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A high content of water is needed in traditional thermoplastic starch (TPS) processing to plasticize the starch and facilitate the processing, which leads to relatively low strength and modulus of the products and causes the issue of product aging partially due to the gradual water loss over time. In this work, based on the results from our previous study on lignin and cellulose nanofibril-reinforced TPS composites, a low content of citric acid (<0.5 wt%) was used to replace all the added water in the prior study (∼20 wt%). Citric acid demonstrated a much stronger viscosity-reducing effect than water and enabled composite processing at a very low acid content. The resultant nanocomposites exhibited much higher strength and modulus than those containing 20 wt% water as the processing aid. Fourier transform infrared spectrometry (FTIR) results showed strong interactions between the polar groups of starch and other ingredients. Scanning electron microscopy (SEM) photos indicated the disappearance of the two-phase "sea-island" morphology, suggesting the strong compatibilization effect of the acid. To lower the cost of the nanocomposites, we further replaced the starch and zein (an expensive biopolymer) components in the original composites with low-cost cornmeal. The new nanocomposites with cornmeal as the major ingredient exhibited similar processability and mechanical properties. With its low cost and high properties, this new type of agricultural byproduct-based nanocomposites is expected to be a promising material to replace synthetic polymers in many applications. [ABSTRACT FROM AUTHOR]

Using a one-step hydrothermal method and at different stirring speeds ( Vs), we have synthesized different types of CoFe2 O4-based magnetic nanocrystalline samples. With increasing Vs, the sample changes from a nanocomposite of CoFe2 O4/ Co0.7 Fe0.3 ( CFO/ CF) to single-phase CoFe2 O4 ( CFO). The maximum magnetization, 88.9 emu/g, and coercivity, 3010 Oe, were obtained when Vs = 0. As Vs increases, the saturation magnetization Ms decreases, because the amount of soft magnetic CF phase decreases. A clear enhancement in the remanence, Mr, was observed, with the maximum Mr/ Ms = 0.67; the coercivity Hc also exhibits a local maximum for the sample with Vs = 200 r/min. These trends can be explained well by the interplay between dipolar interaction, magnetocrystalline anisotropy, and shape anisotropy. The stirring speed also influences the impedance of the materials; the related mechanism is discussed. [ABSTRACT FROM AUTHOR]

PET/silica nanocomposite fibers of high quality were fabricated from electrospinning by choosing appropriate surface modification of inorganic fillers, solution properties, and processing conditions. The existence of an immobilized layer around silane-modified silica particles in PET fibers was verified by Fourier transform infrared spectroscopy, the results of which confirm previous thermal analysis studies. The influence of silica particles on the crystal growth during isothermal crystallization as well as the phase structure of the crystallized nanocomposite fibers were examined using differential scanning calorimetry. The PET crystallization rate increases significantly with increasing silica content, which indicates that the silica nanoparticles act as an efficient nucleating agent to facilitate PET crystallization. Using Avrami analysis, for the first time, preferred 1-D crystal growth was confirmed for geometrically confined nanocomposite fibers. Addition of silica particles makes the crystal growth more likely to occur in a 1-D manner. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the interaction of the polymer matrix and filler in electrospun nanofibers using advanced thermal analysis methods. In particular, we study the ability of silicon dioxide nanoparticles to affect the phase structure of poly(ethylene terephthalate), PET. SiO2 nanoparticles (either unmodified or modified with silane) ranging from 0 to 2.0 wt% in PET were electrospun from hexafluoro-2-propanol solutions. The morphologies of both the electrospun (ES) nanofibers and the SiO2 powders were observed by scanning and transmission electron microscopy, while the amorphous or crystalline nature of the fibers was determined by real-time wide-angle X-ray scattering. The fractions of the crystal, mobile amorphous, and rigid amorphous phases of the non-woven, nanofibrous composite mats were quantified by using heat capacity measurements. The amount of the immobilized polymer layer, the rigid amorphous fraction, was obtained from the specific reversing heat capacity for both as-spun amorphous fibers and isothermally crystallized fibers. Existence of the rigid amorphous phase in the absence of crystallinity was verified in nanocomposite fibers, and two origins for confinement of the rigid amorphous fraction are proposed. Thermal analysis of electrospun fibers, including quasi-isothermal methods, provides new insights to quantitatively characterize the polymer matrix phase structure and thermal transitions, such as devitrification of the rigid amorphous fraction. [Copyright &y& Elsevier]

Morphology-controlled porous α-Fe 2 O 3 /SnO 2 nanorods with uniform surface heterostructures have been fabricated by a facile surface modification of rod-like α-Fe 2 O 3 nanomaterials by changing the adding amount of Sn composition, displaying the excellent selectivity and sensitivity of gas-sensing to acetone. The introduction of SnO 2 nanoparticles had the great effects on tuning the crystal size, crystallinity, and surface status, as well as the structural stability and phase distribution of α-Fe 2 O 3 /SnO 2 nanorods. Compared to pure α-Fe 2 O 3 , α-Fe 2 O 3 /SnO 2 heterostructures can exhibit the optimal gas-sensing behavior with the sensitivity up to 53.1 and the response and recovery times decreasing to 9 and 2.5 s at the operating temperature of 260 °C, respectively. The enhanced gas-sensing performance can be mainly attributed to the combination of uniform porous structures, narrow size-distribution, large specific surface area, and heterostructures of the interface between α-Fe 2 O 3 and SnO 2 . [ABSTRACT FROM AUTHOR]