Degradative Effects of Guayule Resin on Natural Rubber. II. Kinetic Studies

1982 ◽  
Vol 55 (1) ◽  
pp. 161-180 ◽  
Author(s):  
Robert W. Keller ◽  
Howard L. Stephens
Keyword(s):  
Fatty Acids ◽  
Natural Rubber ◽  
Unsaturated Fatty Acids ◽  
Oxidative Degradation ◽  
Kinetic Studies ◽  
Qualitative Studies

Abstract Qualitative studies reported earlier and the kinetic studies reported here indicate that the unsaturated fatty acids in guayule resin are primarily responsible for the ability of guayule resin to accelerate the oxidative degradation of natural rubber. These unsaturated fatty acids apparently oxidize to form peroxide compounds which function as initiators of rubber oxidation.

Crosslinking via sulfur vulcanization of natural rubber and cellulose nanofibers incorporating unsaturated fatty acids

RSC Advances ◽  
2015 ◽  
Vol 5 (38) ◽  
pp. 29814-29819 ◽  
Author(s):  
Hayato Kato ◽  
Fumiaki Nakatsubo ◽  
Kentaro Abe ◽  
Hiroyuki Yano
Keyword(s):  
Fatty Acids ◽  
Natural Rubber ◽  
Unsaturated Fatty Acids ◽  
Cellulose Nanofibers ◽  
Sulfur Vulcanization

The reinforcement of sulfur-vulcanized natural rubber using cellulose nanofibers (CNFs) was investigated.

scholarly journals Substrate-specificities of acid and alkaline ceramidases in fibroblasts from patients with Farber disease and controls

1982 ◽  
Vol 205 (2) ◽  
pp. 419-425 ◽  
Author(s):  
Toru Momoi ◽  
Yoav Ben-Yoseph ◽  
Henry L. Nadler
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Specific Activity ◽  
Kinetic Studies ◽  
Significant Activity ◽  
Acid Ceramidase ◽  
Ph Optimum ◽  
Farber Disease ◽  
Normal Controls

The specific activity of acid ceramidase (N-acylsphingosine deacylase, EC 3.5.1.23) was measured at pH4.5 in normal fibroblasts and in fibroblasts from patients with Farber disease and obligate heterozygotes. Greater activity was found when the synthetically made ceramide substrates contained shorter-chain fatty acids or higher content of double bonds. Acid ceramidase activities towards N-lauroyl- (C12:0), N-myristoyl- (C14:0) and N-palmitoyl- (C16:0) sphingosine (C18:1) were respectively about 38, 26 and 6 times higher than the activity towards the N-stearoyl (C18:0) substrate. The activity towards N-linolenoylsphingosine (C18:3/C18:1), N-linoleoylsphingosine (C18:2/C18:1) and N-oleoylsphingosine (C18:1/C18:1) were respectively about 5, 4 and 3 times higher than the activity towards N-stearoylsphingosine (C18:0/C18:1). The activity towards N-stearoyldihydrosphingosine (C18:0/C18:0) was about 40% of that towards N-stearoylsphingosine. Fibroblast alkaline ceramidase possessed significant activity only towards ceramides of unsaturated fatty acids, with a pH optimum of about 9.0. Deficiency of acid ceramidase activity in fibroblasts from patients with Farber disease and intermediate activities in obligate heterozygotes were demonstrated with all ceramides examined except for N-hexanoylsphingosine (C6:0/C18:1), whereas alkaline ceramidase activity was unaffected. Comparative kinetic studies of acid ceramidase activity with N-lauroylsphingosine and N-oleoylsphingosine demonstrated about 5 (2–12)-fold and 7 (4–17)-fold higher Km values in fibroblasts from patients with Farber disease as compared with normal controls. N-Lauroylsphingosine, towards which acid ceramidase activity in control fibroblasts was about 10 times higher than that towards N-oleoylsphingosine, may serve as a better substrate for enzymic diagnosis of Farber disease as well as for further characterization of the catalytically defective acid ceramidase.

Evidence that unsaturated fatty acids are potent inhibitors of renal UDP-glucuronosyltransferases (UGT): kinetic studies using human kidney cortical microsomes and recombinant UGT1A9 and UGT2B7

2004 ◽  
Vol 67 (1) ◽  
pp. 191-199 ◽  
Author(s):  
Paraskevi Tsoutsikos ◽  
John O Miners ◽  
Alan Stapleton ◽  
Anthony Thomas ◽  
Benedetta C Sallustio ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Human Kidney ◽  
Kinetic Studies

Origin of Characteristic Properties of Natural Rubber—Synergistic Effect of Fatty Acids on Crystallization of cis-1,4-Polyisoprene: I, Saturated and Unsaturated Fatty Acids

