Journal of Plastic Film & Sheeting

There is a delicate balance between processability, mechanical properties, and seal performance when LDPE/LLDPE blends are used. Choosing the right blend proportion is sometimes a very difficult job, and it can consume much resin and time. An easy-to-use selector that can run in most spreadsheet programs was devised based on the design of experiment (DOE) approach. This selector is intended to reduce the time and material needed to achieve a given set of properties.

A technique that involves design of experiments was developed to generate a set of equations that predicts processing, mechanical and shrink properties of HDPE/LDPE/LLDPE blends. The results are presented in an easy-to-use spreadsheet that can be used even in pocket computers.

The North American market for biodegradable plastics in 2005 was estimated to be around 60 million pounds (27 kt). Starch-based polymer blends were expected to account for 30 million pounds (14 kt) with significantly lower growth rates than other biodegradable polymers such as polyesters. The main hurdle in the growth of starch-based products is the thermodynamic immiscibility and non-wetting of starch with other polymers which leads to serious deterioration of mechanical properties at >25–30 wt% starch. Higher amounts of starch in the blends entail adding suitable functional groups on starch and other polymers in the blend to make them more compatible. The primary challenge is to develop fast reaction chemistries that can be transformed into viable processes and integrated into existing process lines with economically viable formulations. This article briefly reviews some of the most promising chemistries available for the reactive extrusion of starch-based polymer blends (biodegradable/non-biodegradable).

Thermic greenhouse covers are plastic films that block infrared (7–14 mm) radiation to reduce the risk of frost when the greenhouse is not heated and to reduce the energy consumption when a heating system is used. The standard mineral fillers (calcined kaolin), which have been normally used to increase the IR opacity of LDPE and other greenhouse films, accelerate the photodegradation of the film as well as moderately increase the haze and diminish the light transmission. In this work, we present a new family of mineral fillers that do not accelerate photodegradation, do not lower the light transmission, and give low or high haze, depending on what is required. With these mineral fillers, the optical properties can be optimized and the IR effectiveness can be reached, thus giving a new generation of ultrathermic films (UT). Using them as greenhouse covers, heat energy savings between 5% and 10% can be achieved.