Página 1 dos resultados de 131 itens digitais encontrados em 0.003 segundos

Polymer toughening using residue of recycled windshields: PVB film as impact modifier

VALERA, Ticiane Sanches; DEMARQUETTE, Nicole Raymonde
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
409.55727%
In this work, poly(vinyl butyral) (PVB) film originated from the mechanical separation of windshields was tested as all impact modifier of Polyamide-6 (PA-6). The changes undergone by PVB film during the recycling process and the blend manufacturing were evaluated by thermal analyses, infrared spectroscopy and loss oil ignition. Blends of PA-6/original PVB film and PA-6/recovered PVB film were obtained in concentrations ranging from 90/10 to 60/40. The mechanical properties of the blends were investigated and explained in light of the blends morphologies, which in turns were correlated to the changes undergone by the PVB film during the recycling process. The original film presented a plasticizer content of 33 wt.%, which decreased to as low as 20 wt.%, after the recycling and blend preparation processes. The PA-6/PVB film blends presented lower values of tensile strength and Young`s modulus than Polyamide-6, but all blends presented a dramatic increase in their toughness, with a special feature for the 40 wt.%(, blend, which resulted in a super toughened material (impact strength exceeding 500 J/m). Similar results were obtained with recovered PVB film and super tough blends were also obtained. The use of recovered PVB resulted in a smaller improvement of the impact strength due to the loss of plasticizer undergone during the recycling process. The morphological observations showed that if the interparticle distance is smaller than around 0.2 mu m (critical value)...

Biobased films prepared from NaOH/thiourea aqueous solution of chitosan and linter cellulose

MORGADO, D. L.; FROLLINI, E.; CASTELLAN, A.; ROSA, D. S.; COMA, V.
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
373.03875%
In the present study, films based on linter cellulose and chitosan were prepared using an aqueous solution of sodium hydroxide (NaOH)/thiourea as the solvent system. The dissolution process of cellulose and chitosan in NaOH/thiourea aqueous solution was followed by the partial chain depolymerization of both biopolymers, which facilitates their solubilization. Biobased films with different chitosan/cellulose ratios were then elaborated by a casting method and subsequent solvent evaporation. They were characterized by X-ray analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermal analysis, and tests related to tensile strength and biodegradation properties. The SEM images of the biofilms with 50/50 and 60/40 ratio of chitosan/cellulose showed surfaces more wrinkled than the others. The AFM images indicated that higher the content of chitosan in the biobased composite film, higher is the average roughness value. It was inferred through thermal analysis that the thermal stability was affected by the presence of chitosan in the films; the initial temperature of decomposition was shifted to lower levels in the presence of chitosan. Results from the tests for tensile strength indicated that the blending of cellulose and chitosan improved the mechanical properties of the films and that an increase in chitosan content led to production of films with higher tensile strength and percentage of elongation. The degradation study in a simulated soil showed that the higher the crystallinity...

Combination of guided mode and photometric optical metrology methods for precise determination of refractive index dispersion: application to polymer blend and ceramic thin films for gas sensors

Wood, Thomas; Le Rouzo, Judikaël; Flory, François; Coudray, Paul; Mastelaro, Valmor Roberto; Pelissari, Pedro; Zilio, Sérgio Carlos
Fonte: International Society for Optical Engineering - SPIE; Bellingham Publicador: International Society for Optical Engineering - SPIE; Bellingham
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
383.9422%
Two optical techniques, m-lines and spectroscopic ellipsometry, are compared for their suitability for obtaining the wavelength and the temperature dispersion of the refractive index of thin-film layers used in gas detector devices. Two types of materials that are often integrated into gas sensors are studied: a polymer organic-inorganic blend deposited by spin coating typically used in near-infrared waveguides and the ceramic semiconductor SrTi1-xFexO3 (strontium titanate) doped with iron at concentrations x = 0.075 and 0.1 deposited by electron beam deposition. The refractive index dispersion obtained by m-lines and ellipsometry is compared, and the differences between the measured parameters for the two materials are discussed. The chromatic dispersion will be represented by a three-term Cauchy law. An intuitive method for verifying the measured indices using an integrating sphere and reflexion coefficient modeling techniques are also demonstrated. Thermo-optic coefficients in the order of -1 × 10-4/K for both materials are reported, and very low chromatic dispersions are also measured, thanks to the high sensitivity of the m-lines technique. The uniaxial anisotropic properties of the polymerblend films are measured and discussed in the case of the semiconductor films.; ANR; CAPES/COFECUB

