Nonisothermal Vulcanization of Rubber Compounds

1988 ◽  
Vol 61 (2) ◽  
pp. 340-361 ◽  
Author(s):  
A. I. Isayev ◽  
J. S. Deng
Keyword(s):  
Induction Time ◽  
The State ◽  
Model Parameters ◽  
Scanning Calorimetry ◽  
One Dimensional ◽  
Dsc Measurements ◽  
Rubber Compounds ◽  
Modulus Measurement ◽  
Heated Plates ◽  
Made In

Abstract In the present paper, progress has been made in developing a model for nonisothermal vulcanization of rubber compounds. The model is presently based on differential scanning calorimetry (DSC) measurements of heat evolved during vulcanization. The model parameters are determined from several isothermal DSC scans including measurements of induction time and rate of vulcanization. This model has conveniently been employed for a calculation of the temperature distribution during vulcanization of a rubber slab based on a one-dimensional heat-conduction equation with a heat-generation term. The simulation allowed us to predict the dynamics of the development of the state of cure distribution in the rubber slabs. Predicted results from the vulcanization model have been verified with experimental data on induction time and rate of vulcanization from nonisothermal DSC scans and with measurements of the state of cure distribution in rubber slabs cured under different vulcanization conditions between two heated plates. Although this model is based on DSC data, the approach developed can easily be extended to similar curing data obtained by means of the modulus measurement technique.

Using Ultrathin-Film, Modulated Composites to Control the Reaction Mechanism of Ternary Compound Formation

1991 ◽  
Vol 238 ◽  
Author(s):  
Loreli Fister ◽  
David C. Johnson
Keyword(s):  
Ternary Compound ◽  
Reaction Pathway ◽  
Experimental Parameter ◽  
Ultrathin Film ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Compound Formation ◽  
One Dimensional ◽  
X Ray ◽  
Made In

ABSTRACTA predictable, controllable approach to the synthesis of ternary compounds through known intermediates is presented. Thin and ultrathin film superlattices were made in the Mo-Se, Cu-Se and Mo-Cu systems. Differential scanning calorimetry, low- and high-angle x-ray diffraction were used to assess the interdiffusion and nucleation reactions between elemental layers in these one-dimensional crystals. The experimental parameter modulation distance was used to influence the interfacial reactions. The results from each binary system were then used to predict the reaction pathway in the synthesis of a ternary compound, Cu2Mo6Se8. Superlattices with two different lengthscales were investigated. In the first, only one intermediate, MoSe2 which typically crystallizes at ∼200'C, is observed prior to the crystallization of Cu2Mo6Se8. In the second, no crystalline intermediates are observed below 6000 C.

Injection Molding of Rubber Compounds: Experimentation and Simulation

1991 ◽  
Vol 64 (2) ◽  
pp. 296-324 ◽  
Author(s):  
J. S. Deng ◽  
A. I. Isayev
Keyword(s):  
Experimental Data ◽  
Injection Molding ◽  
Induction Time ◽  
Flow Simulation ◽  
Injection Molding Process ◽  
Model Parameters ◽  
Large Sample Size ◽  
Molding Process ◽  
Rubber Compounds ◽  
Pressure Development

Abstract Results of experimental and theoretical studies of injection molding of rubber compounds have been reported. Characterizations on the rheological properties and the vulcanization kinetics of rubber compounds were carried out by means of MPT and DSC, respectively. The models were employed to fit these experimental data. An attempt has been made in extending the proposed empirical kinetic model based on DSC data to similar curing data obtained by means of the MDR technique. The heat-transfer effect due to the large sample size used in MDR measurements has been found to have a small effect on the kinetic data. Due to the different principle of state-of-cure measurements in MDR and DSC, the model parameters of curing kinetics have been found to be different in these measurements. A two-dimensional flow simulation of generalized Newtonian fluids based on both finite-difference and finite-element methods has been performed. The pressure development at various positions along the flow path during the filling stage of the molds was obtained experimentally for various injection speeds. The predicted results on pressure development during cavity filling showed qualitative agreement with the experimental data. Possible reasons for the observed discrepancy in pressure traces are: neglect of local extra pressure losses (in the juncture sections), compressibility of rubber compounds, leakage (back-flow) of material during injection, and voids formation in the injection chamber. The study on the vulcanization behavior of rubber compounds during injection molding process has also been done. The proposed empirical kinetic and induction time models were able to satisfactorily predict the cure levels of molded rubber products. At the same time, the results predicted by employing nth order kinetics were found to be unsatisfactory. The contribution of nonisothermal induction time in calculating cure levels of the molded rubber products was found to be significant. The mechanical properties and anisotropy have been investigated for two rubber compounds. It is suggested that there exists a mold temperature at which the properties and cycle times are optimal, and the filler type shows a significant effect on the tensile modulus. The rubber moldings were found to be highly anisotropic in mechanical behaviors. The anisotropy could be reduced significantly at high injection speed due to the faster stress-relaxation process.

