scholarly journals Role of Wood Fibers in Tuning Dynamic Rheology, Non-Isothermal Crystallization, and Microcellular Structure of Polypropylene Foams

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 106 ◽  
Author(s):  
Yongming Song ◽  
Youyong Wang ◽  
Hao Li ◽  
Qiling Zong ◽  
Ailing Xu
Keyword(s):  
Isothermal Crystallization ◽  
Fiber Composite ◽  
Cell Structure ◽  
Wood Fiber ◽  
Crystallization Rate ◽  
Complex Viscosity ◽  
Expansion Ratio ◽  
Wood Fibers ◽  
Cell Nucleation ◽  
Composite Foams

Microcellular polypropylene (PP)/wood fiber composite foams were fabricated via batch foaming assisted by supercritical CO2 (scCO2). Effects of wood fibers on rheology, crystallization, and foaming behaviors of PP were comprehensively investigated. The obtained results showed that the incorporation of wood fibers increased the complex viscosity and the storage modulus of the PP matrix. Jeziorny’s model for non-isothermal crystallization kinetics indicated that wood fibers did not change the crystal growth. However, the crystallization rate of the PP matrix was decreased to a certain extent with increasing wood fiber loadings. The wood fiber exerts a noticeable role in improving the cell density and reducing the cell size, despite decreasing the expansion ratio. Interestingly, a “small-sized cells to large-sized cells” gradient cell structure was found around the wood fibers, implying cell nucleation was induced at the interface between wood fiber and PP matrix. When wood fiber loadings were specifically increased, a desirable microcellular structure was obtained. However, further increasing the wood fiber loadings deteriorated the cell structure. Moreover, the crystallinity of the composite foams initially decreased and then slightly increased with increasing wood fiber loadings, while the crystal size decreased.

A Novel Design for Producing Fine-Celled Foams of Plastic/Wood-Fiber Composites

2000 ◽  
Author(s):  
Ghaus M. Rizvi ◽  
Chul B. Park
Keyword(s):  
System Design ◽  
Cell Morphology ◽  
Fiber Composite ◽  
Wood Fiber ◽  
Fiber Composites ◽  
Wood Fibers ◽  
Blowing Agent ◽  
Composite Foams ◽  
Innovative System ◽  
Novel Design

Abstract This paper presents an innovative system design for production of plastic/wood-fiber composite foams based on a chemical blowing agent (CBA). Wood-fiber inherently contains moisture, which adversely affects the foam processing and the resultant cell morphology. To improve the cell morphology, the moisture content in the final foam should be minimized. A novel system design is presented for achieving this goal. Undried wood-fibers were processed together with HDPE, CBA and a coupling agent (CA) in a tandem extrusion system. At the interconnection of the two extruders, a vent was provided to purge the moisture into the atmosphere. HDPE/wood-fiber composite foams were produced on this system and on a single extruder without the vent, for comparison. The cellular morphology and volume expansion ratios of the foamed composites were characterized. The foams produced on the newly developed tandem system exhibited significantly improved cell morphology and surface quality.

Friction and Wear Behavior of POM Composites Filled with LDPE and Wood Fibers

2011 ◽  
Vol 415-417 ◽  
pp. 293-296 ◽  
Author(s):  
Xiao Han Xiang ◽  
Ding Han Xiang ◽  
Wei Fang ◽  
Jiao Ling Ma
Keyword(s):  
Friction And Wear ◽  
Wear Behavior ◽  
Fiber Composite ◽  
Low Cost ◽  
Wood Fiber ◽  
Wood Fibers ◽  
Wear Process ◽  
Ldpe Composites ◽  
Wear Tests ◽  
Friction And Wear Tests

Polyoxymethylene (POM) composites filled with low-density polyethylene (LDPE) and wood fibers were prepared by injection-molding. Friction and wear tests were carried out in a reciprocating sliding tribotester. Results showed that 5wt.%LDPE acted effectively as the internal lubricant for POM. Further addition of the wood fiber increased the wear rate of the POM/LDPE composites but had little effect on the coefficient of coefficient in the presence of LDPE. SEM observations showed that the main wear mechanism for unfilled POM was adhesive wear, while in the case of POM composites abrasion and fatigue seemed to govern the wear process. It was suggested that, the POM/LDPE/Wood fiber composite, which is low-cost and environmentally friendly, has the potential for tribological applications.

Foaming behavior of microcellular poly(lactic acid)/TPU composites in supercritical CO2

2017 ◽  
Vol 31 (1) ◽  
pp. 61-78 ◽  
Author(s):  
Daifang Xu ◽  
Kejing Yu ◽  
Kun Qian ◽  
Chul B Park
Keyword(s):  
Lactic Acid ◽  
Cell Structure ◽  
Thermoplastic Polyurethane ◽  
Optical Microscope ◽  
Expansion Ratio ◽  
Poly Lactic Acid ◽  
Free Energy Barrier ◽  
Scanning Calorimetry ◽  
Melt Strength ◽  
Cell Nucleation

This article presents the effects of thermoplastic polyurethane (TPU) on the crystallization and melt strength of poly(lactic acid) (PLA) and on the enhancement of cell nucleation and expansion ratio to manufacture microcellular thermoplastic PLA foams in supercritical carbon dioxide. Addition of TPU increased the crystallinity and decreased the crystallite size as observed by differential scanning calorimetry and polarized optical microscope. The formed crystal domains worked as cross-linking points to increase the melt strength of a polymer that potentially affected the cell growth. Scanning electron microscope confirmed the immiscibility between PLA and TPU, and TPU was dispersed as islands in the PLA matrix. This phase morphology further influenced the cell structure of the PLA/TPU foams. TPU acted as a nucleating agent to enhance heterogeneous cell nucleation that is caused by the decrease in free energy barrier. Tensile stress that generated around the TPU and in some local regions surrounding the crystals and crystallization was dominant to induce cell nucleation.

