scholarly journals The Effects of Chain-Extending Cross-Linkers on the Mechanical and Thermal Properties of Poly(butylene adipate terephthalate)/Poly(lactic acid) Blown Films

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3092
Author(s):  
Juliana V. C. Azevedo ◽  
Esther Ramakers-van Dorp ◽  
Berenika Hausnerova ◽  
Bernhard Möginger
Keyword(s):  
Mechanical Performance ◽  
Synergetic Effect ◽  
Mechanical Analysis ◽  
Polymer Chains ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Film Blowing ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Seal Strength

This study investigates the effects of four multifunctional chain-extending cross-linkers (CECL) on the processability, mechanical performance, and structure of polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) blends produced using film blowing technology. The newly developed reference compound (M·VERA® B5029) and the CECL modified blends are characterized with respect to the initial properties and the corresponding properties after aging at 50 °C for 1 and 2 months. The tensile strength, seal strength, and melt volume rate (MVR) are markedly changed after thermal aging, whereas the storage modulus, elongation at the break, and tear resistance remain constant. The degradation of the polymer chains and crosslinking with increased and decreased MVR, respectively, is examined thoroughly with differential scanning calorimetry (DSC), with the results indicating that the CECL-modified blends do not generally endure thermo-oxidation over time. Further, DSC measurements of 25 µm and 100 µm films reveal that film blowing pronouncedly changes the structures of the compounds. These findings are also confirmed by dynamic mechanical analysis, with the conclusion that tris(2,4-di-tert-butylphenyl)phosphite barely affects the glass transition temperature, while with the other changes in CECL are seen. Cross-linking is found for aromatic polycarbodiimide and poly(4,4-dicyclohexylmethanecarbodiimide) CECL after melting of granules and films, although overall the most synergetic effect of the CECL is shown by 1,3-phenylenebisoxazoline.

scholarly journals The Influence of Sub-Zero Conditions on the Mechanical Properties of Polylactide-Based Composites

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5789
Author(s):  
Olga Mysiukiewicz ◽  
Mateusz Barczewski ◽  
Arkadiusz Kloziński
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Mechanical Performance ◽  
Mechanical Analysis ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Linseed Cake ◽  
Static Mechanical

Polylactide-based composites filled with waste fillers due to their sustainability are a subject of many current papers, in which their structural, mechanical, and thermal properties are evaluated. However, few studies focus on their behavior in low temperatures. In this paper, dynamic and quasi-static mechanical properties of polylactide-based composites filled with 10 wt% of linseed cake (a by-product of mechanical oil extraction from linseed) were evaluated at room temperature and at −40 °C by means of dynamic mechanical analysis (DMA), Charpy’s impact strength test and uniaxial tensile test. It was found that the effect of plasticization provided by the oil contained in the filler at room temperature is significantly reduced in sub-zero conditions due to solidification of the oil around −18 °C, as it was shown by differential scanning calorimetry (DSC) and DMA, but the overall mechanical performance of the polylactide-based composites was sufficient to enable their use in low-temperature applications.

scholarly journals EFFECT OF POLYMER CHAIN MODIFICATIONS ON ELASTOMER PROPERTIES

2019 ◽  
Vol 92 (1) ◽  
pp. 69-89 ◽  
Author(s):  
Katarzyna S. Bandzierz ◽  
Louis A. E. M. Reuvekamp ◽  
Jerzy Dryzek ◽  
Wilma K. Dierkes ◽  
Anke Blume ◽  
...  
Keyword(s):  
Polymer Chain ◽  
Crosslink Density ◽  
Mechanical Performance ◽  
Transition Process ◽  
Mechanical Analysis ◽  
Polymer Chains ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Scanning Calorimetry ◽  
Tetramethylthiuram Disulfide

ABSTRACT Considerable attention is paid to the influence of crosslink density and crosslink structures on the behavior of polymer chains and properties of elastomers. However, a very important parameter seems to be underestimated: the modifications to the polymer chains by curatives, formed by sulfur and fragments of accelerators. We draw attention to this important contribution to performance of spatial networks. The emulsion styrene–butadiene rubber samples, cured with tetramethylthiuram disulfide and sulfur (TMTD/S8) and zinc dialkyl dithiophosphate with sulfur (ZDT/S8), were studied. They were characterized in detail in terms of crosslink density and crosslink structures. Microscale techniques were used to obtain information about the behavior of the polymer chains: positron annihilation lifetime spectroscopy (PALS) to study the free volume structure and differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) to monitor the glass transition process. Properties such as static mechanical performance and thermo-oxidative stability were also evaluated. All of the investigated characteristics were influenced by a combination of crosslink density, crosslink structures, and, to a large extent, by the modifications of the polymer chains. The effect of the modifications is dependent on the amount and the structure of the curatives' molecules. On the basis of the obtained results, the usefulness of the “phr” unit used for calculation of the curatives' amount has been queried. Furthermore, it has been demonstrated that DSC, DMA, and PALS techniques can provide evidence for the presence of the modifications on the polymer chain by curatives.

