scholarly journals Nucleation of the β-polymorph in Composites of Poly(propylene) and Graphene Nanoplatelets

2019 ◽  
Vol 3 (2) ◽  
pp. 38 ◽  
Author(s):  
Valentina Guerra ◽  
Chaoying Wan ◽  
Tony McNally
Keyword(s):  
Graphene Nanoplatelets ◽  
Laboratory Scale ◽  
Degree Of Crystallinity ◽  
Mixing Efficiency ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Β Phase ◽  
A Value ◽  
Twin Screw ◽  
Poly Propylene

The effects of graphene nanoplatelets (GNPs) on the nucleation of the β-polymorph of polypropylene (PP) were studied when melt-mixed at loadings of 0.1–5 wt % using a laboratory scale twin-screw (conical) extruder and a twin-screw (parallel) extruder with L/D = 40. At low GNP loadings (i.e., ≤0.3 wt %), the mixing efficiency of the extruder used correlated with the β-nucleating activity of GNPs for PP. GNP agglomeration at low loadings (<0.5 wt %) resulted in an increase in the β-phase fraction (Kβ) of PP, as determined from X-ray diffraction measurements, up to 37% at 0.1 wt % GNPs for composites prepared using a laboratory scale twin-screw (conical) extruder. The level of GNP dispersion and distribution was better when the composites were prepared using a 16-mm twin-screw (parallel) extruder, giving a Kβ increase of 24% upon addition of 0.1 wt % GNPs to PP. For GNP loadings >0.5 wt %, the level of GNP dispersion in PP did not influence the growth of β-crystals, where Kβ reached a value of 24%, regardless of the type of extruder used. From differential scanning calorimetry (DSC) measurements, the addition of GNPs to PP increased the crystallization temperature (Tc) of PP by 14 °C and 10 °C for the laboratory scale extruder and 16-mm extruder, respectively, confirming the nucleation of PP by GNPs. The degree of crystallinity (Xc%) of PP increased slightly at low GNP additions (≤0.3 wt %), but then decreased with increasing GNP content.

scholarly journals Biobased Engineering Thermoplastics: Poly(butylene 2,5-furandicarboxylate) Blends

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 937 ◽  
Author(s):  
Niki Poulopoulou ◽  
George Kantoutsis ◽  
Dimitrios N. Bikiaris ◽  
Dimitris S. Achilias ◽  
Maria Kapnisti ◽  
...  
Keyword(s):  
Renewable Resources ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Reactive Blending ◽  
Scanning Calorimetry ◽  
Melt Polycondensation ◽  
Poly Ethylene Terephthalate ◽  
Furandicarboxylic Acid ◽  
Poly Ethylene ◽  
Poly Propylene

Poly(butylene 2,5-furandicarboxylate) (PBF) constitutes a new engineering polyester produced from renewable resources, as it is synthesized from 2,5-furandicarboxylic acid (2,5-FDCA) and 1,4-butanediol (1,4-BD), both formed from sugars coming from biomass. In this research, initially high-molecular-weight PBF was synthesized by applying the melt polycondensation method and using the dimethylester of FDCA as the monomer. Furthermore, five different series of PBF blends were prepared, namely poly(l-lactic acid)–poly(butylene 2,5-furandicarboxylate) (PLA–PBF), poly(ethylene terephthalate)–poly(butylene 2,5-furandicarboxylate) (PET–PBF), poly(propylene terephthalate)–poly(butylene 2,5-furandicarboxylate) (PPT–PBF), poly(butylene 2,6-naphthalenedicarboxylate)-poly(butylene 2,5-furandicarboxylate) (PBN–PBF), and polycarbonate–poly(butylene 2,5-furandicarboxylate) (PC–PBF), by dissolving the polyesters in a trifluoroacetic acid/chloroform mixture (1/4 v/v) followed by coprecipitation as a result of adding the solutions into excess of cold methanol. The wide-angle X-ray diffraction (WAXD) patterns of the as-prepared blends showed that mixtures of crystals of the blend components were formed, except for PC which did not crystallize. In general, a lower degree of crystallinity was observed at intermediate compositions. The differential scanning calorimetry (DSC) heating scans for the melt-quenched samples proved homogeneity in the case of PET–PBF blends. In the remaining cases, the blend components showed distinct Tgs. In PPT–PBF blends, there was a shift of the Tgs to intermediate values, showing some partial miscibility. Reactive blending proved to improve compatibility of the PBN–PBF blends.

