Neat Polyetherimide Research Articles

Effect of the Energy Director Material on the Structure and Properties of Ultrasonic Welded Lap Joints of PEI Plates with CF Fabric/PEI Prepreg

To estimate the possibility of using both low-melting TecaPEI and neat PEI films as energy directors (EDs) for ultrasonic welding (USW) of carbon fiber (CF) fabric–polyetherimide (PEI) laminates, some patterns of structure formation and mechanical properties of their lap joints were investigated by varying the process parameters. The experiment was planned by the Taguchi method with the L9 orthogonal matrix. Based on the obtained results, USW parameters were optimized accounting for maintaining the structural integrity of the joined components and improving their functional characteristics. The use of the low-melting EDTecaPEI film enabled US-welding the laminates with minimal damage to the fusion zone, and the achieved lap shear strength (LSS) values of ~7.6 MPa were low. The use of EDSolverPEI excluded thermal degradation of the components as well as damage to the fusion zone, and improved LSS values to 21 MPa. With the use of digital image correlation (DIC) and computed tomography (CT) techniques, the structural factors affecting the deformation behavior of the USW lap joints were justified. A scheme was proposed that established the relationship between structural factors and the deformation response of the USW lap joints under static tension. The TecaPEI film can be used in USW procedures when very high interlayer adhesion properties are not on demand.

PEI@MOFs thin film nanocomposite (TFN) membrane for efficient CO2 separation

Polyetherimide (PEI) membrane exhibits high CO2 selectivity while suffer from low permeance thus limiting the further application in CO2 separation. Thin film nanocomposite (TFN) membrane which contains a thin selective functional layer with nanomaterials porous fillers is a new class of high-performance membranes. In this work, a series of novel PEI@MOFs TFN membranes were prepared for efficient CO2 separation. The sub-micro scale PEI layers (about 400 nm) with four kinds of MOFs fillers including 3-dimensional MOFs nanoparticles (UiO-66 and MIL-101 (Cr)) and MOFs nanosheets (2-D CuBDC and Zn2(bim)4) were prepared by a simple spin-coating strategy. The properties and CO2 separation performance of the TFN membranes were further studied. The MOFs in PEI increased the diffusion coefficient and selectivity for CO2, at the same time, the ultra-thin functional layer maximized reducing the CO2 transport resistance. As a result, the PEI@MOFs TFN membranes exhibited high CO2 permeance as well as enhanced CO2 separation performance which close to the Robeson upper bound. The PEI@CuBDC TFN membrane exhibited CO2 permeance of 15.6 GPU (3.3 times higher than the neat PEI membrane), and the selectivity of CO2/CH4 reached 39.8 (2.2 times higher than the neat PEI membrane). In addition, the PEI@MOFs TFN membranes showed good thermal and operation stability.

Effect of Polymer Matrix on Inelastic Strain Development in PI- and PEI-Based Composites Reinforced with Short Carbon Fibers under Low-Cyclic Fatigue

Since the inelastic strain development plays an important role in the low-cycle fatigue (LCF) of High-Performance Polymers (HPPs), the goal of the research was to study the effect of an amorphous polymer matrix type on the resistance to cyclic loading for both polyimide (PI)- and polyetherimide (PEI)-based composites, identically loaded with short carbon fibers (SCFs) of various lengths, in the LCF mode. The fracture of the PI and PEI, as well as their particulate composites loaded with SCFs at an aspect ratio (AR) of 10, occurred with a significant role played by cyclic creep processes. Unlike PEI, PI was less prone to the development of creep processes, probably because of the greater rigidity of the polymer molecules. This increased the stage duration of the accumulation of scattered damage in the PI-based composites loaded with SCFs at AR = 20 and AR = 200, causing their greater cyclic durability. In the case of SCFs 2000 µm long, the length of the SCFs was comparable to the specimen thickness, causing the formation of a spatial framework of unattached SCFs at AR = 200. The higher rigidity of the PI polymer matrix provided more effective resistance to the accumulation of scattered damage with the simultaneously higher fatigue creep resistance. Under such conditions, the adhesion factor exerted a lesser effect. As shown, the fatigue life of the composites was determined both by the chemical structure of the polymer matrix and the offset yield stresses. The essential role of the cyclic damage accumulation in both neat PI and PEI, as well as their composites reinforced with SCFs, was confirmed by the results of XRD spectra analysis. The research holds the potential to solve problems related to the fatigue life monitoring of particulate polymer composites.

