1:30 pm – 6:00 pm:
M17-Rotational Molding: New Materials for Rotational Molding
(Moderator: Denis Rodrigue)-Room S320A
Enrico Costantini, Chief Technology Officer , SABO SpA
Rotomolding market overview – Market segments and requirements – Present solutions for UV stabilization – Development of a “new systems” with superior UV resistance: EXP UV 0117 and 0217 and EXP blends – Summary of recommendations: For both general applications and those with special requirements.
Felipe Gomes, McMaster University
Achieving optimal quality for rotational molded parts requires a determination of specific conditions for oven temperature and heat/cool time. Traditional tests used to assess the quality of these samples rely on destructive methods, such as impact testing. This paper presents an innovative approach using ultrasonic testing associated with multivariate statistical modeling to evaluate the quality of molded polyethylene (PE) parts from several different batches. Results showed a good correlation of predicted quality using non-destructive data with both impact energy failure and melt flow index, indicating the potential of this technique to be applied on the quality monitoring of this process.
2:30 pm – 3:00 pm:
3D Characterization and Mechanical Analysis of Polyethylene Foams Processed in Rapid Rotational Foam Molding
Wing Yi Pao, University of Ontario Institute of Technology
Rapid Rotational Foam Molding (RRFM) products are integral cellular composites that consist of a solid skin which encapsulates a foamed core. This paper focuses on characterizing the morphologies in 3D and identifying the key mechanical properties of respective integral-skin polyethylene (PE) cellular structures produced in RRFM by making use of Micro-CT Scanner. Two types of PE grades were used to produce the foamed core, whereas a PE and a PP grade were used to produce the surrounding solid skin layer. The effects of varying relevant processing parameters such as: foam filling directions, processing temperatures and skin temperatures on the quality of the obtained foams were studied. In addition, the correlations between the resulting cellular structures, cell size distributions, and cell densities have been assessed. Finally, simultaneous stress-strain behavior and 3D structure changes were monitored with in-situ compression testing. The experimental results revealed that foam layers adjacent to the integral skin solid layer demonstrate a higher cell density compared to those located in the core, which affects the compressive strength of the material by 0.2 MPa. It was also observed that higher processing and skin temperatures cause increase in cell size, and conversely, decrease in cell density. Mechanical analysis results indicated that cellular structures near the skin have higher compressive strength, and in general, the manufactured LLDPE foam exhibited higher mechanical properties than the sHDPE foam. Compression tests revealed that foam cell size decreases through compression, while cell density was not specifically affected with increased strain.
3:00 pm – 3:30 pm:
3-Dimensional Characterization of the Quality of Foam-to-Skin Bonding of Rapid Rotationally Foam Molded Integral-skin Cellular Composites
Utkarsh, University of Ontario Institute of Technology
Rapid Rotational Foam Molding (RRFM) was used to manufacture integral-skin composites consisting of various combinations of polyethylene (PE) and polypropylene (PP) skins that are completely surrounding respective foamed cores made of PE and PP by implementing a suitable chemical blowing agent (CBA) in extrusion. This paper presents the results of implementing a comprehensive 3-dimensional (3-D) characterization technique for evaluating the quality of the obtained foam-to-skin inter-facial bond of such RRFM composites. As the internal cellular structure and bonding depends on different polymer material properties and processing conditions, a 3-D model was developed to map the region of bubble-into-skin penetration, using a micro CT scanner. The experimental results revealed that the reconstructed 3-D model of LLDPE skin has the best bond quality and cell penetration into the skin with porosity of 74.6%.
