Structure Of PVC Research Articles

Electromigration Effects in Overcurrent PVC-Insulated Copper Wire: Failure and Deformation Impacts

Electromigration is a critical issue in materials science and electrical engineering, significantly impacting the reliability and efficiency of electrical systems. This study investigates the electromigration behavior of PVC-insulated copper wires under various overcurrent conditions, focusing on material degradation and electrical performance. Copper cables, identified as 046620.3 Eterna CU/PVC 1.5 mm2, were subjected to currents ranging from 0 to 110 A. The mean time to failure (MTTF) was calculated using Black’s equation, revealing a sharp decline in MTTF with increasing current density. Surface morphology analysis using SEM showed the formation of voids and hillocks at higher currents, indicating severe electromigration damage. XRF analysis demonstrated significant changes in the elemental composition, particularly a reduction in copper content and an increase in chlorine and other elements, suggesting degradation of the PVC insulation. FTIR spectroscopy revealed substantial chemical changes in the PVC material, especially under extreme overcurrent conditions, highlighting dehydrochlorination and carbonyl group formation. There is a clear relationship between overcurrent conditions and electromigration phenomena, as evidenced by the observed damage to surface morphology, changes in elemental composition, and alterations in the chemical structure of PVC. The mechanisms and causes of electromigration are explained comprehensively in this work, illustrating how increased overcurrent accelerates the electromigration process, leading to the formation of voids and hillocks in the copper conductor. This damage is accompanied by a significant reduction in copper content and an increase in chlorine levels, indicating the degradation of PVC insulation. FTIR spectra further confirmed these findings by showing chemical changes such as dehydrochlorination and carbonyl group formation under high current stress. The MTTF values reflect the severity of these impacts, with samples exposed to higher currents showing drastically reduced lifespans. For instance, samples subjected to 100 A and 110 A currents exhibited MTTF values of 0.2 minutes and 0.004 minutes, respectively.

Improving the flame retardancy and smoke suppression of flexible PVC by incorporating zinc borate‐modified diantimony trioxide

AbstractThe properties and structure of flexible PVC by incorporating zinc borate (ZB)‐modified diantimony trioxide (Sb2O3) were investigated. The results of flame retardancy and smoke suppression testing indicate that there was an obvious maximum Limited oxygen index (LOI) value of PVC/20 wt.% ZB–Sb2O3 composites reached 37.5% and passed the UL 94 V‐0 rating. An obvious synergistic effect between ZB and Sb2O3 was observed by LOI, SDR, and TG. Moreover, remarkable decreases in the smoke density were observed when ZB–Sb2O3 was incorporated into PVC. In addition, the tensile strength and elongation at break of PVC/ZB–Sb2O3 composites was higher than PVC/Sb2O3 composites, and this ameliorative effect was mainly arising from the ZB–Sb2O3 nanoparticles, which reduced the degree of fatal defects on PVC. The addition of ZB and Sb2O3 greatly increased the amount of residual char and apparently improved the mechanical properties of PVC composites. According to scanning electron microscopy photographs of residual char, after thermal decomposition, there were many fragments linked to the condensed phase and the compact char layer. Fourier transform infrared spectroscopy shows the residues char was composed of benzene ring, the flame retardants occurred and the condensed phase with significant interactions.

Sublethal effects induced by different plastic nano-sized particles in Daphnia magna at environmentally relevant concentrations

A growing number of studies have reported the toxic effects of nanoplastics (NPs) on organisms. However, the focus of these studies has almost exclusively been on the use of polystyrene (PS) nanospheres. Herein, we aim to evaluate the sublethal effects on Daphnia magna juveniles of three different NP polymers: PS-NPs with an average size of 200 nm, polyethylene [PE] NPs and polyvinyl chloride [PVC] NPs with a size distribution between 50 and 350 nm and a comparable mean size. For each polymer, five environmentally relevant concentrations were tested (from 2.5 to 250 μg/L) for an exposure time of 48 h. NP effects were assessed at the biochemical level by investigating the amount of reactive oxygen species (ROS) and the activity of the antioxidant enzyme catalase (CAT) and at the behavioral level by evaluating the swimming behavior (distance moved). Our results highlight that exposure to PVC-NPs can have sublethal effects on Daphnia magna at the biochemical and behavioral levels. The potential role of particle size on the measured effects cannot be excluded as PVC and PE showed a wider size range distribution than PS, with particles displaying sizes from 50 to 350 nm. However, we infer that the chemical structure of PVC, which differs from that of PE of the same range size, concurs to explain the observed effects. Consequently, as PS seems not to be the most hazardous polymer, we suggest that the use of data on PS toxicity alone can lead to an underestimation of NP hazards.

