Analysis of degradation mechanism of plasticized PVC under artificial aging conditions

A plasticized poly(vinyl chloride) (PVC) has the advantage of low cost, long-term stability and flame resistance among other commodity plastic, and has been in service as a product in railway field. However, the transition of the plasticizer concentration through the degrading condition and its relationship with the mechanical properties, the molecular motion, the appearance of surface and other properties was not clear. These relationships were studied by means of Rheovibron, pulse NMR, GC/MS, GPC, SEM and other methods. The bulk properties show similar change between weathering and thermal aging. In addition, the molecular chain was little influenced, however, the plasticizer concentration shows obviously different transition through each phase of aging conditions. According to the results of the observation of surface and section, different appearances between weathering and thermal aging were indicated and these appearances closely relate to the bulk properties. In conclusion, through the weathering condition, a stepwise flow out of inorganic components and plasticizer was presumable to be a main mechanism of the degradation. On the other hand, through the thermal aging condition, the rearrangement and aggregation of the molecular chain by the annealing effect were conceivable as the main mechanism of the degradation.     

Antimicrobial,mechanical, optical and thermal properties of PVC/ZnO‐EDTA nanocomposite films

Covalent surface functionalization of synthesized ZnO nanoparticles (NP)s with ethylenediaminetetraacetic acid (EDTA) was successfully carried out. Modified ZnO‐EDTA NPs as a viable and inexpensive filler were incorporated into poly(vinyl chloride) PVC matrix after their chemical modification to investigate the agglomeration behavior. All prepared materials including modified NPs and PVC/ZnO‐EDTA nanocomposites (NC)s were analyzed by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, X‐ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. Fabricated PVC/ZnO‐EDTA NCs were reported to have high transparency and improved mechanical properties compared with PVC. Modified ZnO and the fabricated NCs were shown to exhibit excellent antibacterial activity against two bacteria species: Escherichia coli and Staphylococcus aureus. The obtained NCs could be considered as self‐extinguishing materials on the basis of the LOI values. Copyright © 2016 John Wiley & Sons, Ltd.     

FT‐IR Investigation into the miscible interactions in new materials for optical devices

In this article we determine the miscibility of azobenzene derivative (poly(4‐(N‐(2‐methacryloyloxyethyl)‐N‐ethylamino)‐4′‐nitroazobenzene)₉₀‐co‐(methyl methacrylate)₁₀)/poly(vinyl acetate) (PVAc) and azobenzene derivative/poly(vinyl chloride) (PVC) blends using Fourier Transform infrared (FT‐IR) spectroscopy. With this method we can clearly identify the exact interactions responsible for miscibility. In the azobenzene derivative 50:50PVAc blend new peaks were evident at 2960, 2890, 1237 and 959 cm^?1, these peaks depict miscible interactions. These wavenumbers indicate that the miscible interactions occurring are from the C? H stretching band, the vinyl acetate C?O, conjugated to the ester carbonyl, the cis‐transformation N?N stretch frequency and the acetate ester weak doublet. The azobenzene derivative 80:20PVC blend display peaks identical in profile to the blend homopolymers, indicating no miscible interactions. However, this could be due to overlapping of peaks within the same wavenumber region, making resolution difficult. This research demonstrates FT‐IR can deduce favorable interactions for miscibility and therefore numerous miscible blends can successfully be calculated if possessing the same groups responsible for miscibility. This paves the way for a new generation of designer optical materials with the desired properties. Copyright © 2003 John Wiley & Sons, Ltd.     

