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.

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

2016 ◽  
Vol 36 (1) ◽  
pp. 40-43 ◽  
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.

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.

Assessment of a Polyamide Used in Flexible Pipes After Aging in Deoxygenated Water

2020 ◽  
Author(s):  
Danyelle Costa ◽  
Geovanio Oliveira ◽  
Leilane Cirilo ◽  
Marysilvia Costa
Keyword(s):  
Mechanical Properties ◽  
Aging Time ◽  
High Performance ◽  
Accelerated Aging ◽  
Volumetric Analysis ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polyamide 12 ◽  
Flexible Pipes ◽  
Indentation Tests

Abstract A high-performance polyamide grade of easy processability which presents excellent thermal and mechanical properties such as resistance to fatigue and creep is studied in this work. An accelerated aging of Polyamide 12 samples was performed in stainless steel autoclaves at 120°C in deoxygenated water at pH 8.7 in order to shorten the aging time and avoid oxidation. The samples were retrieved at distinct aging times which were enough to reach the asymptotic portion of the curve of corrected inherent viscosity (CIV) versus aging time. CIV measurements track modifications of the molecular weight due to hydrolysis. Afterwards, the samples were analyzed through their cross section in the core and edge layer in order to investigate changes due to diffusion effects. Differential scanning calorimetry (DSC) analysis assesses the degree of crystallinity and melting temperature. Thermogravimetric analysis (TGA) was employed in order to investigate changes in the thermal stability and the stage of degradation of the samples. Unlike conventional volumetric analysis techniques, the instrumented indentation tests (IIT) in micro-scale were performed to measure the mechanical properties such as elastic modulus (EIT) and hardness (HIT) along the thickness aiming to detect properties gradient between surface and core. The CIV measurements showed a decrease of 46.3% in the aged sample during the maximum aging time compared to the reference material.

Injection Molding of PC/PMMA Blend for Fabricate of the Secondary Optical Elements of LED Illumination

2012 ◽  
Vol 579 ◽  
pp. 134-141 ◽  
Author(s):  
Hoang Van Thanh ◽  
Chao Chang Arthur Chen ◽  
Chia Hsing Kuo
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Injection Molding ◽  
Mold Temperature ◽  
Injection Molding Process ◽  
Molding Process ◽  
Melt Temperature ◽  
Maximum Tensile Strength ◽  
Pmma Blends

This paper is to investigate the optimization of mechanical properties for the maximum tensile strength, elongation, and impact strength of Polycarbonate and Polymethyl methacrylate (PC/PMMA) blends by injection molding process. The PC/PMMA plastics composites with different blending percentage are first blended have been injected as the tensile and impact specimens designed according to ASTM, type V by injection molding machine. Taguchi’s method is then used to find the optimal parameters for the maximum tensile strength, elongation and impact strength. The control factors selected in this study are melt temperature, packing pressure, mold temperature and cooling time. An ANOVA table has been used for determining the significance of injection molding parameters. Results of experiments show that the melt temperature is the most significant parameter for improvement of mechanical properties of PC-PMMA plastics composites. Blends with high PC concentrations result in low tensile strength and high impact strength. Illumination testing of the tatol internal reflection (TIR) of PC/PMMA blends has been proceeded and the TIR lens illumination intensity is compared with three compositions of the PC/PMMA blends. Illumination results show that the PC/PMMA 80/20 blend has the highest intensity of illumination. Results of this study can be applied on the optimization of injection molding parameters for polymer blends of LED lens.

Effect of injection parameters on the thermal, mechanical and thermomechanical properties of polycaprolactone (PCL)

2021 ◽  
pp. 009524432110153
Author(s):  
Carlos Bruno Barreto Luna ◽  
Danilo Diniz Siqueira ◽  
Eduardo da Silva Barbosa Ferreira ◽  
Edcleide Maria Araújo ◽  
Renate Maria Ramos Wellen
Keyword(s):  
Experimental Design ◽  
Impact Strength ◽  
Injection Molding ◽  
Mold Temperature ◽  
Degree Of Crystallinity ◽  
Injection Molding Process ◽  
Processing Temperature ◽  
Molding Process ◽  
Injection Flow ◽  
The Impact

In this work, an experimental design was applied in the injection molding process of polycaprolactone (PCL), aiming to evaluate the mechanical properties (impact strength, tensile strength and Shore D Hardness), thermal (differential scanning calorimetry (DSC)) and thermomechanical (heat deflection temperature (HDT)), in PCL injected specimens. A type 2n planning was applied, with n = 3 and central point, having the input factors: processing temperature profile, mold temperature and injection flow. The results showed that the DSC curves presented a complex mechanism during crystallization, suggesting that depending on the processing conditions a high degree of crystallinity can be obtained. When using a higher processing temperature and a higher injection flow, there is an increase in the mass of the PCL parts. The impact strength is more expressive when a higher injection flow and a lower processing temperature are applied, reaching values around 260 J/m. The mold temperature impairs the elongation at the break of the PCL, while the elastic modulus was governed by the degree of crystallinity. A deleterious effect on HDT was observed with increased injection flow, suggesting that this parameter negatively affects thermomechanical resistance. The use of experimental design in the processing of PCL is important, since it is possible to optimize properties with the ideal conditions of injection molding.

scholarly journals The Effect of Mold Conditions on Heat Resistance of Injection-Molded Stereocomplex Polylactide-b-polyethylene Glycol-b-Polylactide Bioplastic

2021 ◽  
Vol 58 (3) ◽  
pp. 11-22
Author(s):  
Yodthong Baimark ◽  
Wuttipong Rungseesantivanon ◽  
Natcha Prakymoramas
Keyword(s):  
Polyethylene Glycol ◽  
Heat Resistance ◽  
Softening Temperature ◽  
Mold Temperature ◽  
Mechanical Analysis ◽  
Cooling Time ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Injection Molded ◽  
Good Heat

