Polybutene-1 crystals

Isotactic polybutene crystallizes into three different forms. When it cools from the melt, it initially crystallizes into a metastable crystalline one. After several days, however, it transforms into a different form. Noticeable changes in melting point, density, flexural modulus, yield, and hardness accompany this transformation. The third crystalline form is due to crystallization from solution. The polymer exhibits good impact and tear resistance. It is also resistant to environmental stresscracking. 

Monasse B, Haudin JM. Morphologies and regimes of growth of polybutene crystals in phase-II. Makromol Chem Makromol Symp 1988 20/21 295. 

Kinetics of Crystallization of Polypropylene Fractions and Polybutene-1-Part I", ONR Tech Rept 43, Contract Nonr 3357(00), Univ of Mass, Amherst (1962) 4) A. Opschoor,... 

In the crystal state most stereoregular polymers have helical conformations. Group s(M/N) 1 comprises all the isotactic vinyl polymers [polypropylene, polybutene, polystyrene, etc., M/N = 3/1 poly-o-methylstyrene, etc., 4/1 ... 

Cocrystallization in copolymers of a-olefins. II — Butene-1 copolymers and polybutene type II—I crystal phase transition. Polymer 7, 23 (1965). 

Significantly different seemed intiaUy the crystal morphology of polyethylene, polybutene-1, polypropylene, polystyrene, poly(4-methyl pen-tene-1), and polyisoprene polymerized with varying solvents and at varying temperatures (114, 123). Discrete hollow particles with a fibrous texture could be observed. The fibrils had an appearance similar to polyethylene crystallized from solution sheared by rapid stirring (118). A closer analysis of this similarity was carried out by Wikjord and Manley (124), Keller and Willmouth (117), and Ingram and Schindler (125) for polyethylene. 

A few examples of 1-butene co-polymers with higher a-olefins have been reported. Addition of 1-hexene stabilizes form II of polybutene and is included in the crystals.315 C4/C6 random co-polymers are soft or semirigid resins with characteristics that markedly differ from those of, for example, G4IC2 random co-polymers.908... 

Fig. 6 Needle crystal morphology of polybutene-1. (From Refl l)...

A new high impact blend of PET and polybutene (Valox CT) is also available. - The melt viscosity of blends of PET and nylon-66 has been reduced by the addition of polyvinyl alcohol. Self reinforcing PET has been produced by the addition of p-hydroxybenzoic acid which forms liquid crystals in the composite. 

Some of fhe Cryo-TEM and Cryo-HRTEM applications in polymer materials are (i) studies of crystal transformation, for example, the nucleation process and shape of crystals in lamellar crystals of polybutene-1 [74] (ii) studies of the morphology of several materials, such as polypeptides... 

Ultravis 2000. See Polybutene Ultrawet 40SX. See Sodium xylenesulfonate Ultrax . See Liquid crystal polymer UltraYellow YV1988] UltraYellow YV2288. See Ferric oxide... 

It is sometimes observed that the helix which is in equilibrium at a high temperature transforms to another helix at a lower temperature. FIFE, on heating from below to above 1(TC, transforms from a 13/1 to a 15/1 helix. The transformation yields an abrupt change in crystal volume of the order of 1%. This appredable change in volume at about room temperature presents important, sometimes unfortunate, consequences for the dimensions of precisely machined parts. Another example of a helix transformation occurs in polybutene (2.N.3),... 

The excellent electrical insulation property of E-glass has found many applications in this field. Fabrics made of textile glass yarn is the backbone of the printed circuit board of the modern electronic industry. Polybutene terephthalate, polyphenylene sulfide, and liquid crystal polymer reinforced with chopped glass fiber are also widely molded into electronic components (23). 

Figure 6.7 Enantiomorphous mode of packing polybutene-1 chains in a crystal (21).

Finally, a few comments about the uniqueness of polymer crystal structures and phase space localization are warranted. Almost all crystallizable polymers exhibit polymorphism, the ability to form different crystal structures as a result of changes in thermodynamic conditions (e.g., temperature or pressure) or process history (e.g., crystallization conditions) [12]. Two or more polymorphs of a given polymer result when their crystal structures are nearly iso-energetic, such that small changes in thermodynamic conditions or kinetic factors cause one or another, or both, to form. Polymorphism may arise as a result of competitive conformations of the chain, as in the case of syndiotactic polystyrene, or as a result of competitive packing modes of molecules with similar conformations, as in the case of isotactic polypropylene. In some instances, the conformational change may be quite subtle isotactic polybutene, for example, exhibits... 

Fig. 16-12. Storage and loss moduli in extension at 100 Hz, plotted with logarithmic scale against temperature for isotactic polystyrene (PS), isotactic polypropylene (PP), and isotactic polybutene-1 (PB-1), crystallized from the melt. Degrees of crystsdlinity estimated as 43%, 65%, and 45% respectively. (Takayanagi. )...

Polybutene-based hot-melt adhesives are tough, partially crystalline, and their slow crystallization rates lead to long open times. Copolymers of butene result in softer and more flexible adhesives. In general, polybutene and its copolymers have low temperatures for recrystallization from the melt. This permits stress release in the adhesive bond, which may have been applied to cold surfaces. Polybutene and its olefinic copolymers exhibit good bonding to nonpolar surfaces but poor compatibility with polar substances. These hot-melt adhesives have been used on rubbery substrates and are available as pressure-sensitive adhesives. 

PB base polymers are semicrystalUne isotactic thermoplastic polyolefins. They are derived from the polymerization of butene-1 monomer with or without other alpha-olefin monomers utilizing a Ziegler-Natta type of catalyst. Their unique crystallization behavior means longer open times of adhesive and sealant formulations compared to other commonly used polymers such as polyethylene and ethylene-vinyl acetate copolymer (EVA). Polybutylene (PB), also called polybutene-1 or poly-1-butene, is different from polybutene or polyisobutylene (PIB). PIB is amorphous and rubbery, and comes in the form of a viscous liquid or big, hard block (6 in. in length and width or could be larger). PB base polymers are sup-pUed in the form of small pellets (about 0.25 in. in diameter) or nibs. 

Both isotactic poly(propylene-co-butene) [81, 82] and syndiotactic poly(propylene-co-butene) [83] statistical copolymers exhibit isodimorphic behavior when crystallized. In isotactic poly(propylene-co-butene), the copolymer was found to crystallize over the entire range of butene content. A transition in crystal unit cell structure was observed at about 50 mol% butene, where below this composition, the crystalline phase resembled that for polypropylene and above this composition, the copolymer was essentially polybutene with propylene defect units [81]. The observed isodimorphic behavior can be explained by the similar helical chain structures exhibited by both polypropylene and polybutene in the crystal, which results in a relatively small free energy penalty for co-crystallization [42, 81-83],... 

PVF2), polypivalolactone (PPVL), polypropylene (PP), polybutene (PB), and PET. In all cases (except PET) the ultraquenched samples have shown an extra peak in the dynamic mechanical spectra, below the normal Tg peak. These polymers can be divided into two classes, those which crystallize at the new, lower peak and those which crystallize at tlw higher, normal Tg. For convenience we will label these two peaks and T, Representative results are considered below, considering first those which crystallize at the new, low dynamical mechanical spectrum peak. For some of the samples (PP, PVF2, and PB) ca. 0.2 mm thick samples were used for the dynamic mechanical and DSC studies. 

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