Rheology of poly(vinyl chloride) blends

PVC/EVA blends were studied with an extrusion plastometer in order to examine the effect of EVA on the processability of PVC. The melt flow of PVC/EVA blends containing from 4 to 30 weight percent EVA follows a simple power law between 160 and 180°C. EVA reduced the melt viscosity and enhanced processability. Blends of PVC and EVA were morphologically incompatible. The molecular weight of extruded PVC in the blends was unchanged.     

Viscosity of copolymers containing carbon black

The flow behavior of random copolymers of styrene and butyl methacrylate containing specific carbon blacks varying in surface area were studied at various temperatures and shear rates. Master curves of reduced viscosity as a function of shear rate were prepared for the pure copolymers at 150°C. The superposition required vertical and horizontal shifts, proportional to (a_T)^?1 and (a_T)^.53, respectively, where a_T is the shift factor. With the incorporation of carbon black, the viscous response is non-Newtonian exhibiting a yield stress at increasing filler concentration and surface area. Master curves of viscosity against shear rate were generated at fixed filler loadings and surface areas by using a single horizontal shift factor.     

A Discrepancy in Analyses of the MSCEIT--Resolving the Mystery and Understanding Its Implications: A Reply to Gignac (2005).

Replies to comments made by G. E. Gignac (see record 2005-06671-010) on the current authors' original article (see record 2003-02341-015). Gignac reanalyzed the factor structure of the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) and found results that differed from those the authors obtained initially. The authors tracked down the surprising sources of those discrepancies. G. E. Gignac's hierarchical model of emotional intelligence appears promising, and the authors anticipate that further investigations of the MSCEIT factor structure may yield additional information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constraining accommodative homunculi in evolutionary explorations of jealousy: A reply to Barrett et al. (2006).

This article responds to a critique by H. C. Barrett, D. A. Frederick, M. G. Haselton, and R. Kurzban (see record 2006-10940-009), wherein it is argued that manipulations of cognitive constraints cannot be used to test general evolutionary hypotheses regarding the architecture of mind. In making this argument, Barrett et al. focus on what they believe to be faulty logic in D. DeSteno, M. Y. Bartlett, J. Braverman, and P. Salovey's (see record 2002-18731-006) use of such techniques to examine proposed sex differences in jealousy. In presenting their argument, however, Barrett et al. appear to disregard central findings presented in DeSteno et al. (2002) and, in so doing, fail to grasp the interrelations among findings that might readily address their concerns. Here, the authors present arguments for why and when manipulations of cognitive resources may prove useful in investigating evolved psychological mechanisms and, in so doing, situate their use within the ongoing debate concerning evolved sex differences in jealousy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in jealousy: Evolutionary mechanism or artifact of measurement?

Two studies are presented that challenge the evidentiary basis for the existence of evolved sex differences in jealousy. In opposition to the evolutionary view, Study 1 demonstrated that a sex difference in jealousy resulting from sexual versus emotional infidelity is observed only when judgments are recorded using a forced-choice response format. On all other measures, no sex differences were found, both men and women reported greater jealousy in response to sexual infidelity. A second study revealed that the sex difference on the forced-choice measure disappeared under conditions of cognitive constraint. These findings suggest that the sex difference used to support the evolutionary view of jealousy likely represents a measurement artifact resulting from a format-induced effortful decision strategy and not an automatic, sex-specific response shaped by evolution. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mood-induced self-focused attention.

The influence of mood on self-focused attention was explored in 2 experiments involving the induction of moods in the laboratory. Exp 1 tested the hypothesis that mood states, whether pleasant or unpleasant, induce self-focused attention. This hypothesis was supported using a sentence completion task as the measure of self focus. Exp 2 replicated Exp 1 results using a measure of self-complexity as an index of self-focus. These experiments provide support for a model of affect–action sequences the first step of which entails the turning of attention toward the self in response to the arousal of affect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Model filled polymers. XV: The effects of chemical interactions and matrix molecular weight on rheology

