scholarly journals Tuning the mechanical properties and degradation properties of polydioxanone isothermal annealing

2020 ◽  
Vol 44 (5) ◽  
pp. 1430-1444
Author(s):  
Xiliang LIU ◽  
Shaomin FENG ◽  
Xin WANG ◽  
Jin QI ◽  
Dong LEI ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Isothermal Annealing ◽  
Hydrolytic Degradation ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Optical Micrograph ◽  
Potential Applications ◽  
Degradation Properties ◽  
The Degree Of Crystallinity

Polydioxanone (PPDO) is synthesized by ring-opening polymerization of p-dioxanone, using stannous octoate as the catalyst. The polarized optical micrograph (POM) shows thes pherulite growth rate of PPDO decreases with an increase in the isothermal crystallization temperature. PPDO is compression-molded into bars, and PPDO bars are subjected to isothermal annealing at a range of temperatures (Ta = 50, 60, 70, 80, 90, and 100 °C), and correspond to three different annealing times (ta = 1h, 2h, 3h). The effect on PPDO is investigated by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). With an increase in Ta and ta, the grain size and the degree of crystallinity also increase. Meanwhile, the tensile strength is significantly improved. The PPDO bars (90 °C, 2 h) reach the maximum crystallinity (57.21%) and the maximum tensile strength (41.1 MPa). Interestingly, the heat treatment process does not result in serious thermal degradation. It is observed that the hydrolytic degradation of the annealed PPDO is delayed to some extent. Thus, annealed PPDO might have potential applications, particularly in the fields of orthopedic fixation and tissue engineering.

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.

Study of the structure and thermal characteristics of nanocomposites based on polyvinyl alcohol and intercalated montmorillonite

2019 ◽  
pp. 089270571987919
Author(s):  
Volodymyr Krasinskyi ◽  
Ivan Gajdos ◽  
Oleh Suberlyak ◽  
Viktoria Antoniuk ◽  
Tomasz Jachowicz
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Acrylic Acid ◽  
Polyvinyl Alcohol ◽  
Thermal Characteristics ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Degree Of Crystallinity

The structure and thermal characteristics of nanocomposites based on polyvinyl alcohol (PVA) and montmorillonite (MMT) intercalated with polyvinylpyrrolidone were investigated by X-ray diffraction analysis and differential scanning calorimetry. The modification of PVA with intercalated MMT reduces the degree of crystallinity of the resulting nanocomposites but significantly increases their thermal stability. Under ultrasound, the intercalated MMT was completely distributed in a PVA solution and formed a monocrystalline structure. Films based on PVA with modified MMT were cross-linked at 110°C in the presence of 5 wt% acrylic acid and 0.5 wt% Ferrous(II) sulfate as an initiator. The formed films have a homogeneous cross-linked structure.

scholarly journals Development and Characterization of Novel Polyurethane Films Impregnated with Tolfenamic Acid for Therapeutic Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Hilal Istanbullu ◽  
Sofia Ahmed ◽  
Muhammad Ali Sheraz ◽  
Ihtesham ur Rehman
Keyword(s):  
Polymer Concentration ◽  
Tolfenamic Acid ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Release Studies ◽  
Evaporation Technique ◽  
Crystallinity Changes ◽  
The Degree Of Crystallinity

The present study deals with the preparation of polyurethane (PU) films impregnated with a nonsteroidal anti-inflammatory drug, tolfenamic acid (TA). Solvent evaporation technique has been employed for the preparation of TA-PU films in two different ratios of 1 : 2 and 1 : 5 in Tetrahydrofuran (THF) or THF-ethanol mixtures. The prepared films were characterized using X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and release studies. The results indicate transformation of crystalline TA to its amorphous form. The degree of crystallinity changes both by increasing the polymer concentration and solvent used for the film preparations. The release profiles of TA were also found to be affected, showing a decrease from approximately 50% to 25% from 1 : 2 to 1 : 5 ratios, respectively.

