Effect of the Temperature of Polymerization on the Structure of Butadiene-Styrene Copolymers

1956 ◽  
Vol 29 (2) ◽  
pp. 419-422 ◽  
Author(s):  
A. P. Sheĭnker ◽  
S. S. Medvedev
Keyword(s):  
Polymer Chain ◽  
Polymer Chains ◽  
Structural Variations ◽  
Dilatometric Method ◽  
Styrene Copolymers ◽  
Magnetic Stirrer ◽  
Different Temperatures ◽  
Infrared Spectrometer ◽  
The Subject ◽  
Butadiene Styrene

Abstract The addition of monomer molecules to the growing polymer chain during the polymerization of dienes may take place in several ways. In the polymerization of butadiene, the addition takes place in the 1,2- and 1,4-positions. In the latter case polymer chains are obtained with structural variations, e.g., the position of CH2 groups at the double bonds is cis or trans. The resulting polymer chains vary in configuration. It is of interest to determine how the configuration is affected by different conditions of polymerization. Several papers related to the subject are to be found in the literature. In this work, we studied with an infrared spectrometer the compositions of butadiene-styrene copolymers prepared at different temperatures. Also determined was the content of the various configurations of butadiene links in the polymer chains. The samples were prepared by polymerizing emulsions by the dilatometric method in the absence of oxygen. A satisfactory emulsion was obtained with a magnetic stirrer inserted into the dilatometer (Figure 1 ). The rotation of the stirrer (activated by a magnet attached to the axis of a motor under the thermostat) sucked the upper part of the liquid through the upper opening (1) and expelled it through the side opening (2); this assured emulsification.

Effect of Temperature on Ozone Cracking of Rubbers

1966 ◽  
Vol 39 (3) ◽  
pp. 643-650
Author(s):  
A. N. Gent ◽  
J. E. McGrath
Keyword(s):  
Polymer Chains ◽  
Effect Of Temperature ◽  
Ozone Molecule ◽  
Segmental Mobility ◽  
Network Chain ◽  
Styrene Copolymers ◽  
Rates Of Growth ◽  
Rate Controlling Step ◽  
Limiting Value ◽  
Butadiene Styrene

Abstract The rates of growth of single ozone cracks have been measured for vulcanizates of a series of butadiene—styrene copolymers, over a temperature range from − 5° C to 95° C. The rates appear to be determined by two mechanisms. At low temperatures, near the glass transition temperature, they are quantitatively related to the segmental mobility of the polymer. The principal rate-controlling step in this case is concluded to be movement of the polymer chains after scission to yield new surface. At high temperatures the rate approaches a limiting value of 10−3 cm/sec/mg of ozone/1. This is about 1/1000 of the maximum possible value when instantaneous reaction of one incident ozone molecule causes scission of one network chain.

Properties of Random and Block Copolymers of Butadiene and Styrene. III. Three Sequence Styrene-Butadiene-Styrene Block Polymers

1967 ◽  
Vol 40 (4) ◽  
pp. 1183-1199 ◽  
Author(s):  
C. W. Childers ◽  
G. Kraus
Keyword(s):  
Tensile Strength ◽  
Block Copolymers ◽  
Polymer Chains ◽  
Two Phase ◽  
Styrene Copolymers ◽  
Relaxation Measurements ◽  
Styrene Butadiene Styrene ◽  
Increasing Temperature ◽  
Styrene Butadiene ◽  
Butadiene Styrene

Abstract In butadiene styrene copolymers containing long block sequences chain segments associate with like segments to form a two phase structure. Properties of such polymers are dependent not only on composition and molecular weight but also on block sequence along the chain. Polymers containing two or more polystyrene blocks per molecule form networks and exhibit elastomeric properties in the uncured state resembling those of filler reinforced vulcanizates. This behavior is shown both by linear styrene-butadiene-styrene elastomers and multichain block copolymers branched in the polybutadiene blocks. A prominent loss tangent peak was observed around —40° C for the multichain polymers. Stress strain following prestretching and stress relaxation measurements indicate some shifting of polystyrene associations during stretching. Tensile strength is reduced by increasing temperature and addition of plasticizers. Reinforcement by polystyrene domains in vulcanized block copolymers is evident from tensile strength, dynamic modulus, and swelling measurements, but decreases with increased crosslinking. The number of styrene sequences in the primary molecules is less important after vulcanization as crosslinking destroys the individuality of the original polymer chains.

