UV absorbers polymeric

The polymeric UV absorbers have potential use as stabilizers for fibers, films, and coatings. Until now sev-... 

The evaporation test had been performed to see the loss of polymeric UV absorbers compared to their counterpart monomeric stabilizers, by placing the films in an air-circulating oven at 80°C for 200 to 1000 h (Fig. 13, 14, and 15). 

Whatever the approach, the result is a difficult-to-analyse system. Such options suit polymer producers better than additive suppliers. Aromatic polymers (PPO) have been mentioned as char-forming FRs. Polymeric UV absorbers, blended in proper proportions with commercial plastics, have potential use as stabilisers for fibres, films and coatings. Several monomeric stabilisers containing a vinyl group were homopolymerised and used as stabilisers for PE, PVC, acrylates, polystyrene, cellulose acetate and several vinyl polymers [55]. 

Polymeric UV absorbers can be used in contact lenses, artificial intraocular lenses, etc. These are made from acrylic polymers. One UV-ab-... 

In principle, emulsified sunscreen products are similar to emollient skin-care products in which some of the emollient Hpids are replaced by uv absorbers. The formulation of an effective sunscreen product generally requites combination of a uvB and a uvA absorber if an SPF above about 12 is desired. Two or more of the sunscreens Hsted in Table 13 normally constitute about one-half of the nonvolatiles found in sunscreen lotions. The other half consists of an em ollient (solvent) and emulsifying and bodying agents. If water-resistant quaUties are desired, polymeric film formers, for example, acrylates—octylacrylamide copolymers [9002-93-1] or water-repellent Hpids, for example, dimetbicone [9006-65-9] are included. 

Similarly, estimation of chemical composition of soluble polymer was also dependent on selectivity of the UV detector. Polymerized acrylonitrile has no significant UV absorbance at 230 and 254 nm. Thus, UV chromatograms were used to estimate amounts of polymerized methylacrylate and styrene In each resin system. The refractometer detector was sensitive to polymerized methylacrylate and styrene, as well as to polymerized acrylonitrile. It was therefore necessary to calculate comonomer contribution to refractometer peak areas In order to estimate concentration of polymerized acrylonitrile. This was done by obtaining a refractometer calibration for all three homopolymers. Quantity of polymerized comonomers measured by UV were then converted to equivalent refractometer peak areas. Peak areas due to polymerized acrylonitrile were then calculated by difference, and used to calculate amount of polymerized acrylonitrile. 

HPLC has also been used for analysing fatty acid mixtures [708] and for the characterisation of fatty acids and their derivatives [709]. Fatty acids are commonly analysed on polymeric RPLC columns. Only multiple unsaturated fatty acids can be detected by UV in HPLC the others require derivatisation into UV-absorbing or fluorescing derivatives. Simultaneous determination of saturated and unsaturated fatty acids (C12-C24) by means of RPLC has been reported [710]. Derivatisation is necessary. 

One of the most important advantages of HPLC over spectrophoto-metric methods lies in its specificity and selectivity due to its separation capability. Through chromatographic separations, the analytes of interest can be detected and quantified without interference from the typical matrix that includes excipients, antioxidants, preservatives, and dissolution media. Ion-pair HPLC was used to monitor the dissolution of pentamidine from EVA sustained-release film where polymeric matrices could create significant bias if a spectrophotometric method were used. Due to their strong UV absorbance, the antioxidants and preservatives (e.g., BHA, BHT, ascorbic acid and propyl gallate) are often the major... 

Monomers with UV-absorbing functionality, such as shown in Figure 1.11 can be copolymerized with norbornene to have the UV-absorber bond to the polymeric backbone. (4-(Bicyclo[2.2.1]hept-5-en-2-ylmethoxy)-2-hydroxyphenyl)phenyl-methanone is prepared by first synthesizing 4-allyl-2-hydroxyphenyl-phenyl-methanone... 

Precolumn derivatization with a solid-phase derivatizing precolumn has also been reported. Xie et al. (43) applied polymeric permanganate oxidations of alcohols and aldehydes for the production of UV-absorb-ing species. 

Add UV-absorbing compounds to a skin moisturizer and you have sunblock lotion. Making a sunblock lotion water resistant, however, is problematic. Upon exposure to water, the surfactants within the lotion help to remove the lotion. Manufacturers generally recommend that you reapply the lotion after swimming. Lotions that minimize the use of surfactants have increased water resistance, but they tend to be oily or greasy. For these reasons, many water-resistant formulas include compounds that polymerize into a nonpolar, water-resistant film that helps to hold the sunscreen agent on the skin when wet. 

Set B Based on the results of set A discussed below, a third set. Set B, was prepared (Table IV). Cyasorb 531 (a benzophenone UV light absorber) was found to be the most effective stabilizer in Set A. It was therefore rerun at an even lower add-on in Set B, and since it was the only UV light absorber included in Set A, a second type of UV absorber, Tinuvin 327 (a benzotriazole) was included in Set B. Two new non-polymeric hindered amine light stabilizers (HALS) Tinuvin 770 and Tinuvin 765 were also evaluated in Set B with the hope that they might be more effective than the polymeric HALS (Chimassorb 944LD) included in Set A which was quite detrimental to the heat stability. Combinations of these four additives were also applied in Set B. The three new compounds evaluated have been reported to be effective light stabilizers for polyester and polyamide fibers (Capocci, G., Ciba Geigy Corporation, Ardsley, NY, personal communication, 1986). 

Use Stabilizer polymerization catalyst UV absorbent reagent and intermediate. 

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