Formation of crazes in isotactic polypropylene and accompanying changes of energy

Yefimov, A.V.; Bulayev, V.M.; Ozerin, А. N.; Ребров, А. В.; Godovskii, Yu.K.; Bakeyev, N.F.

doi:10.1016/0032-3950(86)90417-x

Cited by 10 publications

(4 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The white spot represents the long and narrow craze, and the intensive scattering comes from the difference in electron density between the material inside the crazes oriented perpendicularly to the tensile direction and the polymer matrix. 36 Along the meridional direction, the weak and diffused blue signal is from the heating-induced initial voids. After hot stretching to 20% (in patterns c and d), the scattering pattern representing the craze turns to four leaf, which moves to near the beam stop and disappears during the following hot stretching.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The inner black spot represents the lamellae structure within the separated lamellae cluster, indicating that during cold stretching and heating, the lamellae structure is kept. The white spot represents the long and narrow craze, and the intensive scattering comes from the difference in electron density between the material inside the crazes oriented perpendicularly to the tensile direction and the polymer matrix . Along the meridional direction, the weak and diffused blue signal is from the heating-induced initial voids.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Stretching-Induced Uniform Micropores Formation: An in Situ SAXS/WAXS Study

Lei

Tian

et al. 2018

Macromolecules

View full text Add to dashboard Cite

Although the microporous membrane prepared based on the melt stretching mechanism has been commercialized for more than 20 years, the formation process from the initial lamellae structure to final fiber connecting bridges and pores is still unclear. In this work, to clarify the transformation mechanism, in situ SAXS and WAXS were carried out during hot stretching at 130 °C to 100%. The scattering patterns from the annealed film, cold stretched film to 20% (stretched at room temperature), and heating to 130 °C were also collected. The preparation technology was similar to that during the commercial fabrication. It was found that during cold stretching to 20% many long and narrow crazes are formed between separated lamellae clusters, and a part of destroyed crystals appeared. After heating to 130 °C, oriented structure and needlelike voids appeared, which was related to the shrinkage of oriented amorphous chains along the transverse direction, due to the tension stress effect. Also some oriented crystal structure was formed. During hot stretching to 20%, the lamellae which are close to the craze wall are rotated as the fibril crystal as the axle and the connecting bridges were formed among the separated lamellae cluster. Further stretching to 100%, these connecting bridges transformed to fiber bridges, contributed by strain-induced crystallization. During the whole hot stretching, the amorphous chains oriented along the machine direction and also crystallized into fiber bridges. This is the first time to clearly describe the lamellae to fiber bridges transformation during the preparation of microporous membrane.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Stretching-Induced Uniform Micropores Formation: An in Situ SAXS/WAXS Study

Lei

Tian

et al. 2018

Macromolecules

View full text Add to dashboard Cite

show abstract

“…Let us first consider the structure of the HEPP precursors as substrates for the impregnation and sensor fabrication. These precursors were produced by stretching in air, which produces necking, followed by annealing in the free-standing state at 160 °C for 30 min . Upon such annealing, the samples shrunk, reducing their dimensions along the length by about 52–55%.…”

Section: Results and Discussionmentioning

confidence: 99%

“…HEPP precursors/substrates in the form of a 105 μm thick tape were produced from a conventional blown PP film (Tver Khimvolokno, Russia; thickness 200 μm; M w = 3 × 10 5 ) as follows: 2 cm wide pieces of PP film tape were uniaxially stretched in air at room temperature by 500% with respect to their original length. The necked part of the resulting tape was then cut out, placed in a dry oven, and allowed to relax in a free state at 160 °C for 30 min (annealing). During such thermal treatment, the stretched tape shrunk by ∼52–55% and converted into HEPP.…”

Section: Methodsmentioning

confidence: 99%

Phosphorescent Oxygen and Mechanosensitive Nanostructured Materials Based on Hard Elastic Polypropylene Films

Okkelman

Долгова

Banerjee

et al. 2017

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

It is well known that sensitivity of quenched-phosphorescence O sensors can be tuned by changing the nature of indicator dye and host polymer acting as encapsulation and quenching mediums. Here, we describe a new type of sensor materials based on nanostructured hard elastic polymeric substrates. With the example of hard elastic polypropylene films impregnated with Pt-benzoporphyrin dye, we show that such substrates enable simple one-step fabrication of O sensors by standard and scalable polymer processing technologies. In addition, the resulting sensor materials show prominent response to tensile drawing via changes in phosphorescence intensity and lifetime and O quenching constant, K. The mechanosensitive response shows reversibility and hysteresis, which are related to macroscopic changes in the nanoporous structure of the polymer. Such multifunctional materials can find use as mechanically tunable O sensors, as well as strain/deformation sensors operating in a phosphorescence-lifetime-based detection mode.

show abstract

Origin of High Elastic Recovery of Hard-elastic Polypropylene Film at Room Temperature: the Mixed Contribution of Energy Elasticity and Entropy Elasticity

Xie

Lei

2020

Chin J Polym Sci

View full text Add to dashboard Cite

Formation of crazes in isotactic polypropylene and accompanying changes of energy

Cited by 10 publications

References 3 publications

Stretching-Induced Uniform Micropores Formation: An in Situ SAXS/WAXS Study

Stretching-Induced Uniform Micropores Formation: An in Situ SAXS/WAXS Study

Phosphorescent Oxygen and Mechanosensitive Nanostructured Materials Based on Hard Elastic Polypropylene Films

Origin of High Elastic Recovery of Hard-elastic Polypropylene Film at Room Temperature: the Mixed Contribution of Energy Elasticity and Entropy Elasticity

Contact Info

Product

Resources

About