G. Dogossy

8898339500

Publications - 23

Automotive Application of Chemically Foamed rPET

András Kovács V. A. Szabó Sándor K. Jakab Tamara Zsuzsanna Böcz G. Dogossy

Publication Name: Polymers

Publication Date: 2025-05-01

Volume: 17

Issue: 9

Page Range: Unknown

Description:

This study investigated the automotive applicability of parts produced from a newly developed foamed recycled polyethylene terephthalate (rPET). The injection molded part contained a combination of both endothermic and exothermic foaming agents and phosphorus (Exolit OP 1240) (OP)- and melamine polyphosphate (MPP)-based flame retardant agents. The parts were produced using a breathing mold technique to achieve a suitable level of foaming. The aim was to produce lighter parts made of recycled material that also complied with the fire safety automotive industry standards. Computer tomographic scans revealed the foam structure formed successfully, which contributed to an improved strength-to-weight ratio. The scans further showcased that larger cells tended to form in the thicker areas within the part, while smaller cells generally formed in the thinner areas. Finite element simulations showed that the large cell formation in the thicker parts had no effect on the part’s load bearing property, and there were not stress concentration points after the boundary conditions were defined. The sample produced from the material was determined to be a possible replacement of small-sized automotive components.

Open Access: Yes

DOI: 10.3390/polym17091251

Use of Hybrid Flame Retardants in Chemically Foamed rPET Blends

András Kovács V. A. Szabó Sándor K. Jakab Tamara Zsuzsanna Böcz G. Dogossy

Publication Name: Crystals

Publication Date: 2025-01-01

Volume: 15

Issue: 1

Page Range: Unknown

Description:

The foamed structure of recycled polyethylene-terephthalate (rPET) is a promising solution for industrial applications; however, the remedy for its inherent melt-dripping property is still a challenging topic. In our research, we were able to improve the flame retardancy of the endothermic–exothermic hybrid rPET foam by adding a different mixture of flame retardants to the formula. Three different kinds of halogen-free flame retardant agents were used: ammonium polyphosphate-based Exolit AP 422 (AP), organic aluminum phosphate in the form of Exolit OP 1240 (OP), and Budit 342 containing melamine polyphosphate (MPP). The hybrid flame retardant mixture, by combining the swelling and charring mechanism, increased the flame retardancy of the samples. The sample made with 15 phr OP and 5 phr MPP displayed outstanding performance, where five samples were capable of self-extinguishing in 5 s, while only slightly decreasing the tensile and flexural strength properties and simultaneously increasing the Young and flexural modulus compared to the reference sample. The addition of MPP reduced the porosity in many cases, while preventing cell coalescence. Our results prove that the hybrid flame retardant agent frameworks efficiently increase the flame retardancy of rPET foams, facilitating their application in industrial sectors such as the aerospace, packaging, renewable energy, and automotive industries to realize sustainability goals. The utilization of halogen-free flame retardants is beneficial for better air quality, reducing toxic gas and smoke emissions.

Open Access: Yes

DOI: 10.3390/cryst15010080

Endothermic–Exothermic Hybrid Foaming of Recycled PET Blends

Gusztáv Fekete V. A. Szabó G. Dogossy

Publication Name: Journal of Composites Science

Publication Date: 2024-10-01

Volume: 8

Issue: 10

Page Range: Unknown

Description:

Over the past decades, the use of polyethylene terephthalate (PET) has seen significant growth, particularly in the packaging industry. However, its long decomposition time poses serious environmental challenges. The aim of this research was to develop a process for the foaming of large quantities of recycled PET (rPET) using endothermic and exothermic foaming agents. Various formulations with different ratios of endothermic and exothermic foaming agents were prepared, as well as their mixtures. The study found that the endothermic–exothermic hybrid foaming process resulted in a finer cell-size distribution and enhanced mechanical properties, making the foams highly suitable for widespread applications. The results support the potential use of exothermic foaming agents as nucleating agents in a hybrid foaming system. In particular, the ratio of 3% endothermic and 1% exothermic foaming agents proved optimal in terms of achieving a balance between porosity and mechanical strength, thereby enabling broad industrial applicability.

