Phase transitions in biodegradable films based on blends of gelatin and poly (vinyl alcohol)

Sobral, Paulo José do Amaral; Carvalho, Rosemary Aparecida de; Moraes, Izabel Cristina Freitas; Bittante, Ana Mônica Quinta Barbosa; Monterrey-Quintero, Ednelí Soraya

doi:10.1590/s0101-20612011000200015

Cited by 17 publications

(21 citation statements)

References 34 publications

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“…Alguns termogramas representativos dos filmes de colágeno, gelatina e fécula de mandioca são apresentados na Figura 29. As curvas DSC da primeira varredura nos filmes de proteínas proporcionaram termogramas típicos de materiais parcialmente cristalinos (SOBRAL et al, 2011). Com o aumento da temperatura foi observado uma Tg, que oscilou entre -77 e -70 °C (Tabela 7), sendo associada à fase rica em glicerol (SOBRAL et al, 2001).…”

Section: Calorimetria Diferencial De Varreduraunclassified

“…Este comportamento tem sido extensamente observado na literatura, sendo atribuído à separação do biopolímero e o glicerol (JORGE, 2012;MAKISHI, 2016;SOBRAL et al, 2001;VANNIN et al, 2005). Na sequência, foi observado um pico endotérmico típico em materiais parcialmente cristalinos (SOBRAL et al, 2011), em temperaturas entre 57 e 76 °C (Tabela 8), sendo associado à fusão dos cristais presentes no colágeno e na gelatina (MAKISHI, 2016;PRESTES, 2012;SOBRAL et al, 2001;VANNIN et al, 2005). Na segunda varredura de temperaturas nos filmes de proteínas foram observados termogramas típicos de materiais amorfos, com duas Tg: a primeira Tg aconteceu na mesma faixa de temperaturas descrita previamente, sendo associada à fração rica em glicerol (Tabela 7) e, a segunda Tg foi observada para uma faixa de temperaturas entre 21 e 34 °C, sendo associada à fração rica em biopolímero (Tabela 7).…”

Section: Calorimetria Diferencial De Varreduraunclassified

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Propriedades físicas de filmes à base de biopolímeros reforçados com laponita

Valencia¹

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The environmental problems caused by packaging based on non-biodegradable synthetic materials have lead to a significant increase in studies about biopolymer films. However, these films have limited physicochemical properties due mainly to its sensitivity to ambient relative humidity. Among the alternatives studied to improve the physicochemical properties of these materials is the use of nanoparticles, especially the montmorillonite, which has problems of dispersion in water. Another nanoparticle no so much studied in films based on biopolymers is laponite, which is a synthetic nanoparticle. Thus, this these aims to development and characterize films based on biopolymers (collagen, gelatin and cassava starch), with a nanoparticle (laponite). The effects of biopolymer and laponite concentrations were studied, as well as, the film production method (casting and spreading), besides the quality of laponite dispersion and its relationship with the physicochemical properties of the films were investigated, with special interest on the surface properties. The films were produced by the dehydration of filmogenic-forming solutions (FFS), with 2, 4 or 8 g of biopolymer/100 g FFS; 25 or 30 g glycerol/100g of biopolymer; and 0, 1.5, 3, 4.5 and 6 g of laponite/100g of biopolymer. The laponite was dispersed in water using ultraturrax, at 20,000 rpm, for 30 minutes. The laponite particles in water had sizes smaller than 50 nm. There was not effect of biopolymer concentration and film production method (casting or spreading) on the surface and physicochemical properties studied in the nanocomposite films. X-ray analysis and Fourier transform infrared spectroscopy revealed that laponite platelets were exfoliated and/or intercalated in the films, and that there were no formed chemical bonds between laponite platelets and the biopolymers studied. The presence of laponite increased the surface irregularity of the films, especially in those produced with collagen and cassava starch. Other properties in the nanocomposite films, such density, moisture content, color, opacity, thermal properties, mechanical properties, water solubility, water contact angle, sorption isotherms and water vapor permeability were not altered by the presence of laponite.

