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71.
The mechanical properties of isotactic polypropylene (iPP) and propylene-ethylene block copolymer (Co-PP) with carbon black (CB) were added as a filler. By mixing appropriate amounts of the two components through melt-blending in a twin-screw extruder, the blended pellets were prepared to a series of test specimens by injection molding. A scanning electron microscopic study was performed of the morphologies of the impact fractured surfaces. The blending of CB in Co-PP not only improves the impact strength, but also improves the flexural modulus and tensile strength; however, the heat distortion temperature (HDT) of the Co-PP/CB blends decreased with greater filler content. Furthermore, the filler of CB improves the tensile yield strength only at low filler content in iPP/CB blends, and the heat distortion temperature (HDT) and flexural modulus of the iPP/CB blends increased with greater filler content. The impact behavior is not good for the iPP/CB blends. Overall, Co-PP/CB has better interaction of molecules than iPP/CB. © 1996 John Wiley & Sons, Inc. 相似文献
72.
73.
Chin-Hao Li Tai-Ying Chen Chien-Chen Wu Shih-Hsuan Cheng Min-Yu Chang Wei-Hong Cheng Shih-Hau Chiu Chien-Chi Chen Ying-Chieh Tsai Deng-Jye Yang Jaw-Jou Kang Po-Lin Liao 《International journal of molecular sciences》2023,24(1)
Lacticaseibacillus paracasei strain PS23 (PS23) exhibits some probiotic properties. In this study, a genomic analysis of PS23 revealed no genes related to virulence or antibiotic resistance. Moreover, ornithine decarboxylase activity was not detected in vitro. In addition, PS23 was sensitive to the tested antibiotics. Genotoxicity tests for PS23 including the Ames test and chromosomal aberrations in vitro using Chinese hamster ovary cells and micronuclei in immature erythrocytes of ICR mice were all negative. Moreover, following a 28-day study involving repeated oral dose toxicity tests (40, 400, and 4000 mg/kg equal 1.28 × 1010, 1.28 × 1011, and 1.28 × 1012 CFU/kg body weight, respectively) using an ICR mouse model, no adverse effects were observed from any doses. In addition, supplementation with live or heat-killed PS23 ameliorates DSS-induced colonic inflammation in mice. Our findings suggest that PS23 is safe and has anti-inflammatory effects and may therefore have therapeutic implications. 相似文献
74.
Blending is an effective method for improving polymer properties. However, the problem of phase separation often occurs due to incompatibility of homopolymers, which deteriorates the physical properties of polyblends. In this study, isotactic polypropylene was blended with low-density polyethylene. Crosslinking agent and copolymers of propylene and ethylene (either random copolymer or block copolymer) were added to improve the interfacial adhesion of PP/LDPE blends. The tensile strength, heat deflection temperature, and impact strength of these modified PP/PE blends were investigated. The microstructures of polyblends have been studied to interpret the mechanical behavior through dynamic viscoelasticity, wide-angle X-ray diffraction, differential scanning calorimetry, picnometry, and scanning electron microscopy. The properties of crosslinked PP/PE blends were determined by the content of crosslinking agent and processing method. For the material blended by roll, a 2% concentration of peroxide corresponded to a maximum tensile strength and minimum impact strength. However, the mechanical strength of those products blended by extrusion monotonously decreased with increasing peroxide content because of serious degradation. The interfacial adhesion of PP/PE blends could be enhanced by adding random or block copolymer of propylene and ethylene, and the impact strength as well as ductility were greatly improved. Experimental data showed that the impact strength of PP/LDPE/random copolymer ternary blend could reach as high as 33.3 kg · cm/cm; however, its rigidity and tensile strength were inferior to those of PP/LDPE/block copolymer blend. 相似文献
75.
In this research, poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles less than 100 nm were synthesized first and applied as the solid stabilizer for producing PEDOT-polystyrene (PEDOT-PSt) composite latex by Pickering emulsion polymerization. The results showed that most PEDOT nanoparticles adhered to the PSt core particles having the size from 100 to 250 nm. By casting the latex, the obtained PEDOT-PSt film had a surface resistance of 4–5 kΩ/□, almost the same as the pure PEDOT film, though its PEDOT content was only 6.2 wt%. Those PEDOT nanoparticles in the outer layer could contact with one another, forming a continuous network as the conductive passageway. Furthermore, soft latex particles of poly(styrene-co-butyl acrylate), P(St-BA), were synthesized and mixed with the conducting rigid PEDOT-PSt latex for improving the toughness and transparency of the casting film. A critical point at about 2 wt% of PEDOT content in the PEDOT-PSt/P(St-BA) film was observed in the surface resistance measurement. 相似文献
76.
