Polymer-Modified Natural Rubber

1956 ◽  
Vol 29 (3) ◽  
pp. 706-717 ◽  
Author(s):  
F. M. Merrett ◽  
R. I. Wood
Keyword(s):  
Natural Rubber ◽  
Chemical Compounds ◽  
Synthetic Polymer ◽  
Technological Properties ◽  
Cooperative Program

Abstract Earlier efforts to prepare and examine rubber-synthetic polymer compositions have made virtually no attempt to determine the nature of the products, that is, whether they were simple mixtures or chemical compounds and, if the latter, of what type, and thus to rationalize, if only broadly, their physical and technological properties in terms of their basic structures. The work now described has had this object in mind, and represents a cooperative program of research, including chemical, physical, and technological aspects.

Ozone and Sunlight Effect on Aging of Carbon Black Vulcanizates

1953 ◽  
Vol 26 (1) ◽  
pp. 127-135
Author(s):  
George E. Popp ◽  
Lynn Harbison
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Carbon Black ◽  
Natural Rubber ◽  
Size Structure ◽  
Synthetic Polymer ◽  
Ozone Exposure ◽  
Polymer Compound ◽  
Type Particle ◽  
Weather Resistance

Abstract Carbon black, regardless of type, particle size, structure, and physical properties imparted, does not affect the rate or degree of checking or cracking in natural-rubber or low-temperature polymer compounds when subjected to weather or ozone exposure. Natural rubber will withstand much longer periods of exposure than the synthetic polymer studied. A pronounced degree of ozone and weather cracking and checking will result if no antioxidant is compounded into the synthetic polymer. An MAF black-synthetic polymer compound may be substantially improved in its resistance to ozone and weather resistance by selection and application of the proper antichecking ingredients.

Molecular Structure and Properties of Polybutadiene Rubbers

1964 ◽  
Vol 37 (2) ◽  
pp. 408-433 ◽  
Author(s):  
H. Blümel
Keyword(s):  
Molecular Structure ◽  
Natural Rubber ◽  
Structural Characteristics ◽  
Molecular Structures ◽  
Structure And Properties ◽  
Technological Properties ◽  
Starting Point ◽  
Mixing Behavior ◽  
Basic Characteristics ◽  
The One

Abstract A discussion of the development, present day applications, and the advantages of polybutadienes are presented. The variations of an over-all concept in products obtained through different preparations and having various molecular structures as well as differing service and technological properties were made the starting point for the present investigations. Section 2 provides a review of the basic characteristics of the most important processes for preparing polybutadiene and the associated structural or compositional characteristics. Fourteen typical polybutadienes encompassing the entire range of polybutadienes are compared to cold rubber and natural rubber with respect to their most importance analytical and polymer values corresponding to their arrangement into preparation groups. The correlations between the technological properties of the raw rubbers, of the compounds, including the mixing behavior, and the vulcanizates on the one hand and the molecular structure composition of the rubbers upon which they are based, on the other, are discussed using detailed synopses in Sections 3 and 4. In doing this, it was important to see the principal features of the different polybutadienes compared to one another, effects of the structural characteristics and of additives on the properties of the raw rubbers, compounds, and vulcanizates, as well as the differences encountered as compared to polymers which are considered most important for use in blends (cold SBR and natural rubber). Finally, in Section 5, in summary form, the effects were treated of the individually appearing structural and compositional factors in the initial polymers on the service and technological properties of the raw rubbers, compounds, and vulcanizates.

Conformation of Stereoregular Polydienes in the Crystal State

1966 ◽  
Vol 39 (1) ◽  
pp. 14-35 ◽  
Author(s):  
Paolo Corradini
Keyword(s):  
Crystal Structure ◽  
Natural Rubber ◽  
Crystal Structures ◽  
Synthetic Polymer ◽  
Gutta Percha ◽  
Comprehensive Picture ◽  
Stereoregular Polymers ◽  
Living Organisms ◽  
Configuration And Conformation ◽  
Ziegler Natta Catalysts

Abstract The first synthetic polymer from a diene for which stereoregularity was proved was poly(2-chloro-butadiene). Two stereoregular polymers of isoprene, synthesized by living organisms, were known before: gutta-percha and natural rubber. The crystal structure of all these polymers was established in 1942 by Bunn. After the discovery of Ziegler-Natta catalysts, many stereoregular polymers of dienes were prepared. The first, polybutadiene with 1,1-trans enchainment, was described originally in 1955. Subsequently, between 1955 and 1957, the crystal structures of all the stereoregular isomers of polybutadiene were elucidated. It is now possible to make a sufficiently comprehensive picture of the chain constitution, configuration, and conformation of a great number of stereoregular polymers of dienes.

scholarly journals Application of milk thistle (Silybum marianum) in functional biscuits formulation

2019 ◽  
Vol 12 (2) ◽  
pp. 192-199
Author(s):  
Veronika Bortlíková ◽  
Lukáš Kolarič ◽  
Peter Šimko
Keyword(s):  
Wheat Flour ◽  
Chemical Compounds ◽  
Milk Thistle ◽  
Protective Effects ◽  
Technological Properties ◽  
Silybum Marianum ◽  
Good Source ◽  
Seed Flour ◽  
Significant Difference ◽  
Cereal Product

