Cable Compound Research Articles

Delta Tecnic reportedly guarantees efficient insulation in the cable industry and impeccable spark test results

On September 28, Delta Tecnic reports that the masterbatch manufacturer reduces the granule size tenfold to achieve better dilution of the masterbatch in the cable compound; 25% of the company's sales are in the automotive industry, where satisfactory spark test results are reportedly more difficult to achieve.

Synthesis of stabilizers based on glycerides of monocarboxylic acids for industrial chloroparaffins

Objectives. The study aimed to develop new effective heat stabilizers based on glycerol esters of monocarboxylic acids for industrial chlorinated paraffins and to select of the optimal ratio of active ingredients in the stabilizing composition in order to provide the maximum thermostabilizing effect.Methods. The thermostabilizing effect of the studied samples on chlorinated paraffins was evaluated according to the standard method for determining the thermal stability of liquid chlorinated paraffins in terms of the mass fraction of split off hydrogen chloride. Quantitative and qualitative analysis of the obtained mixtures of monocarboxylic acid glycerides was carried out using chromato-mass spectrometry.Results. Glycerides of monocarboxylic acids (oleic, octanoic, hexanoic, and propionic acids) were obtained and identified, and the compositions of the resulting mixtures of mono-, di- and triesters were determined. The stabilizing effect of the obtained mixtures of glycerides of monocarboxylic acids in the amount of 0.5–2.0 wt parts per 100 wt parts of unstabilized industrial chlorinated paraffin CP-30 was determined. The combined use of glycerides of monocarboxylic acids with calcium-containing compounds as a complex stabilizer with a molar ratio of esters/Ca 0.93–0.86/0.07–0.14, respectively, was investigated. Chloroparaffin CP-470, stabilized by the developed complex stabilizer, was successfully used in a polyvinyl chloride composition for cable compound of the brand OM-40.Conclusions. A proposed variant of a complex stabilizer for chlorinated paraffins based on Russian raw materials for import substitution will expand the range of effective stabilizers for organochlorine substances. Glycerides of monocarboxylic acids are shown to exhibit a thermostabilizing effect on industrial chlorinated paraffins. The relationship between the length of the hydrocarbon substituent of the carboxylic acid in the ester and the thermostabilizing effect is obtained. With an increase in the number of carbon atoms in the hydrocarbon substituent of the carboxylic acid, the heat-stabilizing ability decreases. The minimum sufficient concentration of glycerides of carboxylic acids was 0.05 ± 0.005 mol/kg, above which no increase in the thermostabilizing effect on chloroparaffin was observed. A synergistic ratio of the components of the stabilizing mixture in terms of thermal stability—glycerides of monocarboxylic acids/calcium-containing compounds—was found equal to 0.85–0.9/0.15–0.1.

Effect of MgO•Sb<sub>2</sub>O<sub>5 </sub>on Fire Resistance and Physical and Mechanical Properties of Cable PVC-Plasticate

Based on magnesium carbonate and antimony oxide (V), MgO•Sb2O5 was obtained. In the formulation of fire-resistant cable PVC-plasticate, antimony (III) oxide was replaced by MgO•Sb2O5 and the fire resistance and physical and mechanical properties of the resulting compound were investigated. It is shown that the replacement of antimony (III) oxide in the composition of PVC cable compound MgO•Sb2O5 leads to the production of a compound that is not inferior in its characteristics to the original plastic compound. In particular, the fire resistance of cable PVC-plasticate, standard industrial formulation and with the obtained MgO•Sb2O5, is practically the same (OI=32%). It has been established that the physical and mechanical characteristics of the cable compound, when replacing antimony oxide (III) with MgO•Sb2O5 in the formulation, remain at the level of the original compound, while MgO×Sb2O5 will have a less negative impact on the environment.

Influence of a mixture of calcium and zinc stearates on the thermal and mechanical properties of PVC plastic

A complex stabilizer based on a mixture of calcium and zinc stearates was developed, which was used to replace the tribasic lead sulphate in the formulation of cable polyvinyl chloride plasticate. The influence of a complex stabilizer on the basic physical and mechanical properties of cable polyvinyl chloride plasticate is investigated. It was found that the use of a complex stabilizer in the formulation of cable polyvinyl chloride plasticate does not lead to a decrease in the thermal, technological and operational characteristics of the material. It is shown that the thermal properties of the cable compound containing a complex stabilizer remains at the level of the original plastic. This is due to the ability of the complex stabilizer to effectively bind hydrogen chloride released during the destruction of the polymer matrix. It is established that the cable polyvinyl chloride plasticate containing in the formulation of a complex stabilizer in its mechanical characteristics is not inferior to the industrial compound, and in some respects surpasses it.

