Dynamic mechanical spectroscopy blends

The first data on polymer systems were collected via (laser-) light-scattering techniques [1] and turbidity measurements, further developed by Derham et al. [2,3]. Techniques based on the glass-transition of the polymer-blend constituents were also tested, such as DSC, Dynamic Mechanical Spectroscopy, and Dielectric relaxation [4]. Films made from solutions of... 

Marie et al. [49] also studied the in-situ block copolymer formation via reactive blending of functionalized homopolymers. In their work, blends were characterized by SEM, DSC and dynamic mechanical spectroscopy (DMS). It should be noted that their blends (PA-6/PDMS and PS/PDMS) were composed totally using functionalized homopolymers. The different reactions under investigation were amine(NH2)/anhydride(An), amine(NH2)/epoxy(E) and carboxylic acid(COOH)/epoxy(E) (Fig. 5). 

Characterization by DMS and DSC. Although characterization of small-strain viscoelastic and stress-strain behavior is not yet complete, preliminary dynamic mechanical spectroscopy (DMS) and differential scanning calorimetry (DSC) data were obtained for the blends having the highest and lowest molecular weights. 

Some cellulose derivatives and P(3HB) and P(3HB-co-3HV) have been found to show good compatibility [114-116]. These are chemically modified natural and natural biodegradable polymer blend systems. Blends obtained by melts compounding P(3HB) with cellulose acetate butyrate (CAB, degrees of butyrate and acetate substitution are 2.50 and 0.18, respectively) have been found to be miscible over the whole composition range by DSC and dynamic mechanical spectroscopy [116]. 

Figure 6.12. Dynamic mechanical spectroscopy results for blend of separate core/shell latex film 1/1 A/C and 1/1 B/C at a 1/1 blend ratio A = P(Bd/S), B = P(EHMA/S), and C = SAN. More distinctive glass transitions are shown here, particularly for polymer B.

Effects of addition of a compatibilizing block copolymer, poly(styrene-b-methyl methacrylate), P(S-b-MMA) on the rheological behavior of an immiscible blend of PS with SAN were studied by dynamic mechanical spectroscopy [Gleisner et al., 1994]. Upon addition of the compatibilizer, the average diameter of PS particles decreased from d = 400 to 120 nm. The data were analyzed using weighted relaxation-time spectra. A modified emulsion model, originally proposed by Choi and Schowalter [1975], made it possible to correlate the particle size and the interfacial tension coefficient with the compatibilizer concentration. It was reported that the particle size reduction and the reduction of occur at different block-copolymer concentrations. 

Figure 3.12 Dynamic mechanical spectroscopy of LDPE-EP rubber blend in tensile mode using synthetic frequency multiplexing of 1, 2, 5, 10, and 20 Hz.

Figure 7.11 Schematic showing the experimental probe size relative to the domain size in a polymer blend when using electron microscopy and dynamic mechanical spectroscopy to determine polymer miscibility. (Reprinted from Kaplan, Journal of Applied Polymer Science 20 2615. Copyright 1976, with permission from John Wiley Sons.)...

Polymer blends are of great interest from both industrial and fundamental aspects [1]. The glass transition temperature, Tg, is an important parameter for characterizing the physical properties of polymer blends. [2] Generally, Tg of the mixture becomes broader than its pure components [3-8]. The broadening of the transition is also accompanied with broader relaxation spectra as revealed from NMR [3], dynamic mechanical spectroscopy [4], and dielectric spectroscopy [5] measurements. Clusters with different motilities, or the so called dynamic heterogeneity, are suggested to be the main cause for these observations [5,6,9,10]. 

Transition metal coordination of Cu(II) carboxylate groups and pyridine groups was employed as a means of coupling a telechelic butadiene-base polymer with a randomly functionalized styrenic polymer. Dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) indicated partial miscibility of the two polymers and Fourier transform infrared (FTIR) spectroscopy demonstrated that interactions occurred on a molecular level. When compared with blends of PSVP and the free acid derivative of CTB, the compositions based on the transition metal complex had improved dimensional stability at elevated temperatures, though there remains some question as to the stability of the copper salt to hydrolysis. Electron spin resonance (ESR) spectroscopy showed that only the... 

