Differential scanning rubber

ATBN - amine terminated nitrile rubber X - Flory Huggins interaction parameter CPE - carboxylated polyethylene d - width at half height of the copolymer profile given by Kuhn statistical segment length DMAE - dimethyl amino ethanol r - interfacial tension reduction d - particle size reduction DSC - differential scanning calorimetry EMA - ethylene methyl acrylate copolymer ENR - epoxidized natural rubber EOR - ethylene olefin rubber EPDM - ethylene propylene diene monomer EPM - ethylene propylene monomer rubber EPR - ethylene propylene rubber EPR-g-SA - succinic anhydride grafted ethylene propylene rubber... 

Thermoanalytical techniques such as differential scanning calorimetry (DSC) and thermogravi-metric analysis (TGA) have also been widely used to study rubber oxidation [24—27]. The oxidative stability of mbbers and the effectiveness of various antioxidants can be evaluated with DSC based on the heat change (oxidation exotherm) during oxidation, the activation energy of oxidation, the isothermal induction time, the onset temperamre of oxidation, and the oxidation peak temperature. 

In order to obtain the degree of cure and rate of curing, we must first measure the reaction. This is typically done using a differential scanning calorimeter (DSC) as explained in Chapter 2. Typically, several dynamic tests are performed, where the temperature is increased at a constant rate and heat release rate (Q) is measured until the conversion is finished. To obtain Qt we must calculate the area under the curve Q versus t. Figure 7.17 shows four dynamic tests for a liquid silicone rubber at heating rates of 10, 5, 2.5 and 1 K/min. The trapezoidal rule was used to integrate the four curves. As expected, the total heat Qt is the same (more or less) for all four tests. This is to be expected, since each curve was represented with approximately 400 data points. 

Abbreviations y x AFM AIBN BuMA Ca DCP DMA DMS DSC EGDMA EMA EPDM FT-IR HDPE HTV IPN LDPE LLDPE MA MAA MDI MMA PA PAC PB PBT PBuMA PDMS PDMS-NH2 interfacial tension viscosity ratio atomic force microscopy 2,2 -azobis(isobutyronitrile) butyl methacrylate capillary number dicumyl peroxide dynamic mechanical analysis dynamic mechanical spectroscopy differential scanning calorimetry ethylene glycol dimethacrylate ethyl methacrylate ethylene-propylene-diene rubber Fourier transform-infra-red high density polyethylene high temperature vulcanization interpenetrating polymer network low density polyethylene linear low density polyethylene maleic anhydride methacrylic acid 4,4 -diphenylmethanediisocyanate methyl methacrylate poly( amide) poly( acrylate) poly(butadiene) poly(butylene terephtalate) poly(butyl methacrylate) poly(dimethylsiloxane) amino-terminated poly(dimethylsiloxane)... 

Poly(epichlorohydrin), CO rubber (Hydrin), was chosen for various reasons. The one reason was that CO has been shown to be miscible with PMMA by Anderson based upon differential scanning calorimetry (DSC) which showed only one glass transition temperature (T ) for the blend (9). Since T is very sensitive to the disruption of the local structure that results when two polymers are mixed, the existence of a single glass transition temperature is a good indicator of miscibility (10). 

Many relatively slow or static methods have been used to measure Tg. These include techniques for determining the density or specific volume of the polymer as a function of temperature (cf. Fig. 11-1) as well as measurements of refractive index, elastic modulus, and other properties. Differential thermal analysis and differential scanning calorimetry are widely used for this purpose at present, with simple extrapolative eorrections for the effects of heating or cording rates on the observed values of Tg. These two methods reflect the changes in specific heat of the polymer at the glass-to-rubber transition. Dynamic mechanical measurements, which are described in Section 11.5, are also widely employed for locating Tg. 

Burfield, D. R. and K. L. Ldm, Differential scanning calorimetry analysis of natural rubber and related polyisoprenes. Measurement of the glass transition temperature. Macromolecules, 16, 7, 1170-1175, 1983. 

Fracture-Energy Testing. Table I gives the recipes and the fracture energies measured under slow and fast rates of test, for the elastomer-modified VER and for ETBN additions to the elastomer-modified VER. Also given are the total amounts of reactive liquid rubber, from both ETBN addition and CTBN reacted directly into the VER, for each recipe. For reference, the unmodified VER has a slow GIc. of 0.11 kj/m2. Finally, the Tg obtained from differential scanning calorimetric measurements is given for each recipe. 

Based on their differential scanning calorimetry results. Rubbering et al. [75RAB/WAN] reported A 77 = (6.53 0.17) kJ-mol for the reaction ... 

Figure 12, Brillouin splittings Aw d vs, temperature near the glass-rubber relaxation for PMMA, 10,000 molecular-weight PS and 2100 molecular-weight polystyrene. The arrows indicate the value of T(g) determined uHth a differential scanning calorimeter.

Sircar A.K. and J.L. Wells. 1982. Thermal conductivity of elastomer vulcanizates by differential scanning calorimetry. Rubber Chem. Technol. 55 191—207. 

Figure 2 shows the SVM images for the PS film collected at various temperatures from 200 to 400 K [23]. The surface modulus of the silicon substrate should be invariant with respect to temperature in the employed range, meaning that the contrast enhancement between the PS and Si surfaces with temperature reflects that the modulus of the PS surface starts to decrease. In the case of a lower temperature, the image contrast was trivial, as shown in the top row of Fig. 2. On the other hand, as the temperature went beyond 330 or 340 K, the contrast between the PS and Si surfaces became remarkable with increasing temperature. This makes it clear that the PS surface reached a glass-rubber transition state at around these temperatures. Here, it should be recalled that the T of the PS by differential scanning calorimetry (DSC) was 378 K. Therefore, it can be claimed that surface glass transition temperature (7 ) in the PS film is definitely lower than the corresponding T. ...

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