Retardation Tests Research Articles

Bayesian hierarchical model with MCMC for optical cable flame retardancy tests

We report a model and method for calculating the probability of an optical fiber cable passing a flame retardancy test (FRT). The method uses a Bayesian approach that accounts for variations in the experimental conditions between tests. We show that adding a hierarchy to the empirical model shrinks the posterior distributions and discuss the applicability of the hierarchical model to various test environments. The model uses the average smoke parameter as the predictor and can be extended to other test responses such as the peak smoke, flame spread, or toxicity.

Impregnation of Preservative and Fire Retardants into Japanese Cedar Lumber by Passive Impregnation

Copper azole type B (CAz-B) preservative and polyphosphatic carbamate (PPC) fire retardants were impregnated in succession into green (97% MC) and kiln-dried (18% MC) Japanese cedar (Cryptomeria japonica (L.f.) D.Don) lumber by the passive impregnation method to prolong the period of lumber use by increasing its resistance to fire and biological degradation. Lumber was dried with a kiln or by air-drying. Total chemical retention, penetration, leaching, decay resistance (JIS K 1571), and fire retardancy (ISO 834-1 standard, 20 minutes) tests were performed according to the mentioned standards. Preservative retention was higher in the green lumber (4.97 kg/m3) compared with the kiln-dried (4.88 kg/m3) lumber. However, fire retardant retention was similar for both lumber types (107 and 111 kg/m3). Leaching was higher in kiln-dried lumber (21.8%) compared to air-dried lumber (14.4%), although there were no significant differences in the decay resistance test between these two lumber types. The fire performance of both lumber types was similar in the fire resistance test. Therefore, the passive impregnation method can be used effectively for impregnation of both preservatives and fire retardants into wood.

D-cycloserine does not facilitate fear extinction by reducing conditioned stimulus processing or promoting conditioned inhibition to contextual cues

The NMDA receptor partial agonist d-cycloserine (DCS) enhances the extinction of learned fear in rats and exposure therapy in humans with anxiety disorders. Despite these benefits, little is known about the mechanisms by which DCS promotes the loss of fear. The present study examined whether DCS augments extinction retention (1) through reductions in conditioned stimulus (CS) processing or (2) by promoting the development of conditioned inhibition to contextual cues. Rats administered DCS prior to extinction showed enhanced long-term extinction retention (Experiments 3 and 4). The same nonreinforced CS procedure used in extinction also reduced freezing at test when presented as pre-exposure before conditioning, demonstrating latent inhibition (Experiment 1). DCS administered shortly prior to pre-exposure had no effect on latent inhibition using parameters which produced weak (Experiment 2) or strong (Experiment 3) expression of latent inhibition. Therefore, DCS facilitated learning involving CS-alone exposures, but only when these exposures occurred after (extinction) and not before (latent inhibition) conditioning. We also used a retardation test procedure to examine whether the extinction context gained inhibitory properties for rats given DCS prior to extinction. With three different footshock intensities, there was no evidence that DCS promoted accrual of associative inhibition to the extinction context (Experiment 4). The present findings demonstrate that DCS does not facilitate extinction by reducing CS processing or causing the extinction context to become a conditioned inhibitor. Investigations into the mechanisms underlying the augmentation of extinction by DCS are valuable for understanding how fear can be inhibited.

Effects of poly(dimethylsiloxane) and inorganic fillers in halogen free flame retardant poly(ethylene-co-vinyl acetate) compound: A chemometric approach

A quaternary system based on poly(ethylene-co-vinyl acetate) has been studied by Mixture Design in order to analyse the effect of additives on flame retardant properties. The FR components of the system are magnesium hydroxide (MDH), a silicon additive (Sil) based on poly(dimethylsiloxane) and a calcium borate additive (CaB). Many parameters from different flame retardant tests (LOI, UL94-V, DIN 4102 B2 and Cone Calorimeter) are selected as experimental responses and mathematical models with good quality are obtained for most of them. Principal Components Analysis (PCA) on flame retardant parameters points out no particular strong correlations among the three FR tests. The Experimental Design (DoE) approach allows minimization of the number of experiments and analysis of the influence of each component and of the interactions among them. Sil additive shows positive effects on LOI results and in the heat release rate and the fillers, mostly MDH, have positive influence on Cone Calorimeter and vertical burning test performance. Two optimal formulations have been obtained with improved stability of the residue together with LOI value in one case and Cone Calorimeter performance in the other case.

