scholarly journals Melt Memory Effects in Poly(butylene succinate) Studied by Differential Fast Scanning Calorimetry

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2796
Author(s):  
Leire Sangroniz ◽  
Connie Ocando ◽  
Dario Cavallo ◽  
Alejandro J. Müller
Keyword(s):  
Memory Effect ◽  
Point Of View ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Butylene Succinate ◽  
Crystallinity Degree ◽  
Final Performance ◽  
Fast Scanning Calorimetry ◽  
History Of ◽  
Short Times

It is widely accepted that melt memory effect on polymer crystallization depends on thermal history of the material, however a systematic study of the different parameters involved in the process has been neglected, so far. In this work, poly(butylene succinate) has been selected to analyze the effect of short times and high cooling/heating rates that are relevant from an industrial point of view by taking advantage of fast scanning calorimetry (FSC). The FSC experiments reveal that the width of melt memory temperature range is reduced with the time spent at the self-nucleation temperature (Ts), since annealing of crystals occurs at higher temperatures. The effectiveness of self-nuclei to crystallize the sample is addressed by increasing the cooling rate from Ts temperature. The effect of previous standard state on melt memory is analyzed by (a) changing the cooling/heating rate and (b) applying successive self-nucleation and annealing (SSA) technique, observing a strong correlation between melting enthalpy or crystallinity degree and the extent of melt memory. The acquired knowledge can be extended to other semicrystalline polymers to control accurately the melt memory effect and therefore, the time needed to process the material and its final performance.

Analysis of the Thermo-Structural Behavior of Polyethylene Using Simultaneous DSC/XRD

1985 ◽  
Vol 29 ◽  
pp. 315-322 ◽  
Author(s):  
C. E. Crowder ◽  
S. Wood ◽  
B. G. Landes ◽  
R. A. Newman ◽  
J. A. Blazy ◽  
...  
Keyword(s):  
Thermal Conditions ◽  
Atmospheric Environment ◽  
Structural Behavior ◽  
X Ray Diffraction ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Past ◽  
Polymer Properties ◽  
History Of

Over the past 25 years, numerous studies of polymers utilizing both X-ray diffraction (XRD) and differential scanning calorimetry (DSC) have been reported in the literature. These studies have suffered because the two techniques must be performed on separate samples and under conditions that are often dissimilar. By combining the two techniques into one instrument, typical problems encountered with variations in sample preparation and thermal and atmospheric environment are eliminated. This is quite important in the study of polymers since one must match not only temperatures between the two techniques, but also heating rates as well. Matched thermal conditions are necessary because polymer properties such as crystallinity and crystallite size depend on both the temperature and thermal history of the sample under study.

scholarly journals PEEK filament characteristics before and after extrusion within fused filament fabrication process

2022 ◽  
Author(s):  
Cleiton André Comelli ◽  
Richard Davies ◽  
HenkJan van der Pol ◽  
Oana Ghita
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Extrusion Process ◽  
X Ray Diffraction ◽  
Fused Filament Fabrication ◽  
Scanning Calorimetry ◽  
Fast Scanning Calorimetry ◽  
Transmission Electron ◽  
Before And After ◽  
History Of

AbstractThe heating and extrusion process in fused filament fabrication (FFF) is significantly shorter than the conventional extrusion process where longer heating times and significant pressure are applied. For this reason, it is important to understand whether the crystal history of the feedstock is fully erased through the FFF process and whether the FFF process can be tailored further by engineering the crystallization of the feedstock filaments. In this context, a methodology for evaluating the influence of morphology and mechanical properties on different feedstock and extruded filaments is proposed. Filaments with three different PEEK 450G crystalline structures (standard crystallinity, drawn filament and amorphous filament) were selected and evaluated, before and after free extrusion. The resulting morphology, crystallinity and mechanical properties of the extruded filaments were compared against the feedstock properties. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential and fast scanning calorimetry (DSC/FDSC) and tensile test were the techniques used to evaluate the materials. The results showed clear differences in the properties of the feedstock materials, while the analysis of the extruded filaments points to a homogenization of the resulting material producing mostly similar mechanical properties. However, the use of the drawn filament highlighted a statistically significant improvement in crystallinity and mechanical performance, especially in strain values. This conclusion suggests the innovative possibility of improving the quality of manufactured parts by tailoring the microstructure of the feedstock material used in the FFF process. Graphical abstract

