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The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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The non-isothermal crystallization kinetics of poly (Llactide) (PLLA) from the melt was studied in presence and absence of single wall carbon nanotubes (SWCNT) by differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM). The results indicate that SWCNT acting as nucleation sites for PLLA crystallization have a significant effect on all the crystallization parameters studied: crystallinity index (Xc) crystallization temperature (Tc) spherulite growth rate (G) morphology and Avrami’s kinetics parameters (n k and t1/2). The existence of a critical concentration of SWCNT that provides the maximum changes in crystallization behavior of PLLA was determined.
The non-isothermal crystallization kinetics of poly (L-lactide) (PLLA) from the melt was studied in presence and absence of single wall carbon nanotubes (SWCNT) by differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM). The results indicate that SWCNT acting as nucleation sites for PLLA crystallization have a significant effect on all the crystallization parameters studied: crystallinity index (Xc), crystallization temperature (Tc), spherulite growth rate (G), morphology, and Avramiƒ??s kinetics parameters (n, k and t1/2). The existence of a critical concentration of SWCNT that provides the maximum changes in crystallization behavior of PLLA was determined.
Recycled polyethylene terephthalate (RPET) recycled polypropylene (RPP) and CaCO3 were blended and compatibilized with SEBS copolymer. The effects of compatibilization on morphological thermal and mechanical properties were investigated. The results indicated that the dispersed phase in compatibilized blends is significantly smaller in size as compared to uncompatibilized blends. The crystallization temperature and crystallinity of the blends were affected by the incorporation of compatibilizers while tensile and impact properties depended on the content of CaCO3 and compatibilizer.
Recycled polyethylene terephthalate (RPET),recycled polypropylene (RPP) and CaCO3 were blendedand compatibilized with SEBS copolymer. The effects of compatibilization on morphological, thermal and mechanical properties were investigated. The results indicated that the dispersed phase in compatibilized blends is significantly smaller in size as compared to uncompatibilized blends. The crystallization temperature and crystallinity of the blends were affected by the incorporation of compatibilizers while tensile and impactproperties depended on the content of CaCO3 and compatibilizer.
There is very severe difference of tear property of polyethylene blown films observed depending on the location of tear sampling sometimes. Tear values of some polyethylene blown films are very scattered, and those data are statistically meaningless. Especially, it is known that the formation of haze bands can affect the tear property of polyethylene blown films. So, in this study, for understanding of the variation of tear property of polyethylene blown films, various scientific analyses based on both of fracture mechanics (for macroscale) and materials science (for microscale) are used to analyze the effect of haze bands of polyethylene blown films.
Talc filled polypropylene (PP) composites filled with different loadings of talc were die-drawn at 15?øC below the melting temperature using different draw rates. The objective was to study the effect of draw rate on polymer orientation and flexural modulus achieved in the presence of particles, along with void growth and deformation. A lower extent of crystalline orientation was achieved in the drawn PP-talc composite with 7.8 vol% of talc than in the drawn composite with 3.5 vol% of talc and in the drawn neat PP. The crystalline c-axis orientation was independent of draw rate over the range studied while the void volume fraction, the mean void aspect ratio and the flexural modulus leveled off only at higher draw rates. The effect of voiding in drawn composites appeared to be offset by the increased orientation in amorphous polymer regions.
The effect of notches was investigated by introducing single-edge hairline cracks and V-shaped notches of different depths on dumbbell samples to ascertain the fracture behavior at the skin and core parts of virgin and recycled poly(ethylene terephthalate) (V-PET/R-PET) injection-moldings. Investigation shows that the fracture behavior of the materials responded differently to both hairline crack and V-shaped notch. Results revealed that a mere 5?m deep critical hairline crack caused a drastic change in the fracture behavior of the materials. In contrast a standard V-shaped notch would only cause drastic change in toughness at a much higher critical notch depth of 600?m. V-shaped notch also provided a gradual transition in fracture behavior from the skin to the core regions which suggests that the fracture behavior can be dependent on the skin and core sizes of PET injection moldings.
