Contributions to characterization of poly(vinyl chloride)–lignin blends

The present study evaluates the impact of blending organosolv and kraft lignins, which are natural polymer by‐products in the pulp and paper industry, with plasticized poly(vinyl chloride) (PVC) in flooring formulations. Also examined is the impact of replacing dioctyl phthalate, a PVC industry general‐purpose plasticizer, with diethylene glycol dibenzoate (Benzoflex 2‐45), tricresyl phosphate (Lindol), or alkyl sulfonic phenyl ester (Mesamoll) in these formulations. The influence of the different types of lignins and plasticizers on the processibility, thermal, and mechanical properties of the blends is discussed. These properties demonstrate that partial replacement of PVC (20 parts) with different lignins is feasible for some formulations that can be successfully used as matrices for a high level of calcium carbonate filler in flooring products. In addition, the data demonstrate that the presence of certain plasticizers, which interfere with the intramolecular interactions existing in lignins, may allow the lignin molecules to have more molecular mobility. The morphology and the properties of PVC plasticized lignin blends are strongly influenced by the degree and mode of the lignin plasticization and its dispersion within the PVC matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2732–2748, 2006     

Characterization of selected pigments for exterior poly(vinyl chloride) applications

Pigments selected from the iron oxide, chromium oxide and furnace black families, which offer the possibility of preferred earthtone colors, were characterized for: their stability at PVC processing temperatures; their effect on long-term ultraviolet exposure, and their infrared absorption properties that relate to heat buildup and buckling in the composite. This study has basically ranked the pigments into three categories in terms of their overall performance. Besides the earthtone color, the added economics of these pigments makes them of prime interest for external applications.     

Processing aids for poly(vinyl chloride)

Processing aids are an important class of additives for poly(vinyl chloride) (PVC). At relatively low concentration, processing aids enable the melt processing of rigid PVC and enlarge its processing windows. Discussed in this presentation are some major functions of processing aids, such as promoting PVC fusion, modifying PVC's melt rheology, and lubricating to prevent adherence of PVC melt to the processing equipment. Some examples are given to show the effects of processing aids on PVC die swell, melt fracture, melt viscosity, and PVC fusion. Commercial sources of various processing aids and typical PVC formulations for various applications are also discussed.     

Thermal stabilization of poly(vinyl chloride) by hydrotalcites,zeolites, and conventional stabilizers

Unwanted discoloration and degradation of Poly(vinyl chloride) (PVC) at processing temperatures is a matter of concern to the industrial community. Many formulations have been suggested, but to meet environmental regulations and today's market demand, a new combination of stabilizers has been designed in order to explore the probable mechanism of stabilization. A combination of hydrotalcite, zeolite, calcium stearate, and magnesium acetylacetonate is proposed. Thermal behavior in terms of released HCl and visual color examination for color stability have been investigated. Results indicate that both hydrotalcite and zeolite behave as long‐term stabilizers. In a PVC formulation having 2 phr of hydrotalcite or zeolite, the evolution times for 2 mmol of HCl were 497 and 337 min, respectively, at 180°C, but when a part of these stabilizers was replaced by some other stabilizer, a noticeable change in HCl evolution time was observed. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Studies of possible chemical emissions from PVC articles used in indoor applications and the effect on indoor air quality

Owing to their widespread use in interior applications, PVC products are frequently discussed in studies of indoor air quality. This paper reports results from the study of products in use and also products based on laboratory formulations that incorporate both unnaturally high and low levels of ingredients that could volatilize into the indoor air, thus giving a worst and best case scenario in terms of indoor emissions. Both PVC wallcovering and PVC flooring formulations have been studied, and laboratory produced samples have been subjected to gas chromatographic analysis to determine both the chemical species and the concentrations at which these can be emitted in typical interior applications. In all cases, including the worst ones, the level of these species in the indoor air is well below the permitted interior levels for the species concerned. These results, plus some outline of the concern over indoor health, are presented.     

Iron-containing compounds as flame retarding/smoke-suppressing additives for PVC

The incorporation of a range of iron-containing inorganic and organometallic compounds into a semi-rigid PVC formulation has been investigated. Limiting Oxygen Index and Smoke Density data were obtained across a wide range of formulations and the effects of the compounds on flammability and smoke generation are discussed. Iron-containing inorganic compounds appear to have little effect on the flammability of semi-rigid PVC but several of the organoiron compounds and iron oxides markedly reduce smoke formation.     

