scholarly journals A Process for the Synthesis and Use of Highly Aromatic Organosilanes as Additives for Poly(Vinyl Chloride) Films

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 91
Author(s):  
Safaa H. Mohamed ◽  
Ayad S. Hameed ◽  
Gamal A. El-Hiti ◽  
Dina S. Ahmed ◽  
Mohammed Kadhom ◽  
...  
Keyword(s):  
Vinyl Chloride ◽  
Light Exposure ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Substituted Anilines ◽  
Absorption Bands ◽  
Poly Vinyl Chloride ◽  
Acidic Conditions ◽  
The One

Three organosilanes were synthesized in good yields from the condensation of 4,4′,4″-((phenylsilanetriyl)tris(oxy))tribenzaldehyde and 4-substituted anilines under acidic conditions. The structure of the organosilanes was confirmed using a variety of techniques. Organosilanes were mixed with poly(vinyl chloride) (PVC) and homogenous films were produced. The effect of long-term irradiation on the films containing organosilanes was tested using various methods. Monitoring the infrared spectra of PVC films before, during and after irradiation processes showed the formation of side products comprising polyene, carbonyl and hydroxyl groups. The intensities of absorption bands due to these functional groups were much lower in the presence of organosilanes as compared to the blank film. Also, the decrease in the weight and molecular weight of PVC films after irradiation was lower in the presence of organosilanes. Additionally, there was a minimal surface change of irradiated PVC in the presence of organosilanes. Clearly, organosilanes act as inhibitors, particularly the one containing the hydroxyl group, for the photodegradation of PVC. Different mechanisms were proposed to speculate the role played by organosilanes in stabilizing PVC against long-term ultraviolet light exposure.

scholarly journals Synthesis and biotical activity of bacterial cellulose 6-(2-phthalimidoethanesulfonate)

2020 ◽  
Vol 61 (2) ◽  
pp. 29-36
Author(s):  
Zoya P. Belousova ◽  
Keyword(s):  
Bacterial Cellulose ◽  
Side Reaction ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Cellulose Derivatives ◽  
Wound Surface ◽  
Reaction Products ◽  
Absorption Bands ◽  
Hydroxymethyl Group ◽  
Antibacterial And Antifungal

Bacterial cellulose obtained by culturing Gluconacetobacter sucrofermentans in HS environment was converted to sulfonate derivatives using methane-, toluene- and 2-phthalimidoethanesulfonic acids in pyridine. When the ratio of the starting reagents is 1 : 1, the modification of bacterial cellulose according to the primary hydroxyl group of glucopyranose fragments is most likely. The formation of 6-substituted bacterial cellulose derivatives was observed in the reaction mixture. The IR spectra of the reaction products contain absorption bands, which are specific for (O–SO2) group in the region 1377-1338 cm−1 (as), 1178-1154 cm−1 (s), fragments of the corresponding sulfonic acids, as well as free hydroxyl groups of glucopyranose in the region 3495-3382 cm−1. Bacterial cellulose 2-phthalimidoethanesulfonate was dissolved in pyridine. After drying with a desiccant in a desiccator, it turned into a dense transparent film of brown color. The increased molecular film allows to explain the side reaction occurring between the oxo group and fragments of one of the chains of modified cellulose and the non-substituted hydroxymethyl group. The IR spectrum of bacterial cellulose 6-(2-phthalimidoethanesulfonate) contains absorption bands in the region 1711 cm−1, which are specific for (Ar–CO–O) group, and absorption bands in the region 1618 cm−1, which prove the presence of (CO–NH) group. In order to impart antibiotic properties to the bacterial cellulose 6-(2-phthalimido-ethanesulfonate) film, it was physically modified with clotrimazole. The obtained experimental data showed that the films subjected to treatment with a 1% solution of clotrimazole have antibacterial and antifungal effects and prevent the growth of pathogenic microbiota on the wound surface. The exit rates of clotrimazole from the bacterial cellulose 6-(2-phthalimidoethanesulfonate) film and from the pure bacterial cellulose film differed, but only slightly. 2-Phthalimidoethanesulfonate bacterial cellulose films can be used to form composites of effective wound covering, since in addition to the unique properties of bacterial cellulose itself (low allergenicity and adhesion to the wound surface, high hygroscopicity) they will have a regenerating effect.