Physicochemical Properties of Porous Starches from Different Botanical Origin

2010 ◽  
Vol 159 ◽  
pp. 363-370
Author(s):  
Hua Xi Xiao ◽  
Qin Lu Lin ◽  
Yue Wu ◽  
Wei Tian ◽  
Wei Wu
Keyword(s):  
Potato Starch ◽  
Enzyme Hydrolysis ◽  
Degree Of Crystallinity ◽  
Rice Starch ◽  
Adsorptive Capacity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Potato Starches ◽  
The Degree Of Crystallinity

Rice, maize and potato starches were hydrolyzed by amylase to obtain porous starches as final product. The adsorptive capacity, desorbed rates, degree of crystallinity and retrogradation properties of native and porous starches were investigated. The results showed that porous starches had the stronger adsorptive capacity and slower desorbed rate compared with native starches. In the three starch materials, the adsorptive capacity of rice starch for liquids was the strongest; the adsorptive capacity of potato starch for liquids was the weakest. the more flavors adsorbed, the more flavors desorbed. X-ray diffraction showed that Enzyme hydrolysis did not result in any significant changes in the degree of crystallinity of starch. The porous starches exhibited lower tendency of retrogradation as assessed by differential scanning calorimetry (DSC).

scholarly journals An insight on the process–property relationships of melt spun polylactic acid fibers

2019 ◽  
Vol 89 (23-24) ◽  
pp. 4959-4966 ◽  
Author(s):  
AM Ali ◽  
HM El-Dessouky
Keyword(s):  
Polylactic Acid ◽  
High Performance ◽  
Polarized Light ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Laser Diffractometry ◽  
Wide Range ◽  
Innovative Materials ◽  
The Degree Of Crystallinity

Polylactic acid (PLA) fibers are receiving growing interest as one of the recent innovative materials being developed for various applications. The inherent biodegradability of PLA makes it highly attractive for the biomedical and health care sectors. PLA fibers need to be partially and/or highly oriented to allow high performance and readiness for a wide range of manufacturability. In this study, the structure and properties of PLA fibers, manufactured at different spinning speeds, were studied. Laser diffractometry, polarized light microscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to determine the diameter, birefringence, molecular orientation, enthalpy and degree of crystallinity of as-spun and drawn PLA fibers. The results of DSC and XRD showed that the degree of crystallinity of the PLA fibers is significantly improved for the drawn PLA fibers compared to the as-spun fibers and leveled off in the case of changing the take-up speeds of drawn fibers.

Blending and plasticising effects on the behaviour of poly(lactic acid)/poly(ε-caprolactone)

2018 ◽  
Vol 26 (5-6) ◽  
pp. 337-345 ◽  
Author(s):  
Nesrine Khitas ◽  
Kamira Aouachria ◽  
Mohamed Tahar Benaniba
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Triethyl Citrate ◽  
Acetyl Tributyl Citrate ◽  
The Degree Of Crystallinity

Polymer blending is one of the most convenient methods to be used to overcome the limitations of some single properties of polymers and to achieve the combinations required for specific applications. Another feasible common practice is the incorporation of additives of low molecular weight such as plasticisers to impart flexibility, improve toughness and lower the glass transition temperature ( Tg). This study focused on the effects of blending and plasticising on the crystallisation behaviour of poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL). PCL with longer degradation time compared with other polymers was blended with PLA to overcome the limitation of its brittleness and poor thermal stability. Acetyl tributyl citrate (ATBC) and acetyl triethyl citrate (TEC) were used as plasticiser in PLA/PCL blends. The rigid and plasticised blends at various ratios were analysed by differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The results revealed a slight increase in the degree of crystallinity and a significant increase in the Tg of PLA due to the addition of PCL. The addition of ATBC has promoted a decrease in thermal stability of the blends. The slight increase in the degree of crystallinity suggested that PCL acted as a nucleating agent. The citrate plasticisers were shown to lower the Tg and have much more enhanced the crystallisation of PLA. Moreover, the rigid and plasticised blends were shown to be partially miscible.

scholarly journals Impact of Water and UV Irradiation on Nonwoven Polylactide/Natural Rubber Fiber

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 461
Author(s):  
Yulia Tertyshnaya ◽  
Maria Podzorova ◽  
Maksim Moskovskiy
Keyword(s):  
Natural Rubber ◽  
Uv Irradiation ◽  
Hydrolytic Degradation ◽  
Thermal Characteristics ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Melt Flow Rate ◽  
Phase Transition Temperatures ◽  
Nonwoven Fiber ◽  
The Degree Of Crystallinity

A nonwoven fiber made of polylactide/natural rubber with a rubber content from 0 to 15 wt.% was obtained by electrospinning from a solution. The water sorption test showed that the addition of natural rubber into the polylactide matrix did not significantly affect the degree of water absorption of the fibers, which was in the range of 48.9–50.6%. The melt flow rate only increased by 0.5 g/10 min at a content of 15 wt.% natural rubber. The thermal characteristics after 120 days of degradation in distilled water and UV irradiation (50 h) at a wavelength of 365 nm were determined using differential scanning calorimetry. Changes in the values of the phase transition temperatures and the degree of crystallinity were determined. It was determined that the fiber samples from all compositions retained the propensity for photo- and hydrolytic degradation.