Open Access: Yes

DOI: 10.3390/jcs8100383

Preface: First Sustainable Mobility and Transportation Symposium (SMTS 2024) †

Ferenc Szauter G. Dogossy

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

No description provided

Open Access: Yes

DOI: 10.3390/engproc2024079097

Foam Injection Molding of Poly(Lactic Acid) with Azodicarbonamide-Based Chemical Blowing Agent †

I. Fekete László Lendvai Sándor K. Jakab G. Dogossy

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

In this study, poly(lactic acid) (PLA)-based biopolymer foams were prepared through injection molding using the high-pressure foam injection molding method, also referred to as “breathing mold” technique, with the addition of various amounts (0, 1, 2, and 4 wt.%) of azodicarbonamide-based chemical blowing agent (CBA). The prepared samples were analyzed for their macrostructure using computed tomography (CT) while the mechanical properties were determined by flexural and Charpy impact tests. CT analysis revealed a finer foam cell structure and decreasing shell thickness with increasing CBA content. Regarding the mechanical properties, the specific flexural strength and flexural modulus of PLA were improved as a result of foaming; however, this improvement came at the cost of a slight deterioration in impact strength.

Open Access: Yes

DOI: 10.3390/engproc2024079044

Development of Injection Moulded Electromagnetic Pulse Shielded Polymer Cover

F. Ronkay G. Dogossy

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 186-193

Description:

Technology for an electromagnetic pulse shielded injection moulded product was developed, using in-mould metal mesh and a 3D printed spacer made of the same type of acrylonitrile-butadiene-styrene as the injection moulded polymer. The functional and mechanical properties of the manufactured flat and dumbbel specimens were tested. The metal mesh increased the stiffness of the plastic, decreased its Charpy impact strength, and did not significantly affect its tensile strength. Computed tomography scans confirmed that delamination and microcracking occur during the failure due to different elongation of the plastic and metal. The attenuation at 1 GHz was 16-19 dB, depending on the metal mesh used. The shielding properties were affected by the fact that the high pressure at the mould filling during the injection moulding process distorted the geometry of the metal mesh.

Open Access: Yes

DOI: 10.3233/ATDE240544

Resistance to Tensile Stress and Foam Structure Formation in Chemically Foamed rPET Blends †

V. A. Szabó Gábor Böcz G. Dogossy

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

This research investigates the correlation between tensile strength, tensile strain, and porosity in chemically foamed recycled poly(ethylene-terephthalate) (rPET) samples. Tensile strength and strain were measured on non-foamed samples to predict the porosity of the foamed samples. Utilizing various flame retardants and additives, we analyzed their impact on mechanical properties and structures. However, neither tensile strength nor strain demonstrated a reliable correlation with the resulting porosity. Strain values did not consistently predict porosity, indicating the significant role of additive types and concentrations.

Open Access: Yes

DOI: 10.3390/engproc2024079070

Valorization of Waste Wood Flour and Rice Husk in Poly(Lactic Acid)-Based Hybrid Biocomposites

Amar Patnaik László Lendvai Tej Singh Maria Omastova G. Dogossy

Publication Name: Journal of Polymers and the Environment

Publication Date: 2023-02-01

Volume: 31

Issue: 2

Page Range: 541-551

Description:

This study explores the possibility of developing a new class of hybrid particulate-filled biocomposites using wood flour and rice husk wastes as environmentally friendly additives to poly(lactic acid) (PLA) as matrix material. Samples were prepared with fillers of different concentrations (0, 2.5, 5, 7.5 and 10 wt %), while the ratio of wood flour and rice husk was fixed at 1:1 in all cases. The preparation of biocomposites was performed through extrusion using a twin-screw extruder. Subsequently, they were formed into specimens by injection molding. Mechanical, thermal, thermomechanical, and morphological properties were examined. The addition of natural waste particles resulted in a remarkable improvement both in tensile and flexural modulus; however at a cost of impact strength and tensile strength. Meanwhile, flexural stress at conventional strain values were barely affected by the presence of wood flour and rice husk. The SEM images confirmed that there is a limited interfacial adhesion between the components, which supports the results obtained during mechanical tests. Both the differential scanning calorimetry (DSC) and the dynamic mechanical analysis indicated that the glass transition temperature of PLA was not affected by the incorporation of filler particles; however, the crystalline structure was gradually altered with increasing filler loading according to the DSC. Additionally, the particles were observed acting as nucleating agents, thereby increasing the overall crystallinity of PLA.

Open Access: Yes

DOI: 10.1007/s10924-022-02633-9

Effect of Injection Molding Parameters on the Chemical Foaming of Acrylonitrile Butadiene Styrene (ABS) Using Breathing Mold Technology

Sándor K. Jakab G. Dogossy

Publication Name: Chemical Engineering Transactions

Publication Date: 2023-01-01

Volume: 107

Issue: Unknown

Page Range: 247-252

Description:

Manufacturers have to adapt very quickly to the accelerating world and use specialized machines for production to meet the demands. This also means that those machines are not used as often as their mass-producing counterparts and sometimes become obsolete. In the case of foaming with injection molding, a complicated system has to be built around the machine and has to be structured in a specific way, which is not always cost-efficient. In this paper, two methods of chemical foaming of Acrylonitrile Butadiene Styrene (ABS) were performed on a regular injection molding machine. Chemical Blowing Agent (CBA) and Expandable Microsphere (EMS) were used with breathing mold technology. Injection molding parameters were modified, and specimens were produced for mechanical and morphological examinations. Properly selected parameters for foaming play an important role in retaining the mechanical strength of the product. With low switch-over volume and using the core-back method, it is possible to foam ABS using a Chemical Blowing Agent.

Open Access: Yes

DOI: 10.3303/CET23107042

Experimental Investigation and Applicability of Multi-Stage Simulations in the Case of a Thick-Walled Injection-Moulded Composite

F. Ronkay Tamás Morauszki G. Dogossy

Publication Name: Applied Sciences Switzerland

Publication Date: 2022-09-01

Volume: 12

Issue: 17

Page Range: Unknown

Description:

The structure and mechanical properties of an injection-moulded short glass fibre (GF)-reinforced polymer composite were analysed through simulation methods. Fibre orientation, which evolves during the production of a thick-walled automotive part, was determined with an injection moulding simulation. Next, using the material model for the injected product, the force that resulted from the given deformation was determined with finite element software. To validate the simulation results, the examined products were manufactured with 30% reinforced GF, and then measurements were carried out. The validation of the fibre orientation tensor was achieved with optical microscope images, while the validation of the finite element, which analysed the flexural tests, was carried out through a comparison of flexural rigidity. The aim of the project was to verify the reliability of multi-stage finite element software. According to the results, in the case of a thick-walled GF-reinforced product, it was demonstrated that the integration of a different finite element software could be used reliably.

Open Access: Yes

DOI: 10.3390/app12178415

Optimization on physicomechanical and wear properties of wood waste filled poly(lactic acid) biocomposites using integrated entropy-simple additive weighting approach

Gusztáv Fekete László Lendvai Shiv Ranjan Kumar Punyasloka Pattnaik Tej Singh G. Dogossy

Publication Name: South African Journal of Chemical Engineering

Publication Date: 2022-07-01

Volume: 41

Issue: Unknown

Page Range: 193-202

Description:

The present research work develops an evaluation method based on the hybrid entropy-simple additive weighting approach to select the best biocomposite material based on several potentially conflicting criteria. Poly(lactic acid) (PLA) biocomposites with varying proportions of wood waste (0, 2.5, 5, 7.5, and 10 by weight) was developed and evaluated for physical, mechanical, and sliding wear properties. The biocomposite containing 10 wt.% wood waste exhibited the lowest density (1.183 g/cm3) and highest modulus properties (tensile modulus = 2.97 GPa; compressive modulus = 3.46 GPa; and flexural modulus = 4.03 GPa). The bare PLA exhibited the highest strength properties (tensile strength = 57.96 MPa; compressive strength = 105.67 MPa; impact strength = 15.25 kJ/m2), whereas flexural strength (100.43 MPa) was the highest for 5 wt.% wood waste filled biocomposite. The wear of PLA decreased with 2.5 wt.% wood waste incorporated and increased with further addition of wood waste. The experimental results revealed a high compositional dependence with no discernible trend. As a result, prioritizing biocomposites' performance to choose the best from various biocomposite alternatives becomes tough. Therefore, a multi-criteria decision-making process based on a hybrid entropy-simple additive weighting approach was applied to find the optimal biocomposite by taking the experimental results as the selection criterion. The results show that the 2.5 wt.% wood waste added PLA biocomposite proved to be the best solution with optimal physical, mechanical, and wear properties. The validation with other decision-making models supports the robustness of the proposed approach in that the 2.5 wt.% wood waste added PLA biocomposite is the most dominating. This study contributes by providing preferences for the selection criteria and assessing the best alternative from the available PLA biocomposites.

Open Access: Yes

DOI: 10.1016/j.sajce.2022.06.008

Optimal Design of Wood/Rice Husk-waste-Filled PLA Biocomposites Using Integrated CRITIC–MABAC-Based Decision-Making Algorithm

Amit Aherwar László Lendvai Punyasloka Pattnaik Lalit Ranakoti Tej Singh G. Dogossy

Publication Name: Polymers

Publication Date: 2022-07-01

Volume: 14

Issue: 13

Page Range: Unknown

Description:

Based on the criteria importance through inter-criteria correlation (CRITIC) and the multi-attributive border approximation area comparison (MABAC), a decision-making algorithm was developed to select the optimal biocomposite material according to several conflicting attributes. Poly(lactic acid) (PLA)-based binary biocomposites containing wood waste and ternary biocompos-ites containing wood waste/rice husk with an overall additive content of 0, 2.5, 5, 7.5 and 10 wt.% were manufactured and evaluated for physicomechanical and wear properties. For the algorithm, the following performance attributes were considered through testing: the evaluated physical (density, water absorption), mechanical (tensile, flexural, compressive and impact) and sliding wear proper-ties. The water absorption and strength properties were found to be the highest for unfilled PLA, while modulus performance remained the highest for 10 wt.% rice husk/wood-waste-added PLA biocomposites. The density of PLA biocomposites increased as rice husk increased, while it decreased as wood waste increased. The lowest and highest density values were recorded for 10 wt.% wood waste and rice husk/wood-waste-containing PLA biocomposites, respectively. The lowest wear was exhibited by the 5 wt.% rice husk/wood-waste-loaded PLA biocomposite. The experimental results were composition dependent and devoid of any discernible trend. Consequently, prioritizing the performance of PLA biocomposites to choose the best one among a collection of alternatives became challenging. Therefore, a decision-making algorithm, called CRITIC–MABAC, was used to select the optimal composition. The importance of attributes was determined by assigning weight using the CRITIC method, while the MABAC method was employed to assess the complete ranking of the biocomposites. The results achieved from the hybrid CRITIC–MABAC approach demonstrated that the 7.5 wt.% wood-waste-added PLA biocomposite exhibited the optimal physicomechanical and wear properties.

