scholarly journals GTR/NBR/Silica Composites Performance Properties as a Function of Curing System: Sulfur versus Peroxides

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5345
Author(s):  
Łukasz Zedler ◽  
Xavier Colom ◽  
Javier Cañavate ◽  
Krzysztof Formela
Keyword(s):  
Mechanical Properties ◽  
Cross Linking ◽  
Organic Peroxides ◽  
Performance Properties ◽  
Acoustical Properties ◽  
Curing Characteristics ◽  
Link Density ◽  
Static Mechanical ◽  
Cross Link Density ◽  
Dispersive Silica

In this work, conventional sulfur and two types of organic peroxides (dicumyl peroxide (DCP) and di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB)) curing systems were used to investigate the possibility for tailoring of the performance properties of GTR/NBR blends reinforced with a variable content of highly dispersive silica (0–30 phr). The curing characteristics, static mechanical and acoustical properties, swelling behavior, thermal stability, and microstructure of the prepared composites were investigated. The results show that regardless of the curing system used, increasing the content of highly dispersive silica resulted in the improvement of the mechanical properties of the studied materials. It was observed that sulfur-based systems are the best choice in terms of cross-linking efficiency determined based on torque increment and cross-link density parameters. However, further analysis of the physico-mechanical properties indicated that the cross-linking efficiency does not match the performance of specimens, and the materials obtained using organic peroxides show higher tensile properties. This is due to the improved physical interactions between the GTR/NBR matrix and highly dispersive silica when using peroxide systems. It was confirmed using the analysis of the Wolff activity coefficient, indicating the enhanced synergy.

PEG Cross-Linked Alginate Hydrogels with Controlled Mechanical Properties

1998 ◽  
Vol 530 ◽  
Author(s):  
Petra Eiselt ◽  
Jon A. Rowley ◽  
David J. Mooney
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Molecular Weight ◽  
Elastic Modulus ◽  
Cell Transplantation ◽  
Cross Linking ◽  
Cross Link ◽  
Link Density ◽  
A Cell ◽  
Cross Link Density

AbstractReconstruction of tissues and organs utilizing cell transplantation offers an attractive approach for the treatment of patients suffering from organ failure or loss. Highly porous synthetic materials are often used to mimic the function of the extracellular matrix (ECM) in tissue engineering, and serve as a cell delivery vehicle for the formation of tissues in vivo. Alginate, a linear copolysaccharide composed of D-mannuronic acid (M) and L-guluronic acid (G) units is widely used as a cell transplantation matrix. Alginate is considered to be biocompatible, and hydrogels are formed in the presence of divalent cations such as Ca2+, Ba2+ and Sr2+. However, ionically cross-linked alginate gels continuously lose their mechanical properties over time with uncontrollable degradation behavior. We have modified alginate via covalent coupling of cross-linking molecules to expand and stabilize the mechanical property ranges of these gels. Several diamino PEG molecules of varying molecular weight (200, 400, 1000, 3400) were synthesized utilizing carbodiimide chemistry. Sodium alginate was covalently cross-linked with these cross-linking molecules, and mechanical properties of the resulting hydrogels were determined. The elastic modulus of the cross-linked alginates depended on the molecular weight of the cross-linking molecules, and ranged from 10-110 kPa. The theoretical cross-link density in the hydrogels was also varied from 3 to 47% (relative to the carboxylic groups in the alginate) and the mechanical properties were measured. The elastic modulus increased gradually and reached a maximum at a cross-link density of 15%. In summary, covalently coupled hydrogels can be synthesized which exhibit a wide range of mechanical properties, and these materials may be useful in a number of tissue engineering applications.

scholarly journals Application of Peroxide Curing Systems in Cross-Linking of Rubber Magnets Based on NBR and Barium Ferrite

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Elena Medlenová ◽  
Rastislav Dosoudil ◽  
Ivan Hudec
Keyword(s):  
Mechanical Properties ◽  
Barium Ferrite ◽  
Cross Linking ◽  
Butadiene Rubber ◽  
Cross Link ◽  
System Composition ◽  
Peroxide Curing ◽  
Link Density ◽  
Cross Link Density ◽  
Curing Systems

Rubber magnetic composites were prepared by incorporation of barium ferrite in constant amount—50 phr into acrylonitrile-butadiene rubber. Dicumyl peroxide as the curing agent was used for cross-linking of rubber magnets alone, or in combination with four different types of co-agents. The main aim was to examine the influence of curing system composition on magnetic and physical-mechanical properties of composites. The cross-link density and the structure of the formed cross-links were investigated too. The results demonstrated that the type and amount of the co-agent had significant influence on cross-link density, which was reflected in typical change of physical-mechanical properties. The tensile strength increased with increasing amount of co-agents, which can be attributed to the improvement of adhesion and compatibility on the interphase filler-rubber due to the presence of co-agents. Magnetic characteristics were found not to be influenced by the curing system composition. The application of peroxide curing systems consisting of organic peroxide and co-agents leads to the preparation of rubber magnets with not only good magnetic properties but also with improved physical-mechanical properties, which could broaden the sphere of their application uses.

