Poly Vinyl Chloride Samples Research Articles

Investigation into time evolution of chlorine emission in pulsed CO2 laser induced breakdown spectroscopy (LIBS)

Detection of chlorine (Cl) using LIBS technique is greatly influenced by experimental conditions including the delay time of the detecting device. Time evolution of Cl emission in plasma produced on polyvinyl chloride (PVC) sample using CO2 laser with variation of delay time has been carried out. The plasma was produced at atmospheric pressure under different environment of helium and air, respectively. It was found that when using the pulse energy of 750 mJ under helium surrounding, strong emission line of Cl at 479.45 nm can be observed until 4 μs of delay time, while when using laser energy 2500 mJ strong Cl emission line can be observed until 7 μs. The higher signal to background ratio was observed at delay time of 1 μs. However, Cl emission line cannot be detected under air environment.

Experimental Study of Electric and Dielectric Behavior of PVC Composites

Polyvinyl chloride (PVC) is usually used as insulation in electrical engineering, mainly as cable insulation sheaths. A method for improving PVC’s dielectric properties, reducing the effects of UV aging, is the use of PVC films doped in alumina and titanium dioxide. This research investigated the influence of alumina and titanium dioxide (Al2O3/TiO2) on the dielectric properties of PVC. Four PVC samples were examined using an RLC impedance analyzer. Fourier Transform Infrared (FTIR) spectroscopy was utilized on the sample’s surfaces, exploring the chemical stability of the tested materials. In addition, the volume resistivity and average breakdown voltage of each sample were examined. Doping Al2O3/TiO2 into PVC improved its dielectric properties and volume resistivity while adding more ceramic decreased volume resistivity. Furthermore, the addition of Al2O3/TiO2 caused a significant enhancement in voltage breakdown strength.

Surface functionalization of polyvinyl chloride by plasma immersion techniques

In this work we discuss the wettability, chemical composition, surface morphology and optical transmittance of polyvinyl chloride (PVC) samples treated by Plasma Immersion and by Plasma Immersion Ion Implantation. The total pressure of N2 or SF6 was 6.66 Pa, for treatments of 900 s, applied rf power of 25 and 100 W, and the substrate temperature was about 298 K. In PIII, high voltage pulses of -2400 V at a cycle time of 30 µs and a frequency of 300 Hz were used. The wettability of the samples was assessed via contact angle measurements, which indicated either hydrophilicity or hydrophobicity, depending on the plasma composition. X-ray Photoelectron Spectroscopic analysis confirmed strong fluorine attachment to the surface after treatments using SF6 plasmas, and the presence of oxygen after treatments using nitrogen plasmas. Atomic Force Microscopy images showed that the roughness Rrms, depends on the plasma conditions. Optical transmittance in the visible region, T (λ), was increased by plasma immersion. The greatest contact angle observed was 142º (PI cathode), while the highest roughness was 213.2 nm. The highest optical transmittance in the visible region was around to 90% (PI anode).

Effect of UV/ozone treatment on the wettability and adhesion of polymeric systems

ABSTRACT The impact of UV/ozone treatment on the wettability and adhesion of ethylene propylene diene methylene (EPDM) rubber, polyvinyl chloride (PVC), and acrylonitrile butadiene styrene (ABS) was investigated using contact angle measurements, OWRK surface free energy model, standardized adhesion tests, and spectroscopic and microscopic observations. It is found that UV/ozone treatment enhances the wettability of the examined polymers. Also, it considerably improved the adhesion strength of PVC and ABS samples, and shifted their failure modes from adhesive to cohesive. FTIR-ATR characterization showed insignificant changes in the chemical structures of the studied materials. However, SEM observation showed newly-created wrinkles and micro-holes on treated PVC surfaces, and micropores on ABS surfaces. These UV-induced morphological changes on PVC and ABS surfaces increased the surface area which can promote the mechanical interlocking with the adhesive. This explains the improvement of their adhesion strength. Implications of the current study for the processing of strongly bonded polymeric joints are discussed.

