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This study investigated the effect of polylactic acid (PLA) on the mechanical properties and biodegradability of a ternary blend comprising of thermoplastic starch (TPS), Polybutylene adipate terephthalate (PBAT) and PLA. The binary blend (TPS/PBAT) and ternary blend (TPS/PBAT/PLA) with various contents of PLA were prepared through a twin-screw compounding using an intensive mixing screw design. In order to observe the microstructure in blends, the SEM observation revealed the two types of morphology in the blends including (1) some TPS domain that still remained immiscible in all blends and (2) the partially compatible of binary and ternary blends. For the mechanical properties of the blends, the addition of the PLA component led to an improvement of the tensile strength and modulus. For the simple soil burial test, it found that binary film was fully disintegrated within one month, whereas the ternary blend films were also broken down but still remained in small pieces of fragile films. Finally, it can be suggested that the presence of TPS brought to the biodegradation of blends in soil burial test, while incorporating with PLA led to retardation in degradation rate.

This study was aimed to develop conductive packaging for ohmic heating. Polypropylene (PP) was mixed with conductive material (CM) in the ratios of 70:30 (CM30), 75:25 (CM25), and 80:20 (CM20) (w/w), then the conductive bottles were developed using extrusion blow molding process. The bottles were suspended in different sodium sulfate (Na2SO4) solutions (0.2, 0.3, and 0.5% w/w) as a transmitting current medium for ohmic heating and heated for 8 min. The CM30 and CM 25 had the highest electrical conductivity compared to the CM20, however the CM20 exhibited best processability, hence it was selected to be used for ohmic heating of orange juice. Different concentrations of Na2SO4 solutions had the effects on ohmic heating. The CM20 bottle suspended in 0.2% Na2SO4 solution resulted in the most uniform heating and suitable for ohmic processing of orange juice. The new conductive bottles developed could potentially be used for beverage processing by ohmic heating.

Poly(lactic) acid (PLA) is bioplastic produced from corn starch; its brittleness limits the use of PLA in many applications. Biaxial stretching is one approach adopted by film manufacturers to enhance the properties of plastics such as polypropylene (PP). This study aims to produce biaxially-oriented PLA films which had been toughened with 1-10% core-shell rubber (CSR). Differential scanning caloriemetry (DSC) results indicated that all biaxially-stretched neat PLA and the PLA/CSR films possessed nearly 20% greater crystallinity than the as-cast film.The yield stress of the biaxially-stretched films were higher than that of the unstretched films in both machine (MD) and transverse (TD) directions. After biaxial stretching, the elongation at break of the stretched films was still much higher than that of the unstretched ones. The tear resistance was highest in the film with 5 wt% CSR, it became higher after biaxial stretching. The water vapor permeation (WVP) was also minimum in the film with 5 wt% CSR. The biaxially-stretched films had lower WVP than the unstretched ones due to the enhanced crystallization and chain orientation in the stretched films.

In this article, the effect of montmorillonite (MMT) concentration on the nucleation of polypropylene (PP) was investigated. The PP/MMT nanocomposites containing various content of MMT (0.075-3.0 wt%) were prepared by a melt blending process using an internal mixer, followed by compression molding into sheets. The nucleation effect of MMT was characterized by X-ray diffraction (XRD), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) techniques. XRD results indicated that the PP nanocomposites loaded with less than 1.5 wt% of MMT formed an exfoliated structure. DSC results showed that the crystallization temperature (Tc) of PP/MMT nanocomposites were higher than that of neat PP. Tc also increased with increasing MMT content, indicating that MMT was effective in nucleating PP crystal. WAXD patterns revealed that the addition of MMT did not affect the crystal structure of PP. Mechanical property tests showed that the tensile and impact strengths of the PP/MMT nanocomposites were better than those of neat PP when the MMT content was lower than 1.5 wt%.

