Effect of Accelerated Ageing on the Mechanical and Structural Properties of the Material System Used in Protectors

Currently, there is a wide range of materials for motorcyclists available on the market that have a significant ability to absorb impact energy. Understanding the aging processes of materials is crucial for guaranteeing the long-term durability and safety of a new product. For this reason, the effect of accelerated aging on the mechanical and structural properties of the multifunctional materials used in commercial protectors was analyzed. The accelerated aging considered in this study simulated 3 years of use under real conditions. Then, DMTA and FT-IR research, as well as impact tests, were carried out on the commercially available protectors for motorcyclists, before and after the accelerated aging processes. Structural analysis using FT-IR showed no significant changes in the structure of the polymers used for producing the protectors. The DMA test results are consistent with those obtained from the impact study. Both methods showed that the samples maintain their protective properties, after accelerated aging. All of the examined protectors show that an increase in force is transferred through the sample, after the accelerated aging processes, but they still provide protection, according to the ISO standard.

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Artificial and Natural Aging of Polypropylene Used in Passenger Vehicle Bumpers

Materiale Plastice ◽

10.37358/mp.21.2.5492 ◽

2021 ◽

Vol 58 (2) ◽

pp. 201-210

Author(s):

Hongshen Zhang ◽

Hongfei Zheng

Keyword(s):

Accelerated Aging ◽

Natural Aging ◽

Short Term ◽

Uv Aging ◽

Accelerated Aging Test ◽

Aging Test ◽

Wide Range ◽

Aging Properties ◽

Materials Used ◽

The Impact

Polypropylene (PP) has a wide range of applications in the automobile bumpers due to its many excellent properties. Mechanical properties of PP for automobile bumpers are investigated through an artificial accelerated aging test. The aging rules after different years of normal use and the artificial accelerated aging test are analyzed. The correlation between natural and artificially accelerated aging is also explored. It provides a reference for the study of the aging properties of polymers for automotive applications. Results show that the UV aging test can effectively simulate changes in tensile and bending strengths after natural aging and can be used to evaluate the weathering resistance of PP materials used in automotive bumpers. The tensile and bending strengths of these materials remain good during aging, and elongation is sensitive to aging. The short-term artificial accelerated aging test does not exert a significant influence on the impact strength of materials, and artificial accelerated aging does not completely reproduce the aging process of the material.

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Analysis of the Impact on the Mechanical Properties of Modification of Oligohydroxyethers in Organic Solvent Solution with Rubbers

Polymers ◽

10.3390/polym13040519 ◽

2021 ◽

Vol 13 (4) ◽

pp. 519

Author(s):

Vitalii Bezgin ◽

Agata Dudek ◽

Adam Gnatowski

Keyword(s):

Mechanical Properties ◽

Scientific Paper ◽

Styrene Butadiene Rubber ◽

Butadiene Rubber ◽

Molecular Weights ◽

Wide Range ◽

Strength Tests ◽

Materials Used ◽

Styrene Butadiene ◽

The Impact

This paper proposes and presents the chemical modification of linear hydroxyethers (LHE) with different molecular weights (380, 640, and 1830 g/mol) with the addition of three types of rubbers (polysulfide rubber (PSR), polychloroprene rubber (PCR), and styrene-butadiene rubber (SBR)). The main purpose of choosing this type of modification and the materials used was the possibility to use it in industrial settings. The modification process was conducted for a very wide range of modifier additions (rubber) per 100 g LHE. The materials obtained in the study were subjected to strength tests in order to determine the effect of the modification on functional properties. Mechanical properties of the modified materials were improved after the application of the modifier (rubber) to polyhydroxyether (up to certain modifier content). The most favorable changes in the tested materials were registered in the modification of LHE-1830 with PSR. In the case of LHE-380 and LHE-640 modified in cyclohexanol (CH) and chloroform (CF) solutions, an increase in the values of the tested properties was also obtained, but to a lesser extent than for LHE-1830. The largest changes were registered for LHE-1830 with PSR in CH solution: from 12.1 to 15.3 MPa for compressive strength tests, from 0.8 to 1.5 MPa for tensile testing, from 0.8 to 14.7 MPa for shear strength, and from 1% to 6.5% for the maximum elongation. The analysis of the available literature showed that the modification proposed by the authors has not yet been presented in any previous scientific paper.

