The Microchemical Analysis of Rubber

1954 ◽  
Vol 27 (2) ◽  
pp. 521-527 ◽  
Author(s):  
G. H. Wyatt
Keyword(s):  
Natural Rubber ◽  
Ph Value ◽  
Copper Wire ◽  
Potassium Chromate ◽  
Small Samples ◽  
Bunsen Flame ◽  
Microchemical Analysis ◽  
Red Color ◽  
Violet Color ◽  
Spot Tests

Abstract While those who profess to be microchemists have a number of specialized techniques, it is surprising how often microchemistry is used without appreciation that this is being done. As examples in the analysis of rubber, two qualitative color tests may be mentioned that are both applicable to small samples. The first was described by Weber in 1900, but interest in it has been revised recently by Stern and by Parker and Wake. In this test the rubber is treated with bromine and then with phenol; natural rubber gives a violet color and so may be distinguished from synthetic elastomers. In the second test, due to Kirchhof, natural rubber is detected by the yellow-to-red color which it gives with trichloroacetic acid. Other reactions carried out with small quantities of rubber for identification purposes include the well known Beilstein test for halogens, in which the organic substance when heated on a copper wire imparts a green color to a Bunsen flame. This method was suggested by Newton for the detection of chloroprenes, and has been applied by Shaw in a systematic procedure for the identification of plastics in general. Spot tests have also been devised that depend on the reactions of the vapors produced by destructive distillation of the rubber being examined; for example, Neoprene gives vapors which bleach paper impregnated with potassium chromate, or the density and pH value of the distillate may be determined. The rates of reaction of natural rubber and various synthetic elastomers with mixed nitric and sulfuric acids has been shown to be characteristic and may be determined with small samples. In contrast with the above, some procedures have been called micromethods by their advocates merely because the samples used are smaller than usual. Microchemistry was clearly defined by Emich as covering the range 2 to 10 mg. of substance, and the present author's work described below should properly be termed semimicroanalysis.

Improved Deproteinization Process for Protein-Free Natural Rubber Latex

2013 ◽  
Vol 844 ◽  
pp. 474-477 ◽  
Author(s):  
Wiwat Pichayakorn ◽  
Jirapornchai Suksaeree ◽  
Wirach Taweepreda
Keyword(s):  
Natural Rubber ◽  
Negative Charge ◽  
Ph Value ◽  
Natural Rubber Latex ◽  
Solid Content ◽  
Enzyme Treatment ◽  
Distilled Water ◽  
Rubber Latex ◽  
Total Solid Content ◽  
Leaching Process

Hev b1-14 type proteins in natural rubber latex (NRL) have been identified as allergens in immunogenic responses. Several methods have been developed to reduce these proteins from NRL such as enzyme treatment, centrifugation, creaming, simple or ultrasonic leaching, and chlorination. In this work, the improvement of deproteinization of NRL was developed using the combination of enzyme treatment and leaching processes. The fresh NRL was incubated with 0.2 phr proteolytic alcalase enzyme, and preserved with 2%v/v paraben concentrate in the presence of a 2%v/v sodium lauryl ether sulfate (SLES) as a surfactant at 37°C for 24 hours, and then centrifuged. The upper rubber mass was then leached for three times with either distilled water, a 1%v/v SLES solution, or a mixture of 1%v/v SLES and 2.5%v/v ethanol, and then finally re-dispersed in distilled water. It was found that the increasing process of leaching with either 1%v/v SLES or a mixture of 1%v/v SLES and 2.5%v/v ethanol had the higher efficacy to reduce the remained protein in deproteinized NRL (DNRL). The best deproteinized process was the enzyme treatment and followed by the three times leaching process with a mixture of 1%v/v SLES and 2.5%v/v ethanol, that could completely reduce the proteins in DNRL to 0%. This DNRL had the pH value, viscosity, dry rubber content, and total solid content of 7.41, 13.82 cps, 42.57%, and 44.63%, respectively. Its particle size was 626.23 nm with low polydispersity index of 0.16. The negative charge of SLES could increase the higher negative charge of DNRL to-63.20 mV that exhibited very good physical stability during storage. In conclusions, the combination of enzyme treatment and leaching process with both SLES and ethanol was successful to produce the protein-free DNRL. This DNRL could be further used for several applications including medical skin products.

