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.

Performance of Polypropylene Composites Filled by Calcium Carbonate Whiskers

2011 ◽  
Vol 399-401 ◽  
pp. 415-418
Author(s):  
Qiu Ju Sun ◽  
Gui Zhen Zhao ◽  
Shi Gang Xin ◽  
Shi Wei Wu ◽  
Jie Lu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Calcium Carbonate ◽  
Sodium Stearate ◽  
X Ray Diffraction ◽  
Screw Extruder ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Polypropylene Composites ◽  
Twin Screw ◽  
Scanning Electron

Calcium carbonate (CaCO3) whiskers were firstly treated by sodium stearate, and then blended with polypropylene (PP) to prepare the composites by a closely intermeshing co-rotating twin-screw extruder at 200°C. The performance of the composites, such as thermal behavior, microstructure and mechanical properties, were analyzed with differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical testing. The results showed that CaCO3 whisker influenced the crystalline behavior of PP phase in the blends because of its intervening. Moreover, thermo-decomposing temperature, tensile and bending strengths of the blends all increased with increasing whisker content. CaCO3 whiskers had good reinforcing and toughening effects on PP.

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.

Effect of different extrusion methods on physicochemical properties and qualities of noodles based on rice flour

2021 ◽  
pp. 108201322110692
Author(s):  
Nispa Seetapan ◽  
Bootsrapa Leelawat ◽  
Nattawut Limparyoon ◽  
Rattana Yooberg
Keyword(s):  
Moisture Content ◽  
Rice Flour ◽  
Extrusion Process ◽  
Scanning Electron Micrographs ◽  
Twin Screw Extruder ◽  
Capillary Rheometer ◽  
Screw Extruder ◽  
Scanning Calorimetry ◽  
Twin Screw ◽  
Thermomechanical Processes

Rice noodles have been manufactured in the food industry using different extrusion methods, such as traditional and modern extrusions, which affect the noodle structure and qualities. Therefore, the effects of the extrusion process on qualities of rice noodles using the same blend of rice flour and crosslinked starch were evaluated. In this study, a capillary rheometer was used as an alternative approach to simulate the traditional extrusion method in which the noodles are obtained by continuously pressing the pregelatinized noodle dough through a die. For modern extrusion, a twin-screw extruder was employed to obtain the noodles in a one-step process. The optimal range of moisture content used in the formulation was studied. Upon cooking, the noodles showed a decrease in cooking time and cooking loss with increasing moisture content in the formulation. All cooked noodles showed comparable tensile strength, but those extruded by a twin-screw extruder had substantially greater elongation. Scanning electron micrographs revealed that the noodles prepared using the extruder had a denser starch matrix, while those obtained from a capillary rheometer showed the aggregation of starch fragments relevant to the existence of starch gelatinization endotherm from differential scanning calorimetry. This indicated that the extrusion process using the twin-screw extruder provided a more uniform starch transformation, i.e., more starch granule disruption and gelatinization, thus giving the noodles a more coherent structure and better extensibility after cooking. The obtained results suggested that different thermomechanical processes used in the noodle industry gave the extruded rice noodles different qualities respective to their different microstructures.

Thermal and Tensile Properties of PP Nanocomposite Blends

2008 ◽  
Vol 47-50 ◽  
pp. 21-24
Author(s):  
C. Rosales ◽  
V. Contreras ◽  
M. Matos ◽  
R. Perera ◽  
N. Villarreal ◽  
...  
Keyword(s):  
Tensile Modulus ◽  
Polyamide 6 ◽  
Dispersed Phase ◽  
Scanning Calorimetry ◽  
Binary Blend ◽  
Polyethylene Blends ◽  
Metallocene Polyethylene ◽  
The Matrix ◽  
Twin Screw ◽  
Layered Clay