Rheological and mechanical performance of ethyl‐vinyl acetate/poly(vinyl chloride) formulations

A range of powdered ethyl‐vinyl acetate (EVA) copolymers and poly(vinyl chloride) (PVC) formulations were compounded at PVC:EVA ratios of 100:0, 60:40, 50:50, 40:60, and 0:100. Two grades of EVA with 20% and 27% of vinyl acetate (VAc) (EVA I and EVA II) and two grades of PVC with K values of 56 and 71 (PVC I and PVC II) were used in the investigation. Mechanical analysis was performed on injection molded samples of these blends, and the results showed that the tensile and flexural moduli decreased significantly with increasing EVA concentration. Rheological analysis was performed by using dual capillary rheometry, and the results showed only slight changes in shear viscosity with increasing EVA content, even at lower shear rates. Dynamic mechanical thermal analysis showed partial miscib lity of the PVC and EVA over the range of concentrations studied.     

A study of the variables affecting bubble stability in poly (vinyl chloride) plastisols

The formation of stable air bubbles during processing is one of the most critical problems encountered in many PVC plastisol applications (often referred to as the “air release problem”). Stable bubbles can lead to both cosmetic and structural defects in finished products. Analysis of the air release problem has been difficult not only because air release is affected by many variables (some of which are interrelated), but also because no air release test has been universally accepted as being reliable. This paper presents a comparison of some of the more commonly used air release tests of the PVC plastisol industry, i.e., the Huff ring test, air injection by syringe, and air entrapment by stirring. Our investigation indicates that results obtained from these air release tests strongly depend upon test procedure, test environment, plastisol age, and even the amount of plastisol in the test container. Among the test methods which were examined, air entrapment by stirring was found to be the most convenient and reliable. Possible causes for the observed discrepancies among the tests and data scatter within each test are discussed in terms of variables which affect bubble stability, such as bubble size, rheology, film stress distribution, surface tension, and the Marangoni effect.     

Stabilization of poly(vinyl chloride). IV. Color changes on heating poly(vinyl chloride)–dye systems

The stabilization of poly(vinyl chloride) (PVC) involving complementary colors has been previously reported. Obliterating polyene color with various dyes containing complementary colors with the polyene color is studied on the basis of colorimetry. The changes in the color of heated PVC containing Thren Blue IRN, Ceres Blue GN, Oplas Violet 730, Macro-Lex Violet 3R, Macro-Lex Green 5B, or Macro-Lex Red 5B were investigated using a differential colorimeter. When the PVCs containing various dyes were heated, the discoloration from the color of each dye to the color mixture of each dye and polyene color was observed with increased heating times for all systems. In particular, an achromatic color has been observed, during the heat treatments, in PVC containing blue dyes such as Thren Blue IRN or Ceres Blue GN, which set up complementary color relationship with the polyene color. Thus the color of polyenes, which appears with advancing dehydrochlorination of PVC, is masked by the blue dyes. It is also apparent that the obliteration of polyene color does not depend on the chemical influences of the dyes added, but by color mixing of polyenes and the dyes. Cool-color dyes markedly slow down the appearance of polyene colors.     

Stabilization of poly(vinyl chloride). III. Synergism between metal soaps and masking agents on the stabilization of poly(vinyl chloride)

The stabilization mechanism by synergetic metal soaps containing complementary colors was previously reported. With increased heating times, the color of heated poly(vinyl chloride) (PVC) films containing Cd/Ba and Zn/Ca synergetic soaps markedly deviated from the polyene color. These color deviations usually decreased the thermal stability of PVC. Discoloration from polyene color to blue appeared especially on PVC films containing Zn/Ca synergetic soap and was concomitant with a marked decrease in thermal stability. The stabilization of PVC containing synergetic metal soaps can be improved by masking or removing the excessive color. In this work, the addition of various masking agents, such as ethylenediaminetetraacetic acid, o-phenanthroline, triethanolamine, urea, N,N′ -dimethylolurea, melamine, stearylamide, and lactams, to PVC containing synergetic metal soaps was investigated. It was shown that these masking agents do markedly slow down the discoloration of PVC.     