Preparation and Characterization of Polyacrylonitrile in Aqueous Slurry Polymerization

2014 ◽  
Vol 789 ◽  
pp. 215-217
Author(s):  
Ben Lin Lou ◽  
Yuan Yuan Li ◽  
Ru Xiao
Keyword(s):  
Nitrogen Atmosphere ◽  
Cyclization Reaction ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Chemical Structures ◽  
Polyacrylonitrile Copolymer ◽  
Ternary Copolymer ◽  
The Degree Of Crystallinity ◽  
Aqueous Slurry

Polyacrylonitrile (PAN) is widely used for its superior properties, and comonomers are usually introduced to improve its properties. In this paper, 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and acrylamide (AM) were used as comonomers to prepare polyacrylonitrile by aqueous slurry polymerization. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) was used to characterize the chemical structures, the thermal properties, degree of crystallinity of polyacrylonitrile copolymer. The results show that the best thermal property of AN/AMPS/AM ternary copolymer in cyclization reaction was achieved in the proportion (w/w/w) 98/1/1. The exothermic quantity of AN/AMPS/AM ternary copolymer is 612.1 J/g while that of PAN homopolymer is 519.5 J/g during the cyclization reaction, carried out in DSC under nitrogen atmosphere. The introduction of AMPS and AM has small impact on the degree of crystallinity of PAN, the degree of crystallinity approximates 53.8%

Preparation and Characterization on Cellulose Nanofiber Film

2010 ◽  
Vol 654-656 ◽  
pp. 1760-1763 ◽  
Author(s):  
Li Yuan Zhang ◽  
Takuya Tsuzuki ◽  
Xun Gai Wang
Keyword(s):  
Cellulose Nanofibers ◽  
Average Diameter ◽  
Cellulose Nanofiber ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Image ◽  
Potential Applications ◽  
Reflectance Analysis ◽  
Nanofiber Film

In this study, cellulose nanofibers were obtained from wood pulp using a chemo-mechanical method and thin films were made of these cellulose nanofibers. The morphology of the films was studied by scanning electron microscopy (SEM). SEM image analysis revealed that the films were composed of cellulose nanofibers with an average diameter of around 32 nm. Other properties were also characterized, including the degree of crystallinity by X-ray diffraction, chemical bonding by infrared attenuated total reflectance analysis, and thermal properties by differential scanning calorimetry. The foldable, strong, and optically translucent cellulose nanofiber films thus obtained have many potential applications as micro/nano electronic devices, biosensors and filtration media, etc.

The influence of drawing pressure on the properties of PET/PA6 bicomponent spunbonded fibers

2016 ◽  
Vol 46 (5) ◽  
pp. 1281-1293 ◽  
Author(s):  
Min Wang ◽  
Bin Yu ◽  
Jian Han ◽  
Weimin Song ◽  
Feichao Zhu
Keyword(s):  
Breaking Strength ◽  
Fiber Strength ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Bicomponent Fibers ◽  
Fiber Fineness ◽  
The Degree Of Crystallinity ◽  
Bicomponent Fiber

The properties of fibers were significantly affected by drawing during the spunbond process. In this paper, the influence of drawing pressure on the properties of spunbonded PET/PA6 hollow pie wedge bicomponent filaments was studied, and their performance was characterized by differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, Beion F6 fiber fineness tester, and single fiber strength tester. The hollow pie wedge bicomponent fiber had a distinct interface between the two polymers due to poor compatibility. With increasing of drawing pressure, diameter of the fibers reduced regularly. When the drawing pressure increased, both the degree of crystallinity and orientation of bicomponent fibers enhanced, and the melting point of polyester component increased as well. Furthermore, with increasing of drawing pressure, the breaking strength of the fibers increased, but the breaking elongation and linear density decreased.

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