Mechanical, Morphological and Thermal Properties of Pine Needle-Reinforced Polymer Composites (original) (raw)
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Polymer Engineering and Science, 2007
Dynamically vulcanized blends of polyoxymethylene (POM) and ethylene propylene diene terpolymer (EPDM) with and without compatibilizer were prepared by melt mixing in a twin screw extruder. Maleic anhydride (MAH) grafted EPDM (EPDM-g-MAH) has been used as a compatibilizer. Dicumyl peroxide was used for vulcanizing the elastomer phase in the blends. Mechanical, dynamical mechanical, thermal, and morphological properties of the blend systems have been investigated as a function of blend composition and compatibilizer content. The impact strength of both dynamically vulcanized blends and compatibilized/dynamically vulcanized blends increases with increase in elastomer content with decrease in tensile strength. Dynamic mechanical analysis shows decrease in tanδ values as the elastomer and compatibilizer content increased. Thermograms obtained from differential scanning calorimetric studies reveal that compatibilized blends have lower Tm values compared to dynamically vulcanized blends, which confirms strong interaction between the plastic and elastomer phase. Scanning electron microscopic observations on impact fractured surface indicate reduction in particle size of elastomer phase and its high level of dispersion in the POM matrix. In the case of compatibilized blends high degree of interaction between the component polymers has been observed. POLYM. ENG. SCI., 47:934–942, 2007. © 2007 Society of Plastics Engineers
Journal of Applied Polymer Science, 2005
High-performance thermoplastic elastomers (TPEs), based on recycled high-density polyethylene (HDPER), olefinic type ethylene–propylene–diene monomer rubber (EPDM), and ground tire rubber (GTR) treated with bitumen, were prepared by using dynamic vulcanization technology, and their structure–property relationships were investigated. It was established that special pretreatment of GTR by bitumen confers outstanding mechanical properties on the resulting TPEs. TPEs, containing GTR pretreated by bitumen, exhibit thermal behavior similar to that of the HDPER/EPDM basic blend in the temperature region up to about 340°C. Rheological measurements showed that bitumen acts as an effective plasticizer for the GTR-containing TPEs. SEM, DSC, and DMTA results revealed improved adhesion between the particles of GTR treated by bitumen and the surrounding thermoplastic matrix, compared to that of the untreated GTR particles. It was concluded that bitumen acts as an effective devulcanizing agent in the GTR treatment stage. In the following steps of TPE production, bitumen acts simultaneously as a curing agent for the rubber components (EPDM/GTR) and as a compatibilizer for the blend components. GTR-containing TPEs, prepared by extrusion technology, were reprocessed (by passing through the extruder six times) without any observable changes in their tensile properties, thermal stability, and melt viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 659–671, 2005
NONLINEAR …, 2004
Structure-property relationships for different recycled polyolefins/rubbers reactively compatibilized or plasticized thermoplastic elastomers (TPEs) produced by using dynamic vulcanization technology have been studied. The wide-angle X-ray scattering (WAXS), dynamic mechanical thermal analysis (DMTA) and mechanical testing have been used for analysis of samples prepared. For one test series the TPEs have been produced on the base on recycled low-or high-density polyethylenes (LDPE R , HDPE R ) and two fresh rubbers: butadiene rubber (BR) and butadiene-methylstyrene rubber (SBR) as well as compatibilized with several reactive couples (reactive polyethylene /reactive rubber). In the other test series the LDPE R /BR and HDPE R /SBR TPEs containing reclaimed (partially devulcanized) ground tyre rubber (GTR R ) were compatibilized by the same systems and their properties and phase structure have been investigated. In third test series the LDPE R (HDPE R )/EPDM (ethylene-propylenediene monomer) rubber TPEs containing GTR or GTR plasticized with bitumen were produced and studied. For compatibilized TPEs the increasing components compatibility due to the growth of interfacial adhesion and formation of an essential interface layer consisted of all components have been observed. The highest improvement of tensile properties has been observed for LDPE R (HDPE R )/EPDM/(GTR/bitumen) TPEs in comparison to other series or bitumen-free TPEs. The values of TS and EB increase respectively by 23-67 % and 93-95 % for LDPE R /EPDM/(GTR/bitumen) TPEs, and 74-10 2% and 570-736 % for HDPE R /EPDM/(GTR/bitumen) TPEs.
