Reinforcing thermosets with crystallizable solvents

Abstract

This study demonstrates an approach to generate reinforcement in thermosetting polymers through crystal growth of crystallizable solvents. Emphasis is to identify the reaction conditions, which lead to suitable reinforcement in selected compounds. Crystallization behavior and miscibility of dimethylsulfone (DMS) in diglycidylether of bisphenol‐A epoxy monomer was investigated. Small angle laser scattering and optical microscopy were utilized to monitor phase separation and crystallization of DMS at different isothermal conditions during the cure process. It is shown that DMS crystals grow anisotropically to form faceted geometries and demonstrate possible structures to anchor into the epoxy matrix. The growth mechanism and the agility of crystals are shown to be affected by the cure reaction as well as depth of supercooling. A completely cured sample with 15 wt % DMS shows a broad map of rich morphologies from nanoscale particles to uniformly distributed macroscale, discontinuous fiber‐like crystals generated only by altering the curing conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 840–849, 2010

Reinforcing and toughening of polypropylene with self‐assembled low molar mass additives

“…Filler agglomeration was minimal and the reinforcing domains are spherical in the bulk. It is important to note this spherical geometry of the LMW organo‐metallic domains because organic crystals usually grow in faceted geometries, as previously shown by our group [4, 19, 20]. Regarding the interface between the particle and the matrix, and particle debonding from the matrix, the circular morphology and geometry of the fillers is significant under an applied load.…”

Reinforcing thermosets using crystalline desoxyanisoin structures

“…The loop in the exotherm forms due to rapid crystallization and associated self‐heating resulting from this process . Rapid crystallization behavior and the ability to recrystallize after melting are important characteristics for in‐situ thermoset reinforcement as seen Yordem et al work …”

“…Miscibility and cloud point experiments were carried out with small angle light scattering (SALS). Detailed SALS set up is reported elsewhere . A sample was placed into the heating stage and as a sample was heated and cooled at 10°C/min, data from scattering image, time, temperature and intensity were recorded simultaneously.…”

“…Upon cooling, TIPS takes place, which results in morphology that improves polymer mechanical properties of iPP . Another example of using this approach was demonstrated by Yordem et al The authors used a LMW crystallizable additive dimethylsulfone (DMS) to show that RIPS of DMS in diglycidylether of bisphenol‐A (DGEBA) epoxy monomer produced unique composites with distinct reinforcement morphologies …”

“…5,6 Another example of using this approach was demonstrated by Yordem et al The authors used a LMW crystallizable additive dimethylsulfone (DMS) to show that RIPS of DMS in diglycidylether of bisphenol-A (DGEBA) epoxy monomer produced unique composites with distinct reinforcement morphologies. 7 This study investigates using desoxyanisoin, which is a precursor to making a non-halogenated flame retardant molecule 4,4bishydroxydeoxybenzoin (BHDB), as a LMW additive for epoxy thermoset. Prior research showed that incorporation of BHDB into the polymer backbone as a replacement for bisphenol-A leads to improved flammability properties.…”