Poly(lactic acid) phase transitions in the presence of nano calcium carbonate: Opposing effect of nanofiller on static and dynamic measurements

2018 ◽  
Vol 32 (3) ◽  
pp. 312-327 ◽  
Author(s):  
Omid Yousefzade ◽  
Javad Jeddi ◽  
Elham Vazirinasab ◽  
Hamid Garmabi
Keyword(s):  
Lactic Acid ◽  
Glass Transition ◽  
Calcium Carbonate ◽  
Mechanical Analysis ◽  
Polymer Chains ◽  
Poly Lactic Acid ◽  
Modulated Dsc ◽  
Scanning Calorimetry ◽  
Chain Mobility ◽  
Dispersion State

The effect of stearic acid-coated nano calcium carbonate (NCC) on transitions and chain mobility of poly(lactic acid) (PLA) was investigated. Dispersion state of NCC in polymeric matrix was explored using scanning electron microscopy and surface tension component measurements. Trends of PLA transitional phenomena were investigated using the results of dynamical mechanical analysis (DMA) and differential scanning calorimetry (DSC) in the nanocomposite systems based on PLA and NCC. In addition, two types of crystal structures and decreasing the glass transition temperature were distinguished using temperature-modulated DSC (TMDSC). Higher melting points of polymer crystals were found in TMDSC experiments due to low and dynamic heating rate compared to the conventional DSC. Dynamics of polymer chains, affected by NCC, were quantified using cooperativity length, ξ α, and the number of relaxing structural units, Nα, in the glass transition region. NCC particles hindered the cooperative motion of polymer chains at glass transitions and crystallization in TMDSC measurements, whereas the DMA results indicated that NCC particles may act as lubricant and simplified chain mobility.

Thermal and Mechanical Properties of Highly-Filled Polybenzoxazine-Alumina Composites

2013 ◽  
Vol 545 ◽  
pp. 211-215 ◽  
Author(s):  
Jirawat Kajornchaiyakul ◽  
Chanchira Jubsilp ◽  
Sarawut Rimdusit
Keyword(s):  
Room Temperature ◽  
Alumina Particle ◽  
Mechanical Analysis ◽  
Interfacial Interaction ◽  
Alumina Content ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Alumina Composites

-Highly filled alumina polymer composites based on bisphenol-A/aniline benzoxazine resin (BA-a) were developed. The mechanical and thermal properties of these highly filled composites at various alumina filler contents from 0 to 85 % by weight were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The experimental results revealed that the storage modulus (E') at room temperature was increased from 5.93 GPa of the neat polybenzoxazine up to about 45.27 GPa of the composites with the maximum alumina content of 83 % by weight. The glass-transition temperatures (Tg) of the composites systematically increased with increasing the alumina filler contents. The Tgs of the obtained composites having alumina content ranging from 50 to 83 % by weight were found to be 178°C to 188°C, which higher that the Tg of the polybenzoxazine, i.e. 176°C implying substantial interfacial interaction between the alumina particle and the polybenzoxazine.

scholarly journals Biocomposites from Rice Straw Nanofibers: Morphology, Thermal and Mechanical Properties

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2138 ◽  
Author(s):  
José Carlos Alcántara ◽  
Israel González ◽  
M. Mercè Pareta ◽  
Fabiola Vilaseca
Keyword(s):  
Rice Straw ◽  
Mechanical Performance ◽  
Cellulose Nanofibers ◽  
Nucleating Agent ◽  
Mechanical Analysis ◽  
Nanocomposite Films ◽  
Chemical Extraction ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
The Matrix

Agricultural residues are major potential resources for biomass and for material production. In this work, rice straw residues were used to isolate cellulose nanofibers of different degree of oxidation. Firstly, bleached rice fibers were produced from the rice straw residues following chemical extraction and bleaching processes. Oxidation of rice fibers mediated by radical 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) at pH 10 was then applied to extract rice cellulose nanofibers, with diameters of 3–11 nm from morphological analysis. The strengthening capacity of rice nanofibers was tested by casting nanocomposite films with poly(vinyl alcohol) polymer. The same formulations with eucalyptus nanofibers were produced as comparison. Their thermal and mechanical performance was evaluated using thermogravimetry, differential scanning calorimetry, dynamic mechanical analysis and tensile testing. The glass transition of nanocomposites was shifted to higher temperatures with respect to the pure polymer by the addition of rice cellulose nanofibers. Rice nanofibers also acted as a nucleating agent for the polymer matrix. More flexible eucalyptus nanofibers did not show these two phenomena on the matrix. Instead, both types of nanofibers gave similar stiffening (as Young’s modulus) to the matrix reinforced up to 5 wt.%. The ultimate tensile strength of nanocomposite films revealed significant enhancing capacity for rice nanofibers, although this effect was somehow higher for eucalyptus nanofibers.