scholarly journals Physicochemical, biochemical and sensory properties for the characterization of Petrovská klobása (traditional fermented sausage)

2010 ◽  
pp. 19-31 ◽  
Author(s):  
Predrag Ikonic ◽  
Ljiljana Petrovic ◽  
Tatjana Tasic ◽  
Natalija Dzinic ◽  
Marija Jokanovic ◽  
...  
Keyword(s):  
Ph Value ◽  
Quality Standard ◽  
Fermented Sausage ◽  
Dry Fermented Sausage ◽  
Fermented Sausages ◽  
Red Color ◽  
Dry Fermented Sausages ◽  
Sensory Parameters ◽  
Hard Consistency

A study was carried out on a typical homemade Petrovsk? klobas? in order to characterize this traditional dry-fermented sausage, to provide a basis for establishing the quality standard and protecting designation of origin. This paper reviews the chemical composition, some physicochemical, proteolytic and sensory parameters of Petrovsk? klobas? made by five manufacturers chosen as representatives. Beside the differences between sausages made by different manufacturers the main properties of this traditional product were though recognized. Compared to other dry-fermented sausages Petrovsk? klobas? is characterized by a high content of protein (23.36-30.45%) and low contents of NaCl (2.99-3.28%). With some minor exceptions, the values of other chemical parameters are within the range of those observed for various dry-cured sausages. Weight loss during the processing is high (up to 45.71%) and pH value (~ 5.4) corresponds to the values for this parameter in other European traditional fermented sausages. Contents of different nitrogen fractions show that Petrovsk? klobas? undergoes significant proteolytic changes. At the end of ripening, Petrovsk? klobas? is characterized by aromatic and spicy-hot flavor, dark-red color and hard consistency.

An alternative for corn bran byproduct: fermentation using M. purpureus

2019 ◽  
Vol 50 (3) ◽  
pp. 515-527
Author(s):  
Adrielle Borges de Almeida ◽  
Thayanara Mayara de Lima ◽  
Nathalia Horrana Santos ◽  
Railany Vieira Santana ◽  
Silvelly Carvalho dos Santos ◽  
...  
Keyword(s):  
Nutritional Value ◽  
Water Solubility ◽  
Ph Value ◽  
Process Time ◽  
Total Phenolic ◽  
Primary Metabolism ◽  
Content Type ◽  
Corn Bran ◽  
Agroindustrial Waste ◽  
Red Color

Purpose The purpose of this paper is to evaluate the solid-state fermentation (SSF) of corn bran (CB) with Monascus purpureus. Design/methodology/approach The SSF was realized with CB ranged in process: time (4, 8, 12 and 16 days), inoculum ratio (105, 106 and 107 spores for mL) and temperature (16, 24 and 32 °C). Color of the CB and fermented CB (FCB) was evaluated by spectrophotometer, and this result was used to choose one treatment. The proximal composition (moisture, lipid, ash and protein content), pH value, total phenolic content, antioxidant capacity and functional properties of CB and FCB were analyzed. The carbohydrate content and caloric value were calculated for CB and FCB. Findings The color results showed that during asexual reproduction, there was inhibition of the pigment production by M. purpureus. There was an increase in the amount of lipids and a decrease in carbohydrates in SSF, thus elucidating the primary metabolism of M. purpureus. CB and FCB showed no statistical difference in either the emulsifying activity or water solubility. Originality/value SSF is an alternative for the use of unvalued agroindustrial waste, and by utilizing this process with CB, a new ingredient with red color can be produced with important nutritional value.

