The Influence of Additives on Crystallization of Polyvinyl Chloride

Acetanilide, adipic acid and potassium hydrogen phthalate were chosen as nucleating agents of polyvinyl chloride（PVC）, and their effects on PVC crystallization were studied by differential scanning calorimetry, wide angle X-ray diffraction and fourier transform infrared spectroscopy. The experimental results indicate that all of the three additives are compatible with PVC to some extent, but adipic acid＇s compatibility with PVC is less satisfactory. The three additives can improve PVC crystallinity, and acetanilide can decrease PVC glass transition temperature（T）and narrow PVC melting range, while adipic acid and potassium hydrogen phthalate rise T of PVC and widen its melting range. All additives do not affect PVC crystal system and all g samples are in orthorhombic system. All additives can improve （200）, （110）, （210） and （201, 111） planes growing. Moreover, acetanilide and adipic acid can shrink PVC spacings and improve the crystal perfection of PVC, but potassium hydrogen phthalate swells spacings and reduces the perfection of PVC crystal.

Surface Sulfonation of Polyvinyl Chloride by Plasma for Antithrombogenicity

To enhance the blood compatibility of Polyvinyl Chloride (PVC) film, the film was modified by SO2/O2 gas plasma treatment. The effect of surface sulfonation of PVC treated by various SO2/O2 gas plasma depended on the volume ratio O2/(SO2 +O2). When the volume ratio was 0.5, the effect of sulfonation was the best. Sulfonic acid groups were specifically and efficiently introduced onto the PVC surface, which was proved by X-ray photoelectron spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transfer Infrared (ATR-FTIR) spectroscopy. The surface microstructure of modified PVC film was studied with scanning electron microscopy (SEM). The antithrombogenicity of the samples was determined by the activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) and plasma recalcification time (PRT) tests and platelet adhesion experiment. The results indicated that the antithrombogenicity of modified PVC was improved remarkably.

Thermogravimetric characteristics and different kinetic models for medical waste composition containing polyvinyl chloride-transfusion tube

Thermogravimetric study of medical transfusion tube （MTT） waste containing polyvinyl chloride （PVC） was carried out using the thermogravimetric analyser （TGA） with N2, at different heating rates of 5, 10, 20, 30, 50 ℃/min. The purpose is to obtain pyrolysis characteristics and kinetic parameters of medical waste. The experimental results indicate that the pyrolysis behavior of the MTT sample is in agreement with its main ingredient of PVC, appearing two stair stepping stages. The influence of the additives in MTT on pyrolysis behavior was also revealed, which could improve MTT pyrolysis at lower temperature in the first stage, and cause obvious unsmoothness and asymmetry of the second DTG peak. Four n-order kinetic models of Coats-Redfern, Ozawa, Kissinger and Freeman-carroll were used to get the kinetic parameters. Furthermore, a novel ＂two-step four-reaction model＂ was established to simulate the whole continuous process. The different methods and the kinetic parameters thus obtained were discussed and compared with each other in literatures. The reasons of deviation among kinetic values were tried to be elucidated. The new established model could more satisfactorily describe the pyrolysis process of MTT, being more mechanistic and conveniently serving for the engineering.

Compressive Performance of Fiber Reinforced Recycled Aggregate Concrete by Basalt Fiber Reinforced Polymer-Polyvinyl Chloride Composite Jackets

The development of recycled aggregate concrete(RAC)provides a new approach to limiting the waste of natural resources.In the present study,the mechanical properties and deformability of RACs were improved by adding basalt fibers(BFs)and using external restraints,such as a fiber-reinforced polymer(FRP)jacket or a PVC pipe.Samples were tested under axial compression.The results showed that RAC(50%replacement of aggregate)containing 0.2%BFs had the best mechanical properties.Using either BFs or PVC reinforcement had a slight effect on the loadbearing capacity and mode of failure.With different levels of BFs,the compressive strengths of the specimens reinforced with 1-layer and 3-layer basalt fiber reinforced polymer(BFRP)increased by 6.7%–10.5%and 16.5%–23.7%,respectively,and the ultimate strains increased by 48.5%–80.7%and 97.1%–141.1%,respectively.The peak stress of the 3-layer BFRP-PVC increased by 42.2%,and the ultimate strain improved by 131.3%,relative to the control.This reinforcement combined the high tensile strength of BFRP,which improved the post-peak behavior,and PVC,which enhanced the structural durability.In addition,to investigate the influence of the various constraints on compressive behavior,the stress-strain response was analyzed.Based on the analysis of experimental results,a peak stress-strain model and an amended ultimate stress-strain model were proposed.The models were verified as well;the result showed that the predictions from calculations are generally consistent with the experimental data(error within 10%).The results of this study provide a theoretical basis and reference for future applications of fiber-reinforced recycled concrete.

