scholarly journals The Formation of a Highly Oriented Structure and Improvement of Properties in PP/PA6 Polymer Blends during Extrusion-Stretching

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 878
Author(s):  
Yu Wang ◽  
Wenjie Sun ◽  
Song Liu ◽  
Huajian Ji ◽  
Xin Chen ◽  
...  
Keyword(s):  
Polymer Blends ◽  
Average Diameter ◽  
Barrier Properties ◽  
Polyamide 6 ◽  
Scanning Calorimetry ◽  
Orientation Degree ◽  
Average Size ◽  
Die Extrusion ◽  
Stretching Process ◽  
Slit Die

During the “slit die extrusion-hot stretching” process, highly oriented polyamide 6 (PA6) dispersed phase was produced and retained in the polypropylene (PP) matrix directly. By adjusting the stretching forces, the PA6 spherical phase evolved into the ellipsoid, rod-like microfibril with a decreasing average diameter; then, the PA6 microfibrils broke. Moreover, the effects of the PA6 phases formed in the process of the microfibrillation on PP’s crystallization behaviors were studied systematically. As the stretching forces increased, the crystallization ability and orientation degree of PP crystals improved significantly. Differential scanning calorimetry and polarizing optical microscopy confirmed the formation of PP spherulite, fan-shaped lamellae and a transcrystalline layer under the induction of the PA6 phases with different morphology. In the PP/PA6 microfibrilar composites (MFCs), PP crystals showed smaller average size, more crystals and stronger interface adhesion due to more excellent heterogeneous nucleation ability of the PA6 microfibrils, which made contributions to the improvement of the melt elasticity responses and oxygen barrier properties of the PP/PA6 polymer blends.

scholarly journals Study on Structure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1426
Author(s):  
Tomáš Remiš ◽  
Petr Bělský ◽  
Tomáš Kovářík ◽  
Jaroslav Kadlec ◽  
Mina Ghafouri Azar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Single Step ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Primary Particles ◽  
Solution Casting Method ◽  
Average Size

In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

Probing Three Distinct Crystal Polymorphs of Melt-Crystallized Polyamide 6 by an Integrated Fast Scanning Calorimetry Chip System

2021 ◽  
Author(s):  
Xiaoshi Zhang ◽  
Anne Gohn ◽  
Gamini Mendis ◽  
John F. Buzinkai ◽  
Steven J. Weigand ◽  
...  
Keyword(s):  
Polyamide 6 ◽  
Scanning Calorimetry ◽  
Fast Scanning Calorimetry

Comparative study of thermoplastic liner materials with regard to mechanical and permeation barrier properties before and after cyclic thermal aging

2021 ◽  
Vol 63 (4) ◽  
pp. 311-316
Author(s):  
Simon Backens ◽  
Jan Siering ◽  
Stefan Schmidt ◽  
Nikolai Glück ◽  
Wilko Flügge
Keyword(s):  
Thermal Aging ◽  
Barrier Properties ◽  
Tensile Tests ◽  
Polyamide 6 ◽  
Pressure Vessels ◽  
Cross Linking ◽  
Polyamide 12 ◽  
Type Iv ◽  
Before And After ◽  
Permeation Properties

Abstract Lightweight pressure vessels of type IV for hydrogen storage consist of a thermoplastic inner liner, commonly from polyethylene or polyamide. The liner is the permeation barrier against the compressed gas and must prevent the formation of cracks, also after temperature changes, for example after refueling processes. In the present work high-density polyethylene, cross-linked polyethylene, polyamide 6 and polyamide 12 were characterized by tensile tests, single notch impact tests and permeations measurements before and after a cyclic thermal aging process. The aging only lead to slight changes of mechanical properties due to post-crystallization, but to a significant decrease of permeation properties. This decrease was contributed to weakened, amorphous regions where chain splitting occurred. Considerable differences in properties resulted from different peroxide cross-linking times of polyethylene at the same temperature. A longer holding time at 200 °C led to an improvement in impact strength by a factor of more than three. However, the permeation properties decreased by about 50 %, indicating that peroxide cross-linking in the melt inhibited the formation of crystalline regions.

