scholarly journals Recycling of Polypropylene/Polyethylene Blends: Effect of Chain Structure on the Crystallization Behaviors

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1456 ◽  
Author(s):  
Chuanchom Aumnate ◽  
Natalie Rudolph ◽  
Majid Sarmadi
Keyword(s):  
Mechanical Performance ◽  
Crystallization Rate ◽  
Chain Structure ◽  
Polymer Waste ◽  
Polyethylene Blends ◽  
Negative Effect ◽  
Unique Approach ◽  
Sorting Process ◽  
Branched Chain ◽  
Similar Density

The combination of high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polypropylene (PP) is frequently found in polymer waste streams. Because of their similar density, they cannot be easily separated from each other in the recycling stream. Blending of PP/ polyethylenes (PEs) in different ratios possibly eliminate the sorting process used in the regular recycling process. PP has fascinating properties such as excellent processability and chemical resistance. However, insufficient flexibility limits its use for specific applications. Blending of PP with relative flexible PEs might improve its flexibility. This is a unique approach for recycling or upcycling, which aims to maintain or improve the properties of recycled materials. The effects of the branched-chain structures of PEs on the crystallization behavior and the related mechanical properties of such blends were investigated. The overall kinetics of crystallization of PP was significantly influenced by the presence of PEs with different branched-chain structures. The presence of LDPE was found to decrease the overall crystallization rate while the addition of HDPE accelerated the crystallization process of the blends. No negative effect on the mechanical performance and the related crystallinity was observed within the studied parameter range.

scholarly journals Effect of Surfactant Molecular Structure on Emulsion Stability Investigated by Interfacial Dilatational Rheology

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1127
Author(s):  
Yuejie Jin ◽  
Dingrong Liu ◽  
Jinhua Hu
Keyword(s):  
Emulsion Stability ◽  
Chain Structure ◽  
Interfacial Film ◽  
Future Design ◽  
Rheological Method ◽  
Viscoelastic Modulus ◽  
Hydrophobic Chain ◽  
Branched Chain ◽  
The Stability ◽  
Branched Structure

Polyglycerol polyricinolate (PGPR) and polyglycerol-2 dioleate were selected as model surfactants to construct water-in-oil (W/O) emulsions, and the effect of interfacial rheological properties of surfactant film on the stability of emulsions were investigated based on the interfacial dilatational rheological method. The hydrophobicity chain of PGPR is polyricinic acid condensed from ricinic acid, and that of polyglycerol-2 dioleate is oleic acid. Their dynamic interfacial tensions in 15 cycles of interfacial compression-expansion were determined. The interfacial dilatational viscoelasticity was analyzed by amplitude scanning in the range of 1–28% amplitude and frequency sweep in the range of 5–45 mHz under 2% amplitude. It was found that PGPR could quickly reach adsorption equilibrium and form interfacial film with higher interfacial dilatational viscoelastic modulus to resist the deformation of interfacial film caused by emulsion coalescence, due to its branched chain structure and longer hydrophobic chain, and the emulsion thus presented good stability. However, polyglycerol-2 dioleate with a straight chain structure had lower interfacial tension, and it failed to resist the interfacial disturbance caused by coalescence because of its lower interfacial dilatational viscoelastic modulus, and thus the emulsion was unstable. This study reveals profound understanding of the influence of branched structure of PGPR hydrophobic chain on the interfacial film properties and the emulsion stability, providing experimental reference and theoretical guidance for future design or improvement of surfactant.

Kinetics of crystallization for polypropylene/polyethylene/halloysite nanotube nanocomposites

2018 ◽  
Vol 33 (4) ◽  
pp. 451-463 ◽  
Author(s):  
MY Ong ◽  
WS Chow
Keyword(s):  
Crystallization Rate ◽  
Avrami Equation ◽  
Crystallization Time ◽  
Halloysite Nanotube ◽  
Kissinger Equation ◽  
Polyethylene Blends ◽  
Instantaneous Nucleation ◽  
Half Crystallization Time ◽  
T Values ◽  
Kinetics Of

