scholarly journals Microstructure and Lamellae Phase of Raw Natural Rubber via Spontaneous Coagulation Assisted by Sugars

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4306
Author(s):  
Wanna Bai ◽  
Jie Guan ◽  
Huan Liu ◽  
Shihong Cheng ◽  
Fuchun Zhao ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Biological Activity ◽  
Natural Rubber ◽  
Excellent Performance ◽  
Brown Sugar ◽  
Degree Of Crystallization ◽  
Traditional Process ◽  
Acid Coagulation ◽  
Environmental Challenge

Natural rubber (NR) as a renewable biopolymer is often produced by acid coagulation of fresh natural latex collected from Hevea brasiliensis. However, this traditional process is facing a huge economic and environmental challenge. Compared with the acid coagulation, spontaneous or microorganism coagulation is an ecofriendly way to obtain NR with excellent performance. To clarify the influence of different sugars on NR quality, several sugars were used to assist the coagulation process. Influence of different sugars on microstructure and cold crystallization were examined by 1H NMR, DSC, etc. The results indicated that sugars exhibit different biological activity on terminal components of fresh field latex and can influence the resultant molecular structure and basic properties. Brown sugar exhibits higher metabolic activity and is inclined to decompose the protein and phospholipids crosslinking compared with other sugars. The larger molecular weight of sugar molecule is beneficial for the formation of the stable α lamellae phase and higher overall degree of crystallization.

Crystallization of Cis-Polyisoprenes in a Capillary Rheometer. II. The Effects of Experimental Parameters and Molecular Structure

1971 ◽  
Vol 44 (1) ◽  
pp. 12-28 ◽  
Author(s):  
V. L. Folt
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Natural Rubber ◽  
Crystallization Process ◽  
Complex Function ◽  
Capillary Rheometer ◽  
Optimum Conditions ◽  
Experimental Parameters ◽  
Static Conditions

Abstract Cis-polyisoprenes are readily crystallized under the pressure and orientation forces existing in a capillary rheometer. The ease at which crystallization can be effected is a complex function of the interrelationships existing among the temperature, the molecular weight, stereoregularity, and the dimensions of the capillary. For a given cis-polyisoprene and capillary, crystallization occurs more readily as the molecular weight is increased. Decreasing the diameter of the capillary and/or increasing the length of the capillary enhances the ease at which a given cis-polyisoprene can be crystallized. Using the optimum conditions presently available, natural rubber has been crystallized at 146° C. The ease at which crystallization is effected decreases drastically as the cis-1,4 content of the polyisoprene is reduced. Trans-1,4 and 3,4 are similarly effective in retarding the crystallization process and their effects are proportional to their concentrations in the molecular chains. However, polyisoprenes which will not crystallize under static conditions at −20° C are readily crystallized in the capillary rheometer at much higher temperatures.

ANALISA KANDUNGAN BETA-GLUKAN LARUT AIR DAN LARUT ALKALI DARI TUBUH BUAH JAMUR TIRAM (Pleurotus ostreatus) DAN SHIITAKE (Lentinus edodes)

2013 ◽  
Vol 13 (3) ◽  
Author(s):  
Netty Widyastuti ◽  
Teguh Baruji ◽  
Henky Isnawan ◽  
Priyo Wahyudi ◽  
Donowati Donowati
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Immune System ◽  
Pleurotus Ostreatus ◽  
Water Soluble ◽  
Low Molecular Weight ◽  
Lentinus Edodes ◽  
Beta Glucan ◽  
Oyster Mushrooms ◽  
The Difference

Beta glucan is a polysaccharide compound, generally not soluble inwater and resistant to acid. Beta glucan is used as an immunomodulator (enhancing the immune system) in mammals is usually a beta-glucan soluble in water, easily absorbed and has a low molecular weight. Several example of beta-glucan such as cellulose (β-1 ,4-glucan), lentinan (β-1 0.6-glucan) and (β-1 ,3-glucan), pleuran (β-1, 6 and β-1 ,3-glucan) are isolated from species of fungi Basidiomycota include mushrooms (Pleurotus ostreatus) and shiitake (Lentinus edodes).The purpose of thisresearch activity is to obtain beta-glucan compound that can be dissolved in water and in alkali derived from fungi Basidiomycota, i.e, Oyster mushrooms (Pleurotus ostreatus) and shiitake (Lentinus edodes). The result of beta-glucan compared to characterize the resulting beta glucan that is molecular structure . The difference of beta glucan extraction is based on the differences in solubility of beta-glucan. Beta glucan could be water soluble and insoluble water.