The non-isothermal crystallization behavior of polyamide 6 and polyamide 6/HDPE/MAH/L-101 composites

2019 ◽  
Vol 39 (2) ◽  
pp. 124-133 ◽  
Author(s):  
Bingxiao Liu ◽  
Guosheng Hu ◽  
Jingting Zhang ◽  
Zhongqiang Wang
Keyword(s):  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Isothermal Condition ◽  
Crystallization Rate ◽  
Polyamide 6 ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Analysis And Design ◽  
Processing Techniques

AbstractStudy of the crystallization kinetics is particularly necessary for the analysis and design of processing operations, especially the non-isothermal crystallization behavior, which is due to the fact that most practical processing techniques are carried out under non-isothermal conditions. The non-isothermal crystallization behaviors of polyamide 6 (PA6) and PA6/high-density polyethylene/maleic anhydride/2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (PA6/HDPE/MAH/L-101) composites were investigated by differential scanning calorimetry (DSC). The crystallization kinetics under non-isothermal condition was analyzed by the Jeziorny and Mo equations, and the activation energy was determined by the Kissinger and Takhor methods. The crystal structure and morphology were analyzed by wide-angle X-ray diffraction (WXRD) and polarized optical microscopy (POM). The results indicate that PA6/HDPE/MAH/L-101 has higher crystallization temperature and crystallization rate, which is explained as due to its heterogeneous nuclei.

scholarly journals Micropipette-Based Microfluidic Device for Monodisperse Microbubbles Generation

Micromachines ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 387
Author(s):  
Carlos Toshiyuki Matsumi ◽  
Wilson José da Silva ◽  
Fábio Kurt Schneider ◽  
Joaquim Miguel Maia ◽  
Rigoberto E. M. Morales ◽  
...  
Keyword(s):  
Electric Fields ◽  
Microfluidic Device ◽  
Soft Lithography ◽  
Low Cost ◽  
Characteristic Curve ◽  
Microfluidic Devices ◽  
Average Diameter ◽  
Internal Diameter ◽  
Medical Diagnostic ◽  
Average Size

Microbubbles have various applications including their use as carrier agents for localized delivery of genes and drugs and in medical diagnostic imagery. Various techniques are used for the production of monodisperse microbubbles including the Gyratory, the coaxial electro-hydrodynamic atomization (CEHDA), the sonication methods, and the use of microfluidic devices. Some of these techniques require safety procedures during the application of intense electric fields (e.g., CEHDA) or soft lithography equipment for the production of microfluidic devices. This study presents a hybrid manufacturing process using micropipettes and 3D printing for the construction of a T-Junction microfluidic device resulting in simple and low cost generation of monodisperse microbubbles. In this work, microbubbles with an average size of 16.6 to 57.7 μm and a polydispersity index (PDI) between 0.47% and 1.06% were generated. When the device is used at higher bubble production rate, the average diameter was 42.8 μm with increased PDI of 3.13%. In addition, a second-order polynomial characteristic curve useful to estimate micropipette internal diameter necessary to generate a desired microbubble size is presented and a linear relationship between the ratio of gaseous and liquid phases flows and the ratio of microbubble and micropipette diameters (i.e., Qg/Ql and Db/Dp) was found.

Preparation of a monodisperse poly (N-phenylmaleimide–acrylonitrile–styrene) structural nanolatex for heat-resistant modification of PVC

2018 ◽  
Vol 32 (3) ◽  
pp. 409-423
Author(s):  
Jin Wang ◽  
Hua Qiu ◽  
Bo Cheng ◽  
Fan Zhang ◽  
Shuhua Qi
Keyword(s):  
Electron Microscope ◽  
Elemental Analysis ◽  
Hybrid Composite ◽  
Average Diameter ◽  
Microemulsion Polymerization ◽  
Scanning Calorimetry ◽  
Thermogravimetric Analyzer ◽  
Melt Compounding ◽  
Transmission Electron ◽  
Ftir Spectrometer