Production and properties of natural rubber glove using sustainable benign accelerator

2021 ◽  
pp. 147776062110194
Author(s):  
Vishantini Tangavaloo ◽  
Nor Yuliana Yuhana ◽  
Yu Lih Jiun
Keyword(s):  
Mechanical Properties ◽  
Manufacturing Industry ◽  
Maturation Time ◽  
Curing Characteristics ◽  
Link Density ◽  
Cross Link Density ◽  
And Performance ◽  
Time Required ◽  
Stability Results ◽  
Selection Of

In natural polyisoprene glove manufacturing industries, the selection of accelerators in the curing system is mainly determined by the curing characteristics, maturation time required, cross-link density and mechanical properties of gloves. In this study, a new accelerator replacing conventional ones in a typical glove manufacturing process, was studied in order to produce free carcinogen dipped article. The glove properties and performance prepared by using both conventional and new proposed accelerators were studied and compared. The use of a conventional accelerator tends to release carcinogenic chemicals namely N-nitrosamine and N-nitrosatable substances. These chemicals are restrained on dipped articles under the requirement of EN 71-12:2013. Xanthogen accelerators promote the reduction of carcinogenic chemicals, but they are associated with prolonged maturation hour, which is unfavourable in the manufacturing industry. This study used a mixture of a benign accelerator, namely, diisononyldithiocarbamate and diisopropyl xanthogen polysulfide, to substitute the usage of conventional accelerators zinc dibutyl dithiocarbamate and zinc diethyl dithiocarbamate. The effects of benign accelerator loading in latex compounds were studied by focusing on the swelling index, maturation hour, carcinogenic chemical released and mechanical properties, thermal degradation and stability. Results showed no presence of N-nitrosamines and N-nitrosatable substances in the final dipped products by using 0.3 and 0.5 phr of benign accelerator. This study showed that 0.5 phr of benign accelerator achieved a moderate pre-vulcanising rate and improved the pre-ageing tensile strength and elongation by 11% and 7.0%, respectively. Moreover, its thermal stability was higher and discolouration intensity was lower as compared with the conventional accelerator.

Boron nitride for modification of rubber based on isoprene elastomer

2020 ◽  
pp. 105-112
Author(s):  
K. S. Zhansakova ◽  
E. N. Eremin ◽  
G. S. Russkikh ◽  
O. V. Kropotin
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Gradual Increase ◽  
Physical And Mechanical Properties ◽  
Curing Time ◽  
Cross Link ◽  
Start Time ◽  
Link Density ◽  
Cross Link Density ◽  
Isoprene Rubber

The work studies vulcanization characteristics of elastomers based on isoprene rubber filled with carbon black N330 and boron nitride (BN). The influence of the boron nitride (BN) concentration on technological, dynamic, physical and mechanical properties of elastomers has been researched. The application of boron nitride for producing rubber with good properties has been considered. With a gradual increase of the inert filler BN concentration up to 35%, a decrease in the curing rate by 33% and polymer cross-link density by 26% is observed. Moreover, the start time of vulcanization increases by almost 300%, the optimal curing time by 200%.

Mechanical and structural consequences of associative dynamic cross-linking in acrylic diblock copolymers

2021 ◽  
Author(s):  
Jacob Ishibashi ◽  
Ian Pierce ◽  
Alice Chang ◽  
Aristotelis Zografos ◽  
Bassil El-Zaatari ◽  
...  
Keyword(s):  
Viscoelastic Properties ◽  
Diblock Copolymers ◽  
Microphase Separation ◽  
Network Connectivity ◽  
Ethyl Acrylate ◽  
Cross Linking ◽  
Cross Link ◽  
Block Polymers ◽  
Link Density ◽  
Cross Link Density

<p>The composition of low-T<sub>g</sub> <i>n</i>-butylacrylate-<i>block</i>-(acetoxyaceto)ethyl acrylate block polymers is investigated as a strategy to tune the properties of dynamically cross-linked vinylogous urethane vitrimers. As the proportion of the cross-linkable block is increased, the thermorheological properties, structure, and stress relaxation evolve in ways that cannot be explained by increasing cross-link density alone. Evidence is presented that network connectivity defects such as loops and dangling ends are increased by microphase separation. The thermomechanical and viscoelastic properties of block copolymer-derived vitrimers arise from the subtle interplay of microphase separation and network defects.</p><div><br></div><p></p>

scholarly journals Structural and Thermo-Mechanical Properties of Poly(ε-caprolactone) Modified by Various Peroxide Initiators