Lin CF Zhang M Liu SW Chiu TL Lee JH 《International journal of molecular sciences》2011,12(1):476-505
This paper introduces the fundamental physical characteristics of organic photovoltaic (OPV) devices. Photoelectric conversion efficiency is crucial to the evaluation of quality in OPV devices, and enhancing efficiency has been spurring on researchers to seek alternatives to this problem. In this paper, we focus on organic photovoltaic (OPV) devices and review several approaches to enhance the energy conversion efficiency of small molecular heterojunction OPV devices based on an optimal metal-phthalocyanine/fullerene (C(60)) planar heterojunction thin film structure. For the sake of discussion, these mechanisms have been divided into electrical and optical sections: (1) Electrical: Modification on electrodes or active regions to benefit carrier injection, charge transport and exciton dissociation; (2) Optical: Optional architectures or infilling to promote photon confinement and enhance absorption. 相似文献
77.
With an atomic-force microscope and a grazing-incidence small-angle X-ray scattering we studied ex situ the evolution of hierarchical structures in isothermally annealed ultrathin films of asymmetric polystyrene-block-poly(methyl methacrylate) P(S-b-MMA) that dewetted on polar substrates via a mechanism involving nucleation and growth. Film instability causes the surface to acquire an undulating thickness through incommensurability, producing not only the relief structures on a micrometer scale but also mesophase-separated domains on a nanometer scale. The dewetted morphologies strongly influence the ordering behavior of the nanoscale domains. The noncylindrical nanostructures become stable at the curved edges of the relief microstructures in the destabilized P(S-b-MMA) films, for which a preferential wetting of the PS block with the free surface is prohibited. Additionally, the shape of relief structures as result of film instability correlates with the formation of mesophase-separated nanodomains. At early stages of film instability, the formation of parallel-oriented PMMA cylindrical nanodomains increases the deformation energy and it further persists to force the shape of relief structures between irregular holes to have a facet-wedge shape. However, those relief structures are expected to be not at equilibrium. At high temperatures, the relief structures between irregular holes progressively developed to form hemispherical-cap drops accompanied by a transformation of cylindrical into noncylindrical nanodomains at curved surfaces. 相似文献
78.
A facile approach of forming stable polymeric complexes by the two-stage phase transition of the graft copolymer comprising poly(acrylic acid) (PAAc) as the backbone and poly(N-isopropylacrylamide) (PNIPAAm) and monomethoxy poly(ethylene glycol) (mPEG) as the grafts in water was illustrated. Rather loose and hydrated polymeric aggregates with a characteristic hydrophobic multicore structure, achieved by the first-stage thermally induced phase transition of PNIPAAm grafts, underwent the core structure rearrangement (including multicore fragmentation and fusion) upon the second-stage dehydration of mPEG grafts at 90 °C. This was followed by hydrogen-bond pairings of mPEG and PNIPAAm chain segments with unionized AAc residues acting as an effective protective shell against potential hydration of the hydrophobic inner cores during the annealing process. The polymer complexes thus obtained show surprisingly enhanced hydrophobicity of inner cores at 25 °C in water and excellent stability of the morphological structure in response to the temperature disturbance. 相似文献
79.
The physical properties of nylon 6/poly(acrylonitrile-butadiene-styrene) terpolymer (ABS) blends using a maleated polybutadiene
(denoted PB-g-MA) as compatibilizer were investigated. The morphology results reveal that ABS domain sizes decrease with an
increasing compatibilizer content, suggesting the good interaction between the nylon 6 matrix and the ABS dispersed phase.
Cooling conditions and compatibilizer contents strongly affect the crystalline structure of nylon 6, as determined from X-ray
diffraction and non-isothermal crystallization thermal analyses. The coexistence of α- and predominantly γ-form crystals for
the 10 phr compatibilized blends was observed. Isothermal crystallization kinetics suggests that the introduced compatibilizer
impeded the growth rate of the crystals, especially for the higher compatibilizer content. The compatibilizer was beneficial
in enhancing the thermal stability of the blends. 相似文献
80.
Leilane Costa de Conto Marco Antonio Lefevre Gragnani Diogo Maus Hiria Cristina Ifanger Ambiel Ming Chih Chiu Renato Grimaldi Lireny Aparecida Guaraldo Gonçalves 《Journal of the American Oil Chemists' Society》2011,88(11):1709-1714
The aim of this paper was to study the physical–chemical composition of the watermelon seed oil extracted by a mechanical process using an expeller and by a chemical process using hexane as the solvent. The watermelon seed oil had a high concentration of unsaturated fatty acids. The two primary sterols were stigmasterol and β-sitosterol, which corresponded to approximately 47 and 30% of the total phytosterols. The oil had a low tocopherol content (65.19 mg/kg for S and 73.19 mg/kg for E). Comparing the two extraction methods, extraction by expeller produced an oil of superior quality with respect to oxidative stability, carotenoids and Lovibond color. No significant differences were found between the two extraction methods with respect to the minor components of the oil considered as functional, such as phytosterols. 相似文献