Flexible PVC Research Articles

Sustainable approach toward novel poly(vinyl chloride) composite using calcite‐rich waste particulates

AbstractIn this study, flexible poly(vinyl chloride) (PVC) composites with two different types of fillers, precipitated calcium carbonate (PCC) and marble waste (MW) particulates, were prepared via melt processing. The MW collected from a dumping site, had a particle size of approximately 60 μm and high calcite content. The content of fillers and plasticizer was varied to study the effect on the properties of the composites. It was found that at higher plasticizer content (30 phr), MW afforded up to 9% higher tensile strength compared to PCC, indicating a better interfacial adhesion of MW particulates with the matrix. However, at lower plasticizer content (15 phr), composites with PCC exhibited slightly higher tensile strength. Additionally, at high plasticizer content, the addition of MW up to 10 phr afforded better tensile strength than pure PVC. When the composites were fully submerged in the water for 48 h at elevated temperature (60 °C), composite with MW had a slightly higher water absorption (0.4–1.4%) compared to PCC‐filled composites. Also, composite with higher plasticizer showed elevated water uptake at any particular filler content. The study categorically proves the potential of MW in flexible PVC formulations as a cost‐effective sustainable filler.

The electrical response and self-sensing of the fully flexible PVC gel actuator based on flexible electrodes

There has recently been a substantial increase in interest in research on PVC gel actuators because of its numerous advantages over traditional actuators, such as low mass density, large actuation strain, great compliance, and simple manufacturing. However, the current PVC gel actuator is mainly based on the research of rigid electrodes, and there are few researches based on flexible electrodes. In this paper, a fully flexible actuator based on PVC gel film and carbon grease electrode has been prepared. The mechanical properties of the prepared PVC gels with different plasticizer ratios were tested. Three commonly used hyperelastic models (Neo-Hookean, Mooney-Rivlin and Yeoh models) were used to characterize the mechanical properties of PVC gels, and only the Yeoh model was found to be better for the characterization of the mechanical properties of PVC gels. In addition, we used the Prony series to successfully characterize the viscoelasticity of PVC gels. Then, the fully flexible PVC gel actuator (FFPGA) with long-time static and dynamic response characteristics was studied. It was found that the FFPGA has strong viscoelasticity when working. Finally, we proposed to simplify the FFPGA into a capacitor and designed a high-pass filter in the driving circuit. The self-sensing function of the FFPGA was achieved by superimposing a high-frequency low-voltage sensing signal on the low-frequency high-voltage driving signal as the input signal.

Morphological Control of Cilia-Inspired Asymmetric Movements Using Nonlinear Soft Inflatable Actuators.

Soft robotic systems typically follow conventional control schemes, where actuators are supplied with dedicated inputs that are regulated through software. However, in recent years an alternative trend is being explored, where the control architecture can be simplified by harnessing the passive mechanical characteristics of the soft robotic system. This approach is named “morphological control”, and it can be used to decrease the number of components (tubing, valves and regulators) required by the controller. In this paper, we demonstrate morphological control of bio-inspired asymmetric motions for systems of soft bending actuators that are interconnected with passive flow restrictors. We introduce bending actuators consisting out of a cylindrical latex balloon in a flexible PVC shell. By tuning the radii of the tube and the shell, we obtain a nonlinear relation between internal pressure and volume in the actuator with a peak and valley in pressure. Because of the nonlinear characteristics of the actuators, they can be assembled in a system with a single pressure input where they bend in a discrete, preprogrammed sequence. We design and analyze two such systems inspired by the asymmetric movements of biological cilia. The first replicates the swept area of individual cilia, having a different forward and backward stroke, and the second generates a travelling wave across an array of cilia.

