Compatibilizing effect of styrene–maleic anhydride copolymer on the properties of polyamide‐6/liquid crystalline copolyester composites

Liquid crystalline polymer–polyamide‐6 (LCP/PA6) composites containing 20 wt % LCP content were compatibilized by a random styrene–maleic anhydride copolymer (RSMA). The blending was performed via extrusion followed by injection molding. The LCP employed was a commercial copolyester, Vectra A950. The dynamic mechanical (DMA), rheological, thermal, and mechanical properties as well as the morphology of the composites were studied. The DMA and rheological results showed that RSMA is an effective compatibilizer for LCP/PA6 blends. The mechanical measurements showed that the stiffness, tensile strength, and toughness of the in situ composites are generally improved with increasing RSMA content. However, these mechanical properties deteriorated considerably when RSMA content was above 10 wt %. The drop‐weight dart impact test was also applied to analyze the toughening behavior of these composites. The results show that the maximum impact force (F_max) and crack‐initiation energy (E_init) tend to increase with increasing RSMA content. From these results, it appeared that RSMA prolongs the crack‐initiation time and increases the energies for crack initiation and impact fracture, thereby leading to toughening of LCP/PA6 in situ composites. Finally, the correlation between the mechanical properties and morphology of the blends is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1964–1974, 2000     

Work of fracture of polystyrene/high density polyethylene blends compatibilized by triblock copolymer

The fracture toughening behavior of polystyrene/high density polyethylene blends compatibilized by 10 wt % of a styrene‐ethylene‐butylene‐styrene triblock copolymer (SEBS) was assessed using single‐edge notched tension (SENT) and double‐edge notched tension (DENT) specimens of various gauge lengths over a wide range of tensile rates. The fracture of DENT and SENT specimens was completely ductile under the plane‐stress condition. A linear relationship was observed between the specific total work of fracture and the ligament length (L) for a given L range. The results showed that the essential work (w_e) was independent of the tensile rate (R) range of 1–30 mm/min, and it then decreased considerably when R was increased to 50 mm/min and above. However, the nonessential work exhibited a rate independent trend behavior. In addition, w_e and the specific nonessential work of fracture (βw_P) were basically independent of the gauge length (G), provided that G was greater than the width of the sample. Finally, it was also shown that the w_e and βw_P values for SENT specimens are obviously greater than those for DENT specimens. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2074–2081, 2000     

Mechanical and thermal behavior of poly(acrylonitrile-butadiene-styrene)/polycarbonate blends reinforced with potassium titanate whiskers

Poly(acrylonitrile-butadiene-styrene) (ABS)/polycarbonate (PC) blends reinforced with potassium titanate (K₂Ti₆O₁₃) whiskers were prepared in a twin screw extruder followed by injection molding. The whiskers were pretreated with tetrabutyl orthotitanate prior to compounding. The tensile, dynamic mechanical, impact, morphology and thermal properties of the blends were studied. Tensile tests showed that the modulus of ABS/PC/K₂Ti₆O₁₃ blend increased markedly with increasing whisker content. However, the variation of the modulus of ABS/PC/K₂Ti₆O₁₃ blend with PC content followed a sigmoidal relation. In addition, the tensile strength of the blends containing 20 wt% PC tended to increase markedly with increasing whisker content. But the impact strength of the blends containing 20 wt% PC decreased rapidly with increasing whisker content. Dynamic mechanical analyses (DMA) results indicated that the storage modulus of the blends increased markedly with increasing K₂Ti₆O₁₃ whisker content. Differential thermal analysis and thermogravimetric measurements showed that potassium titanate whiskers tend to induce chemical decomposition of PC during blending of the PC/whisker blends. However, the incorporation of ABS into PC was beneficial to reduce the PC decomposition during compounding with the whiskers.     

Impact-modified blends of compatibilized polyamide-6 with liquid crystalline copolyester

Compatibilized blends of polyamide-6 (PA6) and thermotropic liquid crystalline polymer (LCP) modified with various high-impact polypropylene (HIPP) contents were injection-molded. These blends were compatibilized with maleic anhydride-grafted polypropylene (MAP). The effects of impact modification on the morphology, impact, static, and dynamic mechanical properties were investigated. The results showed that the HIPP addition leads to an improvement of the Izod impact strength of the blends significantly while it reduced the tensile strength and stiffness properties. An attempt was made to correlate the structure of the PA6(MAP)/HIPP/LCP blends from the scanning electron microscopic observations with the measured mechanical properties. This work provides a way to produce a tough in situ composite. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1611–1619, 1998     

Synthesis and properties of poly(aryl ether sulfone)s containing the phthalazinone moiety

Three series of poly(aryl ether sulfone)s (PAESs) containing the phthalazinone moiety in the polymer backbone were synthesized by solution polycondensation of bis(4-chlorophenyl) sulfone with three commercial bisphenols and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one. Bisphenol-A, hydroquinone, and bis(4-hydroxyphenyl) sulfone, or bisphenol-S, were selected as the commercial bisphenols for copolymerization. The synthesized polymers exhibited very high glass transition temperatures and excellent thermooxidative properties. They also showed superior mechanical properties and fair rheological properties. The introduction of relatively flexible moieties, such as benzene rings, onto the poly(phthalazinone ether sulfone) (PPES) chain led to a decrease in glass transition temperature with respect to the phthalazinone homopolymer. However, the processability of PPES was improved dramatically by the addition of these commercial bisphenols. The properties of synthesized PAESs can be tailored by changing the molar ratios of bisphenols to phthalazinone monomer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:137–143, 1998     

