scholarly journals Crystallinity of Electrospun and Centrifugal Spun Polycaprolactone Fibers: A Comparative Study

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Eva Kuzelova Kostakova ◽  
Laszlo Meszaros ◽  
Gabriela Maskova ◽  
Lenka Blazkova ◽  
Tamas Turcsan ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Production Technology ◽  
Average Molecular Weight ◽  
Degree Of Crystallinity ◽  
Fibrous Materials ◽  
Scanning Calorimetry ◽  
Crystallinity Degree ◽  
A Minor ◽  
Technology Effects ◽  
The Degree Of Crystallinity

Crystalline properties of semicrystalline polymers are very important parameters that can influence the application area. The internal structure, like the mentioned crystalline properties, of polymers can be influenced by the production technology itself and by changing technology parameters. The present work is devoted to testing of electrospun and centrifugal spun fibrous and nanofibrous materials and compare them to foils and granules made from the same raw polymer. The test setup reveals the structural differences caused by the production technology. Effects of average molecular weight are also exhibited. The applied biodegradable and biocompatible polymer is polycaprolactone (PCL) as it is a widespread material for medical purposes. The crystallinity of PCL has significant effect on rate of degradation that is an important parameter for a biodegradable material and determines the applicability. The results of differential scanning calorimetry (DSC) showed that, at the degree of crystallinity, there is a minor difference between the electrospun and centrifugal spun fibrous materials. However, the significant influence of polymer molecular weight was exhibited. The morphology of the fibrous materials, represented by fiber diameter, also did not demonstrate any connection to final measured crystallinity degree of the tested materials.

scholarly journals Impact of environmental agents on non-woven polylactide/natural rubber agrofiber

2021 ◽  
Vol 285 ◽  
pp. 07034
Author(s):  
Yulia Tertyshnaya ◽  
Maksim Zakharov ◽  
Alina Ivanitskikh ◽  
Anatoliy Popov
Keyword(s):  
Natural Rubber ◽  
Uv Irradiation ◽  
Thermal Characteristics ◽  
Degree Of Crystallinity ◽  
Distilled Water ◽  
Fibrous Materials ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Environmental Agents ◽  
The Degree Of Crystallinity

In the work an eco-friendly non-woven fiber made of polylactide and natural rubber with a rubber content from 0 to 15 wt.% was obtained by electrospinning. The influence of distilled water and UV irradiation on the agrofibers has been investigated. The water sorption test showed that the addition of natural rubber into the polylactide matrix does not significantly affect the degree of water absorption of the fibrous materials, which is in the range of 49-50.6%. Thermal characteristics after 180 days of degradation in distilled water at 22±2 oC and UV irradiation at a wavelength of 365 nm during 100 hours were determined using the differential scanning calorimetry. Changes in the values for glass transition and melting temperatures, and the degree of crystallinity were determined.

Investigation of the Crystallization of Polyetherketones by the Differential Scanning Calorimetry Method

2018 ◽  
Vol 935 ◽  
pp. 36-39 ◽  
Author(s):  
Azamat A. Zhansitov ◽  
Azamat L. Slonov ◽  
Arthur E. Baikaziev ◽  
Marina M. Murzakanova ◽  
S.Yu. Khashirova
Keyword(s):  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Phase Transitions ◽  
Crystallization Temperature ◽  
Amorphous Structure ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polyether Ether Ketone ◽  
Ether Ketone ◽  
The Degree Of Crystallinity

Differential scanning calorimetry was used to study the temperatures and character of phase transitions of fibers based on polyether ether ketones. It is shown that in the production of fine fibers from polyether ether ketones, a predominantly amorphous structure is formed. Increasing the temperature to the crystallization temperature leads to an almost twofold increase in the degree of crystallinity. Lower molecular weight polyether ether ketone is characterized by a higher rate of crystallization and the formation of a more homogeneous crystalline structure.

scholarly journals Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Emi Govorčin Bajsić ◽  
Vesna Rek ◽  
Ivana Ćosić
Keyword(s):  
Thermal Properties ◽  
Thermoplastic Polyurethane ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polypropylene Blends ◽  
Pp Blends ◽  
The Degree Of Crystallinity ◽  
Better Than

The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends.