Cobalt Ferrite/Polyetherimide Composites as Thermally Stable Materials for Electromagnetic Interference Shielding Uses.

The progress of the automated industry has introduced many benefits in our daily life, but it also produces undesired electromagnetic interference (EMI) that distresses the end-users and functionality of electronic devices. This article develops new composites based on a polyetherimide (PEI) matrix and cobalt ferrite (CoFe2O4) nanofiller (10-50 wt%) by mixing inorganic phase in the poly(amic acid) solution, followed by film casting and controlled heating, to acquire the corresponding imide structure. The composites were designed to contain both electric and magnetic dipole sources by including highly polarizable groups (phenyls, ethers, -CN) in the PEI structure and by loading this matrix with magnetic nanoparticles, respectively. The films exhibited high thermal stability, having the temperature at which decomposition begins in the interval of 450-487 °C. Magnetic analyses indicated a saturation magnetization, coercitive force, and magnetic remanence of 27.9 emu g-1, 705 Oe, and 9.57 emu g-1, respectively, for the PEI/CoFe2O4 50 wt%. Electrical measurements evidenced an increase in the conductivity from 4.42 10-9 S/cm for the neat PEI to 1.70 10-8 S/cm for PEI/CoFe2O4 50 wt% at 1 MHz. The subglass γ- and β-relaxations, primary relaxation, and conductivity relaxation were also examined depending on the nanofiller content. These novel composites are investigated from the point of view of their EMI shielding properties, showing that they are capable of attenuating the electric and magnetic parts of electromagnetic waves.

Role of bandgap and permittivity of nanofiller in the energy storage performance of PEI-based nanocomposites

Since the promotion of the concept of nanodielectrics, the composite approach has long been considered as an effective way to improve the energy density of electrostatic capacitor films for energy storage applications. However, the selection criteria of nanofiller are blur in spite of multifarious attempts, such as Al2O3, HfO2, BaTiO3, TiO2, MnO2, MgO, etc. This paper is devoted to demonstrating the priority consideration of bandgap and permittivity in the filler selection of capacitive nanocomposite. The antagonistic effect between the bandgap and permittivity of fillers in the capacitive nanocomposite was revealed by the study of the physicochemical, dielectric, electric breakdown, and capacitive energy storage properties of polyetherimide (PEI) nanocomposites, i.e., PEI/ZrO2, PEI/SiO2, and PEI/TiO2 nanocomposites with systematically varied bandgap and permittivity. It is found that the ZrO2 nanofillers combine a wide bandgap and moderate permittivity; hence, the corresponding PEI/ZrO2 nanocomposite shows the highest discharged energy density over PEI/SiO2 and PEI/TiO2 nanocomposite. Specifically, the PEI/ZrO2 nanocomposite exhibits a maximum discharged energy density of 6.15 J/cm3 at an optimal filler content of 3 vol%, which is 57.7% higher than that of neat PEI.

Towards optimized carbon nanotubes (CNTs) reinforced polyetherimide (PEI) 3D printed structures: A comparative study on testing standards

Tailoring the properties of high-performance polymers through reinforcing will bring multifunctionality and expand their use in additive manufacturing (AM). However, machine and material-based challenges exist, eventually resulting in low-quality end products. When expensive polymers are considered, it is still challenging to tailor their properties and print them for high-quality multifunctional structures. Here, polymer composites of polyetherimide (PEI) and carbon nanotubes (CNTs) with varying CNT weight fractions are produced in filament form by melt-processing. Neat PEI, 1 wt% and 3 wt% CNTs/PEI are additively manufactured in two different raster orientations (Rectilinear and Concentric), and two most proposed testing geometries, ASTM D638 and D3039. Through effective melt-processing, CNTs-reinforced PEI filaments were achieved, printing parameters and testing protocols were discussed. As a result, ASTM D3039 showed superior coherence with filaments’ mechanical properties. Moreover, based on failure modes, ASTM D3039 provided better compatibility to AM, owing to its simple rectangular form yielding well-adhered layers.

