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Coronavirus disease 2019 (COVID‐19) due to infection with severe acute respiratory syndrome coronavirus 2 causes substantial morbidity. Tocilizumab, an interleukin‐6 receptor antagonist, might improve outcomes by mitigating inflammation. We conducted a retrospective study of patients admitted to the University of Washington Hospital system with COVID‐19 and requiring supplemental oxygen. Outcomes included clinical improvement, defined as a two‐point reduction in severity on a six‐point ordinal scale or discharge, and mortality within 28 days. We used Cox proportional‐hazards models with propensity score inverse probability weighting to compare outcomes in patients who did and did not receive tocilizumab. We evaluated 43 patients who received tocilizumab and 45 who did not. Patients receiving tocilizumab were younger with fewer comorbidities but higher baseline oxygen requirements. Tocilizumab treatment was associated with reduced C‐reactive protein, fibrinogen, and temperature, but there were no meaningful differences in time to clinical improvement (adjusted hazard ratio [aHR], 0.92; 95% confidence interval [CI], 0.38–2.22) or mortality (aHR, 0.57; 95% CI, 0.21–1.52). A numerically higher proportion of tocilizumab‐treated patients had subsequent infections, transaminitis, and cytopenias. Tocilizumab did not improve outcomes in hospitalized patients with COVID‐19. However, this study was not powered to detect small differences, and there remains the possibility for a survival benefit.

Per-2,3-acetyl-β-cyclodextrin is first synthesized by selective modification and used as core molecule for preparing a star-shaped macromolecular antioxidant (β-CD-DBHMP) via a two-step method. β-CD-DBHMP is characterized by 1H-NMR, MALDI-TOF MS, and TGA. The performance of β-CD-DBHMP as antioxidant for natural rubber is determined by OIT and accelerated thermal aging test, and its extraction resistance is also investigated. The results show that β-CD-DBHMP with a Mn of 4.03 × 103 g · mol−1 is successfully obtained, and it possesses high thermal stability with an initial weight loss temperature of 290 °C. Moreover, β-CD-DBHMP is superior to DBHMP for the stabilization of NR against thermal oxidation, and exhibits better extraction resistance. Its possible antioxidative mechanism is also discussed.

A simple and effective way was expected to improve the blending of ultra-high-molecular-weight polyethylene (UHMWPE) in high-density polyethylene (HDPE) matrix. HDPE/UHMWPE blends were subjected to high temperature melting (HTM) at 280°C for up to 10 h, followed by shear at 175°C. These results were examined by scanning electron microscopy, polarized optical microscopy, and melt rheological behavior. UHMWPE particle was swelled partially during HTM, and this swollen region could be peeled from the particle by the subsequent shear, which resulted in more “dissolution” of UHMWPE in HDPE matrix. These results were also validated by the rheological behavior. POLYM. ENG. SCI., 55:270–276, 2015. © 2014 Society of Plastics Engineers

The morphology distribution of a model polymer blend, polystyrene (PS)/polyethylene (PE), molded by multimelt multi-injection molding (MMMIM) process was studied by scanning electronic microscopy and polarizing light microscopy. An unusual double skin/core morphology was observed. The minor phase, PS, showed highly deformed morphology in both the skin layer near the mold wall and the core layer near the skin/core layer's interface. Meanwhile, in the regions that highly deformed PS phase showed, highly ordered cylindritic crystal structures of PE are also formed. As we all know the driving force and the basic prerequisite to deform the dispersed droplet and form the oriented crystal structure is the shear field. So an attempt was made to correlate the dispersed phase morphology, crystalline morphologies, and shear rate. The shear rate, estimated via the capillary number, across the thickness of the parts molded by MMMIM was bimodal. Even if the coalescence and relaxation of the dispersed phase during and after mold filling cannot be ignored, both the highly dispersed PS domains and the highly ordered crystal structure of PE showed in the regions with the maximum calculated shear rate, which is consistent with the generally accepted theories that strong shear flow is favorable to the formation of the oriented structures. POLYM. ENG. SCI., 54:2345–2353, 2014. © 2013 Society of Plastics Engineers