The effect of notches was investigated by introducing single-edge hairline cracks and V-shaped notches of different depths on dumbbell samples to ascertain the fracture behavior at the skin and core parts of virgin and recycled poly(ethylene terephthalate), (V-PET/R-PET), injection-moldings. Investigation shows that the fracture behavior of the materials responded differently to both hairline crack and V-shaped notch. Results revealed that amere 5?¬m deep critical hairline crack caused a drasticchange in the fracture behavior of the materials. In contrast, a standard V-shaped notch would only cause drastic change in toughness at a much higher critical notch depth of 600?¬m. V-shaped notch also provided a gradual transition in fracture behavior from the skin to the core regions, which suggests that the fracture behavior can be dependent on the skin and core sizes of PET injection moldings.
Poly(vinyl alcohol) (PVA) has been esterified with lactic glycolic and butyric acids to modify its compatibility with poly (?-caprolactone) (PCL). The extent of the chemical reaction in PVA was followed by 13C NMR. The analysis of miscibility of the blends was conducted by differential DSC FTIR and AFM. Phase separation was observed by DSC and FTIR suggesting that auto-association of the H-donor counterpart is a key negative factor impairing its miscibility with polylactide. In addition AFM results show a finely dispersed phase of decreasing size as the extent of the modification of the PVA increases suggesting improved compatibility for the modified systems.
Poly(vinyl alcohol) (PVA) has been esterified with lactic, glycolic and butyric acids to modify itscompatibility with poly (?æ-caprolactone) (PCL). Theextent of the chemical reaction in PVA was followed by13C NMR. The analysis of miscibility of the blends wasconducted by differential DSC, FTIR, and AFM. Phase separation was observed by DSC and FTIR, suggesting that auto-association of the H-donor counterpart is a key negative factor impairing its miscibility with polylactide.In addition, AFM results show a finely dispersed phase of decreasing size as the extent of the modification of the PVA increases, suggesting improved compatibility for the modified systems.
Flow simulations and coextrusion experiments were employed to characterize layer sequencing effects on the interfacial stability of coextruded five-layered films incorporating ballistic-resistant materials. A simple model of coextrusion was able to rank the relative coextrusion stability of multilayered structures qualitatively in terms of viscosity matching and viscoelastic considerations. However thermal analyses and coextrusion experiments revealed that the overriding factor determining coextrusion performance was the thermal stability and degradation characteristics of the materials utilized to produce the multilayered films. Therefore any predictive analysis of coextrusion should also consider appropriate degradation mechanisms and their affect upon melt rheology.
Flow simulations and coextrusion experiments were employed to characterize layer sequencing effects on the interfacial stability of coextruded five-layered films incorporating ballistic-resistant materials. A simple model of coextrusion was able to rank the relative coextrusion stability of multilayered structures qualitatively in terms of viscosity matching and viscoelastic considerations. However, thermal analyses and coextrusion experiments revealed that the overriding factor determining coextrusion performance was the thermal stability and degradation characteristics of the materials utilized to produce the multilayered films. Therefore, any predictive analysis of coextrusion should also consider appropriate degradation mechanisms and their affect upon melt rheology.
Polymer gel electrolyte is one of the most useful solid electrolytes for replacing conventional liquid electrolytes. To overcome the drawbacks from conventional electrolytes solvent, ion gels by in situ polymerization of methylmethacrylate (MMA) in hexafluorophosphate (BMIPF6) were developed with crosslinking agent. Ion gels were prepared with respect to weight ratio of MMA/BMIPF6. The transparent, self-standing and flexible ion gels with high ambient ionic conductivity and good thermal stability were obtained. The ion transfer behavior and its temperature dependency were investigated. The structure of crosslinked network of ion gels were observed by optical microscope and confirmed with swelling ratio test.
