Tetramethylthiuram Disulphide Research Articles

The Effect of Adding Pine Tar Oil and Petrosin as Tackifier Ingredients on The Quality of Liquid Rubber Compound-based Adhesives

This research is focused on the development of adhesives through the utilization of different types of tackifiers. The primary raw materials employed comprise 60% concentrated latex, which is subsequently blended with additives that have been dispersed, including KOH as a stabilizing agent, stearic acid and ZnO as activators, BHT as an antioxidant, CaCO3 as a filler, MBTS (Mercaptobenzothiazole disulfide) and TMTD (Tetramethyl Thiuram Disulphide) as accelerators, and sulfur as a vulcanizing agent. This research explored two specific variations of tackifiers: pine tar oil and petrosin. The characterization of the adhesives encompasses an analysis of acidity (pH), viscosity, adhesive strength, functional group analysis using FTIR, thermal properties, and XRD. The research findings showed that the optimal conditions were achieved in the third variation of the adhesive, with the same ratio of pine tar oil tackifier and petrosin of 4 grams each. In this particular variation, adhesives conforming to the SNI 12- 7195-2006 standards were produced, displaying an adhesion strength of 1.506 N/mm, a viscosity of 1075 cP, and a pH level of 4.6. Furthermore, thermal testing results reveal that the adhesive created with tackifier (V3) exhibits thermal resistance up to 350°C, a glass transition temperature of 354°C, and a melting point of 378°C.

Kinetic and structural details of urease inactivation by thiuram disulphides

This paper reports on the molecular details of the reactivity of urease, a nickel-dependent enzyme that catalyses the last step of organic nitrogen mineralization, with thiuram disulphides, a class of molecules known to inactivate the enzyme with high efficacy but for which the mechanism of action had not been yet established. IC50 values of tetramethylthiuram disulphide (TMTD or Thiram) and tetraethylthiuram disulphide (TETD or Disulfiram) in the low micromolar range were determined for plant and bacterial ureases. The X-ray crystal structure of Sporosarcina pasteurii urease inactivated by Thiram, determined at 1.68 Å resolution, revealed the presence of a covalent modification of the catalytically essential cysteine residue. This is located on the flexible flap that modulates the size of the active site channel and cavity. Formation of a Cys-S-S-C(S)-N(CH3)2 functionality responsible for enzyme inactivation was observed. Quantum-mechanical calculations carried out to rationalise the large reactivity of the active site cysteine support the view that a conserved histidine residue, adjacent to the cysteine in the active site flap, modulates the charge and electron density along the thiol SH bond by shifting electrons towards the sulphur atom and rendering the thiol proton more reactive. We speculate that this proton could be transferred to the nickel-coordinated urea amide group to yield a molecule of ammonia from the generated Curea-NH3+ functionality during catalysis.

Development of high melt strength polypropylene and its application in thermoplastic elastomeric composition

High melt strength polypropylene (HMS-PP) with a long-chain branched structure is a modified form of polypropylene (PP) which has basic properties of regular PP but with superior melt drawability. This paper reports on the development of gel-free HMS-PP from a linear isotactic PP through the introduction of long-chain branching on its backbone via a reactive extrusion process, using dicetyl-peroxydicarbonate (PODIC) alone or in combination with a coagent. The melt strength and the mechanical properties such as impact and flexural strength of PP showed improvements with the modification with PODIC. 5000 ppm by weight of PODIC was found to provide the best balance of properties. The efficacies of zinc diethyldithiocarbamate (ZDC) and tetramethyl thiuram disulphide (TMTD) as coagents in combination with PODIC to augment properties of HMS-PP further were explored. TMTD offered slightly enhanced performance benefits as compared to ZDC at an optimized concentration of 100 ppm by weight. The application potential of HMS-PP in thermoplastic elastomeric blends of HMS-PP with ethylene-propylene-diene monomer (EPDM) rubber at a fixed ratio of 35/65 by weight was also investigated. Structure-property correlations were established between the extent of long-chain branching in the modified PP and the properties of the resultant thermoplastic elastomeric composition.

