Relation between polymer strength and molecular orientation

Zhurkov, S. N.; Novak, I. I.; Levin, B. Ya.; Savitskii, A. V.; Vettegren, V. I.

doi:10.1016/0032-3950(65)90204-2

Cited by 32 publications

(7 citation statements)

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“…The dumbbell specimen was prepared for melt drawing by placing it on the hot shoe whose temperature was controlled to within a degree, till it became transparent, thus indicating that it had melted. 3 shows that this is not due to a conventional fibrillar structure but is the result of a special shish-kebab morphology, such as previously observed [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] in fibers made from melt extrusion at temperatures just above the (ambient) melting point. After drawing to the maximum, the drawn films were removed from the hot shoe and cooled in air while holding the ends in tension between the pliers, so as to prevent retraction.…”

Section: Experimental and Resultsmentioning

confidence: 67%

“…It is on record that under appropriate circumstances PE and other polymers can be drawn above the conventional melting point [17][18][19]. In this laboratory, H. Jenkins noted that compression moulded ultrahigh molecular weight (UHMW) PE, Hostalen GUR 415, could be drawn in the molten state at around 150 ~ but rather surprisingly, not at 160 ~ and above [18].…”

Section: Introductionmentioning

confidence: 99%

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Melt drawing as a route to high performance polyethylene

Bashir

Keller

1989

Colloid & Polymer Sci

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Well established routes for obtaining stiff and strong polyethylene (PE) involve solid state drawing either of solution crystallized gel films or melt crystallized spherulitic PE. The aim of this work is to show the potential of melt deformation as an alternative route for obtaining highly oriented products. Our previous work on the melt deformation route showed that oriented PE fibers could be directly extruded under appropriately controlled conditions [8,9]. Here, we show that PE films (or filaments) can also be "melt drawn" in the temperature window 130-160 ~ thus yielding oriented products. The advantage of melt drawing over direct melt extrusion is that it allows a wider operational latitude and thus does not require such carefully controlled conditions. The morphology produced by melt deformation is different from solid state deformation and consists of extended chain fibrils with platelet overgrowths. The relative amount of fibrils and platelets depends on operating parameters. The temperature window of PE melt drawing is identified with the regime where some flow induced crystallization takes place. The conditions for melt drawability are of wider generality for crystallizable flexible chain polymers. They are: (i) adequate strain rate to overcome entropic resistance to chain extension, (ii) but not high enough to activate the elastic response of the transient networks in the entangled system, (iii) sufficient strain to fully extend the chain, (iv) appropriate temperature for flow-induced crystallization and strain hardening, and (v) cooling to freeze the oriented structure.Ultra high molecular weight PEs were not the most suitable for melt drawing due to their high recoverable elongation in the melt (melt elasticity) in addition to added limitations imposed by their nascent grain systeme. Our work suggests that an optimum molecular weight for melt drawing is M~ -(400-900) x 103 with further possibilities for improvement through multimodal distributions.

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Section: Experimental and Resultsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Melt drawing as a route to high performance polyethylene

Bashir

Keller

1989

Colloid & Polymer Sci

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“…This softening effect is probably connected to the evolution of volumetric strains caused by necking. Moreover, the constant plastic flow stress can be related to the molecular chain structure and distribution as will be explained on a macromolecular level based on the chemical reaction model presented by Zhurkov [ 20 , 21 ].…”

Section: Resultsmentioning

confidence: 99%

Static and Dynamic Properties of Semi-Crystalline Polyethylene

Huang

Feng

et al. 2016

Polymers

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Properties of extruded polymers are strongly affected by molecular structure. For two different semi-crystalline polymers, low-density polyethylene (LDPE) and ultra-high molecular weight polyethylene (UHMWPE), this investigation measures the elastic modulus, plastic flow stress and strain-rate dependence of yield stress. Also, it examines the effect of molecular structure on post-necking tensile fracture. The static and dynamic material tests reveal that extruded UHMWPE has a somewhat larger yield stress and much larger strain to failure than LDPE. For both types of polyethylene, the strain at tensile failure decreases with increasing strain-rate. For strain-rates 0.001-3400 s´1, the yield stress variation is accurately represented by the Cowper-Symonds equation. These results indicate that, at high strain rates, UHMWPE is more energy absorbent than LDPE as a result of its long chain molecular structure with few branches.

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“…Tensile strength yarn was influenced by the degree of orientation. Yarn with a better orientation degree had better tensile strength [28]. The drafting process that caused by winding speed affected the orientation process of the yarn structure, if the cooling rate is slower than winding speed, the stretch of yarn will be higher so that the crystal structure of the yarn will be better oriented and amorphous phase will decrease [29].…”

Section: Physical and Mechanical Properties Test Resultsmentioning

confidence: 99%

The Utilization of Pet Waste as Raw Material for Producing Monofilament Yarn : The Effect of Winding Speed on the Physical and Mechanical Properties of the Yarn

Abdurrohman

Putra

Abdulllah

2020

jsmi

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THE UTILIZATION OF PET WASTE AS RAW MATERIAL FOR PRODUCING MONOFILAMENT YARN : THE EFFECT OF WINDING SPEED ON THE PHYSICAL AND MECHANICAL PROPERTIES OF THE YARN. Plastic waste production in Indonesia is quite high, reaching 15% to the total national waste production or 189-kilo tons/day with an average growth of 14.7% per year, the second biggest contributor after organic waste. This fact greatly affects human health and the environment since plastic is difficult to degrade, estimated to require 100 to 500 years for the plastic to decompose completely. Therefore, recycling becomes a popular solution to reduce waste or plastic waste by turning it into new products that have added value. Plastic materials, such as PET, have thermoplastic properties which become a special potential to use as recycled materials. The aim of this research was to study the ability of PET plastic waste as a raw material for making monofilament yarn by melt-spinning methods. PET plastic waste is melted at 250-260 °C, then is extruded using a prototype melt-spinning tool with a single spinneret hole which the diameter is 3 mm into a monofilament yarn using three variations of winding speed (a) 43.33 m/min, (b) 59.35 m/min and (c) 72.72 m/min The results showed that the yarn with the highest winding speed (variation C) produced yarn with the highest fineness, reaching (30.06± 4.82) denier, and the best tensile strength compared with the other, reaching (47.7±14,97) MPa with elongation of of (10± 9.65) %.

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Relation between polymer strength and molecular orientation

Cited by 32 publications

References 0 publications

Melt drawing as a route to high performance polyethylene

Melt drawing as a route to high performance polyethylene

Static and Dynamic Properties of Semi-Crystalline Polyethylene

The Utilization of Pet Waste as Raw Material for Producing Monofilament Yarn : The Effect of Winding Speed on the Physical and Mechanical Properties of the Yarn

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