Mechanisms of formation of polyene structures in radiation-functionalized PVC-MWCNT polymer nanocomposites

Quantum-chemical modeling of the geometry of PVC molecules and the calculation of Raman scattering spectra were performed. The calculated spectra are in good agreement with the experimental ones, including the extraction of adjacent Cl atoms. The Raman spectra of PVC-MWCNT nanocomposites with various filler content with functionalization during electron irradiation with an absorption dose of 1 Mrad were obtained. It was shown that with the change of MWCNT content in irradiated samples there is a complex rearrangement of the molecular structure of PVC and conjugate sequences due to the influence of nanotubes and irradiation, as well as to the aggregation of MWCNT.

The Promoting Effect of Multifunctional Groups on the Thermal and Mechanical Properties of PVC Materials

The development of PVC materials grafted with mannich base originated from myrcene (P-MAM-g, where the mannich base derived from myrcene is abbreviated as MAM) via green and effective synthetic methods is a good strategy to avoid unacceptable discoloration and deterioration of thermal and mechanical properties caused by autocatalytic dehydrochlorination (DHC) during PVC processing. In this study, MAM with double bonds, amino groups, ester groups, and phospholipid groups was introduced into the chains of PVC to improve the thermal stability of PVC. The experimental results showed that the covalent attachment of MAM to PVC enhanced both the initial and the long-term stability of PVC. The enhanced performance of P-MAM-g compared with unmodified PVC is attributed to the simultaneous introduction of double bonds and amino groups into the PVC structure. The double bonds trapped the unstable chlorine atoms originated from the degradation of the PVC chain and reacted with the labile macromolecular radicals originated from PVC, thus inhibiting the radical degradation of the PVC chain. Furthermore, the amino groups absorbed the HCl produced in the degradation of PVC, inhibiting the adverse effects of HCl. P-MAM-g displayed better intrinsic flexibility and anti-migration ability of organic functional components compared with the control PVC materials. A possible stabilizing mechanism of the P-MAM-g was also presented.

Modification of poly(vinyl chloride) by mefenamic acid in presence of micro metallic oxides as self photostabilizer

To date, many approaches have been made to stabilize the chemical structure of PVC when exposed to sunlight in outdoor usage. This work includes utilizing mefenamic acid (1 % per polymer weight) as a new photo stabilizer unit to adjust PVC to enhance resistance to change under UV exposure. Modification by attaching a new unit that contains an aromatic substance could protect the polymer from UV light due to its ability to absorb it. Positive results were obtained, as the interaction between mefenamic acid and PVC succeeded, using the FTIR technique to characterize the chemical structure of the product. FTIR spectrum of modified PVC shows the disappearance of (OH) band in the region above 3200 cm−1 which is clear evidence that the connection between the polymer and mefenamic acid has happened through the OH group. In addition, we have investigated the influence of microparticle metallic oxides such as TiO2, and Cr2O3, using only 1 % per modified polymer weight, on the photodegradation process of PVC materials. Several approaches have been utilized to investigate the photo-stability of studied materials which are FTIR functional group indices, weight-loss percentage, microscopic images, SEM, and AFM. They demonstrated that modified PVC gives better stability after exposure to UV in comparison to unmodified PVC. It's interesting to note that adding titanium dioxide to modified PVC has increased the amount of UV protection by acting as a UV shielding agent and blocking the light's path to the polymer. Thus, chromium oxide has demonstrated the opposite findings because it functions as a photo-catalytic reagent that accelerated the photo-degradation process. This result may be interpreted as the decomposition of waste PVC, which poses a major threat to the marine ecosystem.