Characterization of bi-layered magnetic nanoparticles synthesized via two-step surface-initiated ring-opening polymerization

2015 ◽  
Vol 87 (11-12) ◽  
pp. 1085-1097 ◽  
Author(s):  
Li Wang ◽  
Stefan Baudis ◽  
Karl Kratz ◽  
Andreas Lendlein
Keyword(s):  
Magnetic Nanoparticles ◽  
Ring Opening ◽  
Average Molecular Weight ◽  
Polymer Networks ◽  
Gel Permeation Chromatography ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Transmission Electron

AbstractA versatile strategy to integrate multiple functions in a polymer based material is the formation of polymer networks with defined nanostructures. Here, we present synthesis and comprehensive characterization of covalently surface functionalized magnetic nanoparticles (MNPs) comprising a bi-layer oligomeric shell, using Sn(Oct)2 as catalyst for a two-step functionalization. These hydroxy-terminated precursors for degradable magneto- and thermo-sensitive polymer networks were prepared via two subsequent surface-initiated ring-opening polymerizations (ROPs) with ω-pentadecalactone and ε-caprolactone. A two-step mass loss obtained in thermogravimetric analysis and two distinct melting transitions around 50 and 85°C observed in differential scanning calorimetry experiments, which are attributed to the melting of OPDL and OCL crystallites, confirmed a successful preparation of the modified MNPs. The oligomeric coating of the nanoparticles could be visualized by transmission electron microscopy. The investigation of degrafted oligomeric coatings by gel permeation chromatography and 1H-NMR spectroscopy showed an increase in number average molecular weight as well as the presence of signals related to both of oligo(ω-pentadecalactone) (OPDL) and oligo(ε-caprolactone) (OCL) after the second ROP. A more detailed analysis of the NMR results revealed that only a few ω-pentadecalactone repeating units are present in the degrafted oligomeric bi-layers, whereby a considerable degree of transesterification could be observed when OPDL was polymerized in the 2nd ROP step. These findings are supported by a low degree of crystallinity for OPDL in the degrafted oligomeric bi-layers obtained in wide angle X-ray scattering experiments. Based on these findings it can be concluded that Sn(Oct)2 was suitable as catalyst for the preparation of nanosized bi-layered coated MNP precursors by a two-step ROP.

Effects of the Different Crystallization Time on Synthesis of Zeolite 4A from by-Products of Polysilicon Production Process

2011 ◽  
Vol 347-353 ◽  
pp. 246-251
Author(s):  
Xing Yong Liu ◽  
Min Li ◽  
Hong Chen ◽  
Wei Wei
Keyword(s):  
Production Process ◽  
Degree Of Crystallinity ◽  
Crystallization Time ◽  
Crystallinity Degree ◽  
Structure Morphology ◽  
Zeolite 4A ◽  
Single Structure ◽  
Ft Ir ◽  
The Degree Of Crystallinity ◽  
By Products

Pure form,single phase and high crystalline zeolite 4A samples were synthesized during hydrothermal treatment of by-products in polysilicon production process. The effects of the different crystallization time on the degree of crystallinity, skeleton structure, morphology, size of the particle and its distribution of zeolite 4A samples were investigated using XRD,FT-IR,SEM and Zetasizer. The results indicated that the zeolite 4A sample featured high crystallinity degree, excellent dispersivity, high purity and single structure.

scholarly journals Effect of Heterogeneous Deacetylation on the Properties of Northern Shrimp Chitin and Chitosan

2020 ◽  
Author(s):  
Nataliia Dolgopiatova ◽  
Yuliya Kuchina ◽  
Tatiana Dyakina ◽  
Tatiana Volkova
Keyword(s):  
Molecular Weight ◽  
Shear Stress ◽  
Alkaline Treatment ◽  
Degree Of Crystallinity ◽  
Repeated Treatment ◽  
Experimental Conditions ◽  
Northern Shrimp ◽  
Chitin And Chitosan ◽  
Chitosan Deacetylation ◽  
The Degree Of Crystallinity

