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High‐strength and high‐gas‐barrier plastic packaging liners have emerged as competitive products with promising potential application in the field of Type IV hydrogen storage cylinders. Ternary composites, which contain PA6, organically modified montmorillonite (OMMT), and maleic anhydride grafted polyolefin elastomer (POE‐g‐MAH), have been proposed as possible material for this application. To achieve the goal of developing this material, the influence of material formulation on various properties such as mechanical, microstructure, gas barrier, thermal stability, and flow properties of the composites was investigated. The results show that the composites with 3 wt% OMMT had the best gas barrier and mechanical properties. Additionally, the effect of rotational molding process parameters on the wall thickness of the plastic liner was studied. Process parameter regulation methods were proposed to improve wall thickness consistency of the products. The investigation shows that the composites containing 3 wt% OMMT had the best wall thickness consistency of the products. Highlights: The effect of filler content on the properties of PA6 composites was investigated.The composites with 3 wt% OMMT had the best wall thickness consistency.The gas barrier property of the composite is improved by 43.9% over virgin PA6.The impact strength of the composite is improved by 133.8% over virgin PA6.Insights for the development of processing methods for plastic packaging inserts. [ABSTRACT FROM AUTHOR]

Rotational molded foam is known as one of the most popular types of polymeric foams due to its unique properties. Hence, the production of rotational molded foam samples has been well‐addressed in the foam literature, and several researchers have tried to produce these samples using different approaches. However, there is no comprehensive research that investigates the structural properties of nanocomposite foam samples produced by a two‐step process of rotational molding and batch foaming. Therefore, the effect of nanoclay and foam processing parameters on the structural properties of the samples produced by this method was investigated in this study. For this purpose, the Box–Behnken design of response surface methodology was used. The results revealed that the foaming temperature was the most effective parameter on cell density and expansion ratio. Also, the foaming time was reported as the most effective parameter on the cell size. Then, the response variables were subjected to single‐ and multi‐objective optimizations. Finally, the addition of 1.2 wt% of nanoclay, the foaming temperature of 141°C, and the foaming time of 85 s were introduced as the most optimal conditions to simultaneously achieve maximum cell density and expansion ratio and minimum cell size in the rotational molded nanocomposite foam samples. [ABSTRACT FROM AUTHOR]

In this study, using the method of probabilistic deterministic planning (PDP), the optimum design parameters of a standard polyethylene tank used worldwide for transporting liquid mineral fertilizers (LMF) were determined. By the finite element method, the effect of the density of liquid mineral fertilizer, tank wall thickness and four motion modes (braking, acceleration, jump and landing) on the strength of standard polyethylene tanks was studied. According to the results of the study, the five most informative areas in the tank design were identified, for which the values of maximum stresses (σmax) were obtained: filler neck, pockets, walls, tapin points and wall transition to the tank roof. As the LMF density increases, σmax in the tank increases linearly. Increasing the tank wall thickness by 1.5 times reduces the maximum stresses by 30 to 50 %. It was found that motion mode has a significant effect on the stress-strain state of a standard tank. The “heaviest” mode for a standard tank is “braking”. The “acceleration” motion mode causes σmax of no more than 60 % of the “braking” mode values. The “lightest” mode is “landing”, in which σmax is no more than 28 % relative to “braking”. Based on the PDP method, equations were derived for calculating maximum stresses depending on LMF density, wall thickness and motion mode of the tank. Nomograms were built that make it possible to quickly determine the wall thickness of a standard tank without calculations, depending on external factors. The results of the study can be used in practice when designing safe and durable tanks for transporting liquid mineral fertilizers. [ABSTRACT FROM AUTHOR]

With the increasing demand for lightweight construction machinery, it is of great significance to study non-metallic materials that can replace steel plates to make hydraulic oil tanks (HOTs). To explore the feasibility of making HOTs with three materials—cross-linked polyethylene (XLPE), polypropylene (PP), and nylon (PA)—this paper takes 28 L and 115 L volumes commonly used in construction machinery, such as forklifts and loaders, as the design volume and obtains non-metal HOT products of good forming quality by regulating the process parameters. Based on the test methods and evaluation bases of the fuel tank in the national standard, the normal-temperature pressure test, high-temperature pressure test, and low-temperature impact test are designed according to the working conditions of the HOTs. Finally, the non-metallic HOT products are tested. The results show that the rotational molding of XLPE material is the easiest, and products of all sizes can be molded, but the mechanical properties and thermal stability of the products are poor. The low-temperature impact resistance of PP products is poor. PA material can be used to create small HOTs, and the product performance is excellent. This research serves as a valuable reference for the non-metallic and lightweight design of HOTs. [ABSTRACT FROM AUTHOR]

There are multiple factors that contribute to the warpage problems where molten part is distorted during solidification in rotational molding. A novel warpage simulation model is developed accounting for the effect of various process parameters like crystallinity change, temperature‐dependent polymer properties, and cooling rate. The polymer material properties were readily not available; they were constructed from literature data with adaptation to the process condition and their significance on simulation results is discussed in detail. A systematic detailed simulation analysis of warpage in box part was done and results were compared with experimental values published in literature. The warpage magnitude under seven different cooling methods are presented. It was found that externally water cooled parts exhibited maximum warpage which is also corroborated by literature data while the parts cooled by water on either sides of the part show reduction in warpage. The warpage simulation results show an agreement with deviation ranging from 1.2% to 69% with experimental values. Highlights: A novel thermal expansion coefficient approach was adopted for the first time to develop warpage simulation of rotationally moulded parts.Inclusion of temperature‐dependent thermo‐mechanical properties of polymer in the simulation model.The cooling rate is directly proportional to the warpage in the parts.Validating warpage simulation results for seven different cooling methods with experimental measurements.Maximum warpage is seen where the highest temperature difference exists between part and mould. [ABSTRACT FROM AUTHOR]