Degradation of unplasticised poly vinyl chloride based engineering products upon exposure to ultra violet radiation

Poly vinyl chloride (PVC) is considered as a widely used polymer for various applications. It is durable, inexpensive and resistant to heat, water and chemicals. Additives such as lubricants, heat stabilizers, plasticizers, impact modifiers, fillers and ultra violet (UV) stabilizers enhance its durability and make it suitable for a range of applications. PVC is used for automobile and other sectors in products ranging from piping and siding, blood bags and tubing, to wire and cable insulation applications. Poly vinyl chloride exhibits high sensitivity to UV rays and it is a life time deciding factor specially in outdoor applications. This study was conducted to analyse the degradation behavior of PVC under the UV environment. Commercially available 32mm PNT7 unplasticised poly vinyl chloride (uPVC) pipes were selected for this research. Initially, tensile strength, elongation, hardness and water absorption properties were analysed. Ultra violet ray exposure test was performed for PVC samples to evaluate the photo-degradation behavior at selected UV exposure time periods. Tensile strength, elongation, hardness, water absorption properties and visual inspection tests were performed after the UV exposure test. Scanning electron microscopic images and differential thermal analysis were also used to analyze the degradation behavior. It was indicated a slight reduction of tensile strength, percentage elongation and hardness of samples with increase of UV exposure time. Scanning electron microscopic images of products showed degraded features after UV exposure test. This study revealed that uPVC based products are resistant to photodegradation by UV rays.

Energy dependence of Cl emission lines in CO2 laser induced breakdown spectroscopy

Chlorine (Cl) detection using laser induced breakdown spectroscopy (LIBS) techniques in geology and environment samples is still challenging since the experimental conditions greatly influence the analytical performance of LIBS. Cl emission in LIBS must be studied carefully to find the optimum condition to allow Cl detection. In the present study, Cl emission was studied from polyvinyl chloride (PVC) sample containing Cl as major element. A Transversely Excited Atmosphere (TEA) carbon dioxide (CO2) laser was used for inducing plasma from the sample. Cl emission was investigated by varying the experimental conditions, especially energy of the laser pulse. The emission spectrum from the consequent plasma was detected using an Optical Multichannel Analyzer (OMA) system. It was found that Cl emission lines only can be obtained when helium was used as the surrounding gas. The strongest emission line of Cl I 837.59 nm in the infrared region cannot be detected even under helium surrounding gas. Instead, many ionic emission lines of Cl in ultraviolet regions including the strong ionic lines (Cl II 479.45 nm, Cl II 481.00 nm, Cl II 481.94 nm and the weak lines (Cl II 476. 86 nm, Cl II 478.13 nm, Cl II 489.67 nm, Cl II 490.47 nm and Cl II 491.77 nm) can unequivocally be detected. It was also found that the intensity of Cl emission lines critically depends on the energy of the laser pulse, namely the emission intensity of Cl lines increases sharply with energy. In present work, the highest intensity of Cl emission lines was obtained when the energy of the laser pulse was about 2500 mJ, giving strong and clear Cl emission lines with low background and relatively high signal to background ratio of more than 3.

New Formulations of Flame-retardant Flexible Polyvinylchloride Composites

The composition of electrical wires and cables is of critical importance in controlling fire risks. In this respect, polyvinylchloride (PVC) composites are extensively used. Yet, PVC composites are multiple systems in which the final properties depend on the nature and size of the reinforcement or flame-retardant agent and the type of lubricant used for their preparation. Thereby, in this study two series of PVC composites, with stearic acid and calcium stearate as lubricants were prepared in parallel, and additivated with various commercial minerals as reinforcement/flame retardant agents, such as calcium carbonate, alumina trihydrate (ATH) and HMH (a mineral of hydromagnesite and huntite). Following the structure (by FT-infrared), thermal behavior (thermal analyses and differential scanning calorimetry) and mechanical properties (dynamic mechanical analyses, tensile strength and elongation at break) of PVC composites, the flame-retardant effect of the selected minerals was investigated by measuring the limiting oxygen index (LOI). Only ATH and HMH-based composites presented higher flame-resistance, relative to the control samples, making them suitable for the proposed application. The contact angle was evaluated for determining the hydrophobicity of composites when using ATH or HMH, to get an opinion about the stability of the materials in moist environments. Finally, SEM was used to determine the homogeneity of PVC samples.