Nontoxic Flexible Pvc Nanocomposites with Ta2o5 and Bi2o3 Nanoparticles for Shielding Diagnostic X-Rays

Nontoxic Flexible Pvc Nanocomposites with Ta2o5 and Bi2o3 Nanoparticles for Shielding Diagnostic X-Rays

Synergistic effects of core@double-shell structured magnesium hydroxide microcapsules on flame retardancy and smoke suppression in flexible poly(vinyl chloride).

In order to develop an effective flame retardant for poly(vinyl chloride) (PVC), a core@double-shell structured magnesium hydroxide@9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide@melamine formaldehyde resin (MH@DOPO@ MF) encapsulated flame retardant was prepared. Its flame retardancy and smoke suppression effects in flexible PVC were investigated. Results show that the PVC/10 wt% MH@DOPO@MF composite has the best flame retardancy and smoke suppression performance in comparison with pure flexible PVC and the PVC/20 wt% MH composite. The limiting oxygen index (LOI) of the PVC/10 wt% MH@DOPO@MF composite was ∼30.8%, achieving a V-1 rating in the UL-94 test. MH@DOPO@MF in PVC remarkably increases the yields of the residual char and drastically decreased the heat release rate (HRR), total heat release (THR), smoke production rate (SPR) and total smoke production (TSP). The mechanical property testing showed that MH@DOPO@MF had slight damage on the tensile strength and elongation at break of PVC. This is ascribed to the synergistic flame-retardant effects of MH coordination with DOPO and MF. The present work demonstrates that the core@double-shell structured microcapsule (MH@DOPO@MF) prepared in this efficient manner has good flame retardancy and smoke suppression, and may provide a candidate flame retardant for applying in flexible PVC.

Prediction of The Behavior of Bio-Loaded Flexible PVC by Chicken Feathers with Artificial Neural Networks

The infinite needs of humanity in several fields give birth to several innovations, in materials sciences, these needs are summed up in the creation of new composite materials. Obtaining a composite material from recycled material and a bio-load first of all makes it possible to recover the recycled material and to have new composite material. PVC is one of the most used plastics in recent years, the addition, after recycling, of a bio-load in the form of chicken feathers which are just lost in nature or incinerated, allows the birth of new composite material. In this article, we use neural networks which appear to be among the essential methods to solve and model complex systems, and in particular when it comes to non-linear problems. This method will be used in comparison with the finite element method to find the most adequate method which makes it possible to better model the behaviors of PVC bio-loaded by chicken feathers, and then predict the behaviors with different percentages of the bio-load. We took the results of the experiments carried out, with those of the study of finite elements, and with the results obtained by the neural networks which will be presented in this article, to find the model which makes it possible to better present and predict the behavior of the recycled PVC bio-loaded with an adequate percentage which improves the mechanical characteristics of this type of composite material. The error between the experimental results and those obtained by the neural networks is very small compared to the differences between the two experimental results and those obtained by the finite elements. Which proves that the neural network model is an important computer tool for modeling and predicting the results of mechanical experiments

Experimental study of the mechanical effect of bio-loads on PVC recycling

With the increase in plastic waste, recycling becomes an urgent necessity to reduce and revalue it. PVC is one of the most widely used types of plastic in the world, and indeed it is among the most recycled. The effect of recycling on PVC or any other type of material is to reduce these characteristics, which also depends on the method by which it is recycled. Finding a way to increase the recyclability number of PVC by improving the mechanical characteristics will be an addition at the level of scientific research as well as at the industrial level. The addition of a bio-loading in the form of cow horns, coconut or chicken feathers on the flexible PVC with an experimental study of the results obtained allow to deduce the most adequate bio-loaded material to improve the mechanical characteristics after recycling. The experiments carried out on flexible PVC have shown the effects of bio-loading as well as the degradation brought by recycling on this type of plastic. The results obtained showed an improvement in the mechanical properties of rigid and flexible PVC with a natural bio-loading with the three fibers of coconut, cow horns and chicken feathers which enhance the environment, are very light and can be collected directly from the waste with a large amount.