Polyethylene blends with bimodal molecular weight distribution were prepared by blending a high molecular weight polyethylene and a low molecular weight polyethylene in different ratios in xylene solution. The blends and their components were characterized by the high temperature gel permeation chromatograph (GPC), different scanning calorimetry (DSC), and small amplitude oscillatory shear experiments. The results showed that the dependence of zero-shear viscosity (η0) on molecular weight followed a power law equation with an exponent of 3.3. The correlations between characteristic frequency (ω0) and polydispersity index, and between dynamic cross-point (Gx) and polydispersity index were established. The complex viscosity (η*) at different frequencies followed the log-additivity rule, and the Han-plots were independent of component and temperature, which indicated that the HMW/LMW blends were miscible in the melt state. Moreover, the thermal properties were very similar to a single component system, suggesting that the blends were miscible in the crystalline state. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Two commercial polyethylene samples, linear high-density polyethylene (HDPE) and branched linear low-density polyethylene with almost the same molecular weight distribution but different contents of short-chain branching (SCB) were melt blended based on the consideration of practical application. Dynamic rheology analysis indicated good compatibility of all the blends with different compositions. Common differential scanning calorimeter (DSC) tests and successive self-nucleation and annealing (SSA) treatment showed several interesting phenomena. First, without consideration of the effect of molecular weight and molecular weight distribution impact, co-crystallization occurred at all ratios even the two components had a considerable difference in SCB distribution. Second, in SSA curves the area of the first two melting peaks, i.e., the amount of the thick lamellas of the two components showed an obvious positive deviation with the increase of HDPE content owing to the crystal perfection improved by the co-crystallization. Essential Work of Fracture tests proved the co-crystallization effects had a positive effect on the improvement of the resistance to crack propagation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The effect of poly (lactic acid) (PLA) on the crystalline phase transition of poly (vinylidene fluoride) (PVDF) from α- to β-phase under uniaxial stretching for immiscible PVDF/ PLA blends was investigated. The typical sea-island structure in the blends was found to facilitate the necking of PVDF and the transition from α- to β-phase due to the local stress distribution during stretching. The crystalline phase transition of PVDF in the blends is temperature-dependent and is affected by the content of PLA. The highest content of β-phase, F(β), was achieved in the samples stretched at 60°C, while the effect of PLA content on the crystalline phase transition of PVDF is more complex. F(β) increases slightly when the sample with a PLA content no more than 15 wt % is stretched at 60, 80, and 100°C, and decreases sharply for the sample containing 20 wt % PLA; in addition, the sample containing 10 wt % PLA exhibits the highest F(β) no matter what the stretching temperature is. The mechanism of the crystalline phase transition of PVDF during the stretching is interpreted from energy barrier of the transition from α- to β-phase and the morphological structures in the blends. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The effect of three kinds of graphitic fillers with distinct morphologies, natural graphite sheets (NGs), chemically reduced graphite oxide sheets (CRGs) and thermally reduced graphite oxide sheets (TRGs), on the crystallization, rheological behavior and mechanical properties of poly(vinylidene fluoride) (PVDF)-based composites has been investigated comparatively. NGs exhibit smooth surface and multilayer-stacked structure; most CRGs are in the form of aggregates that are restacked during reduction; while TRGs show a wrinkled topography of relatively thin graphene sheets. The introduction of these graphitic fillers into the PVDF matrix contributes differently to the crystallization, rheological behavior and mechanical properties of the composites. Among them, TRGs show the greatest strengthening effect, as revealed by rheological and dynamic mechanical responses. Compared with chemical reduction technology, thermal reduction is a more economical, environmentally friendly and scalable approach to prepare functionalized graphene sheets. Copyright © 2012 Society of Chemical Industry

