PP Phase Research Articles

Focus zone model and depth determination based on amplitudes of pP phases

Analysis of difficulties connected with determination of crust tectonics seismic events is defined by rupture process. Detailed analysis showed that a set of first arrivals associated with an event contains arrivals generated on different depths. This indicates the existence of several instrumentally defined cofocuses in the focus zone. Consequently, the location algorithm should pick up several more significant by amplitude of fist arrivals. Then, seismic event depth will define that one rising maximal seismic signal. Investigation shoes – first arrivals may be projected into one point on seismic record even if they are generated at different depths. Thus, one impulse of first arrival may correspond to several depths. Hence appears the principal difficulties to determine depth solely using P phases. Solution of the problem is automated determination of time arrivals of depth phases pP. The last should be generated at a certain depth. The event depth is chosen by maximum value depth phase amplitude. Algorithm uses all records during the calculation process at the same time. Moreover it was revealed that local second events after first arrival have been registered. Second events may have time delays restricted by seconds. Second event impulse amplitude may be more than impulse amplitude of really first arrival at given depth. On the whole, a group of local first arrivals are in the frame of the period of base event impulse.

Experimental and theoretical investigation of the effect of physical and chemical compatibilization on the properties of thermoplastic elastomers derived from natural rubber and polypropylene blends

The objective of this research was to improve the compatibility between Natural Rubber/Polypropylene NR/PP blends through physical and chemical compatibilization methods. The physical compatibilization involved the use of epoxidized natural rubber/maleic anhydride-grafted polypropylene (ENR50/PP-g-MA) as a dual compatibilizing agent (CA50), while the process of reactive compatibilization entailed chemically modifying NR and PP phases through the grafting maleic anhydride (MA). Several formulations were prepared by melt mixing using a Brabender plasti-corder. The effects of physical and chemical compatibilization on the technical properties were investigated. FTIR analysis revealed the emergence of two distinctive peaks corresponding to the CO group of MA grafted onto PP and NR chains. FTIR analysis has also confirmed the taking place of reactions between the polar functional groups of PP-g-MA and ENR50. The rheological properties indicated that the viscosity of the NR-g-MA/PP-g-MA is lower than those of the control blend and CA50-based NR/PP system. The mechanical and dynamic mechanical findings corroborated the improvement of interfacial adhesion between NR/PP phases, especially for the NR/PP/CA50 system. SEM examination demonstrated a more uniform dispersion of the PP phase in the CA50-based NR/PP, compared to the control blend and NR-g-MA/PP-MA. NR-g-MA/PP-g-MA exhibits greater miscibility and interaction potential compared to the control NR/PP, and less than NR/(ENR50/PP-g-MA)/PP system. DFT calculations further validate the effect of compatibilization methods on TPE blends. Specifically, Quantum molecular descriptors revealed the role of ENR50/PP-g-MA as an intermediary in facilitating compatibility between NR/PP. These findings indicate that the physical compatibilization method approach using ENR50/PP-g-MA as a dual compatibilizer is a potential compatibilizer for NR/PP.

Enhancement of the rheological, dynamic mechanical, and morphological properties of thermoplastic natural rubber based on NR/PP blends using ENR/PP-g-MA as a compatibilizer

This study investigates the effects of incorporating a 50/50 blend of Epoxidized Natural Rubber/Polypropylene-grafted maleic anhydride (ENR/PP-g-MA) as a compatibilizing agent (CA) for a 70/30 Natural Rubber/Polypropylene (NR/PP) thermoplastic elastomer (TPE) on the technical properties such as structural analysis, rheological, dynamic mechanical and morphological properties. Formulations with varying CA concentrations (5 to 15 phr) were prepared using a Brabender plasticorder at 180°C for 10 min. The structural analysis was examined by Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (1H-NMR). The rheological behavior was examined using a Rubber Process Analyser (RPA). The dynamic mechanical properties were investigated by DMA. Atomic Force Microscopy (AFM) was used for the morphological examination. FTIR analysis confirmed reactions between the MA group in PP-g-MA and the epoxy groups in ENR, resulting in ENR-grafted PP with an ester and acid-based linkage. This reaction was evident during compatibilizer preparation. RPA results showed increased viscosity for both types of CAs compared to their individual values, confirming crosslinking reactions. Higher CA concentrations led to elevated viscosity and storage modulus. DMA results indicated that the compatibilization led to a significant enhancement in the storage modulus of the blends. Moreover, an increase in the glass transition temperatures (Tg) of the blends was produced. AFM examination revealed a more homogenous distribution of the dispersed PP phase for the CA-containing blends compared to the control NR/PP system.