Role of poly(vinylchloride) and Di-2-ethyl hexyl-phthalate in the smoke formation from plasticized poly(vinylchloride)

The increase of the smoke level from PVC plasticized with di-2-ethyl hexyl phthalate with respect to the rigid PVC is caused mainly by interaction of the plasticizer with HCl evolved from the polymer when the temperature is higher than 200°C. This interaction causes the increase of the yield of phthalic anhydride probably through HCl as catalyst for DOP decomposition but phthalic anhydride formation parallels the formation of products enabled to increase the smoke level such as phthalic acid. In the presence of metallic compounds (iron, zinc, aluminium) it is possible to favor the formation of phthalic anhydride with respect to these products which are responsible for the smoke production. Then phthalic anhydride can be used as a tracer to estimate the efficiency of an additive or a combination of additives as smoke suppressant for DOP because its smoke level varies inversely with the yield of phthalic anhydride. The best combination to reduce the smoke level from plasticized PVC is obtained with the binary systems based upon copper compound, mainly efficient as smoke suppressant for PVC and either zinc or aluminium compounds, mainly efficient as smoke suppressant for DOP.     

Effect of Wood Flour Content on the Thermal,Mechanical and Dielectric Properties of Poly(vinyl chloride)

Several composite formulations of poly(vinyl chloride)/olive wood flour (PVC/WF) were manufactured by dry‐blending PVC, wood flour, plasticizer and other processing additives in a high‐intensity mixer. The dry‐blended compounds were calendered into film samples (T = 180°C, calendered time = 8 min). The films obtained are cut into normalized samples for thermal, mechanical, and dielectric characterization. The results obtained show that stress as well as strain at break decrease sharply as the wood flour content increases. On the other hand, this filler content has little influence on the glass transition temperature. It decreases the temperature of decomposition setting and retards the PVC thermal decomposition. It increases permittivity as well as dielectric losses. The thermal stability, as measured by thermogravimetry (TGA) and differential scanning calorimetry (DSC) methods, is good enough to permit processing of these types of PVC compounds using conventional processing techniques and temperatures under 210°C.     

Molded electrode test system for evaluating wet electrical performance of flexible poly(vinyl chloride)

The molded electrode test system (METS) test has long been used with flexible poly(vinyl chloride) (PVC) electrical insulation. However, there are many questions regarding its precision and accuracy, as there is no industry‐accepted standard regarding this test. This paper aims to answer some of these questions in terms of the measurement precision as well as the ability of the test to predict wet electrical performance on wire. A repeatability study was conducted on flexible PVC compound where 10 samples were produced and tested under identical conditions. The mean insulation resistance was (550 MΩ)/(305 m) with a standard deviation of (120 MΩ)/(305 m). As the thickness of the insulation increased, the insulation resistance decreased. Furthermore, the study showed that there was no correlation between the METS test and wet volume resistivity, while there was some correlation with wet insulation resistance (IR) at high temperature, though the ability to predict wet IR from the METS test was limited. J. VINYL ADDIT. TECHNOL., 18:178–183, 2012. © 2012 Society of Plastics Engineers     

Impact reinforcement of poly(vinyl chloride)

Several theories have been advanced to explain the toughening of glassy plastics by rubbery modifiers. These have been based primarily on studies of high impact polystyrene or ABS systems, where the crazing mechanism has been shown to be most applicable. In the present study, the effects of MBS (methacrylate-butadiene-styrene) impact modifiers on PVC have been studied, utilizing both physical and microscopic techniques. Tensile test results indicate that a primary contribution of the modifier to increased toughness is a lowering of the yield stress of the PVC. Electron microscopic studies and density determinations on strained samples indicate no crazes in these MBS-modified PVC systems. These results suggest that the mechanism of impact reinforcement in PVC is based on the enhancement of localized yielding in the vicinity of the rubbery modifier particles.     

Co-rotating twin screw compounding studies of PVC formulations

A 50 mm twin screw extruder was used to study the melting profiles of various PVC formulations. Melt temperature and degree of flux are measured axially along various mixing paddle arrangements. The viscous work is correlated with the rheology of the PVC mass and effective shear rate of the intermeshing co-rotating screws. The results of this investigation are used to develop a conceptual model of compounding PVC formulations. The radial mixing patterns in paddle segments down the barrel length are analyzed by introduction of trace quantities of pigment added to the dry blend. The resulting residence time distributions coupled with localized shear rate distributions give a numerical evaluation of shear strain required to flux PVC particles into a continuous fluid mass. By proper agitator design, compounding of PVC formulations can be accomplished with minimal thermal history.     

