Preparation and characterisation of liquid epoxidised natural rubber in latex stage by chemical degradation

2021 ◽  
Author(s):  
Nurul Hayati Yusof ◽  
Dazylah Darji ◽  
Fatimah Rubaizah Mohd Rasdi ◽  
Krishna Veni Baratha Nesan
Keyword(s):  
Natural Rubber ◽  
Chemical Degradation

Ultimate Tensile Properties of Elastomers. II. Comparison of Failure Envelopes for Unfilled Vulcanizates

1964 ◽  
Vol 37 (4) ◽  
pp. 792-807 ◽  
Author(s):  
Thor L. Smith
Keyword(s):  
Natural Rubber ◽  
Elevated Temperatures ◽  
Cross Sectional Area ◽  
Chemical Degradation ◽  
Sectional Area ◽  
Failure Envelope ◽  
Cross Sectional ◽  
Failure Envelopes ◽  
The Moment ◽  
Styrene Butadiene

Abstract The tensile stress-at-break σb (based on the initial cross-sectional area) and the corresponding ultimate extension ratio λb of unfilled vulcanizates of silicone, hydrofluorocarbon (Viton B), butyl (both sulfur-cured and resin-cured), and natural rubber were determined at many strain rates and temperatures; the latter ranged from slightly above the glass transition temperature Tg, up to a temperature somewhat below that at which chemical degradation affected the results. For each vulcanizate except natural rubber, data obtained over an extended temperature range superposed to give a time- and temperature-independent failure envelope on a plot of log (σb273/T) vs log (λb−1), where T is the test temperature in °K; for natural rubber, data obtained between 90° and 120° C superposed, but those at lower temperatures did not because of strain-induced crystallization. For each vulcanizate, data at elevated temperatures gave, or tended toward, a line of unit slope on a plot of log (λbσb273/T) vs log (λb−1), where λbσb is the breaking stress based on the cross-sectional area at the moment of rupture. The position of each line corresponded to the equilibrium modulus Ee derived from stress-strain curves. Failure envelopes previously obtained for two styrene—butadiene vulcanizates, which had different crosslink densities, superposed to give a master failure envelope on a plot of log (λbσb273/T) vs logEe(λb−1). On this type of plot, failure envelopes for all the vulcanizates except silicone and natural rubber were found to be essentially identical. At a given value of λbσb, silicone had a smaller λbλb and natural rubber a somewhat larger λbλb than the vulcanizates of the three other rubbery polymers.

Chemical degradation of epoxidized natural rubber using periodic acid: Preparation of epoxidized liquid natural rubber

2004 ◽  
Vol 95 (1) ◽  
pp. 6-15 ◽  
Author(s):  
P. Phinyocheep ◽  
C. W. Phetphaisit ◽  
D. Derouet ◽  
I. Campistron ◽  
J. C. Brosse
Keyword(s):  
Natural Rubber ◽  
Periodic Acid ◽  
Chemical Degradation ◽  
Epoxidized Natural Rubber ◽  
Liquid Natural Rubber

Controlled chemical degradation of natural rubber using periodic acid: Application for recycling waste tyre rubber

2012 ◽  
Vol 97 (5) ◽  
pp. 816-828 ◽  
Author(s):  
Faten Sadaka ◽  
Irène Campistron ◽  
Albert Laguerre ◽  
Jean-François Pilard
Keyword(s):  
Natural Rubber ◽  
Periodic Acid ◽  
Chemical Degradation ◽  
Waste Tyre

Preparation of liquid epoxidized natural rubber in latex stage by chemical degradation

2018 ◽  
Author(s):  
Nurul Hayati Yusof ◽  
Dazylah Darji ◽  
Krishna Veni Baratha Nesan ◽  
Fatimah Rubaizah Mohd Rasdi
Keyword(s):  
Natural Rubber ◽  
Chemical Degradation ◽  
Epoxidized Natural Rubber

