STUDY OF AMINO ACID MODIFIERS IN GUAYULE NATURAL RUBBER

2015 ◽  
Vol 88 (2) ◽  
pp. 310-323 ◽  
Author(s):  
Colleen McMahan ◽  
Dhondup Lhamo
Keyword(s):  
Amino Acids ◽  
Natural Rubber ◽  
Oxidative Stability ◽  
Chemical Properties ◽  
The United States ◽  
Thermal Oxidative Stability ◽  
Green Strength ◽  
Strain Induced Crystallization ◽  
New Perspective ◽  
Physical And Chemical

ABSTRACT Guayule, a desert shrub indigenous to the United States, is under development as a source of natural rubber that can be used in place of petroleum-based rubber or Hevea rubber. In natural rubbers, physical and chemical properties can be strongly affected by nonrubber constituents, typically proteins and lipids, present in the material, depending on the plant species and postharvest processing. Hevea natural rubber typically contains high levels of nonrubber constituents that contribute to thermal-oxidative stability, cure acceleration, and especially strain-induced crystallization. The latter has been attributed to compound properties that render Hevea natural rubber uniquely suited for the most demanding rubber applications (e.g., aircraft tires). Hevea proteins are susceptible to hydrolysis, releasing free amino acids into the latex, which can affect rubber and compound properties. Here, low-protein guayule latex was blended with a series of amino acids varying in chemical structure. Bulk viscosity was reduced, thermal-oxidative stability was improved, and cure rate was influenced by the addition of amino acids. Generally, gel formation, green strength, and tensile strength were not affected. The results introduce a new perspective for amino acids as biobased rubber compound additives and provide insights into naturally occurring nonrubber constituents' interaction with natural rubber polymers.

EFFECT OF PROTEIN ADDITION ON PROPERTIES OF GUAYULE NATURAL RUBBER

2017 ◽  
Vol 90 (2) ◽  
pp. 387-404 ◽  
Author(s):  
Dhondup Lhamo ◽  
Colleen McMahan
Keyword(s):  
Amino Acids ◽  
Natural Rubber ◽  
Oxidative Stability ◽  
Chemical Properties ◽  
Green Strength ◽  
Truck Tires ◽  
Oxidative Resistance ◽  
Strain Induced Crystallization ◽  
General Protein ◽  
Physical And Chemical

ABSTRACT Parthenium argentatum, commonly known as guayule, is a desert shrub cultivated as a domestic source of natural rubber in the semi-arid southwestern United States. Guayule natural rubber (GR) may be used to replace petroleum-based rubber or in place of Hevea natural rubber (NR), but substitution must take into consideration differences in physical and chemical properties. Currently, Hevea NR is required in tire applications, especially aircraft and truck tires, because of its high oxidative resistance, rapid cure rate, and exceptional stress–strain response. These outstanding features are attributed to the presence of nonrubber constituents, mainly proteins and lipids, which cause the rubber to gel, and they contribute to strain-induced crystallization. In contrast, GR is low in proteins and is thus deprived of some attributes of Hevea. Addition of amino acids and proteins to guayule could potentially improve performance and thereby widen the range of applications for use. In a previous study, amino acids blended with GR latex improved thermo-oxidative stability, served as plasticizers and cure accelerators, and enhanced green strength slightly, but tensile strength was not improved. Here, a series of bio-based commercial proteins (gelatin, soy, albumin, casein, zein, gliadin, and gluten) were added to GR as a latex blend. In general, protein addition reduced bulk viscosity and improved thermo-oxidative stability. The gel content and green strength of the polymer–protein blends were increased, with the exception of gliadin, but not to levels observed for Hevea. Effects on vulcanization and mechanical properties in compounds were surprisingly influenced by the choice of antioxidants used. Our results demonstrate the potential of proteins as bio-based rubber compounding additives.

scholarly journals Assessment of Graphene Oxide and Nanoclay Based Hybrid Filler in Chlorobutyl-Natural Rubber Blend for Advanced Gas Barrier Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1098
Author(s):  
Jibin Keloth Paduvilan ◽  
Prajitha Velayudhan ◽  
Ashin Amanulla ◽  
Hanna Joseph Maria ◽  
Allisson Saiter-Fourcin ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Carbon Black ◽  
Natural Rubber ◽  
Gas Permeability ◽  
Chemical Properties ◽  
Barrier Properties ◽  
Hybrid Filler ◽  
Physical And Chemical ◽  
Chlorobutyl Rubber ◽  
And Chemical Properties