Crystallization and Thermal Degradation of Green Nanocomposites Based on Lignin Coated Cellulose Nanocrystals and Poly(Lactic Acid)

2017 ◽  
Vol 737 ◽  
pp. 256-261 ◽  
Author(s):  
Martin Boruvka ◽  
Luboš Bĕhálek
Keyword(s):  
Lactic Acid ◽  
Cellulose Nanocrystals ◽  
Raw Material ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Crystalline Cellulose ◽  
Melt Crystallization ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Twin Screw

Cellulose is almost inexhaustible source of raw material comprising at least one-third of all biomass matter. Through deconstruction of cellulose hierarchical structure can be extracted highly crystalline cellulose nanocrystals (CNC) with impressive properties. However, the main barrier in the processing of the nanocomposites based on CNC is their inhomogeneous dispersion and distribution in the non-polar polymer matrix. In this paper is this problem addressed by use of novel hydrophobic lignin coated CNC as a biobased nucleation agents in poly (lactic acid) (PLA) nanocomposites. These green nanocomposites based on natural plant derived substances have enormous potential to replace materials originated from non-renewable resources and show promise of providing degradation back into the environment when they are no longer needed. Resulted composites prepared by twin screw extrusion and injection moulding were characterized by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of L-CNC (1, 2 and 3 wt. %) into PLA increased melt crystallization enthalpy and decreases the cold crystallization enthalpy. The degree of crystallinity (cc) increased from 5.6 % (virgin PLA) to 8.5 % (PLA/1-L-CNC), 10.3 % (PLA/2-L-CNC) and 10.7 % (PLA/3-L-CNC). The wide range of degradation temperatures of lignin coating has been observed starting at 100 °C.

A Spectroscopic and Thermodynamic Investigation of Mercuric Iodide Physically Confined in Porous Glass Hosts

1994 ◽  
Vol 366 ◽  
Author(s):  
D. O. Henderson ◽  
R. Mu ◽  
A. Ueda ◽  
A. Burger ◽  
K. T. Chen ◽  
...  
Keyword(s):  
Electronic Spectra ◽  
Energy Gap ◽  
Bulk Material ◽  
Mercuric Iodide ◽  
Thermodynamic Investigation ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Β Phase ◽  
Material Evidence ◽  
New Phase

ABSTRACTRaman and electronic spectra and results from differential scanning calorimetry (DSC) are reported for mercuric iodide (HgI2) confined in four different pore-sized glass hosts. The Raman spectra reveal peaks at 39 and 141 cm−1 that indicate the confined HgI2 is stabilized at 300 K in a modified orthorhombic (yellow) β-phase which is observed at 400 K for the bulk material. An additional band begins to appear at 145 cm−1 for pore radii smaller than 3.75 nm suggesting the presence of new phase of confined HgI2. The DSC measurements show the melting and freezing transitions of confined β-HgI2 are depressed from values reported for the bulk material and the depression increases as the pore size decreases. No transition is observed in the DSC measurement which could be attributed to the α→β transition for the confined material. Evidence supporting the new phase of HgI2 is observed in the electronic spectra of the confined HgI2 by the appearance of an energy gap transitions located at 2.7 eV.

scholarly journals Maleated polypropylene as coupling agent for polypropylene composites reinforced with Eucalyptus and Pinus particles