Investigation of Crystallization, Morphology, and Mechanical Properties of Polypropylene/Polypropylene-Polyethylene Block Copolymer Blends.

Polyethylene (PE)-based elastomers are the ideal choice for enhancing the compatibility of polypropylene/polyethylene (PP/PE) blends and improving the mechanical properties of PP-based materials. However, the issue of blend systems lies in the interplay between the crystallization processes. Therefore, we investigated the crystallization behavior during the cooling process of a new generation of PP/PE block copolymers (PP-b-PE) and random polypropylene (PPR, a copolymer of propylene and a small amount of ethylene or an alpha-olefin) blends using in-situ X-ray diffraction/scattering and differential scanning calorimetry (DSC) techniques. We also conducted mechanical performance tests on PPR/PP-b-PE blends at room temperature and low temperature (-5 °C). The results indicate that during the cooling process, the PP phase of PP-b-PE will follow the PPR to crystallize in advance and form a eutectic mixture, thereby enhancing the compatibility of PP/PE. Moreover, the PPR/PP-b-PE blend will form stable β-(300) crystals with excellent mechanical properties. Due to the improved compatibility of PP/PE with PP-b-PE, PE crystals are dispersed within PP crystals, providing bonding that improves the toughness of PPR under the low stiffness failure conditions of PPR/PP-b-PE blends, thereby enhancing their impact performance at low and room temperatures. This research has great significance for both recycling waste plastics and enhancing the low-temperature toughness of PPR.

Mechanism of Low‐Temperature Brittle–Ductile Transition of Polypropylene/Low‐Density Polyethylene Blend Foam under Compressive Stress Caused by Cell Stretching

To enhance the low‐temperature toughness of polypropylene/low density polyethylene (PP/LDPE) blend, which is a crucial blend for polyolefin material with wide applications in frigid regions, the PP/LDPE blend foam with stretched cells is fabricated via a facile injection foaming together with open‐mold stretching process. During the open‐mold stretching, the relatively miscible PP and LDPE chains are debonded, and then the stretched and oriented cells structure with lots of tiny interphase cavities between the PP and LDPE phases and the fine lamellae are formed in the foam system. Such interphase cavities provide an adequate movement space for the frozen PP and LDPE chains and lamellae, and effectively relaxed and transferred stress, which greatly promote the uniform compressive behavior accompanied by the completely compacted cells at −25 °C. Moreover, the compressive fracture surface changes from relatively flat and smooth for the stretched PP foam to obvious yield folds and deformation for the stretched blend foam, and the compressive strain of stretched PP/LDPE blend foam is highly enhanced by a roughly 31%, 53%, and 44% increase than that of PP, PP/LDPE, and stretched PP foam samples, respectively, achieving the low‐temperature brittle–ductile transition for PP.

Unlocking the Potential Use of Reactive POSS as a Coagent for EPDM/PP-Based TPV.