In order to explore the effects of chemical composition on the rheological behavior o filled polymeric systems, we prepared polystyrene (9PS) and poly(methyl methacrylate) (PMMA) particles crosslinked with either ethylene glycol dimethacrylate (EGDMA) or divinyl benzene (DVB), and mixed these particles in a PMMA matrix. PS particles crosslinked with 10% EGDMA are better dispersed in a PMMA matrix, compared to PS particles, crosslinked with 10% DVB, due to the compatibilizing effect of EGDMA. For PMMA particles crosslinked with DVB, particle-matrix interactions in a PMMA matrix are smaller than in EGDMA-PMMA filled PMMA. Therefore, particles tend to agglomerate in PMMA composites filled with DVB-PMMA particles, especially in a low molecular weight matrix. We compared PMMA matrices of molecular weights 35,000 and 75,000. Higher particle-matrix interaction in the higher molecular weight matrix resulted in lower relative viscosities for DVB-PS filled systems, due to better dispersion of the particles. Composites filled with EGDMA-PS particles behave similarly to those filled with DVB-PS particles. PMMA composites filled with DVB-PMMA particles have a lower relative viscosity in the higher molecular weight PMMA matrix at low shear rates, due to better dispersion in the higher molecular weight matrix. However at high shear rates, particles are well dispersed in both PMMA matrices and, then, the relative viscosity is higher due to better bonding in the higher molecular weight matrix.     

Shaping perceptions to motivate healthy behavior: The role of message framing.

Health-relevant communications can be framed in terms of the benefits (gains) or costs (losses) associated with a particular behavior, and the framing of such persuasive messages influences health decision making. Although to ask people to consider a health issue in terms of associated costs is considered an effective way to motivate behavior, empirical findings are inconsistent. In evaluating the effectiveness of framed health messages, investigators must appreciate the context in which health-related decisions are made. The influence of framed information on decision making is contingent on people, first, internalizing the advocated frame and, then, on the degree to which performing a health behavior is perceived as risky. The relative effectiveness of gain-framed or loss-framed appeals depends, in part, on whether a behavior serves as an illness-detecting or a health-affirming function. Finally the authors discuss the cognitive and affective processes that may mediate the influence of framed information on judgment and behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Seeking urgent pediatric treatment: Factors contributing to frequency, delay, and appropriateness.

Explored the factors that contributed to mothers' decisions to seek urgent medical attention for their children when symptoms were not of a traumatic nature. 89 mothers (mean age 28.4 yrs) seeking treatment for their children (mean age 5.3 yrs) at a prepaid clinic completed a questionnaire eliciting their expectations regarding the course of their children's problems, seriousness of the problems, perceived responsibility for the symptoms, and extent to which a variety of factors contributed to their decisions to seek treatment. Demographic data and information about each child's symptoms and medical history were also obtained. Four major reasons for seeking treatment were identified: family history of the presenting complaint, worry regarding the symptoms, situational variables, and the extent of the child's illness behavior. The appropriateness of the visit, delay in seeking treatment, and frequency of mothers' use of the pediatric clinic were predicted by the nature of the presenting symptoms (particularly the presence of fever), the ages of the mother and child, and 2 of the reasons for seeking treatment factors (i.e., family history, child's illness behavior). It is suggested that mothers should pay more attention to presenting symptoms and to the children's behavior than to psychosocial stressors in deciding to seek urgent care. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of mood on health-relevant cognitions.

Three experiments assessed the effects of mood on symptom appraisal, health behavior self-efficacy, outcome expectations, and perceptions of vulnerability. Ss in Experiments 1 and 2 were acutely ill, whereas Ss in Experiment 3 were healthy. In each experiment, happy, sad, and neutral moods were induced. In Experiment 1, Ss who experienced sadness reported more aches and pains and greater discomfort than happy Ss. Sad Ss were less confident that they could carry out illness-alleviating behaviors. Experiments 2 and 3 demonstrated that mood's influence of vulnerability perceptions is moderated by health status. Although mood had little impact on perceptions of vulnerability among ill Ss, probability estimates of future negative health-relevant events among healthy Ss were mood sensitive. Seeing oneself as invulnerable to future negative events was accentuated among happy Ss and attenuated among sad Ss. Mood may be an important determinant of care seeking, adherence, and recovery from illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)