Electrochemistry on Tribocharged Polymers

Static electrification of insulators is a familiar topic: hair attracted by a party balloon or ink or laser printers transferred to a toner1. Contact electrification develops on the surface of insulators which are brought in and out of. Statically charged surfaces has been known to mediate redox work, but the scope in electrochemistry of charged dielectrics remains poorly understood. In 2008, Liu and Bard demonstrated that metal ions can be reduced to elemental metal on a charged polytetrafluoroethylene surface and they proposed that charge carries are electrons2. However, in 2011, Bartosz A. Grzybowski demonstrated a random “mosaic” of each polymer surface after contact and separated, suggesting that polymer fragments are responsible of the electrification process3. Here we report that the magnitude of electrochemical work on electrostatically-charged polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC) samples is material-dependent. We show that the magnitude of redox work mediated by a charge insulator is governed by a trade-off between its ionization energy (IE) and electron affinity (EA)4. Using XPS, AFM and TEM we have quantified metal deposition on electrostatically-charged PDMS, PTFE and PVC samples. Quantum chemical methods are used to show that anions are the effector of the redox work and polymer, with plastics of the largest negative value of EA (making negative charges unstable) but that at the same time it will ionize into cationic fragments with relative ease, leads to surfaces able to mediate redox work to the largest extent. This work extends our understanding of the molecular nature of static electricity and may find applications in single-electrode electrochemistry and in the study of electrostatic catalysis on chemical reactivity. References Childress, C. O.; Kabell, L. J., Electrostatic Printing System. US Patent No. 3,081,698, 163: 1963. Liu, C.-Y.; Bard, A. J., Electrostatic Electrochemistry at Insulators. Nat. Mater. 2008, 7 (6), 505–509. Baytekin, H.; Patashinski, A.; Branicki, M.; Baytekin, B.; Soh, S.; Grzybowski, B. A., The Mosaic of Surface Charge in Contact Electrification. Science 2011, 333 (6040), 308–312. Zhang, J.; Rogers, F.; Darwish, N.; Gonçales, V. R.; Vogel, Y. B.; Wang, F.; Gooding, J. J.; Peiris, M. C.; Jia, G.; Veder, J.-P., Electrochemistry on tribocharged polymers is governed by the stability of surface charges rather than charging magnitude. Journal of the American Chemical Society 2019. Figure 1

