Vulcanizing of Ebonite. Controlled Curing of Natural and Synthetic Rubber Ebonites of Large Cross-Section

1944 ◽  
Vol 17 (1) ◽  
pp. 192-193
Author(s):  
N. G. Quinn
Keyword(s):  
Low Temperature ◽  
Cross Section ◽  
Curing Temperature ◽  
Considerable Reduction ◽  
Curing Process ◽  
Curing Time ◽  
Large Cross Section ◽  
Synthetic Rubber ◽  
Curing Period ◽  
Natural And Synthetic

Abstract The vulcanizing of ebonite, particularly of large blocks or bars of substantial cross-section, has long been a source of production difficulty. The tendency of such vulcanizates to develop porosity or even more serious gassing has always necessitated a prolonged curing period at a comparatively low temperature. Improved compounding technique has greatly accelerated the curing process, but the period is still excessive and production is impaired. The proposed method of control enables a higher curing temperature to be used, with a consequent considerable reduction in curing time; it further makes possible the use of stocks which previously could not be satisfactorily cured at all above a certain thickness.

Effect of Storage and Temperature on Flexibility of Natural and Synthetic Rubbers

1948 ◽  
Vol 21 (4) ◽  
pp. 864-876
Author(s):  
John B. Gregory ◽  
Irving Pockel ◽  
John F. Stiff
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Strain Curve ◽  
Polymer Chains ◽  
Stress Strain Curve ◽  
Low Temperature Storage ◽  
Synthetic Rubber ◽  
Loading And Unloading ◽  
Temperature Storage ◽  
Natural And Synthetic

Abstract A new method for measuring the flexibility of rubber has been described. The method consists essentially in determining the stress-strain curve obtained by loading and unloading a loop formed from a one-inch by six-inch strip cut from a test slab. A coefficient of flexibility independent of the thickness of the sample and, in addition, information on per cent resilience were obtained. By the use of the method described, the behavior of various natural and synthetic rubber gas mask facepiece compounds was studied during one month to three months' exposure at various temperatures down to −20° F. Progressive stiffening probably due to crystallization was found for natural rubber, GR-I, and GR-M compounds at low temperatures. No tendency to crystallize was noted for the GR-S compound. Of the crystallizable polymers GR-I was the most resistant, and GR-M the least resistant to stiffening during low temperature storage. It is of course evident that different polymers have inherently different degrees of resistance to low temperatures. Disregarding these inherent differences the work reported indicates that the resistance of elastomer compounds to stiffening during prolonged low temperature storage is favored by the following: 1. Use of interpolymers made from monomer mixtures having a relatively large proportion of each component, thus obtaining mutual intereference with crystallization. 2. Use of a “tight” cure which probably so impedes the movement of the polymer chains as to make crystallization difficult.

Natural and Synthetic Rubber. II. Reduction of Isoprene by Na-Nh3

1929 ◽  
Vol 2 (3) ◽  
pp. 452-452
Author(s):  
Thomas Midgley ◽  
Albert L. Henne
Keyword(s):  
Molecular Weight ◽  
Double Bond ◽  
Low Temperature ◽  
High Molecular Weight ◽  
Liquid Ammonia ◽  
Volatile Hydrocarbon ◽  
Hydrogen Addition ◽  
Synthetic Rubber ◽  
Reaction Proceeds ◽  
Natural And Synthetic

Abstract The reduction of isoprene by sodium in liquid ammonia was attempted to determine: (1) whether reduction would take place in preference to polymerization and (2) the location of the added hydrogen. Isoprene was added to sodium dissolved in liquid ammonia and a 60% yield of 2-methyl-2-butene resulted. No other volatile hydrocarbon was found. High molecular weight hydrocarbons were formed but were not investigated. It is thus shown: (1) that the predominant reaction proceeds in accordance with the equation C5C8+2Na+2NH3=C5C10+2NaNH2 and (2) that hydrogen adds to isoprene in the 1,4-position, in agreement with Thiele's theory. The hydrogen addition is similar to the bromination of isoprene at low temperature. If properly conducted the latter reaction stops after 2 atoms of bromine have been added to 1 molecule of isoprene; the resulting compound, 1,4-dibromo-2-methyl-2-butene, is characterized b the inactivity of its double bond toward bromine. Similarly, 2-methyl-2-butene obtained by reduction of isoprene is not reduced to isopentane by an excess of Na—NH3 reagent.