Preparation of nonmigratory flexible poly(vinyl chloride)-b-poly(n-butyl acrylate)-b-poly(vinyl chloride) via aqueous reversible deactivation radical polymerization in a pilot reactor

Industrially-viable nonmigratory internal plasticization of poly(vinyl chloride) (PVC) is achieved by synthesis of the block copolymer poly(vinyl chloride)-b-poly(n-butyl acrylate)-b-poly(vinyl chloride) (PVC-b-PBA-b-PVC) by aqueous single electron transfer degenerative chain transfer living radical polymerization (SET-DTLRP). The introduction of a temperature step (42 °C to 80 °C) in the synthesis of PVC-b-PBA-b-PVC block copolymers from PBA macroinitiators resulted in materials with better overall performance than the commercial flexible PVC. The resulting copolymers were fully characterized by 1H NMR, SEC, SEM, TGA, DSC and DMTA to determine the composition, molecular weight, dispersity, morphology, thermal and mechanical properties, and compared with those of commercial formulations prepared with PVC and dioctyladipate (DOA). Most importantly, the plasticizing moieties of the PVC-b-PBA-b-PVC block copolymers are covalently bonded to the polymer, resulting in no migration upon extraction under conditions where DOA is readily extractable. Unlike commercial materials, the PVC-b-PBA-b-PVC block copolymers showed that the properties remain intact after extraction with n-hexane.

Effect of gamma dose rate in the crosslinking of PVC composites used for radiation protection in radiology

Flexible PVC composites loaded with various levels of tantalum carbide (TaC) were gamma irradiated at two different dose rates and their effect on crosslinking level, thermal stability and mechanical properties evaluated. The shielding properties of composites against X-Rays at radiodiagnosis energies were also evaluated. Gel percentage results indicate a relatively stable crosslinking level after irradiation, only some reduction was observed for highly loaded composite treated at a low dose rate, although thermal stability observed by TGA was maintained. TaC particles were properly dispersed within the PVC material, as seen by SEM and toughness increased when both E' and E'' Moduli were enhanced after irradiation; even Tg, followed by Tanδ DMA curves, increased noticeably after treatment and for the higher TaC loaded composites, particularly when treated at low dose rate irradiation. Density measurements indicated lighter and manageable materials with respect to traditional shielding items. The shielding properties for composites, evaluated in a clinical X-Ray apparatus, in the 50–129 kV interval, show mass attenuation coefficients close to the ones reported for lead, even higher for 50% TaC loaded composite and a very competitive half-value layer (HVL) for all of them.

Comparison of glass transition dynamics between fluorophore-labeled and -doped flexible Poly(vinyl chloride) plasticized by ultra-small branched star Poly(ε-caprolactone)

Glass transition dynamics are one of the most important characteristics with regards to governing the properties of polymers. Herein, we prepare pyrene-labeled and pyrene-doped flexible poly(vinyl chloride)s plasticized by ultra-small branched star poly(ε-caprolactone) (L-PVC/USB-SPCL and D-PVC/USB-SPCL, respectively), and observe the changes in their fluorescence intensities with temperature to ascertain the actual glass transition behaviors of the polymer chains. Fluorescence spectroscopy measurements show that the D-PVC/USB-SPCLs have a single Tg, which is comparable to the Tg measured by differential scanning calorimetry (DSC). However, the L-PVC/USB-SPCLs exhibit a broad glass transition from the onset of Tg for the L-PVC/USB-SPCLs to the endset of Tg for the PVC chain itself (i.e., in the absence of USB-SPCL). In addition, the L-PVC/USB-SPCLs show a relatively low nonradiative decay degree compared to the D-PVC/USB-SPCLs. These results indicate that the labeled pyrene moieties along the PVC chains exhibited limited movement due to the cooperative reptation motion of the chains, even when the space for the polymer chain to move sufficiently is created by an increase in the free volume. As the USB-SPCL content increase in the flexible PVC, the fluorescence intensity reduction degrees of the various D- and L-PVC/USB-SPCLs decrease due to the polarity effect of USB-SPCL. However, in the case of the L-PVC/USB-SPCLs, when the USB-SPCL loading reach 40 phr, the fluorescence intensity reduction degree increases once again due to the dominance of the decrease in caging effect, which reveals that the labeled system, in which a fluorescent substance is directly attached to a polymer chain, allows identification of the motion of the polymer chain in a direct and sensitive manner.