Growth of Metal Nanoparticles on Electrostatically-Charged Polymers

Growth of Metal Nanoparticles on Electrostatically-Charged Polymers Jinyang Zhang and Simone Ciampi* School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia Static electrification of insulators is a familiar topic: hair attracted by a party balloon or ink or laser printers transferred to a toner1. Contact electrification develops on the surface of insulators which are brought in and out of. Statically charged surfaces has been known to mediate redox work, but the scope in electrochemistry of charged dielectrics remains poorly understood. In 2008, Liu and Bard demonstrated that metal ions can be reduced to elemental metal on a charged polytetrafluoroethylene surface and they proposed that charge carries are electrons2. However, in 2011, Bartosz A. Grzybowski demonstrated a random “mosaic” of each polymer surface after contact and separated, suggesting that polymer fragments are responsible of the electrification process3. Here we report that the magnitude of electrochemical work on electrostatically-charged polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC) samples is material-dependent. We show that the magnitude of redox work mediated by a charge insulator is governed by a trade-off between its ionization energy (IE) and electron affinity (EA)4. Using XPS, AFM and TEM we have quantified metal deposition on electrostatically-charged PDMS, PTFE and PVC samples. Quantum chemical methods are used to show that anions are the effector of the redox work and polymer, with plastics of the largest negative value of EA (making negative charges unstable) but that at the same time it will ionize into cationic fragments with relative ease, leads to surfaces able to mediate redox work to the largest extent. This work extends our understanding of the molecular nature of static electricity and may find applications in single-electrode electrochemistry and in the study of electrostatic catalysis on chemical reactivity. References Childress, C. O.; Kabell, L. J., Electrostatic Printing System. US Patent No. 3,081,698, 163: 1963. Liu, C.-Y.; Bard, A. J., Electrostatic Electrochemistry at Insulators. Nat. Mater. 2008, 7 (6), 505–509. Baytekin, H.; Patashinski, A.; Branicki, M.; Baytekin, B.; Soh, S.; Grzybowski, B. A., The Mosaic of Surface Charge in Contact Electrification. Science 2011, 333 (6040), 308–312. Zhang, J.; Rogers, F.; Darwish, N.; Gonçales, V. R.; Vogel, Y. B.; Wang, F.; Gooding, J. J.; Peiris, M. C.; Jia, G.; Veder, J.-P., Electrochemistry on tribocharged polymers is governed by the stability of surface charges rather than charging magnitude. Journal of the American Chemical Society 2019. Figure 1

Internal plasticization of poly(vinyl) chloride using glutamic acid as a branched linker to incorporate four plasticizers per anchor point

ABSTRACTInternal plasticization of polyvinyl chloride (PVC) using thermal azide‐alkyne Huisgen dipolar cycloaddition between azidized PVC and electron‐poor acetylenediamides incorporating a branched glutamic acid linker resulted in incorporation of four plasticizing moieties per attachment point on the polymer chain. A systematic study incorporating either alkyl or polyethylene glycol esters provided materials with varying degrees of plasticization, with depressed Tg values ranging from −1 °C to 62 °C. Three interesting trends were observed. First, Tg values of PVC bearing various internal plasticizers were shown to decrease with increasing chain length of the plasticizing ester. Second, branched internal plasticizers bearing triethylene glycol chains had lower Tg values compared to those with similar length long‐chain alkyl groups. Finally, thermogravimetric analysis of these internally plasticized PVC samples revealed that these branched internal plasticizers bearing alkyl chains are more thermally stable than similarity branched plasticizers bearing triethylene glycol units. These internal tetra‐plasticizers were synthesized and attached to PVC‐azide in three simple synthetic steps. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1821–1835

Characterizing mechanical and medical imaging properties of polyvinyl chloride-based tissue-mimicking materials.

Polyvinyl chloride (PVC) is a commonly used tissue‐mimicking material (TMM) for phantom construction using 3D printing technology. PVC‐based TMMs consist of a mixture of PVC powder and dioctyl terephthalate as a softener. In order to allow the clinical use of a PVC‐based phantom use across CT and magnetic resonance imaging (MRI) imaging platforms, we evaluated the mechanical and physical imaging characteristics of ten PVC samples. The samples were made with different PVC‐softener ratios to optimize phantom bioequivalence with physiologic human tissue. Phantom imaging characteristics, including computed tomography (CT) number, MRI relaxation time, and mechanical properties (e.g., Poisson’s ratio and elastic modulus) were quantified. CT number varied over a range of approximately −10 to 110 HU. The relaxation times of the T1‐weighted and T2‐weighted images were 206.81 ± 17.50 and 20.22 ± 5.74 ms, respectively. Tensile testing was performed to evaluate mechanical properties on the three PVC samples that were closest to human tissue. The elastic moduli for these samples ranged 7.000–12.376 MPa, and Poisson’s ratios were 0.604–0.644. After physical and imaging characterization of the various PVC‐based phantoms, we successfully produced a bioequivalent phantom compatible with multimodal imaging platforms for machine calibration and image optimization/benchmarking. By combining PVC with 3D printing technologies, it is possible to construct imaging phantoms simulating human anatomies with tissue equivalency.