The aim of this study is to investigate the kinetics of non-isothermal crystallization of polypropylene/high-density polyethylene/halloysite nanotube (PP/HDPE/HNT) nanocomposites using three methods, that is, Avrami equation, combined Ozawa–Avrami method (hereafter called Mo model), and Kissinger equation. The Avrami exponent ( n) is in the range of 1–2 for all the PP/HDPE/HNT nanocomposites indicating instantaneous nucleation while the crystallization rate constant ( Zt) values of PP/HDPE increased with the addition of HNT. This proved that addition of HNT increases the crystallization rate. The reduction of half crystallization time ( t 1/2) for PP/HDPE as the increasing HNT loading indicates faster crystallization rate. In the Mo model, the cooling rate chosen at unit crystallization time F( T) values for PP/HDPE decreases with the addition of HNT. Kissinger equation showed that the activation energy ( E a) of crystallization for the PP/HDPE decreases with the addition of HNT. All the results demonstrated that HNT can accelerate the crystallization rate for the PP/polyethylene blends.

STUDIES ON REACTIONS RELATING TO CARBOHYDRATES AND POLYSACCHARIDES: LXI. PROPERTIES OF THE FRACTIONATED NITRATES OF TWO FRACTIONS OF CORN STARCH

1946 ◽  
Vol 24b (5) ◽  
pp. 246-253 ◽  
Author(s):  
W. R. Ashford ◽  
T. H. Evans ◽  
Harold Hibbert
Keyword(s):  
Relative Stability ◽  
Corn Starch ◽  
Chain Structure ◽  
Linear Type ◽  
Relative Stabilities ◽  
Preferential Adsorption ◽  
Chain Fraction ◽  
Branched Chain ◽  
Nitrogen Contents

Corn starch has been separated into two individual components, arbitrarily designated as amylose (linear fraction) and amylopectin (branched-chain fraction) by means of preferential adsorption on cellulose (Tanret–Pacsu method). These components have been nitrated and their nitrates fractionated by dissolution in ethanol. The relative stabilities and nitrogen contents of the nitrated fractions have been studied.Unfractionated amylose nitrate has greater stability than unfractionated amylopectin nitrate as judged by the Bergmann–Junk test. Dissolution methods of fractionation showed a much higher solubility of the amylopectin nitrate, the greater relative stability of the amylose fractions, and the somewhat greater stabilizing action of ethanol in the case of the latter.The widely different solubilities of amylose and amylopectin nitrates in conjunction with the lower ethanol solubility of whole starch nitrate are in accordance with the theory of a branched-chain structure for amylopectin and the linear type for amylose.

scholarly journals Mechanical Performance Under Various Conditions of 3D Printed Polylactide Composites With Natural Fibers

2021 ◽  
Author(s):  
Karolina E. Mazur ◽  
Aleksandra Borucka ◽  
Paulina Kaczor ◽  
Szymon Gądek ◽  
Stanislaw Kuciel
Keyword(s):  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Natural Fibers ◽  
Crystallization Rate ◽  
Mechanical Tests ◽  
Hydrothermal Degradation ◽  
3D Printed ◽  
The Impact ◽  
Different Levels ◽  
Additive Methods

Abstract In the study, polylactide-based (PLA) composites modified with natural particles (wood, bamboo, and cork) and with different levels of infilling (100%, 80%, and 60%) obtained by additive methods were tested. The effect of type fiber, infill level and crystallization rate on the mechanical properties were investigated by using tensile, flexural, and impact tests. The materials were subjected to mechanical tests carried out at 23 and 80 °C. Furthermore, hydrothermal degradation was performed, and its effect on the properties was analyzed. The addition of natural fillers and different level of infilling result in a similar level of reduction in the properties. Composites made of PLA are more sensitive to high temperature than to water. The decrease in Young's modulus of PLA at 80 °C was 90%, while after 28 days of hydrodegradation ~ 9%. The addition of fibers reduced this decrease at elevated temperatures. Moreover, the impact strength has been improved by 50% for composites with cork particles and for other lignocellulosic composites remained at the same level as for resin.