SYNERGISTIC MODIFICATION OF EPDM AND CROSSLINKING AGENT IN IMMISCIBLE BLENDS OF POLYVINYL CHLORIDE WITH LOW DENSITY POLYETHYLENE

The synergism of ethylene-propylene-diene monomer copolymer （EPDM） and dicumyl peroxide （DCP, a crosslinking agent） in low density polyethylene （LDPE）/poly（vinyl chloride） （PVC） blends was investigated. When EDPM and DCP are added to the blends simultaneously, the tensile properties could be improved significantly, especially for the blends with LDPE matrix. For example, incorporation of 10/1 （mass ratio） EPDM/DCP improves the tensile strength of the LDPE/PVC （mass ratio 80/20） blend from 7.9 MPa to 8.5 MPa and the elongation at break from 25% to 503%. Results from selective extraction, phase-contrast microscopy and thermal analysis reveal that the improvement in the tensile properties of the blends with LDPE matrix is principally due to the formation of a fine crosslinking network of the LDPE and EPDM phase. The outstanding modification effect of EPDM is explained by its dual functions： molecular entanglement with LDPE and the enhanced efficiency of DCP in the blends.

Molecular Dynamics Simulation Studies on the Cooling Process of Polyvinyl Chloride

By means of molecular dynamics simulation, the transition of the conformations of polyvinyl chloride during a cooling process from 600 to 300 K was studied. The results show that the amorphous polyvinyl chloride chain experiences the melting state, elastic state and glass state and the conformations can be characterized by the increases of the trans-state of C--C--C--C and the near gauche-state of C--C--C--C1 with the decrease of temperature. It is found that the transition of the conformations is driven mainly by the Coulomb interaction between chain segments.

STUDY ON THE MORPHOLOGY OF POLYVINYL CHLORIDE/POLYSTYRENE BLENDS BY ELECTRON MICROPROBE ANALYSIS

The morphology of polyvinyl chloride/polystyrene (PVC/PS) blend samples with different mass ratios, prepared by means of solution casting and melt mixing, have been successfully examined by electron microprobe analysis (EMP). This experiment was performed in a scanning electron microscope attached to an energy dispersive X-ray analyzer. Differential scanning calorimetry was also used to investigate the phase separation of the blends. The results show that PVC and PS are incompatible and the blends have sea-islands phase structures. Blends prepared via melt mixing have finer phase-dispersion than those prepared via solution casting.

Phosphorus Containing Rubber Seed oil as a Flame Retardant Plasticizer for Polyvinyl Chloride

The application of phthalate plasticizers has been restricted around the world due to their poor migration and potential harm to the human body.Hence,producing functional bio-based plasticizers via exploiting clean and reusable resources meets the satisfaction of current demands.In this study,flame-retardant rubber seed oil-based plasticize(FRP)was prepared via epoxidation reaction and ring opening addition reactions,which was used as a flame-resistant plasticizer for polyvinyl chloride to replace petroleum-based phthalate plasticizer.When DOP was replaced with FRP,the torque of PVC blends increased from 11.4 to 18.4 N⋅m,the LOI value increased from 24.3%for PVC-FRP-0%to 33.1%for PVC-FRP-20.The THR value diminished from 39 MJ/m^(2)(pertaining to PVC-FRC-0)to 22 MJ/m^(2)Tg increased from 23°C to 47°C,the weight loss of plasticized PVC blends significantly reduced from 22.6%to 2.8%in leaching tests.The study provided a new way to prepare flame retardant plasticizer using rubber seed oil as raw material.

Linear extrapolation for prediction of tensile creep compliance of polyvinyl chloride

The universal creep equation is successful in relating the creep （ε） to the aging time （t） , coefficient of retardation time （β） , and intrinsic time （ to ）. This relation was used to treat the creep experimental data for polyvinyl chloride （ PVC ） specimens at a given stress and different aging times. The βgs found by the “polynomial fitting” method in this work instead of the “middle - point” method reported in the literature. The unified master line was constructed with the treated data and curves according to the universal equation. The master line can be used to predict the long- term creed behavior and lifetime by extrapolating.