Fabrication and Measurement of Flexible Polymer Aerogel and Factors Affecting its Thermal Conductivity

Silica aerogels are the most widely studied type of aerogel. However, its application still suffers from low mechanical strength and high production cost. The paper studies the use of recyclable PVC as the backbone material of the aerogel and introduces an economically friendly fabrication process of flexible PVC aerogel using sol-gel technique and ambient drying instead of the CO2 critical drying. Three different types of PVC powder with the molecule weight of 43000, 48000, and 80000 respectively are chosen and dissolved in DMF in five different concentrations-0.2, 0.4, 0.6, 0.8, and 1.0 g (mL)-1. The lowest thermal conductivity of the aerogel is measured using hot-wire method as 0.0323W(m*K)-1, which is made of PVC with molecule weight of 80000 in a concentration of 0.4g (mL)-1. The analysis based on SEM pictures shows that PVC type and concentration would greatly influence aerogel’s structure thus affecting its thermal conductivity. The optimal solution for producing low thermal conductivity aerogel is to use PVC powder with low molecule weight with a concentration between 0.2 and 0.6 g (mL)-1.

Tris(hydroxymethyl)aminomethane and its derivative as organic thermal stabilizers for flexible poly(vinyl chloride)

AbstractThe tris(hydroxymethyl)aminomethane (THAM) and its derivative (DHD 2‐([1,3‐dihydroxypropan‐2‐ylidene]amino)‐2‐(hydroxymethyl)propane‐1,3‐diol) have been used as organic thermal stabilizers for flexible poly(vinyl chloride) (PVC). According to dehydrochlorination and discoloration tests conducted at 180°C, THAM showed to be an excellent organic thermal stabilizer for flexible PVC, not only THAM stabilizer improved the thermal stability of PVC but also maintained the initial color of the PVC. The induction time and the thermal stability time were 52 and 55.5 min, respectively. DHD can also be used as an organic thermal stabilizer for flexible PVC; however, its thermal stabilizing efficiency was not satisfactory, but it has a good synergistic effect with traditional cadmium–zinc soap stabilizers. Besides, the experiments had been performed to investigate pentaerythritol (PER) and THAM, two substances with similar structure, but such a huge difference in thermal stabilizing efficiency for flexible PVC. THAM did improve the thermal stability of PVC, both in initial whiteness and long‐term thermal stability. But PER has no thermal stabilizing efficiency for PVC when used alone. At the end of the article, the probable mechanism which can give an explanation for the stabilizing efficiency given by the THAM has been proposed.

Tunable Stiffness and Damping Study on Flexible PVC Cantilever Structure Embedded with MR Fluid.

The stiffness and damping of a flexible smart cantilever structure controlled by a magnetic field is investigated in this research. The cantilever structure is fabricated by using flexible polyvinyl chloride as a host structure of rectangular cross-section embedded with magnetorheological (MR) fluid. The deflection of the cantilever structure at the free end is used to analyze the stiffness change of the cantilever structure. The stiffness of the specimen with MR fluid at magnetic flux density of 0.171 T is greater than that of the specimen without subjected to magnetic field. The strength of the applied magnetic field is directly related to the structure’s stiffness. Under the influence of a magnetic field, the MR fluid embedded inside the flexible PVC cantilever structure significantly dampens the vibrations of the structure.