This study investigated the effect of the organic phthalocyanine blue and inorganic ultramarine blue pigments on nucleation of polypropylene (PP). The PP/pigment pellets containing various concentrations of each pigment (0.0001-0.1 wt %) were prepared by a melt blending process using a single-screw extruder, followed by fabricating into thin sheets using a single-screw plastic sheet extruder. The nucleation effects of both pigments were characterized by wide angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) techniques. The WAXD patterns revealed that the addition of phthalocyanine blue or ultramarine blue did not affect the crystal structure of PP. The DSC results indicated that both pigments were able to nucleate PP, where the organic phthalocyanine blue pigment was a very efficient nucleating agent, increasing the crystallization temperature of PP by 15oC. The results of tensile and optical tests showed that the tensile strength and clarity of PP were improved with phathalocyanine blue addition.

This study investigated the biaxially drawn behavior of polypropylene (PP) containing different crystalline structure in between of either α-monoclinic or β-hexagonal crystal form or a combination of both. The precursor sheet with α-crystalline PP was prepared from neat resin using the sheet extrusion process. The high content of β-crystalline phase (K-value of about 84%) was developed in the polypropylene sheet using a proprietary type and concentration of β-crystal nucleator. Biaxial film stretching was carried out using a laboratory stretching machine at the temperature of 145°C. Stretching speed and stretch ratio were kept relatively constant at 400 %/sec and 5.5 x 5.5, respectively. β-PP sample demonstrated a distinct biaxially drawn behavior as compared to that of the neat-PP sample, in particular, biaxial yield stress of neat PP (α-PP) was 3.55 MPa, where a much lower biaxial yield stress value was apparent for β-PP (~1.69 MPa). Interestingly, the total calculated area under stretching curves of the β-nucleated PP sample was about 34.8 % lower than that of the neat PP sample. These findings indicate the less energy required for stretching process of β-nucleated PP. Moreover, the drawn β-PP films also showed comparable mechanical properties to the α-PP sample as well as a good optical property, evidenced by low haze values of <1% which was close to that for the normal BOPP films.

This study focused on investigating the Nd:YAG laser perforation process of several common plastic films including biaxially-oriented polypropylene (BOPP), biaxially-oriented polyethylene terephthalate (BOPET) and low density polyethylene (LDPE) films. Films were perforated under various pulse energies of 50, 150 and 250 mJ and with pulse duration of ~10 ns and pulse repetition of 1 Hz. It was found that, BOPP, BOPET and LDPE films could be perforated using our developed Nd:YAG laser perforating system. Perforation width or diameters of all films increased with increasing pulse energies. Observed perforations were different among the three film types. For instance, at the pulse energy of 150 mJ, average microperforation diameters of BOPP, BOPET, and LDPE were 51.9, 57.5, and 31.0 microns, respectively. Overall results clearly demonstrated that a Nd:YAG laser perforation process used in this study was effective in developing breathable packaging films with tailored oxygen permeation property. Commercial BOPP films containing 200-1,400 micro-perforations/m2 (average perforation diameter of  50 µm) showed a significant improvement in oxygen transmission rates (OTR) of 25-700% over that of the regular BOPP. Very high OTR films of 16,000 cc/m2.day could be effectively produced for the micro-perforated BOPP, where OTR values of close to 20,000 cc/m2.day was obtainable in the case of BOPET films.

The objective of this study is to correlate the crystal structure with material and processing parameters, in particular -nucleating agent and degree of supercooling. The selected -nucleating agent used in this study was “Quinacridone pigment, E3B” with concentration varied from 1 to 100 ppm. The degree of supercooling during sheet extrusion process was controlled by chill roll temperatures in a range of 60 to 115oC. Crystal structures in neat PP and PP-E3B samples were characterized using WAXD and DSC techniques. The selected PP-E3B, with optimum concentration of 5 ppm, was fabricated into sheets using chill roll temperatures of 60, 70, 80, 90, 100, 110 and 115oC; these sheets had -crystal content (K-value) of about 0.099, 0.214, 0.341, 0.430, 0.651, 0.754 and 0.892, respectively. The melting characteristics and physical properties of the nucleated iPP were also dependent upon -crystal content. Finally, it could be concluded that the development of -crystal structure was highly influenced by the concentration of nucleating agent and processing conditions during sheet extrusion.