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An annular die is used to extrude cylindrical starch foams which are then sliced to yield foam sheets suitable for cushioning protection and insulation of shipping containers. Although starch foams, as a possible replacement of petroleum-based foams, have been prepared in the past, their sensitivity to humidity remained a problem. Extensive research in the last few years has been focused on resolving the collapse of the foam at high humidity, improve the cushioning protection, and develop an economical foaming process. However, these issues are still problematic and need to be resolved before such biobased foams can gain entry into the marketplace. In this study, a BoxBehnken statistical design of experiment was used to optimize the properties of foams extruded with various additives. It was found that the density, cell structure, and the rate of water penetration of these foams were affected by the feed rates (e.g., foam composition) of the water, talc, and poly(hydroxy ether) (PHE). The use of PHE was found to be extremely effective to minimize the water sensitivity and it significantly increased the water penetration time of the foam sheets. These starch foams efficiently absorb impacts and recover its physical shape quickly to provide multiple cushion protection for moderately delicate products. POLYM. ENG. SCI., 53:857-867, 2013. © 2012 Society of Plastics Engineers, INTRODUCTION Advances in petroleum-based polymers have contributed numerous benefits to the chemical industry and currently most polymers are derived from nonrenewable resources. However, continuous depletion of crude oil resources presents [...]

Polycaprolactone (PCL) was blended in a twin-screw extruder with chemically modified thermoplastic starch (CMPS) to provide biobased and biodegradable resin composition. Reaching starch with maleic anhydride (MA) in the presence of a plasticizer and a free radical initiator provided the CMPS. The starch modification improved interfacial adhesion and processabitiy in blending with other thermoplastic polyesters. The rheological, mechanical, thermal, and morphological properties of the blends were examined. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) studies revealed that the PCL/CMPS blends are thermodynamically immiscible. However, they formed compatible blends due to the reaction of the carboxyl groups on starch backbone with hydroxyl groups of the PCL chain ends. The tensile strength and elongation decreased with increasing CMPS content, whereas the modulus increased. Dynamic viscoelastic measurements showed that the flow behavior of PCL was that of Newtonian fluid within the tested frequencies, whereas the CMPS exhibited strong shear thinning characteristics. The flow behavior of the blends varied with the CMPS content. The complex viscosity, storage, and loss moduli of the blends containing more than 40% of CMPS were higher than those of pure CMPS and PCL. In addition, the properties of CMPS to those of chemically unmodified thermoplastic starch (TPS) were compared. POLYM. ENG. SCI., 48:2126-2133, 2008. [C] 2008 Society of Plastics Engineers, INTRODUCTION Interest in biobased and biodegradable polymers is increasing, due to concerns about managing carbon emissions in a sustainable manner, and the environmental requirements for the safe and effective disposal [...]

This article concerns the utilization of maleated thermoplastic starch (MTPS) in the reactive extrusion melt-blending with poly(butylene adipate-co-terephthalate) (PBAT) in blown film applications. First, MTPS was prepared from cornstarch with glycerol (plasticizer) and maleic anhydride (MA; esterification agent). MTPS was then melt-blended with PBAT in a subsequent downstream extrusion operation. The effects of both polyester and MA contents were studied on the physicochemical parameters of melt-blends. For high polyester fractions (>60 wt%), PBAT-g-MTPS graft copolymers were obtained through transesterification reactions. They were promoted by the MA-derived acidic moieties grafted onto the starch backbone as shown by selective Soxhlet extraction experiments and FTIR analyses. At lower polyester content, no significant reaction occurred more likely due to an inversion in the phase morphology between both components. Tensile properties of PBAT-g-MTPS graft copolymer containing 70 wt% polyester were much higher as the TPS/PBAT melt-blend modified with MA. This can be explained by a finer morphology of the dispersed phase in the continuous PBAT matrix, and an increased interfacial area for the grafting reaction as attested by morphological studies. POLYM. ENG. SCI., 48:1747-1754, 2008. © 2008 Society of Plastics Engineers, INTRODUCTION Plastic packaging is now subjected to strong pressure from environmental and disposal regulations in the design of single-use disposable packaging (1), (2). Obviously, there is a need for the [...]