Rotational Molding is defined as a plastic manufacturing method wherein a benefit of stress-free plastic product is accessible. Linear Low-Density Polyethylene (LLDPE) has consistently been on elevated priority as base material for rotomolded product. Notwithstanding, LLDPE requires to annotate its strength as needed in couple of applications. Added substances or fillers can fill the void to upgrade the mechanical properties. A legitimate choice of additives to convey a suitable required mechanical property in rotationally molded product has consistently been on research mode. Composites prepared using synthetic fibers have always proved to sustain better mechanical properties in the end product. Multi-criteria dynamic procedures were utilized to address the selection of a suitable additive considering various attributes from an enormous number of options. In the current context of investigation, multi criteria decision making techniques (MCDM) like TOPSIS and MOORA strategies were made as a wellspring of help to select the feasible synthetic fiber that can be opted for blending with the base resin for rotational molding process. MCDM techniques has been observed to be fruitful in solving the real time problems for selection of materials. The findings thus attained are relatively reasonable and can be used in the design process of the roto-molded product for blending with the resin. Polyester from synthetic fibers was classified as the top-ranking material based on the characteristics used in deciphering these methods. [ABSTRACT FROM AUTHOR]

The evolution of foam in unpressurized melt processing techniques, such as rotational molding, is different from high‐pressure processes like injection foam molding, making comparisons difficult. This has driven the need for a dedicated technique for studying these systems. A unique test procedure was developed to capture and characterize foam evolution in test tubes under unpressurized conditions. A validation study found the procedure to be reliable, producing repeatable samples (height average (AVG) 39.69 ± 1.70 mm and density AVG 0.319 ± 0.012 g/cm3) and delivering comparable results to samples produced using the industrial rotational foam molding process. A study examined the effect of polymer particle size on the foam structures produced. Finer (>90 μm <106 μm) polymer powders produced more desirable structures, achieving 38.6% lower foam density and 43.8% taller peak foam height than coarser powders (>425 μm < 500 μm). Cycle times were much shorter (~15 min) in comparison with the industrial rotational molding process (>40 min) and required smaller amounts of materials, making it useful for rapid characterization. Future work is planned to apply the new procedure to investigate the effects of material and processing conditions on the foam structures produced under unpressurized conditions. Highlights: Evaluation of existing unpressurized foam characterization methods.Rapid test procedure developed to characterize unpressurized foam evolution.Variability study of foam structures produced using the new procedure.Effect of rotational molding polymer powder and considerations for foaming.Results validated with industrial unpressurized rotationally molded samples. [ABSTRACT FROM AUTHOR]

In this study, high density polyethylene (HDPE) was combined with dicumyl peroxide (DCP) to produce crosslinked parts via rotational molding. The effect of DCP content (0.1–2.5 phr) on the crosslinking degree was investigated to determine its effect on the chemical, mechanical, physical, and thermal properties of HDPE. The gel content and crosslink density was found to increase with DCP content. These trends led to a reduction in the degree of crystallinity, melting, and crystallization temperature. Thermogravimetric analysis (TGA) showed that crosslinked HDPE (xHDPE) has higher thermal stability than the neat matrix in both air and nitrogen atmosphere. In addition, a direct relationship was observed between improved thermal resistance and higher impact strength. Finally, relationships between the tensile properties of xHDPE and the degree of crystallinity were observed, which were all controlled by the level of crosslinking. These results have the potential to advance the manufacturing of high performance materials suitable for a wide range of applications such as automotive parts, agricultural products, chemical storage tanks, large waste containers, and fuel tanks in general. [ABSTRACT FROM AUTHOR]

In this study, a desktop‐class dual‐axis rotational molder was employed to mold PA6 products. Notably, the morphology of the plastic powder during the rotational molding process was examined through visualization techniques. The research also aimed to delineate the causes of wall thickness variation in the products, while proposing a process method to enhance the uniformity of wall thickness. The implementation of a two‐stage mold temperature setting method for the ends of the mold improved wall thickness uniformity of the products. Furthermore, the interrelationships between crystallinity, tensile strength, and impact strength of the products were explored by comparing different cooling rate conditions. Increasing the cooling rate resulted in a decrease in both crystallinity and tensile strength, while concurrently boosting the impact strength of the products. Highlights: A desktop‐class, two‐axis rotational molding equipment is designed.A method for visualizing the rotational molding process is conducted.Mold temperature and rotational speed affect product wall thickness.Two‐stage mold temperature improves wall thickness uniformity.Mold cooling rate affects the tensile and impact strength of the product. [ABSTRACT FROM AUTHOR]

This paper focuses on the use of castor oil plant (Ricinus communis) as filler in rotomolded parts using polyethylene (PE) and polylactic acid (PLA) as polymer matrixes. The vegetable shredded material was used in 5 and 10% weight following a dry blending procedure and then rotomolded to obtain cube test parts. This material was characterized to determine its chemical composition, thermal stability, and structure. The NaOH-treated material shows reduced hemicellulose content and higher thermal stability. Obtained composite materials were characterized in terms of mechanical (tensile, flexural, and impact) and thermal properties, morphology, and bio-disintegration behavior. The use of Ricinus as filler in rotomolded PE composite decreases, in general terms, mechanical properties of neat PE, while no significant changes in thermal or bio-disintegration properties are found. On the contrary, PLA composites show higher tensile strength and similar Young's modulus than the matrix, although with reduced flexural and impact properties. Alkali-treated Ricinus material produces parts with higher porosity and thus, lower mechanical properties than composites with untreated material. Finally, the incorporation of this vegetal material modifies to a great extent the thermal properties of the PLA matrix. The bio-disintegration rate increases due to the use of fibers, probably because of the higher moisture absorption of composites. [ABSTRACT FROM AUTHOR]

