Locally Auxetic Behavior of Elastomeric Polypropylene on the 100 nm Length Scale

Franke, Mechthild; Magerle, R.

doi:10.1021/nn200957g

Cited by 15 publications

(19 citation statements)

References 50 publications

(89 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Particular processing steps are required for producing polymeric materials with an auxetic behavior, such as foams [62], microporous films and fibers [63,64], and macroscopically perforated sheets [65]. It was the first time that Franke et al observed an unexpected locally auxetic behavior took place in elastomeric polypropylene with a natural microstructure [66]. Upon uniaxial stretching, the angle between epitaxially grown lamella branches remained constant and the main lamellae were elongated, resulting in locally auxetic behavior on the 100-nm scale.…”

Section: Lamellae Evolution Of Bsk Ipp Upon Deformationmentioning

confidence: 99%

Insight into unique deformation behavior of oriented isotactic polypropylene with branched shish-kebabs

Chen

Fang

Hsiao

et al. 2015

Polymer

View full text Add to dashboard Cite

Section: Lamellae Evolution Of Bsk Ipp Upon Deformationmentioning

confidence: 99%

Insight into unique deformation behavior of oriented isotactic polypropylene with branched shish-kebabs

Chen

Fang

Hsiao

et al. 2015

Polymer

View full text Add to dashboard Cite

“…Cellulose (in both crystalline and amorphous phases) also enlarge in at least one direction at right-angles to the direction of strain (i.e auxetic or with negative Poisson's ratio) (Asamoah (2017), Yao et al (2012), Peura et al (2006), Nakamura et al (2004), and Franke and Magerle (2011)). Auxetics may be present with increased indentation resistance, increased shear stiffness, increased break resistance, increased acoustic response, negative linear compressibility, and negative thermal expansion in some cellulose functionalities.…”

Section: Expanded Backgroundmentioning

confidence: 99%

What Conformational Isomerism and Auxetics Typify Crystalline Cellulose?

Asamoah¹

2018

Preprint

View full text Add to dashboard Cite

SummaryAlmost all matter including viscoelastic cellulose respond to energy changes which almost invariably influence its atomic and molecular bond characteristics (length, orientation, and geometry). Changes in bond characteristics and quantised energy states/levels of conformationally isomeric cellulose is characterised by variations in the relative amounts of rotamers which has implications on the molecular organization and physical properties/integrity of cellulose that informs the processing and material application of cellulose. Cellulose is also reported to be auxetic. To fully establish how variations in the relative amounts of rotamers impact molecular organization and physical properties/integrity of cellulose and auxetics typical of crystalline cellulose as is usually found in non-native sources, a 1D bundle of cellulose microfibrils and 2D networks of cellulose mircofibrils were stretched in a Deben microtester, and their molecular straining followed with Raman spectroscopy. In generality, the amounts of rotamers was found to decrease with stress or strain, which influences the level of molecular order or disorder (degree of crystallinity), and in turn changes (inter-conversions) of cellulose conformations/allomorphs or even polymorphs. The auxetics of crystalline cellulose was also found to be around unity (-1.00). Expanded backgroundAlmost all matter respond to quantised energy changes as occurs in chemical reactions or physical loading, which almost invariably influence atomic and molecular organisation, bond characteristics (orientation and geometry) which in turn results in changes in energy states of matter. This change in atomic and or molecular bond characteristics is even more dramatic and crucial in in viscoelastic polymers (polymers with side chains). Cellulose as a plentiful, renewable, tuneable, affordable, non-toxic, semi-crystalline, lightweight, thermally stable, stiff and green viscoelastic polymer, exhibits conformational isomerism under quantised energy change (be it endothermic or exothermic) in which its isomers (low energy side chains) are found to solely rotate about at least one characteristic sigma bond as occurs in the CH2 (C-6) scissor mode of -CH2OH (hydroxymethyl/methylene bridge) functional group/moiety on (C-6) of cellulose (Jarvis; Agarwal and Ralph). Three kinds of rotamers, namely: gg (gauche-gauche), gt (trans-gauche) and tg (gauche-trans) characterize this scissor mode, and according to Argawal and Ralph (2014), the relative amounts of these three rotamers, are found to influence the intensity, shape and frequency of spectra located at 1460 cm -1 , 1470 cm -1 and 1480 cm -1 Raman bands corresponding to each kind of rotamer respectively. The relative amounts of the three ratamers varies within and between native (unprocessed) cellulose I and non-native (processed) cellulose I (i.e cellulose I, II, III, IV), with relative amounts of rotamers being significantly higher and more complex in native cellulose than non-native cellulose (Argawal and Ralph, 2014). Neverthele...

show abstract

“…These geometry-related questions are particularly relevant for auxetic materials (Greaves G. N. et al, 2011;Milton, 1992;Grima and E., 2000;Grima et al, 2005;Chetcuti et al, 2014;Bertoldi et al, 2010;Franke and Magerle, 2011;Dirrenberger et al, 2011). For these materials, characterised by negative values of the Poisson's ratio, the essential role of microstructural geometry has been recognised.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Geometry: The leading parameter for the Poisson’s ratio of bending-dominated cellular solids

Mitschke

Schury

Mecke

et al. 2016

International Journal of Solids and Structures

View full text Add to dashboard Cite

Locally Auxetic Behavior of Elastomeric Polypropylene on the 100 nm Length Scale

Cited by 15 publications

References 50 publications

Insight into unique deformation behavior of oriented isotactic polypropylene with branched shish-kebabs

Insight into unique deformation behavior of oriented isotactic polypropylene with branched shish-kebabs

What Conformational Isomerism and Auxetics Typify Crystalline Cellulose?

Geometry: The leading parameter for the Poisson’s ratio of bending-dominated cellular solids

Contact Info

Product

Resources

About