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.

The Mechanical Properties and Thermodynamic Study on Polypropylene/Talc Composites

2014 ◽  
Vol 915-916 ◽  
pp. 751-754
Author(s):  
Shao Hui Wang
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Tensile Strength ◽  
Electron Microscope ◽  
Impact Strength ◽  
Scanning Electron Microscope ◽  
Stearic Acid ◽  
Crystallization Rate ◽  
Scanning Calorimetry ◽  
Scanning Electron

The composites of PP/Talc modified by stearic acid were prepared and its effect on the properties of PP/Talc composites was investigated in this paper. The tensile strength and impact strength of PP/Talc composites increased about 15% and 30% compared with pure PP respectively. Based on surface analysis by scanning electron microscope (SEM), the Talcparticles buried well in PP matrix when the Talc was coated with the stearic acid. At the same time, it was found that Talc significantly increased the crystallization temperature and crystallization rate of PP by differential scanning calorimetry (DSC).

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.

scholarly journals Fat Fraction Qualitative Characteristics for Oat-Based Products

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 93
Author(s):  
Agata Górska ◽  
Rita Brzezińska ◽  
Klaudia Chojnacka ◽  
Joanna Bryś ◽  
Ewa Ostrowska-Ligęza ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Differential Scanning Calorimetry ◽  
Unsaturated Fatty Acids ◽  
Food Product ◽  
Scanning Calorimetry ◽  
Important Indicator ◽  
Pressure Differential Scanning Calorimetry ◽  
Fat Fraction ◽  
Qualitative Characteristics

Oat-based products are characterized by high fat content with a favorable fatty acid composition. It is of great importance to control the quality of fat fraction as an important indicator of food product safety. The aim of this study was to analyze fat isolated from whole grain oatmeal, mountain oatmeal, and instant oatmeal. We determined the composition of fatty acids and the distribution of fatty acids in triacylglycerol positions using gas chromatography. The oxidative stability of the tested fat was evaluated using pressure differential scanning calorimetry. Melting profiles were determined by differential scanning calorimetry. It was found that fat isolated from oat products is a rich source of unsaturated fatty acids. In the sn-2 position of triacylglycerols, the highest share of oleic acid was found. The fat was characterized by the highest proportion of linoleic acid in the sn-1,3 positions of the triacylglycerols. It was observed that the induction time of oxidation process of fat reached the values of 28.79 min–39.07 min in a test conducted at 120 °C and 5.84 min–7.37 min at 140 °C. The analyzed melting profiles showed the presence of peaks indicating the presence of low-melting triacylglycerols containing mainly unsaturated fatty acids.

scholarly journals Explore the gene network regulating the composition of fatty acids in cottonseed

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lihong Ma ◽  
Xinqi Cheng ◽  
Chuan Wang ◽  
Xinyu Zhang ◽  
Fei Xue ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Linolenic Acid ◽  
Gene Network ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Accumulation Pattern ◽  
Time Points ◽  
Expression Characteristics

Abstract Background Cottonseed is one of the major sources of vegetable oil. Analysis of the dynamic changes of fatty acid components and the genes regulating the composition of fatty acids of cottonseed oil is of great significance for understanding the biological processes underlying biosynthesis of fatty acids and for genetic improving the oil nutritional qualities. Results In this study, we investigated the dynamic relationship of 13 fatty acid components at 12 developmental time points of cottonseed (Gossypium hirsutum L.) and generated cottonseed transcriptome of the 12 time points. At 5–15 day post anthesis (DPA), the contents of polyunsaturated linolenic acid (C18:3n-3) and saturated stearic acid (C18:0) were higher, while linoleic acid (C18:2n-6) was mainly synthesized after 15 DPA. Using 5 DPA as a reference, 15,647 non-redundant differentially expressed genes were identified in 10–60 DPA cottonseed. Co-expression gene network analysis identified six modules containing 3275 genes significantly associated with middle-late seed developmental stages and enriched with genes related to the linoleic acid metabolic pathway and α-linolenic acid metabolism. Genes (Gh_D03G0588 and Gh_A02G1788) encoding stearoyl-ACP desaturase were identified as hub genes and significantly up-regulated at 25 DPA. They seemed to play a decisive role in determining the ratio of saturated fatty acids to unsaturated fatty acids. FAD2 genes (Gh_A13G1850 and Gh_D13G2238) were highly expressed at 25–50 DPA, eventually leading to the high content of C18:2n-6 in cottonseed. The content of C18:3n-3 was significantly decreased from 5 DPA (7.44%) to 25 DPA (0.11%) and correlated with the expression characteristics of Gh_A09G0848 and Gh_D09G0870. Conclusions These results contribute to our understanding on the relationship between the accumulation pattern of fatty acid components and the expression characteristics of key genes involved in fatty acid biosynthesis during the entire period of cottonseed development.

scholarly journals Fatty acid positional distribution (sn-2 fatty acids) and phospholipid composition in Chinese breast milk from colostrum to mature stage

2018 ◽  
Vol 121 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Ke Wu ◽  
Runying Gao ◽  
Fang Tian ◽  
Yingyi Mao ◽  
Bei Wang ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Fatty Acid Profile ◽  
Unsaturated Fatty Acids ◽  
Fatty Acid Content ◽  
Positional Distribution ◽  
Phospholipid Composition ◽  
Mature Stage ◽  
Feeding Time

