Search results for "Copolyester"

Effect of Graphene Nanoplatelets on the Physical and Antimicrobial Properties of Biopolymer-Based Nanocomposites

2016

In this work, biopolymer-based nanocomposites with antimicrobial properties were prepared via melt-compounding. In particular, graphene nanoplatelets (GnPs) as fillers and an antibiotic, i.e., ciprofloxacin (CFX), as biocide were incorporated in a commercial biodegradable polymer blend of poly(lactic acid) (PLA) and a copolyester (BioFlex®). The prepared materials were characterized by scanning electron microscopy (SEM), and rheological and mechanical measurements. Moreover, the effect of GnPs on the antimicrobial properties and release kinetics of CFX was evaluated. The results indicated that the incorporation of GnPs increased the stiffness of the biopolymeric matrix and allowed for the t…

Effect of polarity and elongational flow on the morphology and properties of a new nanobiocomposite

2015

Nanocomposites are a new class of biodegradable polymer materials with an ultrafine phase dispersion of the order of a few nanometers in a biodegradable polymer matrix that shows very interesting properties often very different from those of conventional filled polymers. In this work the effect of the polarity of the organomodified montmorillonite and of the elongational flow on the morphology and the rheological and mechanical properties of a new nanobiocomposite having as a matrix a biodegradable copolyester based bland has been investigated. The morphology of the nanocomposite with the more polar organomodified clay shows a more exfoliated morphology due to the major compatibility with t…

Thermomechanical Properties of Radiation-Modified Polyethylene/Ethylene-Propylene-Diene Copolymer/Liquid-Crystalline Copolyester Blends

1999

Radiation-modified blends of high-density polyethylene (PE) with ethylene-propylene-diene copolymer (EPDM; 10-65 wt.%) and thermotropic liquid-crystalline polymer (LCP; 10 wt.%) were investigated. The LCP was a liquid-crystalline copolyester of 40% poly(ethylene terephthalate) with 60% 4-hydroxybenzoic acid. The constituents were blended using a circular extruder, the specimens were prepared by compression molding and irradiated by 60Co γ-radiation up to 200 kGy. Mechanical, thermal, and morphological properties in wide temperature range were investigated for the irradiated and non-irradiated specimens. The effects of irradiation on the thermomechanical behaviour of the PE matrix are discus…

Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 4. Polyester und copolyester der milchsäure und glykolsäure

1978

Polyesters and copolyesters of 2-hydroxyacetic acid (glycolic acid) and 2-hydroxypropionic acid (lactic acid) were investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation of these polyesters and copolyesters at 10−6 mbar yields cyclic oligomers which are further degraded by an electron impact induced mechanism by elimination of formaldehyde or acetaldehyde and CO2 to give characteristic series of linear ions. In the pyrolysis mass spectrum of a copolyester (mole ratio of monomeric units ≈1:1) intact sequences up to 8 monomeric units can be observed.

Properties of radiation-modified blends of polyethylene with elastomers and liquid crystalline copolyester

2001

The results are given on the effect of γ-irradiation on properties of blends of high and low-density polyethylene (HDPE, LDPE) with elastomers -ethylene/propylene/diene rubber (EPDM) and chlorinated polyethylene (CPE), and thermotropic liquid crystalline polymer (LCP). The morphological, thermal, mechanical properties (including thermosetting properties) and adhesion properties of blended composites were investigated. A special attention was paid to the applicability of the blends as thermosetting materials (TSM). The LCP used was a copolyester of poly(ethylene terephthalate) with p-(hydroxybenzoic acid) in the ratio 40: 60. It was found that addition of LCP essentially influenced the therm…

On the use of PET-LCP copolymers as compatibilizers for PET/LCP blends

1996

Copolyesters of poly[ethylene terephthalate) (PET) with a liquid crystalline polymer (LCP), SBH 1:1:2, have been synthesized by the polycondensation, carried out in the melt at temperatures up to 300 degrees C of sebacic acid (S), 4,4'-dihydroxybiphenyl (B), and 4-hydroxybenzoic acid (H) in the presence of PET. The PET-SBH copolyesters have been characterized by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, etc., and the relationships between properties and preparation conditions are discussed. The copolyesters show a biphasic nature, which is more evident for the products synthesized with a thermal profile comprising relatively lower temperatures (220-…

Liquid Crystalline Copolyester Made from Recycled Polyethylene Terephthalate and p-Acetoxybenzoic Acid: Synthesis, Characterization and Blending with…

2013

Effects of filler type and mixing method on the physical properties of a reinforced semirigid liquid crystal polymer

1996

Semirigid liquid crystalline polymers (LCPs) show some advantages with respect to rigid LCP: in particular lower processing temperatures, better compatibility with flexible thermoplastics, but also some disadvantages. Thermal resistance of rigid LCPs is much better and the maximum working temperature is, in general, very high. The thermomechanical properties can be improved by adding inorganic fillers. In this work processing, mechanical and thermomechanical properties of a filled semirigid liquid crystal copolyester are reported. Several inorganic fillers have been used in order to put in evidence the influence of shape and dimensions of the particles on the properties of the filled materi…

Effect of the Components Molar Mass and of the Mixing Conditions on the Compatibilization of PE/LCP Blends by PE-g-LCP Copolymers

1999

The rheology, morphology, and mechanical properties of blends of high-density polyethylene (HDPE) with a semiflexible liquid crystalline copolyester (SBH) were studied in order to assess the compatibilizing ability of added PE-g-SBH copolymers, and its dependence on the molar mass of the PE matrix, and on the technique used for blend preparation. The PE-g-SBH copolymers were synthesized as described in previous articles, either by the polycondensation of the SBH monomers in the presence of a functionalized PE sample containing free carboxyl groups, or by reactive blending of the latter polymer with preformed SBH. Two samples of HDPE having different molar masses, and two samples of SBH with…

Thermomechanical properties of radiation-modified blends of polyethylene with liquid crystalline copolyester

1999

The results of investigation of gamma irradiated blends of high-density polyethylene (PE) with thermotropic polymer liquid crystal (PLC) are presented. The PLC used was a copolyester of 40% poly(ethylene terephthalate) with 60% p-(hydroxy-benzoic acid). The PLC content in the blends was 0, 5, and 10 wt%. The constituents were blended with the use of a single screw extruder. The specimens were prepared by compression molding. The irradiation of the samples was performed by a Co 60 γ-radiation source in inert atmosphere (argon) up to absorbed relatively low doses (up to 200 kGy: 1 Mrad = 10 kGy). The morphological, thermal, and mechanical properties were investigated for irradiated and unirra…