Thermal Characteristics Of Polymers Research Articles

A real time detection of polymer type in polymeric materials using fluorescent properties and image processing technique

Identification of polymer type in unknown samples is an important issue in industry, which is accomplished using experimental methods such as spectrophotometric and microscopic methods, as well as measuring the physical and thermal characteristics of polymer. On the other hand, when it comes to industrial level and large sample sizes, aforementioned methods are laborious and costly. A common method to tackle the problem is to use chemical solvents and substances. Substantial use of chemicals, on the other hand, may lead to serious health and environmental issues. Therefore, the aim of this study is to introduce a promising clean, fast and facile approach in identification of polymeric materials that enables industry to bridge traditional process with predictive power of software tools. A special focus has been done on textile polymeric fibers and yarns. To address described issues, polymeric materials have been irradiated under ultraviolet (UV) light source. As a result, an augmented color difference appears between different polymer types, because of their different fluorescent activity. Created color difference was then, detected using a digital camera sensor, which works based on principals of image processing technique in python environment. Experimental observations showed good potential of using optical tools in polymer detection approaches.

Novel Multicolor Schiff Base Polymers Prepared via Oxidative Polycondensation.

A series of diimine Schiff bases and their polymers were synthesized via the oxidative polycondensation reaction. The structures of the compounds were confirmed by (1)H-NMR, (13)C-NMR, FT-IR and UV-vis spectral measurements. Electrochemical and optical band gap values of synthesized compounds were determined by cyclic voltammetry (CV) and UV-vis measurements, respectively. Fluorescence measurements of the compounds were conducted in various solvents. The effects of solution concentration on the fluorescence spectra were investigated and quantum yield was calculated for the polymer of 5-(diethylamino)-2-(biphenylmethylene) hydrazonomethylphenol (PDEAHP). According to fluorescence measurements, the quantum yield of PDEAHP was found as 16% in DMF solution. Thermal characteristics of polymers were studied by TG-DTA and DSC analyses.

Assessment of Nanocatalyst Dispersibility in a Polymer by Employing Relative Standard Deviation

A relative standard deviation (RSD) method has been developed to evaluate the nanocatalyst dispersibility in an energetic polymer. The dispersibility of nanocatalyst and thermal characteristics of the polymer exhibits high dependence on the RSD of the concentration distributions of nanocatalyst. The improvement of the dispersibility of nanocatalyst, which is dependent on kneading time, can be presented by a decrease in the RSD of the concentration distributions. Moreover, the decomposition temperature and the combustion heat of the polymer is reduced gradually and enhanced distinctly, respectively, with the decrease of the RSD of the nanocatalyst distributions. However, over-kneading may lead to a reunion of nanocatalyst and a decline of thermal characteristics of the energetic polymer, and presented with an increasing of the RSD of the concentrations of nanocatalyst. The optimal kneading time is 3 h and an acceptable value of the RSD is approximately 1% of the concentration distributions of nanocatalyst for the energetic polymer with nanometer copper oxide catalyst.

Alteration of Thermal Characteristics of Polymer for the Purpose of Creating a Two-Stage Shape Memory Polymer

A polymer fabricated by mixing PU soft segment and epoxy bore the thermal characteristics of the melting temperature, Tm, of PU soft segment and the glass transition temperature, Tg, of epoxy. The polymer fabricated even exhibited the shape memory effect at the Tg and Tm. Based on this observation, it was speculated that simply mixing two polymers bearing totally different thermal characteristics each other could result in a two-stage SMP, which could exhibit the shape memory effect at the two distinct temperatures. However, it was actually observed that the two-stage SMP was not always successfully created by that method. But DSC measurements revealed that such an unsuccessfully fabricated SMP still bore the thermal characteristics of its ingredient polymers. Hence, the mixing of appropriate polymers still could result in a new two-stage SMP, and the method of two-polymer-mixing must be still an effective method for creating a two-stage SMP.

Coordinative polymerization of p‐substituted phenyl glycidyl ethers, 1. Effect of electron‐donating groups

AbstractA series of p‐substituted glycidyl phenyl ethersIUPAC nomenclature: 2,3‐epoxypropyl phenyl ether. with electron donor groups was prepared using a multistep synthetic method. These compounds were polymerized using four of the most common aluminium‐based coordinative initiators, (C2H5)3Al/H2O (the Vandenberg catalyst), (C2H5)3Al/CH3COCH2COCH3/H2O (the Vandenberg chelate catalyst), [(CH3)2CHO&]2AlOZnOAl[OCH(CH3)2]2 (the Teyssié catalyst) and [(CH3)2CHO]3AV/ZnCI2 (the Price catalyst), all with different Lewis acid character. The influence of the electron‐donor group on the characteristics and conversion was studied. Generally speaking, both the Vandenberg and the Teyssié catalysts yield mostly an insoluble polymer fraction, whereas the Price catalyst was shown to be the most stereoselective catalyst. Moreover, the Vandenberg chelate catalyst gave the highest molecular weight, the Price catalyst the lowest. Thermal characteristics of polymers were studied by means of differential thermal analysis to obtain glass transition temperatuures, melting temperatures and fusion enthalpies.

The Influence of Chemical Structure on the Thermal Characteristics of Polymers

Abstract The effects of chemical structure on the thermal characteristics of polymers are reviewed.