This work evaluated the use of high power ultrasonic energy to treat corn slurry in dry corn milling ethanol plants to enhance liquefaction and saccharification for ethanol production. Corn slurry samples obtained before and after jet cooking were subjected to ultrasonic pretreatment for 20 and 40 s at amplitudes of vibration ranging from 180 to 299 microm(pp) (peak to peak amplitude in microm). The resulting samples were then exposed to enzymes (alpha-amylase and glucoamylase) to convert cornstarch into glucose. A comparison of scanning electron micrographs of raw and sonicated samples showed the development of micropores and the disruption of cell walls in corn mash. The corn particle size declined nearly 20-fold following ultrasonic treatment at high power settings. The glucose release rate from sonicated samples increased as much as threefold compared to the control group. The efficiency of ultrasound exceeded 100% in terms of energy gain from the sugar released over the ultrasonic energy supplied. Enzymatic activity was enhanced when the corn slurry was sonicated with simultaneous addition of enzymes. This finding suggests that the ultrasonic energy did not degrade or denature the enzymes during the pretreatment.

Adipic anhydride-plasticized soy protein (SP.A) was blended with poly(lactic acid) (PLA) at two concentrations (50/50 and 33/67) and was evaluated for use as a sustainable replacement for petroleum plastic in horticulture crop containers. Following the discovery that SP.A/PLA blends provide additional functions above that of petroleum plastic for this application, the present study evaluates the biodegradation behavior of these materials in soil and describes the substantial improvements in sustainability that result from the additional functions (intrinsic fertilizer and root improvement of plants) and the end-of-life option of biodegradation. After being buried in soil for designated time intervals, the residual degraded samples were analyzed to determine morphological and thermal properties at sequential stages of biodegradation. Samples were characterized by scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results indicated that there was a compatible system between SP.A and PLA in the melt. Incorporation of SP.A accelerated the biodegradation rate of this binary blend significantly compared with pure PLA. Prior to the degradation process, both the glass transition temperatures and melting temperatures of the blends containing SP.A decreased as the concentration of the soy protein increased. With increasing degradation time of the blended samples in soil, the glass transition temperatures increased in the early stages of biodegradation then decreased, a trend associated with the decrease in the molecular weight of the blends as a result of biodegradation. In addition, the thermal stability of blends increased gradually with increasing degradation time, suggesting faster biodegradation loss of the soy component of the SP.A/PLA blends. These results support the use of soy-based polymer blends for horticulture crop containers and provide data for evaluating their use as sustainable materials for other potential applications. Disciplines ABSTRACTOne of the most significant limitations to widespread industrial implementation of emerging bioplastics such as poly(lactic acid) and poly(hydroxyalkanoate) (PHA) is that they do not match the flexibility and impact resistance of petroleum-based plastics like poly(propylene) or highdensity poly(ethylene). The basic goal of this research is to identify alternative, affordable, sustainable, biodegradable materials that can replace petroleum-based polymers in a wide range of industrial applications, with an emphasis on providing a solution for increasing the flexibility of PHA to a level that makes it a superior material for bioplastic nursery-crop containers. A series of bio-based PHA/poly(amide) (PA) blends with different concentrations were mechanically melt processed using a twin-screw extruder and evaluated for physical characteristics. The effects of blending on viscoelastic properties were investigated using smallamplitude oscillatory shear flow experimen...

The extensive use of plastics in agriculture has increased the need for development and implementation of polymer materials that can degrade in soils under natural conditions. The biodegradation behavior in soil of polyhydroxyalkanoate (PHA) composites with 10 wt% distiller's dried grains with solubles (DDGS) was characterized and compared to pure PHA over 24 weeks. Injectionmolded samples were measured for degradation weight loss every 4 weeks, and the effects of degradation times on morphological, thermomechanical, and viscoelastic properties were evaluated by scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and small-amplitude oscillatory shear flow experiments. Incorporation of DDGS had a strong effect on biodegradation rate, mechanical properties, and production cost. Material weight loss increased linearly with increasing biodegradation time for both neat PHA and the PHA/DDGS 90/10 composites. Weight loss after 24 weeks was approximately six times greater for the PHA/DDGS 90/10 composites than for unaltered PHA under identical conditions. Rough surface morphology was observed in early biodegradation stages (≥8 weeks). With increasing biodegradation time, the composite surface eroded and was covered with well-defined pits that were evenly distributed, giving an areolate structure. Zero shear viscosity, T g , gelation temperature, and cold crystallization temperature of the composites decreased linearly with increasing biodegradation time. Addition of DDGS to PHA establishes mechanical and biodegradation properties that can be utilized in sustainable plastics designed to end their lifecycle as organic matter in soil. Our results provide information that will guide development of PHA composites that fulfill application requirements then degrade harmlessly in soil.