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Section: Calorimetria Diferencial De Varreduraunclassified

Propriedades físicas de filmes à base de biopolímeros reforçados com laponita

Valencia¹

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“…Os termogramas da primeira e segunda varredura dos filmes de gelatina sem adição de glicerol e plastificados com 25% de glicerol apresentaram comportamento típico de materiais parcialmente cristalinos (SOBRAL et al, 2011) Figura 19. Curvas de calorimetria diferencial de varredura de filmes de gelatina com diferentes concentrações de glicerol, após condicionamento a 44 %(UR).…”

Section: Propriedades Térmicasunclassified

Propriedades dielétricas de suco de laranja, goiabada em pasta e filmes de gelatina

Flaker¹

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pela orientação, dedicação, paciência, compreensão e apoio constante durante cada etapa deste trabalho. Ao Prof. Alberto Sereno (in memoriam) pelos valiosos aportes. Ao Prof. Yrjö Roos pela orientação e confiança durante o estágio sanduiche na Universidade de Cork. Aos amigos do LTA, pelo carinho e apoio durante todos estes anos. À minha família e amigos pelo apoio incondicional. À CAPES pela concessão da bolsa de doutorado. Ao FoRC e à FAPESP (projeto CEPID 2013/07914-8) pelo apoio financeiro para realizar atividades relacionadas ao projeto. A todas as pessoas que contribuíram de alguma forma à realização deste trabalho, muito obrigado. EPIGRAFE "A ciência é composta de erros, mas são erros que é útil cometer, porque levam pouco a pouco à verdade."

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“…Sua obtenção pode ser a partir de tecido cutâneo e ósseo de animais (como por exemplo, bois, bezerro, porco) pela hidrólise parcial ácida ou alcalina da macromolécula de colágeno (sendo denominadas comercialmente tipo A e B, respectivamente) (SOBRAL et al, 2011). As propriedades químicas e físicas das gelatinas comerciais podem variar em virtude das diversas fontes de colágeno e dos diferentes métodos para sua obtenção (ROMAN;SGARBIERI, 2007).…”

Section: Filmes De Gelatinaunclassified

Instrumentação para a caracterização dielétrica de filmes biodegradáveis

Cremasco¹

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The dielectric characteristics of a material can be used as a non-destructive technique to evaluate and monitor the quality as well as the understanding of the structure-property of a material, through its dielectric properties as a function of frequency, temperature, chemical composition of the material, among others. In the literature there are few studies and data of dielectric characterization of films based on biopolymers. In this context, the objective of this research was the development and construction of an alternative instrumentation equipment on the market, such as network and impedance analyzers, which could be used for the dielectric characterization of biodegradable films based on gelatin. The method of parallel plates was used to determine the real part of permittivity known as relative permittivity or dielectric constant (ε'). The circuit used for the instrumentation was an astable oscillator operation based on operational amplifier (741) switched by the load of a parallel plate capacitor whose dielectric was a sample of the biodegradable film. From the values of the oscillation frequency and geometry of the capacitor, it was possible to calculate the capacitance of each sample and thus obtaining values of the relative permittivity of the film, using well established basic relationships. Gelatin films were produced by casting technique being used as plasticizer glycerol (G), sorbitol (S) and mixtures thereof, in proportion (G:S) 30:70, 50:50 and 70:30. The films were characterized for moisture and crystallinity. The relative permittivity (ε') of the films, determined at room temperature, was evaluated as a function of frequency (5-50 kHz), storage time, moisture content and type of plasticizer. The designed and constructed instrumentation was able to accurately measure the relative permittivity of the samples, being that this property decreased with increasing frequency for all films. Keeping constant frequency, there was no variation in ε' for the gelatin films, independent of the plasticizer over one month of storage at 24 ± 3 ⁰C. The moisture effect was observed at frequencies lower than 25 kHz, how bigger the moisture content the higher the relative permittivity. The effect of the plasticizer type in relative permittivity of the films were observed at low frequency (5 kHz) and plasticized films with sorbitol have higher ε' values. The plasticized films with higher moisture content exhibit lower crystallinity, hence larger molecular mobility and consequently higher the relative permittivity.

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Phase transitions in biodegradable films based on blends of gelatin and poly (vinyl alcohol)

Cited by 17 publications

References 34 publications

Propriedades físicas de filmes à base de biopolímeros reforçados com laponita

Propriedades físicas de filmes à base de biopolímeros reforçados com laponita

Propriedades dielétricas de suco de laranja, goiabada em pasta e filmes de gelatina

Instrumentação para a caracterização dielétrica de filmes biodegradáveis

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