Classification of homogeneous copolymers of propylene and 1‐octene based on comonomer content

Abstract

The solid‐state structure and properties of homogeneous copolymers of propylene and 1‐octene were examined. Based on the combined observations from melting behavior, dynamic mechanical response, morphology with primarily atomic force microscopy, X‐ray diffraction, and tensile deformation, a classification scheme with four distinct categories is proposed. The homopolymer constitutes Type IV. It is characterized by large α‐positive spherulites with thick lamellae, good lamellar organization, and considerable secondary crystallization. Copolymers with up to 5 mol % octene, with at least 28 wt % crystallinity, are classified as Type III. Like the homopolymer, these copolymers crystallize as α‐positive spherulites, however, they have smaller spherulites and thinner lamellae. Both Type IV and Type III materials exhibit thermoplastic behavior characterized by yielding with formation of a sharp neck, cold drawing, strong strain hardening, and small recovery. Copolymers classified as Type II have between 5 and 10 mol % octene with crystallinity in the range of 15–28%. Type II materials have smaller impinging spherulites and thinner lamellae than Type III copolymers. Moreover, the spherulites are α‐negative, meaning that they exhibit very little crystallographic branching. These copolymers also contain predominately α‐phase crystallinity. The materials in this category have plastomeric behavior. They form a diffuse neck upon yielding and exhibit some recovery. Type I copolymers have more than 10 mol % octene and less than 15% crystallinity. They exhibit a granular texture with the granules often assembled into beaded strings that resemble poorly developed lamellae. Type I copolymers crystallize predominantly in the mesophase. Materials belonging to this class deform with a very diffuse neck and also exhibit some recovery. They are identified as elastoplastomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4357–4370, 2004

Metallocenic Copolymers of Isotactic Propylene and 1‐Octadecene: Crystalline Structure and Mechanical Behavior

“…A gradual change from lamellar to bundlelike crystals seems to be observed as comonomer is further increased in the CiPOD2.3 copolymer (bottom right picture), since the crystallizable length sequences do not become sufficiently long to form chain folds. Analogous changes in morphological characteristics have also been found in copolymers of propylene with 1-octene, [26] though in those copolymers, higher contents of 1-octene are required for a given feature, pointing out the influence of length of the pendant aliphatic chains on incorporated units. Figure 4 shows the stress-strain behavior of the homopolymer and the five copolymers synthesized.…”

“…However, the studies of copolymers of propylene and large olefins are relatively few in open literature, though some publications on these copolymers can be found. [19][20][21][22][23][24][25][26] Therefore, the objective of this work is to show the effect of the incorporation of one type of long-chain a-olefin, 1-octadecene, in the final properties of copolymers with isotactic propylene synthesized with a metallocene catalyst. In particular, the influence of comonomer content on the structural and thermal characterization and on the viscoelastic and mechanical response of copolymers is studied.…”

Overall crystallization kinetics of polymorphic propylene–ethylene random copolymers: A two-stage parallel model of Avrami kinetics

“…(15). Numerical simulations with classical nucleation and growth models appropriate to the development of a and g crystallinities provide meaningful solutions and kinetic parameters for both crystallization stages.…”

“…The Table 2 Fraction of alpha phase (w a ) and kinetic parameters from non-linear regression fits of experimental data with Eq. (15) Sample T c ( C) w a n K a  10 3 (min Àn ) The SSD values in parenthesis correspond to m ¼ 3. Experimental data and results are shown in Fig.…”

Relationship of polymorphic crystalline phase texture to strain recovery and stiffness of a propylene‐based elastomer

“…In this case, a network of rubbery, amorphous polymer chain segments is anchored by crystals. The crystallizable chain segments in olefin‐based TPEs are usually polyethylene or polypropylene sequences 3–6…”