Largely enhanced dielectric properties of polymer composites with HfO2 nanoparticles for high-temperature film capacitors

Polymer dielectrics are preferred materials for high-energy-density capacitive energy storage. In particular, high-temperature dielectrics that can withstand harsh conditions, e.g., ≥150 °C, is of crucial importance for advanced electronics and electrical power systems. Herein, high-temperature dielectric polymer composites composed of polyetherimide (PEI) matrix and hafnium oxide (HfO2) nanoparticles are presented. It is found that the incorporation of HfO2 with a moderate dielectric constant and a wide bandgap improves the dielectric constant and simultaneously reduces the high-field leakage current density of the PEI nanocomposites. As a result, the PEI/HfO2 composites exhibit superior energy storage performance to the current high-temperature engineering polymers at elevated temperatures. Specifically, the nanocomposite with 3 vol% HfO2 displays a discharged energy density of 2.82 J/cm3 at 150 °C, which is 77% higher than neat PEI. This work demonstrates the effectiveness of incorporation of the nanofiller with a medium dielectric constant into the polymer on the improvement of high-temperature capacitive properties of the polymer composites.

New mixed matrix PEI nanofiltration membrane decorated by glycidyl-POSS functionalized graphene oxide nanoplates with enhanced separation and antifouling behaviour: Heavy metal ions removal

Surface functionalization of graphene oxide (GO) nanoplates was performed by glycidyl polyhedral oligosilsesquioxane (POSS), and was used to fabrication of polyetherimide (PEI) based nanofiltration membranes by phase inversion method. The prepared membranes characterized by Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray spectrometry (EDX) and atomic force microscopy (AFM) analysis. The effect of different concentrations of glycidyl POSS-GO (PG) in membrane matrix on separation performance and antifouling property of blended membranes was investigated by contact angle measurement, pure water flux, Na2SO4, Pb(NO3)2, CrSO4 and Cu(NO3)2 rejection and flux recovery ratio. The blended PEI/PG membranes showed significant separation performance and antifouling properties compared with neat PEI and PEI/GO membranes. The highest pure water flux measured 74.77 (L/m2·h) for the blended membrane with 0.001 wt% of PG whereas it was 51.06 (L/m2·h) for the PEI/GO membrane and 17.63 (L/m2·h) for pristine membrane at 4.5 bar pressure. The blended PEI/PG membranes showed outstanding Na2SO4 and Pb(NO3)2, CrSO4, and Cu(NO3)2 rejection compared to blended PEI/GO membranes and neat PEI ones. Furthermore, the highest flux recover ratio (FRR) value was obtained (96%) for the blended [PEI/0.1 %wt PG] membrane whereas FRR was (40%) for PEI/GO and (33%) for the neat PEI membranes.

Electrically conductive high-performance thermoplastic filaments for fused filament fabrication

Conductive polyetherimide (PEI)-based filaments can fill the gap between the design and manufacturing of functional and structural components through additive manufacturing. This study systematically describes the fabrication of carbon nanotube (CNTs)-reinforced PEI filaments, complemented by a custom-built extrusion process facilitating low weight fraction of nanomaterials. Neat PEI and CNTs/PEI filaments at different CNTs fractions ranging from 0.1 to 7 wt% were fabricated. Supported by morphology analysis, the rheological percolation was found to be higher (0.25 wt% CNTs/PEI) than electrical percolation (0.1 wt% CNTs/PEI) since the system reached an electrical percolation within the formation of a continuous conductive path at lower CNTs loadings. With the 7 wt% CNTs loading, the highest electrical conductivity of CNTs/PEI filaments was reported as 2.57×10-1 S/cm. A 55% enhancement in tensile modulus was achieved when 5 wt% CNTs were introduced, but in a trade-off in elongation at break ca. 65%.

A new type of [PEI-glycidyl POSS] nanofiltration membrane with enhanced separation and antifouling performance