BioResources ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. 4774-4791
Keyword(s):  
Degree Of Crystallinity ◽  
Esterification Reaction ◽  
Scanning Electron Micrographs ◽  
Scanning Calorimetry ◽  
Polypropylene Composites ◽  
Maleated Polypropylene ◽  
The Matrix ◽  
Twin Screw ◽  
Coniferous Wood ◽  
Scanning Electron

Waste from the processing of hardwood and coniferous wood generated in the timber industries is difficult to dispose of and can cause considerable environmental impacts, such as soil and groundwater contamination. In this context, composites with varying concentrations of polypropylene, maleated polypropylene, and particulate Eucalyptus and Pinus waste were produced in a twin screw extruder and injection molded as test bodies for tensile and flexural tests. The morphology of the composites was investigated via scanning electron microscopy. The thermal properties were identified through differential scanning calorimetry. The tensile and flexural results for the two waste formulations indicated that the addition of vegetable fillers increased the modulus of elasticity and bending, and the compatibilizer provided increased resistance to stress and maximum deflection. The scanning electron micrographs illustrated the wetting of the cellulosic charge by the thermoplastic polymer with the compatibilizer, which corroborated the possible occurrence of an esterification reaction and hydrogen bonding interactions in the matrix-particle interface. The incorporation of waste in the composite resulted in the reduction of the degree of crystallinity of polypropylene, regardless of the use of the compatibilizer. This was explained by the barrier capacity of the charge, which prevented the growth of the crystals.

scholarly journals α- to β Transformation on PVDF Films Obtained by Uniaxial Stretch

2006 ◽  
Vol 514-516 ◽  
pp. 872-876 ◽  
Author(s):  
Vitor Sencadas ◽  
M. Vitor Moreira ◽  
Senentxu Lanceros-Méndez ◽  
António Sergio Pouzada ◽  
Rinaldo Gregório Filho
Keyword(s):  
Phase Transformation ◽  
Stretch Ratio ◽  
Polymer Chains ◽  
Degree Of Crystallinity ◽  
Phase Content ◽  
Scanning Calorimetry ◽  
Β Phase ◽  
Different Temperatures ◽  
Stretching Process ◽  
The Degree Of Crystallinity

The α to β phase transformation of PVDF through the stretching process at different temperatures was investigated. The optimum stretching conditions were studied and characterised by infrared spectroscopy and differential scanning calorimetry. The maximum β−phase content was achieved at 80°C and a stretch ratio of 5. Accompanying the phase transformation, a orientation of the polymer chains and a packing of the crystalline structure is observed. The stretch ratio does not significantly affect the degree of crystallinity.

scholarly journals Barrier Properties of GnP–PA-Extruded Films

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 669
Author(s):  
Regine Boldt ◽  
Andreas Leuteritz ◽  
Daniela Schob ◽  
Matthias Ziegenhorn ◽  
Udo Wagenknecht
Keyword(s):  
Filler Content ◽  
Barrier Properties ◽  
Permeation Rate ◽  
Graphene Nanoplatelets ◽  
Laboratory Scale ◽  
Morphological Properties ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Extruded Films ◽  
Different Temperatures

It is generally known that significant improvements in the properties of nanocomposites can be achieved with graphene types currently commercially available. However, so far this is only possible on a laboratory scale. Thus, the aim of this study was to transfer results from laboratory scale experiments to industrial processes. Therefore, nanocomposites based on polyamide (PA) and graphene nanoplatelets (GnP) were prepared in order to produce membranes with improved gas barrier properties, which are characterized by reduced permeation rates of helium. First, nanocomposites were prepared with different amounts of commercial availably graphene nanoplatelets using a semi-industrial-scale compounder. Subsequently, films were produced by compression molding at different temperatures, as well as by flat film extrusion. The extruded films were annealed at different temperatures and durations. In order to investigate the effect of thermal treatment on barrier properties in correlation to thermal, structural, and morphological properties, the films were characterized by differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS), optical microscopy (OM), transmission electron microscopy (TEM), melt rheology measurements, and permeation measurements. In addition to structural characterization, mechanical properties were investigated. The results demonstrate that the permeation rate is strongly influenced by the processing conditions and the filler content. If the filler content is increased, the permeation rate is reduced. The annealing process can further enhance this effect.