The notion of renewable energy has become deeply ingrained in the world, captivating an increasing number of researchers and industry professionals who invest substantial resources to advance the development of more efficient systems. While large-scale wind turbine blades currently reach lengths exceeding 50 m and are typically manufactured as single entities, this study focuses on the design and evaluation of a blade profile tailored specifically for small turbines. The blades were manufactured using rotational molding, employing various groups of polymers including thermosets and thermoplastics. To enhance their mechanical performance, foams were incorporated into the polyurethane and polyethylene blades. The suitable blade by evaluating various formulations and foams was identified by mechanical analysis. Aerodynamic analysis was conducted across different ranges of wind speeds and pitch angles. The results indicate that the power coefficient (Cp) closely approaches 0.5. [ABSTRACT FROM AUTHOR]

This study focuses on the heating stage of the rotational molding process. When the mold wall reaches the tacky temperature, free flowing powder starts to adhere, melt, and sinter. In this work, a new modeling strategy is proposed. Compared with the models found in the literature, the model combines the use of a tacky temperature for the adherence of powder, changing boundary conditions, and thermophysical properties as function of temperature and the degree of sintering. The changing boundary conditions are introduced to take into account both wall to air and wall to powder contact. The calculation of the temperature evolution is done by applying the thermal finite difference principle to elements with a fixed polymer mass. The modeling of a uniaxial rotating cylinder is chosen as a case study. The validation is done for an amorphous polycarbonate resin. The performance of the model is evaluated not only by the comparison of temperature‐time data as is the case in most literature, but also by the decrease in free flowing powder weight as function of time, visual data from an in‐mold looking camera, and through thickness analysis of the molded pieces at various moments in the heating process. [ABSTRACT FROM AUTHOR]

The linear low density polyethylene (LLDPE) products made by rotational molding (RM) usually involve two main problems of poor dimensional stability and insufficient mechanical properties. Although the decline in thermal expansion coefficient and rise in mechanical strength can be attained by filling with inorganic particles, the melt fluidity of LLDPE, which is of great importance for RM, would be significantly reduced. In this study, a combination of crosslinker low‐temperature blending and partial chemical crosslinking strategy is employed to enhance the dimensional stability and mechanical properties of LLDPE without sacrificing the melt fluidity. The structure–property relationships in the crosslinked specimens are analyzed based on X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and dielectric spectrometry. The results show that our simple, low‐cost and universal strategy not only contributes to a better dimensional stability and significantly improved mechanical properties, but also endow the samples with promising processability and thermal stability. [ABSTRACT FROM AUTHOR]

Numerous efforts have been made to study the mechanical characterization of rotomolded products; however, as rotomolded products are used in critical applications it is necessary to know the effect of process parameters on mechanical and fracture behavior of rotomolded products. In the present study, LLDPE samples with different peak internal air temperature (PIAT) values were tested for bulge behavior, burst behavior, creep behavior and fatigue behavior on the experimental test set up to minimize the defects obtained during the process. The tank used for the experimental analysis is of 30 liter volume capacity which is like the tank installed on vehicle running in actual condition. For PIAT values 180 and 190 °C, the temporary deformation and permanent deformation lie within the acceptance criteria of less than 60 mm for temporary deformation and less than 25 mm for permanent deformation, but the samples failed during creep test. The samples prepared at 195 °C PIAT values passed in all physical testing performed. The average defect occurrence after taking the corrective measures during rotational molding process dropped to 50% compared to earlier stages. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article provides a comprehensive review of the recent literature on various natural fiber and inorganic filler-based polymer composites used in rotational molding (RM). The RM has grown in prominence in various essential applications in recent years. Different industries are working to create lighter components, especially in the automobile and aerospace industries, to improve fuel efficiency and reduce costs. Polymer matrix composites are lightweight, recyclable, corrosion-resistant, and cost-effective. Nonetheless, they are likewise limited in terms of strength, to overcome the polymer's obvious limitations natural fibers and inorganic particle fillers are often added to polymer composites in RM to improve their stiffness and strength and expand their uses. This necessitates a comprehensive study of the various materials available for rotational molding and their influence on the mechanical properties of composites. The variety of materials used in rotational molding is examined and recent advancements are highlighted in the first section. The second section of the discussion focuses on various materials used in rotational molding, their properties, and their advantages and disadvantages. The third section of the paper is dedicated to examining the relationship between the molecular weight of the material and the resulting crystallinity and mechanical properties of blended composites. The fourth section, which comes next, is about mixing natural fibers and inorganic filler with the base resin and their effect on the mechanical properties of a roto-molded product and also discusses the effect of fillers on the flow, void, and viscosity. The final section of the paper discusses several factors that can affect the properties of composites, including the particle size of natural and inorganic fillers, the heating and cooling of the mold, aging and degradation, and the rheology of the composite material. Past literature depicts that the mechanical properties of composite increase when the particle size gets smaller for both natural filler and inorganic particulate filler. This literature review has led to the following conclusion: to develop highly efficient particulate composites that can be greatly aided by careful selection of the base resin, additives, and parameter characterization. [ABSTRACT FROM AUTHOR]