A new kind of β nucleating agent, multi-wall carbon nanotube (MWCNT)-supported calcium pimelate was introduced into polyamide 6 (PA 6)/isotactic polypropylene (iPP; 10/90 by weight) blend and the thermal properties, morphology, and mechanical properties were investigated. The results showed that β-iPP appeared at low content of MWCNT-supported calcium pimelate which surmounted the α-nucleating effect of PA 6 for iPP, and the content of β-iPP increased with increasing content of MWCNT-supported calcium pimelate. The impact strength, elongation at break, and flexural modulus were improved with increasing content of MWCNT-supported calcium pimelate without significantly deteriorating the tensile strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Polyvinylidene fluoride (PVDF)/multiwalled carbon nanotubes (MWCNTs) nanocomposites were prepared by solution blending method, and the melt viscoelastic behavior of the composites was studied. The results showed that the dispersion of MWCNTs in the matrix and the surface characteristic of MWCNTs had a profound influence on the melt rheological behaviors of the nanocomposites. Generally, the dynamic storage modulus (G′) of the nanocomposites with well dispersed MWCNTs was greatly improved. However, PVDF/MWCNTs-g-OH nanocomposites exhibit more significant solid-like behavior than PVDF/MWCNTs nanocomposites at an MWCNTs loading of 2 wt % or higher, even though the dispersion of MWCNTs-g-OH is poorer than that of virgin MWCNTs owing to the higher interfacial interactions from van der Waals force and hydrogen bonding. In this case, the influence of the interfacial interactions on the melt rheological properties was stronger than the dispersion state. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Antiviral prophylaxis has become a commonly used strategy for prevention of cytomegalovirus (CMV) disease in seronegative recipients of an organ from a CMV-seropositive donor (D+ R−) and has typically been given for 3–6 months post transplant (1). Despite significant reductions in the incidence of CMV with this approach, 20–40% of D+ R− patients still develop CMV disease after discontinuation of antiviral prophylaxis. CMV disease in this setting (termed ‘late-onset CMV’) is an important clinical problem that is associated with significant morbidity (2–4). Optimal approaches for preventing late-onset disease have not been fully defined, but have included extending the duration of prophylaxis, viral monitoring and preemptive therapy after discontinuation of prophylaxis, or enhanced surveillance for clinical symptoms and early treatment. Although it is well established that D+ R− transplant patients as a group are at significantly higher risk of late-onset CMV disease compared with seropositive (R +) patients, the risk factors within the D+ R− group have not been well defined. If specific clinical or transplant variables predictive of late-onset CMV disease could be identified within this group, it might be possible to design a more rational targeted CMV prevention strategy for those D+ R− patients at greatest risk. We are aware of only 4 previously published studies that analyzed risk factors for late-onset CMV in D+ R− kidney transplant recipients who received antiviral prophylaxis (4–7). Among these, 2 combined results of kidney with other transplant recipients (4, 6), making it difficult to determine which risk factors might specifically be related to kidney transplant without confounding by the other organ transplant. Thus, given the limited data regarding the risk factors for late-onset CMV disease in D+ R− kidney transplant recipients who receive antiviral prophylaxis, we retrospectively assessed the association of multiple demographic and transplant variables with CMV disease in a cohort of adult D+ R− kidney transplant recipients at a single US kidney transplant center.

A series of bimodal high density polyethylene (PE) with different molecular weight distributions (MWDs) were prepared by melt blending, and the fitting multipeaks on Gaussian were used to analyze the MWD curves, and the ratio of the areas under unimodal curves was as a tool to characterize the MWD; the phase behaviors and rheological behaviors were studied by dynamic rheological. The results showed that homogeneous bimodal high density PEs could be successfully prepared via melt blending, and the bimodal characteristic could be adjusted as expected. For samples with the MWD peak positions unvaried, the storage modulus, complex viscosity, and zero-shear viscosity decreased rapidly with the value of AL/U increasing. Especially in the low frequency region, the loss modulus surpassed the storage modulus (G″ > G′) when AL/U > 10.17 and the dynamic cross-point Gx appeared and increased with increasing AL/U, with an increasing extent much larger than that due to the width of MWD. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The mechanical and thermal characteristics and morphology of polyamide 6 (PA6)/isotactic polypropylene (iPP) blends (10/90 w/w) prepared with different processing procedures and incorporated with an aryl amide nucleating agent, a kind of β-nucleating agent (β-NA) for iPP, were investigated. The yield strength and flexural modulus of the blends decreased as β-NA was introduced into the blends, whereas the impact strength and elongation at break improved. The crystalline structures of the blends closely depended on (1) the processing conditions and (2) competition between the β-nucleating effect of β-NA and the α-nucleating effect of PA6 for iPP. Scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction were adopted to reveal the microstructures of the blends. At a low β-NA content (

