The Friction of Structurally Modified Isotactic Polypropylene

The purpose of studies was to analyse an impact of heterogeneous nucleation of modified isotactic polypropylene (iPP) on its tribological properties. The iPP injection molded samples, produced by mold temperature of 20 and 70 °C, were modified with compositions of two nucleating agents (NA’s), DMDBS creating α-form and mixture of pimelic acid with calcium stearate (PACS) forming β–phase of iPP, with a total content 0.2 wt.% of NA’s. A polymorphic character of iPP, with both, monoclinic (α) and pseudo-hexagonal (β) crystalline structures, depending on the NA’s ratio, was verified. The morphology observation, DSC, hardness and tribological measurements as test in reciprocating motion with “pin on flat” method, were realized, followed by microscopic observation (confocal and SEM) of the friction patch track. It was found that Shore hardness rises along with DMBDS content, independent on mold temperature. The friction coefficient (COF) depends on NA’s content and forming temperature—for upper mold temperature (70 °C), its value is higher and more divergently related to NA’s composition, what is not the case by 20 °C mold temperature. The height of friction scratches and the width of patch tracks due to its plastic deformation, as detected by confocal microscopy, are related to heterogeneous nucleation modified structure of iPP.

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The use of IR thermography to show the mold and part temperature evolution in injection molding

Archives of Mechanical Technology and Materials ◽

10.1515/amtm-2016-0008 ◽

2016 ◽

Vol 36 (1) ◽

pp. 40-43 ◽

Cited By ~ 1

Author(s):

Karol Bula ◽

Leszek Różański ◽

Lidia Marciniak-Podsadna ◽

Dawid Wróbel

Keyword(s):

Injection Molding ◽

Isotactic Polypropylene ◽

Infrared Camera ◽

Mold Temperature ◽

Temperature Evolution ◽

Injection Mold ◽

Ir Thermography ◽

Molded Parts ◽

Injection Molded

Abstract This study concerns the application of infrared camera for injection molding analysis by measuring temperatures of both injection molded parts and injection mold cavities in a function of injection cycles. The mold with two cavities, differing in thickness (1 and 3 mm), and a cold direct runner was used. Isotactic polypropylene homopolymer was utilized to produce parts. Mold temperature was set at 22°C and controlled by a water chiller. Five measuring points were determined: SP1, SP2 (placed in the 3 mm cavity), SP3, SP4 (located in the 1 mm cavity) and SP5 around an injection molding gate. Our investigations showed that the highest temperature is localized around SP2 point and the lowest at SP4. Also, it was proved that even after 62 injection molding cycles, temperatures of cavities were not stable, revealing their further increase with each cycle.

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Transition from the hierarchical distribution to a homogeneous formation in injection molded isotactic polypropylene (iPP) with dynamic mold temperature control

Polymer Testing ◽

10.1016/j.polymertesting.2017.04.012 ◽

2017 ◽

Vol 60 ◽

pp. 299-306 ◽

Cited By ~ 4

Author(s):

Haibin Zhao ◽

Xue Liu ◽

Yang Sui ◽

Yanan Zhang ◽

Guoqun Zhao

Keyword(s):

Temperature Control ◽

Isotactic Polypropylene ◽

Mold Temperature ◽

Injection Molded ◽

Homogeneous Formation

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Molecular weight dependency of β phase formation in injection‐molded isotactic polypropylene

Journal of Applied Polymer Science ◽

10.1002/app.48555 ◽

2019 ◽

Vol 137 (15) ◽

pp. 48555 ◽

Cited By ~ 3

Author(s):

Xiao Yang ◽

Cristina Tuinea‐Bobe ◽

Ben Whiteside ◽

Phil Coates ◽

Ying Lu ◽

...

Keyword(s):

Molecular Weight ◽

Phase Formation ◽

Isotactic Polypropylene ◽

Β Phase ◽

Injection Molded

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The Relationship between Structure and Properties of β-Phase Isotactic Polypropylene

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.233-235.2129 ◽

2011 ◽

Vol 233-235 ◽

pp. 2129-2137 ◽

Cited By ~ 3

Author(s):

Yuan Hong Shi ◽

Qiang Dou

Keyword(s):

Impact Strength ◽

Isotactic Polypropylene ◽

Crystal Morphology ◽

Mechanical Tests ◽

Strength Increase ◽

Structure And Properties ◽

Β Phase ◽

Injection Molded ◽

The Relationship ◽

Melting And Crystallization

In this paper, β-phase isotactic polypropylene (β-iPP) was prepared with two different β nucleating agents (NT-A and NT-D). The melting and crystallization behavior, crystal morphology and mechanical properties of β-iPP were studied by means of DSC, WAXD, PLM and mechanical tests. It is found that the spherulites become smaller, and tensile strength, tensile strain at break and notched impact strength increase for the nucleated iPP. NT-D is more efficient than NT-A. The notched impact strength is three times greater than that of pure iPP for the samples nucleated by NT-D. The injection molded specimens have obvious skin-core structures.