$W$ -Band Complex Permittivity Measurements at High Temperature Using Free-Space Methods

Free-space measurement techniques can be contactless and are able to accommodate large, flat sheets of dielectric material, making them useful for characterization of high-temperature, millimeter-wave, window and radome candidate materials. As part of the present work, a high-temperature, W-band (75–110 GHz), free-space measurement system was developed and used to characterize complex dielectric properties of bulk material samples at temperatures ranging from 25 °C to 600 °C. Two test cases, polyvinyl chloride (PVC) and CoorsTek 92% alumina, were measured at 25 °C and found to have $\boldsymbol {\epsilon }_{r}^\prime $ values of 2.731 ± 0.005 and 8.061 ± 0.027 at 95 GHz, respectively. The 25 °C PVC sample was measured to have a $\boldsymbol {\epsilon }_{r}^{\prime \prime }$ value of 0.032 ± 0.007. At 25 °C, the $\boldsymbol {\epsilon }_{r}^{\prime \prime }$ value of the 92% alumina sample was below the uncertainty threshold achievable with the present free-space measurement apparatus and could only be bounded to $\boldsymbol {\epsilon }_{r}^\prime $ and $\boldsymbol {\epsilon }_{r}^{\prime \prime }$ values increased to 8.501 ± 0.028 and 0.035 ± 0.008, respectively. The high-temperature behavior of the authors’ 92% alumina ceramic was found to be similar to that previously documented for Sumitomo AKP-50 alumina over the 25 °C–600 °C temperature range. In addition to the 92% alumina sample, three commercially available ceramic substrates (zirconium oxide, boron nitride, and silicon nitride) were also characterized at temperatures ranging from 25 °C to 600 °C.

Improving the nondestructive analysis accuracy of liquids in a flexible container based on the multi-pathlength spectrum method

In order to achieve nondestructive analysis of liquid samples, the spectral analysis of solution in a flexible container is proposed in this paper. However, the difference in the flexible containers reduces the accuracy of the spectral analysis. By analyzing the relationship between the condition number of coefficient matrix (CNCM) and the solution accuracy, a method of reducing CNCM by multi-pathlength spectrum is proposed to reduce the error caused by the differences in flexible containers. To verify the feasibility of the method, different concentrations of samples were prepared with intralipids and India-ink, and polyvinyl chloride sample tubes were used as the flexible container. The experimental results show that the proposed strategy can effectively reduce the error caused by the differences in flexible containers.

Preparation of epoxidized sunflower oil metal soap derivatives and their use asheat stabilizers for polyvinyl chloride

The aim of this work was to prepare metal soaps of epoxidized sunflower oil (ESO) and use them as thermal stabilizers for polyvinyl chloride (PVC). For that purpose, commercial sunflower oil was first epoxidized and then used to prepare (Ba, Zn, Pb, and Cd) metal soap derivatives, which were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The prepared metal soaps derivatives of ESO were used as thermal stabilizers for plasticized PVC. Discoloration, residual thermal stability at 200 $^{\circ}$C , and rheological properties of PVC samples were tested. The structural modifications were investigated by UV-visible spectroscopy. The best thermal stabilization effects were observed in the presence of Pb soap of ESO. Furthermore, metal derivatives of ESO were classified according to their stabilizing effect as follows: Pb-ESO > Ba-ESO > Cd-ESO > ESO > Zn-ESO.

