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DSC Results (dsc + result)

Distribution by Scientific Domains

Polymers and Materials Science	80%

Selected Abstracts

Synthesis of Carrier-Transporting Dendrimers with Perylenebis(dicarboximide)s as a Luminescent Core

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2006
Jianfeng Pan
Abstract Well-defined, modular dendrimers enable processing techniques and electronic properties to be tuned independently. Moreover, the dendritic topology can isolate the core chromophore, thus reducing or eliminating strong intermolecular interactions. This paper presents the synthesis of three series of flexible, dendron-functionalized dendrimers as red-light-emitting materials by a convergent approach: (1) carbazole (CZ) or oxadiazole (OXZ) terminated imide-type dendrimers, (2) cascade energy-transferring imide-type dendrimers, and (3) CZ-terminated perylene bay-type dendrimers. They all consist of the luminescent core of perylenebis(dicarboximide)s with specific functional groups of CZ or OXZ at the periphery and are constructed from flexible Fréchet-type poly(aryl ether) dendrons. The chemical structures of the dendrons and dendrimers were determined by standard spectroscopic techniques including 1H and 13C NMR spectroscopy and low/high-resolution mass spectrometry (ESI or MALDI-TOF). The dendrimers are designed on the basis of the following considerations: (1) dendron functionalization to incorporate CZ or OXZ units to realize the carrier-injection adjustment, (2) tuning or improving solubility, functionality, glass-transition temperature (Tg) with well-defined dendrons, and (3) avoiding luminescence quenching with the help of high site-isolation of dendrons to enhance core luminescence. DSC results indicate that the incorporation of Fréchet-type poly(aryl ether) dendrons can improve the amorphous properties and increase Tg. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Studies on glass transition temperature of mono and bilayer protein films plasticized by glycerol and olive oil

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008
Babak Ghanbarzadeh
Abstract Thermomechanical and thermal properties of whey protein, maize prolamin protein (zein), and the laminated whey protein,zein films were studied. The dynamic mechanical (thermal) analysis (DMTA) results showed that the single zein film had higher Tg than single whey protein and zein,whey laminated films. The shift in the Tg values of films from 31.2°C in whey protein film and 88.5°C in the zein film to 82.8°C in the laminated whey protein,zein films may be implied some interaction formation between the two polymers. The small tan , peaks were observed at ,50°C in zein,glycerol films and at ,22.37°C in the whey protein films and can be related to ,-relaxation phenomena or presence of glycerol rich region in polymer matrix. Zein-olive oil and zein,whey protein,olive oil films showed tan , peaks corresponded the Tg values at 113.8, and 92.4°C, respectively. Thus, replacing of glycerol with olive oil in film composition increased Tg. A good correspondence was obtained when DSC results were compared with the tan , peaks in DMTA measurements. DSC thermograms suggested that plasticizers and biopolymers remained a homogeneous material throughout the cooling and heating cycle. The results showed that Tg of zein,glycerol films predicted by Couchman and Karasz equation is very close to value obtained by DSC experiments. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Poly(vinyl alcohol)/Clay-Based Nanocomposite Hydrogels: Swelling Behavior and Characterization

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2007
Caio M. Paranhos
Abstract Polymer/clay composite hydrogels were prepared based on PVA hydrogels containing 3,10 wt.-% MOM. Their microstructure and morphology were studied by FT-IR, WAXS and SEM, whereas the interactions between MOM and PVA were evaluated by thermal analyses. The swelling ratios for the PVA/MOM hydrogels decrease with increasing MOM content. WAXS results indicate that MOM was intercalates, and DSC results show a strong interaction between PVA and MOM. This interaction results in a stable network, which is confirmed by the elastic modulus and the thermal decomposition behavior of the hydrogels. Therefore, MOM acts as a co-crosslinker, improving the stability of the network. [source]

Polymorphic behavior of nylon 6/saponite and nylon 6/montmorillonite nanocomposites

POLYMER ENGINEERING & SCIENCE, Issue 6 2002
Tzong-Ming Wu
X-ray diffraction methods and DSC thermal analysis have been used to investigate the structural change of nylon 6/clay nanocomposites. Nylon 6/clay has prepared by the intercalation of ,-caprolactam and then exfoliaton of the layered saponite or montmorillonite by subsequent polymerization. Both X-ray diffraction data and DSC results indicate the presence of polymorphism in nylon 6 and in nylon 6/clay nanocomposites. This polymorphic behavior is dependent on the cooling rate of nylon 6/clay nanocomposites from melt and the content of saponite or montmorillonite in nylon 6/clay nanocomposites. The quenching from the melt induces the crystallization into the , crystalline form. The addition of clay increases the crystallization rate of the , crystalline form at lower saponite content and promotes the heterophase nucleation of , crystalline form at higher saponite or montmorillonite content. The effect of thermal treatment on the crystalline structure of nylon 6/clay nanocomposites in the range between Tg and Tm is also discussed. [source]

Crystallinity, thermal properties, morphology and conductivity of quaternary plasticized PEO-based polymer electrolytes

POLYMER INTERNATIONAL, Issue 3 2007
Yan-Jie Wang
Abstract Quaternary plasticized solid polymer electrolyte (SPE) films composed of poly(ethylene oxide), LiClO4, Li1.3Al0.3Ti1.7(PO4)3, and either ethylene carbonate or propylene carbonate as plasticizer (over a range of 10,40 wt%) were prepared by a solution-cast technique. X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) indicated that components such as LiClO4 and Li1.3Al0.3Ti1.7(PO4)3 and the plasticizers exerted important effects on the plasticized quaternary SPE systems. XRD analysis revealed the influence from each component on the crystalline phase. DSC results demonstrated the greater flexibility of the polymer chains, which favored ionic conduction. SEM examination revealed the smooth and homogeneous surface morphology of the plasticized polymer electrolyte films. EIS suggested that the temperature dependence of the films' ionic conductivity obeyed the Vogel,Tamman,Fulcher (VTF) relation, and that the segmental movement of the polymer chains was closely related to ionic conduction with increasing temperature. The pre-exponential factor and pseudo activation energy both increased with increasing plasticizer content and were maximized at 40 wt% plasticizer content. The charge transport in all polymer electrolyte films was predominantly reliant on lithium ions. All transference numbers were less than 0.5. Copyright © 2006 Society of Chemical Industry [source]