Tanks made of three different brands of rotational polyethylene (DOW, ELTEX, and M350) with three degrees of sintering (normal sintering (NS), incomplete sintering (ICS), and thermally degraded sintering (TDS)) and three thicknesses (7.5 mm, 8.5 mm, and 9.5 mm) were explored. It was found that the thickness of the walls of the tanks did not have a statistically significant effect on the parameters of the ultrasonic signal (USS). An increase in temperature caused a decrease in the USS parameters. According to the temperature coefficient of stability, the ELTEX brand of plastic can be distinguished (from DOW and M350). The ICS degree of the sintering of the tanks was revealed from a significantly lower amplitude of the bottom signal, compared with NS and TDS degree samples. By analyzing the amplitude of the third harmonic of the ultrasonic signal (β), three degrees of the sintering of containers NS, ICS, and TDS were revealed (with an accuracy of about 95%). Equations β = f(T, PIAT) were derived for each brand of rotational polyethylene (PE), and two-factor nomograms were constructed. Based on the results of this research, a method for the ultrasonic quality control of polyethylene tanks manufactured using rotational molding was developed. [ABSTRACT FROM AUTHOR]

In this paper, the possibility of obtaining uniaxially rotomolded composite parts was discussed. The used matrix was bio-based low-density polyethylene (bioLDPE) filled with black tea waste (BTW) to prevent the thermooxidation of samples during processing. In rotational molding technology, the material is held at an elevated temperature in a molten state for a relatively long time, which can result in polymer oxidation. The Fourier transform infrared spectroscopy (FTIR) shows that adding 10 wt% of black tea waste has not led to the formation of carbonyl compounds in polyethylene, and adding 5 wt% and above prevents the appearance of the C–O stretching band connected with degradation of LDPE. The rheological analysis proved the stabilizing effect of black tea waste on the polyethylene matrix. The same temperature conditions of rotational molding did not change the chemical composition of black tea but slightly influenced the antioxidant activity of methanolic extracts; the detected changes suggest degradation is a color change, and the total color change parameter (ΔE) is 25. The oxidation level of unstabilized polyethylene measured using the carbonyl index exceeds 1.5 and gradually decreases with the addition of BTW. The BTW filler did not influence the melting properties of bioLDPE; the melting and crystallization temperature remained stable. The addition of BTW deteriorates the composite mechanical performance, including Young modulus and tensile strength, compared to the neat bioLDPE. [ABSTRACT FROM AUTHOR]

The rotational molding technology is becoming more popular and even outstanding some of the conventional polymer processing technologies. The production of polymer composites via this technology is still not described thoroughly. This work discusses the possibilities of obtaining polyethylene composites reinforced with short basalt fibers. Two methods of incorporating the fibrous fillers, dry-blending and through preliminary extrusion, are concerned. The application of the extrusion step to mixed polymer matrix with basalt fiber results in better distribution of basalt fibers than the direct dry blending polymer powder with fiber in the mold. The basalt fibers from rotomolded samples prepared from melt mixed plastic powder significantly reduced their length, leading to a substantial limitation in their reinforcing effect on the polymer matrix. The possible reinforcing effect was evaluated in a mechanical test such as a tensile test and hardness. Optical microscopy helped in the investigation of the distribution of basalt fibers. Not only the physical structure of composites was examined, but also the chemical composition using the Fourier transform infrared spectroscopy. The spectroscopic analysis confirms a properly realized technological process without degradation caused by rotational molding or additional melt blending. The production of good-quality rotomolded composites reinforced with basalt fibers depends on the method of incorporating the fibrous filler. [ABSTRACT FROM AUTHOR]

An increased awareness of sustainability among the population leads, from an industrial point of view, to efforts to act more ecologically as well as to the aim for lower production costs and an increased efficiency. With this in mind, a new process has been developed for foaming without blowing agents in rotational molding. Process related air inclusions in the polymer melt are expanded to form the cell structure by means of vacuum application. In the presented study, the influence of different particle sizes as well as the arising potential of deploying microgranules in the otherwise powder-based process is investigated with regard to the resulting foam cells. The results confirm that particle size and form greatly influence the existence and size of air inclusions in the polymer melt. It could be proven that these differences, caused by the particle characteristics, propagate during the foaming process and lead to different cell morphologies in the resultant foam. Furthermore, it is indicated that qualitative predictions of the resulting cell dimensions can be made on the basis of bulk density measurements and the analysis of the sintering behaviour of the initial particles. [ABSTRACT FROM AUTHOR]

The rapid development of hydrogen fuel cells has been paralleled by increased demand for lightweight type IV hydrogen storage vessels with high hydrogen storage density, which raises the performance requirements of internal plastic liners. An appropriate manufacturing process is important to improve the quality of polymer liners. In this paper, DSC, WAXD, a universal testing machine and a differential pressure gas permeameter were used to investigate the effect of the cooling rate of the rotational molding polyamide 11 on the thermal, crystallization, mechanical and barrier properties. The cooling rate is formulated according to the cooling rate that can be achieved in actual production. The results suggest that two PA11 liner materials initially exhibited two-dimensional (circular) growth under non-isothermal crystallization conditions and shifted to one-dimensional space growth due to spherulite collision and crowding during the secondary crystallization stage. The slower the cooling process, the greater the crystallinity of the specimen. The increase in crystallinity significantly improved the barrier properties of the two PA11 liner materials, and the gas permeability coefficient was 2-3-fold higher than at low crystallinity. Moreover, the tensile strength, the tensile modulus, the flexural strength, and the flexural modulus increased, and the elongation at break decreased as the crystallinity increased. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rotational molding allows for obtaining hollow parts with good aesthetics and properties, having as main drawbacks the lack of pressure and the long cycle times, which limit the range of materials. Different fillers have been introduced in rotomolding to obtain composite materials assessed. This review has shown that glass fibers or particles are the most common material among them, although carbon fibers or clays have also been studied. In general terms, 10% loadings provide an increase in mechanical properties; higher loadings usually lead to a decrease in processability or final properties. When the filler consists of a micro- or nano-material, such as clay or graphene, lower loadings are proposed, generally not exceeding 3%. The use of fillers of an inorganic nature to obtain composites has not been as explored as the incorporation of lignocellulosic materials and even less if referring to waste materials or side streams from industrial processes. So, there is a broad field for assessing the processing and properties of rotomolded composites containing inorganic waste materials, including the study of the relationship between the ratio of filler/reinforcement and the final properties and also their preprocessing (dry blending vs. melting compounding). [ABSTRACT FROM AUTHOR]