Synthesis of novel poly(phthalazinone ether sulfone ketone)s and improvement of their melt flow properties

A series of novel poly(phthalazinone ether sulfone ketone)s was synthesized from bis(4-fluorophenyl) ketone, bis(4-chlorophenyl)sulfone, and 4-(4-hydroxybenzyl)-2,3-phthalazin-1-one through nucleophilic substitution polycondensation. The synthesized polymers exhibited surprisingly high glass transition temperatures and had excellent thermooxidative properties. The melt viscosities of these synthesized polymers are generally too high to be processed by common processing methods because of their very high glass transition temperatures and amorphous microstructure. An attempt was made to reduce their melt viscosities by solution blending the synthesized polymer with two kinds of oligomers: low molecular weight poly(phthalazinone ether sulfone ketone) and commercial poly(ether sulfone). The results proved that the addition of the oligomers to the polymers led to a marked decrease in melt viscosities. Furthermore, no obvious changes were observed in the thermal and mechanical properties of these blends after oligomer additions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1425–1432, 1997     

Impact fracture behavior of PP/EPDM/glass bead ternary composites

The effects of glass bead filler content and surface treatment of the glass with a silane coupling agent on the room temperature impact fracture behavior of polypropylene (PP)/ethylene‐propylene‐diene monomer copolymer (EPDM)/glass bead(GB) ternary composites were determined. The volume fraction of EPDM was kept constant at 10%. The impact fracture energy and impact strength of the composites increased with increasing volume fraction of glass beads (?_g). Surface pretreatment of the glass beads had an insignificant effect on the impact behavior. For a fixed filler content, the best impact strength was achieved when untreated glass beads and a maleic anhydride modified EPDM were used. The impact strength exhibited a maximum value at ?_g=15%. Morphology/impact property relationships and an explanation of the toughening mechanisms were developed by comparing the impact properties with scanning electron micrographs of fracture surfaces.     

Hybrid biocomposites with enhanced thermal and mechanical properties for structural applications

The current work focuses on enhancing the mechanical and thermal properties of sisal fiber reinforced composites that were previously used in developing interior automotive trims. In order to extend their use in other structural applications, two hybrid biocomposites with the combination of sisal (SF) and glass fiber (GF)‐SF20/GF10 and SF10/GF20 were blended with polypropylene via extrusion and injection molding process. Critical material properties such as density, fogging, acoustic, mechanical, thermal, and rheological properties were evaluated and results were analyzed using ANOVA. Hybridization of SF and GF enhanced flexural strength and thermal properties of the biocomposites by 33 and 19%, respectively, while no significant change in acoustic, impact and rheological properties were observed. The properties of the hybrid biocomposites were compared with the material specification of a battery tray and it was found that these hybrid biocomposites could be better alternative materials in structural applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42452.     

Biodiesel engine performance and emissions in low temperature combustion

Engine performance and emission comparisons were made between the use of soy, Canola and yellow grease derived B100 biodiesel fuels and an ultra-low sulphur diesel fuel in the high load engine operating conditions. Compared to the diesel fuel engine-out emissions of nitrogen oxides (NO_x), a high-cetane number (CN) biodiesel fuel produced comparable NO_x while the biodiesel with a CN similar to the diesel fuel produced relatively higher NO_x at a fixed start of injection. The soot, carbon monoxide and un-burnt hydrocarbon emissions were generally lower for the biodiesel-fuelled engine. Exhaust gas recirculation (EGR) was then extensively applied to initiate low temperature combustion (LTC) mode at medium and low load conditions. An intake throttling valve was implemented to increase the differential pressure between the intake and exhaust in order to increase and enhance the EGR. Simultaneous reduction of NO_x and soot was achieved when the ignition delay was prolonged by more than 50% from the case with 0% EGR at low load conditions. Furthermore, a preliminary ignition delay correlation under the influence of EGR at steady-state conditions was developed. The correlation considered the fuel CN and oxygen concentrations in the intake air and fuel. The research intends to achieve simultaneous reductions of NO_x and soot emissions in modern production diesel engines when biodiesel is applied.     

Loading Rate Dependence of Mode II Fracture Behavior in Interleaved Carbon Fibre/Epoxy Composite Laminates

The mode II delamination fracture toughness (G _IIC ) for interleaved and non-interleaved CFRP were measured at loading rates ranging from 0.2 to 125 mm/min. It was observed that interleaving could enhance G _IIC for CFRP significantly. Furthermore, G _IIC was observed to be independent of the loading rate for the non-interleaved CFRP. For the interleaved CFRP, the loading rate has a strong influence on G _IIC , and the loading rate dependence can be explained in terms of the fracture surface morphologies.