Kinetics and Optimum Phenomenon of Vulcanization

1947 ◽  
Vol 20 (4) ◽  
pp. 933-937
Author(s):  
B. Dogadkin ◽  
B. Karmin ◽  
I. Golberg
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Point Of View ◽  
Sulfur Monochloride ◽  
Physical Chemical ◽  
Fundamental Process ◽  
Technical Properties ◽  
Kinetics Of ◽  
Homogeneous Reactions

Abstract The fundamental process of vulcanization consists in the combination of rubber with a vulcanizing agent : sulfur, sulfur monochloride, etc. The kinetics of this process may be expressed by monotonous curves. These may be interpreted either as the result of the heterogeneous character of the reaction or as the result of the combination of several homogeneous reactions. At the same time that the rubber combines with the vulcanizing agent, and largely as a consequence of this, a number of its physical-chemical and mechanical properties—solubility, density, tensile strength and other properties—undergo a change. These changes are extremely interesting from the technological point of view. In distinction to the kinetics of the combination of rubber with the vulcanizing agent, the kinetics of these processes can in most cases be represented by curves with a maximum or minimum. Thus, in the vulcanization of crude rubber, the tensile strength and modulus change according to a curve having a maximum; the solubility change follows a curve with a minimum. This character of the change experienced by the principal technical properties of the rubber determines the so-called “vulcanization optimum”. This term refers to that moment in the process of vulcanization when the particular property attains the necessary maximum or minimum, depending on the technical purposes of the vulcanizate.

scholarly journals A Robust, Tough and Multifunctional Polyurethane/Tannic Acid Hydrogel Fabricated by Physical-Chemical Dual Crosslinking

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 239 ◽  
Author(s):  
Jie Wen ◽  
Xiaopeng Zhang ◽  
Mingwang Pan ◽  
Jinfeng Yuan ◽  
Zhanyu Jia ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Polyethylene Glycol ◽  
Hydrogen Bonds ◽  
Tannic Acid ◽  
Hydroxyl Groups ◽  
Self Healing ◽  
Physical Chemical ◽  
Biomedical Field ◽  
Physical Crosslinking

Commonly synthetic polyethylene glycol polyurethane (PEG–PU) hydrogels possess poor mechanical properties, such as robustness and toughness, which limits their load-bearing application. Hence, it remains a challenge to prepare PEG–PU hydrogels with excellent mechanical properties. Herein, a novel double-crosslinked (DC) PEG–PU hydrogel was fabricated by combining chemical with physical crosslinking, where trimethylolpropane (TMP) was used as the first chemical crosslinker and polyphenol compound tannic acid (TA) was introduced into the single crosslinked PU network by simple immersion process. The second physical crosslinking was formed by numerous hydrogen bonds between urethane groups of PU and phenol hydroxyl groups in TA, which can endow PEG–PU hydrogel with good mechanical properties, self-recovery and a self-healing capability. The research results indicated that as little as a 30 mg·mL−1 TA solution enhanced the tensile strength and fracture energy of PEG–PU hydrogel from 0.27 to 2.2 MPa, 2.0 to 9.6 KJ·m−2, respectively. Moreover, the DC PEG–PU hydrogel possessed good adhesiveness to diverse substrates because of TA abundant catechol groups. This work shows a simple and versatile method to prepare a multifunctional DC single network PEG–PU hydrogel with excellent mechanical properties, and is expected to facilitate developments in the biomedical field.

scholarly journals Dynamic Cure Kinetics and Physical-Mechanical Properties of PEG/Nanosilica/Epoxy Composites

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Haleh Nowruzi Varzeghani ◽  
Iraj Amiri Amraei ◽  
Seyed Rasoul Mousavi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cure Kinetics ◽  
Diglycidyl Ether ◽  
Solid Particles ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Cure Kinetic ◽  
Cure Temperature ◽  
Kinetics Of

This study investigated the effect of polyethylene glycol (PEG) and nanosilica (NS) on the physical-mechanical properties and cure kinetics of diglycidyl ether of bisphenol-A-based epoxy (DGEBA-based EP) resin. For this purpose, tensile and viscometry tests, dynamic mechanical thermal analysis (DMTA), and differential scanning calorimetry (DSC) were carried out under dynamic conditions. The results showed that adding NS and PEG enhances the maximum cure temperature as well as the heat of cure reaction (ΔH) in EP-NS, while it decreases in EP-PEG and EP-PEG-NS. The cure kinetic parameters of EP-PEG-NS were calculated by Kissinger, Ozawa, and KSA methods and compared with each other. The Ea calculated from the Kissinger method (96.82 kJ/mol) was found to be lower than that of the Ozawa method (98.69 kJ/mol). Also, according to the KAS method, the apparent Ea was approximately constant within the 10-90% conversion range. Tensile strength and modulus increased by adding NS, while tensile strength diminished slightly by adding PEG to EP-NS. The glass transition temperature (Tg) was calculated using DMTA which was increased and decreased by the addition of NS and PEG, respectively. The results of the viscometry test showed that the viscosity increased with the presence of both PEG and NS and it prevented the deposition of solid particles.