Open Access: Yes

DOI: 10.3390/polym14132603

Thermal and Sliding Wear Properties of Wood Waste-Filled Poly(Lactic Acid) Biocomposites

Amar Patnaik László Lendvai Lalit Ranakoti Tej Singh G. Dogossy

Publication Name: Polymers

Publication Date: 2022-06-01

Volume: 14

Issue: 11

Page Range: Unknown

Description:

In our study, the effects of wood waste content (0, 2.5, 5, 7.5, and 10 wt.%) on thermal and dry sliding wear properties of poly(lactic acid) (PLA) biocomposites were investigated. The wear of developed composites was examined under dry contact conditions at different operating parameters, such as sliding velocity (1 m/s, 2 m/s, and 3 m/s) and normal load (10 N, 20 N, and 30 N) at a fixed sliding distance of 2000 m. Thermogravimetric analysis demonstrated that the inclusion of wood waste decreased the thermal stability of PLA biocomposites. The experimental results indicate that wear of biocomposites increased with a rise in load and sliding velocity. There was a 26–38% reduction in wear compared with pure PLA when 2.5 wt.% wood waste was added to composites. The Taguchi method with L25 orthogonal array was used to analyze the sliding wear behavior of the developed biocomposites. The results indicate that the wood waste content with 46.82% contribution emerged as the most crucial parameter affecting the wear of PLA biocomposites. The worn surfaces of the biocomposites were examined by scanning electron microscopy to study possible wear mechanisms and correlate them with the obtained wear results.

Open Access: Yes

DOI: 10.3390/polym14112230

Physical, mechanical, and thermal properties of Dalbergia sissoo wood waste-filled poly(lactic acid) composites

Gusztáv Fekete László Lendvai Tej Singh G. Dogossy

Publication Name: Polymer Composites

Publication Date: 2021-09-01

Volume: 42

Issue: 9

Page Range: 4380-4389

Description:

The present work intended to investigate the effect of Dalbergia sissoo wood waste on physical, mechanical, and thermal properties of poly(lactic acid) (PLA)-based composites. The composite specimens, containing wood waste (2.5%, 5%, 7.5%, and 10% by weight) mixed with PLA granules, were prepared by melt compounding. It was found that increased wood waste content resulted in higher modulus, porosity, and water absorption with decreased density, tensile strength, impact strength, and stress at break. Nevertheless, the flexural strength values of the composites were similar to unfilled PLA and they remained almost constant irrespective of the wood waste content. Differential scanning calorimetry analysis revealed that the presence of wood waste content increased the glass transition and cold crystallization temperature of the PLA composites. Moreover, the fractured surfaces of the composites were examined with a scanning electron microscope to study the possible failure mechanisms. The conducted investigations demonstrated that low-cost wood waste-based composites can be used as an environmentally and economically attractive substitute for lightweight applications.

Open Access: Yes

DOI: 10.1002/pc.26155

Utilization of Waste Marble Dust in Poly(Lactic Acid)-Based Biocomposites: Mechanical, Thermal and Wear Properties

Amar Patnaik Gusztáv Fekete László Lendvai Tej Singh G. Dogossy

Publication Name: Journal of Polymers and the Environment

Publication Date: 2021-09-01

Volume: 29

Issue: 9

Page Range: 2952-2963

Description:

The aim of this present work was to study the applicability of waste marble dust (MD) in poly(lactic acid) (PLA)-based composites. Samples containing up to 20 wt% waste MD were prepared via melt blending. The attention was focused on the investigation of mechanical, morphological, thermal properties and the wear resistance of the PLA/MD composites. Regarding the mechanical properties, both the tensile and the flexural modulus improved remarkably, however, a slight loss was observed in strength and deformability. The impact toughness showed an increasing tendency up to 10 wt% MD loading, which was followed by a marginal decrease at higher concentration. With respect to the sliding wear rate, the composite with the highest MD content showed the best wear resistance. According to the DSC measurements, the MD hampered the chain mobility of PLA, thereby reducing the crystalline ratio. Overall, composites with improved properties were developed, while the reuse of waste MD is expected to reduce the production costs as well.

