bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extrusion of humidity‐resistant starch foam sheets
Authors: Yang Zhiguan , Graiver Daniel , Narayan Ramani 
Published: September 2012

AbstractAn annular die is used to extrude cylindrical starch foams which are then sliced to yield foam sheets suitable for cushioning protection and insulation of shipping containers. Although starch foams, as a possible replacement of petroleum‐based foams, have been prepared in the past, their sensitivity to humidity remained a problem. Extensive research in the last few years has been focused on resolving the collapse of the foam at high humidity, improve the cushioning protection, and develop an economical foaming process. However, these issues are still problematic and need to be resolved before such biobased foams can gain entry into the marketplace. In this study, a Box–Behnken statistical design of experiment was used to optimize the properties of foams extruded with various additives. It was found that the density, cell structure, and the rate of water penetration of these foams were affected by the feed rates (e.g., foam composition) of the water, talc, and poly(hydroxy ether) (PHE). The use of PHE was found to be extremely effective to minimize the water sensitivity and it significantly increased the water penetration time of the foam sheets. These starch foams efficiently absorb impacts and recover its physical shape quickly to provide multiple cushion protection for moderately delicate products. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Morphological aspects of injected polypropylene/clay nanocomposite materials
Authors: Salah Hend Ben Hadj , Daly Hachmi Ben , Denault Johanne , Perrin Florence 
Published: September 2012

AbstractPolypropylene (PP) clay nanocomposites were injection‐molded using two different coupling agents based on maleic anhydride‐grafted PP (MA‐g‐PP) and two clay loadings. The morphological aspects of these materials were studied by depth profiling. Molecular chain and clay orientations were characterized using attenuated total reflectance‐infrared analysis and transmission electron microscopy (TEM). Both clay platelets and PP molecular chain orientations were found to decrease from the surface toward the core of the injection–molded specimens. Clay intercalation, characterized by both complementary X‐ray diffraction and TEM, was found to be significantly influenced by both the characteristics of the coupling agent used and the type of residual stresses generated at each layer across the thickness of the injection‐molded parts. The use of low‐molecular weight (Mw) MA‐g‐PP led to a uniform intercalation but with no further exfoliation. The use of higher molecular weight MA‐g‐PP led to a heterogeneous intercalation with some signs of exfoliation. The crystallization behavior of PP clay nanocomposites studied by differential scanning calorimetry showed an increase in the level of crystallinity from the surface to the core of the specimens; these results were also confirmed by scanning electron microscopy. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Preparation and characterization of poly(trimethylene terephthalate)‐poly(ethylene oxide terephthalate) segmented copolymer/multiwalled carbon nanotubes composites by in situ polymerization
Authors: Chen Zhenming , Liu Yan , Yao Chenguang , Yang Guisheng 
Published: September 2012

AbstractPoly(trimethylene terephthalate)‐poly(ethylene oxide terephthalate) block copolymer (PTG)/multiwalled carbon nanotubes (MWCNTs) composites were prepared via in situ polymerization. To improve the dispersion of MWCNTs in the PTG matrix, the poly(ethylene glycol)‐grafted multiwalled carbon nanotubes (MWCNT‐PEG) were produced by the “graft to” method. The transmission electron microscopy observation demonstrated that a homogeneous dispersion of MWCNT‐PEG was obtained. As a consequence, the percolation threshold for the rheology was around 0.5 wt% and the conductivity was ∼1 wt%, respectively. Differential scanning calorimetry and polarized optical microscopy results confirmed that MWCNT‐PEG can act as an effective heterogeneous nucleating agent. Interestingly, the effects of MWCNT‐PEG on crystallization and melting of the poly(ethylene oxide terephthalate) blocks were more pronounced than on those of the PTT blocks. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Physical extruder foaming of poly(lactic acid)—processing and foam properties
Authors: Larsen Åge , Neldin Christoffer 
Published: September 2012