Dependence of the electrical conductivity and elastomeric properties on sample preparation of blends of polyaniline and natural rubber

Camillo, E. C.; Constantino, CJL; Teruya, M. Y.; Alves, Neri; Mattoso, LHC; Job, A. E.
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 1498-1503
ENG
Relevância na Pesquisa
398.31734%
Blend films (free-standing) containing 20% in volume of polyaniline (PANI) in 80% of natural rubber (NR) were fabricated by casting in three different ways: (1) adding PANI-EB (emeraldine base) dissolved in N-methyl-2-pyrrolidone (NMP) to the latex (NRL), (2) adding PANI-EB dissolved in in-cresol to NR dissolved in xylol (NRD), (3) overlaying the surface of a pure NR cast film with a PANI layer grown by in situ polymerization (NRO). All the films were immersed into HCl solution to achieve the primary doping (protonation) of PANI before the characterization. The main goal here was to investigate the elastomeric and electrical conductivity properties for each blend, which may be applied as pressure and deformation sensors in the future. The characterization was carried out by optical microscopy, dc conductivity, vibrational spectroscopy (infrared absorption and Raman scattering), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile stress-strain curves. The results suggest that the NRL blend is the most suitable in terms of mechanical and electrical properties required for applications in pressure and deformation sensors: a gain of conductivity without losing the elastomeric property of the rubber. (c) 2005 Wiley Periodicals...

Biodegradation of the Films of PP, PHBV and Its Blend in Soil

Goncalves, S. P. C.; Martins-Franchetti, S. M.; Chinaglia, D. L.
Fonte: Springer/plenum Publishers Publicador: Springer/plenum Publishers
Tipo: Artigo de Revista Científica Formato: 280-285
ENG
Relevância na Pesquisa
393.9036%
Films of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly(propylene) (PP), PP/PHBV (4:1), blends were prepared by melt-pressing and investigated with respect to their microbial degradation in soil after 120 days. Biodegradation of the films was evaluated by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction. The biodegradation and/or bioerosion of the PP/PHBV blend was attributed to microbiological attack, with major changes occurring at the interphases of the homopolymers. The PHBV film was more strongly biodegraded in soil, decomposing completely in 30 days, while PP film presented changes in amorphous and interface phase, which affected the morphology.

Action of soil microorganisms on PCL and PHBV blend and films

Goncalves, S. P. C.; Martins-Franchetti, S. M.
Fonte: Springer/plenum Publishers Publicador: Springer/plenum Publishers
Tipo: Artigo de Revista Científica Formato: 714-719
ENG
Relevância na Pesquisa
398.31734%
Poly(hydroxybutyrate-co-valerate) (PHBV) and poly(epsilon-caprolactone) (PCL) PCL/PHBV (4:1) blend films were prepared by melt-pressing. The biodegradation of the films in response to burial in soil for 30 days was investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The PHBV film was the most susceptible to microbial attack, since it was rapidly biodegraded via surface erosion in 15 days and completely degraded in 30 days. The PCL film also degraded but more slowly than PHBV. The degradation of the PCL/PHBV blend occurred in the PHBV phase, inducing changes in the PCL phases (interphase) and resulting in an increase of its crystalline fraction.