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‘If a fight starts, watch the crowd’: The effect of violence on popular support for social movements

Journal of Peace Research ◽

10.1177/0022343318820575 ◽

2019 ◽

Vol 56 (4) ◽

pp. 485-498 ◽

Cited By ~ 4

Author(s):

Jordi Muñoz ◽

Eva Anduiza

Keyword(s):

Social Movements ◽

Causal Effect ◽

The Other ◽

Popular Support ◽

Face To Face ◽

Percentage Points ◽

Street Violence ◽

Wide Range ◽

Before And After ◽

The Impact

Social movements often face tactic diversification. In otherwise nonviolent movements, some groups or radical flanks may resort to violent actions such as street rioting. This article analyzes the impact that these violent episodes can have on popular support for the movement as a whole. To estimate the causal effect of violence, it exploits an unexpected riot outbreak that occurred during the fieldwork of a face-to-face survey in Barcelona in May 2016, led by a squat group linked to the anti-austerity movement known as the 15-M or indignados that emerged during the financial crisis. By comparing respondents interviewed before and after the riots, it finds that the street violence episode reduced support for the 15-M movement by 12 percentage points on average. However, the magnitude of the effect is highly conditional on the respondents’ predispositions towards the movement. Core supporters, that are expected to share the frame of the movement in justifying violent actions, are the least affected by the violent outbreak. On the other extreme, weak supporters, opposers, and non-aligned citizens reduce their support to a larger extent. Results are robust to different specifications and a wide range of robustness checks. These findings have potentially important implications for movements concerned with broadening their support base.

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Understanding the Equity Consequences of School-Finance Reform

Harvard Educational Review ◽

10.17763/haer.48.2.06652lv504715u13 ◽

1978 ◽

Vol 48 (2) ◽

pp. 193-226 ◽

Cited By ~ 10

Author(s):

Lee Friedman ◽

Michael Wiseman

Keyword(s):

New York ◽

School Finance ◽

Finance Reform ◽

School Finance Reform ◽

Wide Range ◽

Before And After ◽

School Financing ◽

Empirical Tests ◽

The Impact

In this essay, Lee S. Friedman and Michael Wiseman discuss the economic, legal,and logical implications of school-financing methods now practiced in several states, including Illinois, New York, and California. Examining the Serrano case in California, the authors contend that an important inconsistency in the court requirements resulted from the apparent failure of both the courts and the legislatures to specify the logical relationships between several competing concepts of equality. To this end, Friedman and Wiseman provide a logical analysis of several concepts needed to measure the fair distribution of school revenues and resources. Using Illinois as a case study, they then construct empirical tests for each of those concepts both before and after the Hoffman-Fawell reform in school financing. Those data, finally, are used to suggest an analytic framework that can be employed for evaluating and perhaps predicting the impact of school-finance reforms on a wide range of state systems.

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Contribution of a Winged Phlebotomy Device Design to Blood Splatter

Infection Control and Hospital Epidemiology ◽

10.1086/668030 ◽

2012 ◽

Vol 33 (11) ◽

pp. 1069-1076 ◽

Cited By ~ 3

Author(s):

Donna J. Haiduven ◽

Christine McGuire-Wolfe ◽

Shawn P. Applegarth

Keyword(s):

Human Subjects ◽

Healthcare Personnel ◽

Device Design ◽

Wide Range ◽

Before And After ◽

Intravascular Devices ◽

Ocular Exposure ◽

Injury Protection ◽

Sharps Injury ◽

The Impact

Background.Despite a proliferation of phlebotomy devices with engineered sharps injury protection (ESIP), the impact of various winged device designs on blood splatter occurring during venipuncture procedures has not been explored.Objectives.To evaluate the potential for blood splatter of 6 designs of winged phlebotomy devices.Design.A laboratory-based device evaluation without human subjects, using a simulated patient venous system.Methods.We evaluated 18 winged phlebotomy devices of 6 device designs by Terumo, BD Vacutainer (2 designs), Greiner, Smith Medical, and Kendall (designated A-F, respectively). Scientific filters were positioned around the devices and weighed before and after venipuncture was performed. Visible blood on filters, exam gloves, and devices and measurable blood splatter were the primary units of analysis.Results.The percentages of devices and gloves with visible blood on them and filters with measurable blood splatter ranged from 0% to 20%. There was a statistically significant association between device design and visible blood on devices (P< .0001) and between device design and filters with measurable blood splatter (P< .0001), but not between device design and visible blood on gloves. A wide range of associations were demonstrated between device design and visible blood on gloves or devices and incidence of blood splatter.Conclusions.The results of this evaluation suggest that winged phlebotomy devices with ESIP may produce blood splatter during venipuncture. Reinforcing the importance of eye protection and developing a methodology to assess ocular exposure to blood splatter are major implications for healthcare personnel who use these devices. Future studies should focus on evaluating different designs of intravascular devices (intravenous catheters, other phlebotomy devices) for blood splatter.

