Scorch Control of Carboxylic Elastomers

Abstract Carboxylic elastomers can be cured by standard compounding recipes utilizing sulfur and zinc oxide. The zinc oxide, besides aiding the sulfur cure, also gives a secondary cure through an ionic bond with the carboxyl groups. However, because of the affinity of the zinc oxide for the carboxyl group, the stocks tend to have an excessive scorch and a short shelf life. To prevent this excessive scorch the zinc oxide must be isolated from the carboxyl group until the desired cure temperature is reached. Three materials may be used to isolate the zinc oxide : 1) zinc sulfide coated zinc oxide, 2) zinc phosphate coated zinc oxide and 3) metallic alkoxide combined with the zinc oxide. The use of any of these gives scorch control without affecting final physical properties. The amount of zinc sulfide coating, zinc phosphate coating, and metallic alkoxide varies with the type of carboxylic elastomer.

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Physical Properties of Zinc Compounds Obtained by Electrolytic Method

Фізика і хімія твердого тіла ◽

10.15330/pcss.22.1.160-167 ◽

2021 ◽

Vol 22 (1) ◽

pp. 160-167

Author(s):

A.V. Lysytsya ◽

M.V. Moroz ◽

B.D. Nechyporuk ◽

B.P. Rudyk ◽

B.F. Shamsutdinov

Keyword(s):

Zinc Oxide ◽

Chemical Composition ◽

Physical Properties ◽

Zinc Sulfide ◽

Thermal Annealing ◽

Electrolyte Composition ◽

Zinc Compounds ◽

X Ray ◽

Synthesis Of Nanoparticles

The influence of the chemical composition of the electrolyte and its temperature on the process of sythesis of nanosized zinc compounds by electrolytic method using zinc electrodes was investigated. X-ray studies have been conducted and its results were used to determine the composition of the obtained nanocrystal samples and its dimensioning using the Debye and the Williamson Hall methods. Comparisons of the results of dimensioning of nanocrystals by both methods were made. Also discussed the possibilities of synthesis of nanoparticles of zinc oxide, zinc sulfide and hydrozincite by electrolytic method. It is shown, that depending on the electrolyte composition, nanocrystals of zinc oxide, zinc sulfide, hydrozincite or their mixture are obtained. The effect of thermal annealing on the samples composition and dimensioning was investigated.

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Evaluating the Physical Properties of Novel Zinc Phosphate and Zinc Polycarboxylate Cements Containing Zinc Oxide Nanoparticles

Avicenna Journal of Dental Research ◽

10.5812/ajdr.60720 ◽

2017 ◽

Vol 9 (3) ◽

pp. e60720-e60720

Author(s):

Mohammad Ali Hemmati ◽

Faeze Hamze ◽

Mostafa Fatemi ◽

Farhood Najafi ◽

Mohammad Bagher Rezvani

Keyword(s):

Zinc Oxide ◽

Physical Properties ◽

Zinc Oxide Nanoparticles ◽

Zinc Phosphate ◽

Oxide Nanoparticles

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Crosslinking Reactions of Carboxylic Elastomers

Rubber Chemistry and Technology ◽

10.5254/1.3539642 ◽

1963 ◽

Vol 36 (4) ◽

pp. 931-962 ◽

Cited By ~ 64

Author(s):

H. P. Brown

Keyword(s):

Zinc Oxide ◽

Hydrogen Bonding ◽

Epoxy Resins ◽

Zinc Phosphate ◽

Carboxyl Groups ◽

Crosslinking Reaction ◽

Salt Formation ◽

Formation Reaction ◽

Hexamethylene Diamine ◽

Crosslinking Reactions

Abstract Carboxyl groups in elastomer molecules have been shown to contribute to the crosslinking or joining of these molecules through hydrogen bonding, salt formation, reaction with diepoxides or polyepoxides including epoxy resins, reaction with diamines or polyamines, esterification with di- or poly-hydric alcohols, reaction with carbodiimides, reaction with polyimines, and by reaction with polyisocyanates. Each of these reactions alone may produce useful crosslinkages. Or, they may be used in conjunction with crosslinking reactions operating in other parts of the molecule such as sulfur or peroxide vulcanization. This has been particularly true of salt formation, especially through the use of zinc oxide, with sulfur vulcanizarions. The carboxyl groups in some instances may be generated during the crosslinking reaction. Thus polyethylacrylate may be crosslinked with hexamethylene diamine, barium hydroxide and similar reagents. Many of the reactions of the carboxyl groups in elastomers are quite rapid. For some purposes such as surface toughening of elastomer films, this may be quite useful. For others such as the vulcanization of carboxylic elastomers with zinc oxide or with recipes containing zinc oxide, this may be objectionable because of the scorchiness of the stocks. The scorchiness of vulcanizates of carboxylic elastomers involving zinc oxide may be controlled with organic acid additives or by the use of zinc oxide coated with less reactive materials such as zinc sulfide or zinc phosphate. The speed of reaction of epoxides with carboxyl containing polymers is influenced by the structure of the epoxide. The ease with which carbodiimides induce crosslinkage is dependent upon the structure of the carbodiimide.

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ANALYSIS OF THE PHYSICAL PROPERTIES AND COMPRESSIBILITY OF ZINC OXIDE (ZnO) NANOPARTICLES AS AN ALTERNATIVE INNOVATION OF THE DENTAL AMALGAM MATERIAL

Nanomechanics Science and Technology An International Journal ◽

10.1615/nanomechanicsscitechnolintj.v4.i3.40 ◽

2013 ◽

Vol 4 (3) ◽

pp. 221-225 ◽

Cited By ~ 1

Author(s):

Poppy Puspitasari

Keyword(s):

Zinc Oxide ◽

Physical Properties ◽

Zno Nanoparticles ◽

Dental Amalgam

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Hydrogenation of benzoic acid derivatives over Pt/TiO2 under mild conditions

Communications Chemistry ◽

10.1038/s42004-021-00489-z ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Miao Guo ◽

Xiangtao Kong ◽

Chunzhi Li ◽

Qihua Yang

Keyword(s):

Electron Transfer ◽

Benzoic Acid ◽

High Efficiency ◽

Carboxyl Groups ◽

Carboxyl Group ◽

Benzoic Acids ◽

Catalyst Poisoning ◽

Benzoic Acid Derivatives ◽

Mild Conditions ◽

Transfer Direction

AbstractHydrogenation of benzoic acid (BA) to cyclohexanecarboxylic acid (CCA) has important industrial and academic significance, however, the electron deficient aromatic ring and catalyst poisoning by carboxyl groups make BA hydrogenation a challenging transformation. Herein, we report that Pt/TiO2 is very effective for BA hydrogenation with, to our knowledge, a record TOF of 4490 h−1 at 80 °C and 50 bar H2, one order higher than previously reported results. Pt/TiO2 catalysts with electron-deficient and electron-enriched Pt sites are obtained by modifying the electron transfer direction between Pt and TiO2. Electron-deficient Pt sites interact with BA more strongly than electron-rich Pt sites, helping the dissociated H of the carboxyl group to participate in BA hydrogenation, thus enhancing its activity. The wide substrate scope, including bi- and tri-benzoic acids, further demonstrates the high efficiency of Pt/TiO2 for hydrogenation of BA derivatives.

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