Small Angle Neutron Scattering Studies of Single Phase IPNs

1992 ◽  
Vol 274 ◽  
Author(s):  
Barry J. Bauer ◽  
Robert M. Briber ◽  
Shawn Malone ◽  
Claude Cohen
Keyword(s):  
Phase Separation ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Crosslink Density ◽  
Single Phase ◽  
Polymer Networks ◽  
Interpenetrating Polymer Networks ◽  
Miscible Polymer Blends ◽  
Low Levels

ABSTRACTInterpenetrating polymer networks (IPNs) have been synthesized from polymers that form miscible polymer blends. Full, semi-I and semi-II IPNs made from polystyrene-d8 and poly(vinylmethylether) can be made to phase separate by incorporating low levels of crosslinking. However, blends of these polymers have a negative Flory-Huggins interaction parameter, making them highly miscible. This indicates that formation of IPNs favors phase separation relative to blends.IPNs made from polystyrene-d8 and polystyrene-h8 show that increased crosslink density also destabilizes the mixture as shown by small angle neutron scattering.IPNs have also been made by crosslinking end functionalized polydimethylsiloxanes in the presence of nonfunctionalized, deuterated siloxanes. These IPNs are also destabilized by increasing crosslink density, suggesting that the destabilization is due to the network, and not to the particular type of network forming reaction.

Small Angle Neutron Scattering Studies of Blends of Protonated Linear Polystyrene with Crosslinked Deuterated Polystyrene

1989 ◽  
Vol 171 ◽  
Author(s):  
Robert M. Briber ◽  
Barry J. Bauer
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Crosslink Density ◽  
Single Phase ◽  
Linear Chain ◽  
Free Energies ◽  
Scattering Function ◽  
Angle Scattering ◽  
Divinyl Benzene

ABSTRACTSmall angle neutron scattering (SANS) has been used to study the scattering function and thermodynamics of blends of linear protonated polystyrene (PSH) and crosslinked deuterated polystyrene (PSD). Two series of samples were synthesized. In both cases the samples were made by dissolving the linear PSH in deuterated (d8) styrene monomer containing a small amount of divinyl benzene as a crosslinker which was then polymerized to form the PSD network around the linear PSH chains. The samples were all made at a concentration of 50/50 by weight PSD/PSH. A special effort was made to keep the samples single phase so that SANS could be used to study the thermodynamics of the system and compare with theory. This entailed working at relatively low crosslink densities (<1 mole % crosslink units). Series 1 is a set of samples with the same crosslink density varying the length of the linear chain. Series 2 is a set of samples containing the same length linear chain varying the crosslink density systematically. By extrapolating S(q) obtained from SANS to q=O the zero angle scattering, S(O), was obtained. S(O) is inversely proportional to the second derivative of the free energy with respect to composition, ∂2 (Δf/kT)/∂ø2. Assuming additivity of the free energies of mixing and elasticity, the portion of the zero angle scattering due to elasticity is calculated.

scholarly journals Phase separation in titanium hydrides studied by small-angle neutron scattering

1993 ◽  
Vol 03 (C8) ◽  
pp. C8-287-C8-290 ◽  
Author(s):  
I. O. BASHKIN ◽  
A. I. KOLESNIKOV ◽  
V. Yu. MALYSHEV ◽  
E. G. PONYATOVSKY ◽  
S. BORBÉLY ◽  
...  
Keyword(s):  
Phase Separation ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering

Phase Separation In Blends of Polystyrene and Poly (P-METHYLSTYRENE) Using Thermal Analysis And Small-Angle Neutron Scattering

1993 ◽  
Vol 321 ◽  
Author(s):  
A. Xenopoulos ◽  
J. D. Londono ◽  
G. D. Wígnall ◽  
B. Wunderlich
Keyword(s):  
Thermal Analysis ◽  
Phase Separation ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Small Difference ◽  
Glass Transitions ◽  
Scanning Calorimetry ◽  
Reliable Detection ◽  
Sans Data

ABSTRACTDifferential scanning calorimetry (DSC) was used to study blends of polystyrene (PS) and poly (p-Methylstyrene) (PpmS). The presence of two glass transitions on heating after quenching was interpreted as evidence of phase separation at the temperature of the liquid before quenching. The small difference between the glass transitions of the homopolymers in the PS/PpmS system of “13 K limits the reliable detection of double glass transitions for blends to concentrations between 30 and 70%. The results of the DSC technique are supported by comparison with small angle neutron scattering (SANS) data.

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