Search Results
Abstract
Polyvinyl chloride (PVC)/organic-montmorillonite composites were prepared by melt intercalation. Their structures and properties were investigated with X-ray diffraction (XRD), differential scanning calorimetry (DSC) and mechanical testing. The results showed that PVC chains could be intercalated into the gallery of organically modified montmorillonite to form exfoliated PVC/organic-montmorillonite nanocomposites, and the glass transition temperatures of PVC/organic-montmorillonite composites were lower than that of neat PVC. However, the tensile strength, and both the Izod type and Charpy notched impact strengths of PVC/organic-montmorillonite nanocomposites were fitted with the linear expressions: t=535.07-6.39T g, s I=378.76-4.59T g and sC=276.29-3.59T g, respectively.
Abstract
The thermal degradation of a sort of polyvinyl chloride was investigated. Complex processes for polyvinyl chloride degradation were evidenced. The kinetic analysis of dehydrochlorination and of subsequent processes was carried out. A change of mechanism was detected when dehydrochlorination goes to completion. The values of non-isothermal kinetic parameters determined by various methods are in a satisfactory agreement. The obtained results allowed some clarifications concerning the thermal degradation steps.
Abstract
The phase behavior of several polycarbonate homopolymers and copolymers blended with PVC and chlorinated PVCs (CPVCs) has been investigated. Tetrachlorobisphenol-A polycarbonate (TCPC) is miscible in all proportions with PVC and CPVCs containing up to70.2 wt% chlorine. CPVCs having chlorine contents greater than 70.2% (by weight) are immiscible with TCPC. Tetrabromobisphenol-A polycarbonate (TBPC) exhibits phase mixing with PVC and CPVCs; however, the high T g of this polycarbonate (260°C) prevents adequate investigation of equilibrium phase behavior. Bisphenol-A polycarbonate (BPC), tetramethylbisphenol-A polycarbonate (TMPC), and hexafluorobisphenol-A polycarbonate (HFPC) form two-phase mixtures with the vinyl polymers. Microstructural differences in the CPVCs due to chlorination method (solution chlorination vs. slurry chlorination) have no effect on the miscibility results. Miscibility was observed in several copolycarbonate/CPVC blends and was found to be dependent on copolymer composition. Using a binary interaction, mean-field theory, segmental interaction parameters were estimated for repeat unit interactions. Based on the estimated interaction parameters, miscibility in these blends is primarily the result of intramolecular repulsive effects, rather than strong intermolecular attractive forces.
Abstract
Positron lifetime measurements in polyvinyl chloride (PVC), plasticized with the aid of dibutyl phthalate and tricresyl phosphate have been made. The plasticizers, the first range plasticizers, are an organic and an inorganic ester, respectively. The influence of the different concentration of the plasticizer in the PVC on positron lifetimes in the polymer have been investigated. A conventional fast-slow coincidence lifetime spectrometer with plastic scintillators has been used for the lifetime measurements. All the measurements have been performed in air, at room temperature. Mean free volumes radii have been calculated from the lifetime data.
Thermal and photochemical stability of polystyrene and its blends with polyvinyl chloride
II Photochemical transformation in polystyrene blends with polyvinyl chloride, and their thermal stability
The influence of some irregularities in polystyrene (PS) and polyvinyl chloride (PVC) chains on their thermal stability was investigated. UV irradiation caused an increase in the content of these irregularities in the polymers. It was found that the presence of carbonyl groups and crosslinking of the polymer chains hamper the thermal dehydrochlorination of PVC and the total decomposition of both polymers. On the other hand, weak peroxy linkages (which facilitate degradation processes) and conjugated double bonds decrease the temperature of total decomposition of PS and PVC blends.
Thermal and photochemical stability of polystyrene and its blends with polyvinyl chloride I.
Influence of small amount of PVC in PS films on their thermal parameters
Abstract
This biomaterials overview for selecting polymers for medical devices focuses on polymer materials, properties and performance. An improved understanding of thermoplastics and thermoset properties is accomplished by thermal analysis for device applications. The medical applications and requirements as well as the oxidative and mechanical stability of currently used polymers in devices are discussed. The tools used to aid the ranking of the thermoplastics and thermosets are differential scanning calorimetry (DSC), thermogravimetry (TG), thermal mechanical analysis (TMA) and dynamic mechanical analysis (DMA) as well as a number of key ASTM polymer tests. This paper will spotlight the thermal and mechanical characterization of the bio-compatible polymers e.g., olefins, nylon, polyacetals, polyvinyl chloride and polyesters.
), polyvinyl chloride (PVC), Göynük oil shale, and polymer/oil shale blends were investigated under air atmosphere using a thermogravimetric analyzer to obtain an overall understanding of the interaction of oil shale and polymers. The combustion kinetic data
meets all existing standards including ISO5660 and ASTM E1354. The cone is a Standard Cone Calorimeter from Fire Testing Technology Limited, UK. The tested materials were two kinds of polyvinyl chloride (PVC) wall panel, glass
Kinetics of thermal degradation of poly(vinyl chloride)
Thermogravimetry and spectroscopy
. 6. Fox , VW , Hendricks , JG , Ratti , HJ . Degradation and stabilization of polyvinyl chloride . Ind Eng Chem . 1949 ; 41 : 8 1774 – 1779 . 10.1021/ie50476a060 . 7