AbstractThe article describes extrusion foaming of poly(lactic acid) (PLA) using carbon dioxide in the supercritical state as foaming agent emphasizing the steps required to establish a stable extrusion process. Low melt strength of PLA plays a role in optimizing processing conditions. The tests included PLA grades of different viscosity in addition to a chain extender. Processing at low temperature is possible due to the plasticizing effect of the CO2 on the PLA melt and a sufficiently low melt temperature is also a prerequisite in production of stable foams due to improved melt strength. Foams were characterized by density, cell structure, crystallinity, and mechanical properties in compression. Low density, microcellular foams with density down to 20–30 kg/m3 were obtained for three different PLA grades. Varying die temperature and pressure drop rate we can explain observed abrupt drops in density with increasing CO2 content by the interplay between cell nucleation and gas diffusivity at given temperatures. An effect on melt strength similar to using a chain extender is achieved by lowering the melt temperature at the die. Observed variations in sample crystallinity do not correlate with foam density. The PLA foams have good energy absorption capability. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Continuous polymerization of methyl methacrylate in a taylor‐couette reactor. II. influence of fluid dynamics on polymer properties
Authors: Liu Zhen , Kind Matthias 
Published: September 2012

AbstractIn this work, the free radical continuous polymerization of methyl methacrylate (MMA) with the solvent xylene and 2,2‐Azoisobutyronitrile (AIBN) as initiator was studied in a laboratory Taylor‐Couette reactor. It was found that the property of the polymerized product (molecular weight distribution) is affected by the fluid dynamic conditions (mean residence time, rotational speed, diameter of the inner cylinder, and gap width). The weight average molecular weight decreases with an increase of the mean residence time, is strongly dependent on the geometry of the reactor, and was found to be independent on the shear rate in the gap. The width of the molecular weight distribution decreases weakly with increasing residence time, increases with increasing shear rate, and weakly depends on the diameter of the inner cylinder. A correlation was developed to describe the weight‐average molecular weight as a function of the Taylor number and the Damköhler number. This correlation is dimensionless and may be used for scaling‐up purposes. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Effects of thermal treatment on the microstructure and thermal and mechanical properties of poly(lactic acid) fibers
Authors: Gao Chengcheng , Ma Hongxin , Liu Xingxun , Yu Long , Chen Ling , Liu Hongsheng , Li Xiaoxi , Simon George P. 
Published: September 2012

AbstractThe microstructure and thermal and mechanical properties of poly(lactic acid) (PLA) fibers after thermal treatment under both taut and free conditions at different temperatures were studied by differential scanning calorimetry, wide‐angle X‐ray diffraction, microscopy with polarized light, an acoustic method and tensile testing. In particular, the effects of thermal treatment conditions on crystallinity, molecular orientation, and mechanical properties, as well as their interrelationships, were investigated. Both the crystal orientation and crystallinity of the PLA fibers were higher after thermal treatment under taut conditions, even though the molecular orientation was not higher. Thermal treatment relaxed orientated segments, which resulted in increasing crystallinity; however, it did not indicate that the overall molecular alignment of the chains (molecular orientation) would necessarily be high. Tensile strength and elongation were increased with increasing treatment temperature up to 150°C, which corresponded to crystallinity and chain relaxation. The crystallinity detected by XRD, enthalpy measured by DSC, birefringence, and molecular orientation were compared to distinguish the effects of crystallinity, orientation of polymer chains, and crystals. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Investigation on variable shear modulus of magnetorheological elastomer based on natural rubber due to change of fabrication design
Authors: Yoon Ji‐Hyun , Yang In‐Hyung , Jeong Un‐Chang , Chung Kyung‐Ho , Lee Jung‐Youn , Oh Jae‐Eung 
Published: September 2012

AbstractA magnetorheological elastomer (MRE) is a smart material that has a reversible and variable modulus in a magnetic field. Natural rubber (NR), which has better mechanical properties than other rubbers, was used as the matrix. Carbonyl iron powder (CIP) was selected for the generation of a magnetic field‐dependent modulus in the MREs. The MRE specimens were cured in an anisotropic mold, which was used to induce a magnetic field. SEM images validated the CIP orientation. The shear modulus of the MREs was evaluated under a magnetic field induced by a magnetic flux generator (MFG). An evaluation system was designed that includes an MFG, which is a device that generates a magnetic field via a continuously variable‐induced current to determine the magnetic field‐dependent shear modulus. The variations of the shear modulus were observed with increasing CIP volume fraction and induced current. The experimental results revealed that the maximum variation rate of the shear modulus was 76.3% for 40 vol% of CIP and an induced current of 4 A. Using these results, the appropriate CIP volume fraction and induced current can be proposed as the guidelines in fabrication design of MREs based on NR. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Investigation of the influence of processing conditions on the thermal, rheological and mechanical behavior of polypropylene nanocomposites
Authors: Mattausch H. , Laske S. , Đuretek I. , Kreith J. , Maier G. , Holzer C. 
Published: September 2012