Polypropylene/polyamide-6 and polypropylene/metallocene polyethylene blends containing 2.5 phr of organophilic modified montmorillonite were prepared in a twin-screw extruder followed by injection molding. In order to compare, blends without layered clay were also made. Styreneethylene- butylene-styrene copolymer and polypropylene grafted with anhydride maleic were used as compatibilizers in the ternary blends and in the PP nanocomposite preparation, respectively. The presence of tactoids, intercalated and exfoliated structures was observed by TEM in some of the samples containing layered clay and modified PP materials. Results showed that the compatibilized blends prepared without clay are tougher than those prepared with the nanocomposite of PP as the matrix phase and no significant changes in tensile moduli were observed between them. However, the binary blend with a nanocomposite of PP as matrix and metallocene polyethylene exhibited better tensile toughness and lower tensile modulus, than those prepared with a nanocomposite of PP and polyamide-6 as dispersed phase. These results are related to the degree of clay dispersion in the PP and to the type of morphology developed in the different blends. Differential scanning calorimetry (DSC) showed that blends with a finer and homogeneously dispersed morphology determined by SEM, the PA component exhibited fractionated crystallization exotherms in the temperature range of 159-185°C. Also, nucleation of the PP component by PA phase and/or the layered clay was observed in the blends with PA as dispersed phase.

INNOVATIVE MANUFACTURING OF CARBON NANOTUBE-LOADED FIBRILLAR POLYMER COMPOSITES

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2459-2465 ◽  
Author(s):  
R. J. T. LIN ◽  
D. BHATTACHARYYA ◽  
S. FAKIROV
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Polymer Composites ◽  
Polyamide 66 ◽  
Screw Extruder ◽  
Enhancing Effect ◽  
The Matrix ◽  
Twin Screw ◽  
New Type ◽  
Scanning Electron

The concept of microfibrillar composite (MFC) has been used to create a new type of polymer composites, in which the reinforcing microfibrils are loaded with carbon nanotubes (CNT). Polyamide 66 (PA66) has been melt blended with polypropylene in a twin screw extruder with and without CNT, and thereafter cold drawn to create a fibrillar state as well as to align the CNT in the PA66 microfibrils. The drawn bristles were compression moulded at 180°C to prepare MFC plates. The scanning electron microscope (SEM) observations indicate near perfect distribution of CNT in the reinforcing PA66 microfibrils. Although the fibrillated PA66 is able to improve the tensile stiffness and strength as expected from the MFC structure, the incorporation of CNT does not exhibit any further enhancing effect. It rather adversely affects the mechanical properties due to poor interface adhesion between the matrix and the reinforcing microfibrils with the presence of CNT, as demonstrated by SEM. However, the resulting highly aligned CNT within the MFC are expected to affect the physical and functional properties of these composites.

scholarly journals Polyamide 6/Poly(vinylidene fluoride) Blend-Based Nanocomposites with Enhanced Rigidity: Selective Localization of Carbon Nanotube and Organoclay

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 184 ◽  
Author(s):  
Hung-Ming Lin ◽  
Kartik Behera ◽  
Mithilesh Yadav ◽  
Fang-Chyou Chiu
Keyword(s):  
Carbon Nanotube ◽  
Vinylidene Fluoride ◽  
Domain Size ◽  
Polyamide 6 ◽  
Vital Role ◽  
Scanning Electron Micrographs ◽  
Scanning Calorimetry ◽  
Poly Vinylidene Fluoride ◽  
Twin Screw ◽  
Diffraction Patterns

Polyamide 6 (PA6)/poly(vinylidene fluoride) (PVDF) blend-based nanocomposites were successfully prepared using a twin screw extruder. Carbon nanotube (CNT) and organo-montmorillonite (30B) were used individually and simultaneously as reinforcing nanofillers for the immiscible PA6/PVDF blend. Scanning electron micrographs showed that adding 30B reduced the dispersed domain size of PVDF in the blend, and CNT played a vital role in the formation of a quasi-co-continuous PA6-PVDF morphology. Transmission electron microscopy observation revealed that both fillers were mainly located in the PA6 matrix phase. X-ray diffraction patterns showed that the presence of 30B facilitated the formation of γ-form PA6 crystals in the composites. Differential scanning calorimetry results indicated that the crystallization temperature of PA6 increased after adding CNT into the blend. The inclusion of 30B retarded PA6 nucleation (γ-form crystals growth) upon crystallization. The Young’s and flexural moduli of the blend increased after adding CNT and/or 30B. 30B exhibited higher enhancing efficiency compared with CNT. The composite with 2 phr 30B exhibited 21% higher Young’s modulus than the blend. Measurements of the rheological properties confirmed the development of a pseudo-network structure in the CNT-loaded composites. Double percolation morphology in the PA6/PVDF blend was achieved with the addition of CNT.

