Benzoxazine monomers based on aromatic diamines and investigation of their polymerization by rheological and thermal methods

2020 ◽  
Vol 138 (10) ◽  
pp. 49974
Author(s):  
Igor A. Sarychev ◽  
Vyacheslav V. Kireev ◽  
Vladimir V. Khmelnitskiy ◽  
Viktoria V. Vorobyeva ◽  
Anton S. Tupikov ◽  
...  
Keyword(s):  
Aromatic Diamines ◽  
Thermal Methods

Synthesis and properties of aromatic polyimides containing oxyalkylene linkages

1995 ◽  
Vol 7 (1) ◽  
pp. 23-40 ◽  
Author(s):  
Mark W Beltz ◽  
Frank W Harris
Keyword(s):  
Glass Transition ◽  
Organic Solvents ◽  
Ethyl Ether ◽  
Amic Acid ◽  
Pyromellitic Dianhydride ◽  
Melting Points ◽  
Aromatic Diamines ◽  
Thermal Methods ◽  
Glass Transition Temperatures ◽  
Aromatic Polyimides

A series of para-catenated aromatic diamines containing oxyalkylene linkages, i.e., i.2-bis(4-aminophenoxy)ethane, bis[2-(4-aminnophenoxy)ethyl]ether, 1,2-bis[24{4-aminio-phenoxy)ethoxyjethane and bis{2-[2A4-aminophenoxy)ethoxy]ethyllether were polymerized with 3,3',4.4'benzophenonetetracarboxylic dianhydride (BTDA) and pyromellitic dianhydride. The poly(amic acid)s obtained were imidized by both chemical and thermal methods. It was postulated that the incorporation of the flexible linkages in the polyimides' backbones would result in solubility in organic solvents and moderate glass transition temperatures (Tg) that would allow the polymers to be melt processed. However, the polyimides were insoluble and highly crystalline with melting points (Tm) above 400"C. In an attempt to disrupt the polymers' symmetry. mixtures of the diamines and 1,3-bis(3-aminophenoxy)benzene were polymerized with BTDA. The resulting copolymers were insoluble and semrnicrystalline with Tm values near 310C. A polyimide with similar properties was obtained by polymerizing a disubstituted diamine, 2,2-diethyl-t,3-bis(4-aminophenoxy)propane, with BTDA. A soluble polymer that could be melt processed was prepared from BTDA and a meta-catenated diamine containing an oxyalkylene linkage, bis[2-(3-aminophenoxy)ethyl)ether. The polymer had a strong Tg near 156 'C and a weak Tm near 240C.

scholarly journals Synthesis and Characterization of Partially Renewable Oleic Acid-Based Ionomers for Proton Exchange Membranes

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 130
Author(s):  
Carlos Corona-García ◽  
Alejandro Onchi ◽  
Arlette A. Santiago ◽  
Araceli Martínez ◽  
Daniella Esperanza Pacheco-Catalán ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Proton Conductivity ◽  
Electrochemical Impedance ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Molar Ratio ◽  
Aromatic Diamines ◽  
Chemical Structures ◽  
Long Chain

The future availability of synthetic polymers is compromised due to the continuous depletion of fossil reserves; thus, the quest for sustainable and eco-friendly specialty polymers is of the utmost importance to ensure our lifestyle. In this regard, this study reports on the use of oleic acid as a renewable source to develop new ionomers intended for proton exchange membranes. Firstly, the cross-metathesis of oleic acid was conducted to yield a renewable and unsaturated long-chain aliphatic dicarboxylic acid, which was further subjected to polycondensation reactions with two aromatic diamines, 4,4′-(hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline and 4,4′-diamino-2,2′-stilbenedisulfonic acid, as comonomers for the synthesis of a series of partially renewable aromatic-aliphatic polyamides with an increasing degree of sulfonation (DS). The polymer chemical structures were confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H, 13C, and 19F NMR) spectroscopy, which revealed that the DS was effectively tailored by adjusting the feed molar ratio of the diamines. Next, we performed a study involving the ion exchange capacity, the water uptake, and the proton conductivity in membranes prepared from these partially renewable long-chain polyamides, along with a thorough characterization of the thermomechanical and physical properties. The highest value of the proton conductivity determined by electrochemical impedance spectroscopy (EIS) was found to be 1.55 mS cm−1 at 30 °C after activation of the polymer membrane.

scholarly journals The Quality of Red Bell Pepper Subjected to Freeze-Drying Preceded by Traditional and Novel Pretreatment

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 226
Author(s):  
Katarzyna Rybak ◽  
Artur Wiktor ◽  
Dorota Witrowa-Rajchert ◽  
Oleksii Parniakov ◽  
Małgorzata Nowacka
Keyword(s):  
Freeze Drying ◽  
Bell Pepper ◽  
Total Phenolic ◽  
Thermal Methods ◽  
Drying Time ◽  
Freeze Dried ◽  
Dehydration Processes ◽  
Vacuum Freezing ◽  
Better Than

It has been demonstrated previously in the literature that utilization of PEF or a combination of a pulsed electric field (PEF) and ultrasounds (US) can facilitate dehydration processes and improve the quality of dried products even better than the application of thermal methods such as blanching. The aim of the study was to evaluate the quality of red bell pepper subjected to freeze-drying preceded by blanching or PEF or US treatment applied in a single and combined mode. Furthermore, the freeze-drying was preceded by shock freezing or vacuum freezing performed inside the freeze-dryer as a result of pressure drop during the first stage of freeze-drying. All of the analyzed technological variants enhanced the drying kinetics when compared to the intact material. Freeze-dried bell pepper subjected to non-thermal pretreatment exhibited higher vitamin C, total phenolic and carotenoids content than blanched material despite the fact that blanching reduced drying time the most compared to all other analyzed methods.

scholarly journals Modeling the production of hard-to-recover oil reserves using thermal methods

2021 ◽  
Vol 1064 (1) ◽  
pp. 012062
Author(s):  
A A Gizzatullina ◽  
T N Minnivaleev ◽  
I Sh Mingulov
Keyword(s):  
Thermal Methods ◽  
Oil Reserves

Nickel-catalysed dehydrogenative coupling of aromatic diamines with alcohols: selective synthesis of substituted benzimidazoles and quinoxalines

2019 ◽  
Vol 55 (42) ◽  
pp. 5958-5961 ◽  
Author(s):  
Atanu Bera ◽  
Motahar Sk ◽  
Khushboo Singh ◽  
Debasis Banerjee
Keyword(s):  
Hydrogen Gas ◽  
Selective Synthesis ◽  
Primary Alcohols ◽  
Aromatic Diamines ◽  
Dehydrogenative Coupling

The nickel-catalysed dehydrogenative coupling of 1,2-di-amino-benzene with primary alcohols and diols for the synthesis of N-heterocycles is reported. The catalytic protocol enables the transformation in up to 91% yield and generates water and hydrogen gas as byproducts.

Evaluation of the aerobic composting process of winery and distillery residues by thermal methods

2007 ◽  
Vol 454 (2) ◽  
pp. 135-143 ◽  
Author(s):  
F.C. Marhuenda-Egea ◽  
E. Martínez-Sabater ◽  
J. Jordá ◽  
A. Sánchez-Sánchez ◽  
R. Moral ◽  
...  
Keyword(s):  
Aerobic Composting ◽  
Thermal Methods ◽  
Composting Process
Sign in / Sign up

Export Citation Format

Share Document