scholarly journals Micro and nanocomposites of polybutadienebased polyurethane liners with mineral fillers and nanoclay: thermal and mechanical properties

2017 ◽  
Vol 15 (1) ◽  
pp. 46-52 ◽  
Author(s):  
Pablo Ross ◽  
Germán Escobar ◽  
Guillermo Sevilla ◽  
Javier Quagliano
Keyword(s):  
Thermal Properties ◽  
Polymer Chains ◽  
Toluene Diisocyanate ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Elongation At Break ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mineral Fillers

AbstractMicro and nanocomposites of hydroxyl terminated polybutadiene (HTPB)-based polyurethanes (NPU) were obtained using five mineral fillers and Cloisite 20A nanoclay, respectively. Samples were prepared by the reaction of HTPB polyol and toluene diisocyanate (TDI), and the chain was further extended with glyceryl monoricinoleate to produce the final elastomeric polyurethanes. Mechanical and thermal properties were studied, showing that mineral fillers (20%w/w) significantly increased tensile strength, in particular nanoclay (at 5% w/w). When nanoclay-polymer dispersion was modified with a silane and hydantoin-bond promoter, elongation at break was significantly increased with respect to NPU with C20A. Thermal properties measured by differential scanning calorimetry (DSC) were not significantly affected in any case. The molecular structure of prepared micro and nanocomposites was confirmed by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. Interaction of fillers with polymer chains is discussed, considering the role of silanes in compatibilization of hydrophilic mineral fillers and hydrophobic polymer. The functionalization of nanoclay with HMDS silane was confirmed using FTIR. Microstructure of NPU with C20A nanoclay was confirmed by Atomic Force Microscopy (AFM).

scholarly journals Polydopamine-Coated Paraffin Microcapsules as a Multifunctional Filler Enhancing Thermal and Mechanical Performance of a Flexible Epoxy Resin

2020 ◽  
Vol 4 (4) ◽  
pp. 174
Author(s):  
Giulia Fredi ◽  
Cordelia Zimmerer ◽  
Christina Scheffler ◽  
Alessandro Pegoretti
Keyword(s):  
Phase Change ◽  
Storage Modulus ◽  
Mechanical Performance ◽  
Value Added ◽  
Mechanical Analysis ◽  
Scanning Calorimetry ◽  
Management Capability ◽  
Deposition Parameters ◽  
Potential Applications ◽  
Ep Matrix

This work focuses on flexible epoxy (EP) composites containing various amounts of neat and polydopamine (PDA)-coated paraffin microcapsules as a phase change material (PCM), which have potential applications as adhesives or flexible interfaces with thermal management capability for electronics or other high-value-added fields. After PDA modification, the surface of PDA-coated capsules (MC-PDA) becomes rough with a globular appearance, and the PDA layer enhances the adhesion with the surrounding epoxy matrix, as shown by scanning electron microscopy. PDA deposition parameters have been successfully tuned to obtain a PDA layer with a thickness of 53 ± 8 nm, and the total PDA mass in MC-PDA is only 2.2 wt %, considerably lower than previous results. This accounts for the fact that the phase change enthalpy of MC-PDA is only marginally lower than that of neat microcapsules (MC), being 221.1 J/g and 227.7 J/g, respectively. Differential scanning calorimetry shows that the phase change enthalpy of the prepared composites increases with the capsule content (up to 87.8 J/g) and that the enthalpy of the composites containing MC-PDA is comparable to that of the composites with MC. Dynamic mechanical analysis evidences a decreasing step in the storage modulus of all composites at the glass transition of the EP phase, but no additional signals are detected at the PCM melting. PCM addition positively contributes to the storage modulus both at room temperature and above Tg of the EP phase, and this effect is more evident for composites containing MC-PDA. As the capsule content increases, the mechanical properties of the host EP matrix also increase in terms of elastic modulus (up to +195%), tensile strength (up to +42%), Shore D hardness (up to +36%), and creep compliance (down to −54% at 60 min). These effects are more evident for composites containing MC-PDA due to the enhanced interfacial adhesion.