Synthesis of lanthanum tris (mono-i-octyl phthalate) and its thermal stability for polyvinyl chloride

A novel type of thermal stabilizer-lanthanum tris (mono- i -octyl phthalate) (LTMP) was synthesized by double-decomposition reaction o f sodium mono- i -octyl phthalate with lanthanum chloride at 60 ℃. Sodium m ono- i -octyl phthalate was prepared by sodium hydrate and mono- i -octy l phthalate prepared by reaction of isooctyl alcohol and phthalic anhydride in th e presence of sulfuric acid catalyst at 110 ℃. The yield of lanthanum tris (mon o- i -octyl phthalate) is about 84.5%. Its thermal stabilities were measured by heat-ageing oven test when incorporated into PVC. The experimental results show that the heat stability time is about 40min at 190 ℃ when adding 3phr (pe r hundred resin) to PVC. The thermal stability of this product is better than th at of Ca-Zn complex and basic lead salt stabilizers, and equal to that of dibut yltin dilaurate.

Preparation and Properties of Polyvinyl Chloride/Carbon Nanotubes Composite

Chemically functionalized carbon nanotubes were combined with PVC to enhance both toughness and strength by simply mixing long alkyl chain modified multi-wall carbon nanotubes (abbreviated as MWNTs) or Ester-functionalized soluble MWNTs (abbreviated as eMWNTs) with PVC in Tetrahydrofuran (THF)/Cyclohexanone (CH) solution to obtain good dispersity solution. The MWNTs modified with 1-Bromohexadecane can effectively increase the intermolecular force with PVC by hydrogen bond. The obtained nanocomposite has a regular shape with homogeneously dispersed particles. PVC/2 wt% eMWNTs has been proved to possess excellent thermal stability. The intermolecular force between eMWNTs and PVC endows the as-fabricated nanocomposite with enhanced toughness and strength, indicating that our method is promising for wide use in PVC/eMWNTs nanocomposition.

Electro-reductive carboxylation of C–Cl bonds in unactivated alkyl chlorides and polyvinyl chloride with CO_(2)

The carboxylation of readily available organo halides with CO_(2)represents a practical strategy to afford valuable carboxylic acids.However,efficient carboxylation of inexpensive unactivated alkyl chlorides is still underdeveloped.Herein,we report the electro-reductive carboxylation of C–Cl bonds in unactivated chlorides and polyvinyl chloride with CO_(2).A variety of alkyl carboxylic acids are obtained in moderate to good yields under mild conditions with high chemoselectivity.Importantly,the utility of this electroreductive carboxylation is demonstrated with great potential in polyvinyl chloride(PVC)upgrading,which could convert discarded PVC from hydrophobic to hydrophilic functional products.Mechanistic experiments support the successive single electron reduction of unactivated chlorides to generate alkyl anion species and following nucleophilic attack on CO_(2)to give desired products.

Poisoning effect of polyvinyl chloride on the catalytic pyrolysis of mixed plastics over zeolites

Nowadays,the chemical recycling is applied for only 1%of total waste plastics,largely due to contaminants in plastic waste and difficulty in product control.As the major contaminant,polyvinyl chloride(PVC)often forms corrosive hydrogen chloride(HCl)during the chemical recycling,which may cause severe catalyst deactivation and equipment damage.However,the investigation on catalytic pyrolysis(the major route for plastics chemical recycling)of the PVC containing mixed plastics has been rarely reported.Here,catalytic co-pyrolysis of PVC and polyethylene(PE)was studied over an aromatization catalyst,Pt/ZSM-5,since the basic building block aromatics are desired products from plastics chemical recycling.The poisoning effect of PVC vapor on the catalyst stability was explored by collective efforts of thorough product analysis and catalyst characterization.It was found that the HCl evolving from PVC has an autocatalytic effect that promotes the scission of dehydrochlorinated PVC,resulting in the high yield of benzene and acetylene from PVC.On the other hand,the presence of PVC suppressed the aromatics formation from PE,largely due to the poisoning effect of PVC-derived HCl on the Pt/ZSM-5.The deactivation is irreversible as evidenced by the decreased zeolite crystallinity and the loss of strong acid sites that are key to the aromatization,possibly due to the removal of framework Al upon the interaction with HCl.The modification with octadecylphosphonic acid only slightly alleviated the PVC poisoning effect.The insights on the PVC poisoning of zeolite catalysts provided in this work may guide the process design of chemical recycling of PVC containing waste plastics.

