Sani Amril Samsudin

Effects of compatibilizers on mechanical properties of PET/PP blend

Polyethylene terephthalate (PET) and polypropylene (PP) are incompatible thermoplastics due to differences in chemical structure and polarity hence their blends posses inferior mechanical properties. Compatibilization with a suitable block/graft copolymer is one way to improve the mechanical properties especially impact strength of such a blend. In this work, the effects of two compatibilizers, maleic anhydride grafted polypropylene (PP-g-MAH) and maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH), were investigated for compatibilization of PET/PP blends and the results were compared. PET, PP, and compatibilizers were melt blended in a single step using a counter-rotating twin screw extruder with compatibilizer concentrations 0, 2, 4, 6, 8, and 10 phr, respectively. Standard test samples were prepared by injection molding process. The resulting compatibilized blends were characterized by tensile, flexural, and impact tests. The results showed improvements in mechanical properties of the blends due to the in situ polymerization reaction between the ester groups of PET and the maleic anhydride (MAH) during melt extrusión. The incorporation of 4 phr PP-g-MAH in the blends resulted in the highest tensile and flexural strength, while no significant improvements in Young’s modulus were observed for both compatibilized blends. The máximum impact strength of the blends was obtained at 8 phr of SEBS-g-MAH. Improvement of impact strength of the blends may be attributed to the elastomeric nature of the SEBS-g-MAH while greater improvement recorded for tensile and flexural strength is likely to be due to the affinity between PP-g-MAH with PP of the blend. Scanning electron microscopy shows the addition of PP-g-MAH and SEBS-g-MAH compatibilizers into the blends promote a better dispersión of PP into PET matrix.

Effect of SEBS on the mechanical properties and miscibility of polystyrene rich polystyrene/ polypropylene blends

Blends of polystyrene (PS) with polypropylene (PP) are usually developed to overcome the inherent brittleness of PS. However, PS with PP are immiscible and (in the absence of a compatibiliser) incompatible. The present study investigated the effects of styrene-b (ethylene-co-butylene)-b-styrene (SEBS) on the mechanical properties and compatibility of PS-rich PS/PP blends. Using a Brabender PL2000 twin-screw extruder, blends of PS/PP in various compositions ranging from 100-60 wt% PS with and without SEBS were prepared and injection moulded. The overall results clearly showed that the mechanical properties of PS/PP blends are dependent on blend composition (ratio of PS/PP) and SEBS content. The impact strength and elongation at break of the PS/PP blends increase with SEBS content, at the expense of tensile strength and flexural modulus. The improvements in impact strength and elongation at break with the addition of SEBS are due to the improved interfacial adhesion between the dispersed phase (PP) and matrix phase (PS). The improvement in miscibility of the PS/PP blend with the addition of SEBS is supported by DMA analysis. This showed that the 60/40 PS/PP blends possess two endothermic peaks whereas 60/40/25 PS/PP/SEBS blends have a single endothermic peak at 102 °C, indicating that they have an improved miscibility. The effectiveness of SEBS in enhancing the blends depends on the blend composition. A significant improvement was observed upon addition of more than 10 phr of SEBS into the 70/30 and 60/40 PS/PP blends, but not much improvement in the case of the 90/10 and 80/20 PS/PP blends. However, a higher SEBS content is more effective at higher PS contents, as illustrated by the 90/10/25 PS/PP/SEBS blends having higher impact strengths than 60/40/25 PS/PP/SEBS. The optimum blend, based on achieving a balance between toughness (impact strength) and stiffness (flexural modulus), is 90/10/25 PS/PP/SEBS, followed by 80/20/25 PS/PP/SEBS.

Mechanical properties of chitosan modified montmorillonite filled tapioca starch nanocomposite films

This study was carried out to develop renewable and degradable plastics film with good mechanical properties. The mechanical properties between compatibilized montmorillonite (MMT)/chitosan filled tapioca starch (TPS), uncompatibilized MMT/TPS, and chitosan/TPS nanocomposite films were investigated. Experimental works were started with the extraction of local chitosan from chitin derived from prawn shells which involving deprotenization, demineralization and deacetylation treatments. Degree of deacetylation of chitosan was determined using infrared spectroscopy method. Chitosan was acted as compatibilizer between MMT and starch in order to improve the dispersion of MMT in nanocomposite systems. Nanocomposite films were prepared using a solution casting method with addition of glycerol as the plasticizer. The starch solution was cast onto PTFE mold with cavity thickness of 0.5mm. Characterizations of the nanocomposite films were done using Fourier Transform Infrared Analysis (FTIR). Tensile properties of nanocomposites were investigated. The compatibilized nanocomposite films, chitosan/MMT/TPS give significant effects to tensile properties. Chitosan has played its role as the compatibilizer and also as flexibility improvers to nanocomposite films because elongation at break improved after addition of chitosan.

Mechanical and physical properties of chitosan-compatibilized montmorillonite-filled tapioca starch nanocomposite films

Chitosan-compatibilized montmorillonite-filled plasticized tapioca starch (thermoplastic starch) nanocomposite films were produced using a solution casting method. Chitosan used was prepared and produced from the local shrimp shells. X-ray diffraction analysis showed that the interlayer spacing of the chitosan-compatibilized montmorillonite/thermoplastic starch films was slightly increased which indicated that the chitosan was too large to intercalate into the clay galleries. However, a scanning electron microscopy analysis showed that the compatibilized films produced a more homogeneous distribution of montmorillonite nanoclay particulate compared to the uncompatibilized films. The water vapor transmission rate, water absorption, and light absorbance thermoplastic starch films decreased with increasing chitosan and decreasing montmorillonite content. The increased chitosan content from 5 to 9 wt% with decreased montmorillonite content from 7 to 3 wt% improved flexibility about 53%, water resistance 66%, water vapor transmission rate resistance 9%, and thermoplastic starch film light transmission with a moderate decrease, tensile strength about 12% and tensile modulus about 99%. Generally, the chitosan successfully acted as a compatibilizing agent between montmorillonite and starch by improving the properties, particularly on film flexibility, which is utilized for food packaging.

Effect of Compatibilizer Content on the Mechanical and Morphological Properties of PET/PP (70/30) Blends

This work investigates the effect of compatibilizer concentration on the mechanical properties of compatibilized polyethylene terephthalate (PET) /polypropylene (PP) blends. A blend containing 70 % (wt) PET, 30 % (wt) PP and 5 - 15 phr compatibilizers were compounded using counter rotating twin screw extruder and fabricated into standard test samples using injection molding. The compatibilizer used is styrene-ethylene-butylene-styrene grafted maleic anhydride triblock copolymer (SEBS-g-MAH). Morphological studies show that the particle size of the dispersed PP phase is dependent on the compatibilizer content up to 10 phr. Impact strength and elongation at break showed maximum values with the addition of 10 phr SEBS-g-MAH and a corresponding decrease in flexural and young’s moduli; and strengths.. Overall the mechanical properties of PET/PP blends depend on the control of the morphology of the blend and can be achieved by effective compatibilization using 10 phr SEBS-g-MAH.