This project aims to investigate the material properties of Polylactic acid (PLA) and to compare them with Polyvinyl chloride (PVC) which is currently used in retail signage. There problems inherent in changing a process from an established material to a biodegradable polymer. The mechanical properties of PLA are under scrutiny to determine if it can be a reasonable substitute for PVC a non biodegradable plastic that must be land-filled or recycled at considerable cost after its post-consumer use. Many environmentalists suggest that biodegradable plastics can be substituted to fill the same roles as conventional polymers. PLA is a biodegradable polymer that is available in grades that are transparent and are manufacturable in most common thermoplastic processing methods including extrusion. PLAƒ??s substitution for PVC in this application can help to eliminate landfill and reduce overall pollution.
Life cycle analysis (LCA) is an accepted methodology to determine the environmental impact of a certain material or package at different stages in its product life. In some cases however LCAs can be complex and expensive to carry out. DuPont is looking at ways to internally estimate the LCA of its products by using a modular approach: building estimates of nonrenewable energy and green house gas emissions by summing proprietary information on our ingredients and unit operations. The output of this tool will be used to target our internal improvement efforts and potentially help our value chain partners make better multilayer flexible packaging design choices.
Life cycle analysis (LCA) is an accepted methodology to determine the environmental impact of a certain material or package at different stages in its product life. In some cases, however, LCAs can be complex and expensive to carry out. DuPont is looking at ways to internally estimate the LCA of its products by using a modular approach: building estimates of nonrenewable energy and green house gas emissions by summing proprietary information on our ingredients and unit operations. The output of this tool will be used to target our internal improvement efforts and potentially help our value chain partners make better multilayer flexible packaging design choices.
A newly developed injection molding machine equipped with a screwless/two-plunger injection unit has been employed to mould miniaturized dog-bone shaped specimens on polyoxymethylene and its process capability and robustness have been analyzed. The influence of process parameters on ?¬-injection molding was investigated using the Design of Experiments technique. Injection pressure and piston stroke speed as well as part weight and dimensions were considered as quality factors over a wide range of process parameters. Experimental results obtained under different processing conditions were evaluated to correlate the process parameter levels influence on the selected responses, considering both average values and standard deviations.
Using a nano-bubble inflation technique developed in our lab we have measured the absolute creep compliance of polymer films down to a thickness of 9nm [1-3]. Materials studied were a poly (vinyl acetate) (PVAc), a polystyrene (PS) and a polycarbonate (PC). All three materials showed dramatic stiffening of the rubbery plateau compliance as the thickness was reduced below approximately 100nm, with the stiffness increasing by some three orders of magnitude for the thinnest films. In the region where the stiffness is thickness dependent, the stiffness of all three materials varies as approximately the inverse of the square of the thickness. Interestingly, while the change in stiffness was common to all materials, the reduction in the glass transition temperature which is commonly observed in thin free standing films was very different. The PS showed a decrease of approximately 50K at a thickness of 11nm which is comparable to literature data. The PVAc showed no change in Tg down to 23nm while the PC showed a large decrease of ~90K at 9nm.
The efficiency of using a cryogenic milling device for mixing a polymer with highly agglomerated multi-walled carbon nanotubes, to create polymer nanotubes nanocomposite, was evaluated. PEO/CNT and PE/CNT nanocomposites studied contained 1% and 2% of MWCNTs, and were blended in a cryogenic milling apparatus using two sizes of milling balls, and different milling times. The nanocomposites were characterized using SEM and DSC. Intimate contact between polymeric matrices and the CNTs was observed through SEM analysis. The thermal analysis results showed small variations in the transition temperatures of the nanocomposite when compared with the unfilled polymers.
Oriented Polypropylene/Cast Polypropylene (OPP/CPP) film is made by laminating OPP and CPP which is widely used as general packaging material. OPP functions as a moisture resistant layer while CPP provides better heatsealability. In earlier investigations effects of heat-sealing temperature on properties of heat-sealed OPP/CPP film were investigated. The optimum heat-sealing temperature was found to be 140°C. In this study different seal pressures were used at 140°C. It was revealed that the peel strength is dependant on the seal pressure whereby the maximum peel strength was achieved at 0.03 MPa. The mechanical properties on the heat sealed part were examined by means of tensile test with circular notch peel test and scanning electron microscopy.
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