Effect of Non-Rubber Components on Storage Hardening and Gel Formation of Natural Rubber During Accelerated Storage under Various Conditions

2003 ◽  
Vol 76 (5) ◽  
pp. 1228-1240 ◽  
Author(s):  
Jintana Yunyongwattanakorn ◽  
Yasuyuki Tanaka ◽  
Seiichi Kawahara ◽  
Warunee Klinklai ◽  
Jitladda Sakdapipanich
Keyword(s):  
Natural Rubber ◽  
Ph Value ◽  
Natural Rubber Latex ◽  
Long Chain Fatty Acid ◽  
Gel Fraction ◽  
Constant Ph ◽  
Accelerated Storage ◽  
Low Humidity ◽  
Enzymatic Deproteinization ◽  
Clear Increase

Abstract The phenomenon of storage hardening in solid natural rubber (NR) is presumed to occur by means of reactions between some non-rubber components and abnormal groups in rubber molecule. The main non-rubber constituents in NR are composed of proteins and lipids. The storage hardening behavior of NR purified by enzymatic deproteinization and transesterification was analyzed under high and low humidity conditions using phosphorus pentoxide (P2O5) and sodium hydroxide (NaOH). The NR obtained from centrifuged fresh natural rubber latex (CFNR) and deproteinized NR latex (DPNR) showed significant increase in the hardening plasticity index (PH) value during storage; while that of the transesterified NR (TENR) and transesterified DPNR (DPTE-NR) was almost constant during storage. After keeping samples under high humidity conditions, the fresh natural rubber (FNR), CFNR and DPNR showed constant PH value, while that of the TENR and DPTE-NR decreased during storage. The FNR, CFNR and DPNR showed a clear increase in the gel fraction after the occurrence of storage hardening reaction. The gel fraction showed molecular weight between crosslinks (Mc) of about 104. Glass transition temperature (Tg) of gel fraction was higher than that observed in the case of sol fraction. The formation of crosslinking and branching during accelerated storage was presumed to be due to the chemical bonding between the active functional groups in the long-chain fatty acid of phospholipids at the terminating end of rubber molecules under low humidity conditions.

Waterborne Polyurethane: Effect of Functional Groups in Aromatic Isocyanate and the Chain Length of Hydroxyl Terminated Natural Rubber

2011 ◽  
Vol 415-417 ◽  
pp. 2032-2035
Author(s):  
Lalita Kaenhin ◽  
Pairote Klinpituksa ◽  
Adisai Rungvichaniwat ◽  
Jean Francois Pilard
Keyword(s):  
Natural Rubber ◽  
Material Properties ◽  
Chemical Structure ◽  
Ph Value ◽  
Waterborne Polyurethane ◽  
Phenyl Isocyanate ◽  
Small Particles ◽  
Suitable Material ◽  
Economic Competitiveness ◽  
Chain Lengths

Waterborne polyurethane (WPU) has its main applications in coatings and adhesives. Compared with the competing PU products from solvent-based processes, it has a more environmentally friendly manufacturing process. Its economic competitiveness could also be improved by the use of aromatic isocyanates that are widely available and cheaper than the currently used aliphatic isocyanates. We report on the synthesis and properties of WPU, based on natural rubber (NR) whose molecular structure has been altered, in combination with an aromatic isocyanate. The NR modification is by hydroxyl termination, with experiments using two chain lengths (HT600 and HT1000, named after molecular weight). The aromatic isocyanates used are 4,4’-Methylene bis (phenyl isocyanate) (MDI) and polymethylene polyphenyl polyisocyanate (p-MDI). The synthesized chemical structure is characterized using ATR-FTIR, while the key material properties reported here are the pH value, mean particle size and size distribution, and glass transition temperature. The WPU achieved suitable material properties, with small particles sizes and good dispersion, for applications in coatings.