CHEMICAL DEGRADATION OF POLYURETHANE FOAM WASTE AND ITS CROSSLINKED NATURAL RUBBER

2015 ◽  
Vol 88 (3) ◽  
pp. 437-448 ◽  
Author(s):  
Sa-Ad Riyajan ◽  
Nattanan Keawmwnee ◽  
Pramuan Tangboriboonrat
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Polyurethane Foam ◽  
Cost Effective ◽  
Chemical Degradation ◽  
Cure Rate ◽  
Elongation At Break ◽  
Environmental Friendly ◽  
Roll Mill ◽  
By Products

ABSTRACT The objective of this work was to use by-products from the chemical degradation of polyurethane foam waste (w-PUfd) and blend them with an epoxidized natural rubber (ENR), named PENR, for improving the mechanical properties of a Standard Thai rubber 5L (STR 5L). The swelling ratio in toluene of the PENR decreased as a function of w-PUfd content due to an increase in chemical interactions. After blending the PENR with the STR-5L and vulcanizing agents using two-roll mill and then compression molding at 150 °C, the effects of w-PUfd content in PENR on the properties of cured STR-5L were investigated. The cure rate index, tensile strength, and elongation at break of the cured STR-5L were improved after the addition of PENR. The swelling in toluene of cured STR-5L decreased as a function of w-PUfd in PENR. At 100 phr w-PUfd in PENR, the 20:80 PENR:STR-5L provided the highest tensile strength of ~23 MPa. These biodegradable, cured rubbers with w-PUfd content are environmental friendly and cost-effective products.

Development of Solid Rocket Propellant based on Isophorone Diisocyanate – Hydroxyl Terminated Natural Rubber Binder

2014 ◽  
Vol 69 (2) ◽  
Author(s):  
Munirah Onn ◽  
Hussin Md Nor ◽  
Wan Khairuddin Wan Ali
Keyword(s):  
Natural Rubber ◽  
Chemical Degradation ◽  
Hydroxyl Group ◽  
Molar Ratio ◽  
Combustion Characteristic ◽  
Isophorone Diisocyanate ◽  
Aluminium Powder ◽  
Liquid Natural Rubber ◽  
Solid Rocket ◽  
Type Of Failure

In this work, a novelty solid propellant based on Isophorone Diisocyanate (IPDI) with Hydroxyl Terminated Natural Rubber (HTNR) binder network was successfully developed. The preparation of Liquid Natural Rubber (LNR) by chemical degradation Deprotenized Natural Rubber (DPNR) using cobaltous was carried out. From the FTIR spectroscopy, a broad hydroxyl group peak at 3444cm-1 was obtained from HTNR. Rubber network depict a strong carbonyl group C=O at 1714cm-1 and amine group N-H at 3433cm-1. NMR analysis also proves that there was hydroxyl group presence in the sample where broad peak at range 1-3 ppm and 3.5 ppm peak for -HOCH2CH2CH2-. Four different mol ratio of HTNR with IPDI was carried out to find the best formulation with good properties as propellant. Flory-Rehner equation depict that only slightly increasing occur with higher IPDI mol ratio but mixing with Ammonium Perchlorate (AP) and Aluminium Powder (AL) significantly improve the crosslink density. Melting point for HTNR is near to room temperature and it increase abruptly after crosslink with IPDI up to range of 148-150 °C. For all formulation, cross section morphology showed occurrence of porosity and brittle type of failure however HTNR has good contact with AL and AP. 2 : 1 molar ratio depict the best burning rate but the combustion characteristic shows less energy and spark compared to HTPB binder.

