Effect of Comonomer Type

The effect of comonomer type was studied by Brull et al. [59] using propylene/1-olefin copolymers with several comonomer types (1-octene, 1-decene, 1-tetradecene, and 1-octadecene). They reported that, for their set of samples, not only Crystaf peak temperatures but also melting and crystallization temperatures measured by DSC were independent of comonomer type but depended strongly on comonomer content. 

More recent work by the same research group [60] has investigated the effect of comonomer type using a series of ethylene/1-olefin copolymers (1-decene, 1-tetradecene, and 1-octadecene). Notice that ethylene instead of propylene was used in this particular study. Once more, they reported that Crystaf peak temperatures were practically independent of comonomer type (Fig. 35). 

These two results are interesting because earlier work by da Silva Filho et al. [49] showed that ethylene/1-butene and ethylene/1-octene copolymers had significantly different crystallization temperatures for the same 

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Fig. 12 Effect of comonomer type on Tref calibration curves [28]...

In our recent work [67], we investigated the effect of comonomer type on CO crystallization using a series of ethylene/1-olefin copolymers with four comonomer types propylene, 1-hexene, 1-octene, and 1-dodecene. Four blends, one for each copolymer type, were prepared such that they crystallized at the same temperature range and had similar ATq to ehminate the effect of similarity of chain crystalHzabihties. The Crystaf results of these blends indicated that the comonomer type of the parent samples did not appreciably influence their cocrystalHzation behavior, as illustrated in Fig. 39. 

Fig. 39 Effect of comonomer type on cocrystallization at a cooling rate of 0.1 °C/min for blends with the same comonomer type. BPED blend of ethylene/1-dodecene copolymers, BPEO blend of ethylene/l-octene copolymers BPEH blend of ethylene/1-hexene copolymers, BPEP blend of ethjdene/propylene copolymers [67]...

Table 2.2 Effect of Comonomer Type on Physical Properties...

The effect of different types of comonomers on varies. VDC—MA copolymers mote closely obey Flory s melting-point depression theory than do copolymers with VC or AN. Studies have shown that, for the copolymers of VDC with MA, Flory s theory needs modification to include both lamella thickness and surface free energy (69). The VDC—VC and VDC—AN copolymers typically have severe composition drift, therefore most of the comonomer units do not belong to crystallizing chains. Hence, they neither enter the crystal as defects nor cause lamellar thickness to decrease, so the depression of the melting temperature is less than expected. 

Fig. 34 Effect of comonomer content on Crystaf profiles. These samples are ethylene/ 1-hexene copolymers synthesized using a single-site-type catalyst. All samples have similar molecular weights [58]...

In this study, we examined the copolymerization of propylene with 1-butene and 1-pentene in liquid propylene medium in the presence of a highly active isospecific homogeneous a 5o-metallocene catalyst with the C -symmetry, rac-Me2Si(4-Ph-2-MeInd)2ZrCl2, activated by methyl-aluminoxane (MAO). The effects of the type of comonomer on the rate of copolymerization and the molecular mass characteristics, microstructure, thermophysical, and mechanical properties of the copolymers are investigated. The results of this study are compared with the data obtained with the same system used for the copolymerization of propylene with ethylene, 1-hexene, and l-octene. ... 

Copolymers are macromolecules composed of two or more chemically distinct monomer units, covalently joined to form a common polymer chain [1,2], In these materials, the sequence distribution of the monomer counits plays a critical role in determining the copolymer s crystallization behavior, and consequently influences its solid-state morphology and material properties [1,2], At one extreme, different types of monomer units may be randomly incorporated into the polymer chain, resulting in a statistical copolymer. At the other extreme, blocks of homopolymer sequences of different chemical nature and chain length may be joined together to form what is known as a block copolymer. In this chapter, we wiU review the key effects of comonomer incorporation on the solid-state morphology and crystallization kinetics in both statistical and block copolymers. 

The composition of copolymer and distribution of units in copolymer molecule can be predicted as follows. Let us designate two types of comonomer molecules as A and B and the respective radicals as A and b1 The symbols with an asterisk deal with the process proceeding on the template. In addition, let us assume that we can neglect the penultimate effect. In this case, the process of propagation is expressed by the following set of reactions and respective rates and rate constants ... 

In addition to a-olefins, p-/-butylstyrene can be used as a comonomer for the isotactic specific copolymerization with carbon monoxide with chiral induction [32], Whereas bipyridyl as ligand gives a syndiotactic polymer, the Pd-catalyzed polymerization with ligand 11 leads to a polymer with isotacticity of over 98% and high optical activity ([ ]D -536° (in CH2C12)) [33, 34]. The BINAPHOS catalyst described above is also effective in this type of copolymerization [25],... 

Fig. 6.23. Effect of thermal (a) and UV initiation (b), type of comonomer, and percentage of 1-dodecanol in the polymerization mixture on the mode pore diameter of quinidine-functionalized chiral monoliths. (Reprinted with permission from [56]. Copyright 2000 American Chemical Society). Reaction conditions polymerization mixture, chiral monomer 25 8 wt%, glycidyl methacrylate ( ) or 2-hydroxyethyl methacrylate ( ) 16 wt%, ethylene dimethacrylate 16 wt%, porogenic solvent 60 wt% (consisting of 1-dodecanol and cyclohexanol), polymerization time 20 h at 60°C (a) and 16 h at room temperature (b).

It has been reported that the effectiveness of copolymerized DOPO-type monomers can be further improved if the alcohol-amine derivatives of DOPO, for example, Structure 5.11, are used rather than similar structures not containing nitrogen.30 Of the FR fibers based on P-containing comonomers, it has been found that those based on Structure 5.10 are more hydrolytically stable, presumably because the P-containing group is in a cyclic structure and also should the hydrolysis of the P-0 bond occur, it will not lead automatically to a marked reduction in molecular weight.31 All the P-modified PETs appear to be subject to both the vapor-and condensed-phase mechanisms of flame retardance, with the former predominating.32 33... 

Musyanovych A, Rossmanith R, Tontsch C, Landfester K (2007) Effect of hydrophilic comonomer and surfactant type on the colloidal stability and size distribution of carboxyl-and amino-functionalized polystyrene particles prepared by miniemulsion polymerization. Langmuir 23(10) 5367-5376... 

Although the dynamic tests were restricted to the third generation grade, the micromechanisms of deformation appeared to show at least qualitative similarity with those observed for static loading in Igepal. Certainly, the effects of M, comonomer content and branch distribution have been shown elsewhere to be broadly similar in the two types of test. 

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