Off-line TLC-IR (UATR) characterization of additives in EPDM rubber

Abstract Sulfur donor accelerators and vulcanization agents, such as peroxides, due to their chemical characteristics and good thermal stability properties in rubber formulations, are essential to provide solutions in different sectors, such as aerospace and automotive, since they reduce the polymer degradation process (reversal), which can influence the performance of the elastomeric material. In this way, the use of methodologies for the components knowledge of a formulation is imperative for the structure proper establishment/property relationship of the elastomeric artifacts. The development of methodology that can separate and characterize the rubber formulation components is a constant challenge, still allows gaps, and is usually done by conventional but not coupled instrumental techniques. In this scenario, this paper aimed to contribute to the use of the off-line coupling of thin-layer or thin-layer chromatography (TLC)/infrared spectroscopy (FT-IR), by universal attenuated total reflection (UATR) for N-cyclohexyl-2-benzothiazolesulfenamide (CBS), tetramethyl thiuram disulphide (TMTD) and dicumyl peroxide (DCP), in formulations of ethylene and propylene diene monomer (EPDM) rubber containing the plasticizer naphthenic oil. This plasticizer was characterized in formulations that presented higher content of this compound, but the eluting systems were not effective in separating DCP. However, better separation of CBS and TMTD was observed.

Management of wilt and root rots of chickpea (Cicer arietinum) using Trichoderma harzianum in India

Wilt (Fusarium oxysporum f. sp. ciceris), dry root rot (Rhizoctonia bataticola) and collar rot (Sclerotium rolfsii) are the major soil-borne diseases of chickpea (Cicer arietinum) prevalent across the country and causing substantial yield losses. Field experiments were conducted at eight different hot spot locations of these diseases belonging to six states namely, New Delhi (Delhi), Indore, Sehore and Jabalpur (Madhya Pradesh), Badnapur (Maharashtra), Junagadh (Gujarat), Samba (Jammu and Kashmir) and Durgapura (Rajasthan) to evaluate and validate the performance of Pusa 5SD (a novel seed dressing formulation developed from Trichoderma harzianum) alone and in combination with fungicide along with recommended fungicidal seed treatment against wilt and root rots of chickpea under AICRP Chickpea during 2010 to 2013 crop seasons. Seed treatment with Pusa 5SD (T. harzianum) alone and in combination with Vitavax power (carboxin + thiram) proved to be effective for the management of wilt and root rots at different locations. A combination of seed treatment with Pusa 5SD and Vitavax power (carboxin + thiram) provided the lowest disease incidence (12.2%) along with the highest grain yield (1053.3 kg/ha). Cardendazim (Bavistin) + Tetra methyl thiuram disulphide (thiram) and Vitavax power also reduced the diseases incidence (13.0%) and enhanced the grain yield (998.2 kg/ha) of chickpea. The bio-formulation Pusa 5SD showed effectiveness across the locations and varieties against wilt, dry root rot and collar rot of chickpea.

Optimisation of accelerators and vulcanising systems on thermal stability of natural rubber/recycled ethylene–propylene–diene-monomer blends

