SPE Library

Inherent Flame Retardancy (FR) of copolymer compositions of Polycarbonate–Polydimethylsiloxane is presented in this paper. Properties such as limiting oxygen Index char yield surface enrichment characteristics along with UL94 performance are analyzed. Comparison is made with neat polycarbonate. Superior inherent FR coupled with good low temperature impact heat hydroaging characteristics and transparency distinguishes copolymer compositions from neat polycarbonate thereby making these compositions excellent candidates for engineering thermoplastic applications including medical and food contact applications.

Inherent Flame Retardancy (FR) of copolymer compositions of Polycarbonateƒ??Polydimethylsiloxane is presented in this paper. Properties such as limiting oxygen Index, char yield, surface enrichment characteristics along with UL94 performance are analyzed. Comparison is made with neat polycarbonate. Superior inherent FR coupled with good low temperature impact, heat, hydroaging characteristics, and transparency distinguishes copolymer compositions from neat polycarbonate, thereby making these compositions excellent candidates for engineering thermoplastic applications including medical and food contact applications.

Kneaders reactors are used for combined unitary processing in the polymer industry for devolatilization compounding or polymerization. Multiple feed ports are used in screw type reactors to allow adding multiple substrates into one product whereas one unitary operation has to get to a certain degree of completion before the next substrate can be added. We have found that even for identical substrates multiple feed ports can be advantageous to avoid specific working points where the product behavior is disadvantageous for efficient processing. Such processes require advanced design simulation tools to predict process behavior. We compare simulation results on pilot and the scale up.

Kneaders reactors are used for combined unitary processing in the polymer industry for devolatilization, compounding or polymerization. Multiple feed ports are used in screw type reactors to allow adding multiple substrates into one product whereas one unitary operation has to get to a certain degree of completion before the next substrate can be added. We have found that even for identical substrates multiple feed ports can be advantageous to avoid specific working points, where the product behavior is disadvantageous for efficient processing. Such processes require advanced design simulation tools to predict process behavior. We compare simulation results on pilot and the scale up.

This presentation discusses the latest developments in the field of nonlinear rheology of entangled polymeric liquids resulting from nearly two dozens of publications from the Polymer Dynamics Interface and Rheology Group at Akron. The essential findings are that a) entangled liquids respond to sudden startup flow elastically and undergo cohesive failure or yielding before subsequent flow is possible b) the flow field beyond the yield point is dictated by the characteristics of the yielding process that can be strongly inhomogeneous c) entangled liquids possess finite cohesion that can be overcome after flow cessation by internal elastic restoring forces.

This presentation discusses the latest developments in the field of nonlinear rheology of entangled polymeric liquids, resulting from nearly two dozens of publications from the Polymer Dynamics, Interface and Rheology Group at Akron. The essential findings are that a) entangled liquids respond to sudden startup flow elastically and undergo cohesive failure or yielding before subsequent flow is possible, b) the flow field beyond the yield point is dictated by the characteristics of the yielding process that can be strongly inhomogeneous, c) entangled liquids possess finite cohesion that can be overcome after flow cessation by internal elastic restoring forces.

Peel strength between layers in coextruded cast film is found to increase with increasing post die process time. The results suggest that adhesion is limited by the time and temperature available for bonding after new interfacial area is created during drawing. This contrasts with previous work in blown film where increases in peel strength with process time were attributed primarily to stress effects. The results from both processes however were found to collapse onto a single master curve by multiplying the peel strength by the modulus of the tie resin and dividing the process time by the relaxation time of the tie resin.

Peel strength between layers in coextruded cast film is found to increase with increasing post die process time.The results suggest that adhesion is limited by the time and temperature available for bonding after new interfacial area is created during drawing. This contrasts with previous work in blown film where increases in peel strength with process time were attributed primarily to stress effects.The results from both processes, however, were found to collapse onto a single master curve by multiplying the peel strength by the modulus of the tie resin and dividing the process time by the relaxation time of the tie resin.