Optimization of the Uncooked Oratosquilla Oratoria Curing Process via Response Surface Methodology

2014 ◽  
Vol 1073-1076 ◽  
pp. 1793-1797
Author(s):  
Qi Wei Mao ◽  
Jun Rui Wu ◽  
Xi Qing Yue
Keyword(s):  
Pathogenic Bacteria ◽  
Raw Materials ◽  
Curing Temperature ◽  
Curing Process ◽  
Curing Time ◽  
Optimal Process ◽  
Curing Conditions ◽  
Oratosquilla Oratoria ◽  
Sensory Score ◽  
Total Bacteria

Oratosquilla oratoria was the experimental raw materials in the paper. Design expert8.0.6 and Excel2007 was used to analyze the optimal process with the factors which were curing time, curing temperature, curing salt contention and the index which was the total bacteria. The pathogenic bacteria and sensory score under various curing conditions were determined simultaneously. After analyzing the significance of the various factors and interactions, the results showed the optimum curing conditions of oratosquilla oratoria were as follows: curing time 7.14h, curing temperature 14.34°C, curing salt contention 8.3%. Under this condition no pathogenic bacteria was detected and the sensory score was the highest.

New Photosensitive Dielectric Material for High-Density RDL with Ultra-Small Photo-Vias and High Reliability

2018 ◽  
Vol 2018 (1) ◽  
pp. 000466-000469 ◽  
Author(s):  
Daichi Okamoto ◽  
Yoko Shibasaki ◽  
Daisuke Shibata ◽  
Tadahiko Hanada
Keyword(s):  
Residual Stress ◽  
Low Temperature ◽  
Dielectric Material ◽  
High Reliability ◽  
Dielectric Materials ◽  
High Density ◽  
Curing Temperature ◽  
Temperature Cycle ◽  
Curing Process ◽  
Additive Process

Abstract This paper presents an advanced ultra-thin photosensitive dielectric Film (PDM) newly developed with high resolution, low CTE and low residual stress for next-generation high-density redistribution layer (RDL), 2.5D interposer, and high-density fan-out package applications. For high-density RDL, photosensitive dielectric materials need to have low CTE to achieve high package reliability. The CTE of the material is 30–35ppm/K. While maintaining the low CTE, we successfully demonstrated the minimum micro-via diameter of 3um in the 5um thickness. Curing temperature of the PDM is 180°C × 60 min. which is lower than most of the advanced dielectric materials which currently used in industry. Low-temperature curing process results in low stress. We have calculated residual stress in the cured PDM from a test result of warpage measurement on 4 inch wafer. As another benefit of the PDM material in curing process, the PDM can be cured in air oven. Most of advanced photo dielectric materials need to cure in N2 oven due to prevent an oxidation of the material. We have demonstrated copper traces of 2um lines and spaced on the PDM by using semi-additive process (SAP) with sputtered Ti/Cu seed layer. Thanks to the low CTE and low residual stress due to the low-temperature curing, it passed temperature cycle test (1,000 cycles) with daisy chain structure which has 400 vias in the structure. It can be concluded that the newly developed PDM is a promising dielectric material for highly reliable high-density redistribution layer (RDL) for 2.5D interposers and fan-out wafer level package applications.

Investigating the Effect of Vulcanization in Tread Rubber Applications

2013 ◽  
Vol 751 ◽  
pp. 1-7
Author(s):  
Jatinder Kumar ◽  
Rupinder Singh
Keyword(s):  
Manufacturing Industry ◽  
Curing Temperature ◽  
Curing Time ◽  
Synthetic Rubber ◽  
Potential Applications ◽  
Sulphur Vulcanization ◽  
Present Experimentation ◽  
Vulcanization Process ◽  
Tread Rubber ◽  
Model Strength

Retreading has many potential applications in tyre manufacturing industry. There is a critical need for optimization of vulcanization processes used in tread manufacturing. Not much work hitherto has been reported for optimization of efficient sulphur vulcanization process of the tread manufacturing. The present experimentation work highlights approach to macro-model strength, elongation and hardness during vulcanization of rubber. Relationship between strength, elongation, hardness and other parameter has been deduced by using Taguchi L9 orthogonal array (OA). Results indicate that the hardness, elongation and strength of tread rubber while vulcanization depends significantly on the natural: synthetic rubber ratio (NR: SR), curing time and curing temperature of the rubber.

