Rise Of Curing Temperature Research Articles

Development of image analysis using Python: Relationship between matrix ratio of composite resin and curing temperature.

The aim of this study was to establish a measurement method for filler and matrix in cured resin composite (RC) using Python programming and to investigate the correlation between matrix ratio and curing temperature rise. Eight kinds of RCs were used. Backscattered electron images were taken for each cured specimen. Matrix and filler contents were calculated using Python programming with the K-means or area segmentation method. Volume measurement methods were assessed for comparison. Heat released during the polymerization reaction was measured. The matrix ratio was calculated without human intervention. Three specimens contained only inorganic filler, and other specimens contained multiple types of fillers. Almost the same values of the matrix ratio were obtained by programming and the volume measurement methods for specimens containing a single type of inorganic filler. Moreover, a strong correlation was found between the matrix ratio obtained by the programming method and curing temperature rise (R=0.9826).

Atomistic-scale insights into the crosslinking of polyethylene induced by peroxides

Dicumyl peroxide (DCP) is the most commonly used peroxide crosslinking agent for polyethylene (PE) in high voltage power cables. The DCP reactions in the PE matrix lead to the formation of a range of byproducts, some of which remain in the final crosslinked polyethylene (XLPE) product and may have adverse effects on the cable function and its long-term properties. In this study, we utilized ReaxFF based molecular dynamics (MD) simulations and experimental techniques including Fourier transform infrared (FTIR) mapping and wide-angle X-ray scattering (WAXS) to obtain detailed atomistic scale insight into peroxide-induced crosslinking of PE. Our results indicate that a moderate curing temperature rise to 500 K leads to an increased crosslinking extent, however, temperature rise above 500 K may have adverse effects on the PE crosslinking. Additionally, our results indicate that elevating the density improves the PE crosslinking. Our study showed that a high ratio of DCP to PE can increase the amount of generated byproducts but may not necessarily lead to an increased amount of XLPE. Our MD results also indicate that the presence of an external electric field had almost no effect on crosslinking and that di-(1-decyl-1-phenylundecyl) peroxide, may not be as efficient as DCP in XLPE production. These results indicate that ReaxFF based molecular dynamics, validated by experiments, is an efficient tool for analyzing – and improving – the conditions of polymerization chemistry.

The Effect of Cement Type and the Atmospheric Steam Curing Cycles on the Properties of Variable Types of Self-Compacting Lightweight Concrete

With the steam curing technology, effective fast curing technique in prefabrication technology, the effect of atmospheric steam curing on the mechanical properties of variable types of self-compacting lightweight concretes and the combination of the properties of semi-lightweight self-compacting concrete are important engineering approaches, focused in this study, in terms of workable and lightweight concrete production that is easy to apply. The cement type (CEM I 42.5 and CEM II 32.5) and three types of aggregates (normal, pumice and raw perlite) were the parameters of the study, including three types of steam curing cycle. The manufactured concrete samples were not only tested for compressive strength and bending, but also for splitting tensile strength. The fresh and hardened unit weight, dimension check and ultrasonic pulse velocity observations were also obtained for all 108 concrete samples. The three steam curing cycles were about 36.5 hours for 65°C, 70°C and 75°C. These steam-curing cycles were designed according to predesign tests and literature. As a result, the cement type and aggregate effect on the steam curing regimes were obtained. The decrease in the compressive strength of lightweight pumice concretes by the curing temperature rise and the negative effects of CEM II 32.5 on the strength values were the other striking results of the tests.

Study on Curing Temperature of Dry-Type Air-Core Reactor Based on Fiber Bragg Grating

