Rheological behavior and thermal properties of poly(butyl acrylate‐co‐2‐ethylhexyl acrylate)‐grafted vinyl chloride resin

The rheological behavior and thermal properties of a poly(butyl acrylate‐co‐2‐ethylhexyl acrylate) [P(BA‐EHA)]‐grafted vinyl chloride (VC) composite resin [P(BA‐EHA)/poly(vinyl chloride) (PVC)] and its materials were investigated. The rheological behavior, thermal stability, and Vicat softening temperature (VST) of P(BA‐EHA)/PVC were measured with capillary rheometry, thermal analysis, and VST testing, respectively. The effects of the P(BA‐EHA) content and the polymerization temperature of grafted VC on the rheological behavior of the composite resin were examined. The weight loss of the composite resin and its extracted remainder via heating were analyzed. The influence of the content and crosslinking degree of P(BA‐EHA) and the polymerization temperature of the grafted VC on VST of the materials was determined. The results indicated the pseudoplastic‐flow nature of the composite resin. The flow property of the modified PVC resin was improved because of the incorporation of the acrylate polymer. The molecular weight of PVC greatly influenced the flow behavior and VST of the composite resin and its materials. The flowability of the composite resin markedly increased, and the VST of its materials decreased as the polymerization temperature of the grafted VC increased. The initial degradation temperature of the composite resin increased as the P(BA‐EHA) content increased. The VST of the samples was enhanced a little as the content of the crosslinking agent increased in P(BA‐EHA). As expected, the composite resin, with good impact resistance, had better heating stability and flowability than pure PVC, whereas the VST of the material decreased little with increasing P(BA‐EHA) content. Therefore, P(BA‐EHA)/PVC resins prepared by seeded emulsion polymerization have excellent potential for widespread applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 419–426, 2005     

Synthesis and some properties of anthracene and anthraquinone incorporated poly(vinyl chloride) and the ion exchange resin therefrom

Poly(vinyl chloride) has been modified by chlorine displacement reaction with 2-anthrol and anthraquinone-2-ol. The condensates (PVC-ACOL and PVC-AQOL) are insoluble in all solvents common to PVC and have been characterized by elemental and IR spectra analysis. The initial decomposition temperature of these condensates follow the trend: PVC-AQOL (250°C) > PVC-ACOL (200°C) > PVC(190°C) and the overall thermal stabilities beyond 60% decomposition follows the same trend. Permittivity and dielectric loss of these condensates sharply fall with increasing applied frequency (10–1.3 ×10⁷ Hz) to a limiting constant value. In contrast, for unmodified PVC these values are low and remain independent of frequency in the same range. Sulfonation of these PVC condensates affords a weak acid resin with ? COOH and ? OH ionogenic groups, but no strong sulfonic acid groups due presumably to oxidative degradation of the PVC matrix.     

Thermal characterization of poly(vinyl chloride) samples prepared by living radical polymerization: Comparison with poly(vinyl chloride) prepared by free radical polymerization

Poly(vinyl chloride) (PVC) samples were synthesized by a living radical polymerization (LRP) method and compared with commercial PVC prepared by the conventional free radical polymerization (FRP). The differences were assessed, for the first time, in terms of viscosimetry parameters and thermal analysis. The LRP method used to prepare the PVC‐LRP samples is the only one available to obtain this polymer free of structural defects, being of commercial interest in a view of preparing a new generation of PVC‐based polymer with outstanding performance. The polymerization temperature selected (35°C) to prepare the LRP samples is currently used in the industry to prepare PVC‐FRP grades with moderate to high molecular weight. Since the thermal stability is a direct consequence of the polymer structure, this study is of vital importance to understand the potential of new PVC‐LRP. The thermoanalytical measurements demonstrate an enhanced thermal stability of PVC‐LRP when compared with its FRP counterpart. The PVC‐LRP sample with very low molecular weight reveals a higher thermal stability than the most stable PVC‐FRP sample. It is the first report dealing with thermal analysis of PVC prepared by LRP. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of epoxy resin on thermal,dynamic, and mechanical properties of rigid poly(vinyl chloride)

