The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Jinghua Yin - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of amphiphilic polycyclooctene-graft-poly(ethylene glycol) copolymers by ring-opening metathesis polymerization
Reactive and Functional Polymers, 2010Co-Authors: Hengchong Shi, Ligang Yin, Dean Shi, Shifang Luan, Jie Zhao, Jinghua YinAbstract:Abstract In this paper, a novel monomer of 4-methyl-3-(carbamate)–carbanilic acid-4-cyclooctene ester (MCCCE) was synthesized and characterized by FTIR, NMR and ESI-MS. Polycyclooctene-graft-blocked Isocyanate copolymers were prepared by the copolymerization of MCCCE and cyclooctene via ring-opening metathesis polymerization (ROMP). Amphiphilic polycyclooctene-graft–PEG copolymers were prepared by melt mixing the polycyclooctene-graft-blocked Isocyanate copolymers with poly(ethylene glycol) (PEG) at 200 °C. The blocked Isocyanate Group on MCCCE can be dissociated to produce free Isocyanate Group, which will react with the end hydroxyl Groups on PEG molecules. The effects of monomer-to-catalyst, monomer-to-chain transfer agent ratios on molecular weight of the copolymer were detailedly studied. The water contact angle of polycyclooctene-graft–PEG copolymer is much smaller than that of polycyclooctene.
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Preparation of a blocked Isocyanate compound and its grafting onto styrene-b-(ethylene-co-1-butene)-b-styrene triblock copolymer
European Polymer Journal, 2009Co-Authors: Ligang Yin, Yanlong Liu, Jinghua YinAbstract:The epsilon-caprolactam was used to block the Isocyanate Group to enhance the storage stability of allyl (3-Isocyanate-4-tolyl) carbamate. The spectra of FTIR and NMR showed that blocked allyl (3-Isocyanate-4-tolyl) carbamate (BTAI) possesses two chemical functions, an 1-olefin double bond and a blocked Isocyanate Group. The FTIR spectrum showed BTAI could regenerate Isocyanate Group at elevated temperature. DSC and TG/DTA indicated the minimal dissociation temperature was about 135 degrees C and the maximal dissociation rate appeared at 226 degrees C. Then the styrene-b-(ethylene-co-1-butene)-b-styrene triblock copolymer (SEBS) was functionalized by BTAI via melt free radical grafting. The effect of temperature, monomer and initiator concentrations on the grafting degree and grafting efficiency was evaluated. The highest grafting degree was obtained at 200 degrees C. The grafting degree and grafting efficiency increased with the enhanced concentration of BTAI or initiator.
Dhimiter Bello - One of the best experts on this subject based on the ideXlab platform.
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an ftir investigation of Isocyanate skin absorption using in vitro guinea pig skin
Journal of Environmental Monitoring, 2006Co-Authors: Dhimiter Bello, Thomas J Smith, Susan Woskie, Robert P Streicher, Mark F Boeniger, Carrie A Redlich, Youcheng LiuAbstract:Isocyanates may cause contact dermatitis, sensitization and asthma. Dermal exposure to aliphatic and aromatic Isocyanates can occur in various exposure settings. The fate of Isocyanates on skin is an important unanswered question. Do they react and bind to the outer layer of skin or do they penetrate through the epidermis as unreacted compounds? Knowing the kinetics of these processes is important in developing dermal exposure sampling or decontamination strategies, as well as understanding potential health implications such exposure may have. In this paper the residence time of model Isocyanates on hairless guinea pig skin was investigated in vitro using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry. Model Isocyanates tested were octyl Isocyanate, polymeric hexamethylene diIsocyanate isocyanurate (pHDI), polymeric isophorone diIsocyanate isocyanurate (pIPDI) and methylenediphenyl diIsocyanate (MDI). Isocyanates in ethyl acetate (30 μL) were spiked directly on the skin to give 0.2–1.8 μmol NCO cm−2 (NCO = –NCO), and absorbance of the Isocyanate Group and other chemical Groups of the molecule were monitored over time. The ATR-FTIR findings showed that polymeric Isocyanates pHDI and pIPDI may remain on the skin as unreacted species for many hours, with only 15–20% of the total Isocyanate Group disappearing in one hour, while smaller compounds octyl Isocyanate and MDI rapidly disappear from the skin surface (80+% in 30 min). Isocyanates most likely leave the skin surface by diffusion predominantly, with minimal reaction with surface proteins. The significance of these findings and their implications for dermal exposure sampling and Isocyanate skin decontamination are discussed.