This paper assesses the modifications in the properties of rotomolded polyethylene (PE) and polylactic acid (PLA) composites obtained with 5 and 10% giant reed fibers, mainly focusing on the alterations due to a bio-disintegration process. Thermal properties (melting temperature and crystallinity degree), morphology (via optical and scanning electron microscopy), and chemical changes (by Fourier Transformed Infrared spectroscopy) were studied. Composites with untreated and NaOH-treated fibers were obtained, finding that this treatment does not improve the mechanical performance of composites due to increased porosity. The introduction of natural fibers into a PE matrix does not significantly modify the thermal and bio-disintegration properties of the rotomolded material. Regarding mechanical properties, PE-composites show increased tensile modulus and reduced impact and tensile strength than the matrix. On the other hand, PLA composites show lower impact and flexural strength than neat PLA, remaining the rest of the mechanical properties unchanged regardless of the fibers' addition. The incorporation of Arundo fibers modifies to a great extent the thermal and degradation behavior of the PLA matrix. [ABSTRACT FROM AUTHOR]

Composites suitable for rotational molding technology based on poly(ε-caprolactone) (PCL) and filled with hollow glass microspheres (HGM) or functionalized hollow glass microspheres (HGMf) were prepared via melt-compounding. The functionalization of glass microspheres was carried out by a silanization treatment in order to improve the compatibility between the inorganic particles and the polymer matrix and achieve a good dispersion of glass microspheres in the matrix and an enhanced filler–polymer adhesion. The crystallization behavior of materials was studied by DSC under isothermal and non-isothermal conditions and the nucleating effect of the glass microspheres was proven. In particular, the presence of silanized glass microspheres promoted faster crystallization rates and higher nucleation activity, which are enhanced by 75% and 50%, respectively, comparing neat PCL and the composite filled with 20 wt% HGMf. The crystalline and supermolecular structure of PCL and composites crystallized from the melt was evaluated by WAXD and SAXS, highlighting differences in terms of crystallinity index and structural parameters as a function of the adopted crystallization conditions. [ABSTRACT FROM AUTHOR]

Rotational foam molding has attracted more and more attention due to the inexpensive machines required, low residual stresses, and flexible design for special and high-value-added applications. However, it is a great challenge to control cell sizes and morphology because of its coalesce and collapse during prolonged heating or at different temperatures. A novel tailored polyethylene blend with a unique chain structure for rotational foam molding was creatively proposed and demonstrated, and the effects of crystallization temperature and viscosity–temperature sensitivity on foaming were also investigated. The polyethylene blends with few chain branches in the low-molecular-weight part and many chain branches in the high-molecular-weight part effectively improved the crystallization temperature and the viscosity–temperature sensitivity for better prevention of coalesce and collapse during the foam-shaping stage. [ABSTRACT FROM AUTHOR]

Rotational molding is a technology in which polymeric thin-walled products can be made. The newest descriptions of this technology concern the possibility of obtaining polymer composite materials. There are two main methods of incorporating fillers into a polymer matrix. Dry blending is based on mixing fillers with polymer powders before rotational molding by hand or using automatic mixers. In the melt compounding method, fillers are mixed with the polymer in the preliminary step by melt processing and then grinding or pulverization to obtain polymer powders for rotational molding. This work aimed to investigate the impact of the processing procedure on the structure and properties of biobased composites with expanded vermiculite. Produced rotomolded parts were examined using mechanical tests to assess changes in tensile, flexural, and impact properties. The most significant difference in mechanical properties was noted for samples with 10 wt% expanded vermiculite (EV). The elasticity modulus increases by almost 2 fold when the sample is prepared in a two-step process, the tensile strength is 4-fold higher, the flexural modulus is 3-fold higher, and the flexural strength is 5-fold higher. We also investigated thermomechanical properties in DMA measurement. The void volume content was also measured to control the quality of obtained parts. The porosity of dry blended samples containing more than 2 wt% EV is almost 2-fold higher. Other methods to control quality and structure were optical and scanning electron microscopy used for rotomolded parts and polymer powders. The investigations of rotomolded parts were supplemented with a complete description of used materials, including the particle size distributions of polymer powders and filler. Analysis of the thermal properties and chemical structure was also performed despite all the mechanical tests. The emerging conclusions from the research clearly show that the two-step process allows for achieving a more beneficial mechanical performance of the composites made of the biobased polymer in rotational molding technology. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, the effect of plasma treatment of polyethylene powder and glass fibers on the adhesion between polyethylene and glass fibers in composites prepared by rotational molding was studied. In contrast to other processing techniques, such as injection molding, the rotational molding process operates at atmospheric pressure, and no pressure is added to ensure mechanical interlocking. This makes reinforcing the rotomolded product very difficult. Therefore, the formation of chemical bonds is necessary for strong adhesion. Different combinations of untreated polyethylene (UT.PE), plasma-treated polyethylene (PT.PE), untreated and plasma-treated glass fibers were manually mixed and processed by rotational molding. The resulting composites were cut and tested to demonstrate the effect of the treatment on the adhesion between the composite components and on the mechanical properties of the final composites. The results showed that the treatment of both powder and fiber improved the adhesion between the matrix and fibers, thus improving the mechanical properties of the resulting composites compared to those of pure polyethylene samples and composites prepared using untreated components. The tensile strength, tensile modulus, and flexural modulus of the composites prepared using 10-min treated powder with 20 wt% of 40-min treated fibers improved by 20%, 82%, and 98%, respectively, compared to the pure polyethylene samples. [ABSTRACT FROM AUTHOR]