活性炭模板制备铝酸铁及其在软PVC中的阻燃应用

以硫酸铁和硫酸铝为原料,以磷酸处理过的活性炭为模板制备铝酸铁阻燃剂。并通过X射线衍射（XRD）和红外吸收光谱（FT-IR）对合成铝酸铁阻燃剂做了表征。用极限氧指数、烟密度测试其对PVC的阻燃消烟性,当铝酸铁阻燃剂的添加量为5%（质量分数）时,阻燃后软PVC的极限氧指数达到32.8%,烟密度等级为55.45%,拉伸强度为18.36 MPa,断裂伸长率为214%,并通过热重分析对阻燃前后PVC的热降解行为做了研究。结果表明：以活性炭为模板制备的铝酸铁阻燃剂对软质PVC具有较好的阻燃消烟性能。     

Evaluation of Plastic Bonded Explosive (PBX) Formulations Based on RDX,Aluminum, and HTPB for Underwater Applications

Aluminized high explosives are known to give better underwater performance. All explosive formulations for underwater targets are filled into warheads and shells by casting method. TNT, a high explosive is used as casting medium due to its lower melting point. Plastic bonded explosives are fast replacing TNT‐based high explosive formulations for the reasons that they are more insensitive and low vulnerable explosives with better shelf life. Few aluminized plastic bonded explosive formulations based on RDX, aluminum, and HTPB have been processed, varying the aluminum content from 0 to 35% and evaluated underwater. The present paper discusses the experimental methodology adopted to evaluate the above formulations for their ballistic parameters, viz., peak over pressure and impulse. Explosion bulge tests have been conducted with each explosive formulation and extent of bulge in test plates is presented and compared with a standard underwater explosive, viz., HBX‐3.     

Plasticizers derived from cardanol: synthesis and plasticization properties for polyvinyl chloride(PVC)

Two natural plasticizers derived from cardanol (CD), cardanol acetate (CA) and epoxidized cardanol acetate (ECA), were synthesized and characterized by ¹H NMR and ¹³C NMR. The plasticizing effects of the obtained plasticizers on semi-rigid polyvinylchloride (PVC) formulations were also investigated. Two commercial phthalate ester plasticizers, dioctyl terephthalate (DOTP) and diisononyl phthalate (DINP), were used as controls. Mechanical and thermal properties, compatibility, thermal stability, microstructure, and workability were assessed by dynamic mechanical analysis (DMA), mechanical analysis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and dynamic stability analysis, respectively. Results indicated that the natural plasticizer ECA had overallsuperior flexibility, compatibility, thermal stability, and workability comparable to both controls. The obtained CA and ECA have lower volatility resistance and similar extraction and exudation resistance than that of DOTP and DINP. The CA was further blended with DOTP in soft PVC films. Results of DMA, TGA and mechanicalanalysis indicated that CA can serve as a secondary plasticizer to improve the related properties of soft PVC formulations. These CD derived plasticizers show promise as an alternative to fully or partially replace petroleum-based plasticizers.     

Dynamic mechanical analysis of poly(vinyl chloride) compounds and blends

PVC is one of the most versatile and cost effective commercial polymers. A main limitation of PVC is optimizing its fabrication characteristics and end use properties with minimum adverse effect on either. PVC compounding technology is supersensitive due to effect of subtle variations in formulations causing “inspec” products during one production run and “out-of-spec” products in another. Large variations in properties are frequently due to improper mixing. Dynamic mechanical analyses provides a method of monitoring variations in mixing and their affect on morphological structure deviations which can lead to poor processing and end use properties.     

Synthesis and application of a natural plasticizer based on cardanol for poly(vinyl chloride)

A natural plasticizer with multifunctional groups, similar in structure to phthalates, cardanol derivatives glycidyl ether (CGE) was synthesized from cardanol by a two‐step modification process and characterized by FT‐IR, ¹HNMR, and ¹³CNMR. The resulting product was incorporated to PVC (CGE/PVC), and plasticizing effect was compared with PVC incorporated with two kinds of commercial phthalate ester plasticizers bis (2‐ethylhexyl) benzene‐1,4‐dicarboxylate (DOTP) and diisononyl phthalate (DINP). Dynamic mechanical analysis and mechanical properties testing of the plasticized PVC samples were performed in order to evaluate their flexibility, compatibility, and plasticizing efficiency. SEM was employed to produce fractured surface morphology. Thermogravimetric analysis and discoloration tests were used to characterize the thermal stabilities. Dynamic stability analysis was used to test the processability of formulations. Compared with DOTP and DINP plasticized samples, CGE/PVC has a maximum decrease of 9.27% in glass transition temperature (T_g), a maximum increase of 17.6% in the elongation at break, and a maximum increase of 31.59°C and 25.31 min in 50% weight loss (T50) and dynamic stability time, respectively. The obtained CGE also has slightly lower volatility resistance and higher exudation resistance than that of DOTP and DINP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42465.