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The Mechanical and Structural Properties of Reinforcing Materials used in Prosthetic Herniorrhaphy

Engineering in Medicine ◽

10.1243/emed_jour_1979_008_006_02 ◽

1979 ◽

Vol 8 (1) ◽

pp. 15-19 ◽

Cited By ~ 4

Author(s):

R J Minns ◽

D C Stevens ◽

D M Gore ◽

L F Tinckler

Keyword(s):

Structural Properties ◽

Porcine Skin ◽

Steel Mesh ◽

Mechanical And Structural Properties ◽

Reinforcing Material ◽

Materials Used

Three types of reinforcing material that are used in herniorrhaphy were tested by biaxial straining to obtain their load-extension properties. Steel mesh was by far the stiffest material, followed by porcine skin, then Mersilene mesh, when tested by suturing around their periphery. The Mersilene mesh and porcine skin failed around the holes made by the suture, whilst the sutures failed when used with the steel mesh.

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Encapsulation of the Natural Product Tyrosol in Carbohydrate Nanosystems and Study of Their Binding with ctDNA

Polymers ◽

10.3390/polym13010087 ◽

2020 ◽

Vol 13 (1) ◽

pp. 87

Author(s):

Antonella Rozaria Nefeli Pontillo ◽

Evangelia Konstanteli ◽

Maria M. Bairaktari ◽

Anastasia Detsi

Keyword(s):

Natural Product ◽

Thermal Characteristics ◽

White Wine ◽

Hydrogen Bond Formation ◽

Kneading Method ◽

Calf Thymus ◽

Wide Range ◽

Ft Ir ◽

Molecular Modeling Studies ◽

The Impact

Tyrosol, a natural product present in olive oil and white wine, possesses a wide range of bioactivity. The aim of this study was to optimize the preparation of nanosystems encapsulating tyrosol in carbohydrate matrices and the investigation of their ability to bind with DNA. The first encapsulation matrix of choice was chitosan using the ionic gelation method. The second matrix was β-cyclodextrin (βCD) using the kneading method. Coating of the tyrosol-βCD ICs with chitosan resulted in a third nanosystem with very interesting properties. Optimal preparation parameters of each nanosystem were obtained through two three-factor, three-level Box-Behnken experimental designs and statistical analysis of the results. Thereafter, the nanoparticles were evaluated for their physical and thermal characteristics using several techniques (DLS, NMR, FT-IR, DSC, TGA). The study was completed with the investigation of the impact of the encapsulation on the ability of tyrosol to bind to calf thymus DNA. The results revealed that tyrosol and all the studied systems bind to the minor groove of ctDNA. Tyrosol interacts with ctDNA via hydrogen bond formation, as predicted via molecular modeling studies and corroborated by the experiments. The tyrosol-chitosan nanosystem does not show any binding to ctDNA whereas the βCD inclusion complex shows analogous interaction with that of free tyrosol.

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Assessing the Impact of Government Initiatives on Reducing Poverty amongst Women at Professor Dora Akunyili Women Development Centre in Anambra State, Nigeria

Volume 5 - 2020, Issue 9 - September - International Journal of Innovative Science and Research Technology ◽

10.38124/ijisrt20mar205 ◽

2020 ◽

Vol 5 (3) ◽

pp. 1462-1469

Author(s):

Onugu Charles U ◽

Anumudu Oluchi O ◽

Obianefo Chukwujekwu A

Keyword(s):

