Concentration and temperature dependence of plasticizer diffusion into plasticized PVC

The diffusion of a plasticizer S₁ from a source made of PVC containing 25 wt% of S₁ into a medium made of PVC film containing another plasticizer S₂ in 15, 20, 25 and 30 wt%, was studied at temperatures ranging from 70 to 108°C. S₁ was generally diphenyl-iso-octyl phosphate (DPIP) and S₂ was dioctyl phthalate (DOP) but the reciprocal system was also studied in some cases. Starting from a reference point corresponding to a temperature of 70°C and a DOP concentration of 25 wt%, it was found experimentally that an increase Δv of the DOP volume fraction (v) or an increase ΔT of the temperature, led to the same variation of the diffusion coefficient of DPIP if ΔT/Δv ～ 139K. A reasonably close value can be obtained from a simple free-volume approach, using the literature data on the plasticizer action of DOP on PVC.     

塑化温度和成型温度对增塑PVC及PVC／PNBR弹性体力学性能的影响

当塑化温度分别为135℃和150℃时,通过测定不同成型温度下（145、150、155、160℃）压片制得的增塑PVC和PVC／PNBR共混物的断裂伸长率、拉伸强度、硬度和拉伸永久变形,研究了塑化温度和成型温度对试样力学性能的影响。结果表明：①150℃塑化温度下,物料塑化得更完全,PVC分子链间的作用力增强,试样的拉伸强度、拉伸永久变形、硬度增大;②在成型温度为145-155℃范围内,试样的断裂伸长率、拉伸强度随成型温度的提高都显著增大;③与塑化温度相比,成型温度对试样力学性能的影响更大。     

Extrusion-rotomolding of plasticized PVC formulations

In this work, we present a novel process to produce plasticized PVC articles. Plasticized PVC dispersion resin (dry blend) was extruded and poured into a hot mold. The mold was transferred to a rotomolding machine, where the final geometry was obtained. Formulations using commercial PVC suspension resin and three different types of plasticizers were prepared under different processing conditions. The physical appearance of the articles and the tensile properties of the materials were evaluated.     

Antioxidant effects in PVC plasticized with DIDA

Antioxidants such as bisphenol A (BPA) have long been recommended for retention of physical properties on oven-aging of PVC plasticized with certain plasticizers. We have shown how BPA inhibits oxidative fragmentation of plasticizers such as diisodecyl adipate (DIDA) and thus decreases apparent volatility, and how it improves retention of modulus, elongation, and low temperature flexibility. Low concentrations are more beneficial than either zero or high concentrations, especially on longer aging. At higher concentrations, although the plasticizer is retained in the PVC, it becomes less efficient at low temperature, and low-temperature flex is impaired while elongation is preserved. DIDA exudes during oven-aging unless oxidation occurs to prevent it. When BPA is present, exudation is worst at the most efficient concentrations of antioxidant. This appears to be the normal incompatibility of DIDA at 105°C which is permitted by the antioxidant. On oxidation, the dielectric constant of DIDA rises into the 4–8 range, signifying compatibility with PVC, and the DIDA does not exude.     

Crosslinking of plasticized PVC used in coated fabrics

Crosslinking is effective in improving the properties of plasticized poly(vinyl chloride) (PPVC), such as mechanical, chemical, and thermal resistance. In this study, the crosslinking was carried out using di‐tert‐butyl peroxide as an initiator in the presence of 1,1,1‐trimethylolpropane trimethacrylate (TMPTMA) as a crosslinking agent at two different curing temperatures. The degree of crosslinking was measured in terms of gel content and tensile strength. Upon increasing the amount of peroxide to an optimum level, the gel content and tensile strength increased to a maximum point, and above this level, the peroxide caused a slight decrease in crosslinking, which was due to the scission of PPVC chains during thermal degradation. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Correlation of the glass transition temperature of plasticized PVC using a lattice fluid model

A model has been developed to estimate the glass transition temperature of polymer+plasticizer mixtures (up to 30 wt% plasticizer). The model is based on the Sanchez-Lacombe equation of state and the Gibbs-DiMarzio criterion, which states that the entropy of a mixture is zero at the glass transition. The polymers studied included polystyrene and poly(vinyl chloride). The plasticizers studied included a wide range of chemicals from methyl acetate to di-undecyl phthalate. The model qualitatively accounted for the effect of different plasticizers on the mixture glass transition temperature.     

The dc volume resistivity of plasticized PVC

A study has been made of the dc volume resistivity of plasticized PVC using a guarded-electrode system in a sensitive vibrating capacitor–electrometer circuit. Transient effects were found to be pronounced in all but the least plasticized compositions, and the behavior in general was non-Ohmic. The resistivity decreases with plasticizer concentration and with temperature; an Arrhenius-type relationship is observed and resistivity undergoes an inflection at the glass transition temperature. The mechanism of conduction appears to be electrolytic rather than charge injection or semiconduction.     