X-Ray Studies of Low-Temperature Polybutadiene and Butadiene-Styrene Copolymers

1949 ◽  
Vol 22 (2) ◽  
pp. 356-369 ◽  
Author(s):  
Karl E. Beu ◽  
W. B. Reynolds ◽  
C. F. Fryling ◽  
H. L. McMurry
Keyword(s):  
Molecular Weight ◽  
Low Temperature ◽  
Polymer Chains ◽  
Polymerization Temperature ◽  
X Ray ◽  
Styrene Copolymers ◽  
Emulsion Polymerizations ◽  
Diffraction Patterns ◽  
Ray Patterns ◽  
Butadiene Styrene

Abstract Although it is now generally recognized that the temperature of polymerization affects profoundly the properties of emulsion elastomers, there is very little evidence available pertaining to the cause of the variations of properties. It is felt by some that the improved properties of low-temperature elastomers can be related to variations in molecular weight and molecular-weight distribution. In this laboratory, however, the opinion has prevailed that the lower emulsion polymerization temperatures appreciably alter the fine structure of the molecules with an increase in the regularity of the polymer chains. If there were actually less branching and cross-linking in low-temperature polymers, and less 1,2-addition to monomer components, the increased order should be evident from x-ray diffraction patterns. To provide information on the above questions, x-ray studies were made with four purposes in view: (1) to determine the effect of polymerization temperature on the crystallization properties of unstretched and stretched polybutadienes; (2) to determine the influence of styrene content on the crystallization of butadiene-styrene copolymers; (3) to study some effects of compounding and vulcanization on crystallizable polybutadiene; and (4) to use the preferred orientation patterns obtained from some of these polymers for structural evaluations. To accomplish these objectives, x-ray patterns were obtained at several temperatures of some unstretched and stretched polybutadiene polymers, butadiene-styrene copolymers, and a vulcanized and compounded polybutadiene. The polybutadienes were prepared by emulsion polymerizations at 55°, 40°, 30°, 20°, 5°, −10° and −20° C. Since the −20° C polybutadiene showed the most marked crystallization patterns, the effects of compounding and of styrene addition were studied, using polymers prepared at this temperature for comparison. Three butadiene-styrene copolymers containing, respectively, 10, 20, and 30 per cent styrene in the monomer charge and one vulcanized polybutadiene compounded with Wyex carbon black were studied.

scholarly journals Migration from acrylonitrile butadiene styrene (ABS) polymer: swelling effect of food simulants compared to real foods

2021 ◽  
Author(s):  
Valeria Guazzotti ◽  
Annika Ebert ◽  
Anita Gruner ◽  
Frank Welle
Keyword(s):  
Acrylonitrile Butadiene Styrene ◽  
Polymer Swelling ◽  
Food Simulants ◽  
Diffusion Parameters ◽  
Compliance Testing ◽  
Diffusion Migration ◽  
Different Temperatures ◽  
Effect Of Food ◽  
High Concentrations ◽  
Butadiene Styrene

AbstractMaterials and articles made of acrylonitrile–butadiene–styrene (ABS) intended for contact with food must comply with the requirements of the European Plastic Regulation (EU) 10/2011, which lays down the food simulants and the time/temperature conditions to be applied for migration testing. Previous studies indicated that high concentrations of ethanol at temperatures above ambient may lead to swelling of ABS polymers resulting in increased migration. In this study migration kinetic data for a set of model substances at different temperatures were obtained using both food simulants stipulated in EU regulations and real food (milk, cream and olive oil). At the same time, the extent of polymer swelling was gravimetrically characterized after contact with simulants and different foods tested at several conditions to cover the majority of foreseeable applications of ABS. The obtained results confirmed that the use of high concentrations of ethanol–water, especially at high temperatures, causes the swelling of ABS polymers and results in significantly higher migration values compared to the tested foods as well as Tenax®. None of the real foods studied cause significant swelling of ABS. The widely used simulant 95% (v/v) aqueous ethanol proves not be suitable for compliance testing of ABS under the recommended conditions of Regulation (EU) 10/2011. Swelling of the polymer results in artificially higher diffusion coefficients or lower activation energies of diffusion. Migration prediction using polymer-specific diffusion parameters should therefore be considered to avoid over-conservative risk assessment for food contact materials and articles made of ABS.