This work is concerned with the effect of an epoxy resin on the properties of rigid poly(vinyl chloride) (PVC). The epoxy resin concentrations of 0, 1, 2, 4, and 6 phr were used to prepare PVC/epoxy polymer blends and the viscoelastic behavior of the blends was investigated by dynamic mechanical thermal analysis and rheometry test. The results revealed that the low molecular weight epoxy resin did not greatly affect the viscoelastic properties of PVC. From the morphological point of view, the smallest droplet size of epoxy dispersed in the polymer blends was found in the sample with 1 phr epoxy resin, and the largest one was for the sample with 6 phr epoxy. The thermal properties of PVC/epoxy blends were investigated using differential scanning calorimetry and thermogravimetric analysis, as well. According to our research, the initial decomposition temperature of PVC was increased about 6°C by the incorporation of epoxy resin. The results of tensile test showed that the addition of epoxy resin decreased the elongation‐at‐break of PVC about 50% in the samples without calcium carbonate and about 25% in the samples containing calcium carbonate. Moreover, the failure mode of PVC was changed from a ductile fracture mode to a brittle fracture mode with the addition of epoxy resin. J. VINYL ADDIT. TECHNOL., 25:E72–E79, 2019. © 2018 Society of Plastics Engineers     

The effect of crystallites on the rheological properties of microphase‐separated PVC‐PBA‐PVC triblock copolymers obtained by single electron transfer‐degenerative chain transfer living radical polymerization

Linear and nonlinear rheological properties of poly(vinyl chloride) (PVC)‐poly(n‐butyl acrylate)‐PVC triblocks of different compositions, obtained by single electron transfer‐degenerative chain transfer living radical polymerization, are investigated, focusing on the effect of crystallites. Dynamic mechanical thermal analysis results show the existence of two glass transition temperatures, denoting microphase segregation. However, rather than phase separation, it is the presence of two types of crystals that melt at T_m1 = 127 ± 0.8°C and T_m2 = 185 ± 2°C, respectively, the factor that determines the rheological response of the copolymers. To the difference with PVC homopolymers, extrusion flow measurements at very low temperatures (T = 100°C) are possible with the copolymers. A change in the viscosity‐temperature dependence is observed below and above the lowest melting temperature. Notwithstanding the microphase separation and the presence of crystallites, experiments carried out in conditions similar to industrial processing reveal a remarkable viscosity reduction for our copolymers with respect to PVC obtained by single electron transfer‐degenerative chain transfer living radical polymerization, conventional PVC, and PVC/[diethyl‐(2‐ethylhexyl) phthalate] compounds. Extrudates free of surface instabilities are obtained at low extrusion temperatures, such as 90–100°C. J. VINYL ADDIT. TECHNOL., 21:24–32, 2015. © 2014 Society of Plastics Engineers     

Influence of crystallinity in the curing mechanism of PVC plastisols

The influence of the crystalline areas observed in poly(vinyl chloride) (PVC) the mechanical and thermal properties of PVC plastisols was studied. Several industrial‐degree PVC resins were used to obtain a broad range of molecular weights and processing conditions for PVC plastisols. The gelation process was fully studied at different temperatures and was related to the existence of crystalline areas at high temperatures, even near the glass transition. A simple explanation of the phenomena observed during the gelation of plasticized PVC is proposed, according to the variation in the mechanical and thermal properties at different temperatures. The final gelation was obtained at 140–150°C, which was a lower temperature than those at the beginning of the thermal degradation process. The thermodynamic aspects of the gelation of plasticized PVC were mainly controlled by the PVC resin properties, whereas the plasticizer only influenced the diffusion and stability of the material. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 538–544, 2004     

Solid‐state characterization and the thermal properties of stereoregular poly(vinyl chloride) prepared by urea clathrate polymerization