CFRP Chip 표면처리에 따른 페놀복합재료의 강화, 내열성 및 난연성 향상

CFRP chip is the byproduct from carbon fiber reinforced plastic (CFRP) processing. CFRP chip is not simply a waste mainly composed of fine carbon fiber and epoxy resin. CFRP chip keeps matrix to maximize their reinforcing effect. To obtain a uniform length of carbon fiber in CFRP chip, chip was chopped ina mortar. CFRP chip should be purified to get better interface adhesion. Epoxy resin on the carbon fiber was removed by H2O2 surface etching treatment. Optimal dispersion and fabrication conditions of CFRP chip embedded in phenolic resin were determined by thermal stability for fire retardant applications. CFRP chip-phenolic composite exhibits better mechanical and thermal properties than neat phenolic resin. Surface condition of CFRP chip-phenolic composite was evaluated by static contact angle measurement. Contact angle of CFRP chip-phenolic composite was greater than neat phenolic due to heterogeneous condition of fine carbon fibers. From the evaluation for fire retardant (ASTM D635-06) test, thermal stability of CFRP chip-phenolic composite was found to be improved with higher concentration of CFRP chip.

Synthesis and characterization of water borne intumescent fire retardant varnish based on phosphate resin acid cold cured amino resin

In this research, a water borne intumescent fire retardant varnish based on phosphate resin acid (PRA) cold cured amino resin was synthesized. Infrared (IR) spectrum proved that PRA was from 1,4-butanediol diglycidyl ether (BDE) and epoxy resin E-51 (E-51) via the reaction between epoxy group and POH of phosphate ester acid of N-butyl alcohol (BA) and pentaerythritol (PT). The introduction of BDE and E-51 improved water resistance and flexibility of painted film. The fire retardancy test demonstrated that a higher phosphorus content is beneficial to the intrinsic fire retardancy of painted films, but the high quality char formation is another key of fire retardancy of painted films. The TG and DTA proved: E-51 and PT are true carbon source that is beneficial to form a high quality charred layer, but their high combustion heat is detrimental to the intrinsic fire retardancy of painted film material. BDE is beneficial to increase the intrinsic fire retardancy of painted film material, but detrimental to form a high quality charred layer. The conclusion also is showed directly by the scanning emission microscopy (SEM). To achieve high performance painted film, all the components need to be balanced perfectly.

Analysis of an Electric Vehicle with a BLDC PM Motor in the Wheel Body

The paper deals with the conception of the test bed for the permanent magnet brushless DC motor (PM BLDC) with parameter verification. The tested motor is destined for installation in the wheel body. The test bed HW and SW equipment is described in the paper. This equipment enables the automated measuring of load-rise, temperature-rise, and retardation tests. The test's aim is to obtain attested specifications for a vehicle dimensioning methodology design based on the knowledge of its dynamic behaviour and the track grading, and eventually of its energy consumption, action radius, etc.