Biologically Inspired Design: Color on Wings

1997 ◽  
Vol 479 ◽  
Author(s):  
Mohan Srinivasarao ◽  
Luis Padilla
Keyword(s):  
Potassium Chlorate ◽  
Structural Variations ◽  
Biologically Inspired ◽  
Selective Reflection ◽  
Cholesteric Phase ◽  
Butterfly Wings ◽  
The Subject ◽  
Physical Effects ◽  
Biologically Inspired Design ◽  
Color Specification

Brilliant, iridescent colors found on the bodies and wings of many birds, butterflies and moths are produced by structural variations and have been the subject of study for centuries. Such brilliant colors have been described as metallic colors due to the saturation or purity of the color produced and have attracted the attention of great scientists like Newton, Michelson and Lord Rayleigh. It was recognized early on that such colors arise from physical effects such as interference or diffraction as opposed to colors that are normally produced due to the presence of chromophores which absorb or emit light. Common examples of physical colors are some butterfly wings [1], color of Indigo snake skin [2], hummingbird feathers [3,4], arthropod cuticles [which are due to selective reflection of color from the solidified cholesteric phase of chitin crystallites] [5], gemstones like opal [6,7], and some crystals like potassium chlorate [8]. While the origins of such colors are well understood the properties of color and color specification have not received much attention.

scholarly journals Collapse of a polymer chain in a melt of incompatible polymer chains

1981 ◽  
Vol 42 (8) ◽  
pp. 1145-1150 ◽  
Author(s):  
J.F. Joanny ◽  
F. Brochard
Keyword(s):  
Polymer Chain ◽  
Polymer Chains

scholarly journals Adsorption Study for Chromium (VI) on Iraqi Bentonite

2010 ◽  
Vol 7 (1) ◽  
pp. 745-756
Author(s):  
Baghdad Science Journal
Keyword(s):  
Adsorption Isotherm ◽  
Adsorption Process ◽  
Kinetic Equations ◽  
Bentonite Clay ◽  
Sorption Process ◽  
Adsorption Study ◽  
Chromium Vi ◽  
Freundlich Adsorption Isotherm ◽  
Different Temperatures ◽  
The Subject

The subject of this research involves studying adsorption to remove hexavalent chromium Cr(VI) from aqueous solutions. Adsorption process on bentonite clay as adsorbent was used in the Cr(VI) concentration range (10-100) ppm at different temperatures (298, 303, 308 and 313)K, for different periods of time. The adsorption isotherms were obtained by obeying Langmuir and Freundlich adsorption isotherm with R2 (0.9921-0.9060) and (0.994-0.9998), respectively. The thermodynamic parameters were calculated by using the adsorption process at four different temperatures the values of ?H, ?G and ?S was [(+6.582 ? +6.547) kJ.mol-1, (-284.560 ? -343.070) kJ.mol-1 and (+0.977 ? +1.117) kJ.K-1.mol-1] respectively. This data indicates the spontaneous sorption process. The kinetic study of adsorption process was studied depending on three kinetic equations: 1- Lagergren equation 2- Morris-Weber equation 3- Reichenberg equation

Thermal Analysis of Butadiene Styrene Block Copolymers

1969 ◽  
Vol 42 (3) ◽  
pp. 918-923 ◽  
Author(s):  
J. N. Anderson ◽  
F. C. Weissert ◽  
C. J. Hunter
Keyword(s):  
Thermal Analysis ◽  
Osmium Tetroxide ◽  
Polymer Degradation ◽  
Glass Temperature ◽  
Index Method ◽  
K Value ◽  
Styrene Copolymers ◽  
Compositional Distribution ◽  
Composition Graph ◽  
Butadiene Styrene

Abstract The Gordon—Taylor—Wood relationship between composition and glass temperature has been used as the basis of a DTA method for block styrene analysis in butadiene styrene copolymers having the same microstructure and a similar compositional distribution. The determined K value of the Gordon—Taylor—Wood equation for these polymers prepared with a butyllithium catalyst is in fair agreement with values previously determined for emulsion butadiene styrene copolymers. The total styrene content of the copolymer was determined using the refractive index method, and the composition of the “non-block” segment of the copolymer was obtained from DTA measurement using a Tg as a function of composition graph The amount of block styrene can then be obtained by difference. Evidence is presented supporting the validity of the method, and the results are compared with those obtained by a chemical method which involved polymer degradation by a hydroperoxide in the presence of osmium tetroxide. The thermal analysis requires approximately one-half hour. All measurements are made on the dry polymer eliminating the necessity of redissolving the polymer as required by most other methods of analysis.

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