The solid‐state characterization of highly stereoregular poly(vinyl chloride) (PVC) prepared by urea clathrate polymerization was carried out by using various instrumental analyses. The structural differences of PVC appeared most remarkably in solubility to organic solvents, IR, WAXD, and solid‐state ¹³C‐NMR spectra. The value of the glass transition temperature (T_g) was about 90°C, not as high as expected, although its detection was quite difficult. The thermal stability was poor, as evidenced by the easy discoloration of this polymer by heat treatment, which was related to the absence of a termination reaction. Dynamic ESR spectra in the solid state clearly indicate that the radical formation occurs at such a low temperature as 160°C in the initial degradation stage. The degradation characteristics of urea clathrate PVC were critically discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2820–2825, 1999     

Investigation of the effects of nonisothermal suspension polymerization of vinyl chloride on the fusion and degradation behavior of poly(vinyl chloride)

Thermal stability of poly(vinyl chloride) (PVC) samples polymerized under a temperature trajectory was studied from the point of view of morphological and microstructural characteristics. The results are compared with those of the PVC samples obtained by polymerization at constant temperature having the same K value. The Brabender^® plastograph data indicated that the final PVC synthesized with the temperature trajectory showed lower fusion time and higher thermal stability time. The nonisothermal condition also increased the degree of fusion of the final PVC resin, reflecting lower temperature/time required to process it. It was found that the thermal stability of nonisothermally produced PVC as characterized by dehydrochlorination rate decreased (improved) with the increasing monomer conversion until a minimum value was reached that corresponded to the conversion at the pressure drop. However, the dehydrochlorination rate remains almost constant with conversion for an isothermal grade PVC resin. Although the evolution of the number of internal double bonds as well as extent of discoloration of PVC with conversion shows a decreasing trend, the labile chlorine concentration exhibits a maximum at early conversion. The reason for the former can be explained by the temperature dependence of reactions forming defect structures, which are kinetically controlled and thus favored at higher temperatures. The latter, however, can be explained because of the increasing importance of transfer reactions to polymer with increasing polymer concentration. Finally, the results from differential thermogravimetry verify an improvement in thermal stability of the final PVC prepared by using a temperature trajectory during vinyl chloride monomer suspension polymerization. J. VINYL ADDIT. TECHNOL., 23:259–266, 2017. © 2015 Society of Plastics Engineers     

A tough noncombustible material prepared by grafting of poly(2‐ethylhexyl acrylate) with vinyl chloride

A noncombustible tough poly(vinyl chloride) (tPVC) was prepared by suspension‐grafted copolymerization of poly(2‐ethylhexyl acrylate) (poly‐EHA; elastomer) with vinyl chloride (VC). Elastomer (poly‐EHA) was prepared by emulsion, mainly homopolymerization of 2‐ethylhexyl acrylate at a temperature of 30 ± 0.1°C in the presence of a redox system and with the advantage of dosing the monomer into two portions. Grafted‐suspension copolymerization of poly‐EHA with VC was carried out at 54 ± 0.1°C, keeping other reaction conditions only slightly modified in comparison with those for the polymerization of pure VC. An optimum content of the incorporated poly‐EHA in PVC was found to be in the range 7.5–8.5 wt %, whereas notched toughness of 85–87 kJ m^?2 was reached. Both below and above the found range of the content of poly‐EHA, the toughness decreases. A copolymer prepared by a direct‐emulsion copolymerization of 2‐EHA and VC (poly‐EHA‐co‐VC) exhibited worse mechanical properties than the copolymer prepared by two polymerization steps. On the basis of experimental results, effects of the reaction procedure on the properties of resulting material are described. In addition to good mechanical properties, tPVC also shows its noncombustibly. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2355–2362, 2002     

