Transparency of Rubber Compounds Containing Magnesium Carbonate

1937 ◽  
Vol 10 (2) ◽  
pp. 299-308 ◽  
Author(s):  
W. F. Bixby ◽  
E. A. Hauser
Keyword(s):  
Light Transmission ◽  
Magnesium Carbonate ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Two Samples ◽  
Fine Particle Size ◽  
Total Light ◽  
Carbonate Sample ◽  
Form Type ◽  
Formula Type

Abstract 1. Basic magnesium carbonates of the type 5MgO·4CO2·xH2O will produce transparent vulcanized rubber. 2. Neutral carbonates of the magnesite type result in stocks of poor light transmission, even at low loading. 3. The basic carbonates, although of extremely fine particle size, are definitely crystalline in structure, as revealed by x-ray analysis. 4. The sample of magnesium carbonate producing the best transparency was a Japanese variety. When 25 per cent by weight was compounded in rubber, an over-all transmission of 45 per cent was produced. None of the domestic varieties gave higher than 36 per cent, and only two samples out of the eighteen examined produced this value. 5. The best Japanese carbonate (sample 3) and the best domestic carbonate (sample 9) possessed the same structure— that of a basic magnesium carbonate of the general form type 5MgO·4CO2·xH2O. 6. The Japanese carbonate, corresponding to the formula type 5MgO·4CO2·6H2O, gave higher total light transmissions at low filler concentrations than the best domestic carbonate, corresponding to the formula 5MgO·4CO2·9H2O. 7. Mixes containing between 25 and 40 per cent by weight of basic magnesium carbonate passed the greatest amount of undeviated light. 8. The amount of undeviated light passed by samples compounded with good Japanese magnesium carbonate and good domestic carbonate was essentially the same between 25 and 40 per cent filler—about 22 per cent. 9. The tensile strength of compounds containing domestic carbonate was higher in the 25 per cent filler range than that of mixtures containing Japanese carbonate.

Transparent Rubber Compounds. The Effect of Chemical Composition of Magnesium Carbonate Fillers

1941 ◽  
Vol 14 (1) ◽  
pp. 221-226
Author(s):  
Willard F. Bixby ◽  
Howard I. Cramer
Keyword(s):  
Carbon Dioxide ◽  
Particle Size ◽  
Chemical Composition ◽  
Chemical Analysis ◽  
Light Transmission ◽  
Magnesium Carbonate ◽  
High Light ◽  
X Ray ◽  
Rubber Compounds ◽  
Carbonate Sample

Abstract From this investigation the following conclusions may be drawn. 1. The x-ray results of Bixby and Hauser have been substantiated by chemical analysis and by microscopic examination. The magnesium carbonate productive of highest light transmitting properties is of the type: 5MgO.4CO2.xH2O. The normal carbonate, MgCO3, gives very low transmissions. 2. The best Japanese carbonate studied (sample No. 3) is pure 5MgO.4CO2.xH2O. 3. A domestic carbonate (sample No. 20), which is also pure 5MgO.4CO2.xH2O, is commercially available and produces transparency in rubber compounds equal to that obtained with the Japanese product. 4. Domestic carbonates in general contain more carbon dioxide than is required by a 5MgO.4CO2.xH2O carbonate, and are probably mixtures of this material and of the normal carbonate, MgCO3. 5. Light transmitting properties fall rapidly as the proportion of normal carbonate, MgCO3, rises. 6. Carbonates containing less than enough carbon dioxide to provide a 5MgO.4CO2.xH2O carbonate are probably mixtures of this material and hydrated magnesium oxide, MgO.H2O. 7. In preparing basic carbonates for use in producing high light-transmitting rubber, it is better to produce a material with slightly less carbon dioxide than necessary for a 5MgO.4CO2.xH2O carbonate, rather than more. 8. Particle size is an important factor influencing light transmission, especially when the normal carbonate, MgCO3, is present. Generally speaking, especially in the size ranges encountered in these carbonates, a finely divided MgCO3 will offer greater hindrance to the passage of light than will a larger size material.

