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Supercritical CO2 (scCO2) extrusion foamed high-melt-strength (HMS) polypropylene (PP) often suffers from low cell density, large cell sizes, and poor cell structure uniformity due to the poor nucleation rates of CO2 in the PP. To remedy this, various inorganic fillers have been used as heterogeneous nucleation agents. Although their efficient nucleation effects have been demonstrated, the preparation of these fillers causes some adverse effects on the environment/human health or involves relatively expensive processes or non-eco-friendly chemicals. In this work, biomass-based lignin is studied as a sustainable, lightweight, and cost-effective nucleating agent. It is found that scCO2 could assist in situ dispersion of lignin in the PP in the foaming process, leading to significantly increased cell density, smaller cells, and improved cell uniformity. The Expansion Ratio is also simultaneously improved due to reduced diffusive gas loss. The PP/lignin foams with low lignin loadings exhibit higher compression moduli and plateau strengths than the PP foams with the same densities owing to the improved cell uniformity and probably also the reinforcing effect of the small lignin particles in cell walls. Moreover, the energy absorption capability of the PP/lignin foam with 1 wt% lignin could match the PP foam with similar compression plateau strengths; even the density of the former is 28% lower than the latter. Therefore, this work provides a promising approach to a cleaner and more sustainable production of HMS PP foams. [ABSTRACT FROM AUTHOR]

Studies on computer-assisted language instruction have shown that using technology can provide students with a sense of empowerment and help them develop effective learning strategies and communicative abilities. However, little research has been done on the effects of using technology in teaching Chinese as a foreign language. This paper explores the potential impact of a theory-driven Course Web Site (CWS) on students' academic performance. The test of two-factor ANOVA and the test of the significance of difference between two independent proportions were applied in analyzing the data. The findings indicated that the mean examination score of the students exposed to the CWS was significantly higher, F(2, 130) = 2.65, p less than 0.05, than that of those who were not. The use of the CWS interacted insignificantly with the instructor variations. The probability of success for the students exposed to the CWS increased significantly, t = 2.25, = 0.05, in terms of the proportion of students scoring B or above on the end-of-semester examination.

Studies variation in reading speed between languages of different orthographies, focusing on modern Chinese with logographic characters and English with an alphabetic writing system. Finds that the Chinese readers are faster than the English readers by about two minutes on the same reading material; the difference is significant even with reading comprehension being held constant. (SC)

We report, the preparation of nanocomposites having polyimide (PI) as matrix and graphene oxide (GO) as filler, analyses of matrix-filler interactions, and enhancements in thermomechanical properties of PI/GO as compared with pristine Pl. The matrix-filler interactions were analyzed by [.sup.1]H NMR, X-ray photoelectron spectroscopy, and density functional theory calculations. The data suggested stronger matrix-filler interactions in PI/GO as compared with PUG composites. The stronger matrix-filler interactions and homogeneous dispersion of fillers lead to a significant enhancement in mechanical properties in PI/GO nanocomposites. Thus, with just 1 wt% GO content, the modulus of PI/GO composite increased by ~106% as compared with pristine Pl. Finally, thermal expansion coefficients of the nanocomposites are also investigated. A plausible hypothesis has been proposed in the text to explain the observed matrix-filler interactions and the subsequent property enhancements in nanocomposites. POLYM. ENG. SCI., 52:2530-2536, 2012. © 2012 Society of Plastics Engineers, INTRODUCTION Polymer composites with carbon as filler materials exhibit improvement of electrical, thermal, and mechanical properties (1), (2). Among the various other carbon additives, graphite is much more attractive to [...]

Nylon 11 (PA11) nanocomposites with different loadings of multi-walled carbon nanotubes (MWNTs) were prepared by melt compounding. Scanning electron microscopy images on the fracture surfaces of the composites showed a uniform dispersion of MWNTs throughout the matrix. The presence of the MWNTs significantly improved the thermal stability and enhanced the storage modulus (G') of the polymer matrix. Melt rheology studies showed that, compared with neat PA11, the incorporation of MWNT into the matrix resulted in higher complex viscosities ([absolute value of η*]), storage modulus (G'), loss modulus (G'), and lower loss factor (tanδ). PA11 and its nanocomposites containing less than 1 wt% MWNTs showed similar frequency dependencies and reached a Newtonian plateau at low frequencies. For the nanocomposite with 2 wt% MWNTs, the regional network was destroyed and the orientation of the MWNTs during shearing exhibited a very strong shear thinning effect. The complex viscosities ([absolute value of η*]) of the nanocomposites are larger than that of neat PA11 and decreased with increasing the temperature. POLYM. ENG. SCI., 49:1063-1068, 2009. [C] 2009 Society of Plastics Engineers, INTRODUCTION Carbon nanotubes (CNTs) are considered to be one kind of ideal one-dimensional reinforcing tillers for fabricating high-performance polymer composites because of their nano-scale diameter, high aspect ratio, and unique [...]