On the possibility of upgrading the composition of cable PVC compound

Upgrade of the composition of cable PVC-compound grade I40-13A with aluminum hydroxide has been carried out. Fire resistance, thermophysical and physical-mechanical properties of the obtained compounds have been investigated. It is shown that the modernization of the composition of cable PVC compound with aluminum hydroxide enables production of a fi re-resistant compound. It was found that aluminum hydroxide significantly changes the thermophysical properties of cable plastic compound. In particular, heat generation and smoke generation during plastic compound combustion are significantly reduced. It has been established that the physical-mechanical and rheological characteristics of the cable compound modernized with aluminum hydroxide remain at the level of the original compound. The optimal amount of aluminum hydroxide for the modernization of cable plastic compound of the I40-13A grade is 10–15 wt.%.

Study of the Effect of Organoclay on the Structure of Cable PVC Compound

The effect of the organoclay content in polyvinyl chloride plasticate on the features of the supramolecular structure and properties of the layered silicate nanocomposite was studied. X-ray diffraction studies showed that with an increase in the number of layered silicate nanofiller, the nanocomposite structure goes from intercalated to exfoliate. Using a combination of scanning and atomic force electron microscopy methods, it has been shown that when organomodified montmorillonite is introduced into polyvinyl chloride plastic compound, montmorillonite nanoparticles act as crystallization nuclei and along with the preservation of “old” supramolecular structures in the melt, “new” supramolecular formations appear. When studying the dependence of tensile strength of nanocomposite polyvinyl chloride on the content of nanofiller, it was found that the maximum strength of the nanocomposite is achieved at a 5-7 % organoclay concentration.

Irradiation Tests of Optical Fibers and Cables Devoted to Corium Monitoring in Case of a Severe Accident in a Nuclear Power Plant

The DIstributed Sensing for COrium Monitoring and Safety (DISCOMS) project considers the use of optical fiber sensing cables embedded into the concrete floor under the reactor vessel for remote monitoring of a severe nuclear accident. This article focuses on the selection and testing of single-mode optical fibers with limited radiation-induced attenuation (RIA). To simulate the normal operation period of the reactor, followed by a severe accident, several gamma and mixed (neutron–gamma) irradiations were performed, thanks to the Atomic Energy Commission (CEA) Saclay facilities, POSEIDON irradiator and ISIS reactor, up to a gamma cumulative dose of about 2 MGy and fast neutrons fluence ( ${E} \,\, >1$ MeV) of $6\times 10^{15}$ n/cm2. In comparison with the first gamma test on standalone fibers, a significant increase of the RIA at 1550 nm appeared during the second test on fibers encapsulated in sensing cables. Molecular hydrogen generated by the cable compound radiolysis induced an increase of the hydroxyl (OH) attenuation broad spectral peak centered at 1380 nm. The radiation-induced OH growth mechanism is confirmed by the comparison of the extended absorption spectral responses of the standalone and encapsulated fibers. A third gamma irradiation run permitted to measure the radiolytic hydrogen production yield of some compounds of a dedicated temperature cable sample. The efficiency of a carbon-coating layer over the silica cladding, acting as a barrier against hydrogen diffusion into the optical fiber core, was successfully tested under gamma irradiation as well as in a final test under neutron irradiation.

Studies in Effect of Nano Aluminium Trihydroxide Concentration on Flame Retardant Properties of Ethylene Propylene Diene Rubber

The science and technology of synthetic polymers has undergone explosive growth in the last few decades and the number of different polymeric materials in our built environment increases almost daily. All organic polymers burn and thus entail some measure of fire hazard in some situations. With increasing awareness of the nation’s fire problem it has become evident that the problems associated with flammability of polymeric materials must be attacked and solved. With the large number of polymers in commercial use. Problems of flammability and fire retardation are complex and multifaceted properties have to be developed, or existing polymers must be modified by addition of fire-retardant compounds. EPDM Rubber has many attractive properties such as low shrinkage, ease of cure and processing, excellent moisture, solvent and chemical resistance, good mechanical and electrical properties, as well as ease of modification to optimize the properties. However flammability is a major limitation in area requiring high flame resistance. Aluminum trihydroxide (ATH) due to its flame retardancy property is widely used as non reinforcing filler in wires and cable compound along with silica and carbon black. In this study carbon black is fully replaced by nano ATH to make environment friendly rubber products. However, the dispersion of nano particles in rubber is remarkably poor and hence techniques like melt mixing, solution mixing and master batching of nano ATH with EVA (Ethylene- vinyl acetate) are used to improve the dispersion of nano ATH particles in EPDM elastomers. In the current study we have used melt mixing for improving the dispersion of nano ATH and excellent results were obtained with optimum loading of nano ATH.

