Influence of Crystal Structure on Thermo-Mechanical Properties of Injection Molded 𝛃-Nucleated iPP

2021 ◽  
Vol 36 (5) ◽  
pp. 545-556
Author(s):  
A. Hamza ◽  
R. K. Arya ◽  
A. D. Palsodkar ◽  
G. R. Bhadu ◽  
S. J. A. Rizvi
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Maleic Anhydride ◽  
Isotactic Polypropylene ◽  
Coupling Agent ◽  
Scanning Calorimetry ◽  
Slow Cooling ◽  
Melt Compounding ◽  
Crystal Fraction ◽  
Injection Molded

Abstract Isotactic polypropylene (iPP) was nucleated in-situ with calcium pimelate during melt compounding. Calcium pimelate is a highly effective β-nucleator for isotactic polypropylene (iPP). The β-nucleated iPP was characterized by wide angle x-ray diffraction (WAXD) and differential scanning calorimetry (DSC) for its crystallinity and crystal structure. In addition, the injection-molded samples were tested for thermo-mechanical properties. It is found that very low quantity (< 0.1 wt. %) of β-nucleator is required to produce sufficiently high β-crystal fraction (Kβ) in isotactic polypropylene. β-nucleated iPP shows increment of 11 to 14 °C in its heat deflection temperature (HDT). It was also observed that slow cooling rate of β-nucleated iPP promotes the formation of β-crystals and that tensile stretching leads to complete transformation of β crystals into a-crystals at room temperature. It was also revealed that the presence of maleic anhydride grafted polypropylene (PP-g-MA), a well-known coupling agent (or compatibilizer), may reduce the (Kβ) value to a marginal extent. It was also observed that the thermo-mechanical properties were not much affected by the presence of PP-g-MA. Therefore, calcium pimelate may be used as β-nucleator in case of neat as well as reinforced polypropylene containing maleic anhydride as coupling agent.

Melting, Crystallization Behaviors and Mechanical Properties of iPP Nucleated by β Nucleation Masterbatches

2014 ◽  
Vol 941-944 ◽  
pp. 1229-1232
Author(s):  
Guo Rui Dou ◽  
Qiang Dou
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Impact Strength ◽  
Isotactic Polypropylene ◽  
Tensile Strain ◽  
Mechanical Tests ◽  
Crystalline Form ◽  
Scanning Calorimetry ◽  
Crystallization Behaviors ◽  
Injection Molded

Injection-molded β-isotactic polypropylene (β-iPP) specimens were prepared by adding three β nucleation masterbatches, i.e., NT-MA, NT-MB and NT-MC, respectively. The melting, crystallization and mechanical properties of β-iPP specimens were investigated by means of differential scanning calorimetry (DSC) and mechanical tests. It is revealed that β crystalline form contents were enhanced by the β nucleation masterbatches, and the β contents of the cores were higher than those of the skins of injection molded specimens. The tensile strain at break and Izod notched impact strength of iPP were greatly improved by the β nucleation masterbatches. It was found that the β nucleation efficiency was in the order: NT-MC > NT-MA > NT-MB.

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

Materials ◽  
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.

Weldability of pipe grade polyethylenes as realized from thermal and mechanical properties assessments

2016 ◽  
Vol 36 (8) ◽  
pp. 853-860 ◽  
Author(s):  
Vahabodin Goodarzi ◽  
Zahed Ahmadi ◽  
Mohammad Reza Saeb ◽  
Farkhondeh Hemmati ◽  
Mehdi Ghaffari ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Molecular Weight ◽  
Aging Process ◽  
Pipe Production ◽  
Lamellar Thickness ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Injection Molded ◽  
The One