The effect of alkaline treatment of shrimp chitin on the molecular weight, the degree of deacetylation and degree of crystallinity of the resulting chitosan is studied. The viscosity of chitosan solutions from repeatedly deacetylated chitin is studied. It is shown that repeated treatment of chitin/chitosan with alkali causes the destruction of polysaccharide macromolecules. After four-time deacetylation and one-time deacetylation of chitin/chitosan for four hours, the molecular weight of the polysaccharide decreases by ten times. The maximum degree of chitosan deacetylation under experimental conditions was 92.0 -92.5%. The diffractograms of chitin and chitosan from the Northern shrimp are of the form typical for samples containing an amorphous phase in addition to a crystalline phase. The degree of crystallinity of chitin from Northern shrimp was 40.8%, of chitosan samples after one-, two-, and three-time deacetylation was 62-65%. For a sample of chitosan obtained after four-time deacetylation, recrystallization, and drying in a freeze dryer, the degree of crystallinity is close to the degree of crystallinity of shrimp chitin. The investigated acetic acid chitosan solutions with a concentration of 5% (wt.) and the chitosan molecular weight of 250, 160 and 130 kDa in their rheological properties are liquid-like non-Newtonian systems, their viscosity decreasing with increasing shear stress. After four-time deacetylation of chitin, the viscosity of chitosan solutions practically does not change with increasing shear stress, which apparently can be due to a significant decrease in the molecular weight of chitosan under these conditions.

scholarly journals The Effect of Crystallinity on the Toughness of Cast Polyamide 6 Rods with Different Diameters

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 293
Author(s):  
Miklós Odrobina ◽  
Tamás Deák ◽  
László Székely ◽  
Tamás Mankovits ◽  
Róbert Zsolt Keresztes ◽  
...  
Keyword(s):  
Impact Strength ◽  
Impact Test ◽  
Charpy Impact ◽  
Polyamide 6 ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Tensile Impact ◽  
Different Diameters ◽  
The Impact ◽  
The Degree Of Crystallinity

The present paper concentrates on the toughness and the degree of crystallinity of the magnesium-catalyzed polyamide 6 rods cast in different diametres, which are commonly used for gear manufacturing. Its toughness cannot be regarded as a constant feature due to the casting technology. The mechanical properties of the semi-finished products are sensitive to the manufactured dimension, e.g., cast diameter, which are investigated by the Charpy impact test and tensile impact test. It is generally accepted that the impact strength and tensile-impact strength correlate with the degree of crystallinity beside many other material’s feature. Crystallinity is evaluated by Differential Scanning Calorimetry. The aim of this study is to determine the relationship between toughness and crystallinity of the magnesium-catalyzed cast PA6 rods with different diameters. For the research cast rods between 40 and 300 mm diameter were selected in seven-dimensional steps. Based on the results, it was found that the toughness depends strongly on the diameter size. Furthermore, it is proved that the crystallinity explains 62.3% of the variation of the Charpy’s impact strengths, while the tensile impact method was not suitable to detect the difference between the test samples.

scholarly journals Hemp Fibre Reinforced Poly(Lactic Acid) Composites

2007 ◽  
Vol 29-30 ◽  
pp. 337-340 ◽  
Author(s):  
M.A. Sawpan ◽  
K.L. Pickering ◽  
Alan Fernyhough
Keyword(s):  
Lactic Acid ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Hemp Fibre ◽  
Reinforcing Material ◽  
Fibre Loading ◽  
The Degree Of Crystallinity

The potential of hemp fibre as a reinforcing material for Poly(lactic acid) (PLA) was investigated. Good interaction between hemp fibre and PLA resulted in increases of 100% for Young’s modulus and 30% for tensile strength of composites containing 30 wt% fibre. Different predictive ‘rule of mixtures’ models (e.g. Parallel, Series and Hirsch) were assessed regarding the dependence of tensile properties on fibre loading. Limited agreement with models was observed. Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) studies showed that hemp fibre increased the degree of crystallinity in PLA composites.

