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.

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.

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.

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.

DEVELOPMENT OF AN EXPERIMENTAL MODEL OF AVITAMINOSIS F

2020 ◽  
Vol 20 (2) ◽  
pp. 38-40
Author(s):  
A. Levitsky ◽  
A. Lapinska ◽  
I. Selivanskaya
Keyword(s):  
Fatty Acids ◽  
Experimental Model ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Coconut Oil ◽  
The Body ◽  
Regulatory Function ◽  
Omega 3 ◽  
White Rats ◽  
Arachidonic Acids

The article analyzes the role of essential polyunsaturated fatty acids (PUFA), especially omega-3 series in humans and animals. The biosynthesis of essential PUFA in humans and animals is very limited, so they must be consumed with food (feed). Тhe ratio of omega-3 and omega-6 PUFA is very important. Biomembranes of animal cells contain about 30% PUFA with a ratio of ω-6/ ω-3 1-2. As this ratio increases, the physicochemical properties of biomembranes and the functional activity of their receptors change. The regulatory function of essential PUFA is that in the body under the action of oxygenase enzymes (cyclooxygenase, lipoxygenase) are formed extremely active hormone-like substances (eicosanoids and docosanoids), which affect a number of physiological processes: inflammation, immunity, metabolism. Moreover, ω-6 PUFA form eicosanoids, which have pro-inflammatory, immunosuppressive properties, and ω-3 PUFAs form eicosanoids and docosanoids, which have anti-inflammatory and immunostimulatory properties. Deficiency of essential PUFA, and especially ω-3 PUFA, leads to impaired development of the body and its state of health, which are manifestations of avitaminosis F. Prevention and treatment of avitaminosis F is carried out with drugs that contain PUFA. To create new, more effective vitamin F preparations, it is necessary to reproduce the model of vitamin F deficiency. An experimental model of vitamin F deficiency in white rats kept on a fat –free diet with the addition of coconut oil, which is almost completely free of unsaturated fatty acids, and saturated fatty acids make up almost 99 % of all fatty acids was developed. The total content of ω-6 PUFA (sum of linoleic and arachidonic acids), the content of ω-3 PUFA (α-linolenic, eicosapentaenoic and docosahexaenoic acids) in neutral lipids (triglycerides and cholesterol esters) defined. Тhe content of ω-6 PUFA under the influence of coconut oil decreased by 3.3 times, and the content of ω-3 PUFA - by 7.5 times. Тhe influence of coconut oil, the content of ω-6 PUFA decreased by 2.1 times, and the content of ω-3 PUFA - by 2.8 times. The most strongly reduces the content of ω-3 PUFA, namely eicosapentaenoic, coconut oil, starting from 5 %. Consumption of FFD with a content of 15 % coconut oil reduces the content of eicosapentaenoic acid to zero, ie we have an absolute deficiency of one of the most important essential PUFAs, which determined the presence of vitamin F deficiency.

PHYTOCHEMICAL SCREENING, ANTIOXIDANT, ANTI-CYTOTOXIC AND ANTICANCER EFFECTS OF GALINSOGA PARVIFLORA AND VERNONIA POLYANTHES (ASTERACEAE) EXTRACTS

2020 ◽  
Vol 8 (10) ◽  
pp. 84-98
Author(s):  
Sula M. V. Feleti ◽  
Renê L. Aleluia ◽  
Suiany V. Gervásio ◽  
Jean Carlos V. Dutra ◽  
Jessica R. P. Oliveira ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Phenolic Acids ◽  
Unsaturated Fatty Acids ◽  
Biological Effects ◽  
Human Lymphocytes ◽  
Chemical Characterization ◽  
Total Content ◽  
Ags Cells ◽  
Ft Icr Ms ◽  
Ft Icr

The study was designed to investigate the chemical composition and the biological effects of G. parviflora and V. polyanthes ethanolic extracts in vitro. Total content of phenols, flavonoids and tannins was quantified by spectrophotometry; chemical characterization was permed by mass spectrometry (ESI (-) FT-ICR MS and APCI (+) FT-ICR MS analysis). Antioxidant activities were determined by FRAP and Fe2+ chelating methods. Extracts cytotoxicity was evaluated in human lymphocytes, sarcoma-180 (S-180) and human gastric adenocarcinoma (AGS) cells, by MTT assay. V. polyanthes presented higher total content of tannins and G. parviflora presented higher amount of phenols and flavonoids. Chemical characterization showed the presence of flavonoids, phenolic acids and sesquiterpene lactones in V. polyanthes extract, and steroids, phenolic acids and fatty acids (Poly Unsaturated Fatty Acids - PUFA) in G. parviflora extract. V. polyanthes extract stood out in the Fe2+ chelation test. G. parviflora extract did not present outstanding antioxidant results in the tested protocols. Both species showed a tendency to promote cytotoxicity in human lymphocyte cells. Regarding the antiproliferative effect, both species were able to reduce S-180 cell viability and G. parviflora extract showed high antiproliferative potential in the assay with AGS cells. These findings reinforce the medicinal use of these plants, as well as suggest their potential use for the development of new drugs and for the treatment of cancers.

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