Modification of nylon‐polyethylene blends via in situ fiber formation

Abstract

Extrusion of nylon-PE films has resulted in the successful in situ formation of high aspect ratio (possibly continuous) nylon fibers as desired. However, these fibers surprisingly provide no sigdicant reinforcement in uncompatibilized blends. While certain compatibilizing agents appear to give properties more characteristic of a fiber reinforced system, achieving higher levels of reinforcement (approaching those anticipated for fibers containing highly oriented molecules) is judged to be difficult using current methods. Based on analysis of yield stress versus modulus, the act of drawing films appears to have the greatest potential for improving reinforcement beyond the limiting case for unmodified polymers. However, the greatest challenge in realizing this potential lies in overcoming the limited extensibility allowed by nylon under normal conditions.

Morphology and Tensile Strength Prediction of in situ Microfibrillar Poly(ethylene terephthalate)/Polyethylene Blends Fabricated via Slit‐Die Extrusion‐Hot Stretching‐Quenching

“…[1][2][3][4][5][6] Unlike the well-known, in situ composite containing a liquid crystalline polymer as the reinforcing element and a thermoplastic as the matrix, in situ microfibrillar blends include two thermoplastic polymers with distinctly different melting temperatures, and the in situ generated microfibers are not made up of liquid, crystalline polymer, but thermoplastically engineered plastics, like poly(ethylene terephthalate) (PET), polycarbonate (PC), and polyamide (PA). [2][3][4][5][6][7][8][9][10][11][12] The specific process can generally be described as follows: in a first extrusion and hot-stretching step at the processing temperature of the higher-melting component, the fibrillar morphology of the higher-melting component is elaborated, then in a second step, the material containing microfibers is processed through extrusion molding or injection molding or both at the processing temperature of the lower-melting component so that the fiber structure of the dispersed phase can be maintained during this processing step. [2,5] In recent articles, [6,12,13] we reported a new in-situ, microfibrillar, reinforced blend based on polyolefins (PE and PP) and PET via slit-die extrusion-hot stretching-quenching process, yet it is essential to understand the relationship between the mechanical properties and the morphology of Summary: In situ microfibrillar poly(ethylene terephthalate) (PET)/polyethylene blends (MRB) were successfully fabricated by slit-die extrusion-hot stretching-quenching.…”

Polypropylene/Nylon‐66/Carbon Black Blends Processed at Temperatures Just Below the Nylon Melting: Anisotropy in Structure and Properties

“…That is, constant properties until a critical frequency are reached and at higher frequencies the AC conductivity increases concurringly with a decreasing permittivity. However, the value of critical frequency was 10 5 Hz, higher for the [(70PP þ 3 phr CB)/30Ny] blend. On the other hand, continuous decreasing permittivity conjugated with ascending AC conductivity as frequency was increased were observed upon measuring the same blend but perpendicular to the flow direction.…”

“…The structure is retained upon cooling, due to the LCP long relaxation time [2,3] . In thermoplastics blends, minor phase fibrillation was achieved through hot drawing [4] or the use of specially designed dies to generate high elongational deformations [5] . Minor phase fibrillation was reported in blends that were first melt mixed and then processed at temperatures below melting of this phase by means of capillary rheometers or injection molding [6,7] .…”

Essential Work of Fracture Parameters of in‐situ Microfibrillar Poly(ethylene terephthalate)/Polyethylene Blend: Influences of Blend Composition

“…[1] Its impetus comes mainly from the fact that polyolefin-based blend has a deformable dispersed phase of engineering plastics during melt processing, which can be deformed into in-situ microfibers. [2][3][4][5][6][7] The in-situ microfibers have significant reinforcement to the obtained blend whose morphology is similar with the so-called in-situ composite based on a thermoplastic and a thermotropic liquid crystalline polymer. [8,9] The engineering plastics for the microfibrillar blends consist of poly(ethylene terephthalate) (PET), polycarbonate (PC), and polyamide (PA) due to their good mechanical properties, high dimensional stability and moderate price.…”