Thermoplastic vulcanizates (TPVs) are multifunctional materials consisting of two or more phases with solid elastomeric properties at room temperatures and fluid-like properties above their melting point. They are produced through a reactive blending process known as dynamic vulcanization. The most widely produced TPV type is ethylene propylene diene monomer/polypropylene (EPDM/PP), which is the focus of this study. The peroxides are mainly selected to be used in crosslinking of EPDM/PP-based TPV. However, they still have some disadvantages, such as the side reactions resulting in the beta chain scission of the PP phase and undesired disproportionation reactions. To eliminate these disadvantages, coagents are used. In this study, for the first time, the use of vinyl functionalized polyhedral oligomeric silsesquioxane (OV-POSS) nanoparticles was investigated as a potential coagent in EPDM/PP-based TPV production via peroxide-initiated dynamic vulcanization. The properties of the TPVs having POSS were compared with the conventional TPVs containing conventional coagents, such as triallyl cyanurate (TAC). POSS content and EPDM/PP ratio were investigated as the material parameters. Mechanical properties of EPDM/PP TPVs exhibited higher values in the presence of OV-POSS, which resulted from the active participation of OV-POSS into the three-dimensional network structure of EPDM/PP during dynamic vulcanization.

QuantifyingP-wave secondary microseisms events: a comparison of observed and modelled backprojection

SUMMARYSecondary microseisms are caused by nonlinear interactions between ocean waves of approximately equal wavelengths and opposite propagation directions. This seismic forcing is evaluated using ocean sea-state hindcast data and further modulated by the bathymetric effect. The numerical ocean model provides a global activity representation of the secondary microseisms, from which we isolate major events. We backprojected teleseismic P-wave propagation into the Earth's mantle to validate these events as effective seismic sources. The ocean model provides spectral amplitude information for modelling microseisms generated seismic wavefield. A comparison of the backprojection for P and PP phases from observed and synthetic microseisms forcing indicates high reliability in the ocean model, at least for major sources. A combination of P and PP phases detected across a global network of stations enables global ocean coverage. We improve backprojection images even further by introducing a two-step stacking for the P phase to address the problem of unbalanced station distribution. Thresholds of microseisms events forces valuable for seismic imaging are determined by comparing backprojections and ocean models for the years 2015 and 2020. Finally, we extracted a catalogue of microseisms events every 3-hr from 1994 to 2020 from the ocean hindcast data set. This catalogue is an intriguing resource for future applications of interferometric imaging at large scale.

How nucleating particles migration affects the fractionated crystallization of isotactic polypropylene/polystyrene immiscible blends

We investigate the inter-phase migration of nucleating particles and their effect on the fractionated crystallization of polypropylene droplets dispersed in an immiscible polystyrene matrix by preparing melt-mixed 90/10 wt% PS/PP blends with selected nucleating agents. Different concentrations of nucleating agents (NAs): Phtalocianene Blue, NA11, Talc, and sodium benzoate, were initially incorporated either in neat PP or in neat PS. Then the different PS/PP/NAs blends were prepared. Contact angles were determined for the neat polymers and the NAs, and the results indicated that, from a thermodynamics point of view, all NAs should remain or migrate to the PS phase. According to SEM observations, a sea-island morphology was obtained that did not vary with NA addition. Hence the results should be independent of differences in the morphology.PP droplets crystallized in neat blends in three well-differentiated crystallization peaks (i.e., fractionated crystallization). The NAs induce a concentration-dependent increase in the high-temperature crystallization peak at the expense of reducing the low-temperature peaks, as droplets become in contact with or contain the NAs. When compared at a constant concentration in one of the phases, the nucleating agents have efficiencies that decrease in the order: Pht Blue ≈NA11>Talc>Sod Benz. Surprisingly, for the three most effective NAs, it was found that adding them initially to the PS phase led to a much higher nucleation efficiency (evaluated in terms of increases in peak crystallization temperature) than adding them to PP. This indicates that these NAs, initially present in the PS phase, migrate to the interface or to the bulk of the PP phase (against thermodynamics). Sod Benz was the only exception, as it shows a higher thermodynamic affinity to the PS phase. We explain the migration of most particles from the PS phase to the phases’ boundary or to the bulk of the PP droplets by considering that kinetic factors dominate the behavior, as, from a rheological perspective, the minor component (PP) always displays a lower viscosity than the matrix component (PS) under the chosen mixing conditions.