Rates of property change in plasticized filled PVC compounds

Rheological and mechanical properties of polyvinyl chloride (PVC) compounds vary with the polymer entanglement state at the time of testing. Controlled shearing episodes and thermal histories applied to the compounds produce major property variations. These then relax toward steady-state values at rates which are consistent with diffusion-controlled processes, presumably connected with the development of steady-states in entanglement couplings. Activation energies of 4–7 kcal/mol apply to the proposed re-entanglement processes. Rates of property variation can be altered by the addition of fillers to the compounds, the interactions between polymer and filler being an important factor in this regard. CaCO₃ samples with strong affinity for the PVC retard the rate of property variations (i.e., the filler tends to stabilize non-steady-state entanglement couplings). Fillers, surface treated so as not to interact strongly with the polymer, produce lesser effects on relaxation rates. The data indicate the feasibility of controlling both the sensitivity of polymer properties to processing variables, and the rates of property change associated with the attainment of steady-state polymer entanglement morphologies.     

Leaching of plasticized PVC: Effect of irradiation

Highly irradiated (2–26 MGy) polyvinyl chloride (PVC) was leached in an alkaline solution to investigate the impact of high doses on the leaching process and on the nature of the leaching products. The results show that leaching is controlled by diffusion phenomena as described by Fick's second law. The apparent diffusion coefficient (D_a) of plasticized PVC leaching products can be calculated for each sample. Irradiation at high dose causes D_a to diminish; this can be attributed to crosslinking and grafting reactions occurring during irradiation. The material microstructure thus becomes less permeable during radiolysis, which slows down the migration of species. Organic products of leaching are plasticizers contained in plasticized PVC or their degradation products. The main organic leaching products are phthalic ions formed by the hydrolysis of phthalic esters in alkaline leaching solution. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

PVC塑化木粉及其吸水性

将木粉和PVC共混，同时加入相容剂POE—MAH，三者经挤出机挤出形成化学反应相容。生成PVC塑化木粉。研究了该塑化木粉的吸水性。研究表明：体系中PVC比例增加、木粉比例减小时。临界含水量变小，即吸水性变小。     

The biodeterioration of plasticized PVC and its prevention

Plasticized polyvinyl chloride will be attacked by microorganisms. The microorganisms will use the plasticizer as a carbon source, whereas favorable growth conditions, like water and oxygen, promotes their growth. A clear effect of the temperature of the water used in leaching experiments on the rate of fungal growth on the foil surface could be demonstrated. Studies also showed a difference in susceptibility of several types of plasticizers to fungal attack. The plasticizers can be divided into several classes based on their susceptibility to fungal attack. Detailed studies on the microbiological population on foil surfaces showed the predominating position of fungi. This indicated a metabiotic system between fungi and bacteria on foil surface. Addition of biocides, during manufacturing of PVC, primarily must have fungistatic properties. The fungistatic activity of 10,10′-oxybisphenoxyarsine (OBPA) is very high, and in consequence, very low concentration must be available on foil surfaces which will prevent fungal growth. These low amounts on foil surfaces are directly correlated to the amount of OBPA insite of the foil. The transport process of the insite OBPA to the surface of the foil will principally be determined by the recepe of the foil. Therefore the application concentration recommended to ensure to achieve the minimum inhibitory concentration for fungi on the foil surface will be determined from where the application actually manifests itself.     

Stress-cracking resistance of polycarbonate in contact with plasticized PVC compounds

Polymeric polyester plasticizers cause less cracking in polycarbonate than monomeric esters. Certain high-viscosity polymeric plasticizers over 100,000 centipoise, and several in the 10,000 to 25,000 range, did not stress-crack polycarbonate. But viscosity is not the only determinant. Chemical type, level of use, polarity, and severity of the environment all contribute to crack development in stressed polycarbonate.     

环境友好型增塑剂增塑聚氯乙烯体系的性能表征

以传统增塑剂邻苯二甲酸二辛酯(DOP)为比较对象,研究了对苯二酸二辛酯(DOTP)、乙酰柠檬酸三丁酯(ATBC)、己二酸二辛酯(DOA)、癸二酸二辛酯(DOS)4种环境友好型增塑剂对聚氯乙烯(PVC)体系的力学性能和耐油、耐溶剂性能的影响,并采用傅里叶变换红外光谱法和差示扫描量热法对试样分子结构进行了表征。结果表明:①ATBC/PVC体系的Tg最高(-22.1℃);DOS/PVC体系的Tg最低(-65.4℃),耐寒性最佳;②ATBC、DOA、DOS增塑PVC的力学性能整体上优于DOP增塑的PVC;③在异辛烷、正己烷和ASTM 1#标准油3种萃取剂中,5种增塑剂在正己烷中的最终抽出率最大;在同一萃取剂中,ATBC的最终抽出率最小;④针对不同使用领域,DOPT、ATBC、DOA、DOS可替代DOP增塑PVC。     

