Phase morphology, thermomechanical, and crystallization behavior of uncompatibilized and PP-g-MAH compatibilized polypropylene/polystyrene blends

In this article, we discuss the phase morphology, thermal, mechanical, and crystallization properties of uncompatibilized and compatibilized polypropylene/polystyrene (PP/PS) blends. It is observed that the Young\u27s modulus increases, but other mechanical properties such as tensile strength, flexural strength, elongation at break, and impact strength decrease by blending PS to PP. The tensile strength and Young\u27s modulus of PP/PS blends were compared with various theoretical models. The thermal stability, melting, and crystallization temperatures and percentage crystallinity of semicrystalline PP in the blends were marginally decreased by the addition of amorphous PS. The presence of maleic anhydride-grafted polypropylene (compatibilizer) increases the phase stability of 90/10 and 80/20 blends by preventing the coalescence. Hence, finer and more uniform droplets of PS dispersed phases are observed. The compatibilizer induced some improvement in impact strength for the blends with PP matrix phase, however fluctuations in modulus, strength and ductility were observed with respect to the uncompatibilized blend. The thermal stability was not much affected by the addition of the compatibilizer for the PP rich blends but shows some decrease in the thermal stability of the blends, where PS forms the matrix. On the other hand, the % crystallinity was increased by the addition of compatibilizer, irrespective of the blend concentration

Thermal degradation and crystallization characteristics of multiphase polymer systems with and without compatibilizer

Effects of blend composition and compatibilizer concentration on the thermal degradation and crystallization characteristics of polyolefin blends are reported. Phase morphology and therefore, blend composition played a crucial role in the thermal degradation behaviour of the blends. Although compatibilization significantly improved the thermal stability of the blends, melting and crystallization parameters of the polymers were only marginally affected. Compatibilized blends with co-continuous morphology exhibited a type of “co-degradation” and “co-crystallization”

Miscibility, UV resistance, thermal degradation, and mechanical properties of PMMA/SAN blends and their composites with MWCNTs

Poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) (PMMA/SAN) blends, with varying concentrations, were prepared by melt-mixing technique. The miscibility is ensured by fixing the acrylonitrile (AN) content of styrene acrylonitrile (SAN) as 25% by weight. The blends were transparent as well. The Fourier transform infrared spectroscopic (FTIR) studies did not reveal any specific interactions, supporting the well accepted \u27copolymer repulsion effect\u27 as the driving mechanism for miscibility. Addition of SAN increased the stability of PMMA towards ultraviolet (UV) radiations and thermal degradation. Incorporation of even 0.05% by weight of multi-walled carbon nanotubes (MWCNTs) significantly improved the UV absorbance and thermal stability. Moreover, the composites exhibited good strength and modulus. However, at higher concentrations of MWCNTs (0.5 and 1% by weight) the thermo-mechanical properties experienced deterioration, mainly due to the agglomeration of MWCNTs. It was observed that composites with 0.05% by weight of finely dispersed and well distributed MWCNTs provided excellent protection in most extreme climatic conditions. Thus, PMMA/SAN/MWCNTs composites can act as excellent light screens and may be useful, as cost-effective UV absorbers, in the outdoor applications

Development of hybrid composites for automotive applications: effect of addition of SEBS on the morphology, mechanical, viscoelastic, crystallization and thermal degradation properties of PP/PS-xGnP composites

In this article, we report on a simple and cost effective approach for the development of light-weight, super-tough and stiff material for automotive applications. Nanocomposites based on PP/PS blend and exfoliated graphene nanoplatelets (xGnP) were prepared with and without SEBS. Mechanical, crystallization and thermal degradation properties were determined and correlated with phase morphology. The addition of xGnP to PP/PS blend increased the tensile modulus at the expense of toughness. The presence of xGnP increased the enthalpy of crystallization and enthalpy of fusion of PP in the blends, without affecting segmental mobility and thermal stability. Addition of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) improved the toughness of PP/PS blends, but decreased the stiffness. The incorporation of xGnP into this ternary blend generated a super-tough material with improved stiffness and tensile elongation, suitable for automotive applications. It is observed that the presence of SEBS diminished the tendency of agglomeration of xGnP and their unfavorable interactions with thermoplastics, which in turn reduced the internal friction in the matrix

The role of SEBS in tailoring the interface between the polymer matrix and exfoliated graphene nanoplatelets in hybrid composites