The present paper concerns the thermal stability of natural rubber/recycled ethylene–propylene–diene-monomer (NR/R-EPDM) blends. The blends were prepared using various accelerators and vulcanising systems. Four types of accelerators were selected, i.e., N-tert-butyl-2-benzothiazyl-sulphonamide (TBBS), N-cyclohexyl-benzothiazyl-sulphenamide (CBS), tetramethylthiuram disulphide (TMTD) and 2-mercaptobenzothiazol (MBT). Subsequently, semi-efficient vulcanisation (semi-EV), efficient vulcanisation (EV), peroxide and mixed sulphur/peroxide vulcanising systems (semi-EV/Peroxide and EV/Peroxide) were observed in the latter study. Two methods of thermal analysis namely, thermo-oxidative ageing and thermogravimetric analysis were conducted. The results indicated that TMTD and MBT-vulcanised blends showed slightly higher thermal stability than that of CBS and TBBS vulcanised blends however, CBS-vulcanised blends exhibited satisfactory overall mechanical and thermal stability in comparison to the other accelerators used. In the case of optimisation of vulcanising systems, semi-EV showed the highest un-aged tensile strength when compared against semi-EV/Peroxide, EV, EV/Peroxide and peroxide vulcanising systems, respectively. However, EV, EV/Peroxide and peroxide vulcanising systems provided slightly higher thermal stability, due to the blends consisted of more stable monosulphidic and carbon–carbon linkages in the vulcanised network. The activation energies of degradation of the blends were determined by applying the Coats–Redfern’s method. It can be verified that the activation energies observed in the blends were in good agreement with the thermogram results.

Thermoplastic Elastomers Based on Natural Rubber/Polypropylene Blends: Effect of Blend Ratios and Dynamic Vulcanization on Rheological, Thermal, Mechanical, and Morphological Properties

Thermoplastic elastomers (TPEs) based on natural rubber (NR)/polypropylene (PP) with different blend ratios were prepared and studied. The TPEs were obtained by dynamic vulcanization of NR/PP using a sulfur (S)/N-tert-butyl-2-benzothiazolesulphenamide (TBBS) and tetramethylthiuram disulphide (TMTD) curative system during processing in the melt state in an internal mixer equipped with cam rotors. Rheological, thermal, mechanical, dynamic, and morphological properties of the TPEs prepared were investigated. Based on this study a mechanism for the NR crosslinking was proposed where the sulfur vulcanization occurs through radical substitution in the forms of polysulfide bridges. The dynamic vulcanization process increases the stiffness of the NR phase in the TPEs and modifies the rheological and thermal behavior of the system compared to the behavior of the basic material PP. The crosslinked NR particles restrict the spherulitic growth and the regular arrangement of the spherulites of PP phase, decreasing the crystallinity degree. On the other hand, a reduction of mobility of the chain segments was also observed and, consequently, an increase of the Tg values. NR/PP TPEs with high content of NR showed superior mechanical performance compared to the uncrosslinked NR/PP blends in terms of tensile strength, Young's modulus and hardness. An increase of approximately 320% in Young's modulus values was obtained for the NR70/PP30 TPE compared to NR70/PP30. Morphological studies revealed the formation of large aggregates of NR domains in NR/PP TPEs which increased in size with an increase of the rubber content.

Raw rubber properties of crepe rubber manufactured from preserved natural rubber latex using different combinations of preservatives

Objective of this study was to investigate the effect of different preservative systems used in the concentrated latex manufacturing industry on physical properties of the latex crepe made out of them. Unfractionated and unbleached (UFUB) crepe rubber manufactured from latices preserved with ammonia, tetramethylthiuram disulphide, zinc oxide and a 1:1 mixture of tetramethylthiuram disulphide (TMTD) and zinc oxide (LATZ) were subjected to examine their raw rubber properties. It was observed that UFUB crepe rubber manufactured out of either ammonia preserved, ZnO preserved or chemically untreated latices have better resistance to thermo-oxidative degradation compared to UFUB crepe rubber made out of both TMTD and LATZ preserved latex. Further, it was observed that neither ammonia nor ZnO has any effect on the thermal degradation of crepes made out of ammonia or ZnO preserved latex. It was clear from the results that the TMTD added as a component of the preservative system adversely affects the resistance to thermo-oxidative degradation as judged by PRI of crepe produced. Crepe rubber manufactured from TMTD preserved latex exhibits unusually lower PRI and a nitrogen content comparable with the normal UFUB crepe rubber. Skim crepe rubber which is considered a by-product of the latex centrifuging industry, usually records higher nitrogen percentages and lower PRI values. Therefore, evaluation of these two parameters could be used to differentiate skim crepe rubber from normal UFUB crepe rubber. It was also observed that TMTD has a strong negative impact on PRI of crepe rubber even at very low concentrations. It could be proposed that dimethylthiuram monosulphide (DMTMS) free radicals generated by thermal decomposition of TMTD are responsible for this PRI reduction.