AbstractThis study quantified the fatty acid profile with emphasis on the stereo-specifically numbered (sn) 2 positional distribution in TAG and the composition of main phospholipids at different lactation stages. Colostrum milk (n 70), transitional milk (n 96) and mature milk (n 82) were obtained longitudinally from healthy lactating women in Shanghai. During lactation, total fatty acid content increased, with SFA dominating in fatty acid profile. A high ratio of n-6:n-3 PUFA was observed as 11:1 over lactation due to the abundance of linoleic acid in Chinese human milk. As the main SFA, palmitic acid showed absolute sn-2 selectivity, while oleic acid, linoleic acid and α-linolenic acid, the main unsaturated fatty acids, were primarily esterified at the sn-1 and sn-3 positions. Nervonic acid and C22 PUFA including DHA were more enriched in colostrum with an sn-2 positional preference. A total of three dominant phospholipids (phosphatidylethanolamine (PE), phosphatidylcholine (PC) and sphingomyelin (SM)) were analysed in the collected samples, and each showed a decline in amount over lactation. PC was the dominant compound followed by SM and PE. With prolonged breast-feeding time, percentage of PE in total phospholipids remained constant, but PC decreased, and SM increased. Results from this study indicated a lipid profile different from Western reports and may aid the development of future infant formula more suitable for Chinese babies.

scholarly journals Inhibition of steroid 5α-reductase by specific aliphatic unsaturated fatty acids

1992 ◽  
Vol 285 (2) ◽  
pp. 557-562 ◽  
Author(s):  
T Liang ◽  
S Liao
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Linoleic Acid ◽  
Linolenic Acid ◽  
Unsaturated Fatty Acids ◽  
Binding Assay ◽  
Reductase Activity ◽  
Undecylenic Acid ◽  
Gamma Linolenic Acid ◽  
Enzymic Assay

Human or rat microsomal 5 alpha-reductase activity, as measured by enzymic conversion of testosterone into 5 alpha-dihydrotestosterone or by binding of a competitive inhibitor, [3H]17 beta-NN-diethulcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one ([3H]4-MA) to the reductase, is inhibited by low concentrations (less than 10 microM) of certain polyunsaturated fatty acids. The relative inhibitory potencies of unsaturated fatty acids are, in decreasing order: gamma-linolenic acid greater than cis-4,7,10,13,16,19-docosahexaenoic acid = cis-6,9,12,15-octatetraenoic acid = arachidonic acid = alpha-linolenic acid greater than linoleic acid greater than palmitoleic acid greater than oleic acid greater than myristoleic acid. Other unsaturated fatty acids such as undecylenic acid, erucic acid and nervonic acid, are inactive. The methyl esters and alcohol analogues of these compounds, glycerols, phospholipids, saturated fatty acids, retinoids and carotenes were inactive even at 0.2 mM. The results of the binding assay and the enzymic assay correlated well except for elaidic acid and linolelaidic acid, the trans isomers of oleic acid and linoleic acid respectively, which were much less active than their cis isomers in the binding assay but were as potent in the enzymic assay. gamma-Linolenic acid had no effect on the activities of two other rat liver microsomal enzymes: NADH:menadione reductase and glucuronosyl transferase. gamma-Linolenic acid, the most potent inhibitor tested, decreased the Vmax. and increased Km values of substrates, NADPH and testosterone, and promoted dissociation of [3H]4-MA from the microsomal reductase. gamma-Linolenic acid, but not the corresponding saturated fatty acid (stearic acid), inhibited the 5 alpha-reductase activity, but not the 17 beta-dehydrogenase activity, of human prostate cancer cells in culture. These results suggest that unsaturated fatty acids may play an important role in regulating androgen action in target cells.

scholarly journals Profile of ingested fatty acids and in the duodenal digest of steers fed different diets

2010 ◽  
Vol 39 (11) ◽  
pp. 2502-2511 ◽  
Author(s):  
Luís Fernando Glasenapp de Menezes ◽  
Gilberto Vilmar Kozloski ◽  
João Restle ◽  
Ivan Luiz Brondani ◽  
Raul Dirceu Pazdiora ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Linoleic Acid ◽  
Conjugated Linoleic Acid ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Latin Square ◽  
Tropical Pasture ◽  
Ruminal Fermentation ◽  
Omega 3 ◽  
Conventional Diet

It was evaluated in this study the effect of the type of the diet on duodenal flow of long-chain fatty acids in steers. The tested diets were the following: conventional (feedlot diet composed of 60% corn silage and 40% of concentrate); winter forage silage - rye grass (Lolium multiflorum, Lam); or tropical forage silage - association of millet (Pennisetum americanum, Leeke + alexander grass, Brachiaria plantaginea). Six Charolais × Nellore crossbred steers with cannulas in duodenum were used in a 3 × 3 double Latin square. Dry material intake was similar among the groups (mean of 4,037 g/day), but the intake of total fatty acids and saturated fatty acids were higher in the group fed tropical pasture silage. On the other hand, the animals which received the conventional diet consumed higher quantity of unsaturated fatty acids. Tropical pasture silage provided higher consumption of vacenic acid (C18:1 t-11) and the winter forage silage offered higher consumption of conjugated linoleic acid. The intake of omega-6 fatty acids was higher in the group fed conventional diet and for omega-3, intake was higher in the group fed tropical pasture diet. The total fatty acid flow in the duodenum was not affected by the diets, but in all treatments it was higher than the consumed one. The animals fed diet with concentrate show the greatest changes on the profile of fatty acids during the ruminal fermentation. Conventional diets provide the highest intake of unsaturated fatty acids and the highest availability of vacenic acid in the small intestine, but they do not increase the supply of intestinal conjugated linoleic acid.

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