3:30 pm – 4:00 pm:
Surface Treatment of Agave Fibers and its Compatibilization with PLA to Produce Rotational Molded Biocomposites
Jorge Robledo-Ortíz, Universidad de Guadalajara
The aim of this work was to evaluate the effect of surface treating agave fibers on the compatibility of PLA-agave biocomposites produced by rotational molding. The agave fibers were treated by immersion in a solution of maleic anhydride grafted PLA (MAPLA). The treatment effect on the physical and mechanical properties was investigated at different fiber loads (10, 20, 30 wt.%). The improved compatibility due to the grafting of PLA chains onto the fiber led to enhanced mechanical properties in comparison with untreated fiber biocomposites as a result of an effective stress transfer. In particular, tensile strength increased from 25 to 41 MPa and modulus from 1.30 to 1.74 GPa at 20 wt.%. It was possible to observe lower water diffusion coefficients indicating that grafting MAPLA decreases the fiber hydrophilicity and promotes better fiber wetting.
4:00 pm – 4:30 pm:
Mechanical Characterization of Polyethylene/Carbon Nanofiber Composites Prepared by Rotational Molding
Milton Vazquez Lepe, Universidad de Guadalajara
Nanocomposites of linear medium density polyethylene (LMDPE) and carbon nanofibers (CNFs) treated with oxygen cold plasma were prepared by rotational molding, mixing 0.01, 0.1 and 1% wt. of CNFs by dry-blending. The objective of this work is to study the influence, the change in surface chemistry and morphology in the carbon nanofibers. And thus, the effect on morphology and mechanical properties of this nanocomposites. The results indicated that the plasma technique increases the oxygen functional groups in CNFs. For the nanocomposites, the addition of CNFs modifies the mechanical properties, and major changes occur when were added CNFs treated with cold oxygen plasma.
4:30 pm – 5:00 pm:
Optimization of the Rotational Molding Processiong of Agave Fiber/LMDPE Composite Materials
Pedro Ortega-Gudiño, Researcher, Universidad de Guadalajara
In this work, agave fiber (20% wt) / LMDPE composites were processed by rotational molding with a commercial antioxidant type and UV stabilizer polyolefin additive in order to determine its influence on the process cycle. The aim was to reduce the processing temperature to ensure non-degradation of the agave fiber. The samples were mechanically characterized by impact, bending and traction tests. The results show that a biocomposite piece without imperfections can be obtained at a Peak Internal Air Temperature (PIAT) of 210ºC, which represents a reduction of the process cycle to obtain a piece with the same characteristics without additive, besides, the mechanical properties were not significantly affected.
5:00 pm – 5:30 pm:
Morphology and Mechanical Properties of Poly (Lactic Acid) / Polyethylene Blends Produced by Rotational Molding
Eduardo Ruiz Silva, Universidad de Guadalajara
Blends of poly(lactic acid) (PLA) and linear medium density polyethylene (LMDPE) at different weight ratios were prepared by rotational molding using a laboratory scale biaxial machine. The blends were previously produced by two different methods: i) dry blending using a high shear mixer and ii) melt blending with a twin-screw extruder. The prepared blends were characterized in terms of morphology, mechanical (tensile, flexion and impact) and thermal (DSC) properties. The morphological results showed a clear incompatibility between the two polymers in which the domains of the minor phase have well defined spherical shapes and a broad size distribution. On the other hand, the results of the mechanical properties depend of the blend preparation method. In general, blends prepared with melt blending presented a slight increase in flexural and tensile properties compared with those blends prepared via dry blending. For impact (charpy) mechanical properties, it was seen an increase until a maximum value was attained, after which the value decreased.
5:30 pm – 6:00 pm:
Rotational Molding of Hybrid Composites Based on Linear Low Density Polyethylene/Ground Tire Rubber/Maple Wood Fibers
Denis Rodrigue, Universit
In this work, ground tire rubber (GTR) and maple wood fibers (MWF) were dry-blended with linear low density polyethylene (LLDPE) to produce hybrid composites by rotational molding. In particular, the effect of a coupling agent (maleated polyethylene, MAPE) was studied to modify the mechanical properties of these hybrid composites. Each compound was characterized in terms of morphology, density and mechanical properties (tensile, flexural and impact). The results showed that the addition of GTR leads to limited impact strength improvement of the wood fiber composites (WFC), while MAPE addition improved the interfacial adhesion between the fibers and the matrix.