Crystallization under Stress and Non-Gaussian Behavior of Macromolecular Networks

1966 ◽  
Vol 39 (3) ◽  
pp. 685-711 ◽  
Author(s):  
K. J. Smith ◽  
A. Greene ◽  
A. Ciferri
Keyword(s):  
Natural Rubber ◽  
Substantial Reduction ◽  
Large Error ◽  
Chemical Degradation ◽  
Present System ◽  
Approximate Theory ◽  
Energy Component ◽  
Constant Length ◽  
Amorphous Content ◽  
Non Gaussian

Abstract (a) Shape of the isotherm.—The appearance of a “first” upturn in the conventional isotherm is associated with non-gaussian behavior. Crystallization takes place, under usual conditions, in a range of elongation where non-gaussian behavior prevails and tends, initially, to reduce the stress below the value expected for the amorphous non-gaussian network. On further stretching a “second”, steeper up turn may be observed which is associated with a substantial reduction of amorphous content and, therefore, with crystallization. This interpretation, which is coherent with most of the experimental observations (particularly the lack of correspondence between the first upturn and the downturn of the energy component, the swelling behavior and the independence of the first upturn upon the mode of obtaining the isotherm and upon temperature) is satisfactorly fitted in the present picture of behavior of the network under stress. (b) Energy component.—Extensive measurements and theoretical analysis indicate that the ratio fe/f is essentially unaffected by swelling with n-hexadecane and by elongation, even in the elongation range following the gaussian region. The best value, i.e., 0.18, which is affected bya large error (± 0.05) confirms that the unperturbed dimensions of natural rubber molecules increase with temperature, an effect for which molecular description is lacking. Values of fe/f≦0.10, as they may occur for stretched natural rubber networks, are indicative of crystallization. (c) Crystallization under stress.—The following differences between experiments and Flory's approximate theory were noticed: (1) the value of ΔH is about one half the value to be expected on the basis of independent measurements. This indicates that the experimental variation of Tm with α is steeper than predicted; 2) Tm at α=1 appears to be some 30° below the actual isotropic melting temperature; 3) most serious differences between theory and experiments are found in the smooth change of slope of τ vs T curves at constant length in the region immediately following Tm. The part played in these effects by failure to obtain true equilibrium may not be essential judging from the fact that the best attempt made to reach equilibrium conditions did not reveal significant effects. Improved attempts to obtain equilibrium for the present system and using the present experimental technique are precluded by the occurrence of chemical degradation. Further experiments, on different polymer systems focusing attention on the region of incipient crystallization (or, preferably, “final melting”), are suggested.

COMPARISON OF THREE DIFFERENT DEGRADATION METHODS TO PRODUCE LIQUID EPOXIDIZED NATURAL RUBBER

2016 ◽  
Vol 89 (1) ◽  
pp. 177-198 ◽  
Author(s):  
Pejvak Rooshenass ◽  
Rosiyah Yahya ◽  
Seng Neon Gan
Keyword(s):  
Natural Rubber ◽  
Uv Irradiation ◽  
Chemical Degradation ◽  
Epoxidized Natural Rubber ◽  
Coupling Reactions ◽  
Uv Degradation ◽  
Roll Mill ◽  
Potential Applications ◽  
Potassium Peroxodisulfate ◽  
Chain Lengths

ABSTRACT Epoxidized natural rubber (ENR) has a high molecular weight, which has limited its solubility and processibility. For many potential applications, such as adhesives and coatings, ENR needs to be degraded into shorter chain lengths to form liquid ENR (LENR). We compared three different methods of preparing LENR: mechanical milling, chemical degradation initiated by potassium peroxodisulfate, and photooxidation initiated by ultraviolet (UV) irradiation. All the methods break down the ENR via free radicals but at different rates and by different mechanisms. In the LENR produced by these methods, ketone, aldehyde, carboxylic acid, and ester and lactone groups were observed; however, a hydrofuranic structure was only formed with UV degradation. The oxirane group was not affected significantly during the degradation, indicating that the chain sessions occurred predominantly via the –C=C– bonds. Spectroscopic analyses revealed that the consumption of a double bond is related to the extent of degradation initiated by potassium peroxodisulfate and UV irradiation. Mastication with a two roll mill produced LENR with a greater degree of unsaturation and fewer polar groups; therefore, presumably, significant chain scissions occurred from the rupturing of –C–C– single bonds. Comparing the reaction time, more LENR was obtained by UV degradation. As expected, an increase in the oxygen concentration led to the generation of more radicals, which could result in some coupling reactions.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

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