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evaluation of the niosh draft method 5525 for determination of the total reactive Isocyanate Group trig for aliphatic Isocyanates in autobody repair shops
Journal of Environmental Monitoring, 2002Co-Authors: Dhimiter Bello, Robert P Streicher, Susan WoskieAbstract:This paper evaluates the performance of the NIOSH draft method 5525 for analysis of monomeric and TRIG aliphatic Isocyanates in autobody repair shops. It was found that an optimized pH gradient enhanced noticeably the resolution and, therefore, identification of aliphatic Isocyanates. Samples proved to be very stable for at least a year when stored at −13 °C in the freezer, and no major stability problems were found for the MAP reagent. The detector response factor RSD for selected MAP ureas was 40% in the fluorescence (FLD), 3% in the UV at 254 nm (UV254), and 1% in the UV at 370 nm (UV370). The mean FLD/UV254 and UV254/UV370 detector response ratios of standards were 31.7 (RSD = 37.8) and 17.1 (RSD = 5.4), respectively. The FLD/UV254 ratio in bulks varied from 0.41 to 1.97 times the HDI monomer ratio. The mean UV254/UV370 ratio in bulks was 16.1 (range 14.1 to 19.2, N = 38). Mean (range) recovery of 92 (91.2–93.2)% was found for the N3300 (isocyanurate) spiked on 25 mm quartz fiber filters in the range 0.07 to 2.2 µg NCO ml−1. Mean (range) recovery for impingers was 100.7 (91.7–106.0)% for N3300 in the concentration range of 0.018 to 2.5 µg NCO ml−1 and 81.0 (76.1–89.1)% for IPDI in the concentration range of 0.016 to 1.87 µg NCO ml−1. Analytical method precision was 3.4% and mean bias 7.4% (range = 0–25%). The NIOSH draft method 5525 provides flexibility, enhanced sensitivity and specificity, powerful resolution, and very small compound-to-compound variability in the UV254, resulting in a more reliable identification and quantification of aliphatic Isocyanates.
Ligang Yin - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of amphiphilic polycyclooctene-graft-poly(ethylene glycol) copolymers by ring-opening metathesis polymerization
Reactive and Functional Polymers, 2010Co-Authors: Hengchong Shi, Ligang Yin, Dean Shi, Shifang Luan, Jie Zhao, Jinghua YinAbstract:Abstract In this paper, a novel monomer of 4-methyl-3-(carbamate)–carbanilic acid-4-cyclooctene ester (MCCCE) was synthesized and characterized by FTIR, NMR and ESI-MS. Polycyclooctene-graft-blocked Isocyanate copolymers were prepared by the copolymerization of MCCCE and cyclooctene via ring-opening metathesis polymerization (ROMP). Amphiphilic polycyclooctene-graft–PEG copolymers were prepared by melt mixing the polycyclooctene-graft-blocked Isocyanate copolymers with poly(ethylene glycol) (PEG) at 200 °C. The blocked Isocyanate Group on MCCCE can be dissociated to produce free Isocyanate Group, which will react with the end hydroxyl Groups on PEG molecules. The effects of monomer-to-catalyst, monomer-to-chain transfer agent ratios on molecular weight of the copolymer were detailedly studied. The water contact angle of polycyclooctene-graft–PEG copolymer is much smaller than that of polycyclooctene.
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Preparation of a blocked Isocyanate compound and its grafting onto styrene-b-(ethylene-co-1-butene)-b-styrene triblock copolymer
European Polymer Journal, 2009Co-Authors: Ligang Yin, Yanlong Liu, Jinghua YinAbstract:The epsilon-caprolactam was used to block the Isocyanate Group to enhance the storage stability of allyl (3-Isocyanate-4-tolyl) carbamate. The spectra of FTIR and NMR showed that blocked allyl (3-Isocyanate-4-tolyl) carbamate (BTAI) possesses two chemical functions, an 1-olefin double bond and a blocked Isocyanate Group. The FTIR spectrum showed BTAI could regenerate Isocyanate Group at elevated temperature. DSC and TG/DTA indicated the minimal dissociation temperature was about 135 degrees C and the maximal dissociation rate appeared at 226 degrees C. Then the styrene-b-(ethylene-co-1-butene)-b-styrene triblock copolymer (SEBS) was functionalized by BTAI via melt free radical grafting. The effect of temperature, monomer and initiator concentrations on the grafting degree and grafting efficiency was evaluated. The highest grafting degree was obtained at 200 degrees C. The grafting degree and grafting efficiency increased with the enhanced concentration of BTAI or initiator.
M J Fernandezberridi - One of the best experts on this subject based on the ideXlab platform.
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synthesis of isophorone diIsocyanate ipdi based waterborne polyurethanes comparison between zirconium and tin catalysts in the polymerization process
Progress in Organic Coatings, 2009Co-Authors: Haritz Sardon, Lourdes Irusta, M J FernandezberridiAbstract:In this work, a comparative study of the catalytic activity of tin and zirconium compounds in the polymerization of isophorone diIsocyanate (IPDI) based waterborne polyurethanes is presented. Zirconium acetyl acetonate is much less toxic than the commonly used dibutyltin diacetate but it is deactivated in the presence of acid Groups. Nevertheless, acid Groups are commonly used in the synthesis of waterborne polyurethanes and therefore these Groups have to be neutralized in advance for carrying out the synthesis using the zirconium catalyst. Moreover, FTIR and 13C NMR results have shown that in the presence of triethyl amine and tin catalyst, the secondary Isocyanate Group is more reactive than the primary Group, while using the zirconium catalyst, the two Isocyanate Groups show the same reactivity.
