ABSTRACT:The compatibilizing effect of the triblock copolymer poly(styrene-b-butadiene-b-styrene) (SBS) on the morphology and mechanical properties of immiscible polypropylene/polystyrene (PP/PS) blends were studied. Blends with three different weight ratios of PP and PS were prepared and three different concentrations of SBS were used for investigations of its compatibilizing effects. Scanning electron microscopy (SEM) showed that SBS reduced the diameter of the PS-dispersed particles as well as improved the adhesion between the matrix and the dispersed phase. Transmission electron microscopy (TEM) revealed that in the PP matrix dispersed particles were complex ''honeycomblike'' aggregates of PS particles enveloped and joined together with the SBS compatibilizer. Wide-angle X-ray diffraction (WAXD) analysis showed that the degree of crystallinity of PP/PS/SBS slightly exceeded the values given by the addition rule. At the same time, addition of SBS to pure PP and to PP/PS blends changed the orientation parameters A 110 and C significantly, indicating an obvious SBS influence on the crystallization process in the PP matrix. SBS interactions with PP and PS influenced the mechanical properties of the compatibilized PP/PS/SBS blends. Addition of SBS decreased the yield stress and the Young's modulus and improved the elongation at yield as well as the notched impact strength in comparison to the binary PP/PS blends. Some theoretical models for the determination of the Young's modulus of binary PP/PS blends were used for comparison with the experimental results. The experimental line was closest to the series model line.

ABSTRACT:Compatibilizing effects of styrene/rubber block copolymers poly(styrene-bbutadiene-b-styrene) (SBS), poly(styrene-b-ethylene-co-propylene) (SEP), and two types of poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS), which differ in their molecular weights on morphology and selected mechanical properties of immiscible polypropylene/polystyrene (PP/PS) 70/30 blend were investigated. Three different concentrations of styrene/rubber block copolymers were used (2.5, 5, and 10 wt %). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the phase morphology of blends. The SEM analysis revealed that the size of the dispersed particles decreases as the content of the compatibilizer increases. Reduction of the dispersed particles sizes of blends compatibilized with SEP, SBS, and low-molecular weight SEBS agrees well with the theoretical predictions based on interaction energy densities determined by the binary interaction model of Paul and Barlow. The SEM analysis confirmed improved interfacial adhesion between matrix and dispersed phase. The TEM micrographs showed that SBS, SEP, and low-molecular weight SEBS enveloped and joined pure PS particles into complex dispersed aggregates. Bimodal particle size distribution was observed in the case of SEP and lowmolecular weight SEBS addition. Notched impact strength (a k ), elongation at yield ( y ), and Young's modulus (E) were measured as a function of weight percent of different types of styrene/rubber block copolymers. The a k and y were improved whereas E gradually decreased with increasing amount of the compatibilizer. The a k was improved significantly by the addition of SEP. It was found that the compatibilizing efficiency of block copolymer used is strongly dependent on the chemical structure of rubber block, molecular weight of block copolymer molecule, and its concentration. The SEP diblock copolymer proved to be a superior compatibilizer over SBS and SEBS triblock copolymers. Low-molecular weight SEBS appeared to be a more efficient compatibilizer in PP/PS blend than high-molecular weight SEBS.

No abstract

No abstract

Purpose -The purpose of this paper is to assess whether environmental management systems (EMS) according to ISO 14001 requirements have contributed to the implementation and adoption of new technologies and to the issues related to technology performance in industrial enterprises. Design/methodology/approach -The research is based on the questionnaire survey conducted on a sample of ISO 14001 certified Slovene manufacturing companies. Findings -The results revealed that ISO 14001 certified manufacturing companies still mostly used the combination of partly adopted and partly modified technologies in order to reduce environmental impacts. ISO 14001 was considered as a very useful tool for the promotion of technological modernisation. It was shown also that ISO 14001 standard can play a significant role as a support tool for the acceleration of technological innovation activities regardless of the origin of the technology.Research limitations/implications -The research surveyed only industrial ISO 14001 certified enterprises in the Republic of Slovenia. Differences among industrial branches exist as well as among small, medium and large enterprises. These facts must be further studied. Practical implications -ISO 14001 certification proved to be an important driver for technological modernisation in industrial practice. Some environmental indicators are still underestimated or nonsufficiently included into firms' environmental policies and must be certainly improved. Since adoption of new technologies and EMS were rarely covered together the findings are interesting for wider community. Originality/value -The paper covers a subject on how adoption of ISO 14001 influences technological changes and related activities. Not many information and in-depth case studies have been available until now.