Insights into the evolution of chemical structures in hydrochars from hydrothermal carbonization of PVC

Hydrothermal carbonization (HTC) treatment can induce the comprehensive evolution of PVC structure, which broadens the horizons for the development and optimization of hydrochars derived from PVC. However, there is a lack of understanding of the evolution of chemical structure in hydrochars during the HTC reactions. In this work, the dynamic evolution of the chemical structure of hydrochars during HTC at 220–260 °C within 60 min was comprehensively studied by ultimate analysis, XPS and FTIR. The results showed that hydrothermal temperature had a significant effect on the chemical structure of hydrochars. Raising the hydrothermal temperature facilitated the conversion of C–Cl and C–C/C–H of PVC to C–O, CO, OC–O and CC/C-(C, H), respectively. Under the combined action of hydrolysis, oxidation, aromatization, polymerization and esterification reactions, the hydrochar presented an alicyclic and aromatic structure with different degrees of condensation as its backbone structure. The main oxygen-containing functional groups of the hydrochar were aromatic ethers (C–O), hydroxyl groups (-OH), carboxylic acids (-COOH), and ester groups (-COOR). The maturity of hydrochar was close to that of lignite. Overall, this study provides helpful information for the preparation of diverse value-added products, and also for developing a molecular model of hydrochar for in-depth investigation of the HTC mechanism of PVC.

Using Ultrasonic Reflection Resonance to Probe Stress Wave Velocity in Assemblies of Spherical Particles

A high-sensitivity method to measure acoustic wave speed in soils by analyzing the reflected ultrasonic signal from a resonating layered interface is proposed here. Specifically, an ultrasonic transducer which can be used to both transmit and receive signals is installed on a low-high acoustic-impedance layered structure of hard PVC and steel, which in turn is placed in contact with the soil deposit of interest. The acoustic impedance of the soil (the product of density and wave velocity) is deduced from analysis of the waves reflected back to the transducer. A system configuration design is enabled by developing an analytical model that correlates the objective wave speed with the measurable reflection coefficient spectrum. The physical viability of this testing approach is demonstrated by means of a one-dimensional compression device that probes the stress-dependence of compression wave velocity of different sizes of glass ballotini particles. Provided the ratio of the wavelength of the generated wave to the soil particle size is sufficiently large the data generated are in agreement with data obtained using conventional time-of-flight measurements. In principle, this high-sensitivity approach avoids the need for the wave to travel a long distance between multiple transmitter-receiver sensors as is typically the case in geophysical testing of soil. Therefore it is particularly suited to in-situ observation of soil properties in a highly compact setup, where only a single transducer is required. Furthermore, high spatial resolution of local measurements can be achieved, and the data are unaffected by wave attenuation as transmitted in soil.

Kinetics study on hydrothermal dechlorination of poly(vinyl chloride) by in-situ sampling

Hydrothermal pretreatment has been widely applied as an efficient way to remove chlorine from chlorinated organic wastes while real-time chlorine transformation behaviors and kinetics had not been fully understood. This work investigates on the real-time chlorine transformation characteristics and release kinetics during the hydrothermal dechlorination (HTD) of PVC to propose some powerful solutions to remove chlorine effectively. An online sampling system was designed and operated to collect the gaseous products in-situ. The chlorine in PVC was mainly removed in the form of HCl and then migrated into gaseous products and liquid products. The HTD temperature was the most important factor affecting chlorine removal, followed by residence time. The dechlorination efficiency (DE) was increased from 3.07% to 82.51% when the HTD temperature was risen from 175 °C to 280 °C at a residence time of 30 mins. The chlorine content of gaseous products was accordingly increased from 0.75% to 9.52%. The temperature above 200 °C caused the expansion of PVC and destruction of PVC structure. Besides, the release of HCl generated plenty of pores inside the PVC, enhancing the mass transfer and accelerating the PVC dechlorination. A maximum DE growth rate was observed at the HTD temperature range of 220∼235 °C. At a HTD temperature of 235 °C, the DE was increased from 72.60% to 84.78% when the residence time was prolonged from 15 mins to 60 mins. The kinetics analysis shows the HTD of PVC could be represented by the first-order reaction. According to the Arrhenius law, the apparent activation energy was 217.43 kJ/mol and the HTD reaction of PVC was a chemical reaction control process. This work could provide some fundamental data for the optimization design of hydrothermal pretreatment of chlorine-containing solid waste.