Long term behaviour of poly(vinyl chloride) products under soil buried and landfill conditions

1999 ◽  
Vol 28 (7) ◽  
pp. 321-326 ◽  
Author(s):  
I. Mersiowsky ◽  
R. Stegmann ◽  
J. Ejlertsson
Keyword(s):  
Vinyl Chloride ◽  
Poly Vinyl Chloride

scholarly journals The Morphology and Performance of Poly(Vinyl Chloride) Containing Melamine Schiff Bases against Ultraviolet Light

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 803 ◽  
Author(s):  
Gamal El-Hiti ◽  
Mohammad Alotaibi ◽  
Ahmed Ahmed ◽  
Basheer Hamad ◽  
Dina Ahmed ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Vinyl Chloride ◽  
Schiff Bases ◽  
Average Molecular Weight ◽  
Hydroxyl Group ◽  
Force Microscopy ◽  
Polymeric Surface ◽  
Atomic Force ◽  
Poly Vinyl Chloride ◽  
And Performance

Five Schiff bases derived from melamine have been used as efficient additives to reduce the process of photodegradation of poly(vinyl chloride) films. The performance of Schiff bases has been investigated using various techniques. Poly(vinyl chloride) films containing Schiff bases were irradiated with ultraviolet light and any changes in their infrared spectra, weight, and the viscosity of their average molecular weight were investigated. In addition, the surface morphology of the films was inspected using a light microscope, atomic force microscopy, and a scanning electron micrograph. The additives enhanced the films resistance against irradiation and the polymeric surface was much smoother in the presence of the Schiff bases compared with the blank film. Schiff bases containing an ortho-hydroxyl group on the aryl rings showed the greatest photostabilization effect, which may possibly have been due to the direct absorption of ultraviolet light. This phenomenon seems to involve the transfer of a proton as well as several intersystem crossing processes.

scholarly journals Long-Term Effect of Ultraviolet Irradiation on Poly(vinyl chloride) Films Containing Naproxen Diorganotin(IV) Complexes

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2396 ◽  
Author(s):  
Angham G. Hadi ◽  
Emad Yousif ◽  
Gamal A. El-Hiti ◽  
Dina S. Ahmed ◽  
Khudheyer Jawad ◽  
...  
Keyword(s):  
Weight Loss ◽  
Vinyl Chloride ◽  
Ultraviolet Irradiation ◽  
Term Effect ◽  
Direct Absorption ◽  
Poly Vinyl Chloride ◽  
Long Term Effect ◽  
Polymeric Chains ◽  
Surface Morphologies

As poly(vinyl chloride) (PVC) photodegrades with long-term exposure to ultraviolet radiation, it is desirable to develop methods that enhance the photostability of PVC. In this study, new aromatic-rich diorganotin(IV) complexes were tested as photostabilizers in PVC films. The diorganotin(IV) complexes were synthesized in 79–86% yields by reacting excess naproxen with tin(IV) chlorides. PVC films containing 0.5 wt % diorganotin(IV) complexes were irradiated with ultraviolet light for up to 300 h, and changes within the films were monitored using the weight loss and the formation of specific functional groups (hydroxyl, carbonyl, and polyene). In addition, changes in the surface morphologies of the films were investigated. The diorganotin(IV) complexes enhanced the photostability of PVC, as the weight loss and surface roughness were much lower in the films with additives than in the blank film. Notably, the dimethyltin(IV) complex was the most efficient photostabilizer. The polymeric film containing this complex exhibited a morphology of regularly distributed hexagonal pores, with a honeycomb-like structure—possibly due to cross-linking and interactions between the additive and the polymeric chains. Various mechanisms, including direct absorption of ultraviolet irradiation, radical or hydrogen chloride scavenging, and polymer chain coordination, could explain how the diorganotin(IV) complexes stabilize PVC against photodegradation.

