The concentration of benzoic acid was found to exercise efficient control over the formation of either MIL-101(Cr) or MIL-88B(Cr) under otherwise similar hydrothermal synthetic conditions.

In this work, sericite mica was initially modified with a multi-step procedure and the novel composites of polyimide (PI) with the organophilic sericite mica were subsequently synthesized via in situ polymerization technique. XRD patterns revealed d 002 -spacing of clay was expanded from 0.99 to 2.77 nm. TEM photographs indicated majority of the organoclay exhibited an exfoliated morphology structure in composites with 5 wt% filler loading. Several critical properties of composites such as thermal stability, mechanical property, and storage modulus were tremendously enhanced with the increasing organoclay loading. Especially, the glass transition temperature of composites with 7 wt% organoclay addition revealed a 72 C increment compared with pristine PI, indicating greater improvement than the reported literature values. POLYM. COMPOS.,

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Polyamide 6-66 (PA6-66)-montmorillonite (MMT)-nanosilica (NS) nanocomposite films were fabricated through a cast film process and then biaxially stretched on a laboratory stretcher. Uniaxial or biaxial stretching induced the elongated conformation of MMT and NS. The b axis of the α crystals and the amorphous phase were revealed to align along the machine direction (MD) after stretching, with the uniaxial orientation playing a more significant role. Furthermore, the crystallinity of PA6-66 stretching increased with the stretching ratio. Uniaxial stretching gave rise to a significantly enhanced tensile strength along the MD, whereas it slightly decreased the mechanical properties along the transverse direction (TD). In contrast, the films subjected to biaxial stretching exhibited more balanced mechanical properties. Uniaxial and biaxial stretching led to decreased transmittance and increased haze in the PA6-66-MMT-NS films; this could have been due to the elongated nanostructure of the two nanofillers, which inhibited the transmission and facilitated the scattering of visible light. The thermal shrinkage of the films increased with increasing stretching ratio, and the biaxially oriented films presented nearly equal shrinkage in the MD and TD. The addition of nanofillers decreased the shrinkage attributed to the mobility inhibition of the polymer chains during heating.

A series of polyimide(PI) adhesives were synthesized from 2,2'-Bis [4-(4-aminophenoxy)phenyl] propane(BAPP), 4,4'-Diaminodiphenylmethane (MDA) and 3,3',4,4'-Benzophenonetetracarboxylic acid dianhydride (BTDA) via a two-step process. PI adhesives with different BAPP content were characterized in regard to their structure, thermal stability, mechanical properties and adhesive performance. Results showed that these PIs had excellent thermal stability, whose glass transition temperature (Tg) were around 300 C. While, superior dynamic mechanical behavior was observed, and the maximum loss factor declined with the increase of BAPP content. Single-lap shear strength of over 15.58 MPa at room temperature was obtained, and it remained high even at the temperature of 350 C. Factors that could affect bonding strength of these PI adhesives such as molar ratio of the diamine monomers, surface roughness of adherends and curing processes were investigated.