scholarly journals The effect of drying on the mechanical properties and structure of biodegradable films

2018 ◽  
Author(s):  
Gabriela Silveira da Rosa ◽  
Sai Vanga ◽  
Yvan Gariepy ◽  
Vijaya Raghavan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Convective Drying ◽  
Vacuum Drying ◽  
Drying Rate ◽  
Biodegradable Films ◽  
Film Forming ◽  
Rate Period ◽  
Bovine Gelatin ◽  
Kinetics Of

The aim of this study was to investigate the effect of convective and vacuum drying on properties of biodegradable films. The film-forming solutions were prepared with bovine gelatin and carrageenan. The films solutions were dried in convective and vacuum dryers at temperatures of 40, 50 and 60 oC. The results of convective drying kinetics of biofilms showed a constant drying rate period followed by a falling drying rate period. The results of thickness showed dependence with moisture content present in films.Carrageenan films showed promising results, with high values of tensile strength and elongation for convective drying at 60 oC. Keywords: gelatin; carrageenan; drying; biofilm 

scholarly journals Experimental Researches on the Behavior of Polypropylene Pipes at the Physical-mechanical Testing

2019 ◽  
Vol 57 (2) ◽  
pp. 23-31
Author(s):  
Elena Valentina Stoian ◽  
Maria Cristiana Enescu ◽  
Ivona Camelia Petre ◽  
Ruxandra Elena Bratu ◽  
Vasile Bratu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Thermal Expansion ◽  
Basalt Fiber ◽  
Composite Fiber ◽  
Test Tube ◽  
Point Of View ◽  
Steel Pipes ◽  
Basaltic Fiber ◽  
Experimental Researches

Lately, PP-R pipes have become increasingly popular in terms of drinking water installations and heating. Comparated to the classic pipes from copper or steel, pipes from propylene are much easier to use, they have obvious qualities and they are marketed at a much lower price. The study aims a comparative analysis of the physical-mechanical properties of the four most common types of pipes from propylene, which are currently found in commerce : simple without insertion(PP-R), with insert of composite fiber (PP-R-CF), with insert of basalt fiber (PP-R-BF) and with insert of aluminium (PP-R-AIF). Experimental research showed that from the point of view of thermal expansion, the best behavior is from the pipes from propylene without any insert and the value of the thermal expansion coefficient for the reinforcement pipe with basaltic fiber is very small. After these attempts at tensile, it resulted that all four samples which were analyzed from the point of view of the tensile strength, don�t exceed the limit that was given by the manufacturer (10-30 MPa), the values obtained being: for pipe from polypropylene of 17 MPa, for pipe from polypropylene with insert of aluminium of 18 MPa, for the test tube from pipe of polypropylene with insert of basalt fiber of 29 MPa and for the test tube from pipe of polypropylene with insert of composite fiber of 30 MPa. Therefore, from the point of view of the behavior at tensile and bending, the best behavior is from the pipes from polypropylene with insert of basalt fiber and pipes from polypropylene with insert of composite fiber.

scholarly journals Analyze the effect of phosphorus on the mechanical properties and microstructure on cast iron

2018 ◽  
Vol 204 ◽  
pp. 05008
Author(s):  
Achmad Sambas ◽  
Ananto Gamawan ◽  
Sophiadi Gunara
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cast Iron ◽  
Mechanical Testing ◽  
Aluminum Electrolysis ◽  
Point Of View ◽  
Carbon Anode ◽  
Electrolysis Process ◽  
Microstructure Observation ◽  
Phosphorus Alloy

Cast Iron FC250 with phosphorus alloy is used as electrode connector in the aluminum electrolysis process at PT. Indonesia Asahan Aluminium (Inalum), that is used to connect the rod with carbon anode. It will be crushed after the carbon anode dimension is reduced, that takes approximately 30 days. In order to make crushing process easier, phosphorus alloy then added into such FC250. The objective of the study is determining phosphorus effect on FC 250. The methodology consists of determine the test specimens, initiate such specimen of casting by varying the amount of phosphorus percentage of 0.3%, 0.5%, 0.7% and 0.9%, then perform mechanical testing and microstructure observation on each specimen. The result is, as the percentage of phosphorus in FC 250 increased, so its hardness value whereas the value of the tensile strength even decreased. Form the microstructure point of view, the “steadit” increased as well in line with the rise of phosphorus.

scholarly journals Additives Incorporated in Cellulose Acetate Membranes to Improve Its Performance as a Barrier in Periodontal Treatment

2021 ◽  
Vol 2 ◽  
Author(s):  
Mariana Fornazier ◽  
Patricia Gontijo de Melo ◽  
Daniel Pasquini ◽  
Harumi Otaguro ◽  
Gabriela Ciribelli Santos Pompêu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cellulose Acetate ◽  
Physiological Solution ◽  
Point Of View ◽  
Lignin Concentration ◽  
Physical Chemical ◽  
Long Run ◽  
Cellulose Acetate Membranes ◽  
Sample Weight Loss ◽  
Calcium Glycerophosphate