The effect of repetitive processing on the mechanical properties and fracture toughness of dynamically vulcanized isotactic polypropylene/ethylene-propylene-diene rubber blends (TPVs) with and without addition of β-nucleating agent (β-NA) was studied. The results showed that the repetitive processing did not cause much loss in the mechanical properties of TPVs, especially for TPVs with β-NA, and TPVs with β-NA showed better performance stability than TPVs without β-NA. Essential work of fracture (EWF) approach was used to study the fracture behavior, and the results showed that the value of we (the specific essential work of fracture) of TPVs without β-NA showed a significant decrease while that of TPVs with β-NA almost kept constant after repetitive processing. Differential scanning calorimetry and wide-angle X-ray diffraction were used to study the variation of crystalline structures, and the results indicated that the repetitive processing showed no significant influence on the crystalline structures of TPVs, and the β-NA maintained high-nucleating efficiency after repetitive processing. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Four kinds of ethylene-proplene-diene/maleic anhydride compatibilized polyamide 6/polypropylene samples were prepared with different mixing sequences and showed significant differences in the Izod impact strength. The morphological features of these samples were characterized with scanning electron microscopy, and a heterogeneous dispersion of the compatibilizer in the injection-molded samples was observed; this was related to the shear field in the skin and subskin layers during injection. A parameter, the transfer energy, is put forward to interpret the dispersion of the compatibilizer in the injection-modeled blens, and the results show that the transfer energy is a key factor in determining the transfer of the compatibilizer

Thermoplastic vulcanizates (TPVs) based on PP and EPDM (the ratio is 5:5) with different crosslinking degrees were prepared using different contents of phenolic resins, and then blended with polyamide 6 (PA6). The results indicated that with an increase in crosslinking degree, the double yielding phenomenon in PA6/TPV blends became more distinct, the yield stress of the first yield point and the yield stress difference of the two yield points decreased; however, the yield strain of the first yield point did not change with the increasing crosslinking degree of the TPV, but the yield strain of the second yield point increased, resulting in a more broadened yield region. The SEM results showed that with an increase in the crosslinking degree of TPV, the diameter of TPV increased in the core layer, and the orientation degree of TPV in the skin and subskin layer deceased, accompanying with a decrease of the ratio of length to diameter (L/D) of the droplets. The morphology evolution of the PA6/TPV blend during the tensile test was also studied, and the results agreed well with the model we proposed

While much research has suggested that the integrity of the blind is compromised in psychotropic drug trials, little research has been conducted on blinding in substance abuse trials. The current study examines the integrity of the blind in an outpatient pharmacotherapy trial investigating the effectiveness of amantadine and propranolol in treating cocaine addiction. Results suggest that neither nurses (N = 174, kappa = 0.08, p = 0.22) nor participants (N = 163, kappa = 0.09, p = 0.26) could accurately predict treatment assignment. Furthermore, nurses' perceptions of treatment assignment were significantly related to trial completion, medication compliance, and cocaine use--results that may have training implications for medical personnel.

The effect of α- and β-nucleating agents (NA) of various amounts on the fracture behavior of polypropylene-co-ethylene (CPP) was evaluated using the essential work of fracture (EWF) method. The specific EWF values of CPPs incorporated with α-NA of different amount were all lower than that of pure CPP, while the specific nonessential work of fracture was the highest at relative low α-NA loading (0.1 wt %), and then decreased with further increasing amount of α-NA. Similar trend of variation was observed with increasing amount of β-NA in CPP, and it was found that the variation of Kβ for β-NA nucleated CPP versus NA content accorded well with the EWF versus NA content, which indicated that the addition of β-NA could lead to effectively increased β-crystal content and consequently improved fracture resistance of CPP. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