A new type of polyether-imide (PEI)-based nanofiltration membranes was prepared by introducing octaglycidyloxypropyl-silsesquioxane (Glycidyl POSS) into PEI matrix for heavy metals ions removal from water. The separation performance of fabricated membranes in Na2SO4, Pb(NO3)2, Ni(NO3)2 and Cu(NO3)2 removal from water as well as their flux and antifouling property was evaluated. Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) analytical method, atomic force microscope (AFM), porosity contact angle, and water content were also used in membrane characterization. The results indicated higher hydrophilicity, pure water flux (PWF) and salt rejection for PEI-POSS membranes compared to neat PEI ones. The morphological images showed good tuning porosity, finger- and spongy-like structure. The highest porosity observed for [PEI-1 wt% glycidyl POSS] with the best antifouling property. The surface roughness also decreased by incorporating of POSS into PEI matrix. The pure water flux increased from 14.3 (L/m2h) for neat PEI membrane to 36 (L/m2h) for [PEI-0.1 wt% glycidyl POSS]. Moreover, Na2SO4, Pb(NO3)2, Cu(NO3)2 and Ni(NO3)2 rejection measured 78%, 94%, 99%, 42% for [PEI-1 wt% glycidyl POSS] membrane, whereas they were 69%, 44%, 40% and 16% for the virgin PEI membrane, respectively. Results showed a good potential for [PEI-POSS] membrane in Cu and Pb ions removal beside its high PWF and antifouling ability.

Cellulose nanocrystal-polyetherimide hybrid nanofibrous interleaves for enhanced interlaminar fracture toughness of carbon fibre/epoxy composites

The effect of electrospun cellulose nanocrystals (CNCs)-polyetherimide (PEI) hybrid nanofibrous mats on Mode I and Mode II interlaminar fracture toughness of unidirectional carbon/epoxy composite laminates is demonstrated. It is shown that the CNCs reinforced PEI nanofibrillar interleaves result in a ~28% increase in Mode I initial fracture toughness values compared to neat PEI nanofibrous interleaves. Specifically, the interrelated micro- and nano-scale toughening mechanisms including carbon fibre bridging, fibre necking, fibre rupture with CNCs aggregates, and nanofibre rupture contributed to the fracture toughness improvements under Mode-I loading. Nano-scale mechanisms of shear hackles, and crack pinning by CNCs aggregates increased the Mode II fracture toughness up to ~3 kJ/m2 as a result of a 6 wt% CNCs reinforced PEI nanofibrillar mat interleave. Interleaving laminated composites with electrospun CNCs-PEI hybrid nanofibrillar mats has been demonstrated as a novel and prospective strategy to strengthen and toughen interlaminar zones of carbon/epoxy composite laminates.

Microcellular polyetherimide/graphene‐polysiloxane composite foam: intercalation structure, mechanical and thermal properties

AbstractBased on the industrialized reduced graphene oxide (RGO) product, polyetherimide (PEI)/RGO composite foam was prepared by a water‐vapor‐induced phase separation process by incorporation of polysiloxane (SI) as a compatibilizer. It was found that PEI/SI molecules were intercalated into the RGO layers through strong interfacial interaction and RGO with increased layer thickness was uniformly distributed in the PEI matrix. The composite foam possessed a homogeneous spherical‐like cell structure with narrow cell size distribution and low apparent density. In the range of 0–1 wt% RGO‐SI content, the area under the stress–strain curves increased dramatically, indicating the significantly increased toughness of the composite foam, while the tensile strength reached a maximum of 14.5 MPa at 1 wt% RGO‐SI as a result of the reinforcing effect of RGO‐SI on the foam. The addition of RGO‐SI led to a remarkable increase in Tg. Compared with neat PEI foam, the thermal degradation temperature and char yield of the composite foam clearly increased, while in the range of 0.5–3 wt% RGO‐SI a high storage modulus was maintained at high temperature, reaching about 300 MPa at 200 °C, indicating a remarkable improvement of the thermal mechanical stability of the foam. © 2018 Society of Chemical Industry

Polyetherimide-montmorillonite mixed matrix hollow fibre membranes: Effect of inorganic/organic montmorillonite on CO2/CH4 separation

Abstract Hollow fibre mixed matrix (HFMM) membranes with nano-filler embedded in polymer matrix offer an attractive route for the fabrication of high performance gas separation membranes. However, the quest to achieve high performance mixed matrix membranes remains a challenge without acquiring even filler distribution in polymer matrix. In this work, HFMM membranes comprising polyetherimide (PEI) with various inorganic and organic montmorillonite (I-MMT and O-MMT) loadings ranging from 1 to 4 wt%, were developed via phase inversion method and coated with PDMS for CO2/CH4 separation. Morphological, filler distribution, dispersion, surface topology and gas separation studies were carried out for developed hollow fibre (HF) membranes. Pure gases (CO2 and CH4) were used at varying pressure of 2–10 bars at ambient conditions. In addition, mixed gas test at CO2/CH4 composition of 50/50 v/v % was carried out for selected membranes. Upon incorporation of I-MMT, the developed mixed matrix membranes (MMMs) showed decrease in CO2/CH4 gas separation performance compared to neat PEI membrane. In contrast, the performance of asymmetric membrane was enhanced by incorporating O-MMT in PEI matrix to form MMMs. Uniform dispersion, void-free morphology and reduced surface roughness were observed for the aforementioned membranes. Furthermore, an increasing trend in ideal selectivity was observed up to 2 wt% O-MMT loading against all feed pressures. Thereafter, opposite trend was observed with increasing filler loading due to filler agglomeration. The maximum ideal selectivity achieved was 18.35 with 2 wt% loading at 4 bar pressure which is 52.2% higher than neat PEI hollow fibre membrane.

