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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Nondestructive Characterization of Orientation in Thick Cast and Drawn Polyaniline Films
Polyaniline (PANI) films 20 to 50 microns thick cast from N, N’-dimethylpropylene urea (DMPU) solution and stretched to different draw ratios were examined. The thickness of these visibly opaque PANI films posed severe limitations on available structural characterization tools. NIR wave guide coupling, X-ray diffraction and FTIR infrared dichroism methods were used. Two new infrared transition moment angles for weakly absorbing bands were determined for the PANI molecule. This allowed the Hermans’ orientation function for the thick PANI films to be determined nondestructively.
Improving Gel Compatibility of Polyolefinic Polymers for Loose Buffer Tubes in Fiber Optic Cables
Loose buffer tube designs in fiber optic cables (FOC) generally include hydrocarbon oil based gels to fill the tubes for mechanical and moisture protection. Conventional olefinic polymers typically show reduced performance in compatibility testing due to a high level of hydrocarbon oil permeability. In particular, impact-modified polypropylene (IMPP) requires specially formulated and, therefore, more expensive gels to retain modulus and tensile properties after oil exposure. Described herein is the gel compatibility performance of a developmental product made with INSPIRE* Performance Polymers that provide a substantially improved balance of impact toughness, high modulus and gel compatibility for the optic buffer tube application versus the conventional polyolefin materials currently used. Also outlined are preliminary results of ongoing material studies targeting further improvement in gel compatibility performance.
Investigation of Packaging Properties as a Function of Filler Microstructure
Fillers are used in the molding compounds to minimize the stress of electronic packaging by reducing the coefficient of thermal expansion (CTE) mismatch between the silicon die and the molding compounds.This study concentrates on the effect of filler particle spatial distribution. Quantitative measures of the particle distribution were experimental determined, including area fraction, size and interparticle distance (IPD). A 2×3×3 ANOVA test was also conducted to assess the statistical significance of these variations of measures. The difference of filler volume fraction at different positions within one chip can be as big as 10%, and cause a CTE difference of about 4 ppm/°C.
Conductive Polymer Blends for Injection-Molded Bipolar Plates
This work aims at developing lightweight low-cost bipolar plates for use in proton exchange membranes (PEM) fuel cells. New material formulations using polypropylene (PP) and polyphenylene sulfide (PPS) as matrices and carbon black, graphite, and carbon fibers as conductive additives were developed. These formulations have properties suitable for bipolar plate manufacturing, such as good chemical resistance, sufficient fluidity, and high electrical and thermal conductivity. Two prototype plates of different design were successfully fabricated by over-molding aluminum plates or simply by injecting the high conductive materials into the final shape.
Experimental Study for Underfill of Flip-Chip Packages
Today, most flip chips are encapsulated by dispensing the encapsulant along the periphery of the sides of chip. As the dispensing process fills the space between chip and substrate by capillary force, the flow is very slow and could result in filling incomplete or voids. Therefore, as chip size increases, the filling problems become more serious. For this reason, it is critical for flip-chip technology to speed up the encapsulation process and avoid defects.This paper studies the theories of the material properties, contact angle and surface tension,etc. Moreover, some transparent molds with different number/size of bumps and different layout patterns are used to study molding phenomena. The experimental results are further used to verify the use of CAE tools.
Failure of Plastic Plumbing Products
Failures of plastic components are being seen more often in industrial, household and commercial settings. Many of these failures involve the transport of water and cause significant damage when they occur. These failures can be caused by improper material specification, bad design, over loading or incorrect molding conditions. Issues such as chemical resistance, environmental deterioration, geometric sensitivity, temperature dependence and aging are at times overlooked.
Reliability of Joining Plastic Parts
Critical items in designs of plastic products are joints. The paper will deal with a number of design aspects about designing reliable plastic products. It will combine the results from our research in the field of stress concentrations, orientation and weld lines around holes, embrittlement of polymers, adhesion and environmental stress corrosion. A number of failures in practice will be presented.
Performance Characteristics of a Styrene-Isobutylene Block Copolymer Produced by Living Cationic Polymerization Technology
A completely saturated styrene-isobutylene based thermoplastics elastomer has been produced at the industrial scale for the first time. Triblock (SIBS) of Mw range 65,000 to 100,000 have been produced. Due to the saturated main chain of polyisobutylene, these products are superior in heat rersistance, gas barrier properties and damping properties.