The lack of suitable destinations for plastics materials can be a global environmental problem. The alternative use of materials for sustainable construction encourages the standardization of waste and promotes effective social, environmental and economic gains at the local level and ensures savings and income for communities. The aim of this paper is the development, manufacture, and characterization of PP and HDPE recycled polyolefin blocks as masonry components in civil construction. These blocks were manufactured by the rotational molding process. Besides this, the mechanical, physical, impact and flammability properties of the blocks were studied. In conclusion, HDPE showed better behavior than PP in tests realized. [ABSTRACT FROM AUTHOR]

To investigate the impact of zinc oxide/titanium dioxide nanoparticles on the characteristics of high‐density polyethylene, researchers used the rotational molding technique to produce polymeric nanocomposites. The nanocomposites' morphological, mechanical, optical, as well as biological characteristics, were studied using a range of characterizations. SEM analysis revealed a uniform morphology of ZnO and TiO2 nanoparticles in the polymer matrix, with 80–120 nanometers middle particle dimensions. The existence of ZnO with hexagonal wurtzite form as well as TiO2 with rutile phase was verified by XRD and XRF. Corresponded to the pure polymer, the HDPE‐ZnO/TiO2 nanocomposites' flexural modulus and tensile strength increased, but elongation at break reduced, according to mechanical characterization. UV–visible spectroscopy revealed that the HDPE‐ ZnO/TiO2 nanocomposites showed UV light absorption at wavelengths ranging from 250 to 390 nm. According to antibacterial tests and contact angle measurements, adding metal oxide NPs to HDPE improved hydrophilicity and antibacterial activity. [ABSTRACT FROM AUTHOR]

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Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rotational molding is an idiosyncratic plastic manufacturing technique that provides a comparatively stress free end product. The base resin extensively preferred for rotomolding is Linear Low Density Polyethylene (LLDPE). However, when compared to common engineering materials, pure LLDPE embarks poor mechanical properties targeting few critical applications. Usage of glass fibres as an additive is well known to the researchers in such criteria. But its industrially processed dust is yet to be investigated for rotational molding process. Thus, in the current context, rotationally molded LLDPE based products are investigated wherein glass fibres dust (GFD) are embedded into thermoplastic resin to examine the variation in strength and stiffness of end product. According to preliminary processing tests conducted, approximately 20% and below of LLPDE/GFD composites was observed to provide better fluidity as a prerequisite for rotomoldability. Hence, an experimental study was performed to benchmark the presence of 10%, 15%, 20% and 25% GFD when mixed with LLDPE for rotomolded product. When treating LLDPE/GFD at distinct weight ratio, the rate of heat transfer was also evaluated using the mold, oven, and internal air temperature. The composite's crystallinity was investigated using DSC analysis to assess the concentration of GFD incorporated in LLDPE. Scanning electron microscopy was furthermore utilized to display the underlying mechanisms of LLDPE/GFD ratios. The present work successfully signifies an increase in an overall performance due to the impact of GFD over unreinforced LLDPE. Therefore, it is hypothesized that till 20% GFD addition in the LLDPE matrix is expected to lead a rise in mechanical properties, thus potentially approaching towards retaining the requisite degree of design freedom of rotational molding process. [ABSTRACT FROM AUTHOR]

This work focuses on the development of a numerical mold filling simulation for the rotational molding process. In the rotational molding process, a dry fiber preform is placed in a mold and impregnated with a thermoset matrix under rotation. Additionally, metallic load introduction elements can be inserted into the mold and joined with co-curing or form-fit, resulting in hybrid drive shafts or tie rods. The numerical model can be used to simulate the impregnation of the preform. Based on the resin transfer molding process, an OpenFOAM solver is extended for the rotational molding process. Permeability, kinetic and curing models are selected and adapted to the materials used. A wireless measurement solution with a capacitive sensor is developed to validate the model. Comparisons between measurements and numerically calculated impregnation times to reach the capacitive sensor with the matrix show good quality of the developed model. The average deviation between calculated result and measured mean values in the experiment is 43.8% the maximum deviation is 65.8%. The model can therefore be used to predict the impregnation progress and the curing state. [ABSTRACT FROM AUTHOR]

Rotational moulding of plastics is rapidly developing in the world today. However, with this method of processing, "microbubbles" can occur in the walls of products, considerably impairing their quality. In this paper, the method of ultrasonic testing (UST) is applied to assess the quality of plastic products. With the help of an echo method at a working frequency of 2.5 MHz, samples of various degrees of quality were analyzed. It has been revealed that the propagation speed of an ultrasonic signal does not depend on the degree of product quality and is m/s. It has been found that the larger the surface roughness parameter Rz of the products (from 2.5 to 20 μm), the smaller the amplitude of the bottom signal becomes. An underheated sample is determined by the values of parameter from –6.0 to –15.0 MHz. A reference sample was established ( g/cm3) for calibrating the flaw detector; for this sample dB at an operating frequency of 2.5 MHz. The relationship between the density/heating of products and the amplitude of the bottom signal has been revealed. The possibility of detecting internal defects of products by ultrasonic inspection has been proven. A new method is proposed for identifying suitable articles in production using which it is possible to determine the degree of product quality. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Rotational molding is a technique used to process plastic materials that provide the advantage of obtaining a stress-free end product. While linear low-density polyethylene (LLDPE) is largely preferred for this method, LLDPE is mixed with different additives in order to obtain adequate strength for some critical applications. In contemplation to obtain a sound product, proper mixing of base resin and additives while sustaining rotomoldability is desirable. In the present study, processibility analysis of LLDPE/glass fiber is investigated. Researchers are familiar with the use of glass fibers as an additive in such criteria. However, the rotational molding process has yet to be studied using its industrially processed dust. In particular, the residue of industrially obtained glass fiber (GF) as a waste is mixed with LLDPE in the different weight ratio of 10% to 50%, with 5% increase subsequently. Fourier transform infrared spectroscopy is a technique performed to obtain the optimum percentage range where the result infer the dominant peaks of LLDPE and glass fiber assuring the needed blending. Melt flow index test was carried out to assess the rotomoldability of LLDPE/GF fiber in terms of fluidity. Furthermore, the current research examines the effects on the shear modulus and crystallinity of LLDPE/GF blends based on the rheological and DSC analysis, respectively. In conclusion, the experimental results suggest that 20% LLDPE/GF blend is an optimal percentage for the rotational molding process to achieve requisite processibility. [ABSTRACT FROM AUTHOR]