Deprotonative metalation of aromatic compounds using mixed lithium–iron combinations

The deprotonation of 2-methoxypyridine was attempted using putative (TMP)3FeLi prepared from different iron sources. Using iodine to intercept the metalated 2-methoxypyridine, the best result was obtained from FeBr2 (1equiv) using THF at room temperature; nevertheless, in addition to the expected iodide, the corresponding 2,2′-dimer was obtained (86% total yield). The origin of the competitive formation of the 2,2′-dimer was not identified but mechanisms were suggested to explain its formation. It was observed that the nature of the electrophile employed to trap the 3-metalated 2-methoxypyridine has a strong impact on this dimer formation, the latter being favored using iodine (35% yield), but also benzophenone (28%), benzoyl chloride (22%), methyl iodide (27%), allyl bromide (15%), benzyl bromide (41%), and tetramethylthiuram disulphide (36%); for this reason, the yields of the expected derivatives were only 51, 15, 62, 0, <5, 18, and 0%, respectively. In contrast, using aldehydes readily led to the expected pyridine alcohols without dimerization (59% yield using 3,4,5-trimethoxybenzaldehyde and 66% yield using pivalaldehyde). 2,6-Dimethoxypyridine (in 68% yield), anisole (47%), 2,4-dimethoxypyrimidine (50% at C5 and 3% at C6), 2-fluoropyridine (64%), and thiophene (49%) were similarly converted into the corresponding alcohols after subsequent trapping with pivalaldehyde. Using iodine to trap the 2-metalated anisole did not lead to dimer formation, and 2-iodoanisole was isolated in 71% yield.

The Study on the Time Dependency and the Stability of Cobalt Sulphide Nanoparticles Under an Electron Beam

We report on the synthesis and characterization of cobalt sulphide (CoS(1.097)) nanoparticles using a cobalt tetramethylthiuram disulphide complex as a single-source precursor. To study the effect of reaction time on the optical and morphological properties of the synthesized nanoparticles, aliquots from the reaction mixture were collected after different intervals of time. The absorption spectra were time dependent, with the 5 min aliquot being the most blue-shifted from bulk and the subsequent samples showing a slight shift towards the bulk. Photoluminescence of the nanoparticles showed a single emission wavelength of 341 nm, however, the peak intensity of nanoparticles decreased with reaction time. The morphology of the synthesized nanoparticles was investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution TEM (HR-TEM). Results from the SEM images showed the formation of spherical CoS(1.097) nanoparticles and the size of the observed nanoparticles increase with increasing reaction time. However, the TEM results showed a change in the morphology of the particles from spherical to wire-like. The change in morphology was thought to be induced by the high voltage electron beam and this was supported by the HR-TEM and optical results.

Bioagent based integrated management of Phytophthora blight of pigeonpea

Phytophthora blight (Phytophthora drechsleri f. sp. cajani) is one of the major yield limiting factors of short duration varieties of pigeonpea (Cajanus cajan). For eco-friendly and sustainable management of the disease, four antagonists, Pseudomonas fluorescens, Bacillus subtilis, Trichoderma viride and T. hamatum, were evaluated under in vitro and in vivo conditions. P. fluorescens produced maximum inhibition zone, while Trichoderma species overgrew on the host mycelium and caused lysis. The fungicides apron (metalaxyl), ridomil MZ (metalaxyl + mancozeb), capton (captaf), difolatan (captafol), thiram (tetramethylthiuram disulphide) and bavistin (carbendazim) at both 0.3 and 0.6% were found to be compatible with P. fluorescens while B. subtilis was compatible only with apron at 0.3%. T. viride grew and sporulated well at 0.3 and 0.6% apron and 0.2% ridomil MZ. The bioagents proved to have potential and those which were compatible under in vitro were evaluated under field conditions. The efficacy of fungicide in combination with bioagents was greater compared to fungicide alone. The integration of P. fluorescens with apron or ridomil MZ as seed treatment significantly reduced the Phytophthora blight incidence and enhanced seed germination and grain yield.

