The poly( L -lactic acid) (PLLA) filled with nanometer calcium carbonate (nano-CaCO3) composites were prepared by means of a twin-screw extruder in the present paper. The nano-CaCO3 surface was treated with stearate. The crystalline properties of PLLA/nano-CaCO3 composites were measured using a differential scanning calorimeter, to identify the influence of the nanometer particle content on the crystalline properties. The results showed that the crystallization onset temperature, crystallization temperature and crystallization end temperature as well as the crystalline degree of the composites were obvious higher than those of the unfilled PLLA resin when the particle weight fraction (ϕf) was 1%, then they varied slightly. While the crystallization temperature interval decreased slightly. The improvement of crystallinity degree might be attributed to the heterogeneous nucleation of the nano-CaCO3 in the matrix.

Crystalline properties of poly(L-lactic acid) composites filled with nanometer calcium carbonate

Polyolefin/clay nanocomposites are mainly prepared by melt mixing, solution, and in situ polymerization approaches. Among them, the last one is more attractive because the dispersion obtained through in situ polymerization is the most efficient, particularly, in the fully exfoliated polyolefin/clay nanocomposite formation. The clay-supported coordination catalysts, i.e. Ziegler–Natta, metallocene, and late transition metal catalysts, were applied to olefins polymerization in order to produce the polyolefin/clay nanocomposites. This review presents the studies reported on the use of the clay-supported Ziegler–Natta catalysts for polymerizing the olefins, which provided that detailed examples reported in the open literature. The emphasis is placed on the production of the polyolefin/clay nanocomposites via in situ polymerization.

A review of clay-supported Ziegler–Natta catalysts for production of polyolefin/clay nanocomposites through in situ polymerization

The effect of multiple injection-moulding reprocessing of three biodegradable matrices on their mechanical properties, melt flow rate, molecular weight, phase transition temperatures and degradation temperature is presented. It has been found that, with successive reprocessing, tensile, flexural and impact strength decreased. Drop in mechanical properties has been assigned to degradation of the matrices, as corroborated by melt flow and molecular weight analysis. Although reprocessing did not significantly affect the glass transition, it diminished the melting point and degradation temperature of polymers. Results indicate that neat PLLA can be recycled for up to five times without suffering a drastic loss in mechanical and thermal properties. The aliphatic polyester Mater-Bi TF01U/095R can be recycled for up to 10 times, whilst starch-based Mater-Bi YI014U/C wastes should be destined to composting, since its recyclability is very poor. The effect of reprocessing on composites reinforced with chemithermomechanical pulp (CTMP) followed the tendencies observed for the neat matrices. Whilst CTMP-fibres behave mainly as filler in PLLA composites, reinforced thermoplastic starch-based composites presented enhanced mechanical properties and recyclability.

Recycling Ability of Biodegradable Matrices and Their Cellulose-Reinforced Composites in a Plastic Recycling Stream

The detrimental effect of cell adhesion on polymer surfaces has been a limiting factor in the medical deployment of many implants. We examined the potential to decrease cell proliferation while simultaneously increasing mechanical performance through Zn–Al layered double hydroxide (LDH) organically modified with ibuprofen dispersed in poly(L-lactic acid) (PLLA). These composites are commonly referred to as nanocomposites. The thermophysical and mechanical properties of the hybrids were studied with wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and tensile testing. The WAXD and TEM results indicated that intercalated and exfoliated nanocomposites were obtained. The storage modulus, tensile modulus, and ultimate tensile strength were improved. The LDH affected the cold crystallization and reduced the thermal stability of the neat PLLA. Smooth muscle cells were used for in vitro studies of the nanocomposites. It was found that the hybrids reduced cell proliferation, and the amount of cell reduction was related to ibuprofen release. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Poly(L-lactic acid) nanocomposites with layered double hydroxides functionalized with ibuprofen

Thermal properties of poly(l-lactide)/olive stone flour composites

Thermal properties of nanocomposites prepared of poly(L-lactide) (PLLA) and CaCO 3 applying differential scanning (DSC) calorimetry and thermogravimetry (TG) were studied. Nanocomposites were prepared by extrusion process at 170 °C. DSC measurements show that CaCO 3 has no influence on glass transition and melting point of PLLA but lowers its cold crystallization temperature. There is no difference in glass transition temperature of PLLA before and after extrusion. High temperature thermal stability of the PLLA in the composites is poorer than neat PLLA. Kinetic parameters also indicate greater reactivity of the system upon CaCO 3 addition.

Thermal Properties of Poly(L‐lactide)/Calcium Carbonate Nanocomposites

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Thermal Properties of Poly(L‐lactide)/Calcium Carbonate Nanocomposites