Innovative polypropylene based blends by in situ polymerization of a polyimide dispersed phase by reactive extrusion

Polypropylene/polyimide (PP/PI) blends were synthesized by reactive extrusion with the in situ polymerization of the polyimide phase in presence of maleic anhydride grafted polypropylene (PP-g-MA) as a compatibilizer. Blends were reactively processed in a twin-screw extruder at 200 °C, with the PI content varying from 10 to 40 wt%. Examination of morphology by scanning electron microscopy (SEM) depicted a fine sub-micrometer dispersion of the polyimide phase ranging from 170 to 250 nm in diameter, for all PI concentrations. The advantage of the in situ approach compared to the more classical dispersion process was clearly demonstrated. The in situ synthesized PI phase was characterized by NMR and FTIR after separation by Soxhlet selective extraction. Differential scanning calorimetry (DSC) analysis of the blends showed no modifications of PP crystallinity with the addition of PI. Rheological behaviors showed a significant impact of the polyimide phase on the storage modulus with the appearance of a secondary storage modulus plateau at low frequencies. Thermogravimetric analyses evidenced an improvement of the thermal stability of the blends, with an increase of the decomposition temperature up to 35 °C depending on the polyimide content. Mechanical properties were also improved due to the high mechanical strength of the polyimide phase, with an increase in Young's modulus up to +35 % for the highest polyimide content. • Polyimide was in situ synthetized in PP phase. • A fine sub-micrometer dispersion of the polyimide phase ranging from 170 to 250 nm was obtained. • Increase in Young's modulus up to +35% for the highest polyimide content.

Seismic sources of InSight marsquakes and seismotectonic context of Elysium Planitia, Mars

Since early 2019, the InSight mission has proven that Mars is seismically active, with more than 900 seismic events recorded. Among them, several events have characteristics close to terrestrial tectonic earthquakes. Most of these events are located on the major graben system of Cerberus fossae and, a little further north, on the secondary system of Grjotá Valles. In this study, we invert the seismic moment tensors for nine of these tectonic marsquakes characterized by high quality data. Seven of them are located on Cerberus fossae/Grjotá Valles and two of them are located near the Martian dichotomy. The moment tensors allow us to interpret the nature and depth of the seismic sources at the origin of these events. In our approach, we invert the P and S body waveforms, the PP, SS, PPP and SSS secondary phase maximum amplitudes and we look for solutions with surface waves weaker than the Martian noise. From our results on moment tensors, we determine that all our events have been triggered at moderate depths of 15–36km. We deduce that the seven events located on Cerberus fossae have geometries similar to the fractures and are generated by tectonics. This activity is supposed to result from the reactivation of previous faults and fractures, which would have been initially induced by the propagation of volcanic dikes at depth. The two dichotomy events are due to deep compressive fracturing of the Martian lowlands. They are therefore triggered by the planetary thermal contraction. Our results are in strong agreement with recent studies on the event depths and on the previous moment tensors calculated for two events.

The Far Side of Mars: Two Distant Marsquakes Detected by InSight

Abstract For over three Earth years the Marsquake Service has been analyzing the data sent back from the Seismic Experiment for Interior Structure—the seismometer placed on the surface of Mars by NASA’s InSight lander. Although by October 2021, the Mars seismic catalog included 951 events, until recently all these events have been assessed as lying within a radius of 100° of InSight. Here we report two distant events that occurred within days of each other, located on the far side of Mars, giving us our first glimpse into Mars’ core shadow zone. The first event, recorded on 25 August 2021 (InSight sol 976), shows clear polarized arrivals that we interpret to be PP and SS phases at low frequencies and locates to Valles Marineris, 146° ± 7° from InSight. The second event, occurring on 18 September 2021 (sol 1000), has significantly more broadband energy with emergent PP and SS arrivals, and a weak phase arriving before PP that we interpret as Pdiff. Considering uncertain pick times and poorly constrained travel times for Pdiff, we estimate this event is at a distance between 107° and 147° from InSight. With magnitudes of MwMa 4.2 and 4.1, respectively, these are the largest seismic events recorded so far on Mars.