The chemistry of interfacial tracking

Interfacial tracking occurs in a wide range of high voltage apparatus and frequently leads to electrical breakdown. A review of the chemistry of interfacial tracking along interfaces consisting of crosslinked polyethylene (XLPE), ethylene-propylene rubber (EPR) cable compound, and silicone rubber (SR) termination compound is given. Interfacial tracking experiments were conducted on the interfaces commonly encountered in cable accessories, including XLPE/EPR, XLPE/SR, EPR/EPR, and EPR/SR. The tracking products were analyzed using FTIR and GCMS. XLPE and EPR showed carbonization and an increase in cyclic and smaller chain hydrocarbons produced from radicals originating from hydrogen abstraction and chain scission. Oxidation of XLPE was observed with evidence of a Norrish type II photochemical reaction. SR showed evidence of SiO2 production along with lower molecular weight silicones. Tracking across an interface containing SR resulted in erosion of the SR side of the interface.

Wastes from woodworking industry as a filler for a cable sheathing compound

The suitability of an alternative filler for a cable polyvinyl chloride plastic compound was studied. Physicomechanical, chemical, and relaxation properties and inflammability of plastic compound were analyzed in relation to the filler content.

Filler blend of carbon nanotubes and organoclays with improved char as a new flame retardant system for polymers and cable applications

Multi wall carbon nanotubes (MWCNTs) or single wall carbon nanotubes (SWCNTs) were used as fillers in polyethylene (PE). Only MWCNTs reduced the heat release rates caused by polymer degradation. MWCNTs can be more effective in heat release reduction than organoclays. The char generated by the filler blend 'MWCNTs and organoclays' as a synergistic flame retardant system in an ethylene vinylacetate (EVA) based polymer blend was improved compared with the char generated by the only organoclay based nanocomposite. Initial results indicated that there was a strengthening effect of the char by MWCNTs. The synergistic improvement for heat release reduction by a blend of the two fillers 'MWCNTs and organoclays' was used for the development of a flame retardant cable compound. 1.5 kg of MWCNTs was compounded on a Buss ko-kneader to generate 60 kg of a nanocomposite based on the filler blend. The flame retardant properties of insulated wires made either by the filler blend or by 'classical' organoclays were measured.

Effects of tin additives on the flammability and smoke emission characteristics of halogen-free ethylene-vinyl acetate copolymer

Zinc hydroxystannate (ZHS) is found to be an effective partial replacement for the conventional hydrated fire-retardant fillers alumina trihydrate (ATH) and magnesium hydroxide (MH) when incorporated into a halogen-free EVA cable compound. In contrast to earlier findings for halogen-containing polymers, ZHS-coated versions of the fillers are somewhat less effective than equivalent composition mixtures of ZHS+filler. Incorporation of ZHS also greatly enhances the performance of an ATH/nano-clay synergistic fire-retardant system in the EVA formulation and allows marked reductions to be made in overall filler level with no or little compromise in terms of flame-retardant and smoke-suppressant properties.

Influence of blend composition on the physical, flame retardancy, dielectric, aging, and solvent resistance properties of poly[ethylene(vinyl acetate)] and polychloroprene

Poly[ethylene(vinyl acetate)] (EVAc) has been blended with polychloroprene (CR) to develop a compound for application in the cable industry. Physical, flame retardancy, dielectric, and solvent resistance properties have been investigated for the blends. On air and brine aging, the tensile properties for 50/50 blend remains almost unchanged, though retention in tensile properties is maximum for CR in solvent aging and for EVAc in air aging. 50/50 blend shows substantially lower set and hardness compared to EVAc. The limiting oxygen index of 50/50 blend is found to be higher compared to EVAc, which indicates sufficient inflammable capability of 50/50 blend in atmospheric air. A substantially lower dielectric constant, conductivity with good physical properties, and inflammability of 50/50 blend suggests its suitability for use as a cable sheathing compound.

Stabilization of peroxide crosslinked polyethylene

In peroxide crosslinked low density polyethylene for wire and cable applications there is a critical balance between the additives. Normally dicumyl peroxide is applied as the crosslinking agent and stabilizers are needed towards thermo-oxidative degradation as described by existing specifications. In addition, the phenomenon known as premature crosslinking, referred to as “scorch”, demands that a certain amount of a phenolic stabilizer deactivates radicals formed during the extrusion step. The aim of this study was to correlate the structure of different phenolic compounds to their capability to react with radicals formed during the extrusion, which would give information in design of new compounds for which scorch properties are of importance. This work shows that the less hindered the phenol is, the more it can contribute to the improvement of the scorch behavior. On the other hand, a good stabilizing effect can only be achieved with hindered phenols together with a secondary stabilizer. Since there is a limit to the absolute amount of additives in LDPE also the molar weight of the additives as well as the number of active groups are crucial for the overall performance of the cable compound. The balance between the different additives to achieve a technically reliable solution is discussed.