Polym Eng Sci, 2009
The effects of different fillers on physical, mechanical, and optical properties of styrenic-based thermoplastic elastomers were investigated by experimental study. Poly[styrene-b-(ethylene-co-butylene)-b-styrene] block copolymer (SEBS)-based thermoplastic elastomer composites were prepared in a co-rotating intermeshing twin-screw extruder, using silica and calcite as filler materials with three different particle sizes. The loading ratios in the composites were varied. Hardness, density, tensile strength, tear strength, compression set, wear resistance, transmittance, and haze measurements were performed. Thermal properties and morphological structure were investigated by differential scanning calorimeter (DSC) and scanning electron microscopy (SEM), respectively. The results show that, an interaction between silica and the polymer matrix exists, whereas calcite does not show any interaction with the polymer. Therefore, it is concluded that, calcium carbonate can be used in the composite as filler for cost efficiency, whereas silica can be used as reinforcing material in SEBS-based thermoplastic elastomer composites, when optical properties are also concerned.
Polymer …, 2004
Recycled low density polyethylene (R-LDPE) has been reactively compatibilized with butadiene rubber (BR) by using small additions of reactive polyethylene copolymers and reactive BRs to produce thermoplastic elastomers (TPEs). TPEs were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), rheology measurements, wide-angle X-ray scattering (WAXS) and mechanical testing. WAXS results show that the presence of BR and reactive modifiers does not completely prevent the crystallization of R-LDPE during the TPE formation. Depression of the melting point has been found in all cases. Also in all cases, compatibility is provided by formation of interfacial layers. The best mechanical characteristics are obtained for R-LDPE + BR blends compatibilized with poly(ethylene-co-acrylic acid) (PE-co-AA) and polybutadiene terminated with isocyanate groups (PB-NCO) for PB-NCO = 7.5 wt% per PB and COOH/NCO ratio = 1/1. The stress at break and elongation at break are respectively improved by 31 % and 63 %. The PB-NCO modifier participates in co-vulcanization with BR in the rubber phase and reacts at the interface with the PE-co-AA dissolved in the polyolefin phase. As a result, the amorphous phase of R-LDPE is dissolved by the rubber phase and a morphology with dual phase continuity is formed, assuring an improvement of mechanical properties of TPEs.
British Polymer Journal, 1978
The melting and crystallisation behaviour of crystalline phases in poly (hexamethylene terephthalate)/poly(oxytetramethylene) block copolymers have been investigated in relation to copolymer composition and polyether block molecular weight (m.w.). In contrast to that in corresponding homopolymer blends, the polyester crystallinity in the block polymers is greatly reduced by incorporation of polyether units, though some persists even at low polyester contents. Concomitant changes in the glass transition temperatures show part of the polyester component to form a homogeneous component of the amorphous phase. The mechanical properties change with composition in parallel with the changes in copolymer crystallinity and Tg. Copolymers with 20-60 w % of poly(oxytetramethy1ene) units of m.w. 2000 are highly extensible elastomers. Those with higher m. w. polyetoher blocks have higher modulus and strength but suffer a serious loss of properties at 60 C. The observations are interpreted in terms of a model in which polyester crystallites (and polyether crystallites also, for the higher m. w. polyether blocks) are supported within an amorphous matrix by tie-molecules whose nature changes with the copolymer compositions. The results are compared with those for analogous polyester-polyethers having different structural components.
Polymer Testing, 2008
A series of novel thermoplastic block copolymers (BCPs) based on an aliphatic copolyamide and an oligodiene having isocyanate end groups were prepared to obtain new thermoplastics with improved properties. The structure of the new block copolymers was controlled by the molar ratio of components and monitored by the means of IR and 1 H NMR spectroscopy. The morphology of the BCPs was investigated using electronic microscopy (SEM), thermal behaviour was evaluated by differential scanning calorimetry (DSC) and mechanical properties were studied by specific tests. Starting from these BCPs and using polyethylene waste (secondary polyethylene s-PE), new polymeric blends were obtained and subsequently characterized. A morphology study was performed and mechanical characteristics of these blends comparatively evaluated. We concluded that the new block copolymers can be successfully used as a component of such blends for the recovery of polymeric waste, a viable alternate solution for waste management.