scholarly journals A SCHIFF REAGENT OF CALIBRATED SENSITIVITY

1959 ◽  
Vol 7 (2) ◽  
pp. 93-97 ◽  
Author(s):  
HERBERT ELFTMAN
Keyword(s):  
Sulfur Dioxide ◽  
Positive Response ◽  
Spectrophotometric Analysis ◽  
Sulfurous Acid ◽  
Low Concentrations ◽  
Red Color ◽  
Violet Color ◽  
Schiff Reagent ◽  
The One ◽  
Excess Sulfur

The sensitivity of Schiff reagent for the detection of low concentrations of aldehyde increases progressively as the concentration of sulfurous acid in the reagent is lowered. Calibration of sensitivity is readily accomplished by titrating the Schiff reagent against the iodine of Lugol's solution. Stability of Schiff's solution depends on decreasing the evaporation of sulfur dioxide and of retarding the change of sulfite to sulfate. For practical purposes these ends can be achieved by storage in the refrigerator of a solution with greater sulfurous acid content and acidity than the solution used for staining. Evacuation of the excess sulfur dioxide or mixing in proper proportions with used reagent allows the rapid production of a solution of the desired sensitivity. If chemical preservatives are required, 0.5% hydroquinone gives very good results. Spectrophotometric measurement of the colored solutions produced by adding aldehyde to Schiff reagent indicates that at least two distinct compounds may result. The one that is usually mentioned as characteristic of a positive response of aldehyde to the Schiff reagent has a violet color. When the concentration of aldehyde is so low that only a Schiff solution of low sulfurous acid titer will react with it, a red color is produced. Spectrophotometric analysis shows this compound to be different from the original basic fuchsin and validates its use as an endpoint in the reaction of aldehyde with Schiff's reagent.

scholarly journals Effect of Co-Surfactants and Pasteurization for Preservation of Natural Rubber

2021 ◽  
Author(s):  
Sittiporn Punyanity ◽  
Rungsarit Koonawoot ◽  
Anucha Raksanti ◽  
Sakdiphon Thiansem ◽  
Somchai Thamsutiwat ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Ph Value ◽  
Chemical Properties ◽  
Time Range ◽  
Linear Alkylbenzene ◽  
Linear Alkylbenzene Sulfonates ◽  
Short And Long Term ◽  
Acid Producing Bacteria ◽  
Physical And Chemical

This research was a study of the effect of addition linear alkylbenzene sulfonates (LAS), NaHCO3, and NaCl and pasteurization on the preservation of natural rubber (NR). The samples were collected from rubber plantations of Chiang Rai province which were added with three surfactants in samples already. Physical and chemical properties were evaluated using pH, deterioration, viscosity, color, and odor. Then, the samples were stored at 28-30°C periods times of 0, 15, 30, 45, and 60 days. The experiment found that the color, viscosity, odor, and texture of NR samples were not spoiled after being preserved for 30 days but after 45 and 60 days found some coagulation of NR. In the case of non-preserved NR was found that spoiled NR in every period time range of 15-60 days. The pH testing found that increasing period times affect decreased pH value and increased viscosity due to salt of sulfate, carbonate, chloride, and thermal treatment of pasteurization which kill microorganisms and evaporated water. It concluded that the reagents were the process of cosurfactants with heat and frozen for increased effectiveness of anti-acid-producing bacteria and can use as short and long-term preservation of NR under the planting area condition of Thailand.