Triacetin as a Secondary PVC Plasticizer

The use of biobased plasticizers with low toxicity and good compatibility with polyvinyl chloride (PVC) has become more attractive in the recent years in contrast with phthalate derivatives. In this study, a glycerol derivative plasticizer (triacetin—TAG) was tested as a secondary plasticizer for PVC. TAG was added to PVC formulations from 10 up to 20 phr. The increase of the plasticizer content had a great influence on the properties of PVC samples. The good miscibility and therefore the efficient plasticization action of the TAG were supported by DMA results, since narrow peaks of tan (δ) curves and reduction of the Tg values for the samples were observed. The ensuing PVC demonstrated good rheological properties and thermal stability up to 200 °C. Finally, the presence of TAG reduces the hardness of materials and does not increase their density.

A study of the effect of silica particles addition on some physical properties of PVC as a packaging material

In this work, varying compositions of SiO2 micro filler were addedwith the Polyvinyl Chloride (PVC) and samples have been preparedusing film casting technique. The results have been analyzed andcompared for PVC samples with (1 wt%, 3 wt%, 5 wt% and 10 wt%)SiO2 micro filler. Mechanical characteristics such as tensile strength,elongation at break and Young`s modulus were measured for all thesamples, where the tensile strength was increased from 8.39 Mpa forpurified PVC to 16 Mpa for 3% SiO2/PVC composite. Also, thermalconductivity measurement values illustrated that composite materialshave a good thermal insulation at 10 wt. %, thermal conductivity wasdecreased from 0.1684 W/m. K for PVC to 0.1310W/m. K at 10%SiO2/PVC composite. Absorptivity test was also carried out for thesesamples, the results of this study proved that PVC and SiO2-PVCcomposites have low diffusion coefficients ranging from (10-13- 10-10m2/s). Similarly, the dielectric properties like dielectric constant, lossfactor, resistance, and volume resistivity were performed; thedielectric constant was increased from 2.1039 for PVC to 3.658 for3% SiO2/PVC composites, while the dielectric loss factor wasdecreased from 0.0144 for PVC to 0.0137 for 5%SiO2/PVCcomposite. The values of resistance were increased from17259.99(Ω) for purified PVC to 29185.75(Ω) for 10% SiO2/PVCcomposites. Volume resistivity was increased from 0.3794 x109 (Ω.cm) for PVC to 0.5179x109 (Ω. cm) for 10% SiO2/PVC composites.FTIR spectroscopy was employed for all PVC-composite samplesand its results were investigated, there are systematic increases inabsorbance intensity spectra with SiO2 ratios attributed to gooddistribution of inorganic fillers (Symmetric increases). Themicrostructure and morphology of the prepared samples wereinvestigated by using optical microscope. It can be observed that, thesamples with (3% SiO2/PVC) are glossy and smooth withoutagglomeration of (SiO2) particles in (PVC) matrix. The resultsdemonstrate that PVC-composite films prepared in this study showpromising potential to achieve good materials for plastic packagingapplications.

Methyl Acetyl Ricinoleate as Polyvinyl Chloride Plasticizer

The use of alternative plasticizers with low toxicity and good compatibility with polyvinyl chloride (PVC) has become more attractive in the recent years in contrast with the phthalate derivatives. In this study, an additive derived from castor oil (methyl acetyl ricinoleate—MAR) was tested as a plasticizer for PVC. MAR was added to PVC in a range of 50–90 PHR and the increase of the plasticizer content had a great effect on maximum tension and tension at 100% of PVC samples. Moreover, the elongation at break also increased with the increase of plasticizer content. The good miscibility with PVC and therefore efficient plasticization action of MAR were proved by the DMA results, since narrow peaks of tan (δ) curves were observed. Moreover, the increase of MAR content reduced the Tg values of the samples [from 8.2 °C (50 PHR) to − 25.6 °C (90 PHR)]. PVC samples obtained using this bio-based plasticizer demonstrated good rheological properties [the increase of plasticizer content increased the MFI from 3.977 (50 PHR) up to 44.244 g.10 min−1 (90 PHR)] and proved to be thermally stable up to 200 °C. Finally, the MAR PVCs presented lower densities and lower hardness when compared with those produced from traditional plasticizes which are important aspects for the manufactories and consumers of PVC. In that sense, MAR proved to be a suitable plasticizer for PVC which may find a broad range of applications in the electric wires, carpets, hoses, shoes and construction industry, among many others.

