Effect of conducting carbon black on the photostabilization of injection molded poly(propylene-co-ethylene) containing TiO2

Maia, Dênison R. J.; Balbinot, L.; Poppi, Ronei J.; Paoli, M-A. De

doi:10.1016/s0141-3910(03)00168-x

Cited by 11 publications

(6 citation statements)

References 26 publications

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“…This multivariate tool was successfully applied to chemical analysis problems using atomic emission spectroscopy and atomic X‐ray spectrometry (47) and to diagnose calibration problems in atomic absorption spectroscopy (48). Besides these applications, its potentialities have been shown in the polymer degradation (49), soil classification using near infrared spectroscopy (50), modeling toxicity (51), design of novel trypanocidal quinones compounds (52), among others (53).…”

Section: Methodsmentioning

confidence: 99%

Artificial Neural Networks and the Study of the Psychoactivity of Cannabinoid Compounds

et al. 2010

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Cannabinoid compounds have widely been employed because of its medicinal and psychotropic properties. These compounds are isolated from Cannabis sativa (or marijuana) and are used in several medical treatments, such as glaucoma, nausea associated to chemotherapy, pain and many other situations. More recently, its use as appetite stimulant has been indicated in patients with cachexia or AIDS. In this work, the influence of several molecular descriptors on the psychoactivity of 50 cannabinoid compounds is analyzed aiming one obtain a model able to predict the psychoactivity of new cannabinoids. For this purpose, initially, the selection of descriptors was carried out using the Fisher's weight, the correlation matrix among the calculated variables and principal component analysis. From these analyses, the following descriptors have been considered more relevant: E LUMO (energy of the lowest unoccupied molecular orbital), Log P (logarithm of the partition coefficient), VC4 (volume of the substituent at the C4 position) and LP1 (Lovasz-Pelikan index, a molecular branching index). To follow, two neural network models were used to construct a more adequate model for classifying new cannabinoid compounds. The first model employed was multi-layer perceptrons, with algorithm back-propagation, and the second model used was the Kohonen network. The results obtained from both networks were compared and showed that both techniques presented a high percentage of correctness to discriminate psychoactive and psychoinactive compounds. However, the Kohonen network was superior to multi-layer perceptrons.

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Section: Methodsmentioning

confidence: 99%

Artificial Neural Networks and the Study of the Psychoactivity of Cannabinoid Compounds

et al. 2010

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“…Mixed filler system of titania with conducting carbon black was also reported to enhance the photostability of injection molded poly(propyleneco-ethylene) polymer. 57 As they act via different mechanisms and this is to be expected. The search for better and lower cost light stabilizers and polymer types that are inherently photostable in sunlight is an on-going process.…”

Section: Recent Developments In Halsmentioning

confidence: 98%

Effects of stratospheric ozone depletion and climate change on materials damage

Andrady

Hamid

Torikai³

2007

Photochem Photobiol Sci

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Nanoscale inorganic fillers with average particle sizes smaller by an order of magnitude or more compared to those of conventional fillers are becoming commercially available. The efficacy of these fillers used in polymer formulations and particularly their effect as photostabilizers are beginning to be investigated. These may enhance or retard photodegradation depending on the surface coating of the particles or their chemical nature. Some recent data indicate their use as effective photostabilizers in some common polymers. However, the potential deleterious interaction of the nanoscale fillers with other additives in the formulation has also been pointed out. Depending on the efficiency of stabilization and the economics of their use nanofillers may provide a useful route to UV-stabilization of plastics and rubber used outdoors. Insufficient data are available at this time to assess their potential impact on material and coatings stabilization. Organic fillers such as lignocellulose continue to be investigated for outdoor applications. Their cost advantage makes them attractive despite the somewhat reduced engineering properties of their composites. Recent reports, however, suggest the photostability of these composites to depend on the source of fiber as well as the processing techniques employed in fabricating products from them. Identification of the key determinants in terms of species, isolation and processing of polymer-wood composites is critical to developing them for long-term outdoor use. Efforts are continuing on the synthesis of new light stabilizers, particularly those based on a hindered amine light stabilizers (HALS), and on identifying synergistic combinations of known stabilizers for common thermoplastics. Variants of HALS-type stabilizers that reduce the loss of stabilizer via leaching or migration were recently reported. Studies on the permanence of the stabilizers themselves when exposed to solar UV wavelengths have also been reported in recent work. Identification of relevant mechanisms is important not only to understand the interactions of climate changes and higher UV solar environments with materials damage, but also to guide future design of light-stabilizers.

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“…These results indicate the variations of the red, green and blue colour components. Colour fading during the use of polymer products is one of the main reasons for shortening lifetime and may occur due to (i) the formation of chromophore groups, like carbonyl and hydroperoxide, within the polymer molecule 32 ; (ii) surface cracking, that leads to the reflection of all wavelength and thus reduces the selectivity in light absorption and causes whitening 14 ; and (iii) changes in pigment molecule chemical structure that lead to colour shifting 8 . The combination of these effects is shown in the variation of RGB colour components of Figure 4.…”

Section: Colorimetrymentioning

confidence: 99%

“…Even though these effects of pigments are extremely important from the practical point of view, the scientific literature gives very little attention to the influence of these additives on the degradation (and stabilization) of polymers. Most of the work was developed on carbon black 14,15 or white pigments 13,[16][17][18] and very little with colour products [19][20][21] . When pigmented products contain photo stabilizers, synergic and antagonic effects may occur [22][23][24] and, hence, the need for investigation on this field is even more important.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Red Pigment and Photo Stabilizers on the Photo Degradation of Polypropylene Films

Cavalcanti

Rabello

2019

Mat. Res.

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The aim of this work was to evaluate the photo degradation of PP films containing photo stabilizers, a ultraviolet absorber and a hindered amine light stabilizer (HALS), and a red pigment. The films were produced by extrusion and exposed to the UV radiation in the laboratory for up to 15 weeks. The results obtained from FTIR, UV-vis and colorimetry showed that the pigment reduced the rate of chemical degradation both in non-stabilized and photo stabilized films, and the influence was more significant for the combination of pigment and HALS. However, the color shift was more evident when the pigment was present, suggesting that this additive may suffer chemical rearrangements during exposure but do not generate free radicals that can initiate degradation of the polymer. The mechanical properties of the films followed the same trend as the other results, but the unexposed films showed a peculiar behaviour, with much higher tensile strength when the pigments were present. X-ray diffraction and DSC analyses suggested that this might be related to differences in crystal structure.

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Effect of conducting carbon black on the photostabilization of injection molded poly(propylene-co-ethylene) containing TiO2

Cited by 11 publications

References 26 publications

Artificial Neural Networks and the Study of the Psychoactivity of Cannabinoid Compounds

Artificial Neural Networks and the Study of the Psychoactivity of Cannabinoid Compounds

Effects of stratospheric ozone depletion and climate change on materials damage

The Effect of Red Pigment and Photo Stabilizers on the Photo Degradation of Polypropylene Films

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