Tensile Strength Measurements (tensile + strength_measurement)

Distribution by Scientific Domains

Selected Abstracts

Influence of a novel castor-oil-derived additive on the mechanical properties and oxygen diffusivity of polystyrene

Markus Klinger
Abstract Mechanical properties, densities, and oxygen diffusion coefficients have been measured in polystyrene samples (PS) as a function of additive loading. The additive employed is based on castor oil, and is a desirable alternative to phthalates. Tensile strength measurements indicate the additive renders PS stronger at low loadings, i.e. it antiplasticizes the material. In contrast, the additive plasticizes PS at high loadings. Specific volumes and oxygen diffusion coefficients do not show this dual behavior. Rather, one observes a monotonic decrease in density and oxygen diffusivity with an increase in additive loading. This suggests that the larger segmental motions responsible for the macroscopic properties of the polymer are influenced by the additive in a different manner than the local motions and confined changes in free volume that govern the mobility of oxygen. These data indicate that antiplasticization cannot be predicted solely from diffusivity and density measurements and, vice versa, trends in diffusivity cannot be deduced from mechanical measurements alone. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Pervaporation of tertiary butanol/water mixtures through chitosan membranes cross-linked with toluylene diisocyanate,

Smitha Biduru
Abstract Membranes made from 84% deacetylated chitosan biopolymer were cross-linked by a novel method using 2,4-toluylene diisocyanate (TDI) and tested for the separation of t -butanol/water mixtures by pervaporation. The unmodified and cross-linked membranes were characterized by Fourier transform infra red (FTIR) spectroscopy, X-ray diffraction (XRD) studies and sorption studies in order to understand the polymer,liquid interactions and separation mechanisms. Thermal stability was analyzed by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) while tensile strength measurement was carried out to assess mechanical strength. The membrane appears to have good potential for breaking the aqueous azeotrope of 88.2 wt% t -butanol by giving a high selectivity of 620 and substantial water flux (0.38 kg m,2 hr,1). The effects of operating parameters such as feed composition, membrane thickness and permeate pressure on membrane performance were evaluated. Copyright © 2005 Society of Chemical Industry [source]

The importance of gel properties for mucoadhesion measurements: a multivariate data analysis approach

Helene Hägerström
ABSTRACT In this study we used tensile strength measurements and a recently developed interpretation procedure to evaluate the mucoadhesive properties of a large set of gel preparations with diverse rheological properties. Multivariate data analysis in the form of principal component analysis (PCA) and partial least square projection to latent structures (PLS) was applied to extract useful information from the rather large quantities of data obtained. PCA showed that the selected series of gels was heterogeneous. Some groupings could be detected but none of the gels was identified as an outlier. By using PLS we investigated the relations between the rheological properties of a gel and the parameters defining the cohesiveness, as measured with the texture analyser used for the mucoadhesion measurements. The rheological properties proved to be important for the results of both the mucoadhesion and the cohesiveness measurements. Furthermore, by using PLS two different measurement configurations were evaluated and it was concluded that the combination of a relatively small volume of gel and two pieces of mucosa seems to be more appropriate than a large volume of gel in combination with one piece of mucosa. [source]

Preparation and characterization of chitosan/KSF biocomposite film

Aylin Alt
Chitosan,clay biocomposites have been prepared in which KSF-montmorillonite (KSF) is used as filler and diluted acetic acid is used as solvent for dissolving and dispersing chitosan and montmorillonite, respectively. The effect of KSF loadings in biocomposites has been investigated. The characterization with different methods (FTIR, DSC, TGA, SEM, and XRD) on chitosan/KSF biocomposites systems was examined. Morphology and properties of chitosan biocomposites have been studied compared with those of pure chitosan. The FTIR and SEM results indicated the formation of an intercalated-and-exfoliated structure at low KSF content and an intercalated-and-flocculated structure at high KSF content. The thermal stability and the mechanical properties of the composites were also examined by DSC, TGA/DTG, and tensile strength measurements, respectively. The dispersed clay improves the thermal stability of the matrix systematically with the increase of clay loading. Tensile strength of a chitosan film was enhanced until the clay ratio up to 2 wt% and elongation-at break decreased with addition of clay into the chitosan matrix. The XRD results confirmed the intercalation of the biopolymer in the clay interlayer by the decrease of 2, values while the chitosan,clayratio increases. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]