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1101 ◽  
Author(s):  
Przybysz ◽  
Hejna ◽  
Haponiuk ◽  
Formela
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Cross Linking ◽  
Mechanical And Thermal Properties ◽  
Dicumyl Peroxide ◽  
Organic Peroxides ◽  
Reactive Processing ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Gel Fraction

The modification of poly(ε-caprolactone) (PCL) was successfully conducted during reactive processing in the presence of dicumyl peroxide (DCP) or di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB). The peroxide initiators were applied in the various amounts of 0.5 or 1.0 pbw (part by weight) into the PCL matrix. The effects of the initiator type and its concentration on the structure and mechanical and thermal properties of PCL were investigated. To achieve a detailed and proper explication of this phenomenon, the decomposition and melting temperatures of DCP and BIB initiators were measured by differential scanning calorimetry. The conjecture of the branching or cross-linking of PCL structure via used peroxides was studied by gel fraction content measurement. Modification in the presence of BIB in PCL was found to effectively increase gel fraction. The result showed that the cross-linking of PCL started at a low content of BIB, while PCL modified by high DCP content was only partially cross-linked or branched. PCL branching and cross-linking were found to have a significant impact on the mechanical properties of PCL. However, the effect of used initiators on poly(ε-caprolactone) properties strongly depended on their structure and content. The obtained results indicated that, for the modification towards cross-linking/branching of PCL structure by using organic peroxides, the best mechanical properties were achieved for PCL modified by 0.5 pbw BIB or 1.0 pbw DCP, while the PCL modified by 1.0 pbw BIB possessed poor mechanical properties, as it was related to over cross-linking.

Elongation at Break as a Measure of Cross-Link Density in Vulcanized Elastomers

1966 ◽  
Vol 39 (3) ◽  
pp. 726-739 ◽  
Author(s):  
E. DiGiulio ◽  
G. Bellini ◽  
G. V. Giandinoto
Keyword(s):  
Crosslink Density ◽  
Cross Linking ◽  
Total Degree ◽  
Cross Link ◽  
Elongation Ratio ◽  
Elongation At Break ◽  
Ethylene Propylene ◽  
First Approximation ◽  
Link Density ◽  
Cross Link Density

Abstract After recalling the reaction mechanism suggested for the crosslinking of ethylene propylene copolymers with organic peroxides, the authors consider the relation between concentration of curing agent and crosslink density. It is experimentally found that, as a first approximation, the elongation ratio at break of vulcanizates (unfilled or filled with small quantities of carbon black) is a function of molar concentration of peroxide only: αR=K/P1/2 This relation can be theoretically justified on the basis of the extensibility of polymer chain segments and of the criterion for rupture originally put forward by Taylor and Darin. By applying the above relation to ethylene propylene copolymers it is possible to evaluate the influence of the chain-splitting reaction during cross-linking. The reciprocal of the square of elongation ratio at break (1/αR2) measures the total degree of crosslinking.

Effect of curing systems on vulcanization, mechanical properties, and stress softening of hydrogenated nitrile butadiene rubber vulcanizates

2016 ◽  
Vol 49 (3) ◽  
pp. 243-257 ◽  
Author(s):  
Jianhua Guo ◽  
Zhicai Li ◽  
Xin Zhang
Keyword(s):  
Mechanical Properties ◽  
Dissipated Energy ◽  
Butadiene Rubber ◽  
Stress Softening ◽  
Cyclic Compression ◽  
Nitrile Butadiene Rubber ◽  
Link Density ◽  
Cross Link Density ◽  
Number Of Cycles ◽  
Curing Systems

Hydrogenated nitrile butadiene rubber (HNBR) is cured by sulfur (S), dicumyl peroxide (DCP), and S donor, respectively. Effect of curing systems on vulcanization, mechanical properties, and cyclic compression of HNBR vulcanizates was investigated. The dependence of storage modulus ( G′) on strain was evaluated by Rubber Processing Analysis (RPA) analysis. The Mullins effect and degree of stress softening were also investigated by cyclic compression test. The energy dissipation of cyclic compression was calculated. The presumed mechanism of stress softening of HNBR was presented. The results show that the curing speed, torque, and G′ are higher for S curing system compared with DCP and S donor. The elongation of break and hardness for S system are higher than that of DCP and S donor. The maximum compressive stress, stress softening, and dissipated energy decreased with the increasing number of cycles. The degree of stress softening for S is lower due to the bigger cross-link density and stronger filler–rubber interaction in S-cured HNBR.

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