Processing Characteristics of Synthetic Rubbers and Their Use in the Manufacture of Extruded Products

1944 ◽  
Vol 17 (4) ◽  
pp. 932-940 ◽  
Author(s):  
A. E. Juve
Keyword(s):  
Natural Rubber ◽  
Present Situation ◽  
General Purpose ◽  
High Dispersion ◽  
High Recovery ◽  
Vulcanized Rubber ◽  
Roll Mill ◽  
The Difference ◽  
Extruded Products ◽  
Internal Mixer

Abstract The difference in processing behavior between synthetic rubbers and natural rubber becomes evident when production facilities designed for processing natural rubber are used for synthetic rubbers. All the synthetic rubbers in one respect or another are harder to process than natural rubber. Under circumstances other than the present emergency, processing equipment suitable for handling the synthetic rubbers would gradually be evolved. In the present situation, synthetic rubbers must be processed with equipment already available. In this discussion natural rubber and the general purpose synthetic rubbers, GR-S, GR-M and GR-I, will be considered. The processing of dry rubber consists essentially of the incorporation of vulcanizing agents, pigments, oils, and other ingredients by a process of kneading, followed by the forming of the mix by extrusion or calendering into shapes suitable for fabrication preparatory to final cure. The mixing step, which is accomplished on a two-roll mill or in an internal mixer, requires that the rubber be within a plasticity range that will permit satisfactory dispersion of the ingredients. If the plasticity is too low the rubber tends to crumble, and if it is too high dispersion is poor. Crude natural rubber is quite tough, and before breakdown has some of the properties of vulcanized rubber, such as high recovery after moderate distortion. In the crude state it is extremely difficult to obtain satisfactory dispersion of pigments. It is therefore necessary to soften it by mastication or other means so that the pigments are more readily incorporated and power requirements are lowered. In addition, its nerve or tendency to recover after distortion is greatly reduced. Synthetic rubbers, in general, differ from natural rubber in their susceptibility to softening by mastication, and they show different relationships between nerve and plasticity than does natural rubber.

The Effect of Thermal Aging on Mechanical Properties and Morphological Properties of Thermoplastic Vulcanizates Based on Natural Rubber and Polystyrene

2020 ◽  
Vol 990 ◽  
pp. 262-266
Author(s):  
Prathumrat Nu-Yang ◽  
Atiwat Wiriya-Amornchai ◽  
Jaehoon Yoon ◽  
Chainat Saechau ◽  
Poom Rattanamusik
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Natural Rubber ◽  
Thermal Aging ◽  
Morphological Properties ◽  
Vulcanized Rubber ◽  
Thermoplastic Vulcanizates ◽  
Internal Mixer ◽  
Processing Properties

Thermoplastic vulcanizates or TPVs is a type of materials exhibiting excellent properties between thermoplastic and elastomer by combining the characteristics of vulcanized rubber with the processing properties of thermoplastics. This research aims to study the effect of thermal aging on the morphology and mechanical properties of thermoplastic vulcanizates (TPVs) based on a mixture of natural rubber (NR) and polystyrene (PS). TPVs samples were prepared using the internal mixer at a mass ratio of NR/PS 70/30, 50/50, 30/70 and 0/100. Tensile properties and impact strength showed that when the amount of NR increased tends of impact strength and elongation at break increased but tends of tensile strength decreased. On the other hand, tends of tensile strength for thermal aging at 70°C for 3 days increased when the amount of PS increase. The blending ratio of NR / PS at 70/30 is the best. It gave a worthy increase from 19.94 MPa to be 25.56 MPa (28.18%).