scholarly journals Phase Transitions of N-(4-methoxybenzylidene)-4-butylaniline (MBBA) Confined within Mesoporous Silica

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 792
Author(s):  
Takehisa Yoshimi ◽  
Ayumi Shima ◽  
Shoko Hagiwara-Norifusa ◽  
Takayuki Sugimoto ◽  
Atsushi Nagoe ◽  
...  
Keyword(s):  
Phase Transition ◽  
Nematic Phase ◽  
Three Dimensional ◽  
Porous Silica ◽  
Temperature Shift ◽  
Thermal Anomaly ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
One Dimensional ◽  
Dsc Measurements

We have used differential scanning calorimetry (DSC) to investigate the phase transition of a liquid crystal, N-(4-methoxybenzylidene)-4-butylaniline (MBBA), confined within porous silica materials with one- and three-dimensional pore architectures. Each phase-transition temperature of the confined MBBA linearly decreased with the inverse pore size compared with that of bulk MBBA. However, the degree of temperature shift varied owing to differences in the pore architectures. In addition, when MBBA was confined within one-dimensional pores, the thermal anomaly associated with the phase transition from the nematic phase to the isotropic liquid phase was not observed in the DSC measurements.

Chasing Angels: The Sweet Wine Angelica

2008 ◽  
Vol 8 (3) ◽  
pp. 74-78
Author(s):  
hank shaw
Keyword(s):  
The State ◽  
The Real ◽  
Mission Period ◽  
History Of ◽  
Uncertain Future ◽  
Sweet Wine ◽  
Made In

Portugal has port, Spain has sherry, Sicily has Marsala –– and California has angelica. Angelica is California's original wine: The intensely sweet, fortified dessert cordial has been made in the state for more than two centuries –– primarily made from Mission grapes, first brought to California by the Spanish friars. Angelica was once drunk in vast quantities, but now fewer than a dozen vintners make angelica today. These holdouts from an earlier age are each following a personal quest for the real. For unlike port and sherry, which have strict rules about their production, angelica never gelled into something so distinct that connoisseurs can say, ““This is angelica. This is not.”” This piece looks at the history of the drink, its foggy origins in the Mission period and on through angelica's heyday and down to its degeneration into a staple of the back-alley wino set. Several current vintners are profiled, and they suggest an uncertain future for this cordial.

BERLAKU DAN KEABSAHAN PERJANJIAN INTERNASIONAL DALAM PANDANGAN HUKUM INTERNASIONAL

2019 ◽  
Vol 1 (1) ◽  
pp. 95-103
Author(s):  
Komang Sukaniasa
Keyword(s):  
International Law ◽  
International Agreements ◽  
The State ◽  
International Agreement ◽  
International Treaties ◽  
International Treaty ◽  
Binding Force ◽  
International Rights ◽  
Legal Consequences ◽  
Made In

International agreements are agreements between international subjects that give rise to binding obligations in international rights, which can be bilateral or multilateral. Based on these opinions, an understanding can be taken that international treaties are agreements or agreements entered into by two or more countries as subjects of international law that aim to cause certain legal consequences. International agreements, whether ratified or through approval or acceptance or accession, or other methods that are permitted, have the same binding force as ratified international treaties established in the Ratification Law of International Treaties. Once again, it is equally valid and binding on the state. Therefore, the authors consider that the position of international treaties are not made in the form of the Ratification Act of the International Agreement but are binding and apply to Indonesia. Then Damos Dumoli Agusman argues that ratification originates from the conception of international treaty law which is interpreted as an act of confirmation from a country of the legal acts of its envoys or representatives who have signed an agreement as a sign of agreement to be bound by the agreement.

Multidimensional analysis of the state of Russian studies on the education issues over 1993–2016

2018 ◽  
pp. 50-62
Author(s):  
Дмитрий Рубвальтер ◽  
Dmitry Rubvalter ◽  
Александр Либкинд ◽  
Alexander Libkind ◽  
Валентина Маркусова ◽  
...  
Keyword(s):  
Web Of Science ◽  
The State ◽  
Multidimensional Analysis ◽  
Russian Regions ◽  
Global Flow ◽  
Educational Issues ◽  
Foreign Countries ◽  
High Level ◽  
The Web ◽  
Made In

A multidimensional analysis of the state of Russian studies on the education issues over 1993–2016 was carried out based on the materials of the data contained in the Web of Science (SSCI, A & HCI and SCI-E databases). There were determined the dynamics and trends of a number of relevant indicators, such as the number of Russian publications by year, the share of these publications in the global flow of publications on education issues, the dynamics of the share of publications made in co-authorship with foreign colleagues, etc. A number of distributions of Russian publications on educational issues was compiled and analyzed: by journals, by Russian regions and cities, by organizations and authors of the publications. It was found that most of these distributions were characterized by a high level of non-uniformity. A list of journals (125 titles) in which Russian works on education issues had been published was compiled. Russian organizations (308) and domestic researchers (about two thousand) engaged in studying the issues of education were identified. It was discovered that more than 200 organizations and about 400 academicians from 60 foreign countries had participated in Russian studies on the education issues.

