It is well established that there is an academic achievement gap between students from high and low socioeconomic family backgrounds. However, how being brought up and living in different socioeconomic backgrounds impacts adolescent development, particularly their creative capabilities and creativity-related personality traits, is not well understood. This study compared creative capabilities and traits of 8th grade students of 2 school districts: a suburban, upper-middle class community and an urban community with a large proportion of families under poverty, located in a northeastern state. The results provide compelling evidence for a creativity gap. The study also found a possible mediating role of academic achievement and intrinsic cognitive motivation, suggesting that the psychosocial processes and mechanisms leading to the creativity gap are tractable. Implications of the findings for optimal adolescent development and social interventions are discussed.

The present article evaluates the effect of variation of WF on the tensile strength, modulus, and elongation at break. The pin-bearing properties usually correlate well with tensile properties. Tensile strength and pin-bearing strength decrease but tensile modulus increases on addition of WF. The tensile strength, pin-bearing strength, and mode of pin-bearing failure also depends on the void content. Increase in void content has a detrimental effect on all the mechanical properties. Wide variation is observed in impact strength because of unpredictable void content due to use of non-vented extrusion process. TGA indicates insignificant effect of WF on thermal stability of composites. Infrared spectroscopy indicates some interaction between PVC and WF.

Polypropylene (PP) is one of the fastest growing thermoplastic polymers in the world, second only to polyethylene. This is primarily due to its excellent balance of physical and chemical properties at a lower cost. PP however possesses low melt strength on account of its linear structure and hence is not easily amenable to processing techniques that involve free surface stretching deformations like thermoforming, blow molding and extrusion film casting. One way to enhance the melt strength of PP is to incorporate long chain branches in its molecular architecture. The present study focuses on the impact of rheology of linear and branched PP on their thermoforming characteristics. Two grades each of linear and long chain branched (LCB) PP homopolymer and impact copolymer (ICP) were used. It was observed that the LCB-PP homopolymer and LCB-ICP showed higher flow activation energy, reduced value of loss tangent and nearly equal frequency dependence of storage and loss moduli in shear rheology. Also, a strong strain hardening behavior was displayed in extensional rheology by the LCB grades. Plug assist thermoforming experiments were carried out to assess the effect of long chain branching on surface strain and thickness distribution for axisymmetric cups of two draw ratios. Biaxial surface strain maps of the formed cups were quantified using Grid Strain Analysis (GSA). Thermoformed cups made from LCB-PP homopolymer and LCB-impact copolymer showed lower surface strain and overall higher thickness as compared to cups made from their linear counterparts, which is in accordance with what might be expected from their rheology.

Plug temperature is a key parameter affecting the thickness distribution of thermoplastic components made by plug assist thermoforming. For a specified pair of plug and plastic sheet, the variation in plug temperature can alter the coefficient of friction (COF) between the pair. We show here how the temperature dependence of COF influences the nature and extent of biaxial stretching of the sheet and consequently the thickness distribution of the thermoformed component. In the present study, high impact polystyrene (HIPS) sheets were thermoformed into axisymmetric cups using a plug-assist process in which the aluminum plug temperature (Tplug) was varied from ambient to above the glass transition temperature of HIPS (∼100 °C). Biaxial strain maps on the surfaces of the formed cups were measured and quantified using Grid Strain Analysis (GSA). Thickness distributions of the cups were also measured. Temperature dependent COF between HIPS and aluminum was determined independently using a rotational rheometer. The measured COF was low for T < 100 °C, whereas it increased appreciably at and above 100 °C. We conclude that when Tplug < 100 °C the HIPS sheet slips on the plug during forming, and this results in biaxial stretching of the base and walls of the formed cup. In contrast for Tplug > 100 °C, a significant reduction in the magnitude of slip is expected. Here the sheet is gripped at the clamp and by the plug during forming which causes reduced biaxial stretching of the base and increased uniaxial stretching of the walls of the cup. Simulations of plug-assist thermoforming using a temperature dependent COF showed qualitative agreement with the GSA data thereby supporting our inferences.

Composites with polyvinyl chloride (PVC) as major matrix constituent, ethylene vinyl acetate (EVA) as polymeric plasticizer and wood flour (WF) and fly ash (FA) as filler were extruded. Morphology of the samples was studied using scanning electron microscopy (SEM). Morphological study indicated good dispersion of the constituents. Infrared spectroscopy (IR) indicates interaction between EVA and PVC and also between the polymeric matrix and WF. The effect of various constituents on glass transition temperature (T g ) was evaluated using differential scanning calorimetry. Addition of EVA decreased the T g , whereas T g was increased due to addition of WF and FA. Study indicated that reduction in T g on addition of EVA was compensated by increase in T g due to addition of WF. The contribution of FA to change in T g was not significant.