Preparation, properties and application of tamarind seed gum reinforced banana fibre composite materials

Technology has been developed to prepare a biodegradable and environmental friendly composite material from tamarind seed gum and banana fibre. Tamarind seed gum is prepared from the endosperm of roasted seeds of the tamarind tree. The different temperature condition maintained for roasting the seeds are 130, 160, and 180°C. Banana fibres are extracted from different varieties of banana trees, which are used for the preparation of composite material. The tensile strength of the composite material is measured and shows dependency on the variety of banana fibre used in the preparation and also the roasting temperature condition of the tamarind seed. Tamarind seed gum (the seed roasted at the temperature condition of 130°C) and Red banana fibre composite shows the highest tensile strength of 3.97 MPa and Poovan fibre composites shows the lowest tensile strength of 1.90 MPa. The composite material of other varieties shows tensile strength in between these two values. The percentage of moisture absorption of the composite material has a direct correlation to the tensile strength. In addition, investigation on fire retardant test of tamarind seed gum — banana fibre composite material revealed that untreated and varnish coated banana fibre composite material has good fire retardant characteristics. This is an important feature to promote the use of this composite material as a false roofing material instead of thermocole.

Lack of evidence for inhibitory processes in over-selectivity

Stimulus over-selectivity can be defined as control over behavior being exerted by one aspect of the environment at the expense of other equally salient aspects of the environment, and is a common problem for discrimination learning under conditions of cognitive strain, and in intellectual disorders. Non-clinical participants exposed to a concurrent task load were trained and tested on a two-component trial-and-error discrimination task to investigate whether inhibition plays a role in producing under-selectivity by using both summation and retardation tests. Experiment 1 found evidence for the over-selectivity effect, and replicated the finding that revaluation of a previously over-selected stimulus allows emergence of control by a previous under-selected stimulus, despite the latter stimulus receiving no direct conditioning. The under-selected cue was not found to gain any conditioned inhibitory status, as reflected by summation (Experiment 2), and retardation (Experiment 3), tests. The results extend the literature explaining over-selectivity as a post-acquisition failure.

Deactivation and reactivation of the inhibitory power of a conditioned inhibitor: Testing the predictions of an attentional-associative model

An attentional-associative model (Schmajuk, Lam, & Gray Journal of Experimental Psychology: Animal Behavior Processes, 22, 321-349, 1996) assumes that nonreinforced presentations of an inhibitory conditioned stimulus (CS) do not decrease its inhibitory associations. However, the model predicts that extended presentations will decrease attention to the inhibitor, thereby decreasing both (1) the expression of its inhibitory power in a summation test and (2) the rate of acquisition in a retardation test. The model also predicts that subsequent presentations of the inhibitory CS with a novel CS will increase both (1) and (2). Using a predictive learning design in humans, Experiment 1 examined the predictions involving the summation tests, whereas Experiments 2 and 3 examined the predictions involving the retardation tests. Experimental results were in agreement with the predictions of the model.

Extinction context as a conditioned inhibitor

Two lick suppression experiments using rats were conducted to determine whether extinction of a punctate excitor in a particular context would result in that context becoming a conditioned inhibitor, as defined by passing both summation and retardation tests. The role of extinction trial spacing was investigated as a possible determinant of whether the extinction context would become inhibitory. Experiment 1 demonstrated that, although inhibition was evident using either massed or spaced extinction trials, spaced trials reduced measurable inhibition as assessed by the summation test, but trial spacing had no influence on retardation test performance. Experiment 2 confirmed Experiment 1's conclusions while controlling for the influence of latent inhibition on the retardation test. In Experiment 2, the context proved inhibitory only following massed extinction trials. These data suggest that, at least with select parameters, an extinction context can become inhibitory.

