Craze behaviour in isotactic polystyrene: 1. Craze-spherulite interaction

Morel, Donald E.; Grubb, D. T.

doi:10.1016/0032-3861(84)90298-2

Cited by 33 publications

(8 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To obtain a true spherulitic structure, the films were heated to 250°C under nitrogen, after which they were bonded to the grids and heat treated as previously. Spherulites were clearly visible after a few minutes at 18O"C, growing at approximately 0.15 pm/min, consistent with iPS spherulite growth rate data given elsewhere (14,(28)(29)(30)(31).…”

Section: Methodssupporting

confidence: 89%

“…A cluster model has been adopted to describe the resulting lamellar structure; a given chain is considered to be divided into sub-lengths, each consisting of three adjacent reentrant chain folds incorporated in a lamella, and a similar length of amorphous material (ips spherulites are approximately 50% crystalline). It has been pointed out that for the observed lamellar thicknesses in ips, such a unit has a molecular weight approximately equal to Me (14). Thus, crystallization may be consistent both with the idea of a fured entanglement network and with the rejection of entanglements into the amorphous interlamellar regions, often implicit in models for lamellar folding.…”

Section: Flg 2 Plot Of the Estimated Entanglement Density V Againstsupporting

confidence: 52%

“…cated random crystallite orientation in such films]. The irregularity of the craze bulk interface is believed to be a consequence of the uneven thickness, and of local variations in the craze extension ratio, A, , , , , associated with variations in the local lamellar orientation (14). Also, as shown in Fig.…”

Section: Results and Discussion Deformation In Ipsmentioning

confidence: 98%

“…In the spherulitic films, the morphology was that of a central sheaf containing in-plane c-axis orientation. surrounded by plates of vertical c-axis orientation as described elsewhere for iPS (14,30). In the particular example shown in Fig.…”

Section: Results and Discussion Deformation In Ipsmentioning

confidence: 99%

See 3 more Smart Citations

Deformation and entanglement in semicrystalline polymers

Plummer

Cudré‐Mauroux²,

Kausch

1994

Polymer Engineering & Sci

View full text Add to dashboard Cite

Transmission electron microscopy and optical studies of thin films of isotactic polystyrene (iPS) and polyoxymethylene (POM) provide evidence for a distinction between crazing mechanisms in semicrystalline polymers above and below Tg. In the latter temperature regime, deformation in iPS and POM crystallized at high supercooling has been discussed in terms of existing models for crazing in amorphous glassy polymers, based on entanglement ideas. Above Tg, where the difference in mechanical behavior of the amorphous and crystalline regions becomes marked, the fibrillar nature of local deformation appears to be a consequence of the inhomogeneity of the undeformed polymer.

show abstract

Section: Methodssupporting

confidence: 89%

Section: Flg 2 Plot Of the Estimated Entanglement Density V Againstsupporting

confidence: 52%

Section: Results and Discussion Deformation In Ipsmentioning

confidence: 98%

Section: Results and Discussion Deformation In Ipsmentioning

confidence: 99%

See 2 more Smart Citations

Deformation and entanglement in semicrystalline polymers

Plummer

Cudré‐Mauroux²,

Kausch

1994

Polymer Engineering & Sci

View full text Add to dashboard Cite

show abstract

“…Crystalline domains in semicrystalline polymers have been shown to impact the development of crazes, , alter the competition between crazing and shear yielding, , and disrupt stress distribution within a plastic. ,, Increasing crystallinity also has been reported to slow the rate of physical aging. , However, there are no systematic studies that focus on these physical phenomena in the presence of diblock copolymer particles.…”

Section: Introductionmentioning

confidence: 99%

Crazing and Toughness in Diblock Copolymer-Modified Semicrystalline Poly(l-lactide)

et al. 2021

View full text Add to dashboard Cite

Sustainable semicrystalline poly(l-lactide) (PLLA) was melt mixed with 5 wt % poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) diblock copolymer, resulting in blends that display an exceptional combination of properties. The blends were annealed at various temperatures, leading to different degrees of crystallinity. The addition of 5 wt % PEO-PBO produced finely dispersed liquid particles that caused a significant reduction in the time for crystallization after quenching from the melt, where T m = 166 °C. At 95 °C, the halftime for crystallization was t 1/2(95 °C) = t 1/2 o/7, while at 135 °C, t 1/2(135 °C) = t 1/2 o/5, where t 1/2 o is the time required to obtain 50% of the final extent of crystallization with pure PLLA. The block copolymer particles also enhanced the ductility of the blends by facilitating stress-induced cavitation and uniform crazing without impacting the modulus. Tensile toughness increased by 7–15 fold, scaling inversely with the degree of crystallinity. The deformation mechanism was investigated by small- and wide-angle X-ray scattering as a function of applied strain, revealing that the craze volume is dependent on crystallinity, while the crystal structure displayed minimal changes. Regardless of the extent of crystallinity, crazing was found to be the primary deformation mechanism, countering the ductile-to-brittle transition associated with the aging of PLLA. Adding 5 wt % PEO-PBO extends the strain at break from 4% for pure PLLA after 2 days to more than approximately 50% after 85 or more days of aging. These findings, along with the industrially relevant blend preparation method, reveal that PEO-PBO is a unique and potent additive that could expand the applications served by PLLA, promoting a more sustainable future.

show abstract

Polymer Blends

Keskkula

Paul

Barlow

2000

Kirk-Othmer Encyclopedia of Chemical Technology

View full text Add to dashboard Cite

The physical approach of blending polymers to develop new or improved polymeric products has been an extremely active area of academic and industrial research for nearly three decades, owing to the much higher costs associated with the alternative of chemical synthesis of new polymers. This activity has been paced by the rapid commercialization of products based on blend technology, including polyamide‐, polyester‐, styrenic‐, vinyl‐, acrylic‐, olefinic‐, and epoxy‐ based materials. The basic principles needed to practice this approach are reviewed, including molecular and thermodynamic factors affecting blend‐phase behavior (miscibility or compatibility), phase morphology, processing, interfacial behavior, and chemical reactions that can occur. General trends and examples of physical properties are given, with special emphasis on the important commercial developments, followed by speculations about future developments.

show abstract

Craze behaviour in isotactic polystyrene: 1. Craze-spherulite interaction

Cited by 33 publications

References 36 publications

Deformation and entanglement in semicrystalline polymers

Deformation and entanglement in semicrystalline polymers

Crazing and Toughness in Diblock Copolymer-Modified Semicrystalline Poly(l-lactide)

Polymer Blends

Contact Info

Product

Resources

About