Synthesis of Segmented Anisotropic-Isotropic Poly(Aryl Ester)Poly(Arylene Ether) Copolymers

1989 ◽  
Vol 175 ◽  
Author(s):  
J. E. McGratn ◽  
K. L. Cooper ◽  
W. Waehamad ◽  
H. Huang ◽  
G. L. Wilkes
Keyword(s):  
Molecular Weight ◽  
Liquid Crystal ◽  
Benzoic Acid ◽  
Liquid Crystalline ◽  
Average Molecular Weight ◽  
Nucleophilic Aromatic Substitution ◽  
Copolymer Composition ◽  
Aromatic Substitution ◽  
Scanning Calorimetry ◽  
Arylene Ether

AbstractCarboxyl functional poly(arylene ether) oligomers of controlled number average molecular weight were synthesized via nucleophilic aromatic substitution step polymerization using p-hydroxy benzoic acid as the molecular weight and end group controlling reagents. The subsequent functionalized polyarylene ethers were copolymerized with acetoxy benzoic acid or acetoxyphenoxy benzoic acid via melt acidolysis procedures. Successful copolymers were generated using chlorobenzene as a solvent for the first s age of the reaction followed by melt reaction at temperatures as high as 325°C. Resulting copolymer composition and segment size were investigated. It was possible to prepare improved solvent resistant copolymers through incorporation of the liquid crystal polyester (LCP) segment. Extraction tests using boiling chloroform showed that a high percentage of segmented copolymer were generated. Swelling characteristics were also noted and were observed to decrease as a function of the LCP concentration utilized. Multiple transitions were observed in differential scanning calorimetry consistent with Tg's, Tm's and possibly with liquid crystal transitions. Optical microscopy showed an ordered microstructure developed which is consistent with the presence of liquid crystalline phases. The materials were successfully compression molded to afford tough coherent films at all compositions, implying the likelihood of improved compressive strength relative to the LCP homo- or copolyesters.

Investigating the Effect of Nanoclay Loadings and Re-Processing on the Melting and Crystallization Behavior of PP/Clay Nanocomposites

2019 ◽  
Vol 951 ◽  
pp. 21-25
Author(s):  
Achmad Chafidz ◽  
Sholeh Ma'mun ◽  
Haryanto ◽  
Wara Dyah Pita Rengga ◽  
Prima A. Handayani ◽  
...  
Keyword(s):  
Crystallization Behavior ◽  
Crystallization Process ◽  
The Other ◽  
Degree Of Crystallinity ◽  
Clay Nanocomposites ◽  
Scanning Calorimetry ◽  
Onset Crystallization Temperature ◽  
Significant Difference ◽  
The Degree Of Crystallinity ◽  
Melting And Crystallization

In this study, PP/clay nanocomposites have been fabricated at different nanoclay loadings, i.e. 0, 5, 10, and 5 wt% for the 1stcycle and 2ndcycle (re-processing). The prepared nanocomposites were then characterized by a Differential Scanning Calorimetry (DSC) to investigate the effects of nanoclay loadings and re-processing on the melting and crystallization of the nanocomposites. The DSC results showed that the melting temperature,Tmwas not significantly affected by the nanoclay loadings and re-processing. In the other hand, the degree of crystallinity,Xcof the nanocomposites was higher than that of neat PP, but only reached a maximum at nanoclay loading of 5 wt% (i.e. 51.2% for NC-5-I and 48.3% for NC-5-II). Thereafter, theXcdecreased at higher nanoclay loadings. There was no significant difference inXcbetween 1stcycle and 2ndcycle. Additionally, in all nanocomposites samples for both cycles, there were two crystallization temperatures, i.e.Tc1andTc2. In the overall crystallization process, theTcof nanocomposites increased by 11-12°C compared to that of neat PP. Whereas, the onset crystallization temperature,Tocalso increased by approx. 13°C. Apparently, there was no significant effect of nanoclay loadings and re-processing on theTcndTocof the nanocomposites.

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