Structure-properties relationship in spun fibers of poly(ethylene terephthalate): Comparisons between samples obtained by terephthalic acid or dimethyl terephthalate processes

Russo, G.; Parravicini, Lidia; Auriemma, Finizia; Petraccone, Vittorio; Guerra, Gaetano; Bianchi, Rodrigo Fernando; Dino, Gabriele Di; Vitagliano, Vincenzo

doi:10.1002/(sici)1099-0488(19970430)35:6<889::aid-polb3>3.0.co;2-d

Cited by 5 publications

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“…A similar phenomenon has been observed for thermoplastic polymers, such as poly(ethyleneterephthalate) . In fact, poly(ethyleneterephthalate) fibers with higher content of diethylene glycol revealed a delayed crystallization, which allowed the progress of the amorphous phase orientation and, in turn, formation of oriented crystallites and development of higher tenacity.…”

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confidence: 62%

Crystallinity and crystalline phase orientation of poly(1,4-cis-isoprene) fromHevea brasiliensisandTaraxacum kok-saghyz

Musto

Barbera

Maggio

et al. 2016

Polym. Adv. Technol.

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Crystallization is studied for poly(isoprene-1,4-cis) from Hevea brasiliensis (natural rubber [NR]) and from taraxacum kok-saghyz, mainly by collecting wide-angle X-ray diffraction patterns after processing and stretching. Although rubber samples before stretching are generally fully amorphous, crystallization can be induced in NR samples by processing at room temperature under moderate pressure. This phenomenon is possibly associated with nucleation by saturated fatty acid components. For rubber samples being fully amorphous in the undeformed state, straininduced crystallization occurs only at high strain ratios (α > 4), leading to high degrees of crystalline phase orientation (f c > 0.9 for α = 5). Rubber samples presenting some crystallinity already in the unstretched state, on the contrary, reach much lower degrees of axial orientation, even for high strain ratios (f c < 0.7 for α = 5). These differences in crystallinity and in crystalline phase orientations produce large differences in stress-strain behavior of the rubber. By room temperature processing, the considered NR samples can also develop an unreported disordered crystalline modification, with low intensity of 120 and 121 reflections. This disordered crystalline modification, which is also maintained after axial stretching procedures, can rationalized by a structural disorder along the b axis, possibly associated with statistical sequences of A + TA À or A À T A + conformations for poly(isoprene-1,4-cis) chains. Copyright © 2016 John Wiley & Sons, Ltd.Keywords: poly(isoprene-1,4-cis); crystallinity; strain-induced crystallization INTRODUCTIONNatural rubber (NR) is the regular head-to-tail polymer essentially made by isoprene-1,4-cis units. [1][2][3][4] It is the most important rubber, with increasing worldwide consumption, that amounts at present to more than 12 million t/year.[5] At the origin of such a large commercial success are the NR outstanding properties: great strength [6,7] and tack [8][9][10] in the uncrosslinked state and in the crosslinked state, very high tensile strength [11,12] and crack growth resistance, both in static [13][14][15][16][17] and in fatigue [18][19][20][21][22][23][24] loading conditions. Beneficial for such NR properties is definitely the great mobility of the polymer chains that are usually amorphous at rest. However, also the ability of NR to crystallize plays a fundamental role. NR undergoes strain-induced crystallization (SIC) that is the rapid development of crystallization under straining. Many aspects of SIC have been reviewed, [25][26][27] and further works are continuously appearing, focused on the study of models, [28,29] crystallite structure, [30,31] segmental dynamics, [32] local strain response, [33] mechanism of deformation, [34] morphology, [35] orientation and deformation mechanisms, [36] crystallite melting temperature, [37] temperature dependence of the mechanical properties, [38] kinetics [36,39,40] and time [41] of crystallization, fatigue behavior, [42,43] effect of entanglements and endlinking n...

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