Microencapsulated Antidegradants for Extending Rubber Lifetime

1992 ◽  
Vol 65 (1) ◽  
pp. 201-210 ◽  
Author(s):  
Larry R. Evans ◽  
David A. Benko ◽  
James G. Gillick ◽  
Walter H. Waddell
Keyword(s):  
Cellulose Acetate ◽  
Migration Rate ◽  
Wall Material ◽  
Drying Process ◽  
Capsule Wall ◽  
Rubber Compounds ◽  
Process Studies ◽  
Lifetime Testing ◽  
Processing Properties ◽  
Rubber Article

Abstract Microcapsules containing rubber antidegradants were formed in a spray-drying process. Studies were carried out to select the proper wall material based on the processing properties, migration rate of the antidegradant through the capsule wall, thickness of the capsule wall, and overall capsule diameter. The resulting capsules were incorporated into a rubber article, providing a reservoir of antidegradant during the exposure lifetime. Testing of the rubber compounds with microcapsules having diameters less than 50 µm containing AN-(l,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine in a matrix of cellulose acetate showed a significant increase in the crack-free lifetime of the rubber when flexed in exposure to ozone.

scholarly journals Ultrasound-assisted emulsions with biopolymers for spray-drying of lemongrass essential oil

2021 ◽  
Vol 56 ◽  
Author(s):  
Gabriel Ribeiro Carvalho ◽  
Amanda Maria Teixeira Lago ◽  
Maria Cecília Evangelista Vasconcelos Schiassi ◽  
Priscila de Castro e Silva ◽  
Soraia Vilela Borges ◽  
...  
Keyword(s):  
Essential Oil ◽  
Spray Drying ◽  
Gum Arabic ◽  
Partial Substitution ◽  
Partial Replacement ◽  
Wall Material ◽  
Drying Process ◽  
Osa Starch ◽  
Ultrasound Assisted ◽  
Lemongrass Essential Oil

Abstract The objective of this work was to evaluate the partial replacement of gum arabic by modified starches on the spray-drying microencapsulation of lemongrass (Cymbopogon flexuosus) essential oil. The ultrasound-assisted emulsions were prepared with 30% (w/w) of wall material, 7.5% (w/w) of oil load, and 1:1 (w/w) replacement ratio for all treatments. After 16 hours, the incompatibility observed between gum arabic and octenyl succinic anhydride (OSA) starch did not affect the obtained microparticles, since the treatment with OSA starch, partially replacing gum arabic, showed the best results for the process yield and for the oil charge retention after spray-drying process, and the treatment showed Newtonian viscosity close to that of the treatment prepared with gum arabic. Maltodextrin dextrose equivalent 10 (10DE) shows an oil load similar to that of the treatment with gum arabic, while the presence of maize maltodextrin DE20 reduces the content of encapsulated oil and the efficiency of the drying process due to the adherence of particles to the chamber. Therefore, the partial substitution of gum arabic is an alternative for the formation of emulsions, for the spray-drying microencapsulation of lemongrass essential oil.

scholarly journals Research of the properties of rubber-cord composites in the presence of new adhesion promoters

2020 ◽  
Vol 82 (3) ◽  
pp. 221-226
Author(s):  
O. V. Karmanova ◽  
S. G. Tikhomirov ◽  
E. V. Lintsova ◽  
L. V. Popova
Keyword(s):  
Elevated Temperatures ◽  
Tensile Elongation ◽  
Physical And Mechanical Properties ◽  
Cobalt Content ◽  
Strength Properties ◽  
Adhesion Promoters ◽  
Serial Sample ◽  
Rubber Compounds ◽  
The Cost ◽  
Processing Properties

Studies of experimental adhesion modifiers based on a mixture of fatty acids from the production of light vegetable oils. The properties of rubber compounds and their vulcanizates obtained using experimental adhesion promoters KK with cobalt content from 7.5 to 16.5% are investigated. The plastic-elastic and vulcanization properties of the properties of breaker rubber compounds based on polyisoprene, the physical and mechanical properties of breaker rubbers and the bond strength in the “rubber-brass-plated steel cord system” were studied. When testing belt rubbers containing experienced adhesion promoters or an imported analog of Manobond 680C, the following features were revealed. The plasticity of the prototypes was in the range of 0.2-0.4. This indicates satisfactory processing properties. The Mooney viscosity of the prototypes was lower than that of the production sample. The use of experienced adhesion promoters instead of the analogue (Manobond 680C) increases the resistance to scorching. On the basis of the analysis of elastic-strength properties, it was found that in terms of the conditional tensile strength, the prototypes were inferior to the serial ones. However, rubbers containing the KK-12, KK-13.5, KK-15 promoters met the control standards. The tensile elongation at break of the experimental rubbers is higher than that of the serial sample. This may indicate the formation of a more uniform cure network in the presence of the test products. When testing rubber-metal-hard composites, it was noted that, under normal conditions, the experienced adhesion promoters have advantages over Manobond 680C. However, at elevated temperatures, under conditions of salt and steam-air aging, they are slightly inferior to Manobond 680C. It has been established that the experimental adhesion promoters provide the required set of technical properties of belt rubbers with a CO2 + content of 12–16.5% wt. Thus, it is possible to recommend the adhesion promoters KK 12, KK-13.5, KK 15 for practical use in the composition of belt rubber compounds. This will allow replacing a foreign-made product and reducing the cost of production.