A group of high density polyethylene with different molecular weight was prepared by melt blending two kinds of HDPE with weight average molecular weight of 3.2 × 105 g/mol and 7.2 × 105 g/mol, respectively. The fracture behavior of injection molded specimens of these samples was investigated by Izod impact test and scanning electron microscopy. The results show that the variations of impact toughness of injection molded HDPE could be reflected directly by the evolution of morphology of fracture surface as molecular weight increases. Higher molecular weight led to higher impact toughness, due to both thickened oriented shear zone which could enhance the crack resistance and depressed two types of fracture behavior (tearing-brittle fracture and heat softening/melting fracture) with low energy consumption. Fracture behavior in different position of injection molded HDPE shows different molecular weight dependence. The impact toughness at far-gate-end increases with increasing molecular weight, while the impact toughness at near-gate-end, especially for the blends, almost keeps constant within a certain range of molecular weight. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

In this study we have investigated the effect of mold temperature and moisture content on double yielding of virgin polyamide 6 (PA6) uniaxially deformed at room temperature. The experimental results have revealed that, to a certain extent, a limited increment in both mold temperature and moisture content will make the second yield process become more apparent. However, the double yielding behavior will disappear totally in the case of much higher mold temperature and moisture content. Instead, a typical single sharp yield or brittle fracture will be present in the former case, while in the latter case the samples only display a very broad yield, similar to a rubber-like deformation. Maybe two critical states will be in existence in PA6 exhibiting double yielding behavior, and the critical states are probably relevant with the concentration of the interlinks and intralinks, the lamellae perfection and the crystallite size. Particular emphasis should be placed on the role of interlinks and intralinks when considering the origin of double yielding of virgin PA6 since these links affect the stress transfer significantly. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1217–1225, 2007

The crystallization and phase morphology of the injection-molded isotactic polypropylene (iPP)/syndiotactic polypylenen (sPP) blends were studied, focusing on the difference between the skin layer and core layer. The distribution of crystallinity of PPs in the blends calculated based upon the DSC results shows an adverse situation when compared with that in the neat polymer samples. For 50/50 wt % iPP/sPP blend, the SEM results indicated that a dispersed structure in the skin layer and a cocontinuous structure in the core layer were observed. A migration phenomenon that the sPP component with lower crystallization temperature and viscosity move to the core layer, whereas the iPP component with higher crystallization temperature and viscosity move to the skin layer, occurred in the iPP/sPP blend during injection molding process. The phenomenon of low viscosity content migrate to the low shear zone may be due to the crystallization-induced demixing based upon the significant difference of crystallization temperature in the sPP and iPP. This migration caused the composition inhomogeneity in the blend and influenced the accuracy of crystallinity calculated based upon the initial composition. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2948–2955, 2007

The influence of annealing conditions on the fracture behavior of poly(propylene-block-ethylene) sheets was investigated by means of the essential work of fracture method, and was complemented by the study of the effect of annealing on crystal structure, using differential scanning calorimetry. It was shown that both the crystal perfection degree and crystallinity could be improved substantially as annealing temperature (Ta) increased, while the prolonged annealing time at 80°C mainly resulted in the improvement of crystallinity. The reasons for an increase in the specific essential work of fracture and a decrease in the specific plastic work item as crystal perfection degree and crystallinity grew are discussed. The displacement to failure of double edge notched tension specimens decreased gradually with increasing Ta, and the double-plastic zone could be observed in all specimens. In addition, a novel method to aid the accurate measurement of intense stress-whitening outer plastic zone height by adjustment of illumination conditions is proposed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3438–3446, 2007

The effects of expandable graphite (EG) of different particle sizes, on the fire-retardant properties of high-density rigid polyurethane foam (RPUF) (0.45 g cm−3) were studied. Samples of EG with different particle sizes were obtained by pulverization in an ultra-high-speed mixer for 4 and 13 min, respectively. It was shown that as received (EG0) and 4 min pulverized EG (EG4) efficiently improved the fire-retardant properties of RPUF composites, while 13 min pulverized EG (EG13) did not. The char of the burned composites filled with EG0 and EG4 covered the whole surface of the samples and formed a complete physical barrier. This barrier material prevented combustible gases from feeding the flame and also isolated oxygen efficiently from the burning material. EG13 did not produce enough char to cover the whole surface of the burning sample, resulting in poor fire-retardant property of the RPUF composites. Thermal degradation tests of the foams by thermogravimetric analysis indicated that EG showed negligible effects on the thermal stability of the RPUFs. Copyright © 2006 Society of Chemical Industry

