scholarly journals Synthesis of Novel Benzoxazines Containing Sulfur and Their Application in Rubber Compounds

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1262
Author(s):  
Acerina Trejo-Machin ◽  
João Paulo Cosas Fernandes ◽  
Laura Puchot ◽  
Suzanne Balko ◽  
Marcel Wirtz ◽  
...  
Keyword(s):  
Phenolic Resin ◽  
Condensation Reaction ◽  
Curing Kinetics ◽  
Structural Features ◽  
Rubber Compound ◽  
Scanning Calorimetry ◽  
Phenolic Resins ◽  
Rubber Compounds ◽  
Mannich Condensation ◽  
13C Nuclear Magnetic Resonance

This work reports the synthesis and successful use of novel benzoxazines as reinforcing resins in polyisoprene rubber compounds. For this purpose, three new dibenzoxazines containing one (4DTP-fa) or two heteroatoms of sulfur (3DPDS-fa and 4DPDS-fa) were synthesized following a Mannich condensation reaction. The structural features of each benzoxazine precursor were characterized by 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) and Raman. The new precursors showed well suited reactivity as characterized by differential scanning calorimetry (DSC) and rheology and were incorporated in rubber compounds. After the mixing, the curing profiles, morphologies and mechanical properties of the materials were tested. These results show that the structural feature of each isomer was significantly affecting its behavior during the curing of the rubber compounds. Among the tested benzoxazines, 3DPDS-fa exhibited the best ability to reinforce the rubber compound even compared to common phenolic resin. These results prove the feasibility to reinforce rubber compounds with benzoxazine resins as a possible alternative to replace conventional phenolic resins. This paper provides the first guide to use benzoxazines as reinforcing resins for rubber applications, based on their curing kinetics.

Factors Which Influence Autohesion of Elastomers

1981 ◽  
Vol 54 (1) ◽  
pp. 101-114 ◽  
Author(s):  
C. K. Rhee ◽  
J. C. Andries
Keyword(s):  
Molecular Weight ◽  
Adsorption Mechanism ◽  
Phenolic Resin ◽  
Critical Level ◽  
Formaldehyde Resin ◽  
Rubber Compound ◽  
Structural Requirement ◽  
Polar Groups ◽  
Rubber Compounds ◽  
Black Level

Abstract The following conclusions can be drawn from our studies: (1) An optimum molecular weight (Mn=2095) exists for t-octylphenol-formaldehyde resin to give maximum autohesion to rubber compounds. A critical level of the phenolic resin is required in a given rubber compound to make the tackifying action effective. In addition, the presence of polar groups in a resin molecule is a structural requirement in order for the resin to provide tackiness to rubber compounds. (2) The autohesion of a rubber compound decreases as the loading of processing oil increases from 5 phr to 25 phr. This behavior is independent of the type of oil. (3) The autohesion of a rubber compound decreases with increasing carbon black level, surface area, and structure. (4) Autohesion maximizes at an optimum molecular weight of rubber. (5) Humidity has a pronounced effect on the autohesion of aged SBR compounds, whereas very little effect on that of aged NR compounds. (6) A dual diffusion-adsorption mechanism is operative in autohesion.

Lignin-Based Polybenzoxazine Derived from Empty Fruit Bunch Fibers with Good Thermal and Mechanical Properties

2020 ◽  
Vol 981 ◽  
pp. 121-126
Author(s):  
Nurfatin Farhanah Rohimi ◽  
Rasidi Roslan ◽  
Nurjannah Salim ◽  
Siti Noor Hidayah Mustapha ◽  
Sarani Zakaria ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Condensation Reaction ◽  
Curing Temperature ◽  
Empty Fruit Bunch ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Promising Alternative ◽  
Mannich Condensation ◽  
Polymerization Behavior ◽  
Izod Impact