Microcellular morphology evolution of polystyrene/thermoplastic polyurethane blends in the presence of supercritical CO2

2019 ◽  
Vol 38 (3-4) ◽  
pp. 68-85 ◽  
Author(s):  
Zhongjie Qu ◽  
Jianguo Mi ◽  
Yang Jiao ◽  
Hongfu Zhou ◽  
Xiangdong Wang
Keyword(s):  
Cell Structure ◽  
Thermoplastic Polyurethane ◽  
Complex Viscosity ◽  
Morphology Evolution ◽  
Melt Blending ◽  
Insulation Property ◽  
Interesting Phenomenon ◽  
Cell Nucleation ◽  
Thermal Insulation Property ◽  
And Storage

In this article, a facile melt blending and solid batch foaming approach was proposed to prepare microcellular polystyrene/thermoplastic polyurethane (PS/TPU) blending foams with supercritical carbon dioxide (CO2). Compared with those of pure PS and pure TPU, an interesting phenomenon about the enhanced complex viscosity and storage modulus, as well as decreased loss factor of PS/TPU blends, was found. The solubility of CO2 in the PS/TPU blends was enhanced, owing to the CO2 solubilization effects of TPU. An interesting bimodal cell structure (BCS) was observed in the PS/TPU blending foams with the TPU content of 10, 15, and 20%. Consequently, a significant conclusion could be speculated that the generation of BCS in the PS/TPU blending system depended on not only the viscosity and morphology of the polymer blends but also the solubility and diffusivity of the CO2 as well as the type of cell nucleation. The thermal insulation property of PS foam was improved by the introduction of TPU.

Aluminum and copper deposition through the process of thermal flame spray on polypropylene-pine wood fiber composite filaments and their applications

2021 ◽  
pp. 002199832110365
Author(s):  
Sônia MA Veroneze ◽  
Thais HS Flores-Sahagun ◽  
Ramón SC Paredes ◽  
Kestur Gundappa Satyanarayana
Keyword(s):  
Fiber Composite ◽  
Wood Fiber ◽  
Physical And Mechanical Properties ◽  
Heat Treating ◽  
Flame Spray ◽  
Pine Wood ◽  
Thermal Spray Process ◽  
Spray Process ◽  
Copper Coatings ◽  
Study Results

This paper presents a study about polypropylene-pine wood composites, both as filaments and products, coated with aluminum (Al) or copper (Cu), obtained through flame thermal spray process after subjecting the composites to thermal treatments in the second and third step of the study. Results revealed that a previous aluminum layer was needed in order to obtain copper coatings on the composites. The physical and mechanical properties of both metal coated composite filaments were also evaluated and compared with the uncoated composite filaments with and without heat treating these. Consequently, it was observed that the nature of the coating adhesion on the substrates was mechanical, and therefore abrasion blasting of filaments or the use of a higher wood fiber content in the composite improved the Al or Cu adhesion. Also, it was observed that extruded wood fiber/PP filaments should not be cooled in water because pieces might be molded directly once the moisture affects the metal coatings adhesion onto the substrates.

LDPE/MWCNT and LDPE/MWCNT/UHMWPE self-reinforced fiber-composite foams prepared via supercritical CO2: a microstructure-engineering property perspective

2021 ◽  
pp. 105248
Author(s):  
Mohammad Aghvami-Panah ◽  
Mahyar Panahi-Sarmad ◽  
Amir Abbas Seraji ◽  
Seifollah Jamalpour ◽  
Seyed Reza Ghaffarian ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Fiber Composite ◽  
Engineering Property ◽  
Composite Foams ◽  
Reinforced Fiber

scholarly journals Morphological, thermal, and thermomechanical properties of cellulose nanocrystals reinforced polylactide/poly [(butylene succinate)-co-adipate] blend composite foams

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Mpho Phillip Motloung ◽  
Simphiwe Zungu ◽  
Vincent Ojijo ◽  
Jayita Bandyopadhyay ◽  
Suprakas Sinha Ray
Keyword(s):  
Morphological Analysis ◽  
Cell Structure ◽  
Environmentally Friendly ◽  
Processing Technique ◽  
Thermomechanical Properties ◽  
Environmental Concerns ◽  
Butylene Succinate ◽  
Peak Intensity ◽  
Composite Foams ◽  
Reinforcing Agent

Abstract This study examines the influence of cellulose nanocrystal (CN) particles on the morphological, thermal, and thermo-mechanical properties of polylactide (PLA)/poly [(butylene succinate)-co-adipate] (PBSA) blend foams prepared by casting and particulate leaching method using fructose as porogen particles. The morphological analysis showed an interconnected open-cell structure, with porosity above 80%. The crystallinity of the prepared foams was disrupted by the inclusion of CN particles as observed from XRD analyses, which showed a decrease in PLA crystal peak intensity. With regards to neat blend foam, the onset thermal degradation increased with the addition of CN particles, which also increased the thermal stability at 50% weight loss. Furthermore, CN acted as a reinforcing agent in improving the stiffness of the prepared blend foam. Overall, completely environmentally friendly foams were successfully prepared, as a potential material that can replace the current existing foam materials that pose many environmental concerns. However, there is a need to develop an environmentally friendly processing technique.

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