Improving the Long-Term Performance of Poly(Vinyl Chloride) (original) (raw)
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Viscoelastic and thermal characterization of crosslinked PVC
European Polymer Journal, 2006
Soft PVC is employed for the manufacturing of a wide range of products with different properties and a relatively low cost. The utilization of soft PVC is restricted by the poor thermal, chemical and mechanical resistance properties. Also, plasticizer migration can modify the properties or can make useless the materials for some applications because of toxicity or a general loss of properties. PVC crosslinking is the most effective way to improve mechanical and transport properties of rigid or flexible PVC at high temperatures, but at the same time the thermal stability of PVC may be significantly reduced. In this work, the crosslinking reaction of plasticized poly(vinyl chloride) (PVC) through difunctional amines was studied. The mechanisms involved in the crosslinking reaction were explained by Fourier transform infrared (FTIR) analysis. The thermal activated crosslinking reaction was studied by cone and plate rheometry, analyzing the evolution of viscoelastic properties of the suspension as a function of time and temperature. The effect of the addition of crosslinking agents on the thermal stability of the polymer was studied by thermogravimetric analysis (TGA), which revealed that crosslinking reactions promote thermal degradation phenomena in the polymer matrix. This is attributed to the formation of HCl and other species promoting polymer degradation during crosslinking, thus leading to higher weight loss during thermal treatment with respect to unmodified PVC plastisols. This was also confirmed by an evident yellowing after crosslinking, especially at higher temperatures.
Crosslinking of plasticized PVC used in coated fabrics
Journal of Vinyl and Additive Technology, 2009
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-tertbutyl peroxide as an initiator in the presence of 1,1,1trimethylolpropane 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.
Migrability of PVC plasticizers
Polymer Testing, 2008
The ability of different PVC plasticizers to migrate towards a polymer in contact with flexible PVC has been investigated. A procedure based on the monitoring of the plasticizer concentration by infrared spectroscopy has been employed. The mathematical model applied to experimental data has permitted the calculation of average diffusion coefficients and, hence, a comparison among the plasticizers studied (citrates, phthalates and adipates), independent of the geometry of the system employed. Under the test conditions and the probe polymer employed, phthalates seem to be the plasticizers with the lower migration, in contrast to adipates that give the highest migration levels. r
Journal of Applied Polymer Science, 2006
Blends were prepared of poly(vinyl chloride) (PVC) with four different plasticizers; esters of aconitic, citric, and phthalic acids; and other ingredients used in commercial flexible PVC products. The thermal and mechanical properties of the fresh products and of the products after 6 months of aging were measured. Young's modulus of the PVC blends was reduced about 10-fold by an increase in the plasticizer level from 15 to 30 phr from the semirigid to the flexible range according to the ASTM classification, but a 40-phr level was required for PVC to retain its flexibility beyond 6 months. At the 40-phr level, tributyl aconitate performed better than diisononyl phthalate (DINP) or tributyl citrate, in terms of lowering Young's modulus, both in the fresh materials and those aged for 6 months. The effects of the four plasticizers on the glass-transition temperature (T g) were similar, with T g close to ambient temperature at the 30-and 40-phr levels in freshly prepared samples and at 40-608C in those aged for 6 months. The thermal stability of the PVC plasticized with DINP was superior among the group. Overall, tributyl aconitate appeared to be a good candidate for use in consumer products where the alleged toxicity of DINP may be an issue.
Matéria (Rio de Janeiro)
Polyvinyl chloride (PVC) is a very versatile polymer with many applications. Due to the easy incorporation of additives and plasticizers in this resin. The most used plasticizer for PVC is dioctyl phthalate (DOP), however its use has been restricted by several organizations because it presents potential toxicity. In this way, the objective of this work is to evaluate thermal, physical and dynamic-mechanical characteristics for a polymeric plasticizer alternative to DOP, polyisobutene base. As a method of comparison, the contents of the materials were kept constant, and only the plasticizer content of the samples was altered. Results indicated that the PVC compounds obtained satisfactory plasticizing results and that don't have chemical transformations. In addition, the plasticizer evaluated has a higher thermal stability when compared to the compound with DOP, proving to be a promising result.
Materiale Plastice
The topic of this paper refers to the influence of the plasticizer and the processing mode upon the characteristics of the poly(vinyl chloride) (PVC) composites. Thereby, in this study two types of industrial plasticizers were used to highlight their influence upon the properties of final composites. The employed lubricant was stearic acid, the most common and cheapest additive used in the industry for cables manufacturing. For economic reasons, calcium carbonate of 2 m size was used as reinforcing agent. Further on, two sets of samples were prepared, targeting the influence of the processing mode upon the properties of final composites. Beside the structure (by FT-infrared), thermal behavior (thermal analyses and differential scanning calorimetry) and mechanical properties (dynamic mechanical analyses, tensile strength and elongation at break) of PVC composites, the limiting oxygen index (LOI) and the overall morphology of the samples were also investigated.
Thermal decomposition behaviour of crosslinked plasticized PVC
Polymer Degradation and Stability, 1999
Thermal stability and thermal decomposition behaviour of plasticized PVC poly (vinyl chloride) and crosslinked plasticized PVC ®lms has been studied. Two eective crosslinking agents have been used: the sodium salt of g-mercaptopropyltrimethoxysilane (MSi) and g-aminopropyltriethoxysilane (ASi). Clear dierences have been observed in the thermogravimetric behaviour of the dierent samples. MSi crosslinked ®lms show a certain delay in the decomposition process as compared to plasticized PVC as well as three clear decomposition processes, probably involving the plasticizer and dierent fractions produced in the crosslinking reactions. In the case of the ®lms prepared with ASi a single decomposition stage is observed at temperatures much lower than those obtained in the other PVC ®lms studied, showing the strong in¯uence of this compound in the thermal behaviour of plasticized PVC.
Thermal and mechanical properties of bio-based plasticizers mixtures on poly (vinyl chloride)
Polímeros
The use of mixtures of nontoxic and biodegradable plasticizers coming from natural resources is a good way to replace conventional phthalates plasticizers. In this study, two secondary plasticizers of epoxidized sunflower oil (ESO) and epoxidized sunflower oil methyl ester (ESOME) were synthesized and have been used with two commercially available biobased plasticizers; isosorbide diesters (ISB) and acetyl tributyl citrate (ATBC) in order to produce flexible PVC. Different mixtures of these plasticizers have been introduced in PVC formulations. Thermal, mechanical and morphological properties have been studied by using discoloration, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), tensile-strain and scanning electron microscopy (SEM). Studies have shown that PVC plasticization and stabilization were improved by addition of plasticizers blends containing ISB, ATBC, ESO and ESOME. An increase in the content of ESO or ESOME improved thermal and mechanical properties, whereas ESOME/ATBC formulations exhibited the best properties.