稀土掺杂PVC的紫外及微波交联研究

聚氯乙烯 (ＰＶＣ)是我国目前产量最大 ,应用面最广的高分子原材料。但其耐热性、稳定性及抗老化性都较差。我们考虑到使用稀土掺杂以改进其相关性能 ,同时掺入了少量从水玻璃中提取出来的活性硅醇到ＰＶＣ中以增加其柔性 ,探索了紫外辐射交联和微波辐射交联对ＰＶＣ机械力学性能的影响。本文采用ＰＶＣ流延膜来进行辐射交联并测定样品的力学性能。结果发现 ,稀土掺杂的结果使得样品的扯断伸长率大幅度提高 ,拉伸强度上升显著。而添加活性硅醇后ＰＶＣ流延膜的扯断伸长率进一步提高 ,拉伸强度则下降 ,柔性得以提高。将氯化钕溶于 95 %的乙醇…     

Application of a bio‐based polyester plasticizer modified by hydrosilicon‐hydrogenation reaction in soft PVC films

A kind of bio‐based plasticizer, poly (hexanediol maleic) (MH), was synthesized using 1,6‐hexalene and maleic acid as raw materials, and it was modified by hydrosilicon‐hydrogenation reaction to improve its plasticizing efficiency. The chemical structure and plasticizing performance of MH and its modification product (MHA) were characterized by Fourier‐transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H‐NMR), X‐ray photoelectron spectroscopy (XPS), and Dynamic mechanical analysis (DMA). It was found that the hydrosilicon‐hydrogenation modification effectively improved the plasticizing efficiency of MH, reflecting on the decreased T_g and the increased elongation at break of PVC blends. The migration resistance of PVC blends was tested and analyzed by solubility parameters, which revealed that the migration stabilities of PVC blends were promoted after modification. It was verified that the hydrogen bonding interaction between the C?O group of plasticizers and α‐hydrogen of PVC exhibited in FTIR analysis was the main reason for the improvement of plasticizer performance of MH. Moreover, a new hydrogen bonding formed between Si? O? Si of MHA and the α‐hydrogen of PVC derived from XPS also caused the further improvement of plasticity for MHA.     

Effects of Epoxidation Content of ENR on Morphology and Mechanical Properties of Natural Rubber Blended PVC

This research work has concerned a study on toughness of PVC/natural rubber (NR) blends compatibilized with epoxidized natural rubber (ENR). The aim of this work was to investigate the effect of degree of epoxidation on morphology and mechanical properties of the blends. Epoxidized natural rubber with a variety of epoxidation contents were prepared by reacting the NR latex with formic acid and hydrogen peroxide at various chemical contents. Chemical structure and epoxidation content of epoxidized natural rubber were evaluated by FTIR and ¹H-NMR techniques. After that, three grades of ENR with epoxidation contents of 15, 25 and 42 % (by mole) were further used for blending with PVC and NR in an internal mixer at 60 rpm and at 170 °C. From tensile and impact tests, it was found that tensile elongation and impact strength of the materials remarkably increased with degree of epoxidation. On the other hand, tensile strength and modulus of the materials rarely changed with the epoxidation content. An increase in toughness of the blends with epoxidation content was related to a better molecular interaction between PVC and ENR as suggested by torque-time curves of the materials.     

Radiation effects on the thermal degradation of poly(vinyl chloride) and poly(vinyl alcohol)

Radiation effects on the formation of conjugated double bonds in the thermal degradation of poly(vinyl chloride) (PVC) and poly(vinyl alcohol) (PVA) were investigated. Thin films of PVC and PVA were either irradiated with γ-rays at ambient temperature (pre-irradiation) and then subjected to thermal treatment, or irradiated at elevated temperatures (in situ irradiation). An extensive enhancement of the thermal degradation was observed for the pre-irradiation of the PVC films, which was more effective than the effect of the in situ irradiation at the same absorption dose. For the PVA degradation, however, the effect of the in situ irradiation was larger than that of the pre-irradiation. The results were explained and related mechanisms were discussed based on radiation-induced chemical reactions and their individual contributions to the thermal degradation behaviors of the two polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3089–3095, 1998     

Synthesis of α,ω‐di(iodo)PVC and of four‐arm star PVC with identical active chain ends by SET‐DTLRP of VC initiated with bifunctional and tetrafunctional initiators