Flame retarding PC/ABS resins having superior thermomechanical properties

Triphenyl phosphate (TPP) is well known to be one of the most effective flame retardants for acrylonitrile-butadiene-styrene copolymer (ABS) and its blending resins, such as polycarbonate (PC)/ABS, among various phosphorous-based compounds. However, TPP can also play a role as a plasticizer, which decreases the mechanical properties of PC/ABS resins at high temperature. Furthermore considerable amount of TPP has to be evaporated during molding process due on its much lower evaporation temperature. To overcome these shortcomings, we tried to immobilize TPP by grafting on butadiene moiety of ABS. FT-IR analysis of prepared TPP-grafted ABS (ABS-g-TPP) comparing with TPP, ABS and their blend confirmed that chemical reactions happened between TPP and ABS resins and it was attributed to the graft reaction of TPP onto butadiene moieties. Prepared ABS-g-TPP resins were blended with PC at various compositions to be prepared as testing specimens by injection molding. The physical characteristics such as mechanical properties, thermal stability, and flame retarding properties of the PC/ABS-TPP graft copolymer were analyzed through Vicat softening temperature, IZOD impact strength, transmission electron microscope, and UL94 flame retardation tests. Results showed that PC/ABS-g-TPP resin takes better thermomechanical properties than the existing PC/ABS resins at relatively low additional TPP amounts.

Nicotine trained as a negative feature passes the retardation-of-acquisition and summation tests of a conditioned inhibitor

Nicotine functions as a negative feature in a Pavlovian discriminated goal-tracking task. Whether withholding of responding to the conditional stimulus (CS) reflects nicotine functioning as a conditioned inhibitor is unknown. Accordingly, the present research sought to determine whether nicotine trained as a negative feature passed the retardation-of-acquisition and summation tests, thus characterizing it as a pharmacological (interoceptive) conditioned inhibitor. In the retardation test, rats received either nicotine (0.4 mg/kg) or chlordiazepoxide (5 mg/kg) negative feature training in which the drug state signaled when a 15-sec light CS would not be paired with sucrose; light was paired with sucrose on intermixed saline sessions. Following acquisition of the discrimination, both groups received nicotine CS training in which sucrose was intermittently available on nicotine but not intermixed saline sessions. Acquisition of conditioned responding to the nicotine CS was slower in the nicotine negative feature group than in the chlordiazepoxide negative feature group. In the summation test, rats were assigned to either the nicotine negative feature group or a pseudoconditioning control. In this control, the light CS was paired with sucrose on half the nicotine and half the saline sessions. Both groups also received excitatory training in which a white noise CS was paired with sucrose. The summation test consisted of presenting the white noise in conjunction with nicotine. Conditioned responding evoked by the white noise was decreased in the negative feature but not the pseudoconditioning group. Combined, the results provide the first evidence that an interoceptive stimulus (nicotine) can become a conditioned inhibitor.

Flame retardation of glass-fibre-reinforced polyamide 6 by a novel metal salt of alkylphosphinic acid

Aluminum salts of phosphinic acid mixture of diisobutylphosphinic acid and monoisobutylphosphinic acid (HPA-2TBA-Al) and glass fibres were compounded with polyamide 6 to prepare a series of flame retardant GF/PA6 composites via melt blending. The flame retardance and burning behaviors of the composites were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), and Cone calorimeter test. The thermal properties and decomposition kinetics were investigated by thermogravimetric analysis (TGA) under N 2 atmosphere. Addition of HPA-2TBA-Al results in an increased LOI value, a UL-94 V-0 rating together with a decrease in both the values of PHRR and THR in Cone calorimetric analysis. Visual observations and scanning electronic microscopy (SEM) after flame retardant tests confirmed the char-formation which acts as a fire barrier in condense phase. Analysis of cone calorimeter data indicates that gas phase flame retardant mechanism exists in the GFPA6/HPA-2TBA-Al system.