Poly[butylenes succinate-co-adipate] (PBSA) layered silicate nanocomposite was prepared by melt extrusion of PBSA and organically modified montmorillonite (OMMT). Nanocomposites were prepared at a single clay loading. Before taking rheological measurements the nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Stress growth experiments were performed for both pure polymer and nanocomposite. Flow reversal experiments were conducted for nanocomposites at different predetermined rest time after cessation of forward flow. The orientation state of silicate layers were also investigated by cooling down the sample in the rheometer before and after the forward flow and then by performing X-ray in the transmission mode.

Poly[butylenes succinate-co-adipate] (PBSA) layered silicate nanocomposite was prepared by melt extrusion of PBSA and organically modified montmorillonite (OMMT). Nanocomposites were prepared at a single clay loading. Before taking rheological measurements, the nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Stress growth experiments were performed for both pure polymer and nanocomposite. Flow reversal experiments were conducted for nanocomposites at different predetermined rest time after cessation of forward flow. The orientation state of silicate layers were also investigated by cooling down the sample in the rheometer before and after the forward flow and then by performing X-ray in the transmission mode.

Hydrotalcite anionic clays were reacted with phosphonium ionic liquids containing different anions. Montmorillonite cationic clays were also reacted with the residual cation of the ILs after modification of the anionic clay. The clays were analyzed by FTIR thermal analysis EDX and X-ray diffraction in order to determine the extent and type of intercalation of the IL anions/cations at the clay interlayers. The modified cationic and anionic clays and their mixtures were then melt compounded with polylactic acid and their effects on the thermal and mechanical properties of the resulting micro- and nano-composites were investigated.

Hydrotalcite anionic clays were reacted with phosphonium ionic liquids containing different anions. Montmorillonite cationic clays were also reacted with the residual cation of the ILs after modification of the anionic clay. The clays were analyzed by FTIR, thermal analysis, EDX and X-ray diffraction in order to determine the extent and type of intercalation of the IL anions/cations at the clay interlayers. The modified cationic and anionic clays and their mixtures were then melt compounded with polylactic acid and their effects on the thermal and mechanical properties of the resulting micro- and nano-composites were investigated.

The properties of polylactic acid (PLA) may be modified by the addition of clays or the incorporation of ionic liquids (IL). The effects of clays depend on degree of polymer intercalation and the presence of clay organomodifiers. Some ionic liquids act as plasticizers and lubricants reducing glass transition temperature (Tg) and melt viscosity the effects depending on the IL structure and its polymer miscibility. This article compares the effects of different cationic or anionic clays and different ILs on the thermal hydrolytic and soil degradation of PLA as measured by molecular weight (MW) changes and relates to the structure of the additives and their degree of dispersion/dissolution in the polymer melt.

The properties of polylactic acid (PLA) may be modified by the addition of clays or the incorporation of ionic liquids (IL). The effects of clays depend on degree of polymer intercalation and the presence of clay organomodifiers. Some ionic liquids act as plasticizers and lubricants reducing glass transition temperature (Tg) and melt viscosity, the effects depending on the IL structure and its polymer miscibility. This article compares the effects of different cationic or anionic clays and different ILs on the thermal, hydrolytic and soil degradation of PLA as measured by molecular weight (MW) changes and relates to the structure of the additives and their degree of dispersion/dissolution in the polymer melt.

Since the runner-valve system (RVS) was proposed by the authors for the filling balance in multi-cavity molds its balancing capability has been proved in many experiments. However it is not practical to adjust the valve manually during the molding process. Therefore authors developed an automated RVS. A motorized actuator with a small installation area was designed and built. An experimental mold with 4 cavities was machined and the actuators were installed. In order to reliably determine the resin-arrival-time in the automated RVS a new method based on the sigmoid function approximation was developed and optimum sampling range was obtained in terms of a characteristic time. The data processing program for the approximation was designed by the LabVIEW. This work is ongoing project so that experiment using the automated RVS is going to be done.