The Optical Properties of Rubber

1942 ◽  
Vol 15 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Lawrence A. Wood
Keyword(s):  
Optical Properties ◽  
Light Transmission ◽  
Unit Group ◽  
Optical Measurements ◽  
Optical Methods ◽  
Systematic Research ◽  
Thin Sections ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
The One

Abstract The general survey which has been presented here shows that, while a number of the optical properties of rubber have been investigated, the measurements of most of them have been more or less preliminary or exploratory in nature and often directed towards some immediately practical application. There appears to be ample opportunity for extended, systematic research on the optical properties for their own sake. The results to be expected from such study may lead in two directions, each of them illustrated in a very preliminary fashion, by examples given in the present paper. The one direction is that of more fundamental knowledge of the constitution of rubber, especially when optical methods are used in conjunction with other types of measurement. An illustration already mentioned is the use of molecular refractivity to confirm the existence of a C5H8 unit containing one double bond as the unit group in rubber. Such work might well be extended as assistance in elucidating the constitution of vulcanized rubber. Another illustration is the use of infrared spectra or Raman spectra to determine the types of chemical bonds present in rubber. The other direction in which a study of the optical properties of rubber may lead is toward the direct solution of practical problems without regard for the theoretical significance of the measurements. Problems of control or analysis might be approached in this manner, since optical methods usually require only small amounts of material, and are often easily adaptable to rapid and precise measurements. Such applications have already been illustrated in preliminary form by the use of refractive index to determine amounts of combined or dissolved sulfur. The solution of practical problems by optical methods is also illustrated by the use of the photoelastic method for the analysis of stresses in rubber. Optical measurements in the past have been restricted in most cases to samples having fairly high light transmission. On this account the work has included only unvulcanized rubber and vulcanized compounds of the “pure gum” type. By the use of very thin sections or by employing methods which are based on the reflection of light rather than its transmission, it should be possible to extend the measurements to many practical rubber compounds which appear to be opaque, but which in reality are dispersions of filler particles in a matrix of transparent rubber.

Plastic Mulch Color Effects on Light Micro-environment and Watermelon Plant Growth

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 474d-474
Author(s):  
N.K. Damayanthi Ranwala ◽  
Dennis R. Decoteau
Keyword(s):  
Plant Growth ◽  
Light Transmission ◽  
Root Zone ◽  
Dry Mass ◽  
Plant Responses ◽  
Plastic Mulch ◽  
Plant Parts ◽  
Reflected Light ◽  
Total Light ◽  
Dry Mass Partitioning

This study was conducted to evaluate the spectral properties of various colored plastic color mulches and to determine the effects of upwardly reflected light from the mulch surfaces on watermelon plant growth when differences in root zone temperatures are minimized. Two-week-old watermelon plants were grown with black mulch, red-painted mulch, SRM-Red mulch (Sonoco, Inc., Harstville, S.C.), and white mulch. Total light reflection (58 μmol·m–2·s–1 in 400–700 nm) and red: far-red (R:FR = 0.44) of reflected light were lower in black mulch and highest in white mulch (634 and 0.92, respectively). Both black mulch and white mulch had same blue:red (B:R = 0.6) while white mulch had higher B:FR (0.58) in reflected light compared to black mulch (0.26). Reflective properties of red mulches were somewhat similar, and R:FR, B:R, and B:FR were 0.8, 0.2, and 0.18, respectively. However, SRM-Red mulch had highest total light (355 μmol·m–2·s–1 in 400–700 nm) transmission through the mulch, and R:FR, B:R, and B:FR were 0.84, 0.28, and 0.23, respectively. Light transmission through the other mulches was nonsignificant. Watermelon plants grown with black mulch and red mulches had higher internode lengths compared to white mulch after 20 days. Further, plants grown under black had significant higher petiole elongation accompanied with higher dry mass partitioning to petioles, and lower partitioning to roots, stems, and leaves. There was no effects of surface mulch color on total plant dry mass or photosynthesis although plants with black had higher transpiration rate. This suggests the differential regulation of dry mass partitioning among plant parts due to mulch color. The similar plant responses with black mulch and white mulch to plants treated with FR or R light at the end of photoperiod implies the involvement of phytochrome regulation of growth due to mulch surface color.