Biotransformation of poly (epsilon-caprolactone) and poly (vinyl chloride) blend

Campos, Adriana de; Franchetti, Sandra Mara Martins; Agnelli, José Augusto Marcondes
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: 111-113
ENG
Relevância na Pesquisa
388.3559%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Poli épsilon-caprolactona é um importante polímero biodegradável e miscível com o PVC, um polímero sintético industrial, termo susceptível e não biodegradável. A blenda PVC/PCL é importante em propriedades mecânicas e biodegradabilidade. Neste trabalho, há indicações que há interação dos microrganismos com a superfície polimérica e esta causa mudanças estruturais na blenda PVC/PCL.; Poly (caprolactone) is a famous biodegradable polymer and miscible with PVC, a commercial synthetic polymer, thermal susceptible and non-biodegradable. This blend is important concerning its mechanical properties and biodegradability. In this work, we testified the biomodification of blend films of PVC/PCL by UV-Vis. spectroscopy. The results show us that there is an interaction between the PVC/PCL film and the microrganisms.

Preparation and characterization of castor oil-based polyurethane/poly(o- methoxyaniline) blend film

Alves, William F.; Kanda, Darcy H. F.; Malmonge, Luiz F.; Malmonge, José A.; Mattoso, Luiz H. C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 706-709
ENG
Relevância na Pesquisa
493.9036%
Blends made up of castor oil-based polyurethane (PU) and poly(o-methoxyaniline) (POMA) were obtained in the form of films by casting and characterized by FTIR, UV-Vis-NIR spectroscopy, and electrical conductivity measurements. Doping was carried out by immersing the films in 1.0M HCl aqueous solution. Chemical bonds between NCO group of PU and NH group of POMA were observed by means of FTIR spectra. The UV-Vis-NIR spectra indicated that the presence of the PU in the blend does not affect doping and formation of the POMA phase. The electrical conductivity research was in the range of 10-3 S/cm. © 2007 Wiley Periodicals, Inc.

Estudo da biodegradação dos filmes de poli (e-caprolactona), da blenda poli (e-caprolactona)/amido e do composito poli (e-caprolactona)/amido/po de fibra de coco por fungos e bacterias; Study of poli (e-caprolactone), poli (e-caprolactone)/starch blend and poli (e-caprolactone)/starch/coconut fiber biodegradated by fungi and bacteria

Livia Cordi
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/02/2008 PT
Relevância na Pesquisa
403.46664%
Imensurável é a quantidade de resíduos plásticos descartados no meio ambiente e o crescente desequilíbrio do mesmo. Esta situação leva ao desenvolvimento de novas formulações plásticas que sejam resistentes e funcionais enquanto em uso, mas que após o período de interesse sejam degradados no menor período de tempo possível. Com o intuito de minimizarmos as quantidades de polímeros descartados no meio ambiente, dentro de uma perspectiva de desenvolvimento sustentável e diminuindo a poluição ambiental, estudamos a aplicação de fungos e bactérias isolados de solo para reduzir o tempo de degradação de polímeros considerados biodegradáveis. Para isto, foi preparada e caracterizada uma blenda composta por Poli (e- caprolactona) e Amido de milho adipatado e também um compósito de Poli (e- caprolactona), Amido de milho adipatado e pó de fibra de coco, visando assim obter um material com alta taxa de biodegradação. A caracterização e o acompanhamento da biodegradação do filme de PCL, da blenda PCL/amido e do compósito PCL/amido/fibra de coco foi feita por Análise Visual, Perda de Massa, Espectroscopia no Infra-Vermelho Próximo (NIR), Análise Termogravimétrica (TGA), Microscopia Eletrônica de Varredura (MEV)...

Biorefinery valorization of autohydrolysis wheat straw hemicellulose to be applied in a polymer-blend film

