Dehydrochlorination Of Poly Research Articles

A useful method for thorough dehydrochlorination of Poly(vinylidene chloride-co-vinyl chloride) using Zinc(II) oxide

A poly(vinylidene chloride)-based polymer is a good material for food packaging as a barrier for oxygen and steam; however, there are problems related to chemical recycling due to low temperature degradation. To aid in developing a chemical recycling method without the evolution of harmful hydrochloric acid (HCl) and organochlorines, we have proposed a dehydrochlorination process at a low temperature (around 423 K) using zinc(II) oxide (ZnO). ZnO particles dispersed into the polymer matrix were found to be effective for thorough dehydrochlorination because the reaction promoters (zinc chloride [ZnCl2] and water) spontaneously penetrated the polymer via exothermic reactions. As a result, only a small percentage of chlorine atoms remained with a low amount of HCl. The efficiency of dehydrochlorination was a result of increasing the contact area with ZnO particles using a heat-kneading apparatus. The catalyst ZnCl2 was involved in the cross-linking reaction to form C–C single bond. Due to exothermic reaction, the scission or isomerization to polyene and aromatics also proceeded over a short period, leading to a microporous carbonaceous solid with a surface area of 5 × 102 m2/g.

Influence of External Conditions on the Relation between the Physical and Chemical Processes in the Thermodegradation of Plasticized Poly(Vinyl Chloride)

The heat-induced loss of plasticizer from and dehydrochlorination of poly(vinyl chloride) plasticized with dioctyl phthalate is studied by thermogravimetric analysis, IR spectroscopy, and colorimetry. Specific features and general regularities of the processes at high (200–320°C) and medium (100–132°C) temperatures are established. It is shown that the dehydrochlorination and oxidation processes dominate in confined space whereas, in unconfined space, plasticizer is lost largely through evaporation. The activation energies of the initial stages of the processes are determined.

Dehydrochlorination of poly(vinyl chloride) modified with titanium dioxide/poly(ethylene oxide) based paint photocatalysts

ABSTRACTThe dehydrochlorination of poly(vinyl chloride) (PVC) film samples modified with titanium dioxide (TiO2)/poly(ethylene oxide) (PEO) based paint photocatalysts [the addition of methyl linoleate (ML) or methyl oleate (MO)] was performed. After 24 h of UV photoirradiation, the sample with TiO2/PEO showed that there existed a structure with the longest polyene length, whereas that with TiO2/PEO/ML contained the most polyene structures. The chloroform‐soluble fraction of the sample with TiO2/PEO contained a poly(vinyl alcohol) (PVA) structure instead of a polyene one and showed a novel method of PVA production via PVC photodegradation. The molecular weight curve of the fraction shifted slightly to a lower molecular weight compared to that without the photocatalyst; this showed that slight polymer chain scission occurred. The 1H‐NMR and 13C‐NMR spectra showed that the content of PVA units was about 20%, and the PVA sequence was blocky. The fraction of the sample with TiO2/PEO/ML contained the highest methyl group content; this showed that the branch degree was highest as was the polyene content. These highest contents were due to the existence of the grafted ML. Pyrolysis gas chromatography/mass spectroscopy measurements suggested that there existed more polyene and graft units in the chloroform‐insoluble fractions of the samples with TiO2/PEO, TiO2/PEO/ML, and TiO2/PEO/MO, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40760.

Antioxidant properties of some 4-,6-methyl-substituted derivatives of isobornylphenol

Antioxidant properties of technical-grade mixtures containing 4, 6-methyl-substituted derivatives of isobornylphenol were studied. The antioxidant activity of samples was characterized by the inhibition rate constant kIn. The effect of isobornylphenol on the kinetics of inhibition of the thermooxidative dehydrochlorination of poly(vinyl chloride) plasticized with dioctyl phthalate was examined.