scholarly journals Interaction mechanism of aloe-emodin with trypsin: molecular structure–affinity relationship and effect on biological activities

RSC Advances ◽  
2020 ◽  
Vol 10 (35) ◽  
pp. 20862-20871
Author(s):  
Guoyan Ren ◽  
He Sun ◽  
Gen Li ◽  
Jinling Fan ◽  
Lin Du ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Biological Activity ◽  
Biological Activities ◽  
Interaction Mechanism ◽  
Mechanism Of Interaction ◽  
Development And Utilization ◽  
Aloe Emodin

The mechanism of interaction between AE and trypsin was studied firstly. The biological activity of both decreased after the interaction. These results provide a basis for the development and utilization of AE.

Relation between Molecular Weights and Physical Properties of Rubber Fractions

1941 ◽  
Vol 14 (3) ◽  
pp. 580-589 ◽  
Author(s):  
G. Gee ◽  
L. R. G. Treloar
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Elastic Properties ◽  
Elastic Material ◽  
Experimental Results ◽  
Molecular Weights ◽  
High Elasticity ◽  
Latex Rubber

Abstract As high elasticity is a property possessed only by substances of high molecular weight, it is of interest to enquire into the relation between the elastic properties of a highly elastic material such as rubber and its molecular weight. An investigation on these lines has been made possible through the work of Bloomfield and Farmer, who have succeeded in separating natural rubber into fractions having different average molecular weights. The more important physical properties of these fractions have been examined with the object of determining which of the properties are dependent on molecular weight and which are not. Fairly extensive observations were made on the fractions from latex rubber referred to as Nos. 2, 3 and 4 by Bloomfield and Farmer, and some less extensive observations were carried out on the less oxygenated portion of fraction No. 1 obtained from crepe rubber (called hereafter 1b) . Before considering these experimental results, and their relation to the molecular weights of the fractions, it will be necessary to refer briefly to the methods used for the molecular-weight determinations, and to discuss the significance of the figures obtained.

Chemical Depolymerisation of Natural Rubber in Biphasic Medium

2014 ◽  
Vol 1024 ◽  
pp. 193-196
Author(s):  
Ibrahim Suhawati ◽  
Asrul Mustafa
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Chemical Structure ◽  
Inner Core ◽  
Particle Surface ◽  
Natural Rubber Latex ◽  
Carbonyl Groups ◽  
Latex Particles ◽  
Liquid Natural Rubber ◽  
Biphasic Medium

The molecular weight of natural rubber (NR) can be reduced via depolymerization reaction to produce liquid natural rubber (LNR) with a molecular weight less than 50 000 g/mol. In the reaction, hydrogen peroxide and sodium nitrite were added to natural rubber latex to initiate a redox type reaction which then breaks the NR chain. Low permeation of reagents into latex particles allows the degradation to occur greater at the latex particle surface relative to the inner core contributes to high molecular weight distribution (MWD) or polydispersity of the LNR obtained. In this recent works, the reaction was carried out in a biphasic medium consisting of water and toluene phases. Toluene swells latex particles as indicated by the SEM micrographs showing changes in the size of latex particles. This occurrence is suggested to increase the influx of reagents into the latex particles. Consequently, with higher permeation of reagents into the latex particles resulted in the decrease of molecular weight and lower polydispersity of the LNR obtained. Chemical structure analysize showed that the LNRs obtained were attached with hydroxyl and carbonyl groups.

scholarly journals Effect of Polymer Molecular Weight on the Bone Biological Activity of Biodegradable Polymer/Calcium Phosphate Cement Composites

2009 ◽  
Vol 15 (10) ◽  
pp. 3183-3191 ◽  
Author(s):  
Esther W.H. Bodde ◽  
Wouter J.E.M. Habraken ◽  
Antonios G. Mikos ◽  
Paul H.M. Spauwen ◽  
John A. Jansen
Keyword(s):  
Molecular Weight ◽  
Biological Activity ◽  
Calcium Phosphate ◽  
Calcium Phosphate Cement ◽  
Biodegradable Polymer ◽  
Cement Composites ◽  
Polymer Molecular Weight
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