Investigation on high performance polymeric nano composite to develop transparent windshield

In this investigation, Polyetherimide (PEI) material reinforced with Graphene Oxide (GO) was prepared using Solution Casting Technique. Polyetherimide material was treated with 0.1 wt % and 0.2 wt % of graphene oxide which indicated a marginal and negligible difference in their mechanical properties compared to neat PEI. Study of Fourier Transform Infrared Spectroscopy (FTIR) analysis showed the presence of graphene oxide and polyetherimide material in the composites. Optical study using UV Spectrophotometry identified the transparency of the PEI/GO nano composites which were 41 % and 38 % for 0.1 wt % and 0.2 wt % respectively. It was noticed that there was 3 % increase in the mechanical property and 3 % decrease in the optical property of PEI/GO 0.1 wt % and PEI/GO 0.2 wt % of nano composites when they were compared.

Solid-state polyetherimide (PEI) nanofoams: the influence of the compatibility of nucleation agent on the cellular morphology

The introduction of polyhedral oligomeric silsesquioxane (POSS) particles which act as heterogeneous nucleation agent was applied to improve the cellular morphology of nanocellular polyetherimide (PEI) foams. The loading of POSS particles increases the solubility and diffusivity characteristics of gases in nanocomposite sheets by changing the distribution of the free volume and enlarging the unoccupied volume in polymer matrix. When the range of content of POSS particles is 0.2 ~ 1.0 wt. %, the range of the calculated surface tension of PEI/scCO2 (γ mix ) and radius of the critical nucleus (r*) are 30.98 ~ 28.14 mN/m, and 6.88 ~ 6.25 nm, respectively. However, the small aggregated POSS particles are favour of heterogeneous nucleation bacause the actual diameter of the aggregated POSS particles is approximate to twice r*, so the addtion of 0.5 wt. % POSS to PEI matrix presents excellent heterogeneous nucleation performance for foaming. The average cell size of 0.5 wt. % POSS/PEI nanofoams compared with neat PEI decreases from 108 to 66 nm and the cell density increses from 5.96 × 1014 to 3.34 × 1015 cells/cm3.

Effect of PVDF blending on the structure and performance of PEI hollow fiber membrane in CO2 separation process

The surface hydrophobicity of membrane is a key factor in contactor applications where the penetration of liquid into membrane pores has negative effect on the contactor performance. Therefore, different methods have been proposed for surface modification. Blending hydrophobic polymers such as surface modifying macromolecules (SMM) has been investigated in our earlier researches. In this study, the effect of polyvinylidene fluoride (PVDF) blending on the surface and bulk morphology of polyetherimide (PEI) hollow fiber membrane and its performance in membrane gas absorption process was studied. It was found that the pore size increased from 112nm to 210nm from the neat PEI membrane to the PEI membrane spun from the solution blended with 0.25wt% PVDF. At the same time, the contact angle increased from 78.3 and 84.3. Furthermore, the absorption flux of PVDF blended membrane enhanced by 13% compared to the neat PEI membrane.