Effect on Vulcanized Rubber Compounds of Immersion in Boiling Water

1931 ◽  
Vol 4 (3) ◽  
pp. 426-436
Author(s):  
K. J. Soule
Keyword(s):  
Water Absorption ◽  
Room Temperature ◽  
Anomalous Behavior ◽  
Boiling Water ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Different Temperatures ◽  
Actual Change

Abstract Further work is very desirable on the effect of different accelerators, antioxidants, and fluxes. It is possible that their study will throw more light on the mechanism of the swelling phenomena, and also help to explain the anomalous behavior of some of the fillers tested. It would also seem to be worth while to study the action of a few selected stocks in water, at several temperatures between room temperature and 100° C., to determine if the water absorption and swelling merely increase with rising temperatures, or whether there might be an actual change in behavior at different temperatures.

Studies in the Vulcanization of Rubber. IV—A Theory of Vulcanization of Rubber

1930 ◽  
Vol 3 (4) ◽  
pp. 659-667
Author(s):  
G. R. Boggs ◽  
J. T. Blake
Keyword(s):  
Electrical Properties ◽  
Joule Effect ◽  
Vulcanized Rubber ◽  
Chemical Theory ◽  
Rubber Compounds ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract A new theory has been advanced which, it is believed, explains completely the various phenomena connected with the vulcanization of rubber. It is entirely a chemical theory based on the existence of two separate and distinct rubber compounds, soft vulcanized rubber and ebonite. The theory explains satisfactorily the aging of rubber, the variation in combined sulfur at optimum cure caused by acceleration, the kinetics of vulcanization, the characteristics of various vulcanizing agents, the thermochemistry of vulcanization, the electrical properties of rubber, the reclaiming of rubber, and the Joule effect. A brief review and discussion of the phenomena and past theories of vulcanization have also been given.

Crystallization of Vulcanized Rubber

1941 ◽  
Vol 14 (2) ◽  
pp. 347-355 ◽  
Author(s):  
Norman Bekkedahl ◽  
Lawrence A. Wood
Keyword(s):  
Practical Importance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Single Exception ◽  
Quantitative Results ◽  
The Subject ◽  
Low Sulfur Content ◽  
Low Sulfur

Abstract The formation of crystals at room temperature by stretching rubber, vulcanized or unvulcanized, has been the subject of considerable study. The crystallization of unstretched rubber at low temperatures is also well known, but with a single exception to be discussed later, the effect has commonly been considered to be limited to the unvulcanized material. In the present investigation, however, the crystallization of unstretched specimens of vulcanized rubber of low sulfur content has been accomplished. In commercial vulcanized rubber products, crystallization has not hitherto been recognized as a factor of practical importance. It is probably significant in cold climates, where some rubber products slowly undergo a great increase in rigidity and permanent set. Automobile traffic counters, for example, have been rendered inoperative by the hardening of the rubber tubing used with them. Laboratory tubing and other products made of a number of different commercial rubber compounds have become rigid after storage for some weeks in a refrigerator at about 0° C. Previous work on unvulcanized rubber showed that it can be crystallized at temperatures between + 10° and −40° C, the crystals melting in a range from about 6° to 16° C. Crystallization and fusion are accompanied by changes in volume, heat capacity, light absorption, birefringence, x-ray diffraction, and mechanical properties such as hardness. x-Ray diffraction and birefringence, of course, give the most direct evidence of crystalline structure, but in the present work change of volume, measured in a mercury-filled dilatometer, was chosen as the criterion of crystallization or fusion. Quantitative results are more easily obtained in this manner, and the experimental observations are simple. Furthermore, the method is well adapted to continuous observations over long periods of time, such as were found necessary in the present work.

scholarly journals IN VITRO ANTI-PLATELET AGGREGATION ACTIVITY OF HYDROXYPROPYL CELLULOSE–CYSTEAMINE BASED NANOPARTICLES CONTAINING CRUDE BROMELAIN

2020 ◽  
pp. 95-98
Author(s):  
DENI RAHMAT ◽  
LILIEK NURHIDAYATI ◽  
MARCELLA MARCELLA ◽  
ROS SUMARNY ◽  
DIAN RATIH LAKSMITAWATI
Keyword(s):  
Particle Size ◽  
Platelet Aggregation ◽  
Zeta Potential ◽  
Light Transmission ◽  
Hydroxypropyl Cellulose ◽  
Platelet Activity ◽  
Two Samples ◽  
Significant Difference ◽  
Aggregation Activity