Viscoelastic properties of plasticized PVC reinforced with cellulose whiskers

New nanocomposites are processed with a plasticized poly(vinyl chloride) matrix reinforced by cellulose whiskers whose characteristics are a high aspect ratio and a large interface area. Dynamic mechanical analysis performed on samples reinforced with a filler fraction of up to 12.4 vol % gives the viscoelastic properties of the composite above and below its glass transition temperature. Different theoretical predictions are proposed to describe this behavior, but none of them is found wholly satisfactory for describing the reinforcing effect of these fillers. A model based on the Halpin–Kardos equation, with the assumption of an immobilized phase around the whiskers, is developed to account for significant decrease in the modulus drop, on passing above the glass transition temperature. The small discrepancy between this model and the experimental modulus measured in the rubber plateau is discussed as a possible effect of a percolating whisker network whose crosslinks are assured by chains adsorbed onto the whisker surface. Swelling experiments support this hypothesis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1797–1808, 1999     

Annealing of plasticized PVC. Dilatometric and DSC observations

Isothermal dilatometric measurements on quenched, plasticized PVC have been made at a series of temperatures, and a mathematical expression has been obtained to described the specific volume as a function of time. The results of these measurements, along with those obtained using differential scanning colorimetry (DSC) for the change in enthalpy accompanying annealing, clearly show a change in the character of the annealing process with rising temperature; but the underlying molecular kinetic mechanism apparently remains unchanged.     

PVC树脂生产中产生塑化片的原因与改进措施

分析了PVC树脂生产中产生塑化片的原因,针对储槽搅拌器、离心机、星形下料器和输送管线提出了改进措施,并在料仓底部下料管线处增加了振动筛,改造后效果良好.     

Interaction of plasticizers with PVC: Phase behavior and thermomechanical properties of plasticized PVC

The hypothesis that plasticizer phase separation broadens glass transition temperatures when the temperature of a PVC/plasticizer formulation is raised was tested using dynamic mechanical analysis and NMR. NMR is a reasonable tool for detecting the phases. Phase separation in the vicinity of T_g is an explanation for the broadening of the transition region. But a variety of behavior is possible depending on the details of the measurement of T_g and on the thermal history of the sample. Phase separation broadening is in addition to the broadening caused by changes in the dimensionality of the damped Debye lattice described by Tobolsky.     

Biodeterioration of plasticized PVC/montmorillonite nanocomposites in aerobic soil environment

The aim of this study was to assess the effect of montmorillonite nanofillers, Cloisite Na⁺ and Cloisite 30B, on the biodeterioration of PVC-based nanocomposites plasticized by means of dioctyl adipate (DOA), dioctyl phthalate (DOP) and modified poly(propylene adipate) (PPA), in the aerobic environment of soil (soil burial test, time of exposure: 198 days). Tests were carried out at 25 ± 1 °C, under moisture-controlled (55 %) and aerobic conditions. The extent of the biodeterioration process was evaluated on the basis of changes in weight, tensile strength and elongation-at-break values. Finally, analysing chemical structures using FTIR and visual observation, both macroscopic and microscopic via scanning electron microscopy assisted in the evaluation process. The results of this study suggested that plasticized PVC/montmorillonite nanocomposites have an increased susceptibility for undergoing biological deterioration in comparison with plasticized PVC. In each instance, adding Cloisite 30B resulted in reducing the resistance of PVC/montmorillonite nanocomposites to the actions of microorganisms. In the case of Cloisite Na⁺ as the filler, results cannot be clearly quantified, although a negative influence prevailed, particularly a change in colour, whose change intensity was also dependent on the type of plasticizer, increasing in the following sequence: PVC/DOA/Cloisite Na⁺ > PVC/DOP/Cloisite Na⁺ > PVC/PPA/Cloisite Na⁺. However, each sample containing Cloisite Na⁺ achieved a lower rate of degradation (by normalised weight loss and FTIR) compared with nanocomposites containing Cloisite 30B. This can be attributed to the migration and accumulation of Cloisite Na⁺ on the surface of the nanocomposites particles where the former phenomenon producing a surface barrier which caused a reduction in the permeability of the material toward water and microorganisms, during the test.     

Cooperation between chemical and physical networks in crosslinked and plasticized PVC

The effect of crosslinking of plasticized PVC on the mechanical properties has been investigated. Crosslinking was performed by using a dithioltriazine, and penetration as a function of temperature was used to follow the changes in mechanical properties. Changes in the melting behavior were detected by differential scanning calorimetry. Even rather low levels of gel content gave a substantial reduction in penetration in the interval 60–110°C, while a more complete reaction prevented major penetration up to at least 200°C. The penetration curve of heavily crosslinked materials showed several plateaus and the transitions could be related to melting of different crystallites formed by annealing at different temperatures. The physical network formed by the crystallites constitutes an important complement to the chemical network in plasticized PVC crosslinked by dithioltriazine. Both the amount and the melting temperature of the crystallites increased after annealing. The introduction of the chemical network further improved the heat resistance of the crystallites. The presence of the two networks will therefore show a synergistic effect with respect to the mechanical properties at increased temperatures.