HIGH-IMPACT PP NANOCOMPOSITES: INFLUENCE OF CLAY CONTENT ON MECHANICAL AND THERMAL PROPERTIES

2013 ◽  
Vol 12 (06) ◽  
pp. 1350039
Author(s):  
L. G. FURLAN ◽  
RICARDO V. B. OLIVEIRA ◽  
ANDRÉIA C. E. MELLO ◽  
SUSANA A. LIBERMAN ◽  
MAURO A. S. OVIEDO ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Impact Strength ◽  
Flexural Modulus ◽  
Clay Content ◽  
Mechanical Analysis ◽  
High Impact ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Izod Impact

The preparation of high-impact polypropylene nanocomposites with different organo-montmorillonite (O-MMT) contents by means of meltprocessing was investigated. The nanocomposite properties were evaluated by transmission electron microscopy (TEM), flexural modulus, izod impact strength, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was noticed that the PP/O-MMT nanocomposites properties were affected by clay content. Exceptional improvements in impact strength were obtained (maximum of 185%) by the use of low O-MMT content. The results showed that higher enhancement on mechanical/thermal properties was obtained by 3 wt.% of O-MMT instead of higher quantities.

Mechanical and Thermal Properties of PLA Melt Blended with High Molecular Weight PEG Modified with Peroxide and Organo-Clay

2017 ◽  
Vol 751 ◽  
pp. 337-343 ◽  
Author(s):  
Chanchai Thongpina ◽  
Chaiwat Tippuwanan ◽  
Kwanchai Buaksuntear ◽  
Teerani Chuawittayawuta
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Mechanical Performance ◽  
Organic Peroxide ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Cloisite 30B

The thermal and mechanical properties of poly (lactic acid) blended with high molecular weight PEG, i.e. PEG1000 and PEG6000 were compared. The contents of PEG added were 10, 12.5 and 15 % by weight, with respect to PLA. The PLA/PEG blends were modified by addition of organic peroxide in order to induced crosslinking. Addition of organic modified montmorrillonite (Cloisite 30B, C30B) was also performed in order to modify mechanical performance of PLA/PEG blends. C30B was prepared via master batch in PLA. Morphology, crystallization, thermal stability and mechanical properties of the blends were investigated using SEM, DSC, TGA and universal testing macine, respectively. Morphology of cryogenic fracture surface showed smooth brittle surface. PEG1000 well plasticized PLA where as PEG6000 shows better thermal stability and mechanical properties. The presence of PEG induced PLA to perform cold crystallization. Tm in PLA was slightly changed whereas degree of crystallinity of PLA was improved by PEG but slightly decreased by peroxide. The thermal stability of PLA was enhanced with the addtion of PEG6000. The toughening of PLA was confirmed by the increment of elongation at break. The exfoliation of C30B was interfered by the crosslink PLA. Then tensile strength of PLA/PEG/C30B/Luperox101 was then suppressed. The optimum properties, in term of toughening and thermal stability, were found at PEG content of 10 % rather than 15% by weight, for both PEG1000 and PEG6000.

scholarly journals Bio-composites for Fused Filament Fabrication. Effects of Maleic Anhydride Grafting on Poly(Lactic Acid) and Microcellulose

2021 ◽  
Author(s):  
Daniele Rigotti ◽  
Luca Fambri ◽  
Alessandro Pegoretti
Keyword(s):  
Lactic Acid ◽  
Maleic Anhydride ◽  
Nucleating Agent ◽  
Mechanical Analysis ◽  
Poly Lactic Acid ◽  
Crystalline Cellulose ◽  
Fused Filament Fabrication ◽  
Scanning Calorimetry ◽  
Electron Microscopy Analysis ◽  
Reactive Mixing

Abstract Composite filaments consisting of poly(lactic acid) (PLA) and micro crystalline cellulose (MCC) were successfully used for additive manufacturing (AM) by fused filament fabrication (FFF). PLA and MCC bio-composites were obtained by direct mixing in a melt compounder; maleic anhydride (MAH) was also grafted onto PLA in reactive mixing stage to evaluate its effect on the final properties of the printed material. Filaments with various concentrations of MCC (up to a maximum content of 10 wt%) were produced with a single screw extruder and used to feed a commercial desktop FFF printer. Upon grafting of PLA with MAH, a more coherent interfacial morphology between PLA and MCC was detected by electron microscopy analysis. The thermal degradation of the PLA was unaffected by the presence of MCC and MAH. According to differential scanning calorimetry and dynamic mechanical analysis results, micro-cellulose acted as nucleating agent for PLA. In fact, the crystallization peak shifted towards lowers temperature and a synergistic effect when MCC was added to PLA grafted with MAH was observed possibly due to the increase of the chain mobility. Micro cellulose led to an increase in the stiffness of the material in both filaments and 3D printed specimen, however, a different fracture behavior was observed due to the peculiar structure of printed samples.

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