Abstract Since polyethylene (PE) has been widely accepted for the production of high-pressure fluid conveying pipelines, studies devoted to weldability of PE connections were always of major importance. In this study, two industrial PE grades designed for pipe production, namely PE80 and PE100, were injection molded, cut, and then welded as PE100-PE100, PE100-PE80, and PE80-PE80. The heat-welded joints were assessed by differential scanning calorimetry and tensile measurements. The results obtained from thermal and mechanical analyses were compared with equivalents for aged samples. Thermal analysis revealed that the melting point of the PE100-PE100 sample is obviously larger than the one for the PE80-PE80 joint, for the PE80 chains deteriorate the crystallization of PE100. Further, the PE80-PE80 sample showed the lowest lamellar thickness and crystalline molecular weight among the studied joints. The aging process was found to increase lamellar thickness and molecular weight, though in the PE100-PE100 sample such quantities very limitedly increased. The yield stress of aged joints was higher than that for just-prepared samples, while an inverse trend was seen for strain at break. From a practical viewpoint, the PE100-PE100 welds offer better properties.

Interfacial and Mechanical Properties of Continuous Fiber-Reinforced PP via Pre Impregnated Winding

2017 ◽  
Vol 25 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Jiuqiang Song ◽  
Yan Qin ◽  
Jia Chen ◽  
Siwen Qin
Keyword(s):  
Mechanical Properties ◽  
Maleic Anhydride ◽  
Glass Fiber ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Fiber Reinforced ◽  
Continuous Glass ◽  
Continuous Glass Fiber ◽  
Glass Fiber Reinforced ◽  
Silane Coupling

In this paper, a continuous glass fiber-reinforced polypropylene prepreg was prepared by fiber treatment with a silane coupling agent and MAH-g-PP resin. Continuous glass fiber-reinforced polypropylene sheets were made from prepreg and PP mats by hot-pressing; they displayed exceptional performance. This paper studies the effects of maleic anhydride grafting on the polypropylene crystallinity and MAH-g-PP content in the prepreg, and the mechanical properties of the composites. The results showed that modifying PP with maleic anhydride decreased the tacticity of the polypropylene molecular chain, which reduced the crystallinity and melting point. An excellent interface formed between the polypropylene and fiber after the glass fiber was treated with a silane coupling agent and MAH-g-PP resin. The mechanical properties of the polymer materials displayed more favorable properties as MAH-g-PP content increased; the ideal MAH-g-PP content was 50%.

The effect of hybrid nanoparticle with silica sol as the supporter on the crystallization behavior and mechanical properties of isotactic polypropylene

2015 ◽  
Vol 35 (6) ◽  
pp. 565-573 ◽  
Author(s):  
Juan Li ◽  
Shuhao Qin ◽  
Wentao He ◽  
Yushu Xiang ◽  
Qin Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Isotactic Polypropylene ◽  
Crystallization Behavior ◽  
Optical Microscope ◽  
Silica Sol ◽  
Hybrid Nanoparticles ◽  
Hybrid Particles ◽  
Scanning Calorimetry ◽  
Chemical Action ◽  
Time Dynamic

Abstract Colloidal dispersions of hybrid nanoparticles with silica sol as the supporter (PKSol) were prepared by supporting aromatic phosphate on silica sol via a chemical action with γ-aminopropyltrimethylsilane (KH550) as a linker in wet process for the first time. Dynamic light scattering (DLS) demonstrated that hybrid nanoparticles with an average size of about 200 nm were formed and transmission electron microscopy (TEM) confirmed the presence of the ultrafine silica sols within the hybrid particles, which exhibited “currant-bun” particle morphologies, rather than typical “core-shell” structures for most polymer-encapsulated silica particles. Compared to aromatic phosphate alone and silane-modified silica sol, the effect of PKSol on the crystallization behavior and mechanical properties of isotactic polypropylene (iPP) was investigated using a polarized optical microscope (POM) and differential scanning calorimetry (DSC). The results demonstrated that PKSol showed superior nucleating ability on iPP than the other two. After adding 0.2 wt% PKSol, the crystallization peak temperature of iPP increased from 116.35°C to 120.81°C and the crystallinity increased from 39.6% to 50%. Correspondingly, the haze decreased from 37.6% to 23.3% and mechanical properties were improved.