Na₂S₂O₄‐catalyzed single‐electron transfer – degenerative chain transfer‐mediated living radical polymerization (SET‐DTLRP) of VC initiated with the bifunctional initiators 1,2‐bis(iodopropionyloxy)ethane, dimethyl 2,5‐diiodohexanedioate, and bis(2‐methoxyethyl)‐2,5‐diiodohexanedioate as well as the tetrafunctional initiator pentaerythritol tetrakis(2‐iodopropionate) is reported. This SET‐DTLRP was performed in water at ambient temperature in the presence of polyvinyl alcohol and hydroxypropyl methylcellulose surfactants and provides methods for the synthesis of α,ω‐di(iodo)PVC with two identical active chain ends and of four‐arm star PVC with four identical active chain ends. These difunctional and tetrafunctional derivatives of PVC are also macroinitiators for the synthesis of ABA triblock copolymers and four‐arm star block copolymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 635–652, 2009     

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

In 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     

Ring‐opening metathesis polymerization as a route to controlled copolymers of ethylene and polar monomers: Synthesis of ethylene–vinyl chloride‐like copolymers

A series of ethylene–vinyl chloride‐like copolymers were prepared by ring‐opening metathesis polymerization (ROMP). The route to these materials included the bulk polymerization of 5‐chlorocyclooctene and 5,6‐dichlorocyclooctene with the first‐generation Grubbs' catalyst, followed by diimide hydrogenation of the resulting unsaturated polymers. In addition, the amount of chlorine in these materials was varied by the copolymerization of 5‐chlorocyclooctene with cyclooctene. These materials were fully characterized by NMR (¹H and ¹³C), gel permeation chromatography, and Fourier transform infrared spectroscopy. Finally, hydroboration was carried out on the ROMP product of 5‐chlorocyclooctene to yield a polymer, which was effectively a vinyl alcohol–vinyl chloride–ethylene terpolymer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2107–2116, 2003     

Overview of the recent literature on flame retardancy and smoke suppression in PVC

This paper presents an overview of the recent literature on flame retardancy of poly(vinyl chloride) (PVC). A short overview of mechanisms of thermal decomposition of PVC, especially those which lead to char formation, is also presented because this gives insight into the mechanisms of flame retardant action. New developments in the area are mostly focused on combinations of various flame retardants and smoke suppressants in the search for synergistic effects. Because different additives show different mechanisms of action, synergistic combinations are very probable. New developments in phosphate ester plasticizers are reported in the literature. Copyright © 2005 John Wiley & Sons, Ltd.     

Terpyridine‐modified poly(vinyl chloride): Possibilities for supramolecular grafting and crosslinking

Commercially available poly(vinyl chloride) (PVC) was covalently modified with terpyridine supramolecular binding units in a two‐step reaction. First, PVC was modified with aromatic thiols to introduce OH functionalities into the polymer backbone, which were subsequently reacted with an isocyanate‐functionalized terpyridine binding unit. The resulting functionalized material contained metal‐ion binding sites, which could be used for grafting and crosslinking reactions. A grafting experiment was performed with a small organic terpyridine ligand. The complexation of the modified PVC with several transition‐metal ions was studied with ultraviolet–visible spectroscopy and gel permeation chromatography. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2964–2973, 2003     

Covalently Linked Plasticizers: Triazole Analogues of Phthalate Plasticizers Prepared by Mild Copper‐Free “Click” Reactions with Azide‐Functionalized PVC

Copper‐free azide‐alkyne click chemistry is utilized to covalently modify polyvinyl chloride (PVC). Phthalate plasticizer mimics di(2‐ethylhexyl)‐1H‐triazole‐4,5 dicarboxylate (DEHT), di(n‐butyl)‐1H‐1,2,3‐triazole‐4,5‐dicarboxylate (DBT), and dimethyl‐1H‐triazole‐4,5‐dicarboxylate (DMT) are covalently attached to PVC. DEHT, DBT, and DMT have similar chemical structures to traditional plasticizers di(2‐ethylhexyl) phthalate (DEHP), di(n‐butyl) phthalate (DBP), and dimethyl phthalate (DMP), but pose no danger of leaching from the polymer matrix and forming small endocrine disrupting chemicals. The synthesis of these covalent plasticizers is expected to be scalable, providing a viable alternative to the use of phthalates, thus mitigating dangers to human health and the environment.