Since the runner-valve system (RVS) was proposed by the authors for the filling balance in multi-cavity molds, its balancing capability has been proved in many experiments. However, it is not practical to adjust the valve manually during the molding process. Therefore, authors developed an automated RVS. A motorized actuator with a small installation area was designed and built. An experimental mold with 4 cavities was machined and the actuators were installed. In order to reliably determine the resin-arrival-time in the automated RVS, a new method based on the sigmoid function approximation was developed, and optimum sampling range was obtained in terms of a characteristic time. The data processing program for the approximation was designed by the LabVIEW. This work is ongoing project so that experiment using the automated RVS is going to be done.

Both batch and continuous foaming processes were employed to prepare plastic foams from polypropylene (PP) / polydimethylsiloxane (PDMS) blends. The blends were batch foamed at different saturation pressures using carbon dioxide (CO2) as the blowing agent. Ultimately the blend foams exhibited better cell morphologies and higher cell densities in comparison to those prepared from PP alone. The increased solubility of CO2 in PDMS made it as a CO2 reservoir to induce more nucleation. It was also noted that the addition of PDMS to the PP matrix generated a bi-cellular structure i.e. very small cells in the larger cell walls. In the case of extrusion foaming the addition of PDMS had a pronounced effect on both the expansion ratio and the cell density. At 5% CO2 content the maximum expansion ratio of the blend foams increased to as much as twenty-five-fold whereas the maximum expansion ratio of neat PP was below 10-fold with the same die.

Both batch and continuous foaming processes were employed to prepare plastic foams from polypropylene (PP) / polydimethylsiloxane (PDMS) blends. The blends were batch foamed at different saturation pressures using carbon dioxide (CO2) as the blowing agent. Ultimately, the blend foams exhibited better cell morphologies and higher cell densities in comparison to those prepared from PP alone. The increased solubility of CO2 in PDMS made it as a CO2 reservoir to induce more nucleation. It was also noted that the addition of PDMS to the PP matrix generated a bi-cellular structure, i.e., very small cells in the larger cell walls. In the case of extrusion foaming, the addition of PDMS had a pronounced effect on both the expansion ratio and the cell density. At 5% CO2 content, the maximum expansion ratio of the blend foams increased to as much as twenty-five-fold whereas the maximum expansion ratio of neat PP was below 10-fold with the same die.

Interlayer adhesion between tie and barrier layers in blown and cast film plays a major role in determining the performance of tie layer resins in barrier applications. In general tie-layer adhesion increases and film clarity decreases with increased maleic anhydride functionality (MAF). The tie resin employed for this investigation showed reduced adhesion to EVOH even with increased MAF. Understanding such unusual behavior is an important aspect of the structure of tie-layer resins to be used in industrial barrier packaging applications. We investigated structural factors of the tie resins using rheological measurements. It was found that dynamic shear rheological data does not provide useful information to understand tie layer performance. However extensional rheological data showed useful information to understand tie resin performance. The strain-hardening behavior of the tie-layer resin during the melt extensional process plays a major role in determining the interfacial adhesion between tie and EVOH layers and clarity regardless of a given range of MAF levels.

Interlayer adhesion between tie and barrier layers in blown and cast film plays a major role in determining the performance of tie layer resins in barrier applications. In general, tie-layer adhesion increases and film clarity decreases with increased maleic anhydride functionality (MAF). The tie resin employed for this investigation showed reduced adhesion to EVOH even with increased MAF. Understanding such unusual behavior is an important aspect of the structure of tie-layer resins to be used in industrial barrier packaging applications. We investigated structural factors of the tie resins using rheological measurements. It was found that dynamic shear rheological data does not provide useful information to understand tie layer performance. However, extensional rheological data showed useful information to understand tie resin performance. The strain-hardening behavior of the tie-layer resin during the melt extensional process plays a major role in determining the interfacial adhesion between tie and EVOH layers and clarity, regardless of a given range of MAF levels.