Open Access: Yes

DOI: 10.1007/s10924-021-02091-9

Speckle pattern optimization for DIC technologies

Szabolcs Szalai G. Dogossy

Publication Name: Acta Technica Jaurinensis

Publication Date: 2021-01-01

Volume: 14

Issue: 3

Page Range: 228-243

Description:

This paper contains the relation between speckle pattern and Digital Image Correlation (DIC). The most important advance in experimental mechanics has been DIC since the strain gage. The deformation (strain) of an object can be visualized by DIC. Among all scientific fields, the DIC Technologies have seen a dynamic increase. The relationship between the paint and the sample-as the patterns mediate the deformation to the cameras-has been the most important technological issue. In this article the method developed for the detection of isolated particles in alloys is used to characterize the spots, which help the best speckle pattern has determined.

Open Access: Yes

DOI: 10.14513/actatechjaur.00573

Antibacterial and anti-inflammatory activities of Cassia fistula fungal broth-capped silver nanoparticles

Gusztáv Fekete László Lendvai Kumari Jyoti Devender Arora Tej Singh G. Dogossy

Publication Name: Materials Technology

Publication Date: 2021-01-01

Volume: 36

Issue: 14

Page Range: 883-893

Description:

The growing need for sustainable technologies has attracted considerable interest in the synthesis of ecofriendly materials. This paper reports the anti-inflammatory and antibacterial activities of sustainable silver nanoparticles (AgNPs) fabricated using endophytic fungus extracted from a medicinal plant, Cassia fistula. Fourier transform-infrared and UV-visible were used for AgNPs characterisation. X-ray diffraction, scanning electron microscope, energy dispersive X-ray analysis, atomic force microscope (AFM), transmission electron microscope and dynamic light scattering analysis revealed that the biosynthesised AgNPs were within the size of ~4–54 nm. The synthesised AgNPs displayed considerable antibacterial activity against Staphylococcus aureus, Escherichia coli and Klebsiella pneumonia bacterial strains. Additionally, synthesised AgNPs showed significant anti-inflammatory potential.

Open Access: Yes

DOI: 10.1080/10667857.2020.1802841

Flame retardancy of recycled PET foam

V. A. Szabó G. Dogossy

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2020-08-25

Volume: 903

Issue: 1

Page Range: Unknown

Description:

Although significant marketing efforts have been made in recent years to reduce polymer use, the number of plastic bottles being discarded is increasing worldwide. The global environmental-socio-economic problem posed by polyethylene terephthalate (PET) bottles can only be solved by expanding large-scale recycling opportunities, while reducing the use of pure raw materials. In this article on the large quantities product of PET was upcycled with chemical foaming. During the experiments 2 m% chain extender and 4 m% chemical blowing agent and different amount of brominated flame retardant was used. The invested materials were examined with standard mechanical tests, scanning electron microscopy and UL-94 standard flammability test. After the investigation it was found that the crystallized blue PET bottle re-granulate can be used forming a flame retardant closed cell foam structure.

Open Access: Yes

DOI: 10.1088/1757-899X/903/1/012048

Investigation of flame retardant RPET foam

V. A. Szabó G. Dogossy

Publication Name: Periodica Polytechnica Mechanical Engineering

Publication Date: 2020-01-01

Volume: 64

Issue: 1

Page Range: 81-87

Description:

The use of plastics in the food and the packaging industries continuously is increasing. In these areas of use the product's life cycle is short, therefore it quickly turns into waste. The polyethylene terephthalate (PET) - the material that is used as beverage containers - are the material with the greatest environmental load. The physical recycling of PET bottles in large quantities was the research goal. During the work with the help of chemical foaming a closed cell structural foam from PET bottle was produced. The research was carried out with upcycling using chain extender and impact modifier additives. For industrial use a bromine-based flame retardant was used and excellent flame retardancy was achieved. Based on the results obtained, the material previously managed as waste, with the appropriate treatment can be involved into the manufacturing of new products.

