Caracterização viscosimétrica de nanocompósitos híbridos PS/POSS Viscometric characterization of PS/POSS hybrid nanocomposites

Nanocompósitos híbridos de poliestireno (PS) e poliedros oligoméricos silsesquioxanos (POSS) com diferentes composições e graus de hibridização foram obtidos por processamento reativo no estado fundido utilizando-se peróxido de dicumila (DCP) como iniciador, na presença ou não de estireno como agente de transferência de radical. Os materiais foram caracterizados viscosimetricamente por cromatografia de permeação em gel (GPC) usando detecção tripla por espalhamento de luz, viscosimetria e índice de refração. As amostras PS/POSS processadas com estireno apresentaram maiores valores de massa molar ponderal média (Mw) e menores valores de polidispersão (Mw/Mn), devido ao maior grau de conversão da reação de hibridização do PS-POSS (28-40%) e do menor grau de degradação (cisão) das cadeias do PS, quando comparadas com amostras PS/POSS processadas sem estireno nas quais o grau de conversão ficou em torno de 24-28%. Para os sistemas PS e PS/POSS em solução com THF, os parâmetros da equação de Mark-Houwink-Sakurada (MHS), &#945; &#8773; 0,7 e log K &#8773; -3,5 a -3,9 e os valores dos parâmetros de interação polímero-solvente, &#967;ij &#8773; 0,49, não apresentaram diferenças significativas com relação aos tamanhos moleculares. Por outro lado, essas diferenças de tamanhos moleculares foram caracterizadas por uma função cumulativa da fração mássica de cadeias em função da distância média quadrática entre pontas de cadeia (< r² >0½).<br>Polystyrene (PS) and polyhedral oligomeric silsesquioxanes (POSS) hybrid nanocomposites with different compositions were obtained by reactive melt processing using dicumyl peroxide (DCP) as initiator in the presence or absence of styrene as radical transfer agent. The materials were characterized by viscosimetry by means of gel permeation chromatography (GPC) using triple-detector: light scattering, viscometer and refractive index. PS/POSS samples processed with styrene showed higher weight average molecular weights (Mw) and lower polydispersity indexes (Mw/Mn), as a result of higher PS-POSS conversion (28-40%) and lower PS degradation, as compared to the PS/POSS samples processed without styrene in which the degree of conversion was lower (24-28%). For the PS/POSS solutions in THF, the parameters of the Mark-Houwink-Sakurada equation, &#945; &#8773; 0.7 and log K &#8773; -3.5 to -3.9, and the values of polymer-solvent interaction parameter, &#967;ij &#8773; 0.49, were not changed with respect to changes in molecular size. On the other hand, these changes were characterized by a cumulative function of the mass fraction of chains as a function of the root mean square end to end distance (< r² >0½)

ATLANTIC BIRD TRAITS: a data set of bird morphological traits from the Atlantic forests of South America

Scientists have long been trying to understand why the Neotropical region holds the highest diversity of birds on Earth. Recently, there has been increased interest in morphological variation between and within species, and in how climate, topography, and anthropogenic pressures may explain and affect phenotypic variation. Because morphological data are not always available for many species at the local or regional scale, we are limited in our understanding of intra- and interspecies spatial morphological variation. Here, we present the ATLANTIC BIRD TRAITS, a data set that includes measurements of up to 44 morphological traits in 67,197 bird records from 2,790 populations distributed throughout the Atlantic forests of South America. This data set comprises information, compiled over two centuries (1820–2018), for 711 bird species, which represent 80% of all known bird diversity in the Atlantic Forest. Among the most commonly reported traits are sex (n = 65,717), age (n = 63,852), body mass (n = 58,768), flight molt presence (n = 44,941), molt presence (n = 44,847), body molt presence (n = 44,606), tail length (n = 43,005), reproductive stage (n = 42,588), bill length (n = 37,409), body length (n = 28,394), right wing length (n = 21,950), tarsus length (n = 20,342), and wing length (n = 18,071). The most frequently recorded species are Chiroxiphia caudata (n = 1,837), Turdus albicollis (n = 1,658), Trichothraupis melanops (n = 1,468), Turdus leucomelas (n = 1,436), and Basileuterus culicivorus (n = 1,384). The species recorded in the greatest number of sampling localities are Basileuterus culicivorus (n = 243), Trichothraupis melanops (n = 242), Chiroxiphia caudata (n = 210), Platyrinchus mystaceus (n = 208), and Turdus rufiventris (n = 191). ATLANTIC BIRD TRAITS (ABT) is the most comprehensive data set on measurements of bird morphological traits found in a biodiversity hotspot; it provides data for basic and applied research at multiple scales, from individual to community, and from the local to the macroecological perspectives. No copyright or proprietary restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications or teaching and educational activities. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ

ATLANTIC BIRD TRAITS

Scientists have long been trying to understand why the Neotropical region holds the highest diversity of birds on Earth. Recently, there has been increased interest in morphological variation between and within species, and in how climate, topography, and anthropogenic pressures may explain and affect phenotypic variation. Because morphological data are not always available for many species at the local or regional scale, we are limited in our understanding of intra- and interspecies spatial morphological variation. Here, we present the ATLANTIC BIRD TRAITS, a data set that includes measurements of up to 44 morphological traits in 67,197 bird records from 2,790 populations distributed throughout the Atlantic forests of South America. This data set comprises information, compiled over two centuries (1820–2018), for 711 bird species, which represent 80% of all known bird diversity in the Atlantic Forest. Among the most commonly reported traits are sex (n = 65,717), age (n = 63,852), body mass (n = 58,768), flight molt presence (n = 44,941), molt presence (n = 44,847), body molt presence (n = 44,606), tail length (n = 43,005), reproductive stage (n = 42,588), bill length (n = 37,409), body length (n = 28,394), right wing length (n = 21,950), tarsus length (n = 20,342), and wing length (n = 18,071). The most frequently recorded species are Chiroxiphia caudata (n = 1,837), Turdus albicollis (n = 1,658), Trichothraupis melanops (n = 1,468), Turdus leucomelas (n = 1,436), and Basileuterus culicivorus (n = 1,384). The species recorded in the greatest number of sampling localities are Basileuterus culicivorus (n = 243), Trichothraupis melanops (n = 242), Chiroxiphia caudata (n = 210), Platyrinchus mystaceus (n = 208), and Turdus rufiventris (n = 191). ATLANTIC BIRD TRAITS (ABT) is the most comprehensive data set on measurements of bird morphological traits found in a biodiversity hotspot; it provides data for basic and applied research at multiple scales, from individual to community, and from the local to the macroecological perspectives. No copyright or proprietary restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications or teaching and educational activities. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