Kyung-do Suh - One of the best experts on this subject based on the ideXlab platform.
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blends of polybutyleneterephthalate with ethylene propylene elastomer containing Isocyanate functional Group
European Polymer Journal, 2001Co-Authors: Jungbae Jun, Donghyun Kim, Jingyu Park, Kyung-do SuhAbstract:Abstract Ethylene–propylene elastomer (EPM) grafted with an Isocyanate-containing monomer (HI) was blended with polybutyleneterephthalate (PBT), and its morphological, rheological, and mechanical properties were studied. The monomer HI was prepared by the reaction of 2-hydroxylethylmethacrylate and isophorone diIsocyanate. The HI was successfully incorporated onto EPM backbone through solution graft reaction with radical initiator. When the PBT was blended with HI-grafted EPM (EHI), the morphologies of the dispersed phase displayed differences with respect to particle size and interfacial adhesion, when compared with those of the PBT/EPM blend. The increase in complex viscosity, storage modulus and impact strength of PBT/EHI blends ensured that the compatibility between PBT and EPM was improved through functionalization of EPM with the Isocyanate moiety. These results are mainly due to in situ graft PBT–EPM copolymer that formed through the chemical reaction between the Isocyanate Group of EHI and hydroxyl or carboxyl end Groups of PBT.
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Improved compatibility of high-density polyethylene/poly(ethylene terephthalate) blend by the use of blocked Isocyanate Group
Journal of Applied Polymer Science, 2000Co-Authors: Donghyun Kim, Kang-yeol Park, Ju-young Kim, Kyung-do SuhAbstract:The blocked Isocyanate Group (BHI) was synthesized to improve the storage stability of HI (2-hydroxyethyl methacrylate combined with isophorone diIsocyanate) and characterized by Fourier transform infrared spectroscopy (FTIR). High-density polyethylene grafted with the blocked Isocyanate Group (HDPE-g-BHI) was used as a reactive compatibilizer for an immiscible high-density polyethylene/poly(ethylene terephthalate) (HDPE/PET) blend. A possible reactive compatibilization mechanism is that regenerated Isocyanate Groups of HDPE functionalized by BHI react with the hydroxyl and carboxyl Groups of PET during melt blending. The HDPE-g-BHI/PET blend showed the smaller size of a dispersed phase compared to the HDPE/PET blend, indicating improved compatibility between HDPE and PET. This increased compatibility was due to the formation of an in situ graft copolymer, which was confirmed by dynamic mechanical analysis. Differential scanning calorimetry (DSC) analysis represented that there were few changes in the crystallinity for the continuous PET phase of the HDPE-g-BHI/PET blends, compared with those of the HDPE/PET blends at the same composition. Tensile strengths and elongations at the break of the HDPE-g-BHI/PET blends were greater than those of the HDPE/PET blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1017–1024, 2000
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improved compatibility of high density polyethylene poly ethylene terephthalate blend by the use of blocked Isocyanate Group
Journal of Applied Polymer Science, 2000Co-Authors: Donghyun Kim, Kang-yeol Park, Ju-young Kim, Kyung-do SuhAbstract:The blocked Isocyanate Group (BHI) was synthesized to improve the storage stability of HI (2-hydroxyethyl methacrylate combined with isophorone diIsocyanate) and characterized by Fourier transform infrared spectroscopy (FTIR). High-density polyethylene grafted with the blocked Isocyanate Group (HDPE-g-BHI) was used as a reactive compatibilizer for an immiscible high-density polyethylene/poly(ethylene terephthalate) (HDPE/PET) blend. A possible reactive compatibilization mechanism is that regenerated Isocyanate Groups of HDPE functionalized by BHI react with the hydroxyl and carboxyl Groups of PET during melt blending. The HDPE-g-BHI/PET blend showed the smaller size of a dispersed phase compared to the HDPE/PET blend, indicating improved compatibility between HDPE and PET. This increased compatibility was due to the formation of an in situ graft copolymer, which was confirmed by dynamic mechanical analysis. Differential scanning calorimetry (DSC) analysis represented that there were few changes in the crystallinity for the continuous PET phase of the HDPE-g-BHI/PET blends, compared with those of the HDPE/PET blends at the same composition. Tensile strengths and elongations at the break of the HDPE-g-BHI/PET blends were greater than those of the HDPE/PET blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1017–1024, 2000