Nanomaterials have engaged response from the scientific world in recent decades due to their exceptional physical and chemical properties counter to their bulk. They have been widely used in a polymer matrix to improve mechanical, thermal, barrier, electronic and chemical properties. In rubber nanocomposites, nanofillers dispersion and the interfacial adhesion between polymer and fillers influences the composites factual properties. In the present work, a comparison of the hybrid effects of carbon black with two different nanofillers (graphene oxide and nanoclay) was studied. The 70/30 composition of chlorobutyl rubber/natural rubber elastomer blend was taken as per the blend composition optimized from our previous studies. The hybrid effects of graphene oxide and nanoclay in dispersing the nanofillers were studied mainly by analyzing nanocomposite barrier properties. The results confirm that the combined effect of carbon black with graphene oxide and nanoclay could create hybrid effects in decreasing the gas permeability. The prepared nanocomposites which partially replace the expensive chlorobutyl rubber can be used for tyre inner liner application. Additionally, the reduction in the amount of carbon black in the nanocomposite can be an added advantage of considering the environmental and economic factors.

scholarly journals Use of Physical and Chemical Properties of Commercial Tomato (Lycopersicon esculentum Mill.) Products forMonitoring Their Quality

2008 ◽  
Vol 91 (1) ◽  
pp. 112-122 ◽  
Author(s):  
Luis Eduardo Ordóñez-Santos ◽  
Enrique Arbones ◽  
Lourdes Vázquez-Oderiz ◽  
Angeles Romero-Rodríguez ◽  
Julio Gómez ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Principal Component ◽  
The United States ◽  
Soluble Solids ◽  
Multidimensional Data ◽  
Pectic Substances ◽  
Physical And Chemical Variables ◽  
Solids Content ◽  
United States Mexico ◽  
Physical And Chemical

Abstract Eighteen physical and chemical variables were determined in 25 samples of commercial tomato products: total solids, soluble solids, water activity, lycopene, 5-hydroxymethyl-2-furfural, CIELab components (L, a, b, a/b, C, H), total acidity, sodium chloride, wet-weight pulp percentage, alcohol insoluble solids, total pectic substances, ascorbic acid, and pH. In order to maximize the variability of products, samples included crushed tomato, tomato puree, tomato paste, and heavy concentrates and were taken from Italy, France, Spain, Portugal, the United States, Mexico, Colombia, and Chile. Correlation analysis and multidimensional data analysis techniques (principal component analysis and hierarchical classifications) were used to describe the products' variability and to study the relationships among variables. Three variables were selected, with the aim of classifying the collection of samples in a way consistent with the classification obtained with the first principal components. These variables were soluble solids content, the CIELab lightness parameter L, and total pectic substances content.

Review of Physical and Chemical Properties of Perfluorooctanyl sulphonate (PFOS) with Respect to its Potential Contamination on the Environment

2012 ◽  
Vol 518-523 ◽  
pp. 2183-2191 ◽  
Author(s):  
Sheng Zhang ◽  
David N Lerner
Keyword(s):  
Chemical Properties ◽  
Hydrocarbon Fuel ◽  
The United States ◽  
Breakthrough Curves ◽  
Film Forming ◽  
Perfluorinated Surfactants ◽  
Blood Banks ◽  
Single Well ◽  
Physical And Chemical ◽  
By Products