New binary systems containing TMTD-amidino phenyl thiourea and CBS-amidinophenyl thiourea for the vulcanization and rheological behavior of natural rubber latex

The use of accelerators in rubber latex is basically different from their use in dry rubber. In the present study, N amidino N'phenyl thiourea (APT) which is more nucleophilic than thiourea was studied as a secondary accelerator along with tetra methyl thiuram disulphide (TMTD) and N-cyclohexylbenzothiazyl sulphenamide (CBS) in the vulcanization of natural rubber latex. These binary systems were found to be very effective in reducing the vulcanization time. The optimum dosages for this non-toxic secondary accelerator required were derived. Rheological studies of the compounded latex show that the introduction of APT in these systems does not have adverse effect in processing in comparison with the thiourea systems. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 2310-2316, 2010

The Effect of Accelerators on Curing Characteristics and Properties of Natural Rubber/Chlorosulphonated Polyethylene Rubber Blend

The aim of this work was to determine the influence of accelerator type on curing behavior and properties of sulphur vulcanized rubber blend based on natural rubber (NR) and chlorosulphonated polyethylene (CSM). In NR/CSM compounds filled with carbon black three types of accelerator were used: N-cyclohexylbenzothiazylsulphenamide (CBS), tetramethylthiuram disulphide (TMTD), and 2-mercaptobenzothiazol (MBT). The curing characteristics were estimated using oscillating disk rheometer. The results revealed that the accelerator type not only affects the cure characteristics, but also has great influence on the mechanical properties of obtained elastomers. It was determined that the tensile strength of rubber blends cured in the presence of TMTD was relatively high.

The Effect of Precursor Concentration, Temperature and Capping Group on the Morphology of CdS Nanoparticles

A novel ligand to the synthesis of nanoparticles has been employed in this study. A Tetramethylthiuram disulphide cadmium complex (abundant in sulphur atoms) was used as a single-source precursor for the synthesis of CdS nanoparticles. The CdS nanoparticles were synthesized under various conditions and were characterized using UV/Vis, PL, XRD and TEM. The influence of the precursor concentration, temperature and capping environment as factors affecting the morphology and size of the nanoparticles was investigated. We observed that with an increase in precursor concentration, there was an increase in particle sizes and the morphology evolved from spherical to rod-shaped nanoparticles. An increase in temperature showed only evidence of increasing the particle sizes whilst the capping environment had a profound influence on the morphology of the nanoparticles. The work reported in this paper demonstrate that factors such as temperature, concentration and the capping group affects the growth of nanoparticles either in size and/or shape.

Study of the crosslink density, dynamo-mechanical behaviour and microstructure of hot and cold SBR vulcanizates

Vulcanizates of hot and cold styrene-butadiene rubber (SBR) were prepared with five different cure systems based on sulphur, 2-mercaptobenzothiazole disulphide (MBTS) and tetramethylthiuram disulphide (TMTD). The degree of crosslinking was investigated by swelling in benzene and stress-strain analysis. Thiol-amine chemical probes were employed to determine the type of crosslinks in the sulphur vulcanizates, and their dynamic-mechanical properties and thermal stability were studied in both the raw (non-crosslinked) and crosslinked state. The butadiene microstructure and the total unsaturation were determined by Raman spectroscopy. The influence of the crosslink density and the type of crosslink formed on the measured properties is discussed.

In Situ Dynamic Vulcanization of Poly(Vinyl Chloride)/Acrylonitrile-butadiene Rubber Blends

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 formation was verified through the formation of C─ S bonds in the blends.