Qualitative Spot Tests for Rubber Polymers

1946 ◽  
Vol 19 (3) ◽  
pp. 832-843 ◽  
Author(s):  
H. P. Burchfield
Keyword(s):  
Natural Rubber ◽  
Filter Paper ◽  
Raw Material ◽  
Color Changes ◽  
Synthetic Rubber ◽  
Large Numbers ◽  
Confirmatory Tests ◽  
Commercially Important ◽  
Spot Tests ◽  
Representative Samples

Abstract To eliminate processing difficulties and ensure the production of standard natural and synthetic rubber reclaims, the scrap used as the raw material must be carefully segregated. When mold markings are lost, or large consignments of miscellaneous scrap are received, methods for distinguishing between the basic polymers are necessary. This paper describes a new color reaction which will serve to characterize natural rubber, GR-S, and Perbunan. Confirmatory tests included in the same operation distinguish between the remaining commercially important types. The procedure is sufficiently rapid to be practical in the testing of representative samples from carload shipments, or for establishing the identity of materials on which indecisive results are obtained by less specific methods. For the routine assortment of scrap, spot tests are proposed, which are carried out by holding impregnated filter paper strips in the smoke emitted when the sample is branded with a metal rod heated to redness. Color changes take place which indicate the nature of the polymer. One test distinguishes between natural rubber and GR-S ; a second is specific for Butyl ; a third differentiates Neoprene-GN, Neoprene-ILS, and Perbunan from one another and from the hydrocarbon rubbers. The spot reactions can be carried out very rapidly, and are particularly useful when large numbers of samples must be examined.

An Optimization Study on the Inclusion of Aluminium Hydroxide into Natural Rubber Latex as Deproteinization Agent

2013 ◽  
Vol 844 ◽  
pp. 399-405
Author(s):  
Lim Keuw Keuw Wei ◽  
Khairiah Haji Badri ◽  
Wong Chong Ban
Keyword(s):  
Fourier Transform ◽  
Natural Rubber ◽  
Protein Content ◽  
Functional Group ◽  
Ph Value ◽  
Natural Rubber Latex ◽  
Rubber Latex ◽  
Optimum Amount ◽  
Optimization Study ◽  
Preliminary Study

A preliminary study was conducted to investigate the effect of aluminum hydroxide (ATH) as a deproteinizing agent in commercial natural rubber latex (NRL) onto the physicochemical properties of the NRL. The loading of ATH in NRL was varied at 0.05 parts per hundred rubbers (phr), 0.10 phr, 0.15 phr and 0.20 phr. The optimum amount of ATH in NRL was determined from pH value, mechanical strength time (MST), protein content and Fourier Transform Infrared spectroscopy. The addition of ATH in NRL reduced the protein content of NRL (3.52%) to the lowest (1.19%) at 0.15 phr ATH. Protein-aluminate complex was detected from the FTIR spectra through peak at 3498 cm-1, referred to as C-N-H functional group.

The Weber Color Test for the Identification of Natural Rubber

1945 ◽  
Vol 18 (4) ◽  
pp. 902-904 ◽  
Author(s):  
I. F. C. Parker ◽  
W. C. Wake
Keyword(s):  
Organic Chemistry ◽  
Positive Result ◽  
Natural Rubber ◽  
Natural Product ◽  
Color Test ◽  
Gutta Percha ◽  
Synthetic Rubber ◽  
Violet Color ◽  
Color Reactions ◽  
Rubberlike Materials

Abstract The Weber color reaction, mentioned in a recent note, has become of importance in detecting natural rubber in mixtures in which it may be considerably diluted with synthetic rubber or nonrubber materials. The detailed instructions for carrying out the test are given elsewhere, and Stern has published a table which shows also the colors obtained when the test is applied to rubbers other than the natural product. It is clear from this table, and is confirmed by our experience, that the strong violet color developed is distinctive for natural rubber and gutta-percha, provided that the material has been extracted with acetone. However, color reactions in organic chemistry are rarely found to be as specific as earlier workers have claimed, and work is being carried out in these laboratories to establish the limitations of the reaction when applied to rubberlike materials. With very few exceptions, synthetic rubbers and rubberlike materials available at present do not give a positive result with this test, although very faint violet colors, which cannot be confused with a positive result, are sometimes obtained. Those giving any violet color are listed in Table I.

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