Controlled release of cell-permeable gene complex from poly(L-lactide) scaffold for enhanced stem cell tissue engineering

The use of tissue engineering to deliver genes to stem cells has been impeded by low transfection efficiency of the inserted gene and poor retention at the target site. Herein, we describe the use of non-viral gene transfer by cell-permeable peptide (CPP) to increase the transfection efficiency. The combination of this technique with the use of a controlled release concept using a poly ( l-lactide) scaffold allowed for prolonged uptake in stem cells. High transfection efficiency was obtained using a human-derived arginine-rich peptide denoted as Hph-1 (YARVRRRGPRR). The formation of complex between pDNA and Hph-1 was monitored using gel retardation tests to measure size and zeta potential. Complex formation was further assessed using a DNase I protection assay. A sustained gene delivery system was developed using a fibrous 3-D scaffold coated with pDNA/Hph-1 complexes. Transfection efficiency and the mean fluorescence intensity of human adipose-derived stem cells (hASCs) on the sustained delivery scaffold were compared to those of cells transfected via bolus delivery. Plasmid DNA completely bound Hph-1 at a negative-to-positive (N/P) charge ratio of 10. After complex formation, Hph-1 appeared to effectively protect pDNA against DNase I attack and exhibited cytotoxicity markedly lower than that of the pDNA/PEI complex. Plasmid DNA/Hph-1 complexes were released from the scaffolds over 14 days and were successfully transfected hASCs seeded on the scaffolds. Flow cytometry revealed that the transfection efficiency in hASCs treated with pDNA/Hph-1 complex was approximately 5-fold higher than that in cells transfected using Lipofectamine. The sustained delivery system showed a significantly higher transfection efficiency and remained able to transfect cells for a longer period of time than bolus delivery. These results suggest that cell-scaffold-based tissue regeneration can be further improved by transduction concept using CPP and controlled release using polymeric scaffold.

Development of an idle speed engine model using in-cylinder pressure data and an idle speed controller for a small capacity port fuel injected SI engine

An idle speed engine model has been proposed and applied for the development of an idle speed controller for a 125 cc two wheeler spark ignition engine. The procedure uses the measured Indicated Mean Effective Pressure (IMEP) at different speeds at a constant fuel rate and throttle position obtained by varying the spark timing. At idling conditions, IMEP corresponds to the friction mean effective pressure. A retardation test was conducted to determine the moment of inertia of the engine. Using these data, a model for simulating the idle speed fluctuations, when there are unknown torque disturbances, was developed. This model was successfully applied to the development of a closed loop idle speed controller based on spark timing. The controller was then implemented on a dSPACE Micro Autobox on the actual engine. The Proportional Derivative Integral (PID) controller parameters obtained from the model were found to match fairly well with the experimental values, indicating the usefulness of the developed idle speed model. Finally, the optimized idle speed control algorithm was embedded in and successfully demonstrated with an in-house built, low cost engine management system (EMS) specifically designed for two-wheeler applications.

Conditioned inhibition in a rodent model of attention-deficit/hyperactivity disorder.

A deficit in inhibition may underlie some of the symptoms of attention-deficit/hyperactivity disorder (ADHD), particularly impulsivity. However, the data on inhibitory deficits in children with ADHD are mixed. Moreover, there has been little characterization of inhibitory processes in animal models of ADHD. Pavlov's conditioned inhibition procedure allows a direct assessment of the inhibitory status of a stimulus via summation and retardation tests. Therefore, in the current study, we examined conditioned inhibition in spontaneously hypertensive rats (SHRs), the most well-validated animal model of ADHD. SHRs and Wistar rats were trained in a simultaneous feature-negative discrimination in eyeblink conditioning. Each session consisted of a mixture of 2 trial types: a tone paired with a periocular stimulation (A+) or a tone and light presented simultaneously without a periocular stimulation (XA-). Both SHRs and Wistars were able to discriminate A+ from XA- trials. In subsequent summation (X presented simultaneously with a different conditioned excitor, B) and retardation (X paired with the periocular stimulation) tests, the presence of inhibition to X was confirmed in both SHRs and Wistars: X reduced responding to B, and X was slow to develop excitation when paired with periocular stimulation. These results are the first to demonstrate Pavlovian conditioned inhibition in SHRs and to use summation and retardation tests to confirm X as a conditioned inhibitor. The data indicate that conditioned inhibition is intact in SHRs; thus, inhibitory processes that do not require prefrontal cortex or cerebellum may be normal in this strain.