Avaliação de bis(4-metilfenilditiocarbimato)zincato(II) de tetrabutilamônio como acelerador em composições de borracha natural

Neste trabalho a substância ZNIBU [bis(4-metilfenilditiocarbimato)zincato(II) de tetrabutilamônio] foi usada em formulações de borracha natural (NR) e o seu efeito como acelerador de vulcanização foi investigado. As composições, vulcanizadas com a substância em questão, foram submetidas a testes mecânicos e os resultados comparados com os de outras composições vulcanizadas com os aceleradores comerciais CBS (N-ciclohexil-2-benzotiazol-2-sulfenamida), TMTD (dissulfeto de tetrametiltiuram) e MBTS (dissulfeto de benzotiazol). Propriedades como dureza, resiliência e densidade foram avaliadas em presença ou não da carga negro de fumo.

Blendas PVC/NBR por processamento reativo I: desenvolvimento do processo de vulcanização Dinâmica in situ

Vulcanização dinâmica é o processo de vulcanização de um elastômero durante a mistura no estado fundido com um termoplástico, que resulta em uma classe de materiais denominada termoplásticos vulcanizados. Neste trabalho, um novo tipo de termoplástico vulcanizado foi obtido por vulcanização dinâmica in situ da blenda PVC/NBR, utilizando-se um sistema de cura a base de enxofre (S) e combinação dos aceleradores 2,2-ditiomercaptobenzotiazol (MBTS) e dissulfeto de tetrametiltiuram (TMTD). As blendas PVC/NBR (90/10, 80/20 e 70/30% em massa) foram processadas em um reômetro de torque Haake (Rheomix 600) a 160 °C com rotação de 60 rpm. As blendas obtidas por processamento reativo foram caracterizadas por calorimetria diferencial de varredura (DSC) para determinação do grau de cura. Observou-se aumento no grau de cura das blendas com o tempo de mistura sendo o sistema de cura considerado eficiente.

The Effect of Thiuram on the Uptake of Lead and Copper by Melissa officinalis

In this work the effects of thiuram on the uptake of lead and copper by lemon balm (Melissa officinalis) were examined. Thiuram (tetramethylthiuram disulphide) is used as a fungicide to protect seeds, fruit, vegetables, ornamentals, turf crops, and herbs from a variety of fungal diseases. The preliminary investigation involved soil analyses (content of organic substances, acidity, total lead and copper, exchangeable and bioavailable forms, and mechanical analysis). The analysis showed that the soil used for the study was not contaminated with lead or copper. In this work the amounts of lead and copper were determined in roots and above-ground parts of: (a) plants untreated with thiuram; (b) plants which were sprayed with thiuram (3 mg per pot). It was found that thiuram influences the amount of lead and copper accumulated in the plant. The treatment of the plants with thiuram caused an increase of the content of lead in the roots (65, 75 days with fungicide) and reduction of lead in the above-ground parts. The addition of the fungicide caused a drop in the content of Cu in the roots, while the content of Cu in the above-ground parts decreased slightly (65, 75 days with fungicide).

Cross‐reactivity between thiurams

Retesting with an allergen at a site with previous allergic contact dermatitis has been shown to enhance reactivity. It has been suggested that retesting with a cross-reactive allergen will also induce hyperreactivity. Concurrent sensitization to more than 1 thiuram is common, but whether this is due to concomitant primary sensitization or cross-reactivity is uncertain. The aim of this study was to investigate the use of retesting to distinguish between concomitant sensitization and cross-reactivity in the rubber chemicals tetraethylthiuram disulphide (TETD) and tetramethylthiuram disulphide (TMTD). There was a non-significant trend towards enhanced reactivity for both TETD and TMTD when testing in an area with previous allergic contact dermatitis due to TETD. Cross-reactivity between the 2 chemicals is likely, but a definite conclusion from this pilot study is not possible.