Effects of Filler Incorporation Routes on Mechanical Properties of Low Density Polyethylene/Natural Rubber/Silica (LDPE/NR/Si) Composites

2014 ◽  
Vol 679 ◽  
pp. 154-157 ◽  
Author(s):  
Pei Ying Teoh ◽  
Abdulbaset Mohamed Erfeida ◽  
Xuan Viet Cao ◽  
Du Ngoc Uy Lan
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Low Density Polyethylene ◽  
Tensile Fracture ◽  
Low Density ◽  
Tensile Fracture Surface ◽  
Roll Mill ◽  
Typical Morphology ◽  
Internal Mixer

Low density polyethylene (LDPE) and natural rubber (NR) filled silica composites were prepared by using internal mixer (Brabender) at 150°C and 50 rpm for 10 minutes. Silica was incorporated into polymer matrix by three mixing routes by using Brabender. In mixing I, filler was added into LDPE/NR blend. In mixing II, filler was added prior to LDPE, which was further compounded with NR. In mixing III, filled was pre-dispersed into NR using two-roll mill, after that the compound is blended with LDPE. The effects of filler incorporation routes on the morphological and tensile properties of prepared composites were studied. Observation from SEM result showed that silica tended to localize in NR phase than LDPE phase in the composite. In addition, silica filled LDPE/NR composite exhibited the highest tensile strength in mixing II and lowest in mixing III. Tensile fracture surface of the composites showed typical morphology of LDPE and NR phase depending on mixing methods. KEYWORDS: LDPE/NR, silica, mixing order, tensile properties, morphology

Bisalkylation Theory of Neoprene Vulcanization

1955 ◽  
Vol 28 (4) ◽  
pp. 1021-1031 ◽  
Author(s):  
Peter Kovacic
Keyword(s):  
Zinc Oxide ◽  
Natural Rubber ◽  
Organic Compounds ◽  
Chlorine Atom ◽  
Structural Difference ◽  
General Purpose ◽  
Active Chlorine ◽  
Functional Difference ◽  
Methyl Group ◽  
The Difference

Abstract Among the organic compounds that are recommended for use with magnesia and zinc oxide as vulcanizing agents for Neoprene are ethylenethiourea (2-imidazolidinethione), p,p′-diaminodiphenylmethane and the di-o-tolylguanidine salt of dicatechol borate. In the absence of sulfur, these agents in combination with zinc oxide do not vulcanize natural rubber. This points up a marked difference in the way these elastomers vulcanize. Although a major structural difference is the chlorine atom in Neoprene in place of the side methyl group in natural rubber, the small amount of tertiary allylic chlorine formed by 1,2-polymerization is the important functional difference. The labile chlorine amounts to about 1.5 per cent of the total chlorine in a general-purpose Neoprene made at 40° C, such as Neoprene Type W used in this work. In Neoprene latex, this active chlorine is gradually liberated, and the polymer becomes cross-linked. This paper demonstrates the importance of the labile chlorine in the vulcanization of dry Neoprene, accounts for the difference in the vulcanization of Neoprene and natural rubber, and suggests a bisalkylation theory of Neoprene vulcanization.

Study on Natural Rubber Quality of Micro-Cut Tapping with Gas-Stimulation

2013 ◽  
Vol 834-836 ◽  
pp. 175-179
Author(s):  
Kai Dian Wang ◽  
Mao Fang Huang ◽  
Chun Liang Yang ◽  
Zong Qiang Zeng ◽  
Zhi Xiong Liang ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Natural Rubber ◽  
Protein Content ◽  
Dynamic Property ◽  
Control Group ◽  
Vulcanized Rubber ◽  
The Difference

The natural rubber samples produced by conventional tapping methods were used as a control, then analyzed the dry rubber property of natural rubber, the dynamic property and Physical & mechanical property of vulcanized rubber using Rubber processing analyzer and Thermogravimetric Analyze the difference between the properties of dry rubber and vulcanized rubber produced by Micro-cut Tapping with Gas-stimulation. The results indicated that the tensile strength, tear strength elastic modulus of dry rubber that produced by Micro-cut Tapping with Gas-stimulation are respectively 20%, 7% lower than the control. The protein content of dry rubber materials produced by Micro-cut Tapping with Gas-stimulation is 16.7% higher than control group.

