The effect of tension during drying on the structure and mechanics of poly(p-phenylene benzobisthiazole) fibers

The effect of tension during drying on the structure and mechanics of poly(p-phenylene benzobisthiazole) (PBT) fibers has been investigated. The application of tension during drying on PBT fibers spun from anisotropic solutions of PBT/Polyphosphoric acid (PPA) results in an enhancement of tensile modulus and yield strength with a reduction in strain to break. The alterations in the tensile properties can be attributed to the straightening of the wet fibrillar network and the reduction in the axial compressive stresses which develop during drying. Modifications in the mechanical behavior of PBT fibers through tension drying can be achieved regardless of the initial spin draw ratio of the fiber. Additionally, tension drying provides a means to maximize the potential stiffness of PBT fibers which have a low spin draw ratio. Lastly, these investigations show that in the processing of PBT fibers, preventing the onset of buckling and aligning the wet fibrillar network with tension during drying is more effective in enhancing the tensile properties than straightening the dried buckled fibers.     

Changing patterns of inpatient care for children and adolescents at the Menninger Clinic, 1988–1994.

The authors describe trends in inpatient psychiatric length of stay (LOS) and admissions for the population of children and adolescents (N?=?784) at the Menninger Clinic from 1988 to 1994. During this period, median LOS declined dramatically from 7 months to 3 weeks, whereas admissions increased 4-fold. The diagnostic case mix changed substantially, with a crossover in modal principal diagnosis from personality disorder to affective disorder. Use of medications became almost universal. Diagnosis and medication use became less important determinants of LOS over time. The practical implications of these patterns include higher patient turnover, fewer inpatient clinical contact hours, and heightened importance of continuity with outpatient care. Research should center on the impact of declining LOS on clinical and functional outcomes for children and adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Wives' employment and husbands' attitudes toward work and life.

Previous research has established that wives' employment has a positive association with the mental health of wives but a negative association with the mental health of husbands. The present study investigated the connections between wives' employment and husbands' work life, using data from the 1977 Quality of Employment Survey on 208 couples in which both husband and wife worked and 408 couples in which only the husband worked. Data indicate that wives' employment had nonspurious negative associations with husbands' job and life satisfaction. Husbands of working wives felt less adequate as family breadwinners than did husbands of housewives, and this appeared to account for their lower levels of job and life satisfaction. Findings suggest that the occupational domain is particularly important to understanding the negative relations between wives' employment and husbands' job and life satisfaction. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Property modifications in poly(p-phenylene benzobisthiazole) fibers with high-tension and high-temperature drying versus postprocessing heat treatment

Modifications in the structure and mechanics of poly(p-phenylene benzobisthiazole) (PBT) fibers have been attempted through high-tension and hightemperature drying and subsequent postprocessing heat treatment experiments. High-tension drying results in an enhancement in tensile properties by offsetting compressive shrinkage stresses during the drying process and improving the molecular alignment within the fiber. Elevated temperature drying under tension further improves the extent and perfection of the lateral molecular order. The increased molecular ordering and improved tensile properties are believed to result from the removal of water and residual acid at elevated temperatures. The final fiber properties after subsequent postprocessing heat treatment are independent of the drying conditions. These results suggest that the ultimate fiber properties are a function of the total strain imposed in all the processing operations (dry jet stretch region, coagulation and drying process, postprocessing heat treatment). The attainment of the fiber's theoretical highmodulus/high-strength properties appears limited by defects such as voids and internal stresses which, in turn, restrict the amount of strain imposed during the fiber process.     

Modification and compatibilization of nylon 6 with functionalized styrenic block copolymers

Much work in recent years had focused on the improvements of the impact properties of engineering thermoplastics by the addition of a low modulus modifier that contains polar moieties as a result of polymerization or that has been modified to contain polar moieties as a result of various grafting techniques. Styrenic block copolymers (styrene-ethylene/butylene-styrene) functionalized with maleic anhydride have proved useful as impact modifiers and compatibilizers in blends with engineering thermoplastics. This paper focuses on the use of these functionalized elastomers to modify nylon 6. In such compositions, a nylon material with unique mechanical performance may be achieved using the functionalized elastomer either alone or in combination with an unfunctionalized styrenic block copolymer. The optimization of performance in these rubber toughened polyamide blends using various types of styrenic block copolymers is discussed. The morphology as it pertains to performance is also reviewed. The information contained herein may prove useful in obtaining a better understanding of the mechanisms of compatibilization and modification of nylon 6 systems.     

Judging mental disorder in youths: Effects of client, clinician, and contextual differences.

Using a vignette-based, mailed survey of 1,401 experienced psychologists, psychiatrists, and social workers, the authors examined how clients' race/ethnicity and clinicians' professional and social characteristics affect their judgment of mental disorder among antisocially behaving youths. Vignettes described problematic behaviors meeting the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) criteria for conduct disorder but contained contextual information suggesting either disorder or nondisorder, following DSM-IV guidelines. Clinicians depended on contextual information to decide whether a mental disorder existed, and they judged White youths to have a disorder more frequently than Black or Hispanic youths. Clinicians' occupation, theoretical orientation, and age also were associated with disorder judgments, whereas their gender, race, and experience were not. Research and training implications of these variations in clinical judgments are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Force–temperature behavior of rigid rod polymeric fibers

The force versus temperature behavior (at constant length) of poly(p-phenylene benzobisthiazole) fibers (PBT) and Kevlar fibers has been investigated. Thermal expansion coefficients are evaluated for heat treated PBT (PBT-HT) and Kevlar 49, to be ?1.1 × 10^?6/°C and ?3.2 × 10^?6/°C, respectively. Kevlar 49, PBT-HT, and steel fibers exhibit a linear thermal elastic behavior whereas Kevlar 29 and as-spun PBT do not. Material changes which occur during heat treatment processing are detected in the force-temperature profile. A correspondence between the thermal and mechanical energy input which induces these material changes has been found.