The morphology and mechanical properties of the in situ microfibrillar blend based on isotactic polypropylene (iPP) and poly (phenylene sulfide) (PPS) were examined. The microfibrillar PPS/iPP blend was prepared through a slit-die extrusion, hot stretching, and water quenching process. Morphological observation indicated that the well-defined PPS microfibrils were achieved by the method used in this study, which provided a promising method for both PPS and PP recycling. The morphology study showed that the minimum diameter of PPS phase was independent of PPS concentration. The diameter of most PPS fibrils in the microfibrillar blend was unexpectedly comparable to that of the PPS particles in the common blend at the same PPS content. The tensile strength of microfibrillar blend was higher than that of common blend, indicating the mechanical enhancement of microfibrillar processing to the PPS/iPP blend. The tensile strength of the microfibrillar blend also increased with stretching. POLYM. ENG. SCI., 45:1303–1311, 2005. © 2005 Society of Plastics Engineers

The effect of the glass bead (GB) size and bead content on the fracture behavior of GB-filled linear low-density polyethylene (LLDPE) composites was evaluated by means of the essential work of fracture (EWF). The results indicated the specific EWF (we) is lower for the composites than that of pure LLDPE and the obtained we values do not show significant differences for the filled samples with different GB diameters. The non-EWF or plastic work (βwp) also decreased with the addition of GBs, indicating that less energy is absorbed during the fracture process for the composites filled with different diameter GBs. For the composites filled with GBs of different contents, the we decreased with increasing GB contents and the βwp that was higher than that of pure LLDPE at relatively low contents also decreased with the content of GBs. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1781–1787, 2006

In situ microfibrillar poly(ethylene terephthalate) (PET)/polyethylene blends (MRB) were successfully fabricated by the slit-die extrusion-hot stretching-quenching. The morphology of this new material is mainly influenced by the composition and the hot stretching. Appropriate PET concentrations and a comparatively high hot stretching ratio could facilitate the fibrillation of PET domains during processing. The expression employed for prediction of the tensile strength for the microfibrillar blend was proved to be desirable. The prediction was, generally, in agreement with the experimental results, although the values of some parameters were approximated.

An in-situ microfibrillar blend based on poly(ethylene terephthalate) (PET) and polyethylene (PE) was fabricated through slit die extrusion, hot stretching, and quenching. The morphological characteristics of the PET phase, such as diameter and its distribution, which were observed after the matrix was etched away, appear to be dependent on the hot stretch ratio at a fixed blend composition. The increase of the hot stretching ratio makes the PET particles change from spheres and ellipsoids to rodlike particles, and finally to well-defined microfibers. The fracture toughness of the in-situ microfibrillar blend was evaluated using deeply double-edge notched tension (DDENT) specimens according to the essential work of fracture procedure. Initially, the increase of hot stretch ratio makes the specific essential work of fracture (we) rise. A maximum we appears at 25.4. Further increase of hot stretch ratio causes a slightdecrease of we. On the other hand, it shows that lower hot stretch ratios make the specific non-essential work of fracture (wp) rise slightly. As it exceeds 6.4, wp decreases substantially. It was believed that the characteristics of the PET domains were responsible for the fracture behaviors of the in-situ microfibrillar blend. Polym. Eng. Sci. 44:2165–2173, 2004. © 2004 Society of Plastics Engineers.

