Chemisorption and physical adsorption of light stabilizers on pigment and ultrafine particles in coatings

Haacke, G.; Longordo, E.; Brinen, J. S.; Andrawes, Fikry F.; Campbell, B. H.

doi:10.1007/bf02697890

Cited by 28 publications

(17 citation statements)

References 6 publications

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“…It reduces the UV intensity, it happened because of that electrons absorb the energy from UV light and then jump from a valence band to an empty conduction band with the creation of a positive hole in the valence band and mobile or trapped electrons in the conduction band. A fast charge recombination of positive holes and electrons in the conduction band will quench the charge‐separated state of nano‐ZnO particles and decay the destructive energy of UV radiation .…”

Section: Resultsmentioning

confidence: 99%

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Degradation and stabilization of an aromatic polyurethane coating during an artificial aging test viaFTIR spectroscopy

Rashvand

Ranjbar

2012

Materials & Corrosion

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In this investigation nano‐zinc oxide‐containing polyurethane‐based coatings were prepared by incorporating 3 wt% nano‐ZnO in the electrocoating composition. The paint films were deposited on phosphated steel panels through electrodeposition. The films were then rinsed by DI water and baked for 20 min at 165 °C in an electrical laboratory oven. The cured films were exposed to ultraviolet (UV) radiation under humid condition. Variation of chemical nature, color, surface roughness, gloss, and corrosion resistance of the coatings were investigated as a function of UV exposure period. It was found that in presence of nano‐ZnO particles, photodegradation reactions of the aromatic polyurethane network are delayed for a longer time. Specular gloss and surface roughness values of the exposed films are in accordance to this observation too. It was found that deep cracks are formed in the films in which no nano‐ZnO is present. The higher electrical resistance value of the nano‐ZnO stabilized films was found to be due to the protective effect of the particles against photodegradation of the polyurethane binder.

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Section: Resultsmentioning

confidence: 99%

“…As a result, nano‐ZnO particles have become a candidate as a formulating material for UV protection. Since they are inorganic they have additional advantages of being stable and non‐migratory within the applied coating, thus allowing them to potentially offer better effectiveness and a longer service life .…”

Section: Introductionmentioning

confidence: 99%

Degradation and stabilization of an aromatic polyurethane coating during an artificial aging test viaFTIR spectroscopy

Rashvand

Ranjbar

2012

Materials & Corrosion

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“…However, due to their relatively low molecular weight, these additives can migrate out of applied coatings, either to the coating surface or into the substrate. [6][7][8] Also, because they are organic, they are susceptible to a number of degradation mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Assessment of UV-permeability in nano-ZnO filled coatings via high throughput experimentation

et al. 2008

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The degree of UV protection afforded by nano-ZnO in a polyurethane/acrylic clear topcoat was investigated. The influence of nano-ZnO concentration and dry film thickness on the optical properties (e.g., UV permeability and visible transmittance) of the coating was probed using a library of 28 samples that were prepared by high throughput techniques. A model for predicting the UV permeability of nanoZnO filled coatings was developed and the nano-ZnO loading condition required to block >99% UV radiation was determined to be 2.0 g/m 2 . This model can be used to assist in the development of coatings and other polymeric systems embedded with nano-ZnO to protect the coating and underlying materials (i.e., substrate) from UV degradation.

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“…As a consequence, a part of HAS (even LMW) is present in a nonextractable form fully hindering any migration. Some filler-catalyzed hydrolysis of the ester bonds in type 2 HAS was observed, together with the formation of amine salts of type 8 [41]. There is generally a lack of information about interferences of commercial fillers of different origin with HAS.…”

Section: Has In Contact With Fillers and Colorantsmentioning

confidence: 96%

Exploitation of the complex chemistry of hindered amine stabilizers in effective plastics stabilization

Pospı́šil

Pilař

Nešpůrek

2007

Vinyl Additive Technology

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Hindered amine stabilizers (HAS) remain a prominent class of stabilizers having a fortunate development with continuous interest in shaping the future properties of plastics: increase in polymer durability, application extension, reaching new effects. Commercial tests provided much information. Insufficient mechanistic interpretations of the complex effects of environmental factors (harshness of testing, penetration of radiation and oxygen, superposition of temperature, atmospheric impurities) and those of the microenvironment (morphology of the polymer matrix, physical relations of HAS-polymer, interference between HAS and other additives) are a drawback. Model experiments complement commercial studies and explain some phenomena. A careful transfer of information from model experiments must be done to avoid misinterpretation of mechanisms, particularly of the HAS regenerative cycle. A critical analysis of primary steps of the HAS activity mechanism in the polymer matrix based on HAS-related primary nitroxides, formation of their stationary concentration and concentration gradients influenced by polymer morphology, spatial competition between autoreactions, and oxidation of polymerdeveloped alkyl radicals and their scavenging by nitroxides (the key process of HAS efficiency) is outlined. Cyclic regeneration of nitroxides affected by the structure of the amino moiety in the HAS molecule, influence of acid environment, atmospheric ozone or singlet oxygen, cooperative mixtures of HAS with UV absorbers, combinations with additives increasing the thermal stabilization effect and improving color retention, assessment of the heat stabilization performance of HAS by proper testing, and influence of the molecular weight of HAS are mentioned together with examples of the chemical consumption of HAS in the final phases of their lifetime.

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Chemisorption and physical adsorption of light stabilizers on pigment and ultrafine particles in coatings

Cited by 28 publications

References 6 publications

Degradation and stabilization of an aromatic polyurethane coating during an artificial aging test viaFTIR spectroscopy

Degradation and stabilization of an aromatic polyurethane coating during an artificial aging test viaFTIR spectroscopy

Assessment of UV-permeability in nano-ZnO filled coatings via high throughput experimentation

Exploitation of the complex chemistry of hindered amine stabilizers in effective plastics stabilization

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