In this study, a renewable phenolic component was synthesized using empty fruit bunch fibers via microwave-assisted liquefaction known as Liquefied Empty Fruit Bunch (LEFB). LEFB can be used as phenolic derivative to replace petroleum-based phenol as it contains aromatic group in lignin that can be used as starting materials to synthesis polybenzoxazine resins. A Lignin-based benzoxazine (L-PBz) has been synthesized using a solventless approach from the reaction of LEFB, furfurylamine as the amine component and paraformaldehyde via Mannich condensation reaction. Two different ratios of LEFB:furfurylamine:paraformaldehyde which are 1:1:1 and 1:1:2 were investigated. The thermal properties and polymerization behavior of the L-PBz were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. In addition, cured-polybenzoxazine composites were also prepared by hot-pressing the uncured L-PBz at 250 °C for 4 hours, and the mechanical properties of the composites were assessed through Izod impact strength test. TGA analysis showed that, L-PBz with ratio of 1:1:1 exhibit a high char yield compared to 1:1:2 which is 47% vs 43%, respectively, after being heated until 900 °C. However, L-PBz with ratio of 1:1:2 showed good polymerization behavior compared to 1:1:1 which indicated by the curing temperature 215 °C vs 238 °C. L-PBz composites, which added with cellulose nanocrystal (CNC) fillers have better strength compared with the absence of fillers. As a conclusion, the aromatic structure of lignin in empty fruit bunch fibers has presented a promising alternative to replace petroleum-based phenol in polybenzoxazine synthesis.

Reduced Time Approach to Curing Kinetics, Part I: Dynamic Rate and Master Curve from Isothermal Data

1993 ◽  
Vol 66 (5) ◽  
pp. 849-864 ◽  
Author(s):  
T. W. Chan ◽  
G. D. Shyu ◽  
A. I. Isayev
Keyword(s):  
Kinetic Data ◽  
Master Curve ◽  
Curing Kinetics ◽  
Isothermal Kinetics ◽  
Scanning Calorimetry ◽  
Rubber Compounds ◽  
Physico Chemical ◽  
Curing Kinetic ◽  
Isothermal Kinetic ◽  
Reduced Time

Abstract A reduced time approach has been used to predict nonisothermal curing kinetics based on isothermal kinetic data. This approach makes it clear that the conversion in a kinetic process is a function of the reduced time alone and allows for the construction of a master curve from isothermal kinetic data, indicating that the dynamic (or nonisothermal ) rate is equal to the isothermal rate. The approach can be applied to curing, crystallization, and other physico-chemical kinetics. A method is also described for correcting the nonisothermal curing kinetic data obtained from differential scanning calorimetry ( DSC ) for a temperature lag between the sample and the DSC furnace. For two rubber compounds, it has been found that the nonisothermal curing kinetic data corrected for this temperature lag are in better agreement with the predictions based on isothermal kinetics than the uncorrected data.

pH-Dependent Thermal Stability of Vibrio cholerae L-asparaginase

2019 ◽  
Vol 26 (10) ◽  
pp. 743-750 ◽  
Author(s):  
Remya Radha ◽  
Sathyanarayana N. Gummadi
Keyword(s):  
Vibrio Cholerae ◽  
Conformational Changes ◽  
Kinetic Studies ◽  
Structural Features ◽  
Structure Stability ◽  
Kcal Mole ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Ph Dependent ◽  
Ph Range

Background:pH is one of the decisive macromolecular properties of proteins that significantly affects enzyme structure, stability and reaction rate. Change in pH may protonate or deprotonate the side group of aminoacid residues in the protein, thereby resulting in changes in chemical and structural features. Hence studies on the kinetics of enzyme deactivation by pH are important for assessing the bio-functionality of industrial enzymes. L-asparaginase is one such important enzyme that has potent applications in cancer therapy and food industry.Objective:The objective of the study is to understand and analyze the influence of pH on deactivation and stability of Vibrio cholerae L-asparaginase.Methods:Kinetic studies were conducted to analyze the effect of pH on stability and deactivation of Vibrio cholerae L-asparaginase. Circular Dichroism (CD) and Differential Scanning Calorimetry (DSC) studies have been carried out to understand the pH-dependent conformational changes in the secondary structure of V. cholerae L-asparaginase.Results:The enzyme was found to be least stable at extreme acidic conditions (pH< 4.5) and exhibited a gradual increase in melting temperature from 40 to 81 °C within pH range of 4.0 to 7.0. Thermodynamic properties of protein were estimated and at pH 7.0 the protein exhibited ΔG37of 26.31 kcal mole-1, ΔH of 204.27 kcal mole-1 and ΔS of 574.06 cal mole-1 K-1.Conclusion:The stability and thermodynamic analysis revealed that V. cholerae L-asparaginase was highly stable over a wide range of pH, with the highest stability in the pH range of 5.0–7.0.

