Solvent swelling, crosslinked

Fig. 1. Solvent swelling experiments with ECA polymers crosslinked with 7.

Solvent swelling experiments, with CH2CI2 and ECA polymer crosslinked with 7, demonstrate that the addition of a difunctional cyanoacrylate monomer does improve solvent resistance [6], shown in Fig. 1. 

Solvent Swelling and Extraction, The residue samples were extracted with pyridine at the boiling point to obtain the amount and composition of the extract. A portion of the dried, extracted solids was swelled in pyridine in order to estimate the density of crosslinks introduced by the preliquefaction process. The solvent swelling measurements were carried out according to the method of Green et al. (30,31). 

Question 4. Why is the preliquefied insoluble product so easily liquefied The most probable answer. The preliquefaction product with the reduced carboxyl groups content is more easily liquefied than the parent coal. Based on the product distribution, solvent swelling data and the model simulation, this improvement results from a reduction in the CO2 associated crosslinks and from the bond breaking which produces the chloroform solubles. Both effects reduce the total number of bonds linking the network so that the coal can become fluid. If the chloroform soluble fraction is removed after preliquefaction and the residue liquefied, the drastic improvement in the liquefaction is not observed. The model simulation confirms that the residue alone will liquefy slightly better than the parent coal, but not nearly as well as the mixture. 

Another important property of open-cell PolyHIPE materials is their ability to absorb large quantities of solvent, by capillary action [128]. Simply immersing a piece of the material in the liquid causes absorption, with displacement of the air from inside the matrix. This occurs until all voids are filled. The nature of the liquid will affect the volume which can be taken up [133]. Methanol, which is a non-swelling solvent for crosslinked polystyrene, is absorbed to a lesser... 

Macromolecular 10-100 nm Network chains/strands, crosslinks network defects (dangling chains) Macro- molecular science Rubber elasticity, solvent swelling... 

Manatt SL, Horowitz D, Horowitz R, Pimnell RP, Solvent swelling for enhancement of carbon-13 nuclear magnetic resonance spectral information from insoluble polymers chloromethylation levels in crosslinked, Anal. Chem., 52 1529-1532, 1980. 

Many different methods can be used to measure the degree of crosslinking within an epoxy specimen. These methods include chemical analysis and infrared and near infrared spectroscopy. They measure the extent to which the epoxy groups are consumed. Other methods are based on the measurements of properties that are directly or indirectly related to the extent and nature of crosslinks. These properties are the heat distortion temperature, glass transition temperature, hardness, electrical resistivity, degree of solvent swelling and dynamic mechanical properties, and thermal expansion rate. The methods of measurement are described in Chap. 20. 

For a negative resist, a contrast curve also can be consuiicted (Fig. 2). In a crosslinked system, the time of development should not alter the curve since extraction of sol from the thin film network is voy rtq>id. Contrast is defined now as (1/slope). A problem with all polymer resists, but especially acute with negative ones, is that of distortion of the remaining pattern by solvent swelling during development... 

EGDMA, ALMA, etc. Intraparticle crosslinking for solubility control, reduction of thermoplastic flow, solvent swelling resistance. 

Padden (1964) have employed the freezing point depression of solvent-swelled NR-BR blends to determine the crosslink densities of the individual polymer phases. The freezing point depression of a solvent in a swollen vulcanizate is dependent on the volume fraction of solvent in the elastomer phase. 

Fig. 13. Swelling dependence of the ratio of the activities of the solvent in crosslinked and uncrosslinked polymers O experimental results by Brotzman and Eichin-ger (sample EL2) swelling equilibrium. Theories with equal mixing contributions in crosslinked and uncrosslinked...

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