Ruiz, Héctor A.; Cerqueira, M. A.; Silva, Hélder D.; Rodríguez-Jasso, Rosa María; Vicente, A. A.; Teixeira, J. A.
Fonte: Elsevier; Elsevier Publicador: Elsevier; Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2013 ENG
Relevância na Pesquisa
386.73133%
The aims of this study were the extraction of hemicellulose from wheat straw (WS) and its utilization in the reinforcement of a κ-carrageenan/locust bean gum (κ-car/LBG) polymeric blend films (PBFs). WS hemicellulose extraction was performed under autohydrolysis process and hemicellulose extracted (HE) under optimum condition was used in PBFs. PBFs were prepared varying different proportions of HE into the κ-car/LBG film-forming solutions. Barrier properties (water vapor permeability, WVP), mechanical properties (tensile-strength, TS, and elongation-at-break, EB), moisture content, opacity and thermal properties of the resulting PBFs were determined and related with the incorporation of HE. The 2-3-2 proportion (in the high ratio) of PBF (κ-car/LBG/HE) causes a slight decrease of WVP and an increase of the TS, thus resulting in an improvement of the physical properties of PBFs. HE showed to be a promising material in order to reinforce κ-car/LBG PBF and can be an alternative in the application of hemicellulose according to biorefinery concept.

Modification of hydrophobic polypeptide-based film by blending with hydrophilic poly(acrylic acid)

Zhu,Guoquan; Wang,Fagang; Gao,Qiaochun; Liu,Yuying
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
506.52516%
In this study, a series of poly(γ-benzyl L-glutamate)/poly(acrylic acid) (PBLG/PAA) polymer blend films were prepared by casting the polymer blend solution in dimethylsulfoxide (DMSO). The structure and morphology of the polymer blend film were investigated by Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). Thermal, mechanical, and chemical properties of PBLG/PAA polymer blend films were studied by Differential Scanning Calorimetry (DSC), Thermogravimetric (TG) Analysis, Tensile Tests, and measurements of Surface Contact Angles. The results revealed that the introduction of PAA could exert great effects on the structure and properties of the polypeptide films.

Study on properties of poly(vinyl alcohol)/polyacrylonitrile blend film

Zhu,Guoquan; Wang,Fagang; Xu,Kejing; Gao,Qiaochun; Liu,Yuying
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
603.46664%
In this work, a series of poly(vinyl alcohol) (PVA)/polyacrylonitrile (PAN) blend films with different PAN mole contents were prepared by casting the polymer blend solution in dimethylsulfoxide (DMSO). Surface morphologies of PVA/PAN blend films were analyzed by Scanning Electronic Microscopy (SEM) and Atomic Force Microscopy (AFM). Thermal, mechanical, and chemical properties of PVA/PAN blend films were investigated by Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Tensile Tests, and Surface Contact Angle Tests. The results showed that the introduction of PAN could exert marked effects on the properties of PVA films.

Physicochemical properties of poly(lactic acid-co-glycolic acid) film modified via blending with poly(butyl acrylate-co-methyl methacrylate)

Zhu,Guoquan; Wang,Fagang; Gao,Qiaochun; Liu,Yuying
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
501.30727%
A series of poly(lactic acid-co-glycolic acid) (PLGA)/poly(butyl acrylate-co-methyl methacrylate) (P(BA-co-MMA)) blend films with different P(BA-co-MMA) mole contents were prepared by casting the polymer blend solution in chloroform. Surface morphologies of the PLGAP(BA-co-MMA) blend films were studied by scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of PLGAP(BA-co-MMA) blend films were investigated by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), tensile tests, and surface contact angle tests. The introduction of P(BA-co-MMA) could modify the properties of PLGA films.

Biotransformation of poly (epsilon-caprolactone) and poly (vinyl chloride) blend

Campos,Adriana de; Franchetti,Sandra Mara Martins; Agnelli,José Augusto Marcondes
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2003 EN
Relevância na Pesquisa
388.3559%
Poly (caprolactone) is a famous biodegradable polymer and miscible with PVC, a commercial synthetic polymer, thermal susceptible and non-biodegradable. This blend is important concerning its mechanical properties and biodegradability. In this work, we testified the biomodification of blend films of PVC/PCL by UV-Vis. spectroscopy. The results show us that there is an interaction between the PVC/PCL film and the microrganisms.