Perfluorinated surfactants have emerged as priority environmental contaminants due to their detection in environmental and biological matrices as well as concerns regarding their persistence and toxicity. They have been found in groundwater, particularly at sites used for training firefighters. They do not biodegrade easily in groundwater, and are not retarded during transport. The most common chemical is Perfluorooctanyl Sulphonate (PFOS), which is mainly used in aqueous film forming foam (AFFF) to extinguish hydrocarbon-fuel fires. It is also used in many herbicide and insecticide formulations, cosmetics, greases and lubricants, paints, polishes, and adhesives. PFOS and related fluoro-organic chemicals have been used since the 1950s. A quantity of fluorosurfactants and related products are still in use all over the world. Intensive studies over the last few years discovered that PFOS and certain by-products were both ubiquitous in the environment and highly persistent. PFOS does not biodegrade in the environment and very limited degradation has been observed in wastewater treatment. The breakthrough curves of a single-well push-pull test indicated that there was no retardation for PFOS as well. It was detected in part-per-billion levels in blood samples obtained from blood banks in the United States, Japan, Europe, and China. There have been more and more reports on the accumulation and effect of PFOS in wild animals’ liver, serum and muscle as well. This suggests that PFOS can bioaccumulate to higher levels of the food chain.

Cis-Trans Isomerization of Natural Rubber under the Influence of Organo-Aluminum Compounds and Titanium Tetrachloride

1959 ◽  
Vol 32 (4) ◽  
pp. 1036-1038 ◽  
Author(s):  
B. A. Dolgoplosk ◽  
E. N. Kropacheva ◽  
K. V. Nelson
Keyword(s):  
Natural Rubber ◽  
Ultraviolet Light ◽  
Titanium Tetrachloride ◽  
Chemical Properties ◽  
Regular Structure ◽  
Polymer Chains ◽  
Polymerization Process ◽  
Aluminum Compounds ◽  
Physical And Chemical ◽  
First Time

Abstract Ziegler catalysts have become of prime importance for synthesis of polymers with regular structure, particularly cis-polyisoprene. The disruption of the structure of the chain by the formation of trans units was, until now, connected only with the influence of the physical and chemical properties of the catalyst on the nature of the addition of the diene monomers during the polymerization process. In the present work it is shown that destruction of regularity of structure can be caused by isomerization of cis units in complete polymer chains into trans units under the influence of the compounds used for initiating the polymerization process. Attempts to isomerize natural rubber by means of ultraviolet light and iodine did not give the expected effect. Ferri established for the first time that under the influence of zinc chloride and titanium tetrachloride natural rubber undergoes changes accompanied by disappearence of crystallization on stretching as shown by x-ray structure analysis. On the basis of these results the authors presumed that under the influence of these agents isomerization of cis units to trans units occurs in the natural rubber chain. The isomerization of cis-1,4 units to trans units in polybutadiene by means of ultraviolet light in the presence of organic bromine or sulfur compounds was first accomplished and proved by Golub. The formation of trans units in natural rubber under similar conditions was not observed. The study of the isomerizing effect of TiCl4 and organo-aluminum compounds was conducted by us on solutions of milled natural rubber (NK) in benzene in sealed glass ampoules. The benzene used was dried and distilled over sodium. All work was conducted in an atmosphere of dry argon. Unsaturation and microstructure of the chain was determined on each sample. The study of microstructure of polyisoprenes was carried out by means of infrared spectra, the relative content of the different configurations of the polymer chain being determined by the absorption in the 800–1000 cm−1 region. The method previously developed by one of us was used for this purpose.

Capillary Gas Chromatographic Analysis of Amino Acids by Enantiomer Labeling

1987 ◽  
Vol 70 (2) ◽  
pp. 234-240
Author(s):  
Ernst Bayer ◽  
Hartmut Frank ◽  
Jürgen Gerhardt ◽  
Graeme Nicholson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Sea Water ◽  
Biological Fluids ◽  
Chemical Properties ◽  
Internal Standard ◽  
Optical Isomers ◽  
Internal Standards ◽  
Sample Enrichment ◽  
Physical And Chemical

Abstract The optical isomers of amino acids can be easily separated by gas chromatography using capillary columns coated with the chiral polysiloxane peptide, Chirasil-Val. Quantitative trace amino acid analysis in complex mixtures such as biological fluids, sea water, or protein hydrolysates can be achieved by enantiomer labeling: The D-amino acid enantiomers, which do not occur naturally, are added to the sample prior to analysis as internal standards. Because the D-enantiomers show the same physical and chemical properties as the natural L-enantiomers, they are ideal standard references. In routine analysis, the derivatization is achieved with a new automated derivatization robot. The D-standard serves as overall internal standard for the whole analytical procedure from sample enrichment to derivatization, chromatography, and response of the detector.

