Classification of ethylene-styrene interpolymers based on comonomer content

Abstract

ABSTRACT:Copolymerization of ethylene and styrene by the INSITE™ technology from Dow presents a new polymer family identified as ethylene-styrene interpolymers (ESI). Based on the combined observations from melting behavior, density, dynamic mechanical response, and tensile deformation, a classification scheme with 3 distinct categories is proposed. Polymers with up to 50 wt % styrene are semicrystalline and are classified as type E. The stress-strain behavior of low-crystallinity polymers at ambient temperature exhibits elastomeric characteristics with low initial modulus, a gradual increase in the slope of the stress-strain curve at higher strains, and large instantaneous recovery. The structural origin of the elastomeric behavior is probably a network of flexible chains with fringed micellar crystals serving as multifunctional junctions. Polymers with more than 50 wt % styrene are amorphous. Because the range of glass transition temperatures encompasses ambient temperature (nominally 25°C), it is useful to differentiate ESIs that are above the glass transition as type M and those that are below the glass transition as type S. Type M polymers behave as rubber-like liquids. They have the lowest modulus and lowest stress levels. Some elastic characteristics are attributed to the entanglement network. Type S polymers exhibit large strain rate sensitivity with glassy behavior at short times and rubbery behavior at longer times. The term ''glasstomer'' is coined to describe these polymers. The division between type M and type S is based on chain dynamics, rather than solid state structure, and thus depends on the temperature of interest. At ambient temperature, ESIs with 50 to 70 wt % styrene are classified as type M; polymers with more than 70 wt % styrene are classified as type S.

Materials Properties Derived from INSITE Metallocene Catalysts

“…[25,27] The relaxation processes associated with this loss peak are complex in nature. There is an increasing contribution of the socalled a-relaxation for polymers of high crystallinity.…”

A Closed‐Loop Phase Diagram in a Weakly Interacting Polyolefin Copolymer Binary Blend System

“…Consequently, PES thus produced can range from crystalline thermoplastics to elastomers, and could be used as functional materials, such as adhesives, or used in structural blends/alloys. Baer, Hiltner, and coworkers, [10][11][12] and other scientists from Dow Chemical Co. [13][14][15][16][17] have carried out a series of studies on the catalysis, synthesis, structure, and properties of ethylene-styrene copolymers. However, an in-depth study on the equilibrium and kinetics of phase behaviors and crystallization kinetics is still lacking.…”

Syndiospecific Styrene Polymerization and Ethylene/Styrene Copolymerization Using Half-Titanocenes: Ligand Effects and Some New Mechanistic Aspects

“…), as described below [40][41][42][43][44][45][46]. Ethylene/styrene copolymers, which can not be prepared by conventional (free radical, Ziegler-Natta) processes [47][48][49][50][51][52][53], also attract considerable attention due to their promising properties [54][55][56]. Styrene incorporation into the PE backbone results in drastic changes in the viscoelastic behavior as well as thermo-mechanical properties of the polymeric material [55], since the crystallizability of PE chains is gradually inhibited by the incorporation of styrene.…”

“…Styrene incorporation into the PE backbone results in drastic changes in the viscoelastic behavior as well as thermo-mechanical properties of the polymeric material [55], since the crystallizability of PE chains is gradually inhibited by the incorporation of styrene. The copolymers range from semi-crystalline to amorphous materials, depending on the styrene content [54]. Therefore, these copolymers can become effective blend compatibilizers for PS/PE blends, and also have potential in foam, film and sheet applications.…”

“…As described below, the microstructures for the resultant copolymers depend on the catalysts used. The glass transition temperature (T g ) as measured by differential scanning calorimetry (DSC) increased with an increase in the styrene content, because, as described above, the crystallizability of PE chains is gradually inhibited by the incorporation of styrene, and the copolymers are semi-crystalline to amorphous materials, depending on the styrene content [54].…”