Influence of an Acrylic Polymer Blend on the Physical Stability of Film-Coated Theophylline Pellets

Kucera, Shawn; Shah, Navnit H.; Malick, A. Waseem; Infeld, Martin H.; McGinity, James W.
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 01/07/2009 EN
Relevância na Pesquisa
311.89559%
The purpose of this study was to investigate the physical stability of a coating system consisting of a blend of two sustained release acrylic polymers and its influence on the drug release rate of theophylline from coated pellets. The properties of both free films and theophylline pellets coated with the polymer blend were investigated, and the miscibility was determined via differential scanning calorimetry. Eudragit® RS 30 D was plasticized by the addition of Eudragit® NE 30 D, and the predicted glass transition temperature (Tg) of the blend was similar to the experimental values. Sprayed films composed of a blend of Eudragit® NE 30 D/Eudragit® RS 30 D (1:1) showed a water vapor permeability six times greater than films containing only Eudragit® NE 30 D. The presence of quaternary ammonium functional groups from the RS 30 D polymer increased the swellability of the films. The films prepared from the blend exhibited stable permeability values when stored for 1 month at both 25°C and 40°C, while the films which were composed of only Eudragit® NE 30 D showed a statistically significant decrease in this parameter when stored under the same conditions. Eudragit® NE 30 D/Eudragit® RS 30 D (1:1)-sprayed films decreased in elongation from 180% to 40% after storage at 40°C for 1 month...

Silk Nanospheres and Microspheres from Silk/PVA Blend Films for Drug Delivery

Wang, Xiaoqin; Yucel, Tuna; Lu, Qiang; Hu, Xiao; Kaplan, David L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
301.30727%
Silk fibroin protein-based micro- and nanospheres provide new options for drug delivery due to their biocompatibility, biodegradability and their tunable drug loading and release properties. In the present study, we report a new aqueous-based preparation method for silk spheres with controllable sphere size and shape. The preparation was based on phase separation between silk fibroin and polyvinyl alcohol (PVA) at a weight ratio of 1/1 and 1/4. Water-insoluble silk spheres were easily obtained from the blend in a three step process: (1) air-drying the blend solution into a film, (2) film dissolution in water and (3) removal of residual PVA by subsequent centrifugation. In both cases, the spheres had approximately 30% beta-sheet content and less than 5% residual PVA. Spindle-shaped silk particles, as opposed to the spherical particles formed above, were obtained by stretching the blend films before dissolving in water. Compared to the 1/1 ratio sample, the silk spheres prepared from the 1/4 ratio sample showed a more homogeneous size distribution ranging from 300 nm up to 20 μm. Further studies showed that sphere size and polydispersity could be controlled either by changing the concentration of silk and PVA or by applying ultrasonication on the blend solution. Drug loading was achieved by mixing model drugs in the original silk solution. The distribution and loading efficiency of the drug molecules in silk spheres depended on their hydrophobicity and charge...

Development of a Chemiresistor Sensor Based on Polymers-Dye Blend for Detection of Ethanol Vapor

dos Reis, Marcos A. L.; Thomazi, Fabiano; Nero, Jordan Del; Roman, Lucimara S.
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 29/03/2010 EN
Relevância na Pesquisa
403.53523%
The conductive blend of the poly (3,4-ethylene dioxythiophene) and polystyrene sulfonated acid (PEDOT-PSS) polymers were doped with Methyl Red (MR) dye in the acid form and were used as the basis for a chemiresistor sensor for detection of ethanol vapor. This Au | Polymers-dye blend | Au device was manufactured by chemical vapor deposition and spin-coating, the first for deposition of the metal electrodes onto a glass substrate, and the second for preparation of the organic thin film forming ∼1.0 mm2 of active area. The results obtained are the following: (i) electrical resistance dependence with atmospheres containing ethanol vapor carried by nitrogen gas and humidity; (ii) sensitivity at 1.15 for limit detection of 26.25 ppm analyte and an operating temperature of 25 °C; and (iii) the sensing process is quickly reversible and shows very a low power consumption of 20 μW. The thin film morphology of ∼200 nm thickness was analyzed by Atomic Force Microscopy (AFM), where it was observed to have a peculiarly granulometric surface favorable to adsorption. This work indicates that PEDOT-PSS doped with MR dye to compose blend film shows good performance like resistive sensor.