Nanocomposites of polypropylene (PP) and polypropylene/styrene-(ethylene-co-butylene)-styrene triblock copolymer (SEBS) blends with exfoliated graphene nanoplatelets (xGnP) were prepared by melt-mixing method. The incorporation of xGnP increased the stiffness and crystallinity of PP at the expense of toughness and the molecular mobility. The effect of addition of SEBS on the mechanical, viscoelastic, thermal degradation and crystallization properties of PP/xGnP composites was studied. The addition of SEBS into PP transformed the phase structure and distribution of xGnP in the PP matrix. SEM micrographs revealed that SEBS polymer chains formed a coating over the graphene nanoplatelets, which strengthened the interface between the filler and the matrix, and improved the dispersion and distribution of the filler throughout the matrix

Tempo de cobertura com agrotextil em híbridos de tomateiro de crescimento determinado em condições de cultivo protegido

O cultivo de hortaliças em sistema protegido no Brasil é recente, apesar de existirem alguns trabalhos registrados já na décadade 60. Na busca de novos materiais para utilização em cobertura de plantas na agricultura, o agrotextil de polipropileno é um material que pode ser colocado diretamente sobre a planta inclusive sem necessidade de uso de suporte. Desta forma, objetivou-se verificar as interferências do túnel de agrotêxtil sobre dois híbridos de tomate de crescimento determinado em ambiente protegido. O trabalho foi desenvolvido no município de Ilha Solteira (SP), em solo Argissolo Vermelho estrófico. O delineamento foi em blocos casualizados, disposto no esquema de parcelas subdivididas, com cinco repetições. Os tratamentos foram constituídos pela combinação de dois híbridos (Malinta e AP 529), e diferentes tempos de cobertura das plantas de tomate com agrotêxtil (0, 14, 22, 29 e 39 dias), sob ambiente protegido. Foram realizadas as seguintes avaliações: temperaturas máximas e mínimas, luminosidade, massa média de frutos, número de frutos por planta, produção de frutos total, comercial e furados e distribuição da produção de frutos nas colheitas. Verificou-se que a cobertura de agrotextil induziu um aumento na temperatura máxima e redução na luminosidade próxima às plantas, porém, não influenciou o número de frutos por planta e a produtividade total e comercial de frutos. O aumento no tempo de cobertura reduziu a massa média do fruto, a produção de frutos furados pela broca e o número de pulverizações efetuadas. O maior tempo de cobertura retardou a colheita dos frutos, porem, não alterou o pico da colheita dos frutos. O híbrido Malinta produziu maior número e com menor massa média de frutos que o híbrido AP 529

Toughened PS/LDPE/SEBS/xGnP ternary composites: morphology, mechanical and viscoelastic properties

In this work, we have developed super tough ternary polymer blends and composites composed of polystyrene (PS), low-density polyethylene (LDPE), polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) and exfoliated graphene nanoplatelets (xGnP). A 50/50 composition of PS and LDPE was selected for making the binary blend. The addition of xGnP in the binary blend reduces the tensile strength, elongation at break and tensile toughness considerably due to the unfavorable interactions existing between PS, LDPE, and xGnP. On the other hand, the mechanical properties of PS/LDPE binary blends are considerably improved by the addition of SEBS at the expense of modulus. The best results were obtained for a 33/33/33 (PS/LDPE/SEBS) composition. Further, different concentrations of xGnP were incorporated in the ternary blend with 33/33/33 composition. Interestingly, the composites show a significant improvement in mechanical properties especially for 2.91 wt% xGnP modified ternary blend. The DMA studies revealed that the stress with in the ternary composites are minimum when compared with binary blends and their composites. The variation in the phase morphology of the binary blends by the addition of SEBS and xGnP is responsible for the dramatic changes in mechanical and viscoelastic properties. This study validates large improvement in mechanical properties of the PS/LDPE polymer blends by the careful selection of SEBS and xGnP. Keywords: Polystyrene, Low-density polyethylene, Polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene, Exfoliated graphene nanoplatelets, Toughened plastic

Tailoring of interface of polypropylene/polystyrene/carbon nanofibre composites by polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene

Mechanical and physical properties of polypropylene (PP)/polystyrene (PS) blend, PP/PS/polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) ternary blend and their composites with carbon nanofibers (CNF) were investigated. Composites of ternary blend exhibited superior properties compared to those of binary blends. Mechanical performance of nanocomposites was intimately related to their phase morphology. PP/PS/SEBS/0.1 wt% CNF hybrid composites exhibited excellent impact strength (Four-fold increase compared to PP/PS blend) and ductility (12-fold increase in elongation at break, with respect to PP/PS blend). Moreover, these composites displayed good tensile strength and modulus (15% increase in Young\u27s modulus, compared to PP/PS/SEBS blend) and are suitable for various end-use applications including automobile applications. Although crystallinity of PP phase is decreased by the incorporation of CNF, thermal stability of the composites remained almost unaffected. Contact angle measurements revealed that ternary composites exhibited maximum hydrophobicity