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Composites made of linear low-density polyethylene (LLDPE) and β-cyclodextrin/d-limonene inclusion complex (CD-lim) were prepared by melt extrusion to develop a novel food packaging material. Scanning electron microscopy evidenced a fairly good dispersion of the filler within the polymeric matrix. Infrared spectroscopy coupled with thermogravimetric analysis confirmed the presence of CD-lim in the composites, proving that the applied technology of including the essential oil within β-CD cages allows for preventing a sizable loss of d-limonene despite a high temperature and shear applied upon extrusion processing. Moreover, the influence of the filler on the thermal properties of PE was assessed. It was found that the cyclodextrin-based inclusion complex significantly fastens the crystallization path of the polyethylene matrix with an improved crystallization rate of the PE/CD-lim composites compared to the neat polymer. [ABSTRACT FROM AUTHOR]

This work presents selected properties of polypropylene-based (PP) composites modified with an organic filler, namely walnut shells (NUT). Two series of composites were prepared via a twin-screw extrusion process, followed by injection molding. The first series, named PP/NUT, contained 10, 20 and 40 wt% of walnut shell powder, while the second, abbreviated PP/NUT/MAPP, apart from nut filler included polypropylene-graft-maleic anhydride (MAPP), which was intended to promote adhesion between the polymer and filler. The following measuring techniques were applied: differential scanning calorimetry, thermogravimetry, dynamic-mechanical thermal analysis, and scanning electron microscopy. The measurements showed the filler to have a significant influence on the properties of the PP/NUT composites in comparison with unmodified polypropylene. It was also shown that the addition of polypropylene-graft-maleic anhydride to the formulation enhanced interfacial bonding between the polymeric matrix and filler. Moreover, the introduction of organic filler to the polymeric matrix increased its stiffness without altering the crystallization kinetics of polypropylene. [ABSTRACT FROM AUTHOR]

Wood-polymer composites based on high-density polyethylene and two types of pine-wood filler were investigated. It is shown that the addition of long wood fibres to common polyethylene leads to a substantial increase in stiffness, i.e. from 504 MPa for PE-HD up to 1526 MPa for PE-HD with 60% wood fibres. Moreover, morphological investigations revealed that superficial wood particles were sufficiently embedded in the base polymer ensuring protection against higher moisture uptake rates. [ABSTRACT FROM AUTHOR]

Bio-based composites made of poly(L-lactic acid) (PLLA) and β-cyclodextrin/d-limonene inclusion complex (CD-Lim) were prepared by melt extrusion. Encapsulation of volatile d-limonene molecules within β-cyclodextrin cages was proven to be a successful strategy to prevent evaporation during high-temperature processing. However, small amounts of limonene were released upon processing, resulting in the plasticization of the polymeric matrix. Morphological analysis revealed good dispersion of the filler, which acted as a nucleating agent, favoring the growth of PLLA crystals. The composites′ lowered glass transition temperature upon the addition of CD-Lim was also proved by thermomechanical analysis (DMA). Moreover, DMA revealed constant stiffness of modified materials at room temperature, which is crucial in PLLA-based formulations. [ABSTRACT FROM AUTHOR]

BaTiO 3 /polymer composites, which combine the high dielectric constant of ceramics with the high dielectric strength of polymers, are used in modern microelectronics as capacitors, piezoelectric transducers and optoelectronic elements. The aim of the work was to determine the effect of barium titanate (BT) nanoparticles on physical properties of polyester resin (PR). The introduction of nanoparticles into a cross-linked polyester resin induces changes in its molecular structure and dynamics as a result of the particle-polymer interface. Molecular dynamics of polyester resin filled with barium titanate nanoparticles with BT content of 0.1% wt. and 1% wt. was studied. The internal motion of cured polyester resin and new PR/BT composites was investigated by different 1H NMR techniques. The temperature dependences of the spin-lattice relaxation times T 1 in the laboratory frame and the frequency dispersions of the spin-lattice off-resonance relaxation times T 1 ρ off in the rotating frame were determined. Also, the first derivative of the absorption 1H NMR signal was recorded and the second moment of the signal was determined as a function of temperature. Differential Scanning Calorimetry was employed to study the thermal properties of the samples. The results showed that BT nanoparticles influenced the molecular dynamics and thermal properties of polyester resin. The addition of BT nanoparticles leads to a decrease in the correlation times and in the activation energy of internal motion in composites, compared with those for pure polyester resin. What is more, the glass transition temperature T g and the thermal decomposition temperature T D of polymer composites shift to lower values. Image 1 • The internal motion of new composites was investigated by different NMR techniques. • The influence of nanoparticles on molecular dynamics of polyester resin was probed. • The filler reduce the degree of crosslinking. [ABSTRACT FROM AUTHOR]

Bio-based composites made of poly(l-lactic acid) (PLLA) and pine wood were prepared by melt extrusion. The composites were compatibilized by impregnation of wood with γ-aminopropyltriethoxysilane (APE). Comparison with non-compatibilized formulation revealed that APE is an efficient compatibilizer for PLLA/wood composites. Pine wood particles dispersed within PLLA act as nucleating agents able to start the growth of PLLA crystals, resulting in a faster crystallization rate and increased crystal fraction. Moreover, the composites have a slightly lower thermal stability compared to PLLA, proportional to filler content, due to the lower thermal stability of wood. Molecular dynamics was investigated using the solid-state 1H NMR technique, which revealed restrictions in the mobility of polymer chains upon the addition of wood, as well as enhanced interfacial adhesion between the filler and matrix in the composites compatibilized with APE. The enhanced interfacial adhesion in silane-treated composites was also proved by scanning electron microscopy and resulted in slightly improved deformability and impact resistance of the composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • nHAp/PLDLLA composites with wt.% ratio: 10/90 and 20/80 were prepared by an-extrusion process. • Structural properties of the filler and polymeric blends were characterized in detail. • Mechanical results and density values were reported as close to human bone. • Contact angle analysis showed a favored growth of tissue on the biocomposite containing 10 wt% nHAp. • The PLDLLA-based composite can be an excellent candidate for bone reconstruction implants. A novel, bone-reconstruction dedicated polymeric-nanohydroxyapatite material has been prepared for 3D-printed implant. The composites of poly(L-lactide- co -D,L-lactide) (PLDLLA) and nanosized hydroxyapatite were prepared by a co-rotating twin-screw extrusion. Structural properties of the filler and polymeric blends were characterized by XRD (X-ray Powder Diffraction), SEM (Scanning Electron Microscopy), and EDS mapping (energy dispersive spectroscopy), FT-IR (Fourier-transformed infrared spectroscopy), and NMR (Nuclear Magnetic Resonance) technics. Molar masses of the composites at various preparation steps were also investigated. The structural studies and thermogravimetric analysis proved a successful preparation of the nanohydroxyapatite and its nanocomposites. Mechanical results in conjunction with density values, reported as close to human bone, evidenced usability of this novel material for internal bone fixation implant. Contact angle analysis showed favored growth of tissue on the biocomposite containing 10 wt% of the filler. The PLDLLA-based composite can be an excellent candidate for bone reconstruction implants due to their superior mechanical properties, bioactivity, and complete resorbability. [ABSTRACT FROM AUTHOR]