AbstractThe use of polypropylene (PP)‐layered silicate nanocomposite has attracted great interest in the polymer industry over the last years. On one hand, PP is widely used in many fields of applications because of good performance and cost. On the other hand, the major advantage of layered silicate nanofiller in the polymer matrix is the small amount of filler (<5 wt%) needed to enhance various properties such as Young's modulus. The most commonly used layered silicates are organomodified montmorillonite (MMT). In this study, a PP/organoclay nanocomposite, filled with layered silicate Nanofil SE3010 (1 and 5 wt%), provided by Rockwood Additives, USA, was used. The polymer nanocomposites were prepared via melt intercalation in a laboratory kneader. The compatibilizer (PP grafted with maleic acid anhydride) admixture content relative to the organoclay content (1 and 5 wt%) was chosen at a ratio of 1:1 (clay:compatibilizer). The influence of different processing conditions (rotation speed and residence time) on the thermal, rheological, and mechanical properties and the interlayer distance was investigated. It was the target to determine whether a short and intensive or a long and soft process performs better. Different properties prefer different states of dispersion of MMT in the polymer matrix. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Effect of syndiotactic polystyrene on the crystallization behavior of isotactic polypropylene/syndiotactic polystyrene blends with and without β‐nucleating agent
Authors: Zhang Ronghua , Li Robert Kwok Yiu 
Published: September 2012

AbstractBlends of isotactic polypropylene (PP) and syndiotactic polystyrene (sPS) with and without β‐nucleating agent were prepared using a twin‐screw extruder at 290 °C. Blends of PP/sPS with β‐nucleating agent mainly show β crystalline form, irrespective of high (20 °C min−1) or low (2 °C min−1) previous cooling rates. This suggests that the cooling rates have little effect on the polymorphic composition of PP in PP/sPS blends. The effect of sPS on the crystallization of PP is compared with that of polyamide 6 (PA6). The increase in crystallization temperature of PP is smaller in the presence of sPS than in the presence of PA6; the fold surface free energy of PP/sPS is larger than that of PP/PA6 blends. These results reveal that compared with PA6, sPS has much weaker α‐nucleation effect on the crystallization of PP. The weak α‐nucleation effect of sPS is attributed to the high lattice mismatch between PP and sPS crystals.
Controlling J‐aggregate formation for increased short‐circuit current and power conversion efficiency with a squaraine donor
Authors: Spencer Susan , Hu Harry , Li Qimeng , Ahn Hyo‐Yang , Qaddoura Maher , Yao Sheng , Ioannidis Andronique , Belfield Kevin , Collison Christopher J. 
Published: September 2012

ABSTRACTA squaraine dye is tested for novel application in a near‐infrared‐active organic photovoltaic cell that is subsequently optimized to obtain a power conversion efficiency of 2.4 ± 0.3%. The optimization utilizes an Alq3 buffer layer and macroscopic structure control through the addition of co‐solvents in the spin‐casting process. Co‐solvent addition increases the amount of aggregates present as measured through linear absorption spectroscopy, and there is a concurrent increase in both efficiency and short‐circuit current. An interpretation of the greatly increased current density is presented that describes how increased J‐aggregation likely increases hole mobility and, as a result, charge separation of the photogenerated excited state. Copyright © 2012 John Wiley & Sons, Ltd.
Borderline personality disorder in suicidal adolescents
Authors: Yen Shirley , Gagnon Kerry , Spirito Anthony 
Published: September 2012