Eudragit L/HPMCAS Blend Enteric-Coated Lansoprazole Pellets: Enhanced Drug Stability and Oral Bioavailability

Fang, Yu; Wang, Guozheng; Zhang, Rong; Liu, Zhihua; Liu, Zhenghua; Wu, Xiaohui; Cao, Deying
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 05/03/2014 EN
Relevância na Pesquisa
301.30727%
The objectives of the present work were to use blends of Eudragit L and hydroxypropyl methylcellulose acetate succinate (HPMCAS) as enteric film coatings for lansoprazole (LSP) pellets. The enteric-coated pellets were prepared with a fluid-bed coater. The influence of the blend ratio, type of plasticizer, plasticizer level, coating level, and curing conditions on gastric stability in vitro drug release and drug stability was evaluated. Furthermore, the bioavailability of the blend-coated pellets in beagle dogs was also performed. The blend-coated pellets exhibited significant improvement of gastric stability and drug stability compared to the pure polymer-coated pellets. Moreover, the AUC values of blend-coated pellets were greater than that of the pure polymer-coated pellets. It was concluded that the using blends of Eudragit L and HPMCAS as enteric film coatings for LSP pellets improved the drug stability and oral bioavailability.

Characterization of quinoa proteinechitosan blend edible films

Tapia, Cristián; Yazdani-Pedram Zobeiri, Mehrdad; Díaz Dosque, Mario; Villamán, María C.; Abugoch James, Lilian Elizabeth
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo de revista
EN
Relevância na Pesquisa
414.0708%
Quinoa protein/chitosan films were obtained by solution casting of blends of quinoa protein extract (PE) and chitosan (CH). Films from a PE/CH blend were characterized by FTIR, X-ray diffraction, thermal analysis, and SEM. The tensile mechanical, barrier, and sorption properties of the films were also evaluated. The blend of PE with CH yielded mechanically resistant films without the use of a plasticizer. The film had large elongation at break, and its water barrier properties showed that they were more hydrophilic than CH film. The thickness and water-vapor permeability of PE/CH (v/v) 1/1 blend film increased significantly compared to pure CH films. CH films are translucent in appearance and yellowish in blend with PE. By blending anionic PE with cationic CH an interaction between biopolymers was established with different physicochemical properties from those of pure CH. Drying and sorption properties show significant differences between PE/CH blend film and CH film. The structural properties determined by XRD, FTIR and TGA showed a clear interaction between quinoa proteins and CH, forming a new material with enhanced mechanical properties.

Blends of UV-cross-linkable model compound and polyimide; Effect of UV exposure on viscosity and mechanical properties

Zope, Indraneel
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
376.7699%
The ultimate goal of this project is to synthesize a novel UV-cross-linkable non-linear optical (NLO) pendant polyimide. The following work is dedicated to the synthesis and exposure optimization of the UV cross-linkable component. Knowing that highly stable NLO properties can be achieved through cross-linked polymer matrices, where polymer chain immobilization leads to unidirectional orientation of NLO-phores in poled polymer resulting in maximized operational lifetime and the complete cross-linking cannot be achieved even after a long irradiation time for a photo-cross-linkable polymer, a chalcone-based UV curable Model Compound was synthesized and exposed to UV light. Optimization was carried out with respect to four factors: (1) UV light wavelength, (2) Solvent for exposure, (3) Solution concentration and (4) Optimum exposure time. For (1)-(3), UV light of 300nm, lower concentrations of solutions and tetrahydrofuran as a solvent were established using LC Mass Spectroscopy, UV-Vis Spectroscopy, FTIR and NMR characterization techniques. For (4), we determined the optimum curing time for maximum polymer chain immobilization, as reflected by Model Compound solution viscosity and mechanical properties of Model Compound-Polyimide blends (1:7 by weight). Tensile and Dynamic Mechanical Analysis (DMA) analysis of blend films agreed with viscosity results that exposure beyond 45 minutes yielded little additional cross-linking in our UV exposure apparatus.