Preparation, Investigation and Study of Biological Applications of Tyrosine Derivatives against Breast Cancer Cells

2021 ◽  
Vol 19 (9) ◽  
pp. 117-125
Author(s):  
Sabrean Farhan Jawad ◽  
Dr. Nagham Mahmood Aljamali
Keyword(s):  
Amino Acids ◽  
Chemical Properties ◽  
Chemical Treatments ◽  
Tyrosine Derivatives ◽  
Anti Cancer ◽  
Physical And Chemical ◽  
Investigation And Study ◽  
Derivatives Of ◽  
Noradrenaline And Adrenaline ◽  
And Chemical Properties

Cancerous tumors are considered a serious and fatal diseases for both sexes and for all ages, even fetuses before their birth. Therefore, it has become necessary to find an alternative treatment for radiation to be safer and less dangerous than chemical treatments. Therefore, derivatives of one of the amino acids, such as tyrosine, were prepared. Tyrosine or tyrosine is one of the well-known and important amino acids for humans, and it is present in most proteins; The human body uses it to produce several types of hormones such as noradrenaline and adrenaline. In this paper, we prepared new derivatives of tyrosine represented by (four, five, six)-membered ring, then all these new tyrosine derivatives investigated by several techniques (FT.IR, H.NMR)–spectrophotometric, other physical and chemical properties, with assaying for some new created derivatives as anti-cancer.

scholarly journals NeoCoV Is Closer to MERS-CoV than SARS-CoV

2020 ◽  
Vol 13 ◽  
pp. 117863372093071
Author(s):  
Mohamed M Hassan ◽  
Mohamed A Hussain ◽  
Sumaya Kambal ◽  
Ahmed A Elshikh ◽  
Osama R Gendeel ◽  
...  
Keyword(s):  
Amino Acids ◽  
Maximum Likelihood ◽  
Phylogenetic Trees ◽  
Chemical Properties ◽  
Structural Formula ◽  
Likelihood Method ◽  
Evolutionary Changes ◽  
Whole Genomes ◽  
Physical And Chemical ◽  
The Relationship

Recently, Coronavirus has been given considerable attention from the biomedical community based on the emergence and isolation of a deadly coronavirus infecting human. To understand the behavior of the newly emerging MERS-CoV requires knowledge at different levels (epidemiologic, antigenic, and pathogenic), and this knowledge can be generated from the most related viruses. In this study, we aimed to compare between 3 species of Coronavirus, namely Middle East Respiratory Syndrome (MERS-CoV), Severe Acute Respiratory Syndrome (SARS-CoV), and NeoCoV regarding whole genomes and 6 similar proteins (E, M, N, S, ORF1a, and ORF1ab) using different bioinformatics tools to provide a better understanding of the relationship between the 3 viruses at the nucleotide and amino acids levels. All sequences have been retrieved from National Center for Biotechnology Information (NCBI). Regards to target genomes’ phylogenetic analysis showed that MERS and SARS-CoVs were closer to each other compared with NeoCoV, and the last has the longest relative time. We found that all phylogenetic methods in addition to all parameters (physical and chemical properties of amino acids such as the number of amino acid, molecular weight, atomic composition, theoretical pI, and structural formula) indicated that NeoCoV proteins were the most related to MERS-CoV one. All phylogenetic trees (by both maximum-likelihood and neighbor-joining methods) indicated that NeoCoV proteins have less evolutionary changes except for ORF1a by just maximum-likelihood method. Our results indicated high similarity between viral structural proteins which are responsible for viral infectivity; therefore, we expect that NeoCoV sooner may appear in human-related infection.

Improvements of lanthanum complex on the thermal-oxidative stability of natural rubber

2016 ◽  
Vol 51 (19) ◽  
pp. 9043-9056 ◽  
Author(s):  
Wei Zheng ◽  
Zhixin Jia ◽  
Zhuo Zhang ◽  
Wei Yang ◽  
Liqun Zhang ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Oxidative Stability ◽  
Thermal Oxidative Stability ◽  
Lanthanum Complex

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.

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