ABSTRACTThe diagnosis of borderline personality disorder (BPD) in adolescents has been controversial. Thus, few studies have examined BPD in suicidal adolescents, even though it is strongly associated with suicidal behaviours in adults. This study examines differences between suicidal adolescents with (n = 47) and without (n = 72) BPD on history and characteristics of suicidal behaviour, Axis I co‐morbidity, affect regulation and aggression. Assessments were completed with both adolescents and parents, and consensus ratings based on best available data were analysed. BPD participants were more likely to have a history of suicide attempts and to have been admitted because of a suicide attempt (vs. suicidal ideation). There were no significant differences in self‐injurious behaviours or degree of suicidal ideation. BPD participants also had more psychiatric co‐morbidity and higher aggression scores but no significant differences in affective dysregulation compared with suicidal adolescents without BPD. Diagnostic stability over 6 months was modest. Our results demonstrate that, compared with other acutely suicidal adolescents, the clinical profile of BPD participants is unique and suggests an increased risk for suicidal behaviours. This extends upon other studies that support the construct validity of BPD during adolescence and suggests that BPD should be considered in suicide risk assessment for adolescents. Copyright © 2012 John Wiley & Sons, Ltd.
Vinyl‐terminated liquid‐crystalline dendrimers based on dendritic polyols and their siloxane‐based elastomers
Authors: Lin Yuteng , Sun Jianzhong 
Published: September 2012

AbstractA new series of side‐chain liquid‐crystalline dendrimers (LCDs) by grafting vinyl‐terminated phenyl benzoate‐based promesogens to a novel polypropyleneimine‐derived dendritic polyols are reported. Polarized optical microscopy and X‐ray diffraction studies show that both the compounds display a smectic‐A (SmA) mesophase. The second‐generation dendrimer bearing eight‐branched promesogens exhibits a more stable SmA mesophase with a wide mesomorphic temperature range. It is demonstrated that “promoting groups” in the structure of LCD for the enhancement of mesomorphic stability are unnecessary in the case of strong anisotropic interactions. In contrast to conventional LCDs, these two compounds possess reactive vinyl terminals that endow them with the potential for the preparation of polymeric materials. For the first time, a type of thermoset elastomers is explored from LCDs via hydrosilylation crosslinking reaction of vinyl terminals and siloxane crosslinker. Two‐dimensional X‐ray diffraction study indicates that the lamellar structures of original dendrimers are reserved in the elastomer networks. Stress–strain curves reveal that these elastomers exhibit excellent elasticity under successive uniaxial compression. The combination of anisotropic structures of rigid units and elasticity of flexible networks in this novel series of elastomers makes them promising candidates for the application in artificial muscles or cartilages. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Tunable fluorescence conjugated copolymers consisting of tetraphenylethylene and fluorene units: From aggregation‐induced emission enhancement to dual‐channel fluorescence response
Authors: Shi Jianbing , Wu Yanmei , Sun Shu , Tong Bin , Zhi Junge , Dong Yuping 
Published: September 2012

AbstractA series of new conjugated polymers PTPExFy, which consist of tetraphenylethylene (TPE) units and fluorene (F) units, have been designed and synthesized by Suzuki cross‐coupling polymerization. The polymers PTPExFy exhibited aggregation‐induced emission enhancement and dual‐channel fluorescence response (DCFR) when they were aggregated in solution, and these properties are related with their TPE‐to‐F ratio in the polymer backbone. For PTPE and PTPE0.5F0.5, the fluorescence emission was enhanced by aggregation when water was added into their THF solutions. For the copolymers PTPE0.3F0.7, PTPE0.2F0.8, and PTPE0.1F0.9, the DCFRs were observed when they were aggregated by adding water into their solution, which can be attributed to the different responses of fluorene segments and TPE segments to aggregation. The fluorene segments have an aggregation‐caused quenching characteristic, whereas the TPE segments have an aggregation‐induced emission characteristic. According to the fluorescence lifetime and quantum yield data of the polymer solutions, we have discovered that the polymer's natural life time increases as its TPE content increases. In the solid film, PTPE0.3F0.7 and PTPE0.2F0.8 showed better quantum yield than other polymers, due to the combination of the excellent fluorescent property of the fluorene groups and the nonplanar conformation of the TPE groups. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
High‐efficiency polymer solar cells based on phenylenevinylene copolymer with BF2‐azopyrrole complex and CN‐PC70BM with solvent additive
Authors: Singh Surya Prakash , Pavan Kumar CH , Sharma G. D. , Mikroyannidis J. A. , Singh Manjeet , Kurchania Rajnish 
Published: September 2012