Preparation and characterization of flexible poly(vinyl chloride) foam films

In this study, the effect of activator ZnO and heating time at 190°C on foaming, gelation, and dehydrochlorination of poly(vinyl chloride) (PVC) plastisol was investigated. For this purpose, a PVC plastisol was prepared by mixing PVC, dioctyl phthalate (DOP), azodicarbonamide (ADC), ZnO, and the heat stabilizers calcium stearate (CaSt2) and zinc stearate(ZnSt2). PVC plastisol films were heated for 3, 6, 12, and 24 min periods at 190°C to see the effect of heating time on the gelation and foaming processes of the PVC foam. The time of 12 min was determined to be optimum for the completion of gelation and foaming processes without thermal degradation of PVC. No foaming was observed under the same conditions for the samples without ZnO. ZnO had a significant catalytic effect on ADC decomposition, accelerating the foaming of the films. Average porosity measurement showed a consistent increase in porosity with heating time up to 76% and the average density decreased from 1.17 to 0.29 g/cm3 on foaming. Tensile tests showed that the tensile strength and tensile strain both increased considerably up to 0.98 MPa and 207%, respectively, with heating time and the elastic modulus was seen to gradually decrease from 4.7 to 0.7 MPa with heating time. Films without ZnO had higher tensile strength since there were no pores. PVC thermomat tests showed that ZnO lowered the stability time of plastigel film with azodicarbonamide. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Dehydrochlorination of poly(vinyl chloride) with Ca(OH)2 in ethylene glycol and the effect of ball milling

The dehydrochlorination behavior of pure and flexible PVC in ethylene glycol was studied in the presence of Ca(OH)2 at temperatures between 170 °C and 190 °C. Although the dehydrochlorination proceeded slower in Ca(OH)2 than in NaOH, similar dehydrochlorination yields were obtained. It was assumed that the slower reaction rate was a result of the low solubility of Ca(OH)2 and the larger solvation shell of the Ca2+ ion. The dehydrochlorination rate and yield were improved by employing a ball mill. Additionally, diisononyl phthalate and CaCO3 were quantitatively separated from flexible PVC during the ball-milling process. The maximum dehydrochlorination yield of pure PVC after 7 h at 190 °C was 74%. After 8 h at the same temperature, a comparable dehydrochlorination yield of 77% was achieved for flexible PVC, which could be increased by ball milling to 86%.

Solid mechanochemical preparation of core‐shell SiO2 particles and their improvement on the mechanical properties of PVC composites

AbstractIn this article, a solid mechanochemical route to prepare core‐shell structured particles was introduced. X‐ray photoelectron spectrum, transmission electron microscope and dissolving experimental results indicated the formation of [(inorganic particle)/(elastomer)] core‐shell structured particles. The thermal stable experiments showed that untreated SiO2 can cause dehydrochlorination of poly(vinyl chloride) (PVC) and discoloration of PVC/SiO2 composites and the formation of core‐shell structured SiO2 particles will improve the thermal stability of PVC/SiO2 composites. The mechanical properties and rheological results showed that the formation of core‐shell structured SiO2 particles can both improve the mechanical and processing properties of PVC/SiO2 composite. ACR in PVC/(SiO2‐PMMA‐ACR) composites acted not only as toughener for PVC matrix but also as cushion breaker if the content of ACR is enough. Meanwhile compared with other SiO2 particles the formation of core‐shell structured SiO2 particles can decrease the apparent viscosity, increase the critical shear rate and improve the appearance of extrudes of PVC/SiO2 composites. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 938–948, 2008

Dehydrochlorination of poly(vinyl chloride) by microwave irradiation

Dehydrochlorination of poly(vinyl chloride) (PVC) by a commercial microwave oven has been studied. The results of decomposition and/or dehydrochlorination by microwave irradiation on PVC polymer and PVC resin wastes are summarized as follows: (1) the assist of microwave absorbent, such as activated carbon or ferrite, on decomposition and/or dehydrochlorination of PVC are effective, (2) the decomposition and/or dehydrochlorination yield is proportional to the irradiated microwave energy, (3) decomposition of PVC is mainly accounted for dehydrochlorination and during microwave irradiation, about 15% of volatilized organic materials are released from polymer, (4) on the commercial PVC resin wastes, more than 90% of dehydrochlorination yield are obtained by microwave irradiation.