Open Access: Yes

DOI: 10.3311/PPme.14556

Structure and properties of closed-cell foam prepared from rPET

V. A. Szabó G. Dogossy

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2018-10-18

Volume: 426

Issue: 1

Page Range: Unknown

Description:

Nowadays, in the field of packaging technology, one-way polymer packaging materials are increasingly used. Food and packaging industry uses the most, the life cycle of which becomes short, they become waste very quick. Also included are light weight bottles of polyethylene terephthalate (PET). Large amounts of waste can be handled with multiple options. The worst is their dumping on dump sites, as these materials do not compost. Their thermal recycling is more favorable due to their high calorific value, but a real cycle can only be achieved by their physical recycling. However, during the multiple re-purposing, PET's mechanical and processing properties are reduced. In our research, chemical foaming has been investigated, resulting in a smaller weight, better specific property, and fully reusable product. During our investigations, the structure and mechanical properties of recycled PET (rPET) specimens manufactured with different composition, chain and foam additives were analyzed.

Open Access: Yes

DOI: 10.1088/1757-899X/426/1/012043

The effect of mold temperature on chemical foaming of injection molded recycled polyethylene-terephthalate

F. Ronkay Bela Molnar G. Dogossy

Publication Name: Thermochimica Acta

Publication Date: 2017-05-10

Volume: 651

Issue: Unknown

Page Range: 65-72

Description:

Foam injection molded samples were produced from recycled polyethylene-terephthalate using endothermic and exothermic foaming agents at different mold temperatures. The foam structure was analyzed by computer tomography and optical microscopy. The morphological properties of samples were analyzed by differential scanning calorimetry, using the three-phase model. Viscosities of the melts were changed during processing by endothermic and exothermic foaming agents, and as a result different foam structures were formed. Relationships between mold temperature and porosity were found. Morphologies of the samples made with different foaming agents were different, also due to the different cooling rates caused by the endothermic and exothermic foaming reactions.

Open Access: Yes

DOI: 10.1016/j.tca.2017.02.013

Investigation of mixing processes of polymer composites

F. Ronkay E. Sági G. Dogossy

Publication Name: Materials Science Forum

Publication Date: 2013-01-01

Volume: 729

Issue: Unknown

Page Range: 332-337

Description:

Three ultrahigh molecular weight polyethylene (UHMWPE) composites of differing composition, reinforced with multiwalled carbon nanotubes (MWCNT) were prepared. The homogeneous distribution of MWCNT has been attempted by two dry blending methods and one melt-mixing process. The efficiency of the various methods was characterized by their effects on the quasi-static and dynamic physical properties of the composites. In the case of composites manufactured by ball milling the effects of various adhesion promoter additives (compatibilizers) has also been studied by analyzing the tensile, flexural, Charpy impact and wear properties of the composites. © (2013) Trans Tech Publications, Switzerland.

Open Access: Yes

DOI: 10.4028/www.scientific.net/MSF.729.332

Thermoplastic starch composites reinforced by agricultural by-products: Properties, biodegradability, and application

T. Czigany G. Dogossy

Publication Name: Journal of Reinforced Plastics and Composites

Publication Date: 2011-11-01

Volume: 30

Issue: 21

Page Range: 1819-1825

Description:

This article focuses on the development of starch-based biodegradable polymer composites reinforced by agricultural byproducts. Maize hull and sugarcane bagasse were used as reinforcements in maize starch, which was plasticized by glycerol and maltitol. Compounds with different compositions were produced by compounding in a twin screw extruder. The mechanical (tensile-, three point bending-, and Charpy-impact) properties and shrinkage were determined on injection-molded specimens and compared with those of commercial HDPE. The mechanical properties of thermoplastic starch increased with the addition of both maze hull and sugarcane bagasse, but only the latter ensured comparable results with reference HDPE. This was traced to differences in the interfacial adhesion between filler and matrix as observed by scanning electron microscopy. Distance spacers for pizza boxes, usually made from HDPE, were injection molded from these biodegradable composites and subjected biodegradation in soil. The related results indicated that this biodegradable spacer is a good and environmentally benign alternative for the HDPE counterpart.

Open Access: Yes

DOI: 10.1177/0731684411429728