Effect of different amounts of modified talc on the mechanical, thermal, and crystallization properties of poly(butylene succinate)

2014 ◽  
Vol 34 (4) ◽  
pp. 379-385 ◽  
Author(s):  
Bingxin Sun ◽  
Chengzhi Chuai ◽  
Si Luo ◽  
Ying Guo ◽  
Chunyang Han
Keyword(s):  
Thermal Stability ◽  
Mechanical Test ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Electron Microscopic ◽  
Butylene Succinate ◽  
Crystallinity Degree ◽  
Crystallization Properties ◽  
Twin Screw ◽  
Microscopic Studies

Abstract Poly(butylene succinate) (PBS) with different ratios of modified talc was prepared by twin-screw extruding. The effect of different loading amounts of talc on the mechanical, thermal, and crystallization properties of PBS was investigated. The mechanical test results indicate that the stiffness of the composites was increased linearly with increasing talc content, and the tensile strength and elongation stayed at relatively high levels when the talc amount is <15 phr. Thermal gravimetric analysis showed that the thermal stability of PBS composites was improved notably with a small amount (5–10 phr) of talc; however, high loading of talc did not help further improve the thermal stability. Differential scanning calorimetry data showed that the melting enthalpy (ΔHm), crystallization enthalpy (ΔHc), and crystallinity degree (Xc) decreased when the talc increased and crystallization temperature (Tc) was moving to relatively high values. The results of X-ray diffraction demonstrated that the incorporation of talc inhibited the PBS crystallization behavior significantly but did not change the crystal structure. Scanning electron microscopic studies indicated that the homogeneous dispersion and smoother fracture surfaces of the composite became inhomogeneous and coarse with higher talc loading.

scholarly journals Shadow glass transition as a thermodynamic signature of β relaxation in hyper-quenched metallic glasses

2020 ◽  
Vol 7 (12) ◽  
pp. 1896-1905 ◽  
Author(s):  
Qun Yang ◽  
Si-Xu Peng ◽  
Zheng Wang ◽  
Hai-Bin Yu
Keyword(s):  
Glass Transition ◽  
Metallic Glasses ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Present Evidence ◽  
Fast Scanning Calorimetry ◽  
Β Relaxation ◽  
Temperature Time ◽  
Anomalous Heat ◽  
Glass Properties

Abstract One puzzling phenomenon in glass physics is the so-called ‘shadow glass transition’ which is an anomalous heat-absorbing process below the real glass transition and influences glass properties. However, it has yet to be entirely characterized, let alone fundamentally understood. Conventional calorimetry detects it in limited heating rates. Here, with the chip-based fast scanning calorimetry, we study the dynamics of the shadow glass transition over four orders of magnitude in heating rates for 24 different hyper-quenched metallic glasses. We present evidence that the shadow glass transition correlates with the secondary (β) relaxation: (i) The shadow glass transition and the β relaxation follow the same temperature–time dependence, and both merge with the primary relaxation at high temperature. (ii) The shadow glass transition is more obvious in glasses with pronounced β relaxation, and vice versa; their magnitudes are proportional to each other. Our findings suggest that the shadow glass transition signals the thermodynamics of β relaxation in hyper-quenched metallic glasses.

scholarly journals Study of poly(L-lactide) using Fast Scanning Calorimetry

2020 ◽  
Vol 6 (3) ◽  
pp. 422-425
Author(s):  
Daniela Arbeiter ◽  
Stefan Oschatz ◽  
Sabine Illner ◽  
Niels Grabow
Keyword(s):  
Thermal Properties ◽  
Quantitative Analysis ◽  
Small Sample ◽  
Analytical Tool ◽  
Solution Casting ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Fast Scanning Calorimetry ◽  
Small Sample Sizes

AbstractFast scanning calorimetry (FSC) is an effective analytical tool to characterize the thermal properties of polymers. Heating rates up to 100 000 K/s allow studies at time scales inaccessible with conventional calorimeters, whose rates are typically less than about 0.5 K/s. Recent studies have successfully demonstrated methods for obtaining quantitative analysis of thermal properties of polymer samples using chip-based FSC. Therefore very small sample sizes, such as particles or nonwovens, can be characterized. In this study, we investigated the thermal properties of poly(L-lactide) PLLA with FSC compared to the results from standard DSC methods. PLLA specimens were fabricated via solution casting and needle electrospinning. The results suggest a significant influence of heating rates on the melting temperature of PLLA. The results show that different fabrication methods lead to changes in crystallinity and that FSC results are not completely comparable with standard DSC measurements.

