Crystallization analysis fractionation: A new technique for the analysis of branching distribution in polyolefins

Abstract

SYNOPSISA new technique to analyze the short-chain branching distribution (SCBD) in linear lowdensity polyethylene has been developed. The technique referred as crystallization analysis fractionation is based on a stepwise precipitation approach. By monitoring the polymer solution concentration during crystallization, the cumulative and differential SCBD can be obtained without the need of physical separation of fractions. The new technique has been shown to provide similar results to temperature rising elution fractionation but in a shorter time and with a simplified apparatus. It allows the simultaneous analysis of various samples and could also be used for analysis of polypropylene and other semicrystalline polymers that can be fractionated on the basis of crystallizability. 0 1994 John Wiley & Sons, Inc.

Polyolefin analysis by single-step crystallization fractionation

“…1,2,11 It has been shown that CRYSTAF and TREF results are similar. However, one of the advantages of CRYSTAF is that the analysis time is much shorter than the one required by TREF.…”

“…The fractionation procedure was as follows: (1) cooling from 140°C to 65°C (collecting samples between 100°C to 65°C), (2) heating to 140°C, and (3) cooling from 140°C to 30°C (collecting sample between 60°C to 30°C). The intermediate heating step is needed to redissolve polymer crystals precipitated on the filters.…”

Analytical Rheology of Polymer Melts: State of the Art

“…Ultimate mechanical properties and crack resistance improve as the length of the side branch increases, possibly because SCB influences morphology and tie-molecule concentration, requiring greater energy to be absorbed to initiate cracks [33]. SCB is usually detected and quantified using analytical techniques like solution differential scanning calorimetry (DSC), temperature rising elution fractionation (TREF), and crystallization analysis fractionation (CRYSTAF) [34][35][36][37][38][39].…”

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

“…The fractionation principle of this technique is already published in the literature [33][34][35]. The sample solution of concentration 0.1% (w/w) was prepared in 1, 2, 4 trichlorobenzene (TCB) at 160°C under stirring for 60 min.…”