Stabilization of peroxide crosslinked polyethylene

In peroxide crosslinked low density polyethylene for wire and cable applications there is a critical balance between the additives. Normally dicumyl peroxide is applied as the crosslinking agent and stabilizers are needed towards thermo-oxidative degradation as described by existing specifications. In addition, the phenomenon known as premature crosslinking, referred to as scorch, demands that a certain amount of a phenolic stabilizer deactivates radicals formed during the extrusion step. The aim of this study was to correlate the structure of different phenolic compounds to their capability to react with radicals formed during the extrusion, which would give information in design of new compounds for which scorch properties are of importance. This work shows that the less hindered the phenol is, the more it can contribute to the improvement of the scorch behavior. On the other hand, a good stabilizing effect can only be achieved with hindered phenols together with a secondary stabilizer. Since there is a limit to the absolute amount of additives in LDPE also the molar weight of the additives as well as the number of active groups are crucial for the overall performance of the cable compound. The balance between the different additives to achieve a technically reliable solution is discussed.

US5472658 Increasing modulus of heat-treated fibre

Zinc hydroxystannate (ZHS) is found to be an effective partial replacement for the conventional hydrated fire-retardant fillers alumina trihydrate (ATH) and magnesium hydroxide (MH) when incorporated into a halogen-free EVA cable compound. In contrast to earlier findings for halogen-containing polymers, ZHS-coated versions of the fillers are somewhat less effective than equivalent composition mixtures of ZHS+filler. Incorporation of ZHS also greatly enhances the performance of an ATH/nano-clay synergistic fire-retardant system in the EVA formulation and allows marked reductions to be made in overall filler level with no or little compromise in terms of flame-retardant and smoke-suppressant properties.

Corrosive effects of smoke on metal surfaces

Corrosion of metal surfaces is usually associated purely with acid gases. It is well known, however, that all structural elements (even noncombustible ones) present in a fire are heavily corroded by it, whatever the materials involved in the fire. This project investigated corrosion from burning materials releasing acid, alkaline and neutral smoke, even without thermal damage. Carbon steel coupons, with various pre- and post-treatments, and copper mirrors, were exposed to 30 g/m 3 of smoke in a static chamber at high humidity for 1 h, close to ambient temperature and at c. 100°C. Metal samples were held 28 days before analysis. The materials used for generating smoke were: a generic PVC wire and cable compound, a low HCl emission PVC wire and cable compound, a halogen-free polyethylene wire and cable compound, wool, wood, polystyrene, neoprene, nylon and none (control). All copper mirrors exhibited almost infinite resistance after exposure. Nitrogen-containing materials caused the severest copper corrosion, by dissolving more copper than the other smokes. All steel coupons were corroded. The amount of weight loss dependent on treatment and type of smoke. Corrosion was minimised by cleaning the combustion debris soon after exposure. The corrosion of untreated steel coupons exposed at different temperatures showed that the extent of condensation plays a crucial role. Acid gas concentration correlated with corrosion only if condensation onto the target was artificially enhanced, by placing the target at a lower temperature than the surrounding surfaces. This work has shown: 1. (a) Smoke is corrosive, even in the absence of acid gases. 2. (b) Target treatment, before and after exposure, critically affects the level of corrosion. 3. (c) Smoke corrosivity testing should involve corrosion of actual targets.

Treeing in mechanically strained h.v.-cable polymers using conducting polymer electrodes

An improved laboratory technique for the measurement of tree initiation voltages in polymeric insulation is described, which allows a closer approach to the conditions in extruded cable insulation. The potential importance of using divergent-field electrodes fabricated from polymeric cable screen compound is demonstrated by a reversal of the order of merit of two polymers when screen compound and aluminium are used as electrodes. Reductions in tree initiation voltage of up to 40% have been created by bending the test specimens to achieve mechanical strain levels, believed to be in the range 5–8%. The percentage reduction in tree initiation voltage appears to correlate with mechanical stress rather than strain, showing the importance of the modulus of the polymer. Any problems due to strain at the flexible-insulation/electrode boundary of this new test specimen arrangement are likely to be relevant to practical cables.

Diffusion in ethylene polymers. II. Desorption of water

AbstractThe kinetics of desorption for water from various ethylene polymers have been studied by weight loss. In either branched (DYNK) or linear (Marlex 50) polymers the solubility of water was too low to be measured by our techniques (< 0.05 mg. H2O/g. polymer). This result is not in agreement with values reported by earlier workers (0.2–0.9 mg. H2O/g. polymer). When DYNK is oxidized, however, measurable quantities are absorbed. We find 0.11 mg. H2O/g. polymer for DYNK containing about 0.6% oxygen by weight. In this case the desorption data provide a measure of the diffusion coefficient, D ≃ 10−7 cm.2/sec. Similar results are found for a cable compound containing about 5% butyl rubber and 0.07% antioxidant introduced into DYNK by milling.