Toxicity mechanisms of photodegraded polyvinyl chloride nanoplastics on pea seedlings

Nanoplasctics(NPs),which are very small in particle size,exert toxic effect to organisms.Additionally,compared to original NPs,photodegraded NPs would pose higher toxicity.This is because their relatively higher specific surface areas and the presence of additives which can more easily leach.How original NPs and aged NPs affect plant growth has not been widely investigated.This work chose polyvinyl chloride NPs(PVC-NPs)that were subjected to up to 1000 h UV light radiation to explore the impact of PVC-NPs on the growth of pea seedlings(Pisum Sativum L.).The results indicated the existence of PVC-NPs with longer UV light radiation time and higher concentrations had more negative influences on pea seedlings’growth such as germination rate(decreased by 10.6%–22.5%),stem length(decreased by 2.8%–8.1%),dry weight(decreased by 6.3%–7.1%)and fresh weight(decreased by 6.7%–14.8%).It was also noted that photodegraded PVC-NPs resulted in damage to leaf stomata and roots,hindering photosynthesis and absorption of nutrients and hence the decrease in chlorophyll and soluble sugar contents.According to transcriptomic investigation results,the presence of aged PVC-NPs primarily influenced protein processing in endoplasmic reticulum(upregulated metabolic pathway)and phenylpropanoid biosynthesis(downregulated metabolic pathway)of pea seedlings.These results provide an in-depth understanding of how NPs influence the growth of plants.

EFFECT OF POLYANILINE AS A SURFACE MODIFIER OF TiO_2 NANO-PARTICLES ON THE PROPERTIES OF POLYVINYL CHLORIDE/TiO_2 NANOCOMPOSITES

Surface of TiO2 nanoparticles was modified with the in situ chemical oxidative polymerization of aniline. Polyaniline modified TiO2 nanoparticles （PANI-TiO2） were characterized with the FT-IR, XRD, SEM and TEM techniques. Results confirmed that PANI was grafted successfully on the surface of TiO2 nanoparticles, therefore agglomeration of nanoparticles decreased dramatically. Polyvinyl chloride nanocomposites filled with 1 wt%-5 wt% of PANI-TiO2 and TiO2 nanoparticles were prepared via the solution blending method. PVC nanocomposites were analyzed with FT-IR, XRD, SEM, TG/DTA, DSC and tensile test techniques. Effect of PANI as surface modifier of nanoparticles was discussed according to the final properties of PVC nanocomposites. Results demonstrated that deposition of PANI on the surface of TiO2 nanoparticles improved the interfacial adhesion between the constituents of nanocomposites, which resulted in better dispersion of nanoparticles in the PVC matrix. Also PVC/PANI-TiO2 nanocomposites showed higher thennal resistance, tensile strength and Young＇s modulus compared to those of unfilled PVC and PVC/TiO2 nanocomposites.

Preparation of a Crosslinked Chitosan Coated Calcium Sulfate Whisker and Its Reinforcement in Polyvinyl Chloride

A calcium sulfate whisker （CSW） coated with glutaraldehyde crosslinked chitosan （GACS） was prepared to reinforce polyvinyl chloride （PVC） in this study. The results show that the optimum concentration of both chitosan （CS） and glutaraldehyde （GA） is 0.05 wt%. The tensile strength, impact strength, flexural modulus and vicat softening temperature of the PVC composite with 12 wt% of modified CSW are in- creased by 1 Z5%, 40.4%, 0.8% and 3.8% compared with those of the PVC composite with 12 wt~ of unmodified CSW, and by 2.9%, 42.4%, 2Z1% and 6.8% compared with those of pure PVC, respectively. The dynamic mechanical analysis results indicate that the modified CSW/PVC composite exhibits much higher storage modulus and glass transition temperature than those of unmodified CSW/PVC composite and pure PVC. In addition, the modified CSW/PVC composite also demonstrates good thermal properties with a high rapidest decomposition temperature （Trvd） and char residue. The scanning electron microscopy images of tensile-fractured surfaces show that the modified CSW has a strong interfacial adhesion with PVC matrix.

