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Composite Application (composite + application)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Covalent addition of diethyltoluenediamines onto carbon nanotubes for composite application

POLYMER COMPOSITES, Issue 8 2009
Shiren Wang
Diethyltoluenediamines (DETDA) was grafted to single-walled carbon nanotubes (SWNTs) through diazonium-based addition for improving dispersion and interfacial bonding in SWNT/epoxy nanocomposites. Characterization results of Fourier Transformed Infrared spectroscopy and Raman spectroscopy validated covalent bonding between DETDA and carbon nanotubes. The degree of functionalization was about 4% based on thermo-gravimetric analysis. Interfacial bonding strength was computed in the presence of chemical bonding and the computation results indicated that the interfacial shear strength in the presence of functionalized carbon nanotubes was significantly enhanced. The experimental test revealed that the tensile strength of nanocomposites was enhanced about 23% and Young's modulus about 25%, with 0.5 wt% loading of functionalized-nanotubes. These considerable improvements further verified the load-transfer enhancement in the functionalized-SWNTs/epoxy nanocomposites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

Potential biomarkers involving IKK/RelA signal in early stage non-small cell lung cancer

CANCER SCIENCE, Issue 3 2008
Xianqing Jin
The clinical relevance of nuclear factor ,B (NF-,B) and its regulatory molecules on prognosis of patient with early stages of non-small cell lung cancer (NSCLC), remains unclear. Therefore, we conducted biomarker analyses with survival in patients with stages I and II NSCLC. Tumor samples were collected from 88 patients with early-stage NSCLC (stages I, II). A minimum follow-up period of 5 years was required. RelA, phosphorylated I,B (pI,B,), pIKK,/, were detected by immunostaining. NF-,B DNA binding activity was assessed by electrophoretic mobility shift assay. Association of clinical and pathologic variables (e.g. sex, age, pathologic stage) with relevant molecules was determined by Pearson's ,2 test or Fisher's exact test. Survival analysis based on single expression of RelA, pI,B,, pIKK,/, as well as composite expressions were evaluated using Cox proportional hazards regression models, and log rank test followed Kaplan-Meier estimates. RelA, pI,B,, pIKK,/, were observed as increased expression in NSCLC tissues compared with adjacent normal tissues and normal lung tissues. These molecules were associated with tumor-node-metastasis stages, T stages and histological status, respectively. Among the molecules analyzed, RelA and pI,B,-positive were statistically significant predictors of patient death in the entire patient population adjusted by age, gender and smoking status; furthermore both RelA and pI,B,-positive was the strongest prognostic indicators of poor prognosis by univariate and multivariate analyses. Borderline positive correlations were observed between RelA and pI,B, or pIKK,/, expression. In this cohort of early-stage NSCLC patients, molecular markers, especially composite application of multiple biomarkers (both nuclear RelA and cytoplasmic pI,B-, expression) that independently predict overall survival have been identified. (Cancer Sci 2008; 99: 582,589) [source]

Reactive blending of functionalized acrylic rubbers and epoxy resins

POLYMER ENGINEERING & SCIENCE, Issue 9 2001
C. Dispenza
A high molecular weight acrylonitrile/butadiene/methacrylic acid (Nipol 1472) rubber is chosen to control processability and mechanical properties of a TGDDM (tetra glycidyl diphenyl methane) based epoxy resin formulation for aerospace composite applications. The physical blend of rubber and epoxy resin, achieved by dissolution of all the components in a common solvent, forms a heterogeneous system after solvent removal and presents coarse phase separation during cure that impairs any practical relevance of this material. A marked improvement of rubberepoxy miscibility is achieved by reactive blending (,pre-reaction') the epoxy oligomer with the functional groups present in the rubber. The epoxy-rubber ,adduct' so obtained appears as a homogeneous system at room temperature and also after compounding with the curing agent. Depending on the nature and extent of interactions developed between the rubber and the epoxy resin during ,pre-reaction,' materials with different resin flow characteristics, distinctive morphologies and mechanical properties after curing were obtained. The effect of ,pre-reaction' on the resin cure reaction kinetics has been also investigated. [source]

Large-scale extrusion processing and characterization of hybrid nylon-6/SiO2 nanocomposites

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 4 2004
Monserrat García
Abstract Solution impregnations, pulltrusion and film stacking are widely used methods to prepare thermoplastic composite materials. Extruders are used to melt the polymer and to incorporate fibers into the polymer in order to modify physical properties. In this article, the compounding of colloidal silica nanoparticles filled polyamide-6 (PA-6) is achieved using a twin-screw extruder, which has a significant market share due to its low cost and easy maintenance. The experiments were performed at 250 rpm and the bulk throughput was 6,kg,h,1 with a pump pressure of 30 bars. The composites were characterized with nuclear magnetic resonance (NMR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). As determined by WAXD, the PA-6 showed higher amounts of , -phase when compared to other synthesis methods such as in situ polymerization. TEM pictures showed that the silica particles aggregated nevertheless, upon addition of 14% (w/w) silica the E-modulus increased from 2.7 to 3.9,GPa indicating that an effective mechanical coupling with the polymer was achieved. The behavior, illustrated with dynamic mechanical analysis (DMA) curves, indicated that in general when a filled system is compared to unfilled material, the values of the moduli (E, and E,) increased and tan , decreased. Determination of molecular mass distribution of the samples by means of size exclusion chromatography (SEC) coupled to a refractive index (RI), viscosity (DV) and light scattering (LS) detector revealed that the addition of silica did not decrease the average molecular weight of the polymer matrix, which is of importance for composite applications. Copyright © 2004 John Wiley & Sons, Ltd. [source]