A Global Centroid Single Force Catalog of P‐Wave Microseisms

AbstractP‐wave microseisms are excited by ocean swell activities. The recent development of an ocean wave model allows us to compare them quantitatively. For the comparison, a single force at a centroid location can characterize the seismic excitation. A beamforming method is feasible for locating the centroids efficiently. However, the required plane wave assumption reduces the accuracy for a large aperture array. The lack of information on the wavefront curvature also makes P and PP phases indistinguishable. To utilize information on the curvature, we developed the auto‐focusing method as a natural extension of beamforming: (a) We estimated the slowness vector and the wavefront curvature by a grid‐search method, which maximizes the beam power. (b) We iteratively update the values based on the perturbation theory. (c) Based on the classified phase according to the wavefront curvature and the slowness, we locate the centroid from the slowness vector with corrections for a global 3‐D P‐wave velocity structure. We also infer the centroid‐single‐force (CSF) from the beam power. We applied this method to the vertical components of seismic records at approximately 780 Hi‐net stations in Japan from 2004 to 2020. We also compare the CSF catalog with a synthetic CSF catalog based on a numerical ocean wave model: WAVEWATCH III. Both catalogs generally show similar temporal‐spatial patterns of centroids. The amplitudes of CSF are consistent with each other, although the seismic signal‐to‐noise ratio limits the detected events. The ocean wave model cannot explain significant activities in the Gulf of Carpentaria.

Extensional rheology and CO2 foaming of thermoplastics vulcanizates: Influence of the crosslinking chemistry

The objective of this study is to investigate the ability of thermoplastic vulcanizates (TPVs) (materials based on PP/EPDM blend) to foam under CO2 batch conditions. The EPDM phase, which is dispersed into the PP phase, was dynamically crosslinked either by a phenolic resin (Resol) or by a radical peroxide (dicumyl peroxide). The results show an influence of the crosslinking chemistry on the extensional viscosity of the TPV. Regarding radical chemistry, the peroxide induces polypropylene degradation by β-scission reaction during the dynamic crosslinking process. As a result, the ability of the TPV to deform under extensional flow (Hencky deformation at break <0.5) is greatly reduced. On the contrary, the Resol-based TPV has demonstrated a non-linear viscosity behaviour (strain hardening) and a great ability to deform (Hencky deformation at break >1.5). This unexpected result for a non-homogeneous system can be explained by the confinement of the PP phase between EPDM nodules which gives to the PP chains a gel rheological behaviour. In addition, the influence of the addition of carbon black filler has also been studied. Finally, the relationship between extensional viscosity and physical foaming has been investigated. As for a homogeneous polymer, the extensional viscosity has been proved to be a key factor to estimate the foaming behaviour of complex systems like TPV. Hence, the importance of non-linear viscosity for a multi-phasic polymer to ensure foaming ability has been demonstrated.

Enhancement of thermoelectric and mechanical properties of thermoplastic vulcanizates (TPVs) with hydroxylated graphene by dynamic vulcanization

Abstract In order to obtain higher thermoelectric and mechanical properties in nonpolar thermoplastic vulcanizates (TPVs), the butyl rubber/polypropylene (TPVs)/hydroxylated graphene (HGE) composites with nanosheet network were prepared through masterbatch technique and based on thermodynamic calculations, using polypropylene-graft-maleic anhydride (PP-MA) as a compatibilizer. The Fourier transform infrared (FTIR) and Raman spectra revealed the introduced maleic anhydride group on PP-MA can form strong interfacial interaction with hydroxyl-containing functional groups on HGE. Morphology study indicated the rubber particles in the composites occupied the most volume of the PP phase, as expected to hinder the aggregation of HGE and form the effective nanosheet network. The nanosheet network can be combined with the butyl rubber (IIR) cross-linked particles during the dynamic vulcanization process to improve the interface bonding between PP and IIR, thus increasing the tensile strength of TPVs. The prepared TPVs/HGE composites have significantly improved in mechanical properties, thermal properties and dielectric properties, which provides a guarantee for their potential application as multifunctional TPVs polymers.