Nano-Composites via Solid-State Modification for Toughening in Semi-Crystalline Polymers
Chemical modification of isotactic polypropylene in solid-state using various monomers –initiator systems has been investigated. In particular porous iPP is modified in solid-state by grafting silanes or acrylates using free radical initiators. Silica like nano-particles were formed in-situ via sol-gel reaction in pre-modified solid porous iPP. These silica-clusters were of nano-scale varying from 30-200 nm in size, and retained the size even after processing (extrusion). Grafting and silica formation via sol-gel is characterized using FT-IR and 29Si Solid-state NMR. Morphological characterization (using TEM and SEM) showed uniform distribution and dispersion of silica particles in matrix before and after processing. DSC and WAXD results revealed that silanes, when grafted on iPP, nucleate and induce ?-phase. Improvement in toughness and effect on thermal properties of polymer were also investigated and mechanism of toughness enhancement is proposed.
Polypropylene/Clay Nanocomposites: Characterization and Interpretation of Structure - Property Relationships
Polypropylene (PP) nanocomposites were obtained by melt compounding of PP and organoclays in the presence of maleic anhydride grafted polyolefin compatibilizer. The effects of compatibilizer type and content and the mixing sequence on the morphology and properties of the PP/clay nanocomposites were investigated. PP nanocomposites exhibit enhanced mechanical properties compared with neat PP and they also are thermally more stable. Rheological properties are sensitive to the composite structure and thus are a valuable indication of the degree of exfoliation.
Novel Nanostructured Polymer Blends with Enhanced Benefits
Molecular-level blending of reactive polymers can provide an alternative and economical route to producing new polymers with special structures and improved properties. In this paper, we report results of our experimental efforts to generate compatibilized polypropylene (PP)/polyamide 6 (PA6) blend via in situ polymerization and in situ compatibilization of polypropylene, ? -caprolactam and maleic anhydride grafted PP that is impossible to achieve using conventional polymer blending methods reported in the literature. The intrinsic molecular-level blending and compatibilization of the preparation method allowed formation of nanostructured PP/PA6 blends with interesting stable interpenetrating or co-continuous morphologies that can be controlled during processing. Thermal and morphological measurements revealed that the compatibilization effect of the blend is significantly better than that obtained from conventional reactive blending of premade polymers. With proper control of the thermodynamics, interfacial tension (through use of chemically modified functional polymer) and deformation rates, particle coalescence could be suppressed, making it possible to generate the polymer blends with very small (< 100 nm) polydispersities. These blends could find applications in a number of high-end uses such as optics, drug delivery, tissue engineering, and permeable membranes for separation phenomena.
PBT and PET Ionomer Based Clay Nanocomposites
Poly(butylene terephthalate), poly(ethylene terephthalate) and their respective ionomers were utilized as matrices in the formation of organically-modified montmorillonite clay nanocomposites. These materials were prepared using melt extrusion with a variety of clay concentrations. The small angle x-ray scattering and transmission electron microscopy data revealed that low levels of sulfonation in the polyester ionomers resulted in exfoliated clay nanocomposites. Moreover, the orientation of the clay platelets within injection molded dogbones was found to increase with increasing sulfonation level of the ionomers. The affect of clay dispersion on the thermal and mechanical properties of the nanocomposites was investigated. The enhancements in mechanical properties produced by the ionic functionality were attributed to an increase in the number of interactions between the clay platelets and the matrix via electrostatic interactions involving the sodium sulfonate groups. In addition, a tentative model of how the negatively charged, sulfonate groups along the polymer chains interact with the montmorillonite clay platelets to improve the exfoliation of the clay platelets was provided.
Performance Enhancing Crosslinked SBR Masterbatches for Thermoplastic Elastomers
Masterbatches of crosslinked solution-polymerized styrene-butadiene random elastomers (XL-SBR) and polypropylene (PP) were prepared and used for enhancing the oil resistance, compression stress relaxation performance, lowering gloss, and compression set of styrene-ethylene/butylene-styrene (SEBS)-based thermoplastic elastomer (TPE) compounds. Enhanced performance was achieved when SBR partly or substantially replaced the SEBS component. Modification of SEBS compounds in the Shore A range of 45-85 with the crosslinked SBR is discussed.
New Soft EPDM Rubber Concentrate for Toll Compounding to Produce High Flow Thermoplastic Vulcanizates (TPVs) for Injection Molding Applications
New soft EPDM rubber concentrate can be used to produce thermoplastic vulcanizates (TPVs) with improved flow properties by toll compounding processes for injection molding applications. By adding various amounts of polyolefin plastics such as polypropylene homo polymer or copolymers, TPVs with different durometers and properties can be made easily using compounding equipment such as twin screw extruders or other mixing equipment with sufficient mixing capability.
