A Morphological Study of Linear and Branched Poly(Ethylene Terephthalate) using Transmission Electron Microscopy and Small‐Angle X‐Ray Scattering

Sutton, David; Wanrooij, P.; Hanley, Tracey; Burford, R. P.; Heeley, Ellen L.; Knott, Robert

doi:10.1080/00222340500323623

Cited by 3 publications

(3 citation statements)

References 39 publications

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“…The 1D correlation function Γ 1 was then calculated: where x is the real‐space dimension and Q is the invariant given by From the 1D correlation function analysis, the long period spacing ( L p ), the average hard and soft block spacings ( L 1 and L 2 ), and overall degree of local crystallinity ( L p / L 1 ) can be obtained. Distinguishing between L 1 and L 2 dimensions is not possible by SAXS alone and the application of a second technique, such as transmission electron microscopy, is therefore required 15, 27, 28…”

Section: Methodsmentioning

confidence: 99%

Crystallisation kinetics of novel branched poly(ethylene terephthalate): a small‐angle X‐ray scattering study

Hanley

Forsythe

Sutton

et al. 2006

Polymer International

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Three types of poly(ethylene terephthalate) (PET) were investigated: linear (unprocessed) bottle‐grade PET (intrinsic viscosity, IV ∼ 0.82 dL g−1); a branched PET produced from linear PET by reactive extrusion with 0.4% w/w pyromellitic dianhydride and pentaerythritol in 5:1 molar ratio (IV ∼ 0.97 dL g−1); and a control sample produced from the same linear PET by extrusion under the same conditions without the reactive agents (IV ∼ 0.71 dL g−1). A key finding is that the reactive extrusion process, presumably as a consequence of branching and branch distribution, significantly modifies the crystallisation kinetics and changes the final morphology. Using small‐angle X‐ray scattering (SAXS) and differential scanning calorimetry (DSC), the crystallisation kinetics of PET was monitored from the melt (270 °C) to a crystallisation temperature of either 205 or 210 °C. The IV of the branched PET was ∼ 21% greater than that of the unprocessed PET, and the rate of melt crystallisation (from DSC measurements) was 510 s for the branched, 528 s for the control, and 640 s for the unprocessed PET. The lamellae spacings measured from the equilibrium SAXS patterns were ∼160 ± 10 Å for the branched PET and ∼180 ± 10 Å for the unprocessed PET. Such properties offer the potential for new applications requiring high‐melt‐strength PET. Copyright © 2006 Society of Chemical Industry

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Section: Methodsmentioning

confidence: 99%

Crystallisation kinetics of novel branched poly(ethylene terephthalate): a small‐angle X‐ray scattering study

Hanley

Forsythe

Sutton

et al. 2006

Polymer International

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“…Even given the extensive prior knowledge of the PET molecular structure, it is always advisable to use multiple experimental techniques when samples are investigated, particularly those prepared with a complex industrial process. In the past, we have used transmission electron microscopy;23 however, we considered it inappropriate for this study because of the complex sample preparation (e.g., thin samples and staining) and the very small area scanned per image. Optical microscopy was considered more appropriate, having sufficient spatial resolution to provide supporting evidence for the molecular morphology distribution derived from the SAXS patterns.…”

Section: Introductionmentioning

confidence: 99%

Effects of selected process parameters on the morphology of poly(ethylene terephthalate) preforms and bottles

Hanley

Sutton

Karatchevtseva

et al. 2007

J of Applied Polymer Sci

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Small-angle X-ray scattering (SAXS) studies and polarized optical microscopy were undertaken to explore possible morphological explanations for the poor mechanical strength in the petaloid bases of poly(ethylene terephthalate) bottles. With a standard commercial production line, one set of injection-molded preforms was overpacked by 1.1 wt % to investigate the effect on the molecular morphology with respect to a set of control samples. Both sets of preforms showed highly crystalline and oriented areas corresponding to the injection gate region. The main body of the control preform was amorphous, and although the overpacked preform was essentially amorphous, there was some evidence for weak crystallinity. The SAXS patterns of the bottle petaloid base blown from the corresponding preforms produced similar SAXS patterns for overpacked and control bottle bases, indicating that the commercial process is robust at least to this degree of overpacking. Optical microscopy showed detailed crystalline features around the gate region and thin crystalline layers sandwiched between a quenched skin layer in direct contact with the cold mold walls and the main flow of material into the mold.