1996 ◽  
Vol 69 (4) ◽  
pp. 600-607 ◽  
Author(s):  
Seiichi Kawahara ◽  
Naoyuki Nishiyama ◽  
Takashi Kakubo ◽  
Yasuyuki Tanaka
Keyword(s):  
Fatty Acids ◽  
Differential Scanning Calorimetry ◽  
Linoleic Acid ◽  
Methyl Linoleate ◽  
Stearic Acid ◽  
Natural Rubber ◽  
Unsaturated Fatty Acids ◽  
Crystallization Rate ◽  
Scanning Calorimetry ◽  
In Cis

Abstract The influence of stearic acid, linoleic acid and their methylesters on crystallization of synthetic cis-1,4-polyisoprene was investigated at the isothermal crystallization temperature of −25°C by means of differential scanning calorimetry and dilatometry. The overall crystallization rate of cis-1,4-polyisoprene increased in step with increasing stearic acid content, while the glass transition temperature of cis-1,4-polyisoprene did not change with the additive level. The addition of 1 wt % stearic acid or methyl stearate showed an acceleration effect on the initial crystallization of the polymer, while 1 wt % linoleic acid or methyl linoleate suppressed the initial crystallization. Coexistence of stearic acid and linoleic acid or stearic acid and methyl linoleate in cis-1,4-polyisoprene gave rise to a dramatic increase in the overall crystallization rate of the polymer. The characteristic properties of natural rubber were revealed to be related to the specific ratio of miscible fatty acids to immiscible fatty acids in natural rubber.

Structural Characterization of Natural Polyisoprenes: Solve the Mystery of Natural Rubber Based on Structural Study

2001 ◽  
Vol 74 (3) ◽  
pp. 355-375 ◽  
Author(s):  
Yasuyuki Tanaka
Keyword(s):  
Fatty Acids ◽  
Natural Rubber ◽  
Structural Characterization ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Terminal Group ◽  
Radical Scavenger ◽  
Branch Points

Abstract Structural characterization of naturally occurring polyisoprenes was carried out to solve the mystery of natural rubber (NR), such as the biosynthesis mechanism of rubber formation, the origin of outstanding properties of NR and the role of rubber in rubber trees. The NMR analysis, based on terpenes and polyprenols as models, disclosed the structure of both terminal groups of rubber chain. Structural evidence indicated that the biosynthesis of rubbers from Lactarius mushroom and leaves of high plants starts from trans, trans-farnesyl diphosphate or trans, trans, trans-geranylgeranyl diphosphate and terminates by dephosphorylation to form a hydroxyl terminal group. The biosynthesis of NR was presumed to start from unidentified initiating species containing two trans-isoprene units and peptide group and to terminate forming a phospholipid terminal group. The initiating group of NR associated with proteins formed branch points, which can be decomposed by enzymatic deproteinization. The branch points formed by phospholipid group were decomposed by transesterification with sodium methoxide. Rapid crystallization of NR was explained by the presence of mixed fatty acids synergistically with linked fatty acids, which were included in phospholipid. Saturated fatty acids linked to rubber chain induced crystallization, while mixed unsaturated fatty acids acted as plasticizer and accelerated the crystallization rate. This was confirmed by the preparation of model cis-polyisoprene grafted with stearic acid. The green strength of NR decreased to the same level as synthetic cis-polyisoprene after transesterification, indicating the effect of branching formed by the phospholipid terminal group and fatty acids in NR. The role of NR in Hevea trees was analyzed using NR from Hevea trees never tapped before. The formation of hard gel and oxidative degradation during the storage of NR in Hevea trees suggested that NR acted as a radical scavenger to remove hydroperoxide.

Degradative Effects of Guayule Resin on Natural Rubber

1981 ◽  
Vol 54 (1) ◽  
pp. 115-123 ◽  
Author(s):  
R. W. Keller ◽  
D. S. Winkler ◽  
H. L. Stephens
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Natural Rubber ◽  
Unsaturated Fatty Acid ◽  
Unsaturated Fatty Acids ◽  
Oxidation Mechanism ◽  
Hydrocarbon Polymers ◽  
Rubber Degradation

Abstract This study indicates that the degradative effects of guayule resin on natural rubber are due to the presence of unsaturated fatty acids in the resin. Since linoleic acid is, by far, the most abundant unsaturated fatty acid in guayule resin, it appears that linoleic acid is primarily responsible for the degradative effects of guayule resin on natural rubber. A possible mechanism to explain the acceleration of natural rubber degradation caused by linoleic acid can be developed by fitting linoleic acid into the Bolland oxidation mechanism for hydrocarbon polymers.

scholarly journals Encapsulation of Polyunsaturated Fatty Acid Esters with Solid Lipid Particles

2011 ◽  
Vol 5 ◽  
pp. LPI.S7901 ◽  
Author(s):  
Ronald Holser
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Oxidative Degradation ◽  
Thermal Characteristics ◽  
Pharmaceutical Products ◽  
Fatty Acid Esters ◽  
Scanning Calorimetry ◽  
Solid Lipid ◽  
Solid Lipid Particles ◽  
Lipid Particles

Encapsulation of structurally sensitive compounds within a solid lipid matrix provides a barrier to prooxidant compounds and effectively limits the extent of oxidative degradation. This offers a simple approach to preserve the bioactivity of labile structures. The technology was developed for cosmetic and pharmaceutical products but may be applied to additives used in food and feed formulations. The encapsulation of docosahexaenoic acid (DHA) and α-linolenic acid (ALA) was examined as model compounds of current interest in functional foods and feeds. Solid lipid particles were prepared from triglycerides containing saturated and unsaturated fatty acids and evaluated by differential scanning calorimetry. The thermal characteristics of the lipids used to form the particle were related to molecular structure and could be adjusted by selection of the appropriate component fatty acids. Encapsulation by solid lipid particles provides a method to inhibit oxidation and improve shelf life of products formulated with DHA and ALA.

