Caracterização de polietilenos lineares de baixa densidade I.: determinação do teor de ramificação por métodos espectroscópicos

Quental, Antonio C.; Hanamoto, Lilian S.; Felisberti, Maria I.

doi:10.1590/s0104-14282005000400012

Polímeros

2005

DOI: 10.1590/s0104-14282005000400012

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Caracterização de polietilenos lineares de baixa densidade I.: determinação do teor de ramificação por métodos espectroscópicos

Antonio C. Quental

Lilian S. Hanamoto

Maria I. Felisberti

Abstract: Resumo: Os polietilenos lineares de baixa densidade (LLDPE) apresentam propriedades variando amplamente em função da concentração e do tipo de comonômero utilizado na copolimerização, além do tipo de catalisador. Neste trabalho diversos tipos de LLDPE obtidos com diferentes tipos de comonômeros e catalisadores foram caracterizados estruturalmente por RMN-13 C e FTIR. Os resultados obtidos por meio destas duas técnicas foram discutidos e comparados.Palavras-chave: Polietileno, caracterização, RMN 13 C, FTIR, co… Show more

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Cited by 4 publications

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Tailoring LLDPE properties with modified palygorskite fillers: A comprehensive study

da Silva,

Quinteiro,

Melo

et al. 2024

Polymer Engineering & Sci

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Linear low‐density polyethylene (LLDPE) is a polyolefin known for its superior low‐temperature heat seal ability, low‐temperature tolerance, and bag‐tear resistance which are important features for the polymeric packaging sector. In this work, to improve the mechanical properties and expand the range of applications of LLDPE, the microfibrillar clay mineral palygorskite (PAL) was added. However, the use of PAL as a reinforcing agent for polymers depends on its purification process to extract accessory minerals such as calcite, dolomite, and quartz. In addition to this purification process, two surface modifications were used on the purified PAL (PALp) to improve interactions with LLDPE: silanization with aminosilane (PALs) and organophilization by incorporating an organic compound (PALo). The PAL were characterized according to their morphological properties using transmission electron microscopy (TEM), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT‐IR). The films of LLDPE/PAL, with varying levels (1, 3, and 5 wt%) and types of PAL (raw PAL, PALp, PALs, and PALo), were prepared by an extrusion process, and films were prepared by compression molding, without preferred orientation. The films were characterized by rheological analyses, tensile tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and water vapor permeability. Incorporating modified PAL was significant in enhancing the mechanical properties of the nanocomposites. LLDPE/PALs with the addition of 3 wt% PALs showed a 14% increase in elastic modulus (281.08 ± 8.25 MPa) compared to the nanocomposite with 3 wt% of raw PAL (243.43 ± 15.01 MPa).Highlights The PAL is a clay mineral with a fibrous morphology and has a low cost. The technique to purify PAL is a quick, simple, and inexpensive technique. Comparison between of two technique surface modification of PAL. The effectiveness of modifications of PAL was confirmed in LLDPE films. The surface modification with silanization was more effective.

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Tailoring LLDPE properties with modified palygorskite fillers: A comprehensive study

da Silva,

Quinteiro,

Melo

et al. 2024

Polymer Engineering & Sci

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show abstract

Mechanical, Thermal and Morphological Characterization of High-Density Polyethylene and Vermiculate Composites

Oliveira¹,

Visconte²,

Vendramini³

2009

International Journal of Polymeric Materials

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Caracterização de polietilenos lineares de baixa densidade II: fracionamento por cristalização isotérmica a partir do estado fundido

2005

Self Cite

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Linear low-density polyethylenes (LLDPE) are a class of polyethylenes with linear chains containing only short chain branches due to the insertion of α-olefin units during the copolymerization with ethene. The α-olefins commonly used are 1-butene, 1-hexene and 1-octene. Depending on the α-olefin and the catalyst used for the polymerization, LLDPE presents different microstructures which determine the thermal and mechanical properties. One simple and efficient method to evaluate the microstructure of LLDPE is the fractionation by Multiple-Step Isothermal Crystallization from Melting State conducted by DSC. This method is based on several steps of isothermal crystallization of the polymer on decreasing the temperature from the melt. This process favors the separation of the crystalline material into groups having different lamellae thickness depending on the amount and distribution of the α-olefin units in the macromolecular chains and on the molar mass. The melting endotherm of a fractionated sample is made up of the same number of peaks as the isothermal crystallization steps, which inform the relative comonomers distributions between different LLDPE chains. In this work, this methodology was applied to determine the relative comonomers distribution of different LLDPE. The isothermal temperature, temperature range and the time influence the efficiency of the fractionation and these parameters must be chosen according to the LLDPE microstructure.

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Caracterização de polietilenos lineares de baixa densidade I.: determinação do teor de ramificação por métodos espectroscópicos

Cited by 4 publications

References 8 publications

Tailoring LLDPE properties with modified palygorskite fillers: A comprehensive study

Tailoring LLDPE properties with modified palygorskite fillers: A comprehensive study

Mechanical, Thermal and Morphological Characterization of High-Density Polyethylene and Vermiculate Composites

Caracterização de polietilenos lineares de baixa densidade II: fracionamento por cristalização isotérmica a partir do estado fundido

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