Poverty Reduction ◽

Anambra State ◽

Development Centre ◽

Percentage Difference ◽

Before And After ◽

Poverty Status ◽

Household Assets ◽

The Difference ◽

Materials Used ◽

The Impact

The study examined the impact of Government Initiatives of reducing poverty amongst women in Anambra state based on a case study of Professor Dora Akunyili Women Development centre. The paper focused on the activities of the centre in championing poverty reduction among women. A wellstructured questionnaire was used to elicit information from randomly selected 112 trainees for the study. Descriptive statistics such as frequency, percentage and mean were used. Percentage difference was equally used to ascertain the difference in poverty status of women before and after the training. The study showed that the trainees had mean income of N50,405.56 and N151,338.89 before and after the training; mean savings before and after the training was N35,741.11 and N48,150.00; mean expenditure on household food was N21,266.67 and N38,111.11 before and after the training; mean expenditure on household health before and after the training was ₦26,000.00 and ₦28,927.78, while mean expenditure on household assets acquisition before and after the training was ₦27,811.11 and ₦55,075.00 respectively. The major challenges faced by the trainees were administrative bottlenecks and bureaucracy in the release of capital funds, late arrival of materials used for the training, among others.

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Characterization of Polyethylene Carrying Bags Before and After Isothermal Oxidative Aging in an Oven

Revista de Chimie ◽

10.37358/rc.20.3.8029 ◽

2001 ◽

Vol 71 (3) ◽

pp. 534-548

Author(s):

Malik Jehanzeb Khurram ◽

Musa Kaleem Baloch ◽

Leonardo C. Simon ◽

Wajid Rehman ◽

Cun-Yueguo Cun-Yueguo

Keyword(s):

Degradation Process ◽

Point Of View ◽

The Other ◽

Research Report ◽

Sem Images ◽

Oxidative Aging ◽

Before And After ◽

Ft Ir ◽

Index Value ◽

The Impact

Utility of polymeric material is a major contribution to the production of waste, particularly in Pakistan. An easy escape to it is the damping in the land which is not commendable for an environmental point of view. On the other hand, the aging of polymer is analogous to its burial conditions under the soil in the absence of light. Therefore, in this research report, two different brands of polyethylene carrying bags were investigated. One sample was obtained from Pakistan abbreviated as sample `Y` while the other from Canada abbreviated as `E`. In order to accelerate the degradation process and to observe the impact of aging in a shorter span of time, these samples were heated at an elevated temperature (80�C) in an oven for the period of 20 days. The samples were characterized before and after aging with an interval of 2 days by applying different techniques like FT-IR, SEM, DSC, and thermogravimetric analysis (TGA). Carbonyl peak at 1715 cm-1 was observed only in the case of sample `E` displaying carbonyl index value as 28.45 % after 20 days of aging. The SEM images before and after aging revealed that the degradation took place at preferential sites in case of sample `Y` and at numerous sites in case of sample `E`. The results of percent crystallinity obtained by DSC showed an increasing pattern with aging for both the samples and was high in case of sample `E.` The activation energy determined by using Flynn-Wall-Ozawa showed a decreasing pattern for both the samples with aging. It concluded that the thermal aging initiates the process of degradation which was then accelerated by heating in TGA oven. The order of reaction was slightly decreased after aging for both the samples and was found to be independent of the heating rate.

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Accelerated ageing of paper: effect of lignin content and humidity on tensile properties

Heritage Science ◽

10.1186/s40494-021-00611-3 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Edyta Małachowska ◽

Marcin Dubowik ◽

Piotr Boruszewski ◽

Piotr Przybysz

Keyword(s):

Tensile Properties ◽

Ph Value ◽

Lignin Content ◽

Accelerated Aging ◽

Strength Properties ◽

Accelerated Ageing ◽

Hydrothermal Aging ◽

Paper Properties ◽

Factors Affecting ◽

Before And After

AbstractPaper degradation menaces the useful lifetime of books, manuscripts, and works on paper during storage, circulation, and display in libraries, archives, and museums. Severe damages such as embrittlement, decay, and mold often occur to the paper that might threaten to lose cultural heritage. However, the shelf life of papers stored in suitable conditions can be extended by hundreds of years. The most important external factors affecting the deterioration of paper-based materials include, in particular, changes in temperature and air humidity. In this study, the effects of accelerated aging under different conditions, including substantially different relative humidity, were considered relative to the strength properties of the paper sheets. These include the mechanical strength, such as breaking length, tear resistance, and bursting strength of the paper samples before and after dry heat aging and hydrothermal aging. Samples with various content of lignin produced in neutral pH were examined to exclude the adverse influence of acidity on paper properties. The results indicate that impact of moisture on tensile properties and pH-value of paper is much greater than the effect of increased temperature. The results of this work are intended to consolidate and expand the theoretical foundation and provide technical support for the conservators and library staff on the storage of paper cultural relics.

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