Porous Structure and Transport Properties of a Carbonized Phenolic Resin

1995 ◽  
Vol 60 (2) ◽  
pp. 172-187 ◽  
Author(s):  
Pavel Fott ◽  
František Kolář ◽  
Zuzana Weishauptová
Keyword(s):  
Porous Structure ◽  
Transport Properties ◽  
Phenolic Resin ◽  
Arrhenius Equation ◽  
Mercury Porosimetry ◽  
Micropore Volume ◽  
Microporous Structure ◽  
Wetting And Drying ◽  
Phenolic Resins ◽  
Kinetics Of

On carbonizing phenolic resins, the development of porous structure takes place which influences the transport properties of carbonized materials. To give a true picture of this effect, specimens in the shape of plates were prepared and carbonized at various temperatures. The carbonizates obtained were studied by adsorption methods, electron microscopy, and mercury porosimetry. Diffusivities were evaluated in terms of measuring the kinetics of wetting and drying. It was found out that the porous structure of specimens in different stages of carbonization is formed mostly by micropores whose volumes were within 0.06 to 0.22 cm3/g. The maximum micropore volume is reached at the temperature of 750 °C. The dependence of diffusivity on the carbonization temperature is nearly constant at first, begins to increase in the vicinity of 400 °C, and at 600 °C attains its maximum. The experimental results reached are in agreement with the conception of the development and gradual closing of the microporous structure in the course of carbonization. The dependence of diffusivity on temperature can be expressed by the Arrhenius equation. In this connection, two possible models of mass transport were discussed.

scholarly journals Thermal and Photocatalytic Performance of Unsaturated Polyester Resins Modified with TiO2 Nanoparticles as Panel Bodies for Vehicles

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2036
Author(s):  
Miren Blanco ◽  
Cristina Monteserín ◽  
Nerea Uranga ◽  
Estíbaliz Gómez ◽  
Estíbaliz Aranzabe ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Energy Use ◽  
Near Infrared ◽  
Uv Light ◽  
Unsaturated Polyester ◽  
Curing Kinetics ◽  
Pollutant Emissions ◽  
Transport Sector ◽  
Scanning Calorimetry ◽  
Photocatalytic Effect

The transport sector is the fastest growing contributor to climate emissions and experiences the highest growth in energy use. This study explores the use of TiO2 nanoparticles for obtaining photocatalytic nanocomposites with improved infrared reflectance properties. The nanocomposites were prepared by dispersing 0–20 wt% of TiO2 nanoparticles in an unsaturated polyester resin. The effect of TiO2 on the curing kinetics was studied by differential scanning calorimetry, showing a significant delay of the curing reactions. The thermal reflectance of the modified resins was characterized by UV-Vis-NIR spectrophotometry, measuring total solar reflectance (TSR). The TiO2 greatly increased the TSR of the resin, due to the reflectance properties of the nanoparticles and the change in color of the modified resin. These nanocomposites reflect a significant part of near-infrared radiation, which can contribute to a reduction of the use of heating, ventilation, and air conditioning. Moreover, the photocatalytic effect of the TiO2 modified nanocomposites was studied by monitoring the degradation of an organic model contaminant in an aqueous medium under UV light, and the reusability of the nanocomposites was studied with 5 cycles. The developed nanocomposites are proposed as a solution for reducing global warming and pollutant emissions.

Sign in / Sign up

Export Citation Format

Share Document