Synthesis and characterization of the cross-linked polyurethane–gum arabic blends obtained by multiacrylates cross-linking polymerization

2012 ◽  
Vol 45 (6) ◽  
pp. 564-576 ◽  
Author(s):  
Stefan Oprea ◽  
Veronica Oprea
Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 721 ◽  
Author(s):  
Jorge A. Ramírez-Gómez ◽  
Javier Illescas ◽  
María del Carmen Díaz-Nava ◽  
Claudia Muro-Urista ◽  
Sonia Martínez-Gallegos ◽  
...  

Atrazine (ATZ) is an herbicide which is applied to the soil, and its mechanism of action involves the inhibition of photosynthesis. One of its main functions is to control the appearance of weeds in crops, primarily in corn, sorghum, sugar cane, and wheat; however, it is very toxic for numerous species, including humans. Therefore, this work deals with the adsorption of ATZ from aqueous solutions using nanocomposite materials, synthesized with two different types of organo-modified clays. Those were obtained by the free radical polymerization of 4-vinylpyridine (4VP) and acrylamide (AAm) in different stoichiometric ratios, using tetrabutylphosphonium persulfate (TBPPS) as a radical initiator and N,N′-methylenebisacrylamide (BIS) as cross-linking agent. The structural, morphological, and textural characteristics of clays, copolymers, and nanocomposites were determined through different analytical and instrumental techniques, i.e., X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Adsorption kinetics experiments of ATZ were determined with the modified and synthesized materials, and the effect of the ratio between 4VP and AAm moieties on the removal capacities of the obtained nanocomposites was evaluated. Finally, from these sets of experiments, it was demonstrated that the synthesized nanocomposites with higher molar fractions of 4VP obtained the highest removal percentages of ATZ.


e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Ying Wu ◽  
Qing Yang ◽  
Yali Gi ◽  
Yueting Zhang

AbstractA novel hydrogel wound dressing with semi-interpenetrating polymer network structure (semi-IPN) was prepared by radical polymerization of acrylic acid with potassium persulfate (K2S2O8) as initiator and N, N'-methylenebisacrylamide (MBA) as cross-linking agent in the presence of chitosan (CTS) and polyvinyl pyrrolidone (PVP). Hydrogels were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM displayed semi- IPN hydrogels' creased surface with some scale-like wrinkles, thus improving the absorptive capability which has been considered as a most important characteristic of wound dressings. It was found that the content of cross-linking agent and the mass ratio of PVP and CTS had much influence on the mechanical properties of the hydrogel, varying from brittle plastics to elastomer due to the different degrees of cross linking. Since tensile strength is partly in inverse ratio to the hydrogel absorbent capability, the article offers an analysis of varying material proportion in order to obtain an optimum properties of the hydrogel wound dressing .


2014 ◽  
Vol 2 (42) ◽  
pp. 7429-7439 ◽  
Author(s):  
Anuj Kumar ◽  
Sabindra K. Samal ◽  
Rupesh Dash ◽  
Umaprasana Ojha

The synthesis and characterization of a series of injectable and stimuli responsive hydrogels based on polyacryloyl hydrazide have been accomplished using dimethyl 2,2′-thiodiacetate, acrylic acid, diethyl malonate and polyethylene glycol diacrylate as cross-linkers through a chemical or dual cross-linking pathway.


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