New Thermoplastic Vulcanizates (TPVs) with Improved Processibility for Injection Molding Applications
A new line of thermoplastic vulcanizates (TPVs) has been introduced by DSM Thermoplastic Elastomers for injection molding applications where UV resistance is critical. This new line of products, consisting of several grades with hardness ranging from 50 to 85 shore A in black color, shows superior flow characteristics and balanced properties meeting existing automotive material specifications. In this paper, we will discuss some of the features associated with this new line of products.
Effect of Crystalline Structure on Tear Resistance of LDPE and LLDPE Blown Films
Low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) blown films differ significantly in the ratio between machine and transverse direction tear resistance. In this paper, the relation between crystalline morphology and these differences in film tear anisotropy was investigated. The crystalline morphology and its orientation were probed using microscopy and infrared spectroscopy. Significant differences in crystalline morphology were found: LDPE develops a row-nucleated structure, while a spherulitic-like superstructure was observed for LLDPE. These structural differences were shown to translate into different ratios of machine and transverse directions tear strengths.
Effect of Processing Parameters on Properties of LLDPE-Based Mono- and Multilayered Blown Films
In this paper we investigated the effect of processing parameters on end-use mechanical properties of monolayer and 5-layer coextruded polyethylene blown films using three different linear low density (LLDPE) polyethylene resins. The three investigated LLDPEs were: a conventional Ziegler-Natta gas phase ethylene-butene copolymer, and two solution ethylene-octene resins produced with Ziegler-Natta and single site catalysts. The octene copolymers were produced using NOVA Chemicals advanced SCLAIRTECH™ process and catalyst technologies.It was found that tear strength increases in the direction perpendicular to the highest orientation, that impact and puncture strength increase with the overall orientation and finally that the effect of orientation due to shear stresses in the die on final film properties is not significant due to rapid macromolecular relaxation before crystallization.
A Predictive Model for Dart Impact Strengths of Solution Octene LLDPE Film Resins
A predictive dart model has been developed for solution ethylene/octene linear low density polyethylene (LLDPE) resins produced using a high activity Ziegler- Natta catalyst and NOVA Chemicals’ Advanced SCLAIRTECH technology. By incorporating both polymer properties and blown film processing variables, a robust model was developed through multivariate statistical analysis. The model suggests that dart impact is a nonlinear function of polymer structure, machine direction strain rate and a corrected Deborah number. This model has also demonstrated its utility in product development at both pilot and commercial scales.
Control of Blown Film Tear Strength Anisotropy through Blending of LDPE and LLDPE
Low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) blown films differ greatly in tear strength anisotropy as LDPE generally exhibits MD>>TD tear resistance while LLDPE shows greater TD tear resistance values. In this paper, we examine the role of LLDPE/LDPE blend compositions on tear strength anisotropy and on the crystalline morphology developed during the blown film process. The crystalline morphology and orientation were measured using microscopy and infrared spectroscopy. Blending of LDPE into LLDPE suppressed the development of superstructure of LLDPE. Infrared studies suggested that both the a- and c-axes are oriented towards MD for high LDPE concentration blends. c-axis orientation gradually shifts from MD to the perpendicular plane as LDPE content decreases, accompanied with an increase of a-axis orientation in MD. Correlation between the tear resistance and the crystalline lamellae orientation is discussed.
LLDPE Blown Films Property Enhancement through Coextrusion
In this paper we investigated the performance of multilayer co-extruded LLDPE blown films. We compared five-layer films with monolayer dry-blended films and highlighted the effect of layer composition and layout on the end-use properties of the co-extruded films. Three different LLDPEs were used: a conventional Ziegler-Natta LLDPE gas phase butene copolymer, an advanced Ziegler-Natta LLDPE solution octene copolymer and a single site LLDPE solution octene copolymer. Numerous five-layer co-extruded structures comprising the single site resin and the other two Ziegler- Natta resins were produced. The coextruded structures composed of the LLDPE butene and the single site resin offer improved tear performance, relative to monolayer blended films; this was assumed due to the presence of interfacial transcrystalline layers. Also, blends of the single site LLDPE and the advanced Ziegler-Natta LLDPE octene resins within selected layers of coextruded films showed slightly enhanced tear resistance. Finally, it was found that haze is significantly reduced when the outside layers are composed of the single site resin. IntroductionA large proportion of the Linear Low Density Polyethylene (LLDPE) production is processed into thin films through the film blowing process and used as flexible packaging. An increasing number of PE film producers are equipped with multilayer blown film lines which offers more flexibility in product design and cost reduction. Consequently, it is not surprising to find in the literature several papers exploring the advantages of coextruded structures [1-4].In this work, we first compare the end-use properties of LLDPE-based coextruded blown films with monolayer blended films and then investigate the effect of layer composition and layout on film performance.
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