Effect of Silane Treated and Untreated Talc on the Properties of Thermoplastic Polyurethane/Polypropylene Blends

2013 ◽  
Vol 849 ◽  
pp. 121-126 ◽  
Author(s):  
Emi Govorčin Bajsić ◽  
Filipan Veljko ◽  
Vesna Ocelić Bulatović
Keyword(s):  
Storage Modulus ◽  
Thermoplastic Polyurethane ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Twin Screw ◽  
Mechanical Tensile ◽  
Polypropylene Blends ◽  
Pp Blends

The effect of the silane treated talc on the mechanical and thermal properties of talc filled thermoplastic polyurethane/polypropylene blends (TPU/PP blends) was investigated. Thermoplastic polyurethane and polypropylene are partially miscible due to the lack of interfacial interaction between the nonpolar crystalline PP and polar TPU. Blends of TPU and PP with silane treated and untreated-talc were prepared using melt blending in a laboratory twin-screw extruder. Organosilane (3-glycidoxypropyl-trimetoxy silane coupling agent) was used to treat talc in order to improve the affinity between the filler and the TPU/PP blends. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and mechanical (tensile test) measurements were used to characterize the talc filled and silane treated talc filled composites and TPU/PP/talc blends. The addition of silane treated and untreated talc in TPU/PP blends improved miscibility in all investigated TPU/PP/talc blends. The silane treatment increases the storage modulus in all investigated TPU/PP/talc blends in comparison with that of the untreated TPU/PP/talc blends. The obtained DSC results show that the addition of silane treated talc increases the degree of crystallinity (χc) of TPU/PP/talc blends because of the improved adhesion between the polymer and the treated talc. Addition of silane treated talc improved the mechanical properties as compared to TPU/PP/talc blends without chemical modification of talc. The results of strength correlate to the values of the storage modulus and crystallinity of the investigated TPU/PP/talc blends.

INVESTIGATION ON THE MORPHOLOGICAL AND THERMAL PROPERTIES OF POLYLACTIC ACID/POLYCAPROLACTONE LOADED WITH HALLOYSITE NANOTUBES AND BASALT FIBER

2022 ◽  
Author(s):  
A. ARUL JEYA KUMAR ◽  
NIRANJAN S. RAJ ◽  
C. SAIPRASAD ◽  
AGHALAYAM R. SUDHANVA
Keyword(s):  
Thermal Properties ◽  
Polylactic Acid ◽  
Basalt Fiber ◽  
Halloysite Nanotubes ◽  
Morphological Characterization ◽  
Degree Of Crystallinity ◽  
Thermal Testing ◽  
Scanning Calorimetry ◽  
The Matrix ◽  
Twin Screw

This paper is focused on the analysis of the morphological and thermal properties of the biomedical composites, polylactic acid (PLA) and polycaprolactone (PCL) matrix, reinforced with basalt fibers (BFs) and using halloysite nanotubes (HNT) as filler material. Four different composites, viz. PPHB 1, PPHB 2, PPHB 3 and PPHB 4, are obtained by varying the weight fractions of these materials using twin-screw extrusion followed by injection molding. The morphological characterization is performed on these composites using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. SEM reveals homogenous and strong bonding between the matrix, reinforcement and filler. The BF are well embedded in the matrix with a random orientation. No formation of voids and cracks is observed. The functional groups present and the types of vibration experienced by the chemical bonds were observed in the FTIR spectra. The composites are subjected to thermal testing such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The PPHB 2, which contains 80% PLA, 10% BF, 7% PCL and 3% HNT, has the highest degree of crystallinity, as revealed by DSC, and exhibits the most optimum thermal degradation characteristics as indicated by TGA.