AbstractPower conversion efficiency (PCE) of phenylenevinylene‐based copolymer with BF2 azopyrrole complex (PB)/modified PC70BM, that is, CN‐PC70BM bulk heterojunction solar cells improves from 2.16 to 4.90% using a processing additive and drying condition. The results demonstrate that a processing additive and drying condition provides an effective means to control both the surface roughness and finer interpenetrating networks to enhance the exciton dissociation into free charge carriers, charge transportation, and collection. Taking into the account of simple device fabrication process without thermal annealing, the PCE of the polymer solar cell can further improved by chloronapthalene (CN) additive under the fast drying condition. The average carrier lifetimes extracted from the impedance spectra and found to correlate with measured PCEs. At short circuit conditions and illumination, the average charge carrier lifetime was found vary from 16.8 to 32 μs with power conversion efficiencies ranging from 3.0 to 4.9%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Conjugated polymer‐functionalized graphite oxide sheets thin films for enhanced photovoltaic properties of polymer solar cells
Authors: Lee Rong‐Ho , Huang Jian‐Lun , Chi Chun‐Han 
Published: September 2012

AbstractIn this study, the maleimide‐thiophene copolymer‐functionalized graphite oxide sheets (PTM21‐GOS) and carbon nanotubes (PTM21‐CNT) were developed for polymer solar cell (PSC) applications. The grafting of PTM21‐OH onto the CNT and GO sheets was confirmed using FTIR spectroscopy. PTM21‐CNT and PTM21‐GOS exhibited excellent dispersal behavior in organic solvents. Better thermal stability was observed for PTM21‐CNT and PTM21‐GOS as compared with that for PTM21‐OH. In addition, the optical band gaps of PTM21‐GOS and PTM21‐CNT were lower than that of PTM21‐OH. We incorporated PTM21‐GOS and PTM21‐CNT individually into poly(3‐hexylthiophene) (P3HT)/[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) blends for use as photoconversion layers of PSCs. Good distributional homogeneity was observed for PTM21‐GOS or PTM21‐CNT in the P3HT/PCBM blend film. The UV–vis absorption peaks of the blend films red‐shifted slightly upon increasing the content of PTM21‐GOS or PTM21‐CNT. The band gap energies and LUMO/HOMO energy levels of the P3HT/PTM21‐GOS and P3HT/PTM21‐CNT blend films were slightly lower than those of the P3HT film. The conjugated polymer‐functionalized PTM21‐GOS and PTM21‐CNT behaved as efficient electron acceptors and as charge‐transport assisters when incorporated into the photoactive layers of the PSCs. PV performance of the PSCs was enhanced after incorporating PTM21‐GOS or PTM21‐CNT in the P3HT/PCBM blend. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Predictors of desire for help in oncology outpatients reporting pain or distress
Authors: Clover Kerrie , Kelly Pete , Rogers Kerry , Britton Ben , Carter Gregory Leigh 
Published: September 2012

AbstractObjectiveAlthough effective treatments for pain and distress are available, many patients do not access them. Improved understanding of patients’ desire for help may improve uptake of services.MethodsData were collected as part of the QUICATOUCH screening program at an Australian regional hospital. Patients over threshold for pain were asked if they would like help with their pain and those over threshold for distress were asked if they would like help with their distress. Multivariate logistic regression analyses were conducted to identify independent predictors of desire for help.ResultsOf 305 patients over threshold for pain; 59% wanted help, increasing from 13% at a pain score of one to 90% at a pain score of 10. Of 274 patients over threshold for distress, 30% wanted help, increasing from 21% at a distress score of four to 41% at a distress score of 10. Pain score was the only significant independent predictor of desire for help with pain, with an odds ratio (OR) of 1.50 (95%CI 1.33‐1.70) for every point increase in pain score. Distress score was the only significant independent predictor of desire for help with distress with an OR of 1.29 (95%CI 1.11‐1.50) for every point increase in distress score.ConclusionsAlthough desire for help with pain and distress increased with respective symptom intensity, many patients indicated they did not want help with these symptoms. Patient reluctance to seek help may constitute a barrier to realising the full potential of screening programs in reducing pain and distress. Copyright © 2012 John Wiley & Sons, Ltd.