scholarly journals Two-Stage Water Jet Landing Point Prediction Model for Intelligent Water Shooting Robot

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2704
Author(s):  
Yunhan Lin ◽  
Wenlong Ji ◽  
Haowei He ◽  
Yaojie Chen
Keyword(s):  
Pitch Angle ◽  
Back Propagation ◽  
Water Jet ◽  
The State ◽  
Model Parameters ◽  
Propagation Time ◽  
Back Propagation Algorithm ◽  
Angle Error ◽  
Landing Point ◽  
Propagation Algorithm

In this paper, an intelligent water shooting robot system for situations of carrier shake and target movement is designed, which uses a 2 DOF (degree of freedom) robot as an actuator, a photoelectric camera to detect and track the desired target, and a gyroscope to keep the robot’s body stable when it is mounted on the motion carriers. Particularly, for the accurate shooting of the designed system, an online tuning model of the water jet landing point based on the back-propagation algorithm was proposed. The model has two stages. In the first stage, the polyfit function of Matlab is used to fit a model that satisfies the law of jet motion in ideal conditions without interference. In the second stage, the model uses the back-propagation algorithm to update the parameters online according to the visual feedback of the landing point position. The model established by this method can dynamically eliminate the interference of external factors and realize precise on-target shooting. The simulation results show that the model can dynamically adjust the parameters according to the state relationship between the landing point and the desired target, which keeps the predicted pitch angle error within 0.1°. In the test on the actual platform, when the landing point is 0.5 m away from the position of the desired target, the model only needs 0.3 s to adjust the water jet to hit the target. Compared to the state-of-the-art method, GA-BP (genetic algorithm-back-propagation), the proposed method’s predicted pitch angle error is within 0.1 degree with 1/4 model parameters, while costing 1/7 forward propagation time and 1/200 back-propagation calculation time.

scholarly journals Polypropylene/Lignin/POSS Nanocomposites: Thermal and Wettability Properties, Application in Water Remediation

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3950
Author(s):  
Abeer Alassod ◽  
Syed Rashedul Islam ◽  
Mina Shahriari Khalaji ◽  
Rogers Tusiime ◽  
Wanzhen Huang ◽  
...  
Keyword(s):  
Organic Liquid ◽  
Contact Angles ◽  
Water Remediation ◽  
Scanning Calorimetry ◽  
Water Contact ◽  
Thermally Induced ◽  
Dsc Measurements ◽  
Infrared Measurement ◽  
Oligomeric Silsesquioxane ◽  
Tga And Dsc

Compositing is an interesting strategy that has always been employed to introduce or enhance desired functionalities in material systems. In this paper, sponges containing polypropylene, lignin, and octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) were successfully prepared via an easy and elegant strategy called thermally induced phase separation (TIPS). To fully explore the behaviour of different components of prepared sponges, properties were characterized by a thermogravimetric analyser (TGA), differential scanning calorimetry (DSC), Fourier transform infrared measurement (FTIR), and scanning electron microscopy (SEM). Furthermore, wettability properties toward an organic liquid and oil were investigated. The FTIR analysis confirmed the chemical modification of the components. TGA and DSC measurements revealed thermal stability was much better with an increase in OV-POSS content. OV-POSS modified sponges exhibited ultra-hydrophobicity and high oleophilicity with water contact angles of more than 125°. The SEM revealed that POSS molecules acted as a support for reduced surface roughness. Moreover, OV-POSS-based blend sponges showed higher sorption capacities compared with other blend sponges without OV-POSS. The new blend sponges demonstrated a potential for use as sorbent engineering materials in water remediation.

A Theoretical Analysis of CO2 Absorption in Sun Versus Shade Leaves

1978 ◽  
Vol 100 (1) ◽  
pp. 20-24 ◽  
Author(s):  
R. H. Rand
Keyword(s):  
Experimental Data ◽  
Quantitative Estimate ◽  
Geometric Model ◽  
Model Parameters ◽  
Co2 Absorption ◽  
Temperature Model ◽  
Spongy Mesophyll ◽  
One Dimensional ◽  
Mesophyll Tissue ◽  
Shade Leaves

A one-dimensional, steady-state, constant temperature model of diffusion and absorption of CO2 in the intercellular air spaces of a leaf is presented. The model includes two geometrically distinct regions of the leaf interior, corresponding to palisade and spongy mesophyll tissue, respectively. Sun, shade, and intermediate light leaves are modeled by varying the thicknesses of these two regions. Values of the geometric model parameters are obtained by comparing geometric properties of the model with experimental data of other investigators found from dissection of real leaves. The model provides a quantitative estimate of the extent to which the concentration of gaseous CO2 varies locally within the leaf interior.

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