Epoxide containing spherical beads from PVC

Dehydrochlorination of poly (vinylchloride) (PVC) bead particles (410-840 μm) has been performed by heating in liquid paraffin or pre-treatment with KOH-isopropanol and subsequent heating at 200 °C. These procedures give crosslinked dark-colored products with retention of the bead shapes. Catalytic epoxidation of the dehydrochlorinated products with t-butyl hydroperoxide yields gray-white to dark products with reasonable epoxide contents (1.7-4.7 mmol per gram). The method presented offers a simple pathway to prepare epoxidized spherical beads, starting from PVC. The resulting products are very useful as functional group carriers, due to high reactivity of the epoxy groups.

High-quality polyene prepared by liquid/solid two-phase dehydrochlorination of poly(vinyl chloride)

Polyvinyl chloride) (PVC) can be dehydrochlorinated extensively in a liquid/solid two-phase system by the catalyzation of poly(ethylene glycol) (PEG). The product, dehydrochlorinated poly(vinyl chloride) (DPVC), is polyacetylene-like and has the longest polyene sequences so far and a narrow dispersity of polyene sequences according to its FT-infrared and Raman spectra.

Thermodynamic properties of carbynoid structures in the 0-340 K range

The temperature dependences of the heat capacity (C p°) of carbynoid structures prepared by alkaline dehydrochlorination of poly(vinylidene chloride) and 1,1,2- and 1,2,3-polytrichlorobutadienes were studied by adiabatic vacuum calorimetry between 5 and 340 K with an accuracy of ∼0.2%. The low-temperature relaxation transitions and abnormal patterns of the C p° vs. T dependences were identified and characterized. The experimental results were used to calculate the thermodynamic functions C p°(T), H°(T) – H°(0), S°(T) – S°(0), and G°(T) – H°(0) for 0—340 K. These data were compared with the corresponding data for carbyne produced by oxidative dehydropolycondensation of acetylene, which is a mixture of amorphous α- and β-forms with a minor impurity of crystals of both forms.

Poly(ethylene glycol)s catalyzed two-phase dehydrochlorination of poly(vinyl chloride) with potassium hydroxide

Poly(ethylene glycol)s [HO(CH2CH2O)nH, where n > 3] are highly active and selective in catalyzing dehydrochlorination of poly(vinyl chloride) in organic–aqueous hydroxide two-phase systems. Their catalytic activity and stability are much higher than those of widely used quaternary ammonium or phosphonium compounds. Poly(vinyl chloride) can be extensively dehydrochlorinated within half an hour at room temperature. The products are polyacetylene-like and have long polyene sequences according to their UV/visible, FT-Raman, and FT-infrared spectra. They can be doped by iodine to conductive states, with conductivities of 1–4 S cm−1. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2463–2469, 1998

Formation of conjugated polyene and polyyne structure by KrF excimer laser-induced dehydrochlorination on polyvinylidenechloride film

The surface dehydrochlorination of poly(vinyldenchloride) film was performed to produce a conjugated polyyne and polyene structures by photo-irradiation with a KrF excimer laser at 248 nm in a vacuum chamber. The reaction was confirmed by detection of HCl with a mass spectrometer and by measurement of chlorine content on the film with X-ray photoelectron spectroscopy. UV-visible absorption spectroscopy for the laser-treated film showed the formation of new broad absorption bands in the visible and near IR region, indicating that sequential dehydrochlorination induced the formation of conjugated carbon multiple bonds in the polymer chain. Its conjugation number is estimated to be 30 for a triple bond and 10–25 for a double bond from the peak positions on the Raman spectrum of the film. ESR spectra of laser-irradiated PVDC powder also showed long-lived radicals having a narrow band width (ΔHpp = 0.15 mT), suggesting that the radicals were delocalized on the conjugated bonds. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2483–2487, 1998

New Mechanistic Aspects ofthe Dehydrochlorination of PVC - Application of Dehydrochlorination to Plastic Mixtures and Electronic Scrap

