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Isotactic polypropylene (iPP) based nanocomposites filled with calcium carbonate nanoparticles (CaCO3) were prepared by melt mixing and their structure-properties relationships were studied. Spherical CaCO 3 coated with two different coating agents, polypropylene-maleic anhydride graft copolymer (iPP-g-MA) and fatty acids (PA), as nanoreinforced phases (C-PPMA and C-PA, respectively) were tested. The influence of nanoparticles surface treatment on the polymer/ nanofillers interfacial adhesion and on the final materials properties was also investigated. The morphological analysis has allowed defining two types of coating agents: a non-interacting agent (PA) and a coupling agent (iPP-g-MA), able to induce different iPP/nanofiller adhesion degrees. Moreover Young's modulus increases almost linearly with C-PPMA nanoparticles while a slighter improvement was recorded for iPP/C-PA nanocomposites. The iPP thermal stability is also improved by the presence of nanoparticles. Pinally, CaCO 3 drastically reduces the iPP permeability to both oxygen and carbon dioxide.

Chemical and eating quality of citrus fruit changes slowly after harvest, and quality alteration is mainly due to shrinkage, loss of firmness, excessive weight loss and decay rather than a reduction of nutritional value and taste features. Film wrapping may be a suitable means to reduce transpiration and preserve market quality provided film permeability to gases does not lead to: 1) a reduction of in-package O2 partial pressure at a point that would induce anaerobic respiration; 2) an increase of CO2 concentration to toxic levels. This experiment was carried out to study quality changes of 'Sanguinello' oranges treated or not treated with 500 mg/L imazalil (IMZ) and wrapped with continuous, macro- or micro-perforated polyolefinic films. Wrapped and no-wrapped fruit were stored at 20 degrees C and 60% RH for 20 or 30 days. In-package gas composition of the macro-perforated film showed no significant difference compared to air composition, while in-package partial pressure of CO2 and O2 ranged between 4 (continuous film) and 9.8 kPa (micro-perforated films), and 14.8 (continuous film) and 5 kPa (micro-perforated films), respectively. After 30 days of storage weight loss in fruit wrapped with the macro-perforated film was (4.3%) slightly lowerthan un-packed fruit (5%), while in all other packages weight loss never exceeded 0.7%.Quality changes were quite stable over storage in all treatments, although slight but significantly lower levels of total soluble solids and ascorbic acid were detected in micro-perforated films with the lowest degree of perforation. However, the sensory analysis denoted a remarkable decrease of firmness in un-wrapped or wrapped fruit with macro-perforated film, while a moderate build-up of off-flavour, which reduced the eating quality, developed in micro-perforated films. Decay ranged between 6 and 12% in not treated fruit, with the lowest incidence detected in un-wrapped fruit, whereas differences among the different films were not significant. No decay was detected in fruit treated with IMZ. 'Sanguinello' oranges can be stored under retail conditions for a month by the only means of film wrapping without important changes in chemical, eating and marketing quality provided fruit are treated with an effective fungicide to prevent decay and that in-package gas composition is not markedly changed with respect to air.

A novel method to enhance and control bubble nucleation in poly(l-lactic acid) (PLLA) foaming, not relying on external nucleating agents, is presented. Amorphous PLLA is annealed at temperatures close to its glass transition, to allow local alignment of polymer chains in the form of nanosized aggregates, called homogeneous crystal nuclei (HCN). PLLA containing HCN is then foamed after sorption of CO2 at 120 °C and 10 MPa. Under the chosen experimental conditions, HCN can promote growth of PLLA spherulites that can be controlled by thermal-pressure history. Foam morphology is strongly affected by the presence of HCN, which act as heterogeneous nucleation sites for bubbles. Resulting foams are characterized by a bimodal morphology, with bubbles of about 50–70 µm in diameter developed in the bulk, and much smaller cells of few µm, grown upon pre-existing crystal aggregates. The method detailed here to attain PLLA foams with tailored morphology can be exploited also for other semicrystalline polymers.

Polymer blends have been widely studied for the property improvement of commercial polymers. Most polymer blends, however, present coarse and unstable phase morphologies and poor adhesion at the interface, which is due to their immiscibility. Such problems have often been overcome with the addition of a proper compatibilizer that is able to modify the interfacial condition. In this way, it is possible to control the morphology of the material and the interphase adhesion in an appropriate manner to achieve an effective stress transfer within the blend. Compatibilization criteria and procedures, either by adding a third component (compatibilizer) or by inducing in situ chemical reactions between blend components, are reviewed. Some theoretical aspects of compatibilization processes have also been considered, giving examples of experimental consistency. The authors also report on the different compatibilizers used for several pairs of immiscible polymers with indications of their action to promote homogenization between phases.