In this study, we prepared cellulose acetate membranes, by means of casting mold, incorporated with two additives, sodium carboxymethyl lignin and calcium glycerophosphate, in order to improve properties for periodontal applications. The membranes were characterized from the morphological, structural, thermal and mechanical point of view, as well as by physiological pH tests. The results showed that membranes with additives improve the physical-chemical and mechanical properties, especially when the two additives are present in the same membrane, which can be attributed to the important synergy between them. The most significant effects occur in increasing the thickness and decreasing the density, which reflects in the porosity of the membranes, although the added amounts do not exceed 1.4%. A 1% increase in lignin concentration does not change the thickness and density of the membrane, but that amount of lignin plus 0.4% calcium glycerophosphate increases the thickness of the membrane by 42% and decreases the density by about 6%. Although there is a decrease in mechanical properties, as observed in Young's modulus and crystallinity, the significant and intermittent increase in sample weight loss with both additives in physiological solution indicates that, in the long run, it can be used as a degradable barrier.

scholarly journals A Study of the Mechanical Properties of Composite Materials with a Dammar-Based Hybrid Matrix and Two Types of Flax Fabric Reinforcement

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1649
Author(s):  
Dumitru Bolcu ◽  
Marius Marinel Stănescu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Composite Materials ◽  
Chemical Properties ◽  
Point Of View ◽  
Damping Factor ◽  
Hybrid Resin ◽  
Hybrid Matrix ◽  
Electron Microscopy Analysis ◽  
Specific Frequency

The need to protect the environment has generated, in the past decade, a competition at the producers’ level to use, as much as possible, natural materials, which are biodegradable and compostable. This trend and the composite materials have undergone a spectacular development of the natural components. Starting from these tendencies we have made and studied from the point of view of mechanical and chemical properties composite materials with three types of hybrid matrix based on the Dammar natural hybrid resin and two types of reinforcers made of flax fabric. We have researched the mechanical properties of these composite materials based on their tensile strength and vibration behavior, respectively. We have determined the characteristic curves, elasticity modulus, tensile strength, elongation at break, specific frequency and damping factor. Using SEM (Scanning Electron Microscopy) analysis we have obtained images of the breaking area for each sample that underwent a tensile test and, by applying FTIR (Fourier Transform Infrared Spectroscopy) and EDS (Energy Dispersive Spectroscopy) analyzes, we have determined the spectrum bands and the chemical composition diagram of the samples taken from the hybrid resins used as a matrix for the composite materials under study. Based on the results, we have suggested that these composite materials could be used in different fields of activity.

scholarly journals Preparation and Properties of Thermoplastic Polyurethane Composites Filled with Powdered Buckwheat Husks

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 356
Author(s):  
Marcin Włoch ◽  
Paulina Landowska
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Polymer Matrix ◽  
Chemical Structure ◽  
Low Cost ◽  
Thermoplastic Polyurethane ◽  
Thermomechanical Properties ◽  
Point Of View ◽  
Elongation At Break ◽  
Polyurethane Composites

Bio-based fillers for the polymer composites are still interesting from the scientific and industrial point of view, due to their low cost and renewable nature. In this work partially green composites were obtained by the mixing of thermoplastic poly(ester-urethane) with the unmodified and modified (by acetylation) grinded buckwheat husks. Obtained biocomposites were characterized in the terms of their chemical structure (FTIR), microstructure (SEM), thermal stability (TGA), thermomechanical properties (DMTA), and selected mechanical properties. The results showed that introduction of grinded buckwheat husks (even if the amount is 60 wt%) permit retaining high values of tensile strength (around 8–10 MPa), but the increasing amount of applied filler is connected with the decreasing of elongation at break. It can result from good interaction between the polymer matrix and the bio-based filler (confirmed by high values of polymer matrix-filler interaction parameter determined from Pukánszky’s model for the tensile strength of composites). The applied chemical treatment results in changing of mechanical properties of filler and composites. Obtained results confirmed the possibility of using powdered buckwheat husks as filler for thermoplastic polyurethane.

scholarly journals Processing and Properties of Fire Resistant EPDM Rubber-Based Ceramifiable Composites

2017 ◽  
Vol 36 (10) ◽  
pp. 963-969 ◽  
Author(s):  
Rafał Anyszka ◽  
Dariusz M. Bieliński ◽  
Zbigniew Pędzich ◽  
Magdalena Zarzecka-Napierała ◽  
Mateusz Imiela ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Point Of View ◽  
Rubber Matrix ◽  
Dicumyl Peroxide ◽  
Mineral Phase ◽  
Epdm Rubber ◽  
Optimal Amount ◽  
Point Temperature ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

AbstractLow softening point temperature glassy frit, reinforcing silica, wollastonite and dicumyl peroxide were incorporated into ethylene-propylene-diene (EPDM) rubber matrix in different amounts in order to obtain ceramifiable composites. Kinetics of vulcanization of the mixes was measured. Mechanical properties, micromorphology, thermal properties and combustibility of the vulcanizates were studied as well as compression strength of the ceramic residue obtained after heat treatment. Studies show that optimal amount of glassy frit from the point of view of ceramification effectiveness in dispersed mineral phase is 40 % wt.

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