1,721,035 research outputs found
Poly(lactic acid) (PLA) based blends and composites: new perspectives for biodegradable and renewable materials
No full textEffect of free radical reactions onto Structure and properties of poly(lactic acid) (PLA) based blends
No full textThe blending of PLA with poly(butylene-adipate-co-terephthalate) (PBAT) is a promising strategy to
achieve a toughened multiphase material. The blends ductility could be further improved through
reactive compatibilization, i.e. inducing the formation of comb PLA-PBAT copolymers during the melt
blending. In the present work a non-selective strategy was adopted which consisted in the use of
a peroxide, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane. The phase morphology development and the
final properties (torque, fluidity in the melt, tensile behaviour, thermal and dynamicalemechanical
features) of the blends were studied as a function of the peroxide concentration. The elongation at break
was improved up to a maximum value thanks to this approach and a corresponding minimum was
observed in the value of the dispersed phase diameter. A structural characterization of the macromolecules
formed during the reactive process was attempted by using size exclusion chromatography of the
blends and comparison with the pure polymers obtained by processing in the presence of the peroxid
Polymerization Kinetics and Characterization of Dual Cured Polyurethane‐Acrylate Nanocomposites for Laminates
No full textFour different types of montmorillonites have been dispersed by sonication at 50 degrees C into a propoxylated aromatic epoxy diacrylate oligomer to achieve interlayered or exfoliated nanocomposites. A thermally-induced cross-linking reaction, forming a polyurethane network in the presence of 7 wt.-% of a montmorillonite, has been promoted by addition of an allophanate modified polyisocyanurate based on hexamethylene diisocyanate. The kinetic behavior of the network formation has been studied at 25, 40 and 60 degrees C by following the disappearance of the isocyanate vibrational band found at 2 270 cm(-1). A tight crosslinked polyurethane acrylate network has been achieved by a subsequent dual UV curing promoted by a photoinitiator mixture (0.6 wt,-%) added to the reactive mixture because of further reactions occur to the acrylate double bonds. The photopolymerization kinetic has been investigated on the different thermally treated polyurethane nanocomposite networks by Real Time FTIR spectroscopy monitoring the changes of the IR band at 810 cm(-1) assigned to the acrylate double bond vibrations. The influence of the different montmorillonite clays on the final nanocomposite morphology has been investigated by using XRD and SEM. Finally, the use of these mixtures as internal layer between two modified surface PET films has been also studied for the laminate production. The based-PET laminate films have been characterized by determining the bending resistance and optical properties as a function of different nanofillers
Biodegradable and Compostable PLA-based formulations to replace plastic disposable commodities
No full textNew renewable and environmentally friendly materials through molecular modification and blending of biorelated polymers
No full textPolymer melt intercalation and in situ polymerization of lactide in innovative organophilic montmorillonites
No full textThermal degradation of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephtalate) (PBAT) as a consequence of melt processing: effects on pure materials and their blends
No full textPoly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are biodegradable aliphatic
polyesters, which being semicrystalline and thermoplastic can be processed by conventional methods.
Their blends give interesting materials for industrial packaging applications, due to their increased
ductility as PBAT content increases. However, like many aliphatic polyesters, the PLA matrix degrades
upon melt processing thus affecting the thermo-mechanical features of the blended material. In this
work, we studied the effect of processing at high temperature on the molecular weight distribution,
morphology, and thermo-mechanical properties of both homopolymers, as well as the PLA/PBAT 75/25
blend. Notably, different processing conditions were adopted in terms of temperature (range 150–200 C)
and other relevant processing parameters (moisture removal and nitrogen atmosphere). Analysis of PLA/
PBAT blends indicated that intermolecular chain reactions took place under strong degradative conditions
of PLA, yielding PLA/PBAT mixed chains (copolymers). Increasing amounts of copolymers resulted
in improved phase dispersion and increased ductility, as SEM and mechanical tests indicated. Conversely,
reduced PLA degradation with less copolymer formation, afforded higher modulus materials, owing to
poorer dispersion of the soft phase (PBAT) into the PLA matrix
Polymers from Fossil and Renewable Resources. Scientific and Technological Comparison of Plastic Properties
No full textThe book describes the development and commercialization of materials with viscoelastic properties, placing particular emphasis on the scientific and technological differences between plastics and bioplastics. The authors explain how to handle each of the two types of materials and determine the comparative environmental impact of the material life-cycle. The practical values of the overlapping aspects of the two types of materials from technical properties to eco-compatibility are also discusse
Amorphous/crystal and polymer/filler interphases in biocomposites from poly(butylene succinate)
No full textPoly(butylene succinate)-hemp composites (PBS-hemp), with hemp content
in the range 0-40 wt.\%, were prepared in the melt and characterized.
This paper focuses on the detailed analysis of the thermal behaviour of
the PBS-hemp composites, investigated by differential scanning
calorimetry (DSC), to enlighten the polymer/fibre interphase features.
The occurrence of specific intermolecular interactions between PBS and
hemp was assessed from specific heat capacity data. Different degrees of
mobility of the PBS amorphous segments were found at the
amorphous/crystal interphases. A broadening of the bulk glass transition
was observed, and attributed to the presence of polymer segments
slightly constrained. Moreover, a rigid amorphous fraction that
devitrifies at temperatures higher than the bulk glass transition,
partly before the melting region and partly simultaneously with the
fusion, was observed and quantified, and attributed to the presence of
major constraints probably occurring in geometrically restricted areas.
(C) 2012 Elsevier B.V. All rights reserved
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