Experience of structure development, manufacture, and testing of a pneumatic pressure shell accumulator with a volume of 25 dm3 is presented. A binder composition for "cold" hardening based on ÉD-20 epoxy resin and Étal-23X cycloaliphatic amine is developed. In terms of rheological and physicomechanical properties the binder proposed is suitable for manufacturing shells by a "wet" winding method with low energy consumption for hardening. [ABSTRACT FROM AUTHOR]

Rotational molding is a plastic manufacturing process that is used to produce seamless, one-piece, and hollow parts by rotating a mold subjected to heat and then cooling it. The aim of this study is to investigate the tensile properties of produced polymeric nanocomposite samples by rotational molding. Linear low-density polyethylene was considered as the polymeric matrix, and nanoclay was added at various weight percentages of 0, 1, and 2 as reinforcement. The effects of weight percentages of nanoclay and processing conditions including rotational speed and processing temperature are investigated on the tensile properties of nanocomposite samples based on the design of experiments according to the L9 orthogonal array of Taguchi approach. Scanning electron microscopy tests were performed on the nanocomposite samples in order to study the possible agglomeration regions of the nanoclays in the polymeric matrix. The results indicate that the processing temperature is the most effective parameter on the tensile strength and Young's modulus of nanocomposite samples. Tensile strength and Young's modulus were increased by 21% and 33%, respectively, by increasing the processing temperature. Also, the rotational speed is found to be the second effective parameter on the tensile properties. [ABSTRACT FROM AUTHOR]

In this work, rotational molding was used to produce parts based on a blend of linear low‐density polyethylene (LLDPE) and polyamide 6 (PA6). In particular, the concentration of PA6 (0, 10, 20, and 30% vol) with and without a compatibilizer (Surlyn 9020) was investigated via two methods: dry blending in a high‐shear mixer and melt compounding in a twin‐screw extruder followed by pulverization. To determine the efficiency of the rotomolding process, similar parts were produced via compression molding. For rotational molding, dry ice (solid CO2) was used to create an inert atmosphere in the mold and the processing conditions were followed by the mold internal air temperature traces. From the samples produced, thermal, morphological, and mechanical properties were measured. The results showed that the rotomolded parts of the melt blended compounds generated smaller and better dispersed PA6 particles in the LLDPE matrix. This finer morphology led to improved mechanical properties, especially when the compatibilizer was present. But the latter was found to be more effective on the compression‐molded samples. [ABSTRACT FROM AUTHOR]

The importance of manufacturing of hydrogen fuel tanks due to the application of hydrogen fuels in clean and recyclable energy is one of the most important issues of substituting the petroleum fuels. They consist of two main parts: Plastic liner, as a barrier escape of hydrogen and Carbon Fiber Reinforced Polymer (CFRP) layer to strengthen tanks. The liner plastic could be manufactured by rotational molding or blow molding. In rotational molding, the metallic boss embedded into the mold directly and stick on the polymer before wrapping step. However, in blow molding, the metallic boss is welded to liner polymer. By comparing these two methods, rotational molding demonstrates better feedback because of its capability in assembling boss and liner part, and also manufacturing the piece simultaneously, without the defect arising from welding. Moreover, improvement in the adhesion capacity of polymer to metal could be obtained by effective surface treatments. Therefore, good knowledge of adhesion concept could be useful in these regards. In this work, the possible treatments on Aluminum (metal) and medium density polyethylene (liner) which could be applied in rotational molding is proposed and the adhesion behavior of them has been compared. These surface treatments are anodizing, flaming, sandblasting with different average size of sand particles, and coating with polyethylene grafted (PEG) (CEA patent n°FR3035173). Despite of the mechanical test results, it was found that the sandblasting treatment (with higher roughness value) combined with PEG coating performed higher adhesion at the interface of metal/polymer in compare with other possible methods in rotational molding. Microstructures of these different surface treatments confirmed the obtained mechanical results. [ABSTRACT FROM AUTHOR]

The growing interest in research and development of eco-friendlier materials makes attractive the use of bio-based and biodegradable polymers such as polylactic acid (PLA). However, the higher cost of PLA compared to conventional polymers limits its applications. Moreover, raw materials for rotational molding must be in a powder form, which further increases their cost. So, the main objective of this study was to use agave fibers to produce lower-cost PLA based rotomolded biocomposites (BC) without compromising its bio-sourced origin and to compare with a standard rotomolding resin: linear medium density polyethylene (LMDPE). To improve the fiber-matrix interface, a chemical surface treatment of the fibers with glycidyl methacrylate grafted polylactic acid (GMA-g-PLA) in solution was evaluated. The results showed that a better biocomposites' morphology was obtained, especially with the fibers treated twice. The surface treatment was also shown to substantially improve the flexural and tensile properties of treated fiber biocomposites at higher fiber content (25% wt.) compared to those with untreated fiber. The surface treatment also led to a substantial reduction of the biocomposites porosity and water absorption. Overall, the samples were shown to have better mechanical properties than neat LMDPE while being eco-friendlier due to their bio-nature. [ABSTRACT FROM AUTHOR]

