Study of the rheological properties of melts of polypropylene and poly(butylene terephthalate) blends

Abstract

The viscosity properties of melts of fibre-forming polypropylene (PP) and poly(butylene terephthalate) blends were investigated in the entire range of ratios at different stresses and shear rate gradients at 230-250°C. It was shown that melts of fibre-forming PP and PBT blends are weakly crosslinked systems. The effect of the mass ratio of PP and PBT on the apparent activation energy of viscous flow of melts of the blends was investigated at different shear stresses and shear rate gradients. It was hypothesized that this blend can be assigned to the group of limitedly compatible systems. The probability of compatibility of the polymers in the melt appears when up to 20% PBT is incorporated in the PP. The blends are not compatible for the remaining ratios of polymers in the investigated system.We know that the performance properties of articles made of polymer blends are determined to a significant degree by the mutual dispersion of the components. The complete (thermodynamic) compatibility of film-and fibre-forming polymers in a melt is a somewhat rare exception. The possibility of spontaneous molecular mixing of different macromolecules (their mutual solubility) is due to both the enthalpic and the entropic aspects of the process of attaining the equilibrium state [1].The important amount of accumulated experimental and theoretical data indicates the validity of the statement that the relaxation (and consequently structural-mechanical) characteristics of polymers in the viscous-flow and solid states are somewhat close. This is due to the cooperativity of deformation processes on the supramolecular level [2, 3], which substantiates the approach to predicting the possibility of combining different linear polymers in the solid state based on the results of studying the temperature dependence of the viscosity of melts of polymer blends in the entire range of ratios of components (naturally, outside of the binodal phase boundary). It is evident that the compatibility (mutual solubility) of polymers both in the solid state and in melts is determined by the same thermodynamic factors as the mutual solubility of low-molecular-weight compounds, but their primary structure and the flexibility of linear macromolecules must be taken into consideration [3], since molecular mixing can only be realized on the segmental level.According to the FloryScott concept [4], the thermodynamic compatibility of polymers in the solid state can be predicted with some degree of probability by comparing the solubility parameters of the components of the blend: (δ s.1 δ s.1 ) = = Δδ ≤ 1.5 (cal⋅cm -3 ) 0.5 ≡ 3075 (J⋅m -3 ) 0.5 , where the solubility parameters δ p.i of the miscible polymers can be validly estimated with the Askadskii method [5]:, 1

Investigation of the Characteristics of Elasticised Woven Fabric by Using PBT Filament Yarns

“…According to the literature survey, researches with respect to PBT are mainly focused on nonwoven production, particularly for filtration purposes [5][6][7][8][9][10][11][12][13][14][15]. Besides, an artificial neural network model was developed to predict the seam strength and elongation at break values and cotton, core-spun, and PBT sewing yarns have been used for experimental.…”

Polibütilen Tereftalat Liflerine Genel Bakış

“…Polimer karışımları ile ilgili çeşitli çalışmalar yapılmıştır. Kovaleva ve arkadaşları [17] lif oluşturma işlemlerinde, polipropilen (PP) ve PBT karışımlarının özelliklerini incelemiştir. PP ve PBT karışımlarının limitli karışabilir sistemler olduğu belirtilmektedir.…”

“…Karışımdaki PBT içeriği arttıkça sistem uyumsuz hale gelmektedir. Lif çekimi sırasında PBT liflerine az miktarlarda PP eklenmesi ile lif oluşturulabilmektedir [17].…”

“…Poliester ştapel, tops ve iplikler soğuk su, ardından sıcak su ile durulama yapılarak uzaklaştırılabilen suda-çözünür preparatlar içermektedir [17]. Lif üzerinde bulunan yumuşatma maddeleri, proses yardımcıları veya bobin yağları gibi kimyasallar düzgün bir biçimde giderilemezlerse, lifler üzerinde depolanmakta ve daha sonra ürünlerde lekelenmelere neden olmaktadır.…”

“…Lif üzerinde bulunan yumuşatma maddeleri, proses yardımcıları veya bobin yağları gibi kimyasallar düzgün bir biçimde giderilemezlerse, lifler üzerinde depolanmakta ve daha sonra ürünlerde lekelenmelere neden olmaktadır. Bu nedenle yıkama banyosunda non-iyonik deterjanların kullanılması gerekmektedir [17].…”