Rubber-Curing Systems

Author(s):  
Rabin Datta
Keyword(s):  
2021 ◽  
Vol 395 (1) ◽  
pp. 2000258
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Klaudia Hložeková ◽  
Jarmila Vilčáková ◽  
Ivan Hudec

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3759 ◽  
Author(s):  
Xuejian Zhang ◽  
Lincai Ge ◽  
Yunlong Zhang ◽  
Jing Wang

Natural, standard, and compound curing are adopted to study the effect of different curing systems on the reinforcement of carbon fiber in reactive powder concrete (RPC). This work systematically studies the changes in RPC compressive and tensile strengths under different curing systems. Taking age, fiber content, and curing system as parameters, Scanning electron microscope (SEM) and X-ray diffraction (XRD) microscopic methods are used to study the influencing mechanism of carbon-fiber content and curing systems on RPC. The calculation methods of the RPC strength of different carbon-fiber contents are studied. Results show that the optimum carbon-fiber content of carbon-fiber RPC is 0.75% under the natural, standard, and compound curing conditions. In comparison with standard curing, compound curing can improve the early strength of carbon-fiber RPC and slightly affect the improvement of late strength. The strength is slightly lower in natural curing than in standard curing, but the former basically meets the requirements of the project and is beneficial for the practical application of this project. The calculation formula of 28-day compressive and splitting tensile strengths of carbon-fiber content from 0% to 0.75% is proposed to select the carbon-fiber content flexibly to satisfy different engineering requirements.


2019 ◽  
Vol 61 (6) ◽  
pp. 865-873
Author(s):  
Ján Kruželák ◽  
Elena Medlenová ◽  
Andrea Kvasničáková ◽  
Rastislav Dosoudil ◽  
Ivan Hudec ◽  
...  

Author(s):  
Anuradha Vitthal Wankhade ◽  
Sharad Basavraj Kamat ◽  
Santosh Irappa Hugar ◽  
Girish Shankar Nanjannawar ◽  
Sumit Balasaheb Vhate

Introduction: New generation composite resin materials have revolutionized the art of aesthetic dentistry. The clinical success is dependent on effective polymerisation and surface hardness which in turn are dependent on the performance of Light Curing Units (LCU). This study utilises surface hardness as a measure of degree of polymerisation of composite resins achieved by LCUs. Aim: To evaluate the difference in surface hardness of nanohybrid and microhybrid resin composites cured by light curing systems, Light Emitting Diode (LED) and Quartz Tungsten Halogen (QTH). Materials and Methods: In this invitro experimental study, two types of hybrid composites (Nanohybrid and Microhybrid) were tested for surface hardness by using two different light curing systems (LED and QTH). All the Nanohybrid and Microhybrid specimens were cured using LED and QTH LCUs, thus giving four combinations. A total of 60 specimens (6 mm diameter and 2 mm depth) were prepared using Teflon mould with 15 samples for each combination. Surface hardness was measured on upper and lower surface after 24 hours and hardness ratio was calculated. Data was analysed using independent t-test for intergroup comparison. Level of significance was kept at 5%. Results: Surface hardness of resin composites cured by LED LCU was greater than those cured by QTH LCU. Additionally, the hardness value was greater for the upper surface. Nanohybrids showed better surface hardness than Microhybrids for both the LCUs. Conclusion: Nanohybrid composite resins and LED system were found to be more effective in terms of surface hardness as compared to their counterparts.


2021 ◽  
pp. 009524432110386
Author(s):  
Mousumi De Sarkar ◽  
Takashi Sunada ◽  
Atsunori Kondo

The curing system plays a vital role in designing rubber compounds for various industrial applications. Therefore, it is paramount to establish viable curing strategies for any new elastomer to explore its application potentials and commercial significance. Impacts of different curing regimes on the properties of a recently developed copolymer of chloroprene and acrylonitrile (acrylonitrile-chloroprene rubber, NCR) are reported here. Several primary accelerators (four from thiourea- and one from thiazolene product families) were used for curing the new rubber along with fixed loadings of zinc oxide (5 phr) and magnesium oxide (4 phr). Besides, curatives based on sulfur and peroxide were also evaluated. The influence of different curing systems on the rheological and physical properties of the copolymer was explored. It has been seen that the properties of the copolymer are considerably influenced by the different curing systems used. While ethylene thiourea (ETU) and propylene thiourea (PTU), as primary accelerators, provide the highest state of cure but may cause scorch. The use of trimethyl thiourea (TMU), on the other hand, results in the fastest rate and the most stable state of cure, good scorch safety, bin stability, and an overall good balance of properties. The sulfur-based crosslinking system induces good mechanical properties but causes limited bin stability, poor high-temperature compression set, and impaired heat resistance properties. As a curing agent, peroxide delivers the best bin stability in the rubber stocks but yields higher stiffness and limited aging resistance in the vulcanizates.


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