scholarly journals Bio-Based Poly(butylene succinate)/Microcrystalline Cellulose/Nanofibrillated Cellulose-Based Sustainable Polymer Composites: Thermo-Mechanical and Biodegradation Studies

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1472 ◽  
Author(s):  
Oskars Platnieks ◽  
Sergejs Gaidukovs ◽  
Anda Barkane ◽  
Aleksandrs Sereda ◽  
Gerda Gaidukova ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Microcrystalline Cellulose ◽  
Nanofibrillated Cellulose ◽  
Mechanical Analysis ◽  
Sem Analysis ◽  
Scanning Calorimetry ◽  
Butylene Succinate ◽  
Crystallinity Degree ◽  
Sustainable Housing ◽  
Degradation Temperature

Biodegradable polymer composites from renewable resources are the next-generation of wood-like materials and are crucial for the development of various industries to meet sustainability goals. Functional applications like packaging, medicine, automotive, construction and sustainable housing are just some that would greatly benefit. Some of the existing industries, like wood plastic composites, already encompass given examples but are dominated by fossil-based polymers that are unsustainable. Thus, there is a background to bring a new perspective approach for the combination of microcrystalline cellulose (MCC) and nanofibrillated cellulose (NFC) fillers in bio-based poly (butylene succinate) matrix (PBS). MCC, NFC and MCC/NFC filler total loading at 40 wt % was used to obtain more insights for wood-like composite applications. The ability to tailor the biodegradable characteristics and the mechanical properties of PBS composites is indispensable for extended applications. Five compositions have been prepared with MCC and NFC fillers using melt blending approach. Young’s modulus in tensile test mode and storage modulus at 20 °C in thermo-mechanical analysis have increased about two-fold. Thermal degradation temperature was increased by approximately 60 °C compared to MCC and NFC. Additionally, to estimate the compatibility of the components and morphology of the composite’s SEM analysis was performed for fractured surfaces. The contact angle measurements testified the developed matrix interphase. Differential scanning calorimetry evidenced the trans-crystallization of the polymer after filler incorporation; the crystallization temperature shifted to the higher temperature region. The MCC has a stronger effect on the crystallinity degree than NFC filler. PBS disintegrated under composting conditions in a period of 75 days. The NFC/MCC addition facilitated the specimens’ decomposition rate up to 60 days

Perspectives of Reforming the System of Interbudget Relations in Russia (in the Light of the International Experience)

2006 ◽  
pp. 112-127 ◽  
Author(s):  
V. Nazarov
Keyword(s):  
Social Welfare ◽  
Intergovernmental Relations ◽  
International Experience ◽  
Point Of View ◽  
Short History ◽  
History Of

The attempts to reconstruct the instruments of interbudget relations take place in all federations. In Russia such attempts are especially popular due to the short history of intergovernmental relations. Thus the review of the ¬international experience of managing interbudget relations to provide economic and social welfare can be useful for present-day Russia. The author develops models of intergovernmental relations from the point of view of making decisions about budget authorities’ distribution. The models that can be better applied in the Russian case are demonstrated.

Beérkezett könyvek

2008 ◽  
Vol 63 (4) ◽  
pp. 769-770
Author(s):  
Csaba Pléh
Keyword(s):  
New York ◽  
Point Of View ◽  
Cambridge University ◽  
New Science ◽  
Oxford University ◽  
History Of ◽  
The Mind ◽  
Oxford University Press

Danziger, Kurt: Marking the mind. A history of memory . Cambridge University Press, Cambridge, 2008Farkas, Katalin: The subject’s point of view. Oxford University Press, Oxford, 2008MosoninéFriedJudités TolnaiMárton(szerk.): Tudomány és politika. Typotex, Budapest, 2008Iacobini, Marco: Mirroring people. The new science of how we connect with others. Farrar, Straus and Giroux, New York, 2008Changeux, Jean-Pierre. Du vrai, du beau, du bien.Une nouvelle approche neuronale. Odile Jacob, PárizsGazzaniga_n

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