Fire relstance,chemical composition by infrared (IR) and nuclear magnetic resonance (Mlffit) spectroscopy, thermal analyses, Clash-Berg moduli determination and dynamical mechanical analyses were determined. The fluorenone polyesters were spun as fibers from solution. They were blended with an acetylene terminated fluorenone monomer for plasticization and crosslinking at high temperatures to form an improved thermally stable product. 

Yan et al. [52] explored the use of IPN techniques to produce a composite vinyl-acrylic latex. The first-formed polymer was produced using VAc and divinyl benzene (DVB), while the second formed polymer constituted a BA/DVB copolymer. In both cases the DVB was added at 0.4 wt%. They compared this product with another product, a bidirectional interpenetrating netwodc (BIPN) in which VAc was again polymerized over the first IPN. They noted that the compatibility between the phases was more pronounced in the BIPN than in the IPN as determined using dynamic mechanical measurements and C nuclear magnetic resonance spectroscopy. The concept of polymer miscibility has also been used to produce composite latex particles and thus modify the pafamance properties of VAc latexes. Bott et al. [53] describe a process whereby they bloid VAc/ethylene (VAc/E) copolymers with copolymers of acrylic acid or maleic anhydride and determine windows of miscibility. Apparently an ethyl acrylate or BA copolymer with 10-25 wt% AA is compatible with a VAc/E copolymer of 5-30 wt% ethylene. The information obtained from this woik was then used to form blends of latex polymers by polymerizing suitable mixtures of monomers into preformed VAc/E copolymers. The products are said to be useful for coating adhesives and caulks. 

Composition profiles generated by interdiffusion in the concentrated regime between polyphenylene oxide-polystyrene blend pairs were experimentally determined by two techniques. Three-point bending moment measurements over a convenient temperature range (dynamic mechanical analysis (DMA)) were used to determine interphase composition profiles. Confocal micro-Raman spectroscopy was also used to measure local compositions along a direction which was perpendicular to the original interface. The study included some limiting cases to test accuracy, precision and flexibility of the DMA method. 4 refs. 

The unique capabilities of solid-state deuteron NMR (as well as experiments with N and result from the ability to assess ordering and mobility of individual bonds in a solid material. One can specifically examine the molecular mechanisms that determine bulk properties. This ability has motivated deuteron studies of such fundamental issues as the nature of the glass-transition [10-18] interactions in blends and mixtures [19-26], the molecular ordering and dynamics of crystalline materials [10,11,27-31] dynamics of elastomers [32-45], dielectric properties [46,47] and mechanical spectroscopy [48-51]. New experiments continue to be tied to methods development, particularly in the areas of multi-dimensional NMR [10,11,46, 52-61]. Recently, deuteron NMR has been employed in the characterization of new materials, for example for new liquid crystalline polymers [62-84],... 

Thermal analysis techniques are used to study the properties of polymers, blends and composites and to determine the kinetic parameters of their stability and degradation processes.Here the property of a sample is continuously measured as the sample is programmed through a predetermined temperature profile. Among the most common techniques are thermogravimetry (TG) and differential scanning calorimetry (DSC). Dynamic mechanical analysis (DMA) and dielectric spectroscopy are essentially extensions of thermal analysis that can reveal more subtle transitions with temperature as they affect the complex modulus or the dielectric function of the material. 

Our work has focused on high methoxyl pectin. In our studies we have investigated the preparation of plasticized and unplasticized pectin films, both with starch and with poly(vinyl alcohol), and characterized them using dynamic mechanical analysis, tensile measurements, scanning electron microscopy, solubility, and Fourier transfer infirared spectroscopy (4, 5, 6, 7, 8, 9, 10). We have also investigated the extrusion and characterization of pectin/starch blends (11). 

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