Mechanical and thermal characterization of grafted PP-NCC nanocomposites

2019 ◽  
pp. 089270571987822
Author(s):  
Saud Aldajah ◽  
Mohammad Y Al-Haik ◽  
Waseem Siddique ◽  
Mohammad M Kabir ◽  
Yousef Haik
Keyword(s):  
Thermal Properties ◽  
Interfacial Adhesion ◽  
Thermal Characterization ◽  
Mechanical And Thermal Properties ◽  
Screw Extruder ◽  
Scanning Calorimetry ◽  
Three Point Bending ◽  
Twin Screw ◽  
Thermal Stability Of

This study reveals the enhancement of mechanical and thermal properties of maleic anhydride-grafted polypropylene (PP- g-MA) with the addition of nanocrystalline cellulose (NCC). A nanocomposite was manufactured by blending various percentages of PP, MA, and NCC nanoparticles by means of a twin-screw extruder. The influence of varying the percentages of NCC on the mechanical and thermal behavior of the nanocomposite was studied by performing three-point bending, nanoindentation, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy tests. The novelty of this study stems on the NCC nanoparticles and their ability to enhance the mechanical and thermal properties of PP. Three-point bending and nanoindentation tests revealed improvement in the mechanical properties in terms of strength, modulus, and hardness of the PP- g-MA nanocomposites as the addition of NCC increased. SEM showed homogeneity between the mixtures which proved the presence of interfacial adhesion between the PP- g-MA incorporated with NCC nanoparticles that was confirmed by the FTIR results. DSC and TGA measurements showed that the thermal stability of the nanocomposites was not compromised due to the addition of the coupling agent and reinforced nanoparticles.

scholarly journals PEG-POSS Star Molecules Blended in Polyurethane with Flexible Hard Segments: Morphology and Dynamics

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 99
Author(s):  
Konstantinos N. Raftopoulos ◽  
Edyta Hebda ◽  
Anna Grzybowska ◽  
Panagiotis A. Klonos ◽  
Apostolos Kyritsis ◽  
...  
Keyword(s):  
Glass Transition ◽  
Star Polymer ◽  
Polymerization Process ◽  
Degree Of Crystallinity ◽  
Dielectric Relaxation Spectroscopy ◽  
Scanning Calorimetry ◽  
Similar System ◽  
Soft Phase ◽  
Hard Segments ◽  
Star Molecules

A star polymer with a polyhedral oligomeric silsesquioxanne (POSS) core and poly(ethylene glycol) (PEG) vertex groups is incorporated in a polyurethane with flexible hard segments in-situ during the polymerization process. The blends are studied in terms of morphology, molecular dynamics, and charge mobility. The methods utilized for this purpose are scanning electron and atomic force microscopies (SEM, AFM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and to a larger extent dielectric relaxation spectroscopy (DRS). It is found that POSS reduces the degree of crystallinity of the hard segments. Contrary to what was observed in a similar system with POSS pendent along the main chain, soft phase calorimetric glass transition temperature drops as a result of plasticization, and homogenization of the soft phase by the star molecules. The dynamic glass transition though, remains practically unaffected, and a hypothesis is formed to resolve the discrepancy, based on the assumption of different thermal and dielectric responses of slow and fast modes of the system. A relaxation α′, slower than the bulky segmental α and common in polyurethanes, appears here too. A detailed analysis of dielectric spectra provides some evidence that this relaxation has cooperative character. An additional relaxation g, which is not commonly observed, accompanies the Maxwell Wagner Sillars interfacial polarization process, and has dynamics similar to it. POSS is found to introduce conductivity and possibly alter its mechanism. The study points out that different architectures of incorporation of POSS in polyurethane affect its physical properties by different mechanisms.

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