Study on the damping of EVM based blends

The mechanical and damping properties of blends of ethylene‐vinyl acetate rubber(VA content >40 wt %) (EVM)/nitrile butadiene rubber (NBR) and EVM/ethylene‐propylene‐diene copolymer (EPDM), both with 1.4 phr BIPB (bis (tert‐butyl peroxy isopropyl) benzene) as curing agent, were investigated by DMA. The effect of polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and dicumyl peroxide (DCP) on the damping and mechanical properties of both rubber blends were studied. The results showed that in EVM/EPDM/PVC blends, EPDM was immiscible with EVM and could not expand the damping range of EVM at low temperature. PVC was miscible with EVM and dramatically improved the damping property of EVM at high temperature while keeping good mechanical performance. In EVM/NBR/PVC blends, PVC was partially miscible with EVM/NBR blends and remarkably widened the effective damping temperature range from 41.1°C for EVM/NBR to 62.4°C, while CPVC mixed EVM/NBR blends had an expanded effective damping temperature range of 63.5°C with only one damping peak. Curing agents BIPB and DCP had a similar influence on EVM/EPDM blends. DCP, however, dramatically raised the height of tan δ peak of EVM/NBR = 80/20 and expanded its effective damping temperature range to 64.9°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of a novel polyester plasticizer based on glyceryl monooleate and its application in poly(vinyl chloride)

The use of bio‐based polymeric plasticizers could expand the application range of plasticized poly(vinyl chloride) (PVC) materials. In this study, a novel bio‐based polyester plasticizer, poly(glutaric acid‐glyceryl monooleate) (PGAGMO), was synthesized from glutaric acid and glyceryl monooleate via a direct esterification and polycondensation route. The polyester plasticizer was characterized by gel permeation chromatography, ¹H‐nuclear magnetic resonance, and Fourier‐transform infrared spectroscopy. The plasticizing effect of PGAGMO on PVC was investigated. The melting behavior, thermal properties, and mechanical properties of PVC blends were studied. The results showed that the PGAGMO could improve the thermal stability and reduce the glass transition temperature of PVC blends; when phthalates were substituted by PGAGMO in PVC blends, the thermal degradation temperature of PVC blends increased from 251.1°C to 262.7°C, the glass transaction temperature decreased from 49.1°C to 40.2°C, the plasticized PVC blends demonstrated good compatibility, and the decrement of the torque and the melt viscosity of PVC blends were conducive to processing. All results demonstrated that the PGAGMO could partially substitute for phthalates as a potential plasticizer of PVC. J. VINYL ADDIT. TECHNOL., 22:514–519, 2016. © 2015 Society of Plastics Engineers     

The Mathematical Models of the Initial Stage of the Thermal Degradation of Poly(Vinyl Chloride)

Abstract

The mathematical models of the initial stage of the thermal dehydrochlorination of PVC are proposed. It is shown that abnormal unstable fragments having constants of rates of degradation equal to 10^?3–10^?4sec^?1 have the greatest influence on the thermal degradation of PVC at 180–200°C. The groups having chlorine near tertiary carbon and chloroallylic groups may be such fragments.     

Development and characterization of reactively extruded PVC/polystyrene blends

PVC/PS blends are obtained through a reactive extrusion–polymerization method by the absorption of a solution of styrene monomer, initiator, and a crosslinking agent in commercial suspension‐type porous polyvinyl chloride (PVC) particles, forming a dry‐blend with a relatively high monomer content. These PVC/styrene dry‐blends are reactively polymerized in a twin‐screw extruder in the melt state. They do not contain monomer residues as detected by GC. The transparency, fracture surface morphology, thermal stability, rheology and static and dynamic mechanical properties of these blends are compared to physical PVC/PS blends at similar compositions. Owing to the high polymerization temperature (180°C), short PS chains are formed in the reactive extrusion process. These short chains are dispersed both as a separate phase of ～2 μm particles (recognized by SEM) and also as molecularly dispersed chains enhancing plasticization and compatibilization. The molecularly dispersed short PS chains tend to plasticize the PVC phase, reducing its melt viscosity and glass transition temperature. The content of the short PS chains forming the dispersed separate PS particles is too low for DMTA to detect a separate T_g. Thus, reactively extruded PVC/PS blends exhibit single T_g transitions at lower temperatures compared with the neat PVC. Migration of the PVC's low‐molecular‐weight additives (lubricants and thermal stabilizer) to the PS phase is observed in the physical PVC/PS blends, causing antiplasticization of the PS phase. This results in both reduction of the T_g and an increase in the thermal stability of the PS phase in the physical PVC/PS blends. Comparing TGA thermograms of reactively extruded and physical PVC/PS indicates that the PS formed in the extruder is different from the commercial PS. This can stem from various chemical reactions that can take place in the studied reactive polymerization process. Polym. Eng. Sci. 44:1473–1483, 2004. © 2004 Society of Plastics Engineers.     