Prediction of the long-term outdoor weathering of poly(vinyl chloride)

1993 ◽  
Vol 15 (2) ◽  
pp. 113-117 ◽  
Author(s):  
Jean-Luc Gardette ◽  
Jacques Lemaire
Keyword(s):  
Vinyl Chloride ◽  
Poly Vinyl Chloride ◽  
Outdoor Weathering

Mechanism of Action of Titanium Dioxide Pigment in the Photodegredation of Poly(Vinyl Chloride) and Other Polymers

2001 ◽  
Vol 26 (4) ◽  
pp. 337-374 ◽  
Author(s):  
Terence J. Kemp ◽  
Robin A. McIntyre
Keyword(s):  
Titanium Dioxide ◽  
Vinyl Chloride ◽  
Wide Band ◽  
Transition Metal Ions ◽  
Short Review ◽  
Band Gaps ◽  
Chemical Action ◽  
Alkyd Resins ◽  
Poly Vinyl Chloride

The extensive use of titanium dioxide as a pigment and optical agent in polymers, particularly poly(vinyl chloride), polyethylene and alkyd resins, has prompted many investigations of the various deleterious effects (loss of gloss and mechanical properties, chalking, pinking) of long-term exposure to sunlight of the pigmented polymers. This short review summarises the fundamental semiconductor processes undergone by TiO2 on UV irradiation and the consequent chemical action of the reactive intermediates so generated. It also describes the strategies developed to counteract photodegradation induced by TiO2, in particular its encapsulation in a coating by near-UV transparent metal oxides, such as Al2O3 and SiO2, with wide band gaps. The effects of doping TiO2 with transition metal ions are also noted.

scholarly journals Hydrogen bonding systems in birch bark

2020 ◽  
pp. 189-198
Author(s):  
Л.Л. Леонтьев ◽  
И.Д. Лобок ◽  
В.И. Иванов-Омский ◽  
А.С. Смолин
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Frequency Shift ◽  
Hydroxyl Group ◽  
Birch Bark ◽  
Hydroxyl Groups ◽  
Absorption Bands ◽  
Hydrogen Bond Energy ◽  
Absorption Region ◽  
Oh Groups

Произведено сравнение систем водородных связей во внешнем и внутреннем слоях березовой бересты, в сравнении с водородными связями в высококачественной бумаге и в образце выделенной из древесины целлюлозы. Интервал исследуемых частот от 3000 до 3700 см-1, ограничен областью поглощения гидроксильными ОН-группами, частоты которых наиболее чувствительны к возникновению Н-связей. Для оценки параметров Н-связей проводилась деконволюция полос поглощения ОН-групп гауссовыми компонентами. Для корректного выделения поглощения гидроксильными группамипервоначально деконволюции подвергается весь фрагмент, включающий в себя полосы поглощения как метиленовым, так и гидроксильными группами. В дальнейшем анализировались только параметры контуров деконволюции, относящейся к гидроксильным группам. Принималось, что каждый компонент деконволюции может быть ассоциирован с определенным типом водородной связи. Определялся сдвиг частот компонентов деконволюции относительно собственной частоты колебаний изолированной гидроксильной группы, не охваченной по этой причине водородной связью. Для определения энергии водородных связей использовались литературные данные по корреляции энергии водородной связи с частотным сдвигом. Относительная плотность водородных связей оценивалась по отношению площадей контуров деконволюции. A comparison was made of the hydrogen bond systems in the outer and inner layer of birch bark, as well as a comparison of high-quality paper with a sample of pure pulp. The range of frequencies under study from 3000 to 3700 cm-1 is limited by the absorption region by hydroxyl OH groups, the frequencies of which are most sensitive to the occurrence of H bonds. To estimate the parameters of H-bonds, the absorption bands of OH groups were deconvolved by Gaussian components. In order to correctly isolate the absorption by hydroxyl groups, the entire fragment, whichincludes absorption bands of both methylene and hydroxyl groups, is initially deconvolved. In the future, only the parameters of the deconvolution contours related to hydroxyl groups were analyzed. It was assumed that each component of deconvolution can be associated with a certain type of hydrogen bond. The frequency shift of the components of the deconvolution was determined relative to the natural frequency of vibrations of the isolated hydroxyl group, which is therefore not covered by a hydrogen bond. To determine the energy of hydrogen bonds, we used literature data on the correlation of the hydrogen bond energy with a frequency shift. The relative density of hydrogen bonds was estimated by the ratio of the area of the contours of deconvolution.

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