Influence of Agitation Equipment on Reinforcing Effect and Dispersion State of Cellulose Nano-Fibers in Natural Rubber

2017 ◽  
Vol 754 ◽  
pp. 23-26
Author(s):  
Sho Omori ◽  
Takayuki Morita ◽  
Koki Matsumoto ◽  
Asahiro Nagatani ◽  
Tatsuya Tanaka
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Reinforcing Effect ◽  
X Ray ◽  
Centrifugal Mixer ◽  
Vulcanized Rubber ◽  
Biomass Resource ◽  
Dispersion State ◽  
Biomass Resources ◽  
Internal Mixer

There are many rubber products like tires, and reinforcing agents derived from fossil resources such as carbon black (CB) are used for them. However, in recent years, conversion to biomass resources has been demanded due to problems such as depletion of fossil resources. Therefore, we have studied the composite of natural rubber (NR) reinforced with cellulose nano-fibers (CNF), which has attracted attention as a next-generation biomass resource. It is very difficult to uniformly disperse CNF in the conventional kneading process. Therefore, it is preferable to agitate CNF in NR latex. Then, it is necessary to study the optimum agitation equipment of CNF. In this study, the reinforcing effect by CNF was investigated when the agitation equipment was changed. Agitation of NR latex and CNF was carried out by a hand, a homogenizer, a dispersion mixer, and planetary centrifugal mixer. Thereafter, agitated materials were dried and masterbatches were made. Furthermore, the masterbatch and vulcanizing agents were kneaded using an internal mixer. Tensile test and X-ray CT observation of the prepared vulcanized rubber sheets were carried out to evaluate the reinforcing effect and dispersion state of CNF. As a result, the planetary centrifugal mixer was most useful to uniformly disperse CNF.

Aging of Natural Rubber Vulcanizates in the Presence of Dithiocarbamates

1959 ◽  
Vol 32 (3) ◽  
pp. 739-747 ◽  
Author(s):  
J. R. Dunn ◽  
J. Scanlan
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Protective Action ◽  
Dicumyl Peroxide ◽  
Vulcanized Rubber ◽  
Aging Properties ◽  
Photochemical Aging ◽  
Natural Rubber Vulcanizates

Abstract The thermal and photochemical aging of extracted dicumyl peroxide-, TMTD (sulfurless)- and santocure-vulcanized rubber, in presence of a number of metal and alkylammonium dithiocarbamates, has been investigated by measurements of stress relaxation. The dithiocarbamates have a considerable protective action upon the degradation of peroxide- and TMTD-vulcanizates, but they accelerate stress decay in santocure-accelerated vulcanizates. The reasons for this behavior are discussed. It is suggested that the excellent aging properties of unextracted TMTD vulcanizates are due to the presence of zinc dimethyldithiocarbamate formed during vulcanization.

scholarly journals Thermal Behavior ofTacca leontopetaloidesStarch-Based Biopolymer

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Nurul Shuhada Mohd Makhtar ◽  
Miradatul Najwa Muhd Rodhi ◽  
Mohibah Musa ◽  
Ku Halim Ku Hamid
Keyword(s):  
High Temperature ◽  
Natural Rubber ◽  
Thermal Behavior ◽  
Thermal Performance ◽  
Palm Oil ◽  
Palm Olein ◽  
Low Cost ◽  
Thermal Testing ◽  
Crude Palm Oil ◽  
Roll Mill

Starch is used whenever there is a need for natural elastic properties combined with low cost of production. However, the hydrophilic properties in structural starch will decrease the thermal performance of formulated starch polymer. Therefore, the effect of glycerol, palm olein, and crude palm oil (CPO), as plasticizers, on the thermal behavior ofTacca leontopetaloidesstarch incorporated with natural rubber in biopolymer production was investigated in this paper. Four different formulations were performed and represented by TPE1, TPE2, TPE3, and TPE4. The compositions were produced by using two-roll mill compounding. The sheets obtained were cut into small sizes prior to thermal testing. The addition of glycerol shows higher enthalpy of diffusion in which made the material easily can be degraded, leaving to an amount of 6.6% of residue. Blending of CPO with starch (TPE3) had a higher thermal resistance towards high temperature up to 310°C and the thermal behavior of TPE2 only gave a moderate performance compared with other TPEs.