Plasma Surface Functionalization of Biaxially Oriented Polypropylene Films with Trimethyl Borate

The radiofrequency plasma (13.56 MHz) was employed to polymerize trimethyl borate (TMB) monomer/N2 gas mixture on the surface of biaxially oriented polypropylene (BOPP) films. Plasma polymer coated polypropylene films were examined by flame retardancy test (limiting oxygen index, LOI). The highest LOI value calculated for the untreated BOPP sample was 18.4 (v/v O2%) and 24.2 (v/v O2%) for the 55 W 30 minutes treated sample. The plasma polymers were characterized by FTIR spectroscopy and AFM. According to the FTIR results, the -OH, B-CH3, B-O, and BH2 functional groups were detected. It was found that the highest surface roughness belonged to 40 W 30 min treated BOPP sample which was calculated as 9.78 nm (10 μm × 10 μm). Moreover, the wettability of the modified BOPP film surfaces was characterized via contact angle measurements. The water contact angle values have decreased from 109.6? to the lowest value of 68.2? after the plasma treatment. The results showed that TMB/N2 plasma modification could be used as an alternative method for the enhancement of flame retardancy and hydrophilicity of BOPP film.

Acoustical and fire-retardant properties of jute composite materials

This research aims to study the acoustical and flammability properties of biodegradable and easily disposable natural fibre jute and its composite for noise reduction in house hold appliances, automotive and architectural applications. Acoustical properties of jute fibre and felt (natural rubber latex jute composite) were measured in terms of normal specific sound absorption coefficient and sound transmission loss whereas fire retardant tests included limiting oxygen, flame propagation and smoke density test. The results illustrate that low density jute is a better sound absorber as compared to high density jute material, moreover natural rubber latex jute composite gives higher sound transmission class value than jute felt/cloth. Results were also compared with commercially available synthetic, non-biodegradable, glass fibre which indicates that the noise reduction coefficient value and sound transmission class rating of natural rubber latex jute felt are comparable to that of the popular fibre glass. Fire retardant tests show composite’s high limiting oxygen index value as compared to fibreboard and other natural sound absorbing material, wool, low smoke density rating and low light absorption with respect to fibre glass as well as self fire extinguishing ability.

Investigation on Flame Retardancy and Antidripping of New Intumescent Flame Retardant Polypropylene Film

A novel intumescent flame retardant (IFR) system consisting of a novel char forming agent (CFA), modified ammonium polyphosphate (MAPP), a synergistic agent (4A zeolite) and an antidripping agent (SN3300) was used in an intumescent flame retardant polypropylene film (IFR-PP film). The original ammonium polyphosphate (OAPP) was modified by octadecylamine to enhance its compatibility with the PP matrix. According to the results obtained from the flame retardancy tests, MAPP had a higher efficiency than OAPP, and the IFR-PP film without the antidripping agent reached a high limiting oxygen index (LOI) value, but it failed to pass UL-94 VTM-0 rating (0.2 mm). The reasonable loading of SN3300 was 0.10~0.15 wt.% (26 wt.% loading of IFR). Greater or smaller loadings did not help the samples to pass VTM-0 rating, and even deteriorated the flame-retardancy of the film. Based on thermogravimetric analytical data, the IFR enhanced the thermal stability of composites at high temperature and effectively increased the char residue. The cone results demonstrated that the IFR could reduce the flammability of PP films based on reduced heat release rate (HRR), total heat release (THR), smoke production rate (SPR) and total smoke production (TSP); also IFR containing MAPP became more effective in reducing smoke release than one containing OAPP The mechanical properties test results showed that films containing MAPP had better tensile strength and tear strength. The morphological structures observed by scanning electron microscopy (SEM) showed that MAPP had much better compatibility with a PP matrix than OAPP, and it made the char layer become more homogeneous and dense.