Improving depth estimations of African earthquakes using teleseismic data, and influence for the East-African rift seismic hazard characterization

SUMMARY Well-constrained earthquake depth estimations are important for seismic hazard determination. As local networks of the East-African Rift are usually too sparse for reliable depth estimations, we used detections of pP and sP phase arrivals (the so-called depth phases) at teleseismic distance to constrain earthquake depths in this region. We rely on a fully automatic Cepstral analysis approach, first validated at the global scale using the ISC-EHB catalogue, then applied on the East-African seismicity. We investigated 9575 earthquakes from magnitude 2 since 2005 which allows us to constrain the depth estimation of 584 events with magnitude mainly above 3.5, complemented by 139 reliable depth estimations from previous studies based on teleseismic data as well. To ensure a final catalogue as complete as possible, we also identified from regional catalogues 113 earthquakes assumed to be well constrained, based on network geometry empirical criteria. Thanks to this study, we finally propose new earthquake depth distributions for the seismic source zonation defined by Poggi et al., in order to estimate the seismic hazard of the East African Rift region. Including those new distributions in the source models leads to significant changes of seismic hazard assessments results.

Evolution of the electrical resistivity at rest and during oscillatory shearing of co‐continuous morphology (PP/PMMA)/MWCNT systems

AbstractIn this work, a modified parallel‐disks configuration on a strain‐controlled ARES rheometer (TA Instrument) was used to study the evolution of the electrical resistivity at rest and during oscillatory shearing of a co‐continuous immiscible polymer blend morphology based on polypropylene and /polymethyl(methacrylate) (PP/PMMA) in which various amounts (0–3 wt%) of multiwall carbon nanotubes (MWCNT) were added. The co‐continuity of both PP and PMMA phases allowed the buildup of a conductive network due to the preferential localization of the conductive MWCNT at the interface between PP and PMMA. Under a stepwise increase of the oscillatory strain amplitude below a critical value (γc = 6.3%), a significant decrease in the electrical resistivity was observed for MWCNT concentrations above the percolation threshold (0.3 wt%) due to the conductive paths induced by both thermal (Brownian) motion and oscillatory shearing. However, for deformation amplitudes higher than γc, the resistivity increased due to the destruction of the MWCNT paths induced by the large deformation imposed on the PP/PMMA interface. These observations were also confirmed by the evolution of the storage modulus (G′) which remained constant for γc < 6.3% (linear viscoelastic regime), while the values decreased above γc due to the destruction of the system's morphology.

Carbon nanotubes interaction with amorphous and semi‐crystalline domains of polypropylene in melt‐mixed composites: Influence of multiwall carbon nanotubes agglomerate and their modifications

AbstractPolypropylene (PP) and multi‐walled carbon nanotubes (MWCNTs) composites were prepared by melt‐mixing with two types of MWCNTs of varying agglomerate size. Agglomerate dominated dispersion was observed in the PP matrix, wherein N‐MWCNTs exhibit a finer dispersion as compared to D‐MWCNTs. Further, MWCNTs were encapsulated by Li‐salt of 6‐amino caproic acid in various proportions along with PP‐g‐maleic anhydride in order to achieve finer MWCNTs dispersion. Thermogravimetric analysis exhibited an increase in onset of degradation temperature and higher residual weight (%) at 500 °C of PP with increased MWCNTs concentration, which suggests the formation of a thicker “interphase.” Glass transition temperature of the PP phase was increased monotonically as a function of unmodified MWCNTs concentration, which suggests a strong interfacial interaction between PP and MWCNTs. An extensive analysis was carried out with modified MWCNTs based PP composites. Moreover, MWCNTs act as a strong hetero‐nucleating agent manifesting in smaller spherulite size of PP, wherein bulk crystallization temperature is increased to ~130 °C of the PP phase at 5 wt% MWCNTs content. The influence of unmodified and modified MWCNTs on the interaction between the PP chains and MWCNTs in the amorphous phase as well as in the crystalline domains are analyzed in PP/MWCNTs composites.

