Crosslinking in blends of nitrile rubbers and poly(vinyl chloride)
TL;DR: In this paper, the ETU/S curative system produces crosslinking effects which in some respects are comparable with, and in some other respects are even substantially better than, those produced by the conventional TMTD/S system, particularly with respect to consequential curing parameters and blend vulcanizate properties including morphological patterns and ageing behaviour.
About: This article is published in Polymer.The article was published on 1992-01-01. It has received 8 citations till now. The article focuses on the topics: Nitrile rubber & Vinyl chloride.
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TL;DR: In this paper, a vulcanized thermoplastic was obtained by in situ dynamic vulcanization of polyvinyl chloride (PVC)/acrylonitrile-butadiene rubber (NBR) blends using a sulphur/ tetramethylthiuram disulphide (TMTD) and mercaptobenzothiazyl disulo-disulphides (MBTS) curative system during processing at the melt state.
Abstract: Poly(vinyl chloride) (PVC)/acrylonitrile-butadiene rubber (NBR) blends can be obtained through a dynamic vulcanization process as a melt-processible thermoplastic elastomer which produces parts that look, feel and perform like vulcanized rubber with the advantage of being processible as a thermoplastic material. In this study, a vulcanized thermoplastic was obtained by in situ dynamic vulcanization of PVC/NBR blends using a sulphur/ tetramethylthiuram disulphide (TMTD) and mercaptobenzothiazyl disulphide (MBTS) curative system during processing at the melt state. The blends were melt-mixed using a Haake Rheomix 600. The curing behavior of NBR was then investigated by a Monsanto rheometer. The thermal analyses were performed and the cross-linking at different mixing times was calculated using DSC. FT-IR was also performed for characterization of the blends. The cross-link densities of the samples were measured by a swelling method. The degree of cure increases with the mixing time. The cross-linking format...
9 citations
Cites methods from "Crosslinking in blends of nitrile r..."
...Ghosh et al.[15] reported that cross-linking of NBR and PVC can be accomplished individually in a PVC/NBR blend by using an ethylenethiourea (ETU) /sulfur curing system....
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TL;DR: In this paper, the effect of TOA on the mechanical properties was investigated by exposing the PVC/NBR TPEs in an air oven at 100°C for 3, 7, 14, and 21 days.
Abstract: Plasticized poly(vinyl chloride)/nitrile butadiene rubber (PVC/NBR) thermoplastic elastomers (TPEs) were dynamically vulcanized in the melt stage with the incorporation of a semi-efficient vulcanizing system using a Brabender Plasticorder at 150°C and 50 rpm rotor speed. Curative concentration was progressively increased from 0 to 1 part per hundred (phr) NBR in order to study the effect of dynamic curing on the plasticized blend. The mechanical properties investigated include tensile strength, elongation at break (%EB), modulus at 100% elongation (M100), tear strength, and hardness. The effect of thermo-oxidative ageing (TOA) on the mechanical properties was investigated by exposing the PVC/NBR TPEs in an air oven at 100°C for 3, 7, 14, and 21 days. It was found that tensile and tear strength passed through a maximum value, whereas, hardness and M100 increased steadily with the sulfur content and ageing time. On the contrary, the elongation at break reduced gradually with ageing time until it re...
8 citations
TL;DR: In this paper, a new kind of thermoplastic vulcanizates was obtained by in situ dynamic curing of polyvinyl chloride (PVC)/nitrile rubber (NBR) blends.
Abstract: Dynamic vulcanization is a process of vulcanization of an elastomer during melt mixing with a thermoplastic wich results in material called thermoplastic vulcanizates or TPVs. In this study, a new kind of TPV was obtained by in situ dynamic curing of poly(vinyl chloride) (PVC)/nitrile rubber (NBR) blends. The crosslinking of PVC/NBR blends was accomplished using sulphur (S)/tetramethylthiuram disulphide (TMTD) and mercaptobenzthiazyl disulphide (MBTS) curative system during the reactive processing. The blends of PVC/NBR at the ratio of 90/10; 80/20 and 70/30 wt. (%) were melt mixed using a Haake Rheomix 600 at 160 °C and rotor speed of 60 rpm. The curing behavior of NBR was investigated by a Monsanto Rheometer and the degree of cure was calculated using differential scanning calorimetry (DSC) for different mixing times. It was observed that the degree of cure increases with the mixing time and the crosslinking system used in this work was considered efficient.
7 citations
TL;DR: In this paper, the effect of thermo-oxidative aging on the mechanical properties was investigated by exposing the PVC-ENR TPEs in an air oven at 80°C for 168 h.
