Influence of Melt-Draw Ratio on the Crystalline Structure and Properties of Polypropylene Cast Film and Stretched Microporous Membrane

Xu, Ruijie; Chen, Xiande; Xie, Jianhe; Cai, Quan; Lei, Caihong

doi:10.1021/acs.iecr.5b00215

Cited by 34 publications

(44 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We emphasize the importance of cavitation triggered at large strain as it can be regarded as a signal to predict the ultimate life of the materials upon stretching. Meanwhile, the appearance of voids sometimes is needed in some special fields, for example, creating microporous separation membranes . Understanding the evolution of cavities during the deformation process can provide the possibility of finding an efficient way to promote, restrain, or even heal the cavities.…”

Section: Introductionmentioning

confidence: 99%

Cavitation‐Induced Stress Whitening in Semi‐Crystalline Polymers

Men

2018

Macro Materials & Eng

View full text Add to dashboard Cite

Cavitation‐induced stress whitening in semi‐crystalline polymers during stretching significantly influences the physical properties of the materials. This review summarizes studies focusing on two different cavitation processes triggered at small and large strain regimes. The corresponding mechanisms of these two cavitation processes are discussed. For cavitation activated at small strain, there are two basic but distinctly different models with the initiation of cavities either in the amorphous phase or in the crystalline skeleton. For the cavitation triggered at a large strain regime, there are also two different arguments being either due to the defects located in the ends of micro‐fibrils or as a consequence of the fragmentation of load‐bearing inter‐fibril/micro‐fibril tie chains in highly oriented amorphous networks. A unified understanding of the cavitation processes during stretching semi‐crystalline polymers based on interpenetrated network model is proposed. Finally, this review outlooks future research topics for better understanding the cavitation mechanism to meet the industrial need.

show abstract

Section: Introductionmentioning

confidence: 99%

Cavitation‐Induced Stress Whitening in Semi‐Crystalline Polymers

Men

2018

Macro Materials & Eng

View full text Add to dashboard Cite

show abstract

“…2. 22,23,34 To better characterize the crystalline morphology under different DR values, the etched surface morphology of SEM photographs is presented in Fig. According to Daniel 32 and Tao, 33 the most stable TPX crystalline structure of form I could be obtained through cooling from the molten state and is evidenced by the reections at 2q ¼ 9.5 , 13.4 , 16.6 , 18.5 , 20.6 and 21.5 , which belong to peaks not being presented in our results.…”

Section: Resultsmentioning

confidence: 99%

“…14,20 Some papers [21][22][23] reveal that the elongation induced morphology is strongly dependent on the effective stretching ow expressed in terms of the melt draw ratio. A precursor lm with a lamellar morphology is believed to be obtained by crystallization of the chains during melt stretching, which in the literature is called stress induced crystallization.…”

Section: Introductionmentioning

confidence: 99%

Influences of melt-draw ratio and annealing on the crystalline structure and orientation of poly(4-methyl-1-pentene) casting films

Yin

et al. 2016

RSC Adv.

View full text Add to dashboard Cite

Poly(4-methyl-1-pentene) casting films with row-nucleated lamellar structure were extruded through a slit die followed by stretching using a chill roll. The influences of melt draw ratio, annealing temperature, annealing time and supplied strain level on the crystalline morphology and orientation of the poly(4-methyl-1-pentene) casting films were carefully investigated by means of scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectrometry and X-ray diffraction. It was found that the crystalline morphology and the degree of orientation were greatly influenced by the melt draw ratio. In addition, both the changes of crystallinity and orientation degree exhibited similar tendencies (firstly increasing and then decreasing) upon increasing the free annealing temperature and time. The use of an appropriate temperature and time meant that molecular chains of the amorphous region could rearrange into a crystal lattice and defects could be removed, while an excessive annealing temperature and time could lead to partial imperfect crystals melting and recrystallizing or even disorientation phenomena. In contrast to the free annealing method, it was surprisingly discovered that annealing under supplied strain was really helpful in improving the crystalline structure and orientation of casting films.

show abstract

“…[1][2][3]9,12,13 Some polyolefin membranes have been commercially produced by stretching process, but only patents were filed without any detailed description of the of the fabrication procedure. 2,9,[17][18][19][20][21][22] Subsequently, precursor films go through an annealing process to improve the perfection of crystalline structure in the crystalline region. Many studies have indicated that the polymer molecular structure, i.e., molecular weight (M w ) and molecular weight distribution (MWD), and also processing variables are main factors for this method in controlling the properties of the precursor film and, consequently, the properties of the porous membrane.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3]9 It has been reported that annealing changes the nano-scale structure of the precursor films, especially the crystalline structure and enhances the physical properties of semicrystalline polymers by contributing to chain rearrangement. [2][3][4]9,18,19,[22][23][24]27,28 However, a few studies have been reported concerning the formation of microporous membranes from high density polyethylene (HDPE) by dry-stretching. 3,[23][24][25][26] On the other hand, many works focused on the relationship between stretching conditions and properties of finally microporous membranes.…”

Section: Introductionmentioning

confidence: 99%

Influence of precursor film microstructure on properties of HDPE microporous membranes prepared by stretching

Yadegari

Morshedian

Khonakdar

et al. 2017

J of Applied Polymer Sci

View full text Add to dashboard Cite

Oriented HDPE films having a stacked lamellar morphology were prepared to develop microporous membranes through cast film extrusion followed by stretching. Applying higher draw ratios (DR) and annealing the cast films improved crystal alignments remarkably. It was shown the improvement in c-axis orientation upon annealing was more significant for the films prepared with lower DR. Furthermore, applying Raman spectroscopy, the amorphous mass fraction of the films was obtained. Subsequently, considering a three-phase structure (i.e., crystal, amorphous and interphase), the interphase content of the films was also determined. A distinct DR dependence of the interphase content was noticed. It was observed that in addition to crystal perfection upon annealing, the amorphous phase fraction was also decreased due to possibly increase in free volume, promoting lamellar separation and cavitation during the subsequent stretching step. SEM images of the membranes surfaces as well as their normalized water vapor transmission rate (WVTR) values indicated a more uniform pore formation and increased permeability with DR. Furthermore, it was found that lower interphase content in the films with higher DR favors lamellar separation. However, permeability in the stretched precursor films with DR higher than a certain level (DR 5 93) was not improved significantly. Moreover, crystallinity and crystal orientation of produced membranes were investigated.

show abstract

Influence of Melt-Draw Ratio on the Crystalline Structure and Properties of Polypropylene Cast Film and Stretched Microporous Membrane

Cited by 34 publications

References 51 publications

Cavitation‐Induced Stress Whitening in Semi‐Crystalline Polymers

Cavitation‐Induced Stress Whitening in Semi‐Crystalline Polymers

Influences of melt-draw ratio and annealing on the crystalline structure and orientation of poly(4-methyl-1-pentene) casting films

Influence of precursor film microstructure on properties of HDPE microporous membranes prepared by stretching

Contact Info

Product

Resources

About