Energy and exergy analyses of a helicoidal water to air geothermal heat exchanger for arid regions

ABSTRACT Helicoidal water-air geothermal heat exchanger (HWAGHE) uses the water well as a heat source/sink for air refreshing purposes in space. It has been exploited as a passive technique to minimize the energy uses in buildings. This work goals to estimate the energy and exergy characteristics of HWAGHE for arid zone weather condition of Algeria. The helicoidally geometry enhancing the heat exchange with the soil is chosen to decrease the operating cost and the needed area. The studied HWAGHE was constructed from a flexible PVC pipe with 30 m length and 0.6 m diameter. It was immersed into a drilled borehole with 1 m diameter and 5 m depth. The heat exchange rate with the ground and exergy and energy efficiencies of HWAGHE is evaluated. Experimental findings revealed that the inlet ambient temperature has a considerable impact on the HWAGHE performances mainly when the change in temperature between the ambient and the water well increments. Maximal exergy and energetic efficiencies of the HWAGHE, reaching 89% and 92%, respectively, are obtained at 0.035 kg s−1 mass flow rate.

Inverse modeling of thermal decomposition of flame-retardant flexible PVC with model-free coupled with model-fitting method

The thermal decomposition model of flame-retardant flexible PVC is essential for relevant waste management and predicting its fire behavior. In this work, thermal decomposition kinetics of this material was investigated via thermogravimetric analysis in non-isothermal conditions. The kinetic analysis was performed using model-free (including Kissinger, Friedman, and advanced Vyazovkin methods) coupled with model-fitting method (Ant Lion Optimization algorithm, ALO). The kinetic parameters obtained from model-free method provide guides for initial guess and search range for ALO. Two different decomposition models are developed and the validations show that second two-step parallel model could better predict experimental data and explain the decomposition process. The performance of ALO is compared with Shuffled Complex (SCE) Evolution algorithm. The results show that the ALO shows better performance because all solutions from SCE are trapped in local minima. In this way, the ALO could be used as an alternate optimization tool for inverse modeling.

Thermal properties and fire behavior of a flexible poly(vinyl chloride) modified with complex of 3-aminotriazole with zinc phosphate

The complex of zinc phosphate and 3-amine-1,2,4-triazole (ZN3AT) was synthesized by a one-pot reaction and used as an intumescent flame retardant (IFR) for flexible poly(vinyl chloride) (PVC). The thermal properties and fire behaviour of flexible PVC with 20 wt% of ZN3AT were investigated and compared with unmodified PVC and PVC with commercial IFR. The thermal stability and burning behaviour were evaluated by thermogravimetric analysis (TGA) as well as cone calorimetry and horizontal burning tests. Furthermore, the analysis of volatile products evolved during the thermal decomposition and burning was performed using TGA and steady state tube furnace, both coupled with FT-IR. PVC containing developed flame retardant exhibits the lowest total heat release and smoke emission of all investigated samples. Materials analysis supplemented with analysis of their mechanical and thermomechanical properties shows that despite the high concentration of the IFR its incorporation did not strongly influence the properties of final products in comparison to pure PVC.

Analysis of the dependence of stresses and deformations on the surfaces of shoe soles of different thicknesses and materials

For this study, three-dimensional models of the soles of work shoes of different thicknesses and consisting of different materials were created. These models were analyzed to obtain the distribution of stress and strain on their surfaces. To build the model, we used experimental data on the shape and size of the sole, as well as the properties of specific materials used in the manufacture of soles for work shoes used in agriculture. The goal was to determine the most suitable material, that is, which of the materials has the most suitable characteristics for the sole, has the best wear resistance when used in agriculture. We noticed a significant reduction in deformations on the surface of the sole with an increase in the thickness of the sole, as well as when using two-component casting of the sole from a combination of materials: low-density EVA and flexible PU, medium-density EVA and soft PVC. This indicates their advantages and maximum suitability.