Nanotubes as polymer composite reinforcing additive materials – A comparative study

Nitrogen-doped bamboo-shaped carbon nanotubes (N-BCNTs) and their non-doped conventional counterparts, multiwalled carbon nanotubes (MWCNTs) were compared as polymer reinforcing additives in polyvinyl chloride (PVC) matrix. The nanotubes were synthetized by catalytic chemical vapor deposition (CCVD) method. The purity of both nanotubes was measured by thermogravimetric analysis (TGA) and found to be >91%. Further analysis on the morphology and size of the carbon nanotubes (CNTs) were performed by transmission electron microscopy (TEM). The PVC powder was impregnated with CNTs in ethanol by using tip ultrasonicator. The dispersion media was evaporated, and the CNT/PVC powder was used to produce polymer fibers. The orientation of carbon nanotubes in the PVC matrix was characterized by scanning electron microscopy (SEM), and the presence of nanotubes were confirmed in case of all PVC samples. It can be observed on the SEM images that the nanotubes are fully covered with PVC. The tensile strength of the nanotube containing samples was tested and the N-BCNT/PVC composite was found to be better in this sense, thanks to the extraordinary structure of the nanotube. In case of the N-BCNT/PVC composite the measured young modulus was 39.7% higher, while the elongation at brake decreased by 33.6% compare to the MWCNT/PVC composite. These significant differences in the mechanical properties of the composites can be explained with the stronger interaction between N-BCNTs and PVC.

The Position of Solid Carbon Dioxide in the Triboelectric Series

The process of releasing liquid carbon dioxide from a fire extinguisher is accompanied by a strong static charging of the plastic material making up the extinguisher discharge horn. Firefighters often report an electric shock when operating CO2 extinguishers, but the origin of this electrostatic hazard is largely unknown. Here, we begin to investigate this phenomenon, and test the hypothesis of plastic samples being tribocharged on contact with rapidly flowing solid CO2. Using Faraday pail measurements, we show that non-conductive polymers gain a net static charge when brought in and out of contact with dry ice (solid CO2). These measurements of charge sign and magnitude give indirect evidence helping to place solid CO2 for the first time on the triboelectric series. Polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), and polyvinyl chloride (PVC) samples acquire a negative charge when rubbed against dry ice, whereas poly(methyl methacrylate) (PMMA), glass, and nylon surfaces become positively charged. Therefore, we suggest the position of dry ice in the triboelectric series to be close to that of materials with stable cations and unstable anions, possibly locating it between PMMA and PVC.

Dynamic Mechanical Thermal Analysis of Wood Polymer Composite Endurance to Prolonged Ultra Violet Irradiation Exposure

This study was constructed to examine the viscoelastic properties and the microstructure of wood-plastic composites (WPCs) before and after being subjected to UV irradiation. The pellet of the wood polymer composites consists of polypropylene as the matrix and rice-husk flour as the reinforcing filler. The samples were UV irradiated from 5000 hours to 20,000 hours with the increment of 5000 hours to study the effect of weathering on the viscoelastic properties of the WPCs. The microstructures of the surface of the samples were examined using Optical Microscopy (OM). The mechanical properties of WPCs through dynamic mechanical analysis test were assessed for both polyvinyl chloride (PVC) and polypropylene (PP) samples. The value of storage modulus (E’) decreases when been exposed in the ultra violet irradiation, in both glassy and rubbery states. Moreover, the density of the WPC samples is closed to light weight and result is comparable. As for morphological properties test, the surface of cracked, voids appeared at the surface of the WPC samples of both PVC and PP interface and the density of composite decreased.