干式空心电抗器的固化温升作为其生产流程中最关键环节之一，其环境温度的变化直接影响到干抗的匝间绝缘。本文结合厂家多年固化温升的经验，设计了一套基于Bragg光纤光栅的在线监测系统，该系统可对干式空心电抗器包封层的温度和应变进行在线测量。通过对干抗的现场固化温升实验的在线测量，得出了各包封层的温度和应变变化趋势。该研究成果将为变电站的干式空心电抗器实时监测提供重要的理论依据和设备支持。Curing temperature rise of dry-type air-core reactor is one of the most key links in the production process. The environment temperature changes directly affect the turn-to-turn insulation of dry resistance. In this paper, combining the manufacturers’ many years of experience of curing tem-perature rise, it designs a set of on-line monitoring system based on fiber Bragg grating. This sys-tem can do on-line measurement of dry-type air-core reactor temperature and strain of the coating layer. Through the online measurement of the curing temperature experiments of dry resistance, change trends of temperature and strain in each coating layer can be concluded. The results of the study will provide important theoretical basis and equipment support for the real-time monitoring of dry-type air-core reactor in transformer substation.

Initial fracture resistance and curing temperature rise of ten contemporary resin-based composites with increasing radiant exposure

ObjectivesThe principal objective of this study was to determine whether the bulk fracture resistance of ten light activated composites varied over a clinically realistic range of radiant exposures between 5 and 40J/cm2. MethodsTen operators were tested for clinically simulated radiant exposure delivery from a Bluephase® (Ivoclar Vivadent, Schaan, Liechtenstein) LED light to an occlusal cavity floor in tooth 27 in a mannequin head using a MARC®-Patient Simulator (Bluelight Analytics Inc., Halifax, NS) device. Notch disc test samples were prepared to determine the torque resistance to fracture (T) of the composites. Samples were irradiated with the same monowave Bluephase® light for 10s, 20s or 40s at distances of 0mm or 7mm. After 24h, storage samples were fractured in a universal testing machine and torque to failure was derived. ResultsRadiant exposure delivered in the clinical simulation ranged from 14.3% to 69.4% of maximum mean radiant exposure deliverable at 0mm in a MARC®-Resin Calibrator (Bluelight Analytics Inc., Halifax, NS) test device. Mean torque to failure increased significantly (P<0.05) with radiant exposure for 8 out of 10 products. The micro-fine hybrid composite Gradia Direct anterior (GC) had the lowest mean (S.D.) T between 10.3 (1.8)N/mm and 13.7 (2.2)N/mm over the tested radiant exposure range. Three heavily filled materials Majesty Posterior, Clearfil APX and Clearfil Photo-Posterior (Kuraray) had mean T values in excess of 25N/mm following 40J/cm2 radiant exposure. Mean T for Z100 (3MESPE) and Esthet-X (Dentsply) increased by 10% and 91% respectively over the tested range of radiant exposures. ConclusionsIndividual products require different levels of radiant exposure to optimize their fracture resistance. Light activated composites vary in the rate at which they attain optimal fracture resistance. Clinical significanceUnless the clinician accurately controls all the variables associated with energy delivery, there is no way of predicting that acceptable fracture resistance will be achieved intra-orally.

Artificial Neural Network and Nonlinear Models for Gelling Time and Maximum Curing Temperature Rise in Polymer Grouts

In this study, the effects of initial temperature, catalyst content, and activator content on the gelling time and maximum curing temperature of two polymeric grouts were investigated. Because the grouts are used in various environmental conditions, the grouts were investigated at three different initial temperatures (4.4, 15.7, and 26.7°C, or 40, 60, and 80°F). The catalyst and activator contents varied from 0.5% to 3% of the total weight of grout mix. Gelling times for the polymer grouts were measured, and the curing temperatures for the mixtures were monitored during and after the gelling process. The gelling time reduced with increased catalyst and activator contents and increased initial temperature for both the polymer grouts. One grout exhibited shorter gelling time and lower temperature rise during the gelling process than the other grout. Both artificial neural network (ANN) and nonlinear relationship (NLR) models were used to predict the observed grout behaviors. For each grout, a total of 48 tests were performed and data from 32 tests (2/3 of the total data) were used for training and calibrating the two models. The data from the 16 remaining tests were used to verify the model predictions. Various ANN architectures with numbers of hidden layers and neurons were studied to determine the optimum network architecture for the current study. The optimum network required two hidden layers with four nodes in each layer. The NLR model and the ANN model predicted the gelling time and maximum curing temperature rises very well, and the coefficient of determination (R2) was in the range of 0.91 to 0.97.