Chemiluminescence parameters of peroxynitrous acid in the presence of short-chain alcohols and Ru(bpy)32+

2011 ◽  
Vol 65 (6) ◽  
Author(s):  
Lijun Wei ◽  
Huifen Xia ◽  
Zhaopin Wang ◽  
Ping Yuan ◽  
Tong Zhou ◽  
...  
Keyword(s):  
Excited State ◽  
Carbon Chain ◽  
Chain Structure ◽  
Short Chain ◽  
Peroxynitrous Acid ◽  
Optimum Conditions ◽  
Chemiluminescence Intensity ◽  
Branched Chain

AbstractThe chemiluminescence behaviour and mechanism of peroxynitrous acid and Ru(bpy)32+ were studied in the presence of short-chain alcohols (methanol, ethanol, propan-1-ol, propan-2-ol, butanol, 2-methylpropan-1-ol, pentanol). It was found that the chemiluminescence intensity of peroxynitrous acid and Ru(bpy)32+ system could be significantly enhanced by these seven short-chain alcohols. The maximum chemiluminescence wavelength of 608 nm of [Ru(bpy)32+]* in the excited state was attributed to the reaction between Ru(bpy)32+ and dihydroxyalkyl radicals which were generated during the redox course of peroxynitrous acid and alcohols. In addition, the chemiluminescence signals of the system presented depended largely on the solubility and branched-chain structure as well as the length of carbon chain. The analytical characteristics and parameters of the peroxynitrous acid/Ru(bpy)32+/alcohols chemiluminescence system were investigated under optimum conditions.

scholarly journals Mechanical and Damping Properties of Recycled Aggregate Concrete Modified with Air-Entraining Agent and Polypropylene Fiber

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2004 ◽  
Author(s):  
Chonggang Zhou ◽  
Xingwang Pei ◽  
Wenlong Li ◽  
Yijun Liu
Keyword(s):  
Mechanical Performance ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Polypropylene Fiber ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Favorable Effect ◽  
Damping Properties ◽  
Aggregate Concrete ◽  
Negative Effect

In this study, recycled aggregate concrete (RAC) modified with polypropylene fiber (PP) and air-entraining agent (AGA) was prepared, and the effects of PP and AGA on the static (compressive strength, Young’s modulus, and splitting tensile strength) and dynamic properties (dynamic modulus of elasticity and damping ratio) of RAC were investigated. The experimental results showed that the addition of an AGA and PP had a favorable effect on the damping ratio of the concrete, however, the addition of the AGA had a slightly negative effect on the mechanical performance of the concrete. The AGA and PP contents required to achieve the optimum damping ratio of the concrete with the least reduction in the mechanical performance were 0.02% and 0.10%, respectively. Furthermore, the addition of AGA was more effective than that of PP in improving the damping property of the concrete.

Water absorption behavior of cellulosic fibres polymer composites: A review on its effects and remedies

2020 ◽  
pp. 152808372097442
Author(s):  
Parul Sahu ◽  
MK Gupta
Keyword(s):  
Water Absorption ◽  
Polymer Composites ◽  
Environmental Conditions ◽  
Mechanical Performance ◽  
Absorption Capacity ◽  
Effect Of Water ◽  
Negative Effect ◽  
Cellulosic Fibres ◽  
Kinetics Of ◽  
Positive Effect

Recently, researchers and scientists are trying to overcome the environmental burden by using biocomposites in engineering applications as far as possible. The main source of biocomposites is cellulosic fibres which is a class of natural fibres. Instead of many advantages of cellulosic fibres, they and their polymer composites suffer from some limitations as well. The environmental conditions are one of the most important issues to degradation behavior of the cellulosic fibres polymer composites (CFPCs). Among the environmental conditions, water absorption is an important ground to degradation in the mechanical performance of the CFPCs, which resists them to be used in outdoor applications. Several studies have been presented on water absorption characteristics of cellulosic fibres and its polymer-based biocomposites. Further, the consequence of water uptake on the mechanical performance of biocomposites was also reported in many studies. In most of the cases, a negative effect of water absorption was observed, whereas in a few cases a positive effect was also seen. In the present study, mechanics and kinetics of water absorption for CFPCs are discussed. Further, a detailed literature review on water absorption of cellulosic fibres and their different types of polymer-based biocomposites has also been carried out. Furthermore, studies reported on the effect of water absorption on the mechanical properties were also systematically presented. Moreover, all the possible remedies to lower the water absorption capacity were also discussed in the present review paper.