Adhesion of Vulcanized Rubber Surfaces: Characterization of Unmodified and Electron Beam Modified EPDM Surfaces and Their Co-vulcanization with Natural Rubber

2009 ◽  
Vol 23 (13-14) ◽  
pp. 1763-1786 ◽  
Author(s):  
Ganesh C. Basak ◽  
Abhijit Bandyopadhyay ◽  
Y. K. Bharadwaj ◽  
S. Sabharwal ◽  
Anil K. Bhowmick
Keyword(s):  
Electron Beam ◽  
Natural Rubber ◽  
Vulcanized Rubber

EFFECT OF DEVULCANIZATION ON CROSSLINK DENSITY AND CROSSLINK DISTRIBUTION OF CARBON BLACK FILLED NATURAL RUBBER VULCANIZATES

2016 ◽  
Vol 89 (4) ◽  
pp. 653-670 ◽  
Author(s):  
Anu Mary Joseph ◽  
Benny George ◽  
Madhusoodanan K. N. ◽  
Rosamma Alex
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Morphological Properties ◽  
Original Sample ◽  
Ambient Conditions ◽  
Absolute Value ◽  
Roll Mill ◽  
Percentage Retention ◽  
The Absolute

ABSTRACTCarbon black filled natural rubber (NR) vulcanizates were devulcanized at ambient temperature in a two roll mill. The effect of cure system, that is, conventional vulcanization (CV), semiefficient vulcanization (semi EV), and efficient vulcanization (EV) systems, used for vulcanization of the original sample, on the efficiency of devulcanization was studied. The efficiency of devulcanization expressed as percentage devulcanization of the samples calculated from residual crosslink density measurements was correlated with the sol fraction of the devulcanized samples based on Horikx analysis. Using chemical probe analysis, we determined (i) the crosslink distribution pattern of the original sample, (ii) the extent to which the different types of crosslinks—that is, polysulfidic, disulfidic, and monosulfidic crosslinks—have been debonded or broken during the shearing process in the two roll mill, and (iii) the pattern of bond formation during revulcanization. Mechanical shearing predominantly breaks the majority crosslink type (polysulfidic crosslinks in CV and semi EV cure systems and disulfidic crosslinks in EV samples). Irrespective of the significant reduction in total crosslink density in all three sets of samples, chain shortening reactions similar to the post-crosslinking chemical reactions at curing temperatures also occur during mechanical shear at ambient conditions, which increased the absolute value of monosulfidic links in CV and semi EV systems. However, in the devulcanized EV system, the absolute value of polysulfidic crosslinks increased, which might be due to the re-crosslinking of the cleaved bonds. All the devulcanized samples were revulcanized, and the mechanical and morphological properties were analyzed. The percentage retention of the vulcanizate properties after revulcanization of the devulcanized samples correlated very well with efficiency of devulcanization.

Thermal Properties and Crystallisation Behaviour of Thermoplastic Natural Rubber (TPNR) Nanocomposites

2013 ◽  
Vol 812 ◽  
pp. 125-130 ◽  
Author(s):  
Siti Norasmah Surip ◽  
Z.Y. Zhang ◽  
H.N. Dhakal ◽  
N.N. Bonnia ◽  
S. H. Ahmad
Keyword(s):  
Thermal Properties ◽  
Natural Rubber ◽  
Nucleating Agent ◽  
Preparation Technique ◽  
Preparation Methods ◽  
Blending Method ◽  
Liquid Natural Rubber ◽  
Tan Δ ◽  
Thermoplastic Natural Rubber ◽  
Internal Mixer

The effect of preparation technique on the crystallisation behavior and thermal properties of TPNR filled nanoclay nanocomposites was investigated. The nanocomposites were prepared via melt blending method using internal mixer (Haake 600P). Two types of nanocomposites preparation technique were employed which is method A and B. In method A, the nanoclay was pre-mixed with liquid natural rubber (LNR) before it was charged into the other materials. For method B, the nanoclay was directly charged into the molten TPNR matrix. The result shows, preparation methods were significantly affect the crystallinity and thermal properties of TPNR nanocomposites. DSC thermogram revealed that nanocomposites crystallinity was increased when prepared by method A but decreased with method B. An increment in polypropylene crystallinity was attributed by the nanoclay which is believed to be as a nucleating agent. DMA thermogram suggested that the preparation method has affected the storage modulus and tan δ but not the glass transition temperature (tg).

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