. Sulfur-cured gum natural rubbers containing three different sulfur/accelerator ratios were de-vulcanized by thio-acids. The process was carried out at 90 °C for 10 minutes in an open two-roll cracker-cum-mixing mill. Two concentrations of de-vulcanizing agent were tried in order to study the cleavage of the sulfidic bonds. The mechanical properties of the re-vulcanized rubber (like tensile strength, modulus, tear strength and elongation at break) were improved with increasing concentrations of de-vulcanizing agent, because the crosslink density increased. A decrease in scorch time and in optimum cure time and an increase in the state of cure were observed when vulcanized rubber was treated with high amounts of de-vulcanizing agent. The temperature of onset of degradation was also increased with increasing concentration of thio-acid. DMA analysis revealed that the storage modulus increased on re-vulcanization. From IR spectroscopy it was observed that oxidation of the main polymeric chains did not occur at the time of high temperature milling. Over 80% retention of the original mechanical properties (like tensile strength, modulus, tear strength and elongation at break) of the vulcanized natural rubber was achieved by this mechanochemical process.

Design-of-experiments application in the friction stir welding of aluminium alloy AA 8011-h14 for structural application

2019 ◽  
Vol 16 (3) ◽  
pp. 606-622
Author(s):  
Navneet Khanna ◽  
Mahesh Bharati ◽  
Prachi Sharma ◽  
Vishvesh J. Badheka
Keyword(s):  
Tensile Strength ◽  
Aluminium Alloy ◽  
Tensile Testing ◽  
Visual Inspection ◽  
Welding Parameters ◽  
Nugget Zone ◽  
Content Type ◽  
Taguchi Analysis ◽  
Friction Stir ◽  
Maximum Tensile Strength

Purpose The demand for aluminium alloys has been increasing in almost all the fields. In this study, the friction stir welding (FSW) of similar aluminium alloy AA 8011-h14 has been presented using three levels of tool rotational speed (n), tool tilt angle (ϴ) and tool feed (f). The purpose of this paper is to study the effect of welding parameters on various properties and time-temperature plots. Design/methodology/approach FSW was carried out using the L-9 orthogonal array of welding parameters generated using the Taguchi approach. Visual inspection and radiography testing were conducted to detect the surface and volume defects, respectively. Taguchi analysis was carried out to get optimised welding parameters for tensile testing. The microstructural analysis was carried out for the specimen possessing maximum tensile strength and the obtained grain structures were compared with the microstructure results of the base material. The peak process temperatures were noted and time-temperature plots were analysed for the varying parameters. The maximum value of hardness was recorded and analysed. Findings Visual inspection and radiography testing confirmed defect-free joints. The maximum tensile strength achieved was 84.44 MPa with 64.95 per cent efficiency. The optimised parameters obtained using Taguchi analysis for tensile testing were 1,500 rpm, 1° and 50 mm/min. Microstructure analysis for the specimen possessing maximum tensile strength revealed fine and equiaxed grains in the nugget zone. Time-temperature plots suggested the maximum temperature of 389 °C on the advancing side. A maximum hardness value of 36.4 HV was obtained in the nugget zone. Originality/value As per the knowledge of the authors, this study is the first attempt for the detailed experimental analysis on the FSW of this particular aluminium alloy AA 8011-h14.

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