Numerical Study of the Use of Tyre-Derived-Aggregate (TDA) as the Backfill Above Flexible PVC Pipeline

Tyre Derived Aggregates (TDA), produced by shredding scrap car tyres, show many interesting features, such as: durability, low bulk density, thermal insulation, good drainage properties or ability to damp vibrations, which makes them a useful material for civil engineering. One of the possible applications is the partial filling of excavations with TDA during the construction of underground pipelines in order to decrease the load applied on the pipe. The article presents results of a multivariate numerical study of 2D FEM models of a flexible PVC pipe - soil system, in which the presence of a mixture of sand and TDA (tyre chips - 40% by weight) (STCh) in the backfill was simulated. The models differed in the thickness of the STCh layer (t = 0 – 0.9 m) and inclination of the excavation walls (a trench with vertical walls or open excavations with 3:1 and 1:1 slopes). The main goal of the numerical analyses, performed by means of the Z_Soil.PC program, were to investigate the effect of the presence of the softer STCh layer in the backfill zone on the pipe deformation (relative deflection δ/D) and internal forces in the pipe wall. The soil was simulated with the use of either the Hardening Soil Small (HSS) or Coulomb-Mohr (CM) constitutive model with the parameters’ values estimated based on results of laboratory tests (published by researchers from Wollongong University). The PVC pipe was modelled as linear elastic. The results of the analyses show that, due to enhanced arching, STCh layer of the optimum thickness t = 0.55 m can effectively reduce δ/D when used in the backfill of the trench. It can also decrease the difference between the maximum and minimum bending moment in the pipe wall, leading to less ovalization of the pipe cross-section. This positive effect diminishes if the width of excavation is larger, as the model is gradually transforming towards the positive projecting conduit type. The CM model gives underestimated values of the pipe deformation and internal forces. Though, in the case of lack of all the HSS parameters’ values, it is better to use the CM model with E = E 50 than E = E ur as it gives a better approximation of pipe behaviour.

An Overview of the Flame Retardants for Poly(vinyl chloride): Recent States and Perspective†

As a versatile star product, poly(vinyl chloride) (PVC) has kept active in our daily life all through since it was invented. However, the severe fire hazard and heavy smoke produced during combustion, particularly the extensively used flexible PVC products, have been puzzling manufacturers and researchers for ages. Over the last decade, multifarious flame retardants and smoke suppressants were developed for PVC materials. In this review, combined literature with the results based on the research from our group, recent emerged flame retardants and smoke suppressants for PVC are introduced. Meanwhile, the flame retardant mechanisms and experimental analysis results are described to understand the relationship between characters of flame retardants (including chemical compositions, structures or morphologies) and fire performance of the composites. The potential substitutes for traditional harmful flame retardant antimony trioxide are discussed aiming to the emphasis on increasing prominent environmental concerns. In particular, one section is dedicated to new approaches for the preparation of novel environmentally friendly and high‐efficiency flame retardants. It is hoped that this review will not only summarize the new emerged flame retardants and smoke suppressants for PVC, but also provide the new trend to prompt sequent exploration in both academic research and industrial application.

An innovative approach for temperature control of massive concrete structures at early ages based on post-cooling: Proof of concept

This study proposes a new methodology for the embedment of flexible PVC hoses (with the shape/geometry of the intended cooling pipes) that allows their removal a few hours after casting (i.e. after setting), while allowing that water is pumped through the circular cavity afterward (through a flexible/impermeable sleeve placed to shield the exposed concrete cavity). The PVC hoses are initially filled with oil under pressure, which are deflated a few hours after casting (particularly after setting is identified), and removed without relevant constraints due to their reduction in diameter inherent to deflation. All components and materials embedded into concrete (hose, sleeve) are fully recoverable after the end of the temperature control period, avoiding the loss of materials, with important financial and sustainability gains. This paper intends to show the proof-of-concept carried out in laboratory context conditions, highlighting the features that led to the selection and phasing procedure of the solution proposed.