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Nucleating agents based on graphene and graphene oxide for crystallization of the β-form of isotactic polypropylene

Journal of Materials Science ◽

10.1007/s10853-019-04045-y ◽

2019 ◽

Vol 55 (4) ◽

pp. 1436-1450 ◽

Cited By ~ 7

Author(s):

Jan Broda ◽

Marcin Baczek ◽

Janusz Fabia ◽

Dorota Binias ◽

Ryszard Fryczkowski

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Isotactic Polypropylene ◽

Reduced Form ◽

Pimelic Acid ◽

Nucleating Agents ◽

Scanning Calorimetry ◽

Functionalized Graphene Oxide ◽

Reduced Graphene ◽

Carboxylic Groups

Abstract During the investigations, functionalization of graphene oxide synthesized using modified Hummers’ method and its reduced form was performed. Mixtures of graphene oxide and reduced graphene oxide with pimelic acid and calcium hydroxide were prepared for functionalization. During the reaction, the molecules of pimelic acid were attached to the surface of graphene sheets. By forming links between the carboxylic groups of pimelic acid and graphene oxide, the durable connection was achieved. The functionalized graphene oxide and the reduced graphene oxide were used as additives in isotactic polypropylene crystallization. The influence of additives on crystallisation in non-isothermal conditions was examined using polarized optical microscopy and differential scanning calorimetry. The effect of the additives on the polypropylene structure was analysed using wide-angle X-ray scattering. For both functionalized compounds, the nucleating ability towards β-form of polypropylene was detected. Both additives showed the increase in the nucleation rate and promotion of growth of the β-form crystals. Nucleation efficiency similar to other nucleating agents used in the crystallization of the β-form of polypropylene was revealed.

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Plastic deformation of oriented lamellae: 3. Drawing behaviour of β-phase isotactic polypropylene

Polymer ◽

10.1016/0032-3861(83)90216-1 ◽

1983 ◽

Vol 24 (7) ◽

pp. 925-929 ◽

Cited By ~ 40

Author(s):

T. Yoshida ◽

Y. Fujiwara ◽

T. Asano

Keyword(s):

Plastic Deformation ◽

Isotactic Polypropylene ◽

Β Phase

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Plastic Deformation of Oriented Lamellae. II. Hot Rolling of β-Phase Isotactic Polypropylene

Polymer Journal ◽

10.1295/polymj.11.383 ◽

1979 ◽

Vol 11 (5) ◽

pp. 383-390 ◽

Cited By ~ 32

Author(s):

Tsutomu Asano ◽

Yasuna Fujiwara ◽

Toshiho Yoshida

Keyword(s):

Plastic Deformation ◽

Isotactic Polypropylene ◽

Hot Rolling ◽

Β Phase

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Post-Processing Time Dependence of Shrinkage and Mechanical Properties of Injection-Molded Polypropylene

Materials ◽

10.3390/ma14010022 ◽

2020 ◽

Vol 14 (1) ◽

pp. 22

Author(s):

Artur Kościuszko ◽

Dawid Marciniak ◽

Dariusz Sykutera

Keyword(s):

Mechanical Properties ◽

Impact Strength ◽

Injection Molding ◽

Accelerated Aging ◽

Mold Temperature ◽

Degree Of Crystallinity ◽

Injection Mold ◽

Secondary Crystallization ◽

Scanning Calorimetry ◽

Injection Molded

Dimensions of the injection-molded semi-crystalline materials (polymeric products) decrease with the time that elapses from their formation. The post-molding shrinkage is an effect of secondary crystallization; the increase in the degree of polymer crystallinity leads to an increase in stiffness and decrease in impact strength of the polymer material. The aim of this study was to assess the changes in the values of post-molding shrinkage of polypropylene produced by injection molding at two different temperatures of the mold (20 °C and 80 °C), and conditioned for 504 h at 23 °C. Subsequently, the samples were annealed for 24 h at 140 °C in order to conduct their accelerated aging. The results of shrinkage tests were related to the changes of mechanical properties that accompany the secondary crystallization. The degree of crystallinity of the conditioned samples was determined by means of density measurements and differential scanning calorimetry. It was found that the changes in the length of the moldings that took place after removal from the injection mold were accompanied by an increase of 20% in the modulus of elasticity, regardless of the conditions under which the samples were made. The differences in the shrinkage and mechanical properties of the samples resulting from mold temperature, as determined by tensile test, were removed by annealing. However, the samples made at two different injection mold temperature values still significantly differed in impact strength, the values of which were clearly higher for the annealed samples compared to the results determined for the samples immediately after the injection molding.

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