Enhancement of Photocatalytic Degradation of Polyvinyl Chloride Plastic with Fe_(2)O_(3) Modified AgNbO_(3) Photocatalyst under Visible-light Irradiation

The solid-phase photocataKtic degradation of polyvinyl chloride(PVC)plastic with AgNbO_(3)/Fe_(2)O_(3) is studied under visible-light irradiation.The PVC-(AgNbO_(3)/Fe_(2)O_(3))samples are characterized by X-ray photoelectron spectroscope(XPS),scanning electron microscope(SEM),gas chromatography(GC),and UV-vis diffusion reflectance spectra(UV-vis DRS).The photocatalytic properties of PVC-(AgNbO_(3)/Fe_(2)O_(3))samples are systematically investigated.More amounts of generated CO2,greater texture change and higher weight loss rate were exhibited in the system of PVC-(AgNbO_(3)/Fe_(2)O_(3))than pure PVC film.The weight loss rate is ten times higher than that of pure PVC film,which reaches to 46.53%with optimum amount of O.5wt% Fe_(2)O_(3).Active radicals generate primarily on the surface of Fe_(2)O_(3) particles,which cause composite plastic decomposition on the PVC-(AgNbO_(3)/Fe_(2)O_(3))interface and extend into polymer interor.The study provides a new promising way to degrade the plastic waste under visible-light.

Comparative study on the efficiency and environmental impact of two methods of utilizing polyvinyl chloride waste based on life cycle assessments

Two processes of utilizing polyvinyl chloride （PVC） waste, an incineration process and a vacuum pyrolysis process, for energy conversion were compared to determine their efficiency and environmental perfor- mance. We carried out a life cycle assessment with each of the two processes to evaluate their environmental impact and defined the goals and limits of our remit. As well, we established an inventory of PVC waste from incineration and vacuum pyrolysis based on process analysis, data collection and calculations. The results show that electrical power output per unit mass of PVC waste in the incineration process was twice as high as that of the vacuum pyrolysis process. Incineration had a larger total environmental impact potential than vacuum pyrolysis. The total environmental impact potential of PVC waste from incineration was three times higher than that from vacuum pyrolysis. Incineration of PVC disposed 300 ng. 100 kgI of dioxins and vacuum pyrolysis 98.19 ng- 100 kgI of dioxins. As well, we analyzed the data for their uncertainty with results quantified in terms of three uncertainties： basic uncertainty, additional uncertainty, and computational uncertainty. The coefficients of variation of the data were less than 25% and the quality of the inventory data was acceptable with low uncertainty. Both PVC waste disposal processes were of similar quality and their results comparable. The results of our life cycle impact assessment （LCIA） showed considerable reliability of our methodology. Overall, the vacuum pyrolysis process has a number advantages and greater potential for development of PVC disposal than the incineration process.

INFLUENCE OF LANTHANUM STEARATE AND CALCIUM/ZINC STABILIZERS ON STABILIZATION EFFICIENCY OF DIBUTYLTIN DILAURATE TO POLYVINYL CHLORIDE

Influences of lanthanum stearate （LaSt3） and calcium stearate/zinc stearate （Ca/Zn） stabilizers on stabilization efficiency of dibutyltin dilaurate （DBTDL） to polyvinyl chloride （PVC） in air were investigated. The results revealed that the stabilization effect of DBTDL could be achieved by the La/Sn stabilizers with a ratio of 8/2. Addition of DBTDL could enhance thermal property and reduce dynamic storage modulus （G＇） at 180℃ for PVC containing LaSt3 or Ca/Zn stabilizers. On the other hand, incorporation of LaSh did not influence the stabilization efficiency of DBTDL markedly; while addition of Ca/Zn stabilizers could significantly decrease thermal property for the DBTDL stabilized PVC. Furthermore, the effects of LaSt3 and Ca/Zn stabilizers on the stabilization efficiency of DBTDL were explained in the framework of ionization potential.

Gasification kinetics of char formed from waste polyvinyl chloride for efficient utilization in ironmaking process

In the prevailing incineration processes of municipal solid waste,the presence of polyvinyl chloride(PVC)may cause environmental problems.The energy-intensive ironmaking sector in the iron and steel industry operates at high temperature and under high reduction potential with the function of energy conversion,which can provide a potential path for the collaborative utilization of waste plastics in large quantities and low cost.The gasification of the char formed from PVC when processed in the ironmaking sector is significant for the development of the related technologies.Thus,the gasification experiment of PVC char and traditional carbonaceous materials was performed by thermogravimetric analysis.The results indicated that the gasification ability decreased in the sequence of PVC char>anthracite coal>coke>graphite.Then,kinetics were also analyzed by Coats-Redfern and Doyle approximations.The PVC char showed the best gasification ability with the smallest activation energy,ranging from 87.18 to 117.52 kJ/mol,and the smaller graphitization degree of PVC char compared with other carbonaceous materials should be the main reason for its excellent gasification reactivity.