Recycling red mud from the production of aluminium as a red cement-based mortar

2017 ◽  
Vol 35 (5) ◽  
pp. 500-507 ◽  
Author(s):  
Xiaojie Yang ◽  
Jianfeng Zhao ◽  
Haoxin Li ◽  
Piqi Zhao ◽  
Qin Chen
Keyword(s):  
Red Mud ◽  
Mechanical Performance ◽  
Effective Management ◽  
Current Management ◽  
New Approach ◽  
Air Content ◽  
Negative Effect ◽  
Series Of Experiments ◽  
Hardened Properties ◽  
Performance Variations

Current management for red mud is insufficient and a new method is needed. A series of experiments have been carried out to develop a new approach for effective management of red mud. Mortars without or with 3%, 6% and 9% red mud were prepared and their fresh and hardened properties were measured to access the possibility of recycling the red mud in the production of red cement-based mortar. The mechanisms corresponding to their mechanical performance variations were explored by X-ray powder diffraction and scanning electron microscopy. The results show that the fresh mortars with red mud present an increase of viscosity as compared with the control. However, little difference is found when the content of red mud is altered. It also can be seen that red mud increases flow time and reduces the slump flow of the mortar. Meanwhile, it is found that mortar with red mud is provided with higher air content. Red mud is eligible to adjust the decorative mortar colour. Compressive strength of mortar is improved when less than 6% red mud is added. However, overall it has a slightly negative effect on tensile bond strength. It decreases the Ca(OH)2 content and densifies the microstructure of hardened paste. The heavy metal concentrations in leachates of mortars with red mud are much lower than the values required in the standard, and it will not do harm to people’s health and the environment. These results are important to recycle and effectively manage red mud via the production of red cement-based mortar.

Effect of Sodium Benzoate on the Crystallization Behavior of Poly (3-Hydroxybutyrate-Co-4-Hydroxybutyrate)

2014 ◽  
Vol 665 ◽  
pp. 375-378 ◽  
Author(s):  
Xiao Ping Wang ◽  
Wen Feng Li ◽  
Hao Zhang ◽  
De Ming Jia
Keyword(s):  
Activation Energy ◽  
Sodium Benzoate ◽  
Mechanical Performance ◽  
Crystallization Rate ◽  
Melt Crystallization ◽  
Crystalline Morphology ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Biodegradable Poly

Poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB), as the latest generation of biosynthesis and biodegradable Poly (β-hydroxyalkanoate) material, its mechanical performance is greatly improved while its application in industry is confined for the inadequate crystallization properties. The effect of sodium benzoate on P34HB’s crystallization behaviors and nucleation mechanism were investigated through differential scanning calorimetry (DSC) and Angle X-ray diffraction (WAXD). WAXD analysis indicated that the adding of sodium benzoate did not chang the crystalline morphology of P34HB. The analysis of the kinetic parameters including the activation energy (ΔEc) of the non-isothermal melt-crystallization were carried out, which demonstrated that both of the Mo crystallization rate parameter and the Kissinger activation energy value are found to be sharply dropped with the addition of sodium benzoate. Compared to pure P34HB, F(T) on 80 % crystallinity of P34HB with 0.25 phr sodium benzoate fell from 38.79 to 17.89, and ΔEc decreased from-63.1 KJ·mol-1 to-108.8 KJ·mol-1, which indicated that the application of sodium benzoate can obviously improve the crystallization rate of P34HB.

STRUCTURE OF A HEMICELLULOSE FROM MAPLE WOOD PREVIOUSLY EXTRACTED BY LIQUID AMMONIA

1957 ◽  
Vol 35 (4) ◽  
pp. 388-396 ◽  
Author(s):  
L. G. Neubauer ◽  
C. B. Purves
Keyword(s):  
Liquid Ammonia ◽  
Chain Structure ◽  
Hot Water ◽  
Wood Meal ◽  
Branched Chain ◽  
Conventional Study ◽  
Pectic Material

The extraction of maple wood meal with anhydrous liquid ammonia under pressure near 20° altered the wood in such a way that an additional small amount of lignin could be extracted with ethanol, and 1.9% of crude hemicelluloses with hot water. An additional 0.25% of nitrogen was retained, apparently as insoluble amides, by the residual wood. After elimination of pectic material by acetylation, the three subtractions of the hemicellulose acetate had identical specific rotations of −61 ± 1° in chloroform; all three corresponded in composition to a combination of one methylglucuronic anhydride to six anhydroxylose units. A conventional study by the methylation method suggested that the hemicellulose was a branched-chain structure averaging four anhydroxylose units linked 1—4, with one also substituted in the second position, and another linked 1—3.

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