Deep eutectic solvent for curing of phthalonitrile resin: Lower the curing temperature but improve the properties of thermosetting

2020 ◽  
pp. 095400832097215
Author(s):  
Yu Qi ◽  
Zhihuan Weng ◽  
Ce Song ◽  
Yue Hu ◽  
Xin Liu ◽  
...  
Keyword(s):  
High Performance ◽  
Oxidation Stability ◽  
Deep Eutectic Solvent ◽  
Curing Temperature ◽  
Molar Ratio ◽  
Curing Agent ◽  
Curing Process ◽  
Curing Time ◽  
Functional Pathway

Long curing duration and high curing temperature are commonly known to restrict the application of the phthalonitrile resin. In this study, a deep eutectic solvent (DES) containing ZnCl2 and urea has been developed to improve the curing process of the resorcinol-based phthalonitrile resin (DPPh) without sacrificing the useful properties of the resin. For the molar ratio of ZnCl2 and urea as 1:1 (ZnCl2-urea (1–1)), the initial curing temperature and apparent activation energy of the system were recorded as 179.5°C and 90.1 kJ/mol, respectively, indicating a reduction of 31.2% and 39.0% as compared to the pristine ZnCl2 system. More importantly, with curing time of 6 h and post-curing temperature of 300°C, the temperature at 5% weight loss as well as glass transition temperature of the resin with DES as the curing agent were 523.1°C and 370.2°C, respectively, demonstrating a significant improvement as compared to the resin cured with ZnCl2. In addition, the satisfactory long-term oxidation stability of the resin could also be obtained by employing the new curing agent. The findings from this study open a functional pathway for facile preparation of the high-performance curing agent for the phthalonitrile resin.

Air exchange dynamics in the system of large cross-section blind roadways

2020 ◽  
Vol 2 ◽  
pp. 46-57
Author(s):  
S.V. Maltsev ◽  
◽  
B.P. Kazakov ◽  
A.G. Isaevich ◽  
M.A. Semin ◽  
...  
Keyword(s):  
Cross Section ◽  
Large Cross Section ◽  
Air Exchange

scholarly journals Compressive Strength Gain Behavior and Prediction of Cement-Stabilized Macadam at Low Temperature Curing

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yongli Xu ◽  
Guang Yang ◽  
Hongyuan Zhao
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
Curing Temperature ◽  
Strength Development ◽  
Construction Process ◽  
Strength Gain ◽  
Estimation Model ◽  
Maturity Method ◽  
Temperature Ranges ◽  
Natural Temperature

For cement-based materials, the curing temperature determines the strength gain rate and the value of compressive strength. In this paper, the 5% cement-stabilized macadam mixture is used. Three indoor controlled temperature curing and one outdoor natural curing scenarios are designed and implemented to study the strength development scenario law of compressive strength, and they are standard temperature curing (20°C), constant low temperature curing (10°C), day interaction temperature curing (varying from 6°C to 16°C), and one outdoor natural temperature curing (in which the air temperature ranges from 4°C to 20°C). Finally, based on the maturity method, the maturity-strength estimation model is obtained by using and analyzing the data collected from the indoor tests. The model is proved with high accuracy based on the validated results obtained from the data of outdoor tests. This research provides technical support for the construction of cement-stabilized macadam in regions with low temperature, which is beneficial in the construction process and quality control.

scholarly journals Effect of Curing Agents on Electrical Properties of Low-Temperature Curing Conductive Coatings and Thermodynamic Analysis

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 656
Author(s):  
Junjie Shu ◽  
Yang Wang ◽  
Bei Guo ◽  
Weihua Qin ◽  
Lanxuan Liu ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Low Temperature ◽  
Surface Resistance ◽  
Advanced Manufacturing ◽  
Curing Time ◽  
Conductive Coatings ◽  
Exponential Factor ◽  
Design Expert ◽  
Surface Method ◽  
Curing Agents

Silver-based high-conductivity coatings are used in many advanced manufacturing equipment and components, and existing coatings require high-temperature curing. This paper studies the effects of different curing agents on the electrical properties of low-temperature curing (<100 °C) conductive coatings, and analyzes the effects of different curing temperatures and curing time on the surface resistance, square resistance and resistivity of conductive coatings. The response surface method in Design Expert was used to construct the model, and the curing thermodynamics of different curing agents were analyzed by DSC. It was found that curing agents with lower Tm and activation energy, higher pre-exponential factor and more flexible segments are beneficial to the preparation of highly conductive coatings.

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