This study describes the morphology and nonisothermal crystallization kinetics of poly(ethylene terephthalate) (PET)/isotactic polypropylene (iPP) in situ micro-fiber-reinforced blends (MRB) obtained via slit-extrusion, hot-stretching quenching. For comparison purposes, neat PP and PET/PP common blends are also included. Morphological observation indicated that the well-defined microfibers are in situ generated by the slit-extrusion, hot-stretching quenching process. Neat iPP and PET/iPP common blends showed the normal spherulite morphology, whereas the PET/iPP microfibrillar blend had typical transcrystallites at 1 wt % PET concentration. The nonisothermal crystallization kinetics of three samples were investigated with differential scanning calorimetry (DSC). Applying the theories proposed by Jeziorny, Ozawa, and Liu to analyze the crystallization kinetics of neat PP and PET/PP common and microfibrillar blends, agreement was found between our experimental results and Liu's prediction. The increases of crystallization temperature and crystallization rate during the nonisothermal crystallization process indicated that PET in situ microfibers have significant nucleation ability for the crystallization of a PP matrix phase. The crystallization peaks in the DSC curves of the three materials examined widened and shifted to lower temperature when the cooling rate was increased. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 374–385, 2004

The hot stretching of thick, extruded sheets at high temperatures is a very important process in the production of finished biaxially oriented polypropylene (BOPP) films with special inner structures. Through a simulation of hot stretching in the machine direction (MD) of the processing of BOPP films, it was found that at high temperatures, the stretching ratio greatly influenced the obtained crystalline structure, as observed by differential scanning calorimetry (DSC). Also, in MD hot stretching, the crystallinity increased by an average of 20%. Wide-angle X-ray diffraction patterns of extruded sheet samples with and without stretching confirmed the structural changes shown by DSC, and the results proved that β-crystal modification did not occur during the MD hot-stretching process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 686–690, 2003

An in-situ microfiber-reinforced composite (MRC) based on polyethylene (terephthalate) (PET) and polyethylene (PE) was prepared by slit die extrusion followed by hot stretching. Test specimens were prepared by injection molding at the processing temperature of the PE matrix. At this temperature, far below the melting temperature of PET, the PET phase is solid and able to keep its shape during processing. The morphological characteristics of the dispersed PET phase in the blend, at a fixed weight composition (15:85) of PET and HDPE, were dependent upon the hot stretching ratio. When the hot stretching ratio was increased from 1 (no stretching) to 47.62, the PET particles changed from spheres and ellipsoids to rodlike particles and finally to microfibers. The maximum and average diameters of the PET particles decreased steadily, while the minimum fiber diameter remained constant. The tensile modulus and strength of PET/PE blends were significantly enhanced with increasing hot stretching ratio, indicating that the microfibers have good reinforcement. Ultimate elongation decreased with increasing hot stretching ratio and there was a critical hot stretching ratio above which a ductile-brittle transition occurred.

Infrared spectra of polyamide-6 (PA6) with and without epoxidized natural rubber (ENR) are presented. The influence of ENR used as a compatibilizer on the morphologies, crystallizability, mechanical properties, and thermal behavior of the polyamide-6/polyolefins (PO) blends are studied. The infrared spectra suggest that under normal processing conditions, the carboxyl end groups of PA6 could chemically react in situ with the epoxy groups of ENR, and ester groups are created. This means that the PA6-ENR grafting copolymer could be obtained during processing. All the morphological characterizations and thermal analyses show that the compatibility of PA6/PO blends is obviously improved by ENR because the copolymer increases the interaction between PA6 and PO. It is also found that the toughness of PA6/PO blends increase significantly after using ENR, while the tensile strength and the softening temperature of PA6/PO blends have almost no change. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 398–403, 2003

The overall electrocatalytic activity toward hydrogen evolution reaction for layered transition metal dichalcogenides is governed by their intrinsic activity, the corresponding density of active sites, and the electron transfer resistance. Here, nanoengineering strategies to scale down both the lateral size and thickness of layered 1T-TiS2 powder to quantum dots (QDs) by bath sonication and probing sonication incision are employed. Uniform lateral size of 3–6 nm in the resulting QDs enhances the density of edge sites while the atomic layer thickness (1–2 nm) facilitates the electron transfer from the substrate to the edge sites. The obtained TiS2 QDs exhibit superior hydrogen evolution reaction activity over TiS2 nanosheets and MoS2 QDs prepared by the same method. The turnover frequency of TiS2 QDs with a small loading of 0.7 ng cm−2 in an optimal deposition on electrode reached ≈2.0 s−1 at an overpotential of −0.2 V versus RHE, several orders of magnitude higher than TiS2 nanosheets (0.01 s−1) and MoS2 QDs (0.07 s−1).

