A Study on Thermal and Electrical Conductivities of Ethylene-Butene Copolymer Composites with Carbon Fibers

Ethylene-butene copolymer (EBC)/carbon-fiber (CF) composites can be utilized as an electromechanical material due to their ability to change electric resistance with mechanical strain. The electro-mechanical properties and thermal conductivity of ethylene butene copolymer (EBC) composites with carbon fibers were studied. Carbon fibers were introduced to EBC with various concentrations (5 to 25 wt%). The results showed that carbon fibers’ addition to EBC improves the electric conductivity up to 10 times. Increasing the load up to 2.9 MPa will raise the electric resistance change by 4 500% for a 25% fiber sample. It is also noted that the EBC/CF composites’ electric resistance underwent a dramatic increase in raising the strain. For example, the resistance change was around 13 times higher at 15% strain compared to 5% strain. The thermal conductivity tests showed that the addition of carbon fibers increases the thermal conductivity by 40%, from 0.19 to 0.27 Wm–1K–1.

Evaluation of the survivability of CFRP honeycomb-cored panels in compression after impact tests

This paper is oriented to the experimental research of the mechanics of the CFRP sandwich plates, glass and carbon fiber sample panels with a large-cell honeycomb core. The method for testing polymer composite sample plates in compression after impact (CAI) tests with joint use of a testing machine and a video system for deformation field registration was tested. Analysis of the experimental data obtained highlighted the impactive sensitivity zone for the test specimens. A quantitative assessment of the load-bearing capacity of glass and carbon fiber sample panels in CAI tests with the different levels of the drop weight impact energy was performed. Photos of samples after impact have been provided. Vic-3D non-contact three-dimensional digital optical system was used to register the displacement and deformation fields on the surface of the samples. The video system was used to evaluate various damage mechanisms, including matrix cracking, delaminations, and rupture of the damaged fibers. The paper studied the evolution of non-homogeneous deformation fields on the surface of the composite samples during the post-impact compression tests and analyzed the configuration of non-homogeneous deformation fields.

Determination of the strength and elongation distribution of single wool through fiber bundle testing based on acoustic emissions

The method to obtain the breaking strength and elongation distribution of fiber through numerous single fiber tests is tedious and time-consuming. In the present work, a method based on acoustic emission (AE) signals generated by fiber fracture during the fiber bundle test has been developed for estimating the distribution of single wool breaking strength and elongation. AE detection is performed simultaneously during the fiber extension. According to the AE signal, it is proved that every individual fiber break can be detected, and the failure probability distribution of wool elongation can be obtained. Based on this, the single wool breaking strength is estimated from the tensile response of the fiber bundle, and then its distribution can be deduced. Finally, the distributions of breaking strength and elongation determined by the bundle test are compared with that obtained from the single fiber samples. The results show that the method developed in this work can be used to estimate the breaking strength and elongation of the single fiber within the bundle. Their cumulative probability distributions are similar to the results of single fiber sample tests, especially the distribution of the breaking strength.

A Study on Thermal and Electrical Conductivities of Ethylene-Butene Copolymer Composites with Carbon Fibers

The electrical, mechanical and thermal conductivity of ethylene butene copolymer (EBC) composites with carbon fibers were studied. EBC/carbon-fiber composites can be utilized as an electro-mechanical material which is capable of changing it electric resistance with mechanical strain. Carbon fibers were introduced to EBC with different concentrations (5-25 wt%). The results showed that the addition of carbon fibers to EBC could increase the electric resistance up to 10 times. Increasing the load to 2.9 MPa could increase the electric resistance change by 4500% compared 25% fiber sample with pure EBC. It is also noted that the electric resistance of the EBC/CF composites underwent a dramatic increase with raising the strain, for example, the resistance change was around 13 times more at 15% strain in comparison to 5% of strain; The thermal conductivity tests showed that the addition of carbon fibers could increase the thermal conductivity by 40%, from 0.19 to 0.27 (Wm-1K-1). It was also observed that the addition of carbon fibers to EBC could increase the thermal conductivity.

Вычислительный эксперимент по моделированию распространения света в волокнистой профилированной структуре

Many studies show that profiled structures are the source of attaining desired system characteristics in industrial or other applications. In this short note, we continue considering proposed recently by us the profiled structure such as a beach umbrella based on the principles of origami design. To demonstrate the optical properties of the given model, a developed recursive ray tracing algorithm is used to simulate the propagation of light rays through the modelled paper fiber sample. In this paper, modeling light propagation through a porous structure using ray tracing technique is presented and results of modeling light propagation in a profiled structure with respect to simulated light propagation in fiber structure are discussed. Во многих работах указывается, что использование профилированных структур позволяет получить характеристики материала, необходимые для его применения в промышленности и других областях. В этой небольшой статье мы продолжаем рассматривать предложенную нами недавно профилированную структуру в виде пляжного зонта, основанную на принципах дизайна оригами. Для демонстрации оптических свойств данной модели используется разработанный алгоритм рекурсивной трассировки лучей для моделирования распространения световых лучей через смоделированный образец бумажного волокна. В этой статье представлено моделирование распространения света через пористую структуру с использованием техники трассировки лучей, а также обсуждаются результаты моделирования распространения света в профилированной структуре в сравнении с моделированным распространением света в волокнистой структуре.

Enzymatic hydrolysis (pepsin) assisted by ultrasound in the functional Properties of hydrolyzates from different collagens

ABSTRACT: Enzymatic hydrolysis (pepsin) assisted with or without ultrasound in the functional properties of hydrolyzates from different collagens were analyzed. Degree of hydrolysis, antioxidant activity (DPPH) and antimicrobial activity (MIC) were assessed. The treatment that resulted in greater antioxidant activity for the fiber sample was with the use of 4% of enzyme and concomitant ultrasound (40.7%), leading to a degree of hydrolysis of 21.7%. For the powdered fiber sample the hydrolysis treatment with use of 4% of enzyme resulted in lower protein content (6.97mg/mL), higher degree of hydrolysis (19.9%) and greater antioxidant activity (38.6%). The hydrolyzates showed inhibitory capacity against gram-negative bacteria Salmonella choleraesuis and gram-positive bacteria Staphylococcus aureus. It can be concluded that enzymatic hydrolysis concomitant or not with the use of ultrasound increased the functionality of the fiber and powdered fiber samples, for the other samples its use as supplementary treatment was not productive, due to the worse results of antioxidant activity (DPPH) reported. However, it provided greater hydrolysis degree.

High electrical conductivity of double-walled carbon nanotube fibers by hydrogen peroxide treatments

H2O2treatment can decrease the electrical resistivity of double walled carbon nanotube fibers. The experimental observations suggest that small diameter carbon nanotubes are removed from the fiber sample.

Study on Rapid Wool Shrinkproof Method Based on Protease Treatment

In the current work, the objective of shrinkproof wool was rapidly achieved via the synergetic effect between a protease and its bioenzyme activator, dramatically increasing the reaction rate of protease to wool cuticles. Optimal shrinkproof effect was obtained after the wool fiber sample was processed in the enzymatic solution for 3min at 50°C under the optimized treating condition, i.e, the concentrations of protease and enzyme activator were 1.3g/L and 2.5g/L respectively, with the wet pickup ratio of 130%, the resultant wool sample maintained 82% and 80% of its control sample in terms of tenacity and extension @ break, respectively, which meets the requirements for subsequent processing and applications. Further large-scale protease treatment to wool yarns was performed and the test result for shrinkage rate was-3.01% based on the shrinkproof standard test method of IWS TM31(5A×5), indicating satisfactory wool shrinkproof effect at rapid processing rate (7m/min).