A monodisperse poly ( N-phenylmaleimide–acrylonitrile–styrene) (PNAS) nanolatex was synthesized via seed microemulsion polymerization. The obtained PNAS nanolatex was then directly used as an organic nanofiller to prepare polyvinyl chloride (PVC)/PNAS hybrid composite through water blending and melt compounding. The characteristics of PNAS nanolatex were analyzed by Fourier transform infrared (FTIR) spectrometer, elemental analysis, scanning electron microscope, transmission electron microscope (TEM), dynamic laser lighting scattering (DLS), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). FTIR and elemental analysis confirmed the formation of PNAS copolymer with high monomers conversion; meanwhile, for the PNAS nanoparticles, the morphology of a well-defined core–shell spherical structure with average diameter ranging from 156 nm to 249 nm was observed. DSC analysis and TGA indicated that both polymers had excellent compatibility, and the corresponding heat resistance of PVC was greatly improved with the addition of PNAS. When PNAS loading was 50 wt%, the glass transition temperature value of PVC/PNAS hybrid composite was increased by 22.4°C, compared with that of pristine PVC. The mechanical properties of the PVC composite were also enhanced with the addition of PNAS.

Thermal and Tensile Properties of PP Nanocomposite Blends

2008 ◽  
Vol 47-50 ◽  
pp. 21-24
Author(s):  
C. Rosales ◽  
V. Contreras ◽  
M. Matos ◽  
R. Perera ◽  
N. Villarreal ◽  
...  
Keyword(s):  
Tensile Modulus ◽  
Polyamide 6 ◽  
Dispersed Phase ◽  
Scanning Calorimetry ◽  
Binary Blend ◽  
Polyethylene Blends ◽  
Metallocene Polyethylene ◽  
The Matrix ◽  
Twin Screw ◽  
Layered Clay

Polypropylene/polyamide-6 and polypropylene/metallocene polyethylene blends containing 2.5 phr of organophilic modified montmorillonite were prepared in a twin-screw extruder followed by injection molding. In order to compare, blends without layered clay were also made. Styreneethylene- butylene-styrene copolymer and polypropylene grafted with anhydride maleic were used as compatibilizers in the ternary blends and in the PP nanocomposite preparation, respectively. The presence of tactoids, intercalated and exfoliated structures was observed by TEM in some of the samples containing layered clay and modified PP materials. Results showed that the compatibilized blends prepared without clay are tougher than those prepared with the nanocomposite of PP as the matrix phase and no significant changes in tensile moduli were observed between them. However, the binary blend with a nanocomposite of PP as matrix and metallocene polyethylene exhibited better tensile toughness and lower tensile modulus, than those prepared with a nanocomposite of PP and polyamide-6 as dispersed phase. These results are related to the degree of clay dispersion in the PP and to the type of morphology developed in the different blends. Differential scanning calorimetry (DSC) showed that blends with a finer and homogeneously dispersed morphology determined by SEM, the PA component exhibited fractionated crystallization exotherms in the temperature range of 159-185°C. Also, nucleation of the PP component by PA phase and/or the layered clay was observed in the blends with PA as dispersed phase.

Synthesis of LiCoO2 particles with tunable sizes by a urea-based-homogeneous-precipitation method

2020 ◽  
Vol 111 (4) ◽  
pp. 347-355
Author(s):  
Munekazu Motoyama ◽  
Hiroki Iwasaki ◽  
Miyuki Sakakura ◽  
Takayuki Yamamoto ◽  
Yasutoshi Iriyama
Keyword(s):  
Size Distribution ◽  
Average Diameter ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
Uniform Size ◽  
Homogeneous Precipitation Method ◽  
Wide Range ◽  
Size Uniformity ◽  
Average Size ◽  
Uniform Size Distribution

Abstract This paper reports the synthesis of monodisperse spherical LiCoO2 particles in a wide range of average diameter using a urea-based-uniform-precipitation method. The average diameter of LiCoO2 particles can be varied from 2 to 14 lm with a uniform size distribution. The effective approach to maintain the size uniformity while changing the average size of LiCoO2 particles is to keep the ratio of [CO(NH2)2] to [CoSO4] at 8 even when the CoSO4 and urea concentrations are changed.

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