Effect of oven residence time on mechanical properties in rotomoulding of LLDPE

Ramkumar, Pl.; Waigaonkar, Sachin; Kulkarni, Deepak

doi:10.1007/s12046-016-0489-4

Cited by 14 publications

(6 citation statements)

References 20 publications

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“…Previous studies (Xu and Crawford, 1993;Oliveira et al, 1996Oliveira et al, , 2007Pick and Harkin-Jones, 2004) reported a correlation between the number of voids and the impact strength in rotational molded parts; the greater the number of voids, the lower the impact resistance. Moreover, according to Oliveira et al (2007) and Ramkumar et al (2016), there is a processing window that maximizes the mechanical properties as a result of better sintering (reduction of voids) and the absence of thermal degradation of the polymer matrix. In the present study, cork hinders the formation of a well-compacted structure, as observed previously by SEM.…”

Section: Mechanical Properties Of Partsmentioning

confidence: 99%

Processing–Structure–Properties of Cork Polymer Composites

Martins

Gil

2020

Front. Mater.

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This work aims at presenting a new strategy for the use of cork by-products on the development of sustainable composites with potential applications in rotational molding. In this study, different cork granulometries (0.15-3 mm) and matrix/cork ratios (90/10, 85/15, 80/20) are analyzed to access the processability of medium-density polyethylene (MDPE) with cork by rotational molding. The influence of processing parameters, such as the mold peak internal air temperature (PIAT) (200-240 • C), is analyzed and correlated with the aesthetics, morphological and mechanical properties of the parts. The aim is to obtain a complete understanding of the processing-structure-property relationships. Defect-free parts are obtained with thin granulometric cork powders at a maximum of 10% by weight in PE/cork composites. The increase in cork content reduces the sintering capability and increases the porosity, wall thickness, and surface defects, simultaneously weakening the mechanical properties. The increase in PIAT favors a more compact structure and reveals better impact properties. All the parts are soft on touch and transmit the comfort and sensation of warm feeling of the cork. Moreover, lightweight parts and hydrophobic surfaces are achieved from the cork intrinsic properties. As a natural material, cork darkens its color with temperature, which is attributed to the reactions of the extractives within the components of cork, with no degradation associated. The work shows that polymer cork composites (CPC) are suitable for rotational molding within the processing window characteristic of PE, to achieve innovative and sustainable products with unique aesthetics and functionalities given by the cork material.

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Section: Mechanical Properties Of Partsmentioning

confidence: 99%

Processing–Structure–Properties of Cork Polymer Composites

Martins

Gil

2020

Front. Mater.

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“…This is crucial for the mechanical properties of the finished part such as tensile, impact, and flexural strength. [7][8][9] The powder-mold contact time is critical to allow the most heat energy to transfer to the powder bed through conduction (the dominant means of heat transfer) over a set period. 10 An appropriate speed would allow sufficient time for the heat energy from the mold to transfer to the powder.…”

Section: Literature Reviewmentioning

confidence: 99%

“…The rotational speed and speed ratio determine the number of times a specific area on the mold wall passes through the powder bed and the direction in which it enters and exits the powder bed. This is crucial for the mechanical properties of the finished part such as tensile, impact, and flexural strength 7–9 . The powder‐mold contact time is critical to allow the most heat energy to transfer to the powder bed through conduction (the dominant means of heat transfer) over a set period 10 .…”

Section: Literature Reviewmentioning

confidence: 99%

Motion control for uniaxial rotational molding

Adams

Jin

Barnes

et al. 2020

J of Applied Polymer Sci

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Motion control parameters of rotational molding can affect process efficiency and product quality. Different motion control schemes will lead to varied powder flow regimes exhibiting different levels of mixing and temperature uniformity. The change in nature of powder flow during a molding cycle suggests that varying the rotational speed could improve the powder mixing and temperature uniformity, therefore potentially reducing processing time and energy consumption. Experiments completed investigating powder flow under uniaxial rotation show that savings of up to 2.5% of the heating cycle time can be achieved. This validates the hypothesis that altering the rotational speed to maintain the ideal powder flow throughout the heating cycle can be utilized to reduce the time taken for all the polymer powder to adhere to the mold wall. The effect of rotational speed on wall thickness uniformity and impact strength were investigated and discussed. Results show a strong influence of rotational speed (and powder flow) on the wall thickness uniformity of the moldings with wall thickness uniformity deviations of up to 50% found (within the 2-35 RPM speed range tested).

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“…But, because of its low melting point, low cost and good thermal stability, polyethylene (PE) is primarily used worldwide, with about 85% of the rotomolded components. 12 However, PE has modest mechanical properties compared to other materials which prevent its use in multiple applications. 13…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of linear low density polyethylene composites based on coir for rotational molding process

Gupta

Ramkumar

2020

Polymers and Polymer Composites

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Rotational Molding is a plastic manufacturing process mainly implemented to produce stress free hollow products. Linear Low Density Polyethylene (LLDPE) is widely preferred as base resin for molding roto molded product, but it displays moderate value in some critical applications where strength is the major criteria. Additives can fill the gap in sustaining the necessary strength needed. In the present work, an attempt has been made to analyze the optimum percentage of coir reinforced with LLDPE for rotational molding technique to provide requisite processability for rotational molding process. Coir in its powder form is mixed at concentrations varying in the range of 3% to 20% with respect to LLDPE. In order to justify the prerequisite of processability for rotational molding, various experiments namely FTIR, MFI, rheology and thermal analysis were conducted. FTIR suggested the range of 5% to 15% wherein the significance of LLDPE and coir peaks can be observed. MFI test supported FTIR result which ended in considering 3% to 12% by weight ratio suitable in terms of flow ability. Rheological and thermal analysis subjecting to shear and heat parameter respectively, confirmed the range of 10 weight percentage of coir or below is suitable in terms of material processability. From the experimental results, it is concluded that 10% or less concentration of coir fiber in LLDPE as an optimum range of blend yielding better processability for rotational molding process.

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Effect of oven residence time on mechanical properties in rotomoulding of LLDPE

Cited by 14 publications

References 20 publications

Processing–Structure–Properties of Cork Polymer Composites

Processing–Structure–Properties of Cork Polymer Composites

Motion control for uniaxial rotational molding

Experimental investigation of linear low density polyethylene composites based on coir for rotational molding process

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