Origin of Characteristic Properties of Natural Rubber—Effect of Fatty Acids on Crystallization of cis-1,4-Polyisoprene

1998 ◽  
Vol 71 (1) ◽  
pp. 70-75 ◽  
Author(s):  
Takashi Kakubo ◽  
Ai Matsuura ◽  
Seiichi Kawahara ◽  
Yasuyuki Tanaka
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Methyl Linoleate ◽  
Natural Rubber ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Nucleating Agent ◽  
Hydroxyl Group ◽  
Fatty Acids Composition ◽  
Rapid Crystallization

Abstract Natural rubber (NR) contains linked fatty acids, composed of mainly saturated fatty acids, in conjunction with a mixture of free saturated and unsaturated fatty acids. The crystallization of synthetic cis-1,4-polyisoprene (IR) is accelerated by the addition of 1 wt % mixture of saturated fatty acid as a nucleating agent and unsaturated fatty acid as a plasticizer. As an NR model, IR was esterified with stearic acid selectively at the 3,4-isoprene units after introduction of hydroxyl group by hydroboration. The linked stearoyl group stimulated the crystallization of IR at −25 °C, while linked fatty acids other than stearoyl group showed no stimulating effect on the crystallization. The addition of methyl linoleate to the stearoyl-esterified IR gave the highest rate of crystallization at −25°C. A rapid crystallization of NR is presumed to originate from the mixed saturated and unsaturated fatty acids composition present and the presence of saturated fatty acids linked to NR.

Composition of Color Substances of Hevea Brasiliensis Natural Rubber

2007 ◽  
Vol 80 (2) ◽  
pp. 212-230 ◽  
Author(s):  
Jitladda Sakdapipanich ◽  
Kittipong Insom ◽  
Nataphon Phupewkeaw
Keyword(s):  
Fatty Acids ◽  
High Resolution ◽  
Natural Rubber ◽  
Structural Characterization ◽  
Unsaturated Fatty Acids ◽  
Rubber Latex ◽  
Naturally Occurring ◽  
Bottom Fraction ◽  
Light Color

Abstract It is accepted that NR gives naturally occurring color, which restrict many applications such as light-color products. Therefore, characterization of color substances presenting in NR is very useful to develop the certain methodology to eliminate them completely or partly from NR in the future. In this work, an attempt was made to purify and characterize the color substances extracted from various fractions of Hevea rubber latex by certain methods, using high-resolution structural characterization techniques. It was found that the content of color substances extracted from fresh latex (FL), rubber cream, bottom fraction (BF), Frey Wyssling (FW) particles and STR 20 were different. Based on the high-resolution spectroscopic analyzes, it was found that the color substances extracted from NR were composed of carotenoids, tocotrienol esters, fatty alcohol esters, tocotrienols, unsaturated fatty acids, fatty alcohols, diglyceride and monoglyceride. The results will be useful for rubber-technologist to identify the origin to make obnoxious color in natural rubber, especially in some applications which are restricted by such the color.

New extracellular fatty acids in culture filtrates of Sporothrixflocculosa and S. rugulosa

1995 ◽  
Vol 73 (1) ◽  
pp. 84-87 ◽  
Author(s):  
Streeti R. Choudhury ◽  
James A. Traquair ◽  
William R. Jarvis
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Oxidative Degradation ◽  
Mass Spectrometric ◽  
Mass Spectrometric Data ◽  
Spectrometric Data ◽  
Culture Filtrates ◽  
Nuclear Magnetic Resonance Spectra ◽  
Chromatographic Mass ◽  
Methyl Caproate

Two new and rare unsaturated, extracellular fatty acids were identified in the culture filtrates of the biocontrol fungi, Sporothrixflocculosa and S. rugulosa. 16-Methyl-9E-nonadecenoic acid (1) and (Z,Z)-10,14-eicosadienoic acid (2) were characterized on the basis of infrared (IR) and nuclear magnetic resonance spectra (13C and 1N NMR), and gas chromatographic – mass spectrometric data (GC–MS). The structure of compounds 1 and 2 was confirmed by oxidative degradation to the known standards, dimethyl azelate, dimethyl succinate, dimethyl sebacate, and methyl caproate. Keywords: unsaturated fatty acids, fungi.

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