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“…SAXS investigations of PET crystallization have been the subject of many previous studies (Haubruge et al, 2004(Haubruge et al, , 2003Xia et al, 2001;Ivanov et al, 2001;Wang et al, 1999;Rule et al, 1995;Lee et al, 2003;Mahendrasingam et al, 2003;Sutton et al, 2005); however, none to date have focused on branched PET, apart from our own quiescent studies (Hanley et al, 2006). In an attempt to more closely approximate commercial processing conditions, several research groups are currently conducting real-time SAXS experiments to study shearinduced crystallization, especially in thermoplastics (Heeley et al, 2003;Koscher & Fulchiron, 2002;Agarwal et al, 2003;Stribeck et al, 2004;Somani et al, 2000;Kornfield et al, 2002;Kumaraswamy et al, 2004;Duplay et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

A small-angle X-ray scattering study of the effect of chain architecture on the shear-induced crystallization of branched and linear poly(ethylene terephthalate)

et al. 2007

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A small-angle X-ray scattering study of the effect of chain architecture on the shear-induced crystallization of branched and linear poly ( The synchrotron-based small-angle X-ray scattering (SAXS) technique was used to investigate the shear-induced crystallization kinetics of branched/unbranched poly(ethylene terephthalate) (PET). Reactive extrusion of bottle-grade PET with the branching and chain-extension agents pyromellitic dianhydride and pentaerythritol results in enhanced rheological properties, such as higher melt strength and higher viscosity. In this study, six samples of PET were investigated: linear PET [intrinsic viscosity (IV) ' 0.76 dm 3 g À1 ]; four branched PETs produced from linear PET by a reactive extrusion technique (IV ' 0.86-1.06 dm 3 g À1 ); and a control PET (IV ' 0.73 dm 3 g À1 ) extruded under the same conditions without reactive agents. SAXS data were recorded for the PET at the melt temperature and time-resolved SAXS data were recorded following the application of a step shear (53 s À1 for 2 s). As the PET IV was increased, the extent of shear-induced orientation increased, whilst the time taken for the polymer to initiate and complete crystallization decreased. IntroductionThe majority of commercial polymer processing involves the application of shear stresses to molten polymers. To analyse the effects of polymer architecture combined with shear stress, a study was undertaken on the crystallization kinetics of a series of different grades of poly(ethylene terephthalate) (PET) prepared using a novel reactive extrusion process (Van Diepen et al., 1998). Reactive extrusion of bottle-grade PET with the branching and chain-extension agents pyromellitic dianhydride (PMDA) and pentaerythritol (penta) resulted in enhanced rheological properties, such as higher melt strength and higher viscosity (Van Diepen et al., 1998;Forsythe et al., 2006).A key finding of a previous isothermal crystallization study of these novel PETs under quiescent conditions (zero shear) (Hanley et al., 2006) was that the reactive extrusion process significantly modified the crystallization kinetics and changed the final polymer morphology. In summary, the rate of melt crystallization of the branched PET was reduced by up to~20% and the lamella spacing reduced by~10%. In particular it was found that varying the relative amounts of PMDA and penta gave significantly higher melt strengths and viscosities compared to the addition of PMDA alone. The improvements as a result of co-addition included lower extruder torque values, die pressures and melt temperatures, and consequently lower levels of degradation. The additives worked in two ways: (i) the alcoholysis of the PET by the added penta produced a branched PET; and (ii) the PMDA caused chain extension and repair of the chain scissions that occur during alcoholysis. The resulting PET was investigated by a combination of rheology, end-group analyses and gel permeation chromatography (GPC) and was found to be a hyperbranched polyester with long-chain branching . The exten...

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A Morphological Study of Linear and Branched Poly(Ethylene Terephthalate) using Transmission Electron Microscopy and Small‐Angle X‐Ray Scattering

Cited by 3 publications

References 39 publications

Crystallisation kinetics of novel branched poly(ethylene terephthalate): a small‐angle X‐ray scattering study

Crystallisation kinetics of novel branched poly(ethylene terephthalate): a small‐angle X‐ray scattering study

Effects of selected process parameters on the morphology of poly(ethylene terephthalate) preforms and bottles

A small-angle X-ray scattering study of the effect of chain architecture on the shear-induced crystallization of branched and linear poly(ethylene terephthalate)

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