The dehydrochlorination of poly(vinyl chloride) is of interest from several points of view, e.g., the evolution of harmful substances during fires or waste incineration, reclaiming chemical raw materials from plastic waste, electronic scrap management and recycling of plastic waste mixtures. In this work some new mechanistic aspects of the decomposition of poly(vinyl chloride) are investigated by the combined application of TG-MS, isothermal experiments in a gradient-free reactor and DSC.Poly(vinyl chloride) degrades in two steps. At lower temperature (220-350°C) HCl and small amounts of benzene are formed. At higher temperature ( > 400°C) the residue decomposes into mostly aromatic compounds. Dehydrochlorination at moderate temperatures consists of an endothermic and exothermic path. The benzene formation is identified to be a second order reaction.The kinetic data for decomposition confirm that in mixtures of different plastics the dehydrochlorination of poly(vinyl chloride) can be conducted at moderate temperature and prior to the thermal degradation of most other plastics. This has been demonstrated in this work in a cascade of well stirred reactors at laboratory scale. The degree of conversion of chlorine from PVC into hydrogen chloride in the first reactor is about 99.6% at 330°C after a residence time of 26 min.Similar results are obtained during the thermal degradation of electronic scrap. The hydrogen chloride evolution from poly(vinyl chloride) occurs in the same way as in mixtures of commodity plastics. Brominated flame retardants are decomposed or evolve at higher temperatures ( > 300°C). The conversion of bromine into copper salts by means of copper from copper wires is observed as well.

The formation of diamond from carbynoid material at ambient pressure

Abstract Ultra-dispersed diamond (UDD) has been obtained by heating at the ambient pressure of carbynoid material, prepared by dehydrochlorination of poly(vinylidene chloride) in the presence of a small amount of UDD.

Fluorescent products from polyacetylene

Fluorescence excitation and emission spectra of a soluble product isolated from a preparation of polyacetylene are compared with those of polyene sequences formed by the chemical dehydrochlorination of poly(vinyl chloride) (PVC).

Chemical dehydrochlorination of polytrichlorobutadienes—A new route to carbynes

The chemical dehydrochlorination of polytrichlorobutadiene isomers, viz. poly(1,1,2-trichlorobutadiene) and poly(1,2,3-trichlorobutadiene) has been studied as a possible route to carbyne. The structure of the reaction products has been studied by IR, XPS, and Auger electron spectroscopy. The dehydrochlorination of poly(1,1,2- and 1,2,3-trichlorobutadiene) has been shown to result in the formation of the polyyne and cumulene forms of carbyne, respectively.

Effects of alkaline earth metal stearates on the dehydrochlorination of poly(vinyl chloride)

The thermo non-oxidative degradation of PVC and the effects of alkaline earth metal (Be, Mg, Ca, Ba) stearates were studied by thermogravimetry in the temperature range 150 to 500°C. The alkaline earth metal stearates were observed effectively reduce the dehydrochlorination of PVC. The synergistic effects of combinations of these salts with lead stearate were also studied and are discussed. Kinetic parameters such as the activation energy, order of reaction and Arrhenius factor were calculated by the Coats and Horowitz methods. The results showed that these metal stearates increase the activation energy required for the dehydrochlorination of PVC.

Raman Spectroscopic Study of the Interaction of Iodine with Polyene Sequences Derived from the Phase-Transfer-Catalyzed Dehydrochlorination of Poly(vinyl chloride)

Phase transfer catalysis has been shown to be an effective method for the dehydrochlorination of PVC to yield conjugated polyene sequences. The sequence lengths are not monodisperse; however, no very long sequences were detected by near-IR excited Raman spectroscopy. Doping the system with iodine gave an unusual material. Visible Raman spectra showed a slight decrease of conjugation length due to chain disruption, but the doped domains were generated with a short sequence length

Dehydrochlorination of Poly (vinyl chloride) in the Presence of Iron (III) Chloride Catalyst

Dehydrochlorination of Poly (vinyl chloride) in the Presence of Iron (III) Chloride Catalyst