Behavioural responses in the sand tiger shark (Carcharias taurus) to permanent magnets and pulsed magnetic fields

ABSTRACT Sharks are threatened by several human activities that impact their distribution and abundance. A great proportion of shark captures happen as incidental capture (bycatch) by fisheries and in beach nets. Recent studies have focused on reducing these captures by exploiting technologies that target the sharks’ electrosensory system, obtaining contrasting results. This study investigates the effect of a strong neodymium magnet and pulsed magnetic fields (PMFs) on captive sand tiger sharks (Carcharias taurus) through the analysis of their behavioural responses. Firstly, individuals were presented with the magnet in combination with different types of food. The magnet did not influence the sharks’ behaviours, while an effect of the food type emerged. Secondly, PMFs were generated through a pulsed electric current induced within a solenoid associated with a PVC structure. The PMFs affected some of the sharks’ behaviours, both near (<2 m) and at a distance (>2 m) from the source. The results suggest that strong magnets are inefficient in deterring sand tiger sharks, while PMFs could be a promising alternative. This study confirms how the efficacy of shark repellents may be affected by factors such as the type of electrosensory stimuli, the species involved, and the context in which the interaction takes place.

Evaluation of Parameters in the Removal of Linear Alkylbenzene Sulfonate Anionic Surfactant Using Electrocoagulation

The objective of the present investigation was to construct an electrocoagulation cell in a batch system and to evaluate its capacity to remove the anionic surfactant of the linear alkylbenzene sulfonate (LAS), which is present in gray water determining the effect of the type of electrodes (Al or Fe), distance between electrodes (1, 1.5 and 2 cm) and voltages (10, 15 and 20 V). The experimental tests were carried out for 20 min. The dimensions of the short wave electrolysis cell built in glass were 26 cm long, 7 cm wide and 12 cm high, with 10 electrodes of 12x6 cm supported by a PVC structure. The concentration of LAS in the solution was determined by employing UV-Vis spectrometry applying the Methylene Blue Active Substances (MBAS) method. A higher removal of 65.55% was obtained when aluminum electrodes were used, and 69.11% with iron electrodes a separation of 1.5 cm and a voltage of 20 V, presenting less change in pH, conductivity, and energy consumption when using the Al3 electrode. When evaluating the effect of time at the best experimental configuration (Al, 1.5 cm, 20 V) it was established that the removal efficiency increased to 75.13% in 60 min. Electrocoagulation with aluminum electrodes is presented as an efficient alternative for the removal of LAS in solution.

Effect of hydrogen enrichment on the dynamics of a lean technically premixed elevated pressure flame

Abstract The heat release distribution, combustion instability characteristics and flow dynamics of lean swirl-stabilized flames of hydrogen enriched natural gas were studied using time-resolved (10 kHz) stereo PIV, OH* chemiluminescence imaging and acoustic pressure measurements. The technically premixed gas turbine model combustor was operated at elevated pressure up to 5 bar with preheated air. The H2 vol. fraction in the fuel was varied up to 50%. An M-shaped aerodynamically stabilized flame persisted at 1 bar up to low H2 enrichment ratios. Increasing H2 enrichment caused the M-flame to first transition to a bistable flame then to a shear layer stabilized V-flame. Increasing pressure and H2 enrichment both decreased the flame length. The combustion instability frequency and thermoacoustic amplitude varied and were mapped across operating conditions. The effect of H2 enrichment on the thermoacoustic amplitude was explained by examining the convective coupling between the Helmholtz acoustics and heat release. H2 enrichment was shown to increase the phase delay between the pressure and heat release by decreasing the pressure wave travel times in the plenum and swirler sections of the burner and by decreasing the flame length while simultaneously increasing the pressure wave speed within the burner. Thus H2 enrichment increased the thermoacoustic amplitude when the phase delay at the initial condition was negative, and decreased it when the initial phase delay was positive. Flow dynamics were studied by characterizing the precessing vortex core frequency and energy. The PVC structure existed across all conditions, and its frequency reduced to a different Strouhal number for the M-flame and V-flame. H2 enrichment consistently slightly decreased the PVC energy.