Catalytic effect of 2,2′‐diallyl bisphenol A on thermal curing of cyanate esters

Cyanate esters are a class of thermal resistant polymers widely used as thermal resistant and electrical insulating materials for electric devices and structural composite applications. In this article, the effect of 2,2′‐diallyl bisphenol A (DBA) on catalyzing the thermal curing of cyanate ester resins was studied. The curing behavior, thermal resistance, and thermal mechanical properties of these DBA catalyzed cyanate ester resins were characterized. The results show that DBA is especially suitable for catalyzing the polymerization of the novolac cyanate ester resin (HF‐5), as it acts as both the curing catalyst through depressing the exothermic peak temperature (T_exo) by nearly 100°C and the toughening agent of the novolac cyanate ester resin by slightly reducing the elastic modulus at the glassy state. The thermogravimetric analysis and dynamic mechanical thermal analysis show that the 5 wt % DBA‐catalyzed novolac cyanate ester resin exhibits good thermal resistance with T_d⁵ of 410°C and the char yield at 900°C of 58% and can retain its mechanical strength up to 250°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1775–1786, 2006     

Characterization of PVC cable insulation materials and products obtained after removal of additives

Organic solvents cyclohexane, dichloromethane, hexane, and tetrahydrofuran were tested to separate the dioctylphthalate (DOP) as plasticizer from the poly(vinyl chloride) (PVC)‐based materials. It was found that the efficiency of ultrasound‐enhanced hexane extraction of the DOP from PVC is 70% and the efficiency of the separation of the DOP and other compounds from the PVC by dissolution in THF followed by subsequent precipitation was 98–99%. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to characterize the thermal behavior of PVC materials before and after extraction of plasticizers. It was found that during heating in the range 20–800°C the total mass loss measured for the nontreated, extracted, and precipitated PVC samples was 71.6, 66.6, and 97%, respectively. In the temperature range 200–340°C, the release of DOP, HCl, and CO₂ was observed by simultaneous thermogravimetry (TG)/FTIR. The effect of plasticizers on thermal behavior of PVC‐based insulation material was characterized by DSC in the range ?40–140°C. It was found that, concerning the PVC cable insulation material before treatment, the value of the glass transition temperature (T_g) was 1.4°C, whereas for the PVC sample extracted by hexane, the value of T_g was 39.5°C and for the PVC dissolved in THF and subsequently precipitated, the value of T_g was 80.4°C. Moreover, the PVC samples after extraction of plasticizers, fillers, and other agents were tested to characterize their thermal degradation. The TG and FTIR results of chemically nontreated, extracted, and precipitated samples were compared. The release of DOP, HCl, CO₂, and benzene was studied during thermal degradation of the samples by FTIR. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 788–795, 2006     