The effect of mold conditions was investigated in terms of mold temperature (30oC and 90oC) and cooling time (30 s and 60 s) on the heat resistance of injection-molded bars for stereocomplex polylactide-b-polyethylene glycol-b-polylactide (scPLA-PEG-PLA). Comparative study was performed for poly(L-lactide) (PLLA) and PLLA-b-PEG-b-PLLA (PLLA-PEG-PLLA). scPLA-PEG-PLA was 90/10 (w/w) PLLA-PEG-PLLA/poly(D-lactide) blend. scPLA-PEG-PLA exhibited the easiest crystallization upon cooling scan as shown by differential scanning calorimetry (DSC). Higher mold-temperature and longer cooling-time induced higher degree of crystallinity as assessed by X-ray diffractometry (XRD) except for PLLA bars. The heat resistance of both PLLA-PEG-PLLA and scPLA-PEG-PLA bars was improved with increased mold-temperature and cooling-time as shown by dynamic mechanical analysis (DMA), vicat softening temperature (VST) and heat distortion-resistance tests except for PLLA bars. In conclusion, the heat resistance of injection-molded bars prepared at 90˚C mold temperature was in the order scPLA-PEG-PLA ] PLLA-PEG-PLLA ] PLLA. The results suggested that flexible PLLA-PEG-PLLA and scPLA-PEG-PLA with high degrees of crystallinity were successfully obtained by injection molding for use as good heat-resistant bioplastic products.

Mechanical Properties of Injection Molded Rubber Testing Samples

2015 ◽  
Vol 752-753 ◽  
pp. 308-311
Author(s):  
Adam Skrobak ◽  
Michal Stanek ◽  
David Manas ◽  
Martin Ovsik ◽  
Vojtech Senkerik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Standardized Testing ◽  
Rubber Compound ◽  
Testing Sample ◽  
Synthetic Rubber ◽  
Injection Molded

The aim of this article is to demonstrate and asses to what extent there is an impact on the mechanical properties of a standardized testing sample made of rubber compound based on synthetic rubber EPDM and produced by injection molding in comparison with a sample produced by classic preparation (cutting off a compression molded plate) according to the standard ISO 23529.

Microstructure, Hardness, and Wear Resistance of Powder-Injection-Molded Products of Fe-Based Metamorphic Powders

2007 ◽  
Vol 26-28 ◽  
pp. 355-358
Author(s):  
Chang Kyu Kim ◽  
Chang Young Son ◽  
Dae Jin Ha ◽  
Tae Sik Yoon ◽  
Sung Hak Lee
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Wear Resistance ◽  
Injection Molding ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Thermally Stable ◽  
Austenitic Matrix ◽  
Amorphous Phases ◽  
Injection Molded

Powder injection molding (PIM) process was applied to Fe-based metamorphic alloy powders, and microstructure, hardness, and wear resistance of the PIM products were analyzed and compared with those of conventional PIM stainless steel products. When Fe-based metamorphic powders were injection-molded and then sintered at 1200 oC, completely densified products with almost no pores were obtained. They contained 34 vol.% of (Cr,Fe)2B borides dispersed in the austenitic matrix without amorphous phases. Since these (Cr,Fe)2B borides were very hard and thermally stable, hardness, and wear resistance of the PIM products of Fe-based metamorphic powders were twice as high as those of conventional PIM stainless steel products. Such property improvement suggested new applicability of the PIM products of Fe-based metamorphic powders to structures and parts requiring excellent mechanical properties.

scholarly journals Mechanical Properties Distribution within Polypropylene Injection Molded Samples: Effect of Mold Temperature under Uneven Thermal Conditions

Polymers ◽  
2017 ◽  
Vol 9 (11) ◽  
pp. 585 ◽  
Author(s):  
Sara Liparoti ◽  
Vito Speranza ◽  
Andrea Sorrentino ◽  
Giuseppe Titomanlio
Keyword(s):  
Mechanical Properties ◽  
Thermal Conditions ◽  
Mold Temperature ◽  
Injection Molded

scholarly journals The Effect of Crystallinity on the Toughness of Cast Polyamide 6 Rods with Different Diameters

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 293
Author(s):  
Miklós Odrobina ◽  
Tamás Deák ◽  
László Székely ◽  
Tamás Mankovits ◽  
Róbert Zsolt Keresztes ◽  
...  
Keyword(s):  
Impact Strength ◽  
Impact Test ◽  
Charpy Impact ◽  
Polyamide 6 ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Tensile Impact ◽  
Different Diameters ◽  
The Impact ◽  
The Degree Of Crystallinity

The present paper concentrates on the toughness and the degree of crystallinity of the magnesium-catalyzed polyamide 6 rods cast in different diametres, which are commonly used for gear manufacturing. Its toughness cannot be regarded as a constant feature due to the casting technology. The mechanical properties of the semi-finished products are sensitive to the manufactured dimension, e.g., cast diameter, which are investigated by the Charpy impact test and tensile impact test. It is generally accepted that the impact strength and tensile-impact strength correlate with the degree of crystallinity beside many other material’s feature. Crystallinity is evaluated by Differential Scanning Calorimetry. The aim of this study is to determine the relationship between toughness and crystallinity of the magnesium-catalyzed cast PA6 rods with different diameters. For the research cast rods between 40 and 300 mm diameter were selected in seven-dimensional steps. Based on the results, it was found that the toughness depends strongly on the diameter size. Furthermore, it is proved that the crystallinity explains 62.3% of the variation of the Charpy’s impact strengths, while the tensile impact method was not suitable to detect the difference between the test samples.

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