Abstract Due to the substantial protective effects of milk thistle to liver against various chemical compounds, a new healthy cereal product replacing wheat flour with milk thistle seed flour in the range of 5; 10; 15; 20; 25 and 30 % has been studied. As it has been found, milk thistle seed flour is a good source of total dietary fibre, proteins, mineral compounds and fats. During the experiments, effects of wheat flour replacement on technological properties of the dough were studied using Mixolab characteristics. From the results it can be stated that milk thistle seed flour replacement led to a decrease in water absorption and stability of dough. After baking, physical, mechanical, colour and sensorial properties of the biscuits were studied. The results have shown that even a 10 % replacement results in a significant difference at p < 0.05 in measured parameters compared to ones. However, it has been calculated that statistically insignificant replacement of wheat flour with milk thistle seed flour is up to 9.3 % with quality and sensorial parameters of the biscuits equal to those prepared from 100 % wheat flour. Thus, production of functional biscuits at these conditions is fully possible.

GR-S Emulsified with Rosin Soap

1947 ◽  
Vol 20 (1) ◽  
pp. 25-28
Author(s):  
G. R. Cuthbertson ◽  
W. S. Coe ◽  
J. L. Brady
Keyword(s):  
Natural Rubber ◽  
Fats And Oils ◽  
Synthetic Polymer ◽  
Polymerization Reaction ◽  
Rosin Soap ◽  
Double Bonds ◽  
Inhibiting Effect ◽  
Retarding Effect ◽  
Working Together

Abstract One of the most troublesome deficiencies of standard GR-S, in so far as product fabrication is concerned, is the inherent lack of tackiness or the incapability of laminated and spliced surfaces to flow and knit together easily. This was especially bothersome from 1942 to 1944, when the scarcity of natural rubber forced fabricators to use a synthetic polymer before they had developed satisfactory methods and equipment to compensate for its deficiencies. Early in 1942, in anticipation of a later scarcity of fats and oils suitable for making the soap used for emulsification, the several groups working on polymer development problems intensified their efforts to find emulsifying agents which could be made from noncritical domestic materials. Rosin was one of these. Early attempts to use it were unsuccessful, however, because the polymerization reaction was strongly retarded. Later the Hercules Powder Company and The B. F. Goodrich Company, working together, found that the retarding effect could be greatly reduced with the use of disproportionated rosin previously referred to as dehydrogenated rosin. (The treatment given to the rosin results in a molecular disproportionation of the hydrogen, with the elimination of the conjugated double bonds accountable for much of the inhibiting effect on the polymerization reaction.) This work made rosin available for use in the event of an actual scarcity of fats and oils of good quality.

scholarly journals Variation of technological properties of field natural rubber lattices from Hevea brasiliensis clones and natural rubber-based compounds

DYNA ◽  
2017 ◽  
Vol 84 (203) ◽  
pp. 80-87
Author(s):  
Diego Hernán Giraldo-Vásquez ◽  
Sandra Milena Velásquez-Restrepo
Keyword(s):  
Natural Rubber ◽  
Hevea Brasiliensis ◽  
Technological Properties

El caucho natural (NR) es un biopolímero ampliamente usado, pero la variabilidad de sus propiedades es una gran desventaja. En este trabajo se estudió la variación del contenido de caucho seco (DRC), total de sólidos (TSC), cenizas, material volátil y nitrógeno de látex de campo de NR, así como de las propiedades mecánicas de compuestos basados en láminas sólidas de NR, evaluando muestras recolectadas durante 6 meses. Las muestras se obtuvieron de tres variedades clonales de Hevea brasiliensis -IAN 710, IAN 873 and FX 3864- cultivadas en una plantación en Antioquia, Colombia. En el cultivo donde se recolectó el látex se monitorearon diariamente pluviosidad, temperatura ambiente, humedad relativa y horas de sol. Se moldearon compuestos emplenado láminas de NR, determinando sus parámetros reométricos y sus propiedades mecánicas. Se encontraron diferencias estadísticamente significativas (p<0.01) para la mayoría de las propiedades evaluadas como efecto de la variedad clonal y la época de recolección. La defoliación fue la etapa fenológica que presentó la mayor influencia sobre las propiedades del NR. Se presentan algunas recomendaciones para controlar la variación de las propiedades del NR durante la fabricación de artículos con este material.

Graft Polymers with Preset Molecular Configurations

1958 ◽  
Vol 31 (4) ◽  
pp. 829-837
Author(s):  
F. M. Merrett
Keyword(s):  
Solid State ◽  
Natural Rubber ◽  
Methyl Methacrylate ◽  
Physical Properties ◽  
Polymethyl Methacrylate ◽  
Side Chains ◽  
Technological Properties ◽  
Graft Polymers

Abstract The concept of “tailor-made” macromolecules when applied to graft polymers implies an effective correlation between the chemical and physical properties of the component parts and the technological properties of the resultant whole. Earlier experiments have indicated that, for a given graft macromolecule of natural rubber and polymethyl methacrylate, one extreme physical configuration could readily be effected in solution, viz., with the rubber trunk chains collapsed and the methyl methacrylate side chains extended. The complementary configuration—rubber chains extended and the methyl methacrylate chains collapsed—seemed equally easy of achievement. If these configurations could be carried through to the solid state then comparison of the properties of the dry rubbers would provide one such correlation between established physical configurations and resultant technological properties. The evidence for these definite configurations is briefly described below followed by preparative methods for bulk quantities of the dry rubbers and the evaluation of their technological properties.

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