Physical, Chemical, and Thermal Analysis of Thermoplastic Resins

This article addresses some established protocols for characterizing thermoplastics and whether they are homogeneous resins, alloyed, or blended compositions or highly modified thermoplastic composites. It begins with a discussion on characterizing mechanical, rheological, and thermal properties of polymer. This is followed by a section describing molecular weight determination using viscosity measurements. Next, the article discusses the use of cone and plate and parallel plate geometries in melt rheology. It then reviews the processes involved in the analysis of thermoplastic resins by chromatography. Finally, the article covers three operations of thermoanalysis, namely differential scanning calorimetry, thermogravimetric analysis, and thermomechanical testing.

Star-Shaped Polydimethylsiloxanes with Organocyclotetrasilsesquioxane Branching-Out Centers: Synthesis and Properties

New non-crystallizable low-dispersity star-shaped polydimethylsiloxanes (PDMS) containing stereoregular cis-tetra(organo)(dimethylsiloxy)cyclotetrasiloxanes containing methyl-, tolyl- and phenyl-substituents at silicon atoms and the mixture of four stereoisomers of tetra[phenyl(dimethylsiloxy)]cyclotetrasiloxane as the cores were synthesized. Their thermal and viscous properties were studied. All synthesized compounds were characterized by a complex of physicochemical analysis methods: nuclear magnetic resonance (NMR), FT-IR spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), viscometry in solution, rheometry, and Langmuir trough study.

EFFECT OF ETHYLENE OXIDE STERILIZATION ON PLASTISIZER MIGRATION AND MECHANICAL AND BLOOD PROPERTIES OF MEDICAL GRADE POLYVINYLE CHOLORIDE

The use of phthalates as a plasticizer in plasticized polyvinyl chloride (PVC) always poses the threat of migration of phthalates into the environment through medical equipment. Phthalates can be used with natural-based plasticizers, such as Epoxidized soybean oil (ESBO) known as phthalate’s scavenger and PVC stabilizers. PVC formulations were characterized by different combinations of di (2-ethylhexyl) phthalate (DEHP) 30-40% with 5% ESBO. PVC flexibility increased significantly in the presence of ESBO, without a change in strength (tensile test). The decrease of the Tg temperature by adding ESBO in Differential Scanning Calorimetry indicated that ESBO preserved DEHP in the polymer. Also, it was shown that the sterilization process with Ethylene Oxide, similar to ESBO, decreased the Tg of polymer. DEHP migration was evaluated at a maximum level to the environment using the Gas Chromatography test. Samples containing ESBO showed less hemolysis. ABSTRAK: Penggunaan phthalates sebagai plasticizer dalam plastik polyvinyl chloride (PVC) selalu menimbulkan ancaman penghijrahan phthalates ke alam sekitar melalui peralatan perubatan. Phthalates boleh digunakan dengan plasticizer berasaskan semula jadi, seperti minyak kacang soya Epoxidized (ESBO) yang dikenali sebagai pemulung phthalate dan penstabil PVC. Formulasi PVC dicirikan oleh kombinasi yang berbeza di (2-ethylhexyl) phthalate (DEHP) 30-40% dengan 5% ESBO. Fleksibiliti PVC meningkat dengan ketara di hadapan ESBO, tanpa perubahan kekuatan (ujian tegangan). Penurunan suhu Tg dengan menambahkan ESBO dalam Calorimetri Pengimbasan Berbeza menunjukkan bahawa ESBO mengekalkan DEHP dalam polimer. Juga, ditunjukkan bahawa proses pensterilan dengan Etilena Oksida, serupa dengan ESBO, menurunkan Tg polimer. Penghijrahan DEHP dinilai pada tahap maksimum ke lingkungan menggunakan uji Kromatografi Gas. Sampel yang mengandungi ESBO menunjukkan kurang hemolisis.

Combined effect of Sn addition and pre-ageing on natural secondary and artificial ageing of Al–Mg–Si alloys

Both Sn addition and pre-ageing are known to be effective in maintaining the artificial ageing potential after natural ageing of Al–Mg–Si alloys. In this study, the combined effects of Sn addition and pre-ageing at 100 °C or 180 °C on natural secondary ageing and subsequent artificial ageing of an alloy AA6014 were investigated using hardness, electrical resistivity, differential scanning calorimetry and transmission electron microscopy characterizations. It is found that pre-ageing can suppress natural secondary ageing and improve the artificial ageing hardening kinetics and response after 1 week of natural secondary ageing in both alloys with and without Sn addition. The effect of pre-ageing at 100 °C is more pronounced in the Sn-free alloy while the combination of pre-ageing at 180 °C and adding Sn shows superiority in suppressing natural secondary ageing and thus avoiding the undesired hardening before artificial ageing. Moreover, when natural ageing steps up to 8 h are applied before pre-ageing at 100 °C, the effect of pre-ageing in Sn-added alloy can be further improved. The influence of Sn on vacancies at different ageing temperatures is discussed to explain the observed phenomena. Graphical abstract

Determination of thermophysical properties of prototypes of tin-lithium alloy by differential scanning calorimetry

This paper presents a description of research works to determine the thermophysical properties of a tin-lithium alloy with a different percentage of lithium and tin atoms in the alloy. The method of differential scanning calorimetry (DSC) was used for the studies, by which the thermophysical properties of the alloy (temperature of phase transition and enthalpy) were determined. The work was carried out at the TiGrA experimental complex. Studies to determine the enthalpy and temperature of phase transition of prototypes of tin-lithium alloy were carried out in the temperature range from 150°C to 500°C at a heating rate of 10°C/min. The experiments were carried out with a pristine sample of tin (reference) and prototypes of a tin-lithium alloy, the percentage of lithium in which was 20, 25 and 27 at. %. As a result of the work performed, the melting point of the prototypes was determined, which was 224°C and 218°C. The values of the specific heat of fusion (enthalpy) of the investigated alloys were determined, which amounted to 76.5 J/g, 80.7 J/g and 86.3 J/g, respectively.