Objective: The aim of the present study was to formulate bromelain into nanoparticles in order to improve its stability and activity. Methods: Crude bromelain was prepared by protein precipitation from the pineapple stem juice using ammonium sulphate at the concentration of 60% (w/v). Nanoparticles containing crude bromelain were generated using the ionic gelation method with hydroxypropyl cellulose–cysteamine (HPC-cysteamine) conjugate as a matrix. Crude bromelain was then added to the HPC-cysteamine solution for ionic interaction to construct the nanoparticles, which were then analyzed for their particle size and zeta potential. The resulting nanoparticles were mixed with adenosine diphosphate (ADP) to perform anti-platelet aggregation. Results: The nanoparticle had 928.3 nm in particle size and-7.25 mV in zeta potential. Anti-platelet activity of crude bromelain and the nanoparticles were determined with modification of light transmission aggregometry (LTA), in which ADP was used to induce an aggregation while a spectrophotometer UV-Vis was used to measure the absorbance at the wavelength of 600 nm. The result showed that crude bromelain and the nanoparticles rendered percentage inhibition of 8.00±1.17% and 48.56±11.19%, respectively. Conclusion: Based on the result of a one-way analysis of variance (ANOVA), it was concluded that there was a significant difference in percentage inhibition between the two samples. The nanoparticles demonstrated a better anti-platelet aggregation activity compared to crude bromelain.

Comparison of Two Coating Material Reflections of Hollow Light Guide Tube

2014 ◽  
Vol 1041 ◽  
pp. 412-415
Author(s):  
Lenka Janečková ◽  
Stanislav Darula ◽  
Daniela Bošová
Keyword(s):  
Light Guide ◽  
Light Transmission ◽  
Transmission Efficiency ◽  
Luminous Flux ◽  
Coating Material ◽  
Guide Tube ◽  
Coating Materials ◽  
Two Samples ◽  
Transmission Measurements ◽  
Light Guides

This paper discusses tube transmission efficiency of two straight hollow light guides. Two samples with diameter of 530 mm and length 1170 mm were investigated under the artificial sky in the laboratory at ICA SAS in Bratislava. The entering luminous flux was calculated from measured illuminance in the point located on the top of light guide. Below the bottom of the light guide was located a set of measuring points on the special construction in the shape of a cross. In these points, one by one, the elementary illuminances were measured and the luminous fluxes leaving the light guide were calculated. Paper presents methodology for laboratory light transmission measurements and discusses effects of two various coating materials on light transmission efficiency of hollow light guides.

Strain Test for Evaluation of Rubber Compounds

1949 ◽  
Vol 22 (1) ◽  
pp. 201-211 ◽  
Author(s):  
Frank L. Roth ◽  
Robert D. Stiehler
Keyword(s):  
High Precision ◽  
Chemical Reaction ◽  
Strain Measurements ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Order Chemical Reaction ◽  
Strain Testing ◽  
Order Of Magnitude ◽  
Single Sheet ◽  
Uniform Treatment

Abstract Measurements of elongation of rubber vulcanizates at a fixed stress have been made with a precision much greater than can be obtained in the usual measurements of stress at a specified elongation. Such measurements form the basis of a strain test developed to characterize rubber vulcanizates in control and research testing. Statistical analyses show that the errors introduced in the actual strain measurements are negligible compared to those introduced by variations during compounding and curing, whereas the errors introduced by the usual measurements of stress at a specified elongation are of the same order of magnitude as those for compounding and curing. The high precision of strain testing has been used to detect variations within a single sheet of vulcanized rubber and variations among sheets cured from the same compounded batch. It has been possible also to determine with a single sheet its change in stiffness or modulus with age. The uniform treatment of specimens in the strain test makes them particularly useful for precise measurements of set. Further, it has been found that the decrease in elongation with time of cure apparently follows the laws of a second-order chemical reaction; consequently it is possible to represent the data by an equation involving three vulcanization parameters.

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