In recent years, foams have experienced a major economic uprise, not least due to their lightweight construction potential. In this article, a new process variation is presented, which enables the generation of foamed structures in rotational molding by the utilization of vacuum. The novel method is based on entrapped air in the melt as an intrinsic physical blowing agent. By applying negative pressure in the cooling or solidification phase, the air bubbles expand. The crystallization freezes the existing conditions and thus forms the foamed structure. The investigations presented consider influences by different pressures as well as the temperature at which the vacuum is applied. The results with polyethylene show that by varying the pressure as well as the application temperature of the vacuum, components with different densities and cell characteristics result. The resulting foamed components excel by an improved stiffness per unit weight ratio. [ABSTRACT FROM AUTHOR]

Rotational Molding is a unique polymer processing technique that gives an advantage of having stress free end product. Majorly, Linear Low Density Polyethylene (LLDPE) is preferred as a base resin for rotomolding. However, incorporation of additives becomes necessary to improve mechanical properties and viscoelasticity as incumbent for few applications. The present research makes an attempt to investigate the effect of coir fiber on rotationally moldable LLDPE. Based on preliminary processing experiments, 10% or less Coir in its powder form when mixed with LLDPE was found to account a better flow ability as a prerequisite for roto moldability. Hence, the effect of 3%, 5%, 7% and 10% Coir mixed with LLDPE was experimented for the roto molded product to determine the mechanical properties, viz. tensile, flexural, hardness and impact strength. Also, the rate of heat transfer was evaluated subjected to the data recorded for mold, oven and internal air temperature when processing LLDPE/Coir considering different weight percentages. Crystallinity of the blend was examined based on DSC analysis for the distinguished percentage of coir incorporated in LLDPE. The experimental results depicted an improvised mechanical properties by 7% or less fiber addition, and beyond that, the properties were found to be regressed. The present work successfully engulfed Coir with LLDPE, producing a uniform distribution along the sides of the mold without applying any external pressure. Therefore, fiber integration in the rotomolding process is believed to be possible thus preserving homogeneous randomly distributed fiber dispersion. [ABSTRACT FROM AUTHOR]

The present review elaborates about the complexity being associated with the intensification of Rotational Molding process. It is a technique used in the manufacturing of hollow stress-free plastic products. In recent years, as rotational molding process has gained popularity in various critical applications, a detailed study on this technique needs to be analyzed deliberately. For this reason, an extensive review of rotational molding process has been effectuated in this paper, which is mainly categorized into four different sections, namely, materials, additives, processibility and process parameters. The paper analyses exhaustively the dynamic quality of processibility, parametric analysis and industrial applications of roto-molded product documented by different researchers. First two section focuses mainly on mixing distinguished materials and additives with the base resin in order to achieve optimal mechanical properties in a roto-molded product. Consecutively, third section explains the fusion of powder and its characterization in terms of roto moldability. The last part is a detailed analysis of parametric study affecting rotational molding process. It can be concluded from the literature review that a suitable selection of base resin, additives, processibility analysis and parameter characterization can execute a vital role to augment advancements in rotational molding process. [ABSTRACT FROM AUTHOR]

Rotational molding or rotomolding is a powder processing technique used for the manufacturing of hollow plastic products. The present work investigates the moldability of long bamboo fiber as the reinforcement for linear low-density polyethylene (LLDPE) matrix. The temperature of the mold, oven and internal air temperature of the mold has been recorded to study the heat transfer rate while processing composites with different weight percentage. Mechanical properties were found to be improved by 5% fiber addition, and beyond that, the properties were reverted. Morphological characterization was done to analyze the interfacial properties of fiber and matrix. The present work successfully incorporated long bamboo fibers with LLDPE powders and uniformly distributed these fibers along the sides of the mold without applying any external pressure. Thus, it is concluded that fiber incorporation is possible in the rotomolding process and homogenous randomly oriented fiber dispersion can also be achieved by the rotational molding process. [ABSTRACT FROM AUTHOR]

Rotomolding is a versatile process used in the manufacture of thermoplastic polymeric materials to produce large hollow plastic parts. The aim of this review article was to discuss the rotomolding process and show the properties of the polyethylene composite and rotomolded lignocellulosic fibers, which are processed for prolonged periods under temperature. The main process parameters studied are the shaft speed of the equipment, molding temperature, polymer particle size, polymer melt flow index, and amount of material, which must be well controlled to achieve a non-degraded product with homogeneous thickness and no porosity. Rotomolded composites containing sisal, pine, coir, banana, flax, and maple wood fibers, among others, have been evaluated primarily for their mechanical (impact, flexural, and tensile strength) and morphological properties. The type, content, and treatment of lignocellulosic fillers are the most widely studied variables in polyethylene-based rotomolded composites. Fiber content was the variable that most influenced mechanical properties, particularly impact strength and hardness due to the voids formed by the hydrodynamic volume between the polymer matrix and lignocellulosic filler. Chemical treatment of the fiber by mercerization with NaOH made it more hydrophobic and the addition of maleic anhydride-grafted polyethylene as a coupling agent improved the interfacial adhesion between the non-polar polymer matrix and polar filler. However, the best mechanical property results were obtained with the use of maleic anhydride-grafted polyethylene. [ABSTRACT FROM AUTHOR]