During the melt second flow process, the synergetic effect of intense shear and polyamide 6 (PA6) microfibrils finally results in the massive formation of highly oriented crystalline structures in the entire thickness of high density polyethylene (HDPE)/PA6 microfibril blend. Interestingly, not only does the small microfibril induce HDPE crystallization to form typical hybrid shish–kebab structure, but the large microfibril (about 2 μm in diameter) also induces the formation of local hybrid shish–kebab structure. For the small PA6 microfibril, the oriented HDPE chains caused by the intense shear are absorbed on the whole surface of the microfibril and then a complete polymer underlayer is formed. Subsequently, the crystal nuclei appear on the underlayer, and then the other oriented HDPE chains overgrow from the nuclei in the form of folded chains and grow perpendicular to the microfibril. Finally, the typical hybrid shish–kebab structure is formed. While for the large PA6 microfibril, a few HDPE chains can be still absorbed on the microfibril surface due to the high surface energy of PA6. However, the driving force is insufficient to absorb largely oriented HDPE chains to form complete hybrid shish but only local adsorption layer, so the local hybrid structure is formed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45274.

The reactive blends were prepared by the blending of poly(lactic acid) (PLA) with poly(butylene succinate) (PBS) in the presence of dicumyl peroxide (DCP) as a radical initiator in the melt state. The gel fractions, morphologies, crystallization behaviors, and rheological and mechanical properties of the reactive blends were investigated. Some crosslinked/branched structures were formed according to the rheological measurement and gel fraction results, and the crosslinked/branched structures played the role of nucleation site for the reactive blends. The PLA–PBS copolymers of the reactive blends acted as a compatibilizer for the PLA and PBS phases and, hence, improved the compatibility between the two components. Moreover, it was found that the reactive blends showed the most excellent mechanical properties as the DCP contents were 0.2 and 0.3 phr. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39580.

The melt viscoelasticity, electrical conductivity, and crystallization of poly(vinylidene fluoride)/multiwalled carbon nanotubes (MWCNTs) composites prepared by melt blending with different shear effects were examined. Rheological characterization indicated that the incorporation of MWCNTs substantially affected the viscoelastic behavior of the composites. A visible rheological network of CNTs was detected in the composites with relatively high content of MWCNTs. The electrical conductivity of the composites differed substantially for the composites prepared with different shear effects because of the different dispersion states of the MWCNTs in the composites. The nonisothermal crystallization of the composites revealed that the samples prepared with high shear intensity and long shear time exhibited a higher crystallization peak temperature and crystallinity. Besides, the heterogeneous nucleation effect of the MWCNTs was found to be significantly dependent on the dispersion state, which dominated the crystallization even when the confinement effect of the nanotube network existed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The ternary composites of coal gangue powder encapsulated by ethylene propylene diene monomer (EPDM) filled polypropylene (PP) were prepared to reduce the cost and control the microstructure aiming at high performance cost ratio materials. The result showed that EPDM can not only enhance the interaction between coal gangue powder and the matrix but also promote the dispersion of coal gangue powder. With the addition of coal gangue encapsulated by EPDM, the impact strength of composition dropped greatly, but it still kept about 11 kJ/m(2) when the content of encapsulated coal gangue powder is more than 18 wt%. The tensile strength and fracture toughness (w(e)) also dropped with the addition of encapsulated coal gangue powder, but only a small drop occurred when the content of encapsulated coal gangue powder is less than 18 wt% and great drop emerged when the content is larger than 18 wt%. Compared with coal gangue powder/PP binary composition, the ternary compositions involve higher content of coal gangue powder but present better properties. POLYM. COMPOS., 31:10-17, 2010. (C) 2009 Society of Plastics Engineers