Friction and wear studies of polyetherimide composites under oscillating sliding condition against steel cylinder

Tribological properties of neat polyetherimide (PEI), glass, carbon fiber, and solid lubricants filled PEI composites are presented in this article. The aim of this study was to investigate the friction and wear properties of these composites under dry oscillating sliding condition at room temperature (RT) as well as at elevated temperature (120°C). The polymer specimens were made to oscillate against steel cylinder as a counterpart. The friction and wear properties of PEI and composites were strongly influenced by the temperature. Incorporation of carbon fiber in the PEI matrix has increased the wear rate at RT, while at elevated temperature this trend was opposite. Abrasive action of carbon fibers has severely damaged the counterpart and resulted in accelerated wear of the composite at RT. Solid lubricants filled (PTFE, MoS2, graphite) along with glass fiber is beneficial in improving the friction and wear performance of the PEI composite at RT, whereas at elevated temperature wear performance was deteriorated. Tribological performance of neat PEI and glass fiber composite was similar with each other at RT. Scanning electron micrographs and optical micrographs of the worn polymer specimens and the steel cylinders was used to study the possible wear mechanisms. The present test results were also compared with data available on the reciprocating wear of PEI and composites in the literature and trends have been reported. POLYM. COMPOS., 38:48–60, 2017. © 2015 Society of Plastics Engineers

Effects of Polyvinylpyrrolidone on the Permeation and Fouling-Resistance Properties of Polyetherimide Ultrafiltration Membranes

In this study, polyetherimide (PEI) ultrafiltration (UF) membranes were fabricated by incorporating different amounts of hydrophilic polyvinylpyrrolidone (PVP) via the phase inversion technique. The PEI/PVP blended membrane showed the highest pure water flux (147.1 L m–2 h–1), water content (70.2%), and surface energy (112.1 mN/m) when the 8 wt % of PVP was blended into the base polymer PEI. This particular membrane, designated as PVP 8, also showed the lowest contact angle (56.1°), hydraulic resistance (2.2 kPa/(L m–2 h–1)), and shrinkage ratio (4.3%). The addition of PVP has reduced the tensile strength of the PEI membrane because of the decrease in rigidity. The UF experiments with the following proteins, bovine serum albumin (BSA), egg albumin (EA), pepsin, and trypsin, had experienced a decrease in protein rejection whereas permeate flux increased by increasing PVP loading. The BSA adsorption experiment revealed that the adsorbed amount of BSA on the surface of the membrane was notably decreased from 0.17 mg cm–2 of neat PEI membrane to 0.08 mg cm–2 of PVP 8. The flux recovery ratio (FRR) experiment also showed that the fouling resistance property of the membrane was enhanced with the increment of PVP.

Processing of Polyetherimide/Cloisite 30B Nanocomposite by Vibration Casting Method

Abstract Vibration casting method was developed for making polyetherimide (PEI)/Cloisite 30B nanocomposite. Towards this, a vibration casting apparatus was designed and developed. Vibration casting apparatus provided vibrational energy and heat, simultaneously. The processing parameters were established for vibration casting in terms of frequency of vibration, temperature, time and viscosity of casting mixture. Casting mixture of PEI/Cloisite 30B/N,N-dimethyl acetamide (DMAc) was made by dissolving PEI in DMAc and then mixing Cloisite 30B in this solution. The viscosity of PEI/Cloisite 30B/DMAc mixture was optimized for casting by controlling the volume fraction of PEI in DMAc. Morphology of PEI/Cloisite 30B nanocomposite was examined by wide angle X-ray diffraction, transmission electron microscopy, scanning electron microscopy and contact angle measurement. Mechanical and thermal properties of PEI/Cloisite 30B nanocomposite were also compared with that of neat PEI to ascertain the efficacy of vibration casting method.

Effects of processing conditions on foaming behaviors of polyetherimide (PEI) and PEI/polypropylene blends in microcellular injection molding process

ABSTRACTFoaming behaviors of both neat polyetherimide (PEI) and PEI/polypropylene (PP) blends were studied in this article in microcellular injection molding (Mucell) process. The study mainly focused on the comparison of two materials' foaming behaviors under different processing conditions which took a critical effect on the morphologies of foams. The results indicated that the different characteristics of PEI and PEI/PP blends, such as melt strength, gas dissolvability, and solubility, induced different nucleation ability of PEI and PEI/PP blends. The addition of PP could obviously improve the cell density and reduce the cell size. With the processing conditions changing, the morphologies of PEI/PP altered more variously, and their distribution of cell density was wider. This suggested that foaming behaviors of PEI/PP blends was more flexible to be controlled by the processing conditions than neat PEI. The effects of shot size, gas injection, and injection rate on foam morphologies were studied in detail. Shot size determined the weight reduction of samples and affected the cell density and size significantly. Gas dosing time and dosing rate determined the gas ratio which effected on foam morphologies of the PEI and PEI/PP foams. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41443.