     

From metal‐catalyzed radical telomerization to metal‐catalyzed radical polymerization of vinyl chloride: Toward living radical polymerization of vinyl chloride

The metal‐catalyzed radical polymerization of vinyl chloride (VC) in ortho‐dichlorobenzene initiated with various activated halides, such as α,α‐dihaloalkanes, α,α,α‐trihaloalkanes, perfloroalkyl halides, benzyl halides, pseudohalides, allyl halides, sulfonyl halides, α‐haloesters, α‐halonitriles, and imidyl halides, in the presence of Cu(0)/2,2′‐bipyridine, Fe(0)/o‐phenantroline, TiCp₂Cl₂, and other metal catalysts is reported. The formation of the monoadduct between the initiator and VC was achieved with all catalysts. However, propagation was observed only for metals in their zero oxidation state because they were able to reinitiate from geminal dihalo or allylic chloride structures. Poly(vinyl chloride) with molecular weights larger then the theoretical limit allowed by chain transfer to VC were obtained even at 130 °C. In addition, the most elemental features of a living radical polymerization, such as a linear dependence of the molecular weight and a decrease of polydispersity with conversion, were observed for the most promising systems based on iodine‐containing initiators and Cu(0), that is, I? CH₂? Ph? CH₂? I/Cu(0)/bpy (where bpy = 2,2′‐bipyridyl), at 130 °C. However, because of the formation of inactive species via chain transfer to VC and other side reactions, the observed conversions were in most cases lower than 40%. A mechanistic interpretation of the chain transfer to monomer in the presence of Cu species is proposed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3392–3418, 2001     

Functionalization of the active chain ends of poly(vinyl chloride) obtained by single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization: Synthesis of telechelic α,ω‐di(hydroxy)poly(vinyl chloride)

The chloroiodomethyl chain ends of poly(vinyl chloride) (PVC) obtained by the single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization of vinyl chloride initiated with iodoform were quantitatively functionalized by the reaction with 2‐allyloxyethanol (CH₂?CHCH₂OCH₂CH₂OH). This reaction was performed in dimethyl sulfoxide at 70 °C and was catalyzed by sodium dithionite/sodium bicarbonate. The resulting product is the first example of telechelic PVC [α,ω‐di(hydroxy)PVC]. A possible mechanism for this reaction was suggested. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1255–1260, 2005     

SET‐LRP of vinyl chloride initiated with CHBr3 and catalyzed by Cu(0)‐wire/TREN in DMSO at 25 °C

The single‐electron transfer living radical polymerization (SET‐LRP) of vinyl chloride (VC) initiated with CHBr₃ in dimethylsulfoxide (DMSO) at 25 °C was investigated using Cu(0) powder and Cu(0) wire as the catalyst. It was determined that living kinetics and high conversion are achieved only through the proper calibration of the ratio between Cu(0) and TREN and the concentration of VC in DMSO. For both Cu(0) powder and Cu(0) wire, optimum conversion was achieved with higher levels of TREN than reported in earlier preliminary reports and under more dilute conditions. Using these conditions, 85+% conversion of VC could be achieved with Cu(0) powder and wire to produce white poly(vinyl chloride) (PVC) with M_n = 20,000 and M_w/M_n = 1.4–1.6 in 360 min. The use of Cu(0) wire provides the most effective catalytic system for the LRP of PVC allowing for simple removal and recycling of the catalyst. In the Cu(0) wire‐catalyzed SET‐LRP of VC, the consumption of Cu(0) was monitored as a function of conversion. From these studies, it is evident that the catalyst can be recycled extensively before significant exchange of Cu(0) into Cu(II)X₂ and change in catalyst surface area is observed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 164–172, 2010     