Analytical Detection Methodsfor PVC Thin Films Degradation Containing Different Concentrations of Diphenylenehydramine

The head to tail structure of normal PVC should be quite stable to UV radiation. However, the presence of polymer chains abnormalities in the responsible for the relative instability of PVC to light. Therefore, many attempts have been taken to investigate and elevate the photostability PVC. In this work, diphenylenehydramine compound had been used as a photostabilizer to PVC films with different concentrations and its efficiency was evaluated by weight loss percentage, carbonyl index methods after 60 hour of irradiation and surface morphology of PVC.

Preparation and Characterization of Composites Materials with Rubber Matrix and with Polyvinyl Chloride Addition (PVC).

An important problem that arises at present refers to the increase in performances in the exploitation of the conveyor belts. Additionally, it is pursued to use some materials, which can be obtained by recycling rubber and PVC waste, in their structure. Thus, the research aimed at creating conveyor belts using materials obtained from the recycling of rubber and PVC waste. Under these conditions, conveyor belts were made that had in their structure two types of rubber and PVC, which was obtained by adding in certain proportions of reclaimed rubber and powder obtained from grinding rubber waste. In order to study the effect of adding PVC on properties, four types of conveyor belts were made, with the structure of rubber, PVC and textile reinforcement. These have been subjected to certain mechanical tests, also being analyzed from the point of view of the behavior of the accelerated aging. The results obtained showed that the addition of PVC lead to a decrease in tensile stress for the strips made, but also an increase in the tensile strain. Additionally, the elasticity tests performed before and after the accelerated aging showed that the presence of PVC in the structure of the conveyor belts determined a substantial reduction of the aging process of the rubber in the conveyor belts. Under these conditions, it has been established that the use of PVC in the structure of rubber matrix conveyor belts is beneficial if conveyor belts are to be produced that are less subject to mechanical stress, but that work in conditions that can cause accelerated aging of materials. An analysis with the finite element method (FEM) of the test samples was also performed.

Surface modification of white PVC polymer by different plasma immersion techniques

Polymer substrates have several distinct advantages, such as, robustness, low density, impact resistance, and conformity over glass substrates for optical applications. Some applications are impeded, however, owing to its low adhesion to thin films, surface roughness, and low gas permeability. In this work, the wettability and the surface morphology of Poly(Vinyl) Chloride, PVC, samples were modified by plasma immersion. PVC was chosen because of its already wide use and low cost: PVC is used in floor coverings, plumbing, electrical insulation, hoses, containers, and other accessories. In this work, plasma immersion was used to modify the chemical structure of white PVC, producing high values of contact angles (? > 100º) in fluorine plasmas, measured immediately after treatments, and until 30 days after. Also, it was detected low values of contact angles (? < 50º) in nitrogen plasmas. Atomic Force Microscopy revealed smooth surfaces, whose roughness, Rz, was less than ~13 nm, except for plasma immersion cathode, which yielded a Rz of ~213 nm.

The Effect of UV Aging on the Structure of PVC in the Presence of Organotin(IV) Compounds

New photostabilizers of poly(vinyl chloride) (PVC) were synthesized and investigated the photostabilizing efficiency of the polymer films by ultraviolet (UV) experiment. The rate of photodecomposition constant have been calculated for PVC films as a method for evaluating the efficiency of the organotin(IV) complexes that used as a photostabilizers after 300 hour of irradiation. The results have showed that the additives had reduced the rate of photodecomposition constant of PVC films significantly with comparison to PVC (blank). The (kd) value for PVC films was the highest in the absence of any additives, and the lowest value in the presence of triphenyltin (IV) complex.