Shear-induced fibrillation and resultant mechanical properties of injection-molded polyamide 1010/isotactic polypropylene blends

2011 ◽  
Vol 60 (11) ◽  
pp. 1655-1662 ◽  
Author(s):  
Run Su ◽  
Kun Jiang ◽  
Yao Ge ◽  
Shanwei Hu ◽  
Zhen Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Isotactic Polypropylene ◽  
Injection Molded ◽  
Polypropylene Blends ◽  
Polyamide 1010

scholarly journals Use of Organic Acids in Bamboo Fiber-Reinforced Polypropylene Composites: Mechanical Properties and Interfacial Morphology

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2007
Author(s):  
Lety del Pilar Fajardo Cabrera de Lima ◽  
Cristian David Chamorro Rodríguez ◽  
José Herminsul Mina Hernandez
Keyword(s):  
Mechanical Properties ◽  
Maleic Anhydride ◽  
Organic Acids ◽  
Coupling Agent ◽  
Flexural Modulus ◽  
Tricarboxylic Acid ◽  
Bamboo Fiber ◽  
Interfacial Bonding ◽  
Dodecanoic Acid ◽  
Interfacial Morphology

In obtaining wood polymer composites (WPCs), a weak interfacial bonding can cause problems during the processing and affect the mechanical properties of the resulting composites. A coupling agent (CA) is commonly used to solving this limitation. To improve the interfacial bonding between bamboo fiber (BF) and a polypropylene matrix, the effect of three organic acids on the mechanical properties and interfacial morphology were investigated. The BF/PP composites were prepared in five families: the first without CA, the second using a maleic anhydride-grafted polypropylene coupling agent, and the third, fourth, and fifth families with the addition of organic acids (OA) tricarboxylic acid (TRIA), hexadecanoic acid (HEXA), and dodecanoic acid (DODA), respectively. The use of OA in BF/PP improved the interfacial adhesion with the PP matrix, and it results in better mechanical performance than composites without CA. Composites coupled with MAPP, TRIA, DODA, and HEXA showed an increase in Young’s modulus of about 26%, 23%, 15%, and 16% respectively compared to the composite without CA incorporation. In tensile strength, the increase in composites with CA was about 190%, while in the flexural modulus, the coupled composites showed higher values, and the increase was more in composites with TRIA: about 46%. The improvement caused by tricarboxylic acid was similar to that promoted by the addition of maleic anhydride-grafted polypropylene (MAPP).

scholarly journals Mechanical Properties, Wettability and Thermal Degradation of HDPE/Birch Fiber Composite

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1459
Author(s):  
Agbelenko Koffi ◽  
Fayçal Mijiyawa ◽  
Demagna Koffi ◽  
Fouad Erchiqui ◽  
Lotfi Toubal
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Thermal Degradation ◽  
Coupling Agent ◽  
High Density Polyethylene ◽  
Fiber Composite ◽  
Flexural Modulus ◽  
High Density ◽  
Wood Fibers ◽  
Scanning Calorimetry

Wood–plastic composites have emerged and represent an alternative to conventional composites reinforced with synthetic carbon fiber or glass fiber–polymer. A wide variety of wood fibers are used in WPCs including birch fiber. Birch is a common hardwood tree that grows in cool areas such as the province of Quebec, Canada. The effect of the filler proportion on the mechanical properties, wettability, and thermal degradation of high-density polyethylene/birch fiber composite was studied. High-density polyethylene, birch fiber and maleic anhydride polyethylene as coupling agent were mixed and pressed to obtain test specimens. Tensile and flexural tests, scanning electron microscopy, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetry analysis and surface energy measurement were carried out. The tensile elastic modulus increased by 210% as the fiber content reached 50% by weight while the flexural modulus increased by 236%. The water droplet contact angle always exceeded 90°, meaning that the material remained hydrophobic. The thermal decomposition mass loss increased proportional with the percentage of fiber, which degraded at a lower temperature than the HDPE did. Both the storage modulus and the loss modulus increased with the proportion of fiber. Based on differential scanning calorimetry, neither the fiber proportion nor the coupling agent proportion affected the material melting temperature.

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