Thermal characteristics and pyrolysis of methyl‐di(phenylethynyl)silane resin

Thermal stability of a recently synthesized polymeric methyl‐di(phenylethynyl)silane (MDPES) resin was studied using a number of thermal and spectrometric analytical techniques. The polymer exhibits extremely high thermal stability. Thermogravimetric analysis (TGA) shows that the temperature of 5% weight loss (T_d5) was 615°C and total weight loss at 800°C was 8.9%, in nitrogen atmosphere, while in air, T_d5 was found to be 562°C, and total weight loss at 800°C was found to be 55.8% of the initial weight. Differential thermal degradation (DTG) studies show that the thermal degradation of MDPES resin was single‐stage in air and two‐stage in nitrogen. The thermal degradation kinetics was studied using dynamic TGA, and the apparent activation energies were estimated to be 120.5 and 114.8 kJ/mol in air, respectively, by Kissinger and Coats–Redfern method. The white flaky pyrolysis residue was identified to be silicon dioxide by FTIR and EDS, indicating that the thermal stability of polymer may be enhanced by the formation of a thin silicon dioxide film on the material surface. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 103: 605–610, 2007     

Synthesis and characterization of melt‐processable polyimides derived from 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene

A series of molecular‐weight‐controlled imide resins end‐capped with phenylethynyl groups were prepared through the polycondensation of a mixture of 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene and 1,3‐bis(4‐aminophenoxy)benzene with 4,4′‐oxydiphthalic anhydride in the presence of 4‐phenylethynylphthalic anhydride as an end‐capping agent. The effects of the resin chemical structures and molecular weights on their melt processability and thermal properties were systematically investigated. The experimental results demonstrated that the molecular‐weight‐controlled imide resins exhibited not only meltability and melt stability but also low melt viscosity and high fluidability at temperatures lower than 280°C. The molecular‐weight‐controlled imide resins could be thermally cured at 371°C to yield thermoset polyimides by polymer chain extension and crosslinking. The neat thermoset polyimides showed excellent thermal stability, with an initial thermal decomposition temperature of more than 500°C and high glass‐transition temperatures greater than 290°C, and good mechanical properties, with flexural strengths in the range of 140.1–163.6 MPa, flexural moduli of 3.0–3.6 GPa, tensile strengths of 60.7–93.8 MPa, and elongations at break as high as 14.7%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Preparation of high‐molecular‐weight poly(N‐vinylcarbazole) by the photoinduced low‐temperature solution polymerization of N‐vinylcarbazole in 1,1,2,2‐tetrachloroethane

For the preparation of high‐molecular‐weight (HMW) poly(N‐vinylcarbazole) (PVCZ) with a narrow molecular weight distribution, N‐vinylcarbazole (VCZ) was solution‐polymerized in 1,1,2,2‐tetrachloroethane (TCE) at ?20, 0, and 20°C with photoinitiation. The effects of the polymerization temperature and the concentrations of the polymerization solvent and photoinitiator on the polymerization behavior and molecular parameters of PVCZ were investigated. A low polymerization temperature with photoirradiation was successful in obtaining HMW PVCZ with a smaller temperature rise during polymerization than that for thermal free‐radical polymerization by azobisisobutyronitrile (AIBN). The photo‐solution‐polymerization rate of VCZ in TCE was proportional to [AIBN]^0.45. The molecular weight was higher and the molecular weight distribution was narrower for PVCZ made at lower temperatures. For PVCZ prepared in TCE at ?20°C with a photoinitiator concentration of 0.00003 mol/mol of VCZ, a weight‐average molecular weight of 920,000 was obtained, with a polydispersity index of 1.46, and the degree of transparency converged to about 99%. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2391–2396, 2003     

Poly(vinyl chloride)–polyol (AB)x block copolymers: Synthesis,characterization, and mechanical properties

Poly(vinyl chloride)–polyol (AB)_x block copolymers have been prepared by the condensation polymerization of low-molecular-weight hydroxy-terminated poly(vinyl chlorides) (PVC) and diisocyanate-capped polyester and polyether diols. The difunctional poly(vinyl chlorides) were synthesized by ozonization of commercial resin followed by metal hydride reduction. The (AB)_x block copolymers, which contained 3000 or 4300 molecular weight PVC block sizes and 1000–2000 molecular weight polyol segments, had a wide range of mechanical properties, depending on overall polymer structure. Tensile strengths ranged from 7.8 to 31.5 MPa, elongations from 125% to 610% and torsional stiffness temperatures (T_f) from 25°C to ?22°C.