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.

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 Isothermal Crystallization Kinetics and Morphology of Double Crystalline PCL/PBS Blends Mixed with a Polycarbonate/MWCNTs Masterbatch

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 682 ◽  
Author(s):  
Thandi P. Gumede ◽  
Adriaan S. Luyt ◽  
Agnieszka Tercjak ◽  
Alejandro J. Müller
Keyword(s):  
Isothermal Crystallization ◽  
Scanning Calorimetry ◽  
Multiwalled Carbon ◽  
Intimate Contact ◽  
Rich Phase ◽  
Force Microscopy ◽  
Partial Miscibility ◽  
Nucleation Effect ◽  
The Matrix ◽  
Twin Screw

In this work, the 70/30 and 30/70 w/w polycaprolactone (PCL)/polybutylene succinate (PBS) blends and their corresponding PCL/PBS/(polycarbonate (PC)/multiwalled carbon nanotubes (MWCNTs) masterbatch) nanocomposites were prepared in a twin-screw extruder. The nanocomposites contained 1.0 and 4.0 wt% MWCNTs. The blends showed a sea-island morphology typical of immiscible blends. For the nanocomposites, three phases were formed: (i) The matrix (either PCL- or PBS-rich phase depending on the composition), (ii) dispersed polymer droplets of small size (either PCL- or PBS-rich phase depending on the composition), and (iii) dispersed aggregates of tens of micron sizes identified as PC/MWCNTs masterbatch. Atomic force microscopy (AFM) results showed that although most MWCNTs were located in the PC dispersed phase, some of them migrated to the polymer matrix. This is due to the partial miscibility and intimate contact at the interfaces between blend components. Non-isothermal differential scanning calorimetry (DSC) scans for the PCL/PBS blends showed an increase in the crystallization temperature (Tc) of the PCL-rich phase indicating a nucleation effect caused by the PBS-rich phase. For the nanocomposites, there was a decrease in Tc values. This was attributed to a competition between two effects: (1) The partial miscibility of the PC-rich and the PCL-rich and PBS-rich phases, and (2) the nucleation effect of the MWCNTs. The decrease in Tc values indicated that miscibility was the dominating effect. Isothermal crystallization results showed that the nanocomposites crystallized slower than the neat blends and the homopolymers. The introduction of the masterbatch generally increased the thermal conductivity of the blend nanocomposites and affected the mechanical properties.

Influence of Bridge Fires on the Properties of Concrete and Steel Components

2021 ◽  
pp. 036119812110363
Author(s):  
Dan Huang ◽  
Tom Bradt ◽  
Tseng Tzu-Chun ◽  
Sijia Wang ◽  
Jan Olek ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Highway Bridges ◽  
Fire Exposure ◽  
Scanning Calorimetry ◽  
The Matrix ◽  
Degree Of Degradation ◽  
Detection And Quantification ◽  
Scanning Electron

Concrete and steel specimens were collected from control (unexposed) and fire-exposed sections of highway bridges in the state of Indiana, U.S., to evaluate the degree of degradation of selected properties of concrete and steel components. The changes in the properties of concrete were evaluated using differential scanning calorimetry (DSC) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) techniques. The focus of concrete evaluation was on detection and quantification of calcium hydroxide (CH), identification of changes in the quality and quantity of other hydrates, assessment of the extent of cracking in the matrix, and the occurrence of debonding of aggregates. Concrete collected from the sections of bridges exposed to fire was found to contain lower amounts of CH compared with the concrete from the control (i.e., not exposed) sections. The observed degree of cracking and aggregate debonding was also higher in specimens exposed to fire. Steel specimens were evaluated with respect to changes in the microstructure (the size and the pattern of the grains) and hardness. No significant changes resulting from fire exposure were detected.

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