SET‐LRP of vinyl chloride initiated with CHBr3 in DMSO at 25 °C

The development of Cu(0)/TREN/CuBr₂‐catalyzed SET‐LRP of VC initiated with CHBr₃ in DMSO at 25 °C is reported. The use of CuBr₂ additive allows for the first LRP of low molecular weight VC (target DP = 100), as well as lower Cu powder loading levels, improved I_eff and control in the synthesis of higher molecular VC, targeted degree of polymerization = 350, 700, 1,000, 1,400. ¹H NMR and HSQC confirm the bifunctionality of CHBr₃ as an initiator and suggest that deleterious side‐reactions such as the formation of allylic chlorides occur primarily at the onset of the reaction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4130–4140, 2009     

Synthesis and characterization of novel poly(vinyl chloride)‐based grafts: Poly(vinyl chloride‐co‐2‐chloropropene) fitted with multiple high‐glass‐transition‐temperature polyolefin branches

The tertiary chlorine (Cl^t) content of vinyl chloride/2‐chloropropene copolymers [P(VC‐co‐2CP)] was determined by NMR spectroscopy. Copolymers containing 6.8–47.0 Cl^t's per P(VC‐co‐2CP) chain were used to initiate the cationic grafting of α‐methylstyrene, norbornadiene, indene, and norbornene with Et₂AlCl under various conditions. Grafting was demonstrated by selective solvent extraction, and the effect of the experimental conditions on the grafting efficiency was examined. Select rheological and thermal characteristics of P(VC‐co‐2CP) grafts, including the glass‐transition temperature, heat deflection temperature, and discoloration upon heating, were studied. P(VC‐co‐2CP) carrying 7–11 poly(α‐methylstyrene) or polynorbornadiene branches per chain raised the glass‐transition temperature to, or above, that of a blend control. P(VC‐co‐2CP)s fitted with polyindene or polynorbornene branches were less effective in raising the mechanical properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3644–3651, 2002     

In‐Line Monitoring of Vinyl Chloride Suspension Polymerization with Near‐Infrared Spectroscopy, 1 – Analysis of Morphological Properties

It is demonstrated that during suspension polymerizations it is possible to monitor morphological characteristics of PVC resins such as bulk density, cold plasticizer absorption and average particle diameter in‐line and in real time using NIR spectroscopy. NIR spectra are obtained at different experimental conditions, showing that the spectra are sensitive to changes in the PVC properties. Standard mathematical procedures (partial least squares regression) are used to build empirical models and correlate the morphological properties with the obtained NIR spectra, allowing for monitoring of the PVC morphology in‐line and in real time.

     

Synthesis and in vitro degradation of poly(N‐vinyl‐2‐pyrrolidone)‐based graft copolymers for biomedical applications

This work is devoted to the design of a novel family of hydrosoluble biomaterials: poly(N‐vinyl‐2‐pyrrolidone) (PVP)‐based graft copolymers. A synthesis route has been elaborated in which ω‐functionalized PVP is prepared via chain‐transfer radical polymerization, end‐group modified, and subsequently grafted onto a polyhydroxylated backbone, typically dextran or poly(vinyl alcohol). The resulting graft copolymer biomaterials are designed for use in various biomedical applications, particularly as materials with a stronger potential for plasma expansion than already existing products have. The graft copolymers are potentially degradable because the PVP grafts are connected to the polyol backbone via a hydrolytically labile carbonate or ester linkage. The degradation of the graft copolymers was performed in vitro over a period of 6 weeks. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3652–3661, 2002