Molecular Structure and Macroscopic Properties of Synthetic Cis-Poly(Isoprene)

1974 ◽  
Vol 47 (2) ◽  
pp. 342-356 ◽  
Author(s):  
V. A. Grechanovskii ◽  
I. Ya Poddubnyi ◽  
L. S. Ivanova
Keyword(s):  
Molecular Weight ◽  
Functional Groups ◽  
Chemical Structure ◽  
Sol Gel ◽  
Average Molecular Weight ◽  
Dense Network ◽  
Green Strength ◽  
Gel Fraction ◽  
Rubber Compounds ◽  
Processing Properties

Abstract By changing the sol-gel ratio and the structure of the gel fraction it is possible to obtain various grades of synthetic cis-poly(isoprene) which show promise for different applications in the tire and mechanical rubber goods industries. The processability of commercial SKI-3 rubber (at a given average molecular weight of sol) depends mainly on the structure of the gel fraction. Thus, for example, inferior processing properties of rubber compounds is associated primarily with the presence of tight gel. The content and structure of the gel fraction also significantly affect plasto-elastic properties of raw rubbers, e.g. a low plasticity of raw rubbers owes to the increased content of gel fraction. The reduced green strength of compounds based on SKI—3 rubber is accounted for by its chemical structure. Conventional methods used to change the properties of rubbers (including the variation in molecular weight, molecular weight distribution, branching degree, and variation in the content and structure of gel fraction) cannot be considered to be adequate to tackle the problem of the green strength of SKI—3 black stocks. The way to solve the problem appears to be the introduction of functional groups into the polymer chain at the stage of synthesis or processing. These functional groups should be active as to the formation of labile rubber—carbon black—rubber and/or rubber—rubber bonds. High purity of microstructure is necessary but not sufficient for obtaining the required level of green strength of compounded SKI—3. The gel fractions of SKI—3 rubber yield vulcanizates with a more dense network than the corresponding sol vulcanizates. The temperature dependence of the tensile strength is controlled by the network density of vulcanizates from high cis-1,4 poly(isoprene).

Optimization of a spray-drying process for the production of maximally viable microencapsulated Lactobacillus pentosus using a mixture of starch-pulque as wall material

LWT ◽  
2018 ◽  
Vol 95 ◽  
pp. 216-222 ◽  
Author(s):  
Zenia Hernández-López ◽  
Esmeralda Rangel-Vargas ◽  
Javier Castro-Rosas ◽  
Carlos Alberto Gómez-Aldapa ◽  
Arturo Cadena-Ramírez ◽  
...  
Keyword(s):  
Spray Drying ◽  
Wall Material ◽  
Drying Process ◽  
Lactobacillus Pentosus

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 Microencapsulation: concepts, mechanisms, methods and some applications in food technology

2014 ◽  
Vol 44 (7) ◽  
pp. 1304-1311 ◽  
Author(s):  
Pablo Teixeira da Silva ◽  
Leadir Lucy Martins Fries ◽  
Cristiano Ragagnin de Menezes ◽  
Augusto Tasch Holkem ◽  
Carla Luisa Schwan ◽  
...  
Keyword(s):  
New Technology ◽  
Correct Choice ◽  
Wall Material ◽  
Food Technology ◽  
Capsule Wall ◽  
Food Industries ◽  
Encapsulation Method ◽  
Encapsulation Methods ◽  
Release Form ◽  
Active Substances

Microencapsulation is a process in which active substances are coated by extremely small capsules. It is a new technology that has been used in the cosmetics industry as well as in the pharmaceutical, agrochemical and food industries, being used in flavors, acids, oils, vitamins, microorganisms, among others. The success of this technology is due to the correct choice of the wall material, the core release form and the encapsulation method. Therefore, in this review, some relevant microencapsulation aspects, such as the capsule, wall material, core release forms, encapsulation methods and their use in food technology will be briefly discussed.

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