Abstract: Plasticised poly(vinyl chloride)–epoxidised natural rubber (PVC–ENR) thermoplastic elastomers (TPEs) were prepared by melt mixing in a Brabender Plasticorder at 150°C and a rotor speed of 50 rev min-1. Curative concen tration was progressively increased from 0 to 1 phr in order to study the effect of dynamic curing on the plasticised blend. The mechanical properties investigated include tensile strength, elongation at break, modulus at 100%; elongation, tear strength, hardness, and compression set. The effect of thermo- oxidative aging on the mechanical properties was investigated by exposing the PVC–ENR TPEs in an air oven at 80°C for 168 h. It was found that all physical and mechanical properties increased continuously with increasing sulphur concentration. A steady reduction in swelling index with increasing concentration of curatives is excellent evidence for a significant increase in crosslink density. The thermo-oxidative aging process resulted in a significant enhancement in mechanical prop...
6 citations
Journal Article•
TL;DR: In this article, a Brabender plastic-order torque rheometer was used for dynamic vulcanisation of polyvinyl chloride and epoxidised natural rubber in the presence of a plasticiser.
Abstract: Thermoplastic elastomers have been prepared by blending poly(vinyl chloride) and epoxidised natural rubber in the presence of a plasticiser. The blends were melt mixed using a Brabender plasticorder torque rheometer. To effect dynamic vulcanisation, varying concentrations of a semi-efficient sulphur curative system were added during the mixing stage. The effectiveness of dynamic vulcanisation was studied using Brabender plastograms, a moving dic rheometer, swelling index measurement, and Fourier transform infrared spectroscopy. The values of torque obtained from both rheometers increased with an increase in curative concentration, while the swelling index decreased. The difference absorbance spectra from the Fourier transform infrared spectroscopy indicated sulphur crosslink formation. Processibility studies of the dynamically vulcanised thermoplastic elastomers showed that they have good processing stability and are processible as thermoplastics.
6 citations
References
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01 Jan 1985
TL;DR: In this paper, the authors describe a chain transfer characterisation of polymers charge-transfer complexes, charge transfer complexes and charge transfer complexes of charge transfer and charge-Transfer complexes.
Abstract: Cellular Materials Cellulose Cellulose, Biosynthesis Cellulose, Graft Copolymers Cellulose, Microcrystalline Cellulose Derivatives Cellulose Esters, Inorganic Cellulose Esters, Organic Cellulose Ethers Cement Additives Chain-Reaction Polymerization Chain Transfer Characterization of Polymers Charge-Transfer Complexes Chelate- Forming Polymers Chemical Analysis Chemically Resistant Polymers Chitin Chloroprene Polymers Chlorotrifluorethylene Polymers Chromatography Classification of Polymerization Reactions Coating Methods Coatings Coatings, Electrodeposition Cold Forming.
7,256 citations
TL;DR: In this article, the authors studied the performance of polyvinyl chloride (PVC) with 2-R-4,6-dithiol-s-triazine (R-DT) and metal activators and found that the activation energy was about 16.6-33 kcal/mol over the temperature range 160-195°C.
Abstract: Crosslinking of poly(vinyl chloride) (PVC) with 2-R-4,6-dithiol-s-triazine (R-DT) and metal activators has been studied to determine crosslinking rate constants, induction periods, and apparent activation energy and the final efficiency of crosslinking agents. The rate constants were about 1.4–7.5 min−1 and the induction periods were about 6.8–24.3 min for various kinds of R-DT at 180°C. The activation energy was about 16.6–33 kcal/mol over the temperature range 160–195°C.
The rate constants were strongly influenced by 2-substituted groups (R) in R-DT and increased in the order R′O-≪ R′NH-< (R′)2N, where R′ is an alkyl or aryl group. Further, the rate constants increased in the order of: metal carboxylates < metal carboxylates < metal oxides for the activators and in the order of: Pb < Mg < Ca < Ba < Na for metal atoms.
The final efficiency was about 75–80% for the activators such as MgO, MgCO3, PbO, and SnO. The activators containing Na, Ca, and Ba atoms, however, gave final efficiency of more than 100%.
8 citations
TL;DR: In this article, a novel PVC-crosslinking reaction with 2-R-4,6-dithiol-s-triazine (I) has been presented to obtain insoluble products which hardly color on ageing.
Abstract: The effects of crosslinking on PVC are well known in regard to the improvement of mechanical properties, creep behavior, and softening temperature. Little is known, however, on the application of the PVC-crosslinking reaction, because most of crosslinked PVC tends to color easily at elevated temperatures. In this paper, a novel PVC-crosslinking reaction with 2-R-4,6-dithiol-s-triazine (I) has been presented to obtain insoluble products which hardly color on ageing. The reaction rate and induction period of the crosslinking reaction with I are made controllable by selecting the basicity of the substituent R of I as well as that of an acid acceptor in the blends. The utility of I as stabilizer as well as a crosslinking agent is also emphasized.
8 citations
5 citations
TL;DR: In this article, the initial rate constants of dehydrochlorination at 40°C induced by ammonium hydroxide or n-butylamine in cyclohexanone solution were studied by following the disappearance of NH 4 OH or n.BA on reacting with the HCl liberated.
5 citations