Lithospheric Architecture of the Paranapanema Block and Adjacent Nuclei Using Multiple‐Frequency P‐Wave Seismic Tomography

AbstractWe present a new P‐wave seismic tomographic model for the region of the Paraná Basin and surroundings using a multiple‐frequency approach, providing better resolution than previous regional studies. We processed a total of 62,692 cross‐correlation delays for P, PKIKP, PcP, and PP phases distributed among 1,081 events using six different central frequencies (0.03, 0.06, 0.13, 0.25, 0.50, and 1 Hz). We merged our data with a previous multiple‐frequency study of the Amazonian Craton to cover regions outside of the study area, obtaining a total of 75,187 cross‐correlation delays. The data used are from the stations of the Brazilian Seismographic Network, and mainly from a temporary network (XC network) installed exclusively to study the region. The basement of the Paraná Basin is represented as a NE‐SW trending P‐wave high‐velocity anomaly, extending from the northern limit of the basin to the southwestern border of Brazil, consistent with previous reports. The limit between this block and the São Francisco Craton is characterized by decreased amplitude of the P‐wave high‐velocity anomaly. Synthetic tests show that a narrow boundary between these two blocks displays the same behavior. At the southeastern portion of this anomaly, decreasing amplitude is consistent with the limit of the Luiz Alves Craton, which was also corroborated by synthetic tests. The northern portion of the Rio Apa Block agrees with a previous tomographic model, confirming that it does not extend under the Pantanal Basin, however, in our model this structure does not extend as far south.

Pattern replication and extraction from spatial PPs in Molise Slavic

Abstract This paper investigates P-stranding under A′-extraction in spatial PPs in Molise Slavic (MSL). After showing that P-stranding bijectively correlates with dative case on the Ground argument of P, I argue that the cases of extraction at stake instantiate grammatical convergence in the form of “pattern replication” (Matras & Sakel 2007). A′-extraction is licensed by the presence of borrowed additional functional material valuing and interpreting K(ase). The richer structure allows for KP to move out of the PP Phase without violating Anti-Locality. Both Italian and MSL secondary Ps displaying P-stranding are characterized as instantiating one of two possible structural options for P-stranding. The alternative structure is argued to be instantiated in Germanic, consistently with existing proposals (Abels 2012). The choice between the two options, as well as the productivity of the selected option in a given grammatical system, is a matter of (micro-)variation in the availability of functional vocabulary.

Crystal polymorphism of 8OCB liquid crystal consisting of strongly polar rod-like molecules.

We report detailed experimental studies on the different crystal polymorphs of 8OCB (4′-octyloxy-4-cyanobiphenyl) obtained by cooling the sample from its melt. The 8OCB liquid crystal has a stable crystal phase which is known as commercial powder (CP) phase. In addition, it also exhibits various metastable crystal phases such as square-plate, needle phase and long parallelepiped (PP) phase. We identify the metastable crystal state often found on cooling the sample from its melt as PP phase which transforms to stable CP phase on aging at room temperature or by heating it above 312 K. Based on our experimental results, we find that the stable CP crystal phase of 8OCB is not a single homogeneous phase but is the coexistence of fibrillar nano-crystallites embedded in an amorphous phase. The heterogeneous nature of its stable crystal state is an intriguing feature of this pure compound consisting of relatively small rod-like molecules with a strong dipole moment along their long axis.