Study of dispersion morphologies of isotactic polypropylene and linear low density polyethylene blends by scanning electron microscopy

Liu, Yan; Truss, R. W.

doi:10.1002/(sici)1097-4628(19960531)60:9<1461::aid-app21>3.0.co;2-3

Cited by 12 publications

(2 citation statements)

References 2 publications

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“…Although there are many published studies that have examined the miscibility and compatibility of conventional PE in PP,4–27 few have investigated PE copolymers prepared from metallocene catalysts 28, 29. In previous works, the mechanical properties and crystallization behavior of three blends prepared from a metallocene linear low‐density polyethylene (m‐LLDPE) and a PP random copolymer were reported.…”

Section: Introductionmentioning

confidence: 99%

Low‐Glutamine Fed‐Batch Cultures of 293‐HEK Serum‐Free Suspension Cells for Adenovirus Production

Lee

Yap

et al. 2003

Biotechnology Progress

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Recent developments in gene therapy using adenoviral (Ad) vectors have fueled renewed interest in the 293 human embryonic kidney cell line traditionally used to produce these vectors. Low-glutamine fed-batch cultures of serum-free, suspension cells in a 5-L bioreactor were conducted. Our aim was to tighten the control on glutamine metabolism and hence reduce ammonia and lactate accumulation. Online direct measurement of glutamine was effected via a continuous cell-exclusion system that allows for aseptic, cell-free sampling of the culture broth. A feedback control algorithm was used to maintain the glutamine concentration at a level as low as 0.1 mM with a concentrated glucose-free feed medium. This was tested in two media: a commercial formulation (SFM II) and a chemically defined DMEM/F12 formulation. The fed-batch and batch cultures were started at the same glucose concentration, and it was not controlled at any point in the fed-batch cultures. In all cases, fed-batch cultures with double the cell density and extended viable culture time compared to the batch cultures were achieved. An infection study on the high density fed-batch culture using adenovirus-green fluorescent protein (Ad-GFP) construct was also done to ascertain the production capacity of the culture. Virus titers from the infected fed-batch culture showed that there is an approximately 10-fold improvement over a batch infection culture. The results have shown that the control of glutamine at low levels in cultures is sufficient to yield significant improvements in both cell densities and viral production. The applicability of this fed-batch system to cultures in different media and also infected cultures suggests its potential for application to generic mammalian cell cultures.

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Section: Introductionmentioning

confidence: 99%

Low‐Glutamine Fed‐Batch Cultures of 293‐HEK Serum‐Free Suspension Cells for Adenovirus Production

Lee

Yap

et al. 2003

Biotechnology Progress

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show abstract

Section: Introductionmentioning

confidence: 99%

Evaluation of the crystallization kinetics and melting of polypropylene and metallocene‐prepared polyethylene blends

Razavi‐Nouri

Hay

2007

J of Applied Polymer Sci

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The kinetics of the isothermal crystallization of a polypropylene (PP) random copolymer containing 5 mol % ethylene, a metallocene linear low-density polyethylene (m-LLDPE) with 3.3 mol % hexene-1 as a comonomer, and three blends were studied with differential scanning calorimetry at temperatures sufficiently high to prevent any crystallization of m-LLDPE. The analysis was carried out with the Avrami equation. The overall crystallization rate and the equilibrium melting temperature of the PP copolymer decreased with increasing amounts of m-LLDPE in the blends. The former was attributed to the effect of m-LLDPE in reducing the number of primary nuclei, and the latter was attributed to a lowering of the fold surface energy due to the limited partial miscibility of the blend components.

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Influence of phase structure on impact toughening of isotactic polypropylene by metallocene-catalyzed linear low-density polyethylene

Kukaleva

Jollands

Cser

et al. 2000

J. Appl. Polym. Sci.

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ABSTRACT:In the present study isotactic polypropylene (PP) and metallocene-catalyzed linear low-density polyethylene (mLLDPE) were blended together to obtain thermoplastic materials (compositions) with improved toughness. Structure-property relationships were determined for these compositions with the help of scanning electron microscopy (SEM). Special emphasis was made on tracing the morphological features that led to the optimum mechanical performance. A co-continuous type of structure was found to have much superior toughness as compared to a dispersed-matrix structural type, for blends comprised of the same components (PP and mLLDPE). The study showed the fascinating possibility of creating toughened PP blends by inducing a co-continuous structure.

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Study of dispersion morphologies of isotactic polypropylene and linear low density polyethylene blends by scanning electron microscopy

Cited by 12 publications

References 2 publications

Low‐Glutamine Fed‐Batch Cultures of 293‐HEK Serum‐Free Suspension Cells for Adenovirus Production

Low‐Glutamine Fed‐Batch Cultures of 293‐HEK Serum‐Free Suspension Cells for Adenovirus Production

Evaluation of the crystallization kinetics and melting of polypropylene and metallocene‐prepared polyethylene blends

Influence of phase structure on impact toughening of isotactic polypropylene by metallocene-catalyzed linear low-density polyethylene

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