Modifiers for Rigid Polyvinylchloride Compositions of Building Purpose

A comparison of small doses (up to 0.7 mass part) of impact strength modifiers of foreign and domestic production in polyvinylchloride-based compositions is given. Domestic acrylicnitrile- butadiene styrene modifiers (ABS) were used. The developed shock-resistant polyvinylchloride compositions in the presence of ABS elastifier have high melt fluidity, which has a beneficial effect on the recyclability. Changes in supramolecular structure were estimated from thermomechanical testing and electron microscopy data for both unfilled and filled PVC samples. Thermomechanical analysis showed that the presence of ABS modifier had a favorable effect on the technological properties of PVC-based samples. Electron-microscopic images indicate that in unfilled PVC samples, the heterogeneous PVC structure is expressed in the presence of ABS copolymer in comparison with foreign acrylic modifiers. When the compositions are filled with micro-heterogeneous structure in dispersion medium, the filler-polymer is formed by chalk particles, while ABS elasticifier is at the phase interface. Due to the peculiarities of the structure ABS has a higher degree of “fixation” on the surface of the chalk particles in comparison with the basic compositions containing acrylic modifiers, which with increasing chalk concentration leads to lower wear and tear on the top of the forming equipment.

Potential invasion of the Gulf of Mexico by Protemblemaria punctata (Teleostei: Chaenopsidae), a cryptobenthic fish endemic to Venezuela

The movement of species to areas outside their native ranges has greatly intensified over the past few decades. However, detecting invasive species often requires detailed and regular surveys, especially for animals with small body sizes. A cryptobenthic fish endemic to the Caribbean coast of Venezuela, Protemblemaria punctata (Cervigón, 1966), is reported here from the southwestern Gulf of Mexico, based on the collection of 8 specimens (5 males and 3 females) from Bajo Mersey, a coral reef in the Parque Nacional Sistema Arrecifal Veracruzano (PNSAV). The collected specimens were taken from sessile worm tubes that grew on PVC structures previously placed on the reef at a depth of 6 m. The number of P. punctata specimens we collected could indicate that the species has established a viable population on the reefs in the PNSAV. The colonization of P. punctata in the Gulf of Mexico waters may be due to the dispersal of individuals present on offshore oil platforms that are transported from Trinidad to Venezuela and the Gulf of Mexico.

Acceleration and Inhibition Effect of Tertiary Amines on Thermal Degradation of Poly(Vinyl Chloride)

Poly(vinyl chloride) (PVC) is occasionally discolored yellow or red by the formation of polyene chains in the polymer backbone. It has been noted that the formation of such polyene structures is caused by dehydrochlorination of the PVC, accelerated by tertiary amines. Thus, in the present study, we investigated the influence of amines on the formation of polyene structures in PVC, using resonance Raman spectroscopy. The amount of polyene produced by thermal treatment with amine vapor exposure was determined based on the resonance Raman intensity ratio of the polyene band to the PVC band. The results showed that the discoloration of PVC, indicating the formation of polyene structures, was most prominently caused by 1,4‐diazabicyclo[2.2.2.]octane (DABCO), bis(2‐dimethylaminoethyl)ether (BDMEE), or N,N,N′,N′‐tetramethyl‐1,6‐diaminohexane (TMDAH), because of their high basicity and nucleophilicity. In addition, the formation of polyene structures was inhibited by the co‐presence of amine and protic solvent (water, ethanol, and 2‐propanol) or additives containing hydroxyl groups (glycerin, poly[vinyl alcohol]), suggesting that amine nucleophilicity toward PVC is reduced by the protonation of amine to lone pairs of tertiary amines. J. VINYL ADDIT. TECHNOL., 26:253–258, 2020. © 2019 Society of Plastics Engineers

PVC/LDPE Blends: Relationship Between Thermal/Mechanical Properties, Structure and Blend Behaviour

In this paper the effect of LDPE content in PVC foams are examined on the structure of both the foam and the LDPE. We attempt to understand how LDPE content affects the structure of PVC in blends and how it changes the glass-transition (Tg). These parameters often provide important information related to the overall macromolecular structure of the polymer blend. Thermal analytical techniques such as differential scanning calorimetry (DSC) often used to determine the structural transformation of samples. The effect of the miscibility and composition of the PVC/LDPE foam blends on the thermal stability were also investigated.