A New Method for Continuous Solid‐State Biaxial Orientation of Polymeric Films

Abstract

A new laboratory-scale method for continuous solidstate biaxial deformation of polymer materials is introduced. The tabletop biaxial drawing tool utilizes a heated metal disc-like triangular mandrel, which allows for continuous solid-state biaxial deformation of a precursor polymer tube with a controlled drawing speed. The new biaxial drawing tool features two independent heating zones. The main mandrel sets the biaxial drawing temperature. In addition, directly after the mandrel, an annealing unit with a separate heating zone is added for better control of important process parameters, such as post-relaxation and strain-induced crystallization. As such, the new biaxial drawing tool is a tabletop analogue of the industrial triple-bubble process. Finally, a detailed theoretical model describing the deformation field and the forces needed to perform biaxial drawing as a function of the biaxial drawing ratio is presented and compared to experimental values, using isotactic polypropylene as model material.

Flexible Strain Sensors with Enhanced Sensing Performance Prepared from Biaxially Stretched Carbon Nanotube/Thermoplastic Polyurethane Nanocomposites

“…The results showed that the nanofillers in HDPE matrix deagglomerated and reoriented during the biaxial stretching; thus, the barrier and tensile properties of biaxially stretched HDPE/GNP/CB and HDPE/GNP/CNT nanocomposites were significantly increased. Biaxial stretching is an efficient film processing technology for polymers and their composites, and it is also a deformation mode in some common processing approaches like thermoforming and blown film extrusion and is therefore of interest in material and product development . In the area of flexible strain sensor development, only a few studies have assessed how biaxial stretching process affecting the performance of the sensors, hence the need for the current work. − …”

Flexible strain sensors with high sensitivity and large working range prepared from biaxially stretched carbon nanotubes/polyolefin elastomer nanocomposites

“…However, these methods are disadvantageous in terms of low efficiency, high cost, and difficult industrial production. Biaxial stretching is a simple and effective film preparation technology, which is also a deformation form in some polymer processing approaches, such as thermoforming, film blowing, and extrusion 13,14 . Biaxial stretching can be used to change the structure and orientation of polymer film materials, thereby widely being studied to enhance the thermal, mechanical, dielectric, and energy storage performances of polymer materials 15–17 .…”

“…Biaxial stretching is a simple and effective film preparation technology, which is also a deformation form in some polymer processing approaches, such as thermoforming, film blowing, and extrusion. 13,14 Biaxial stretching can be used to change the structure and orientation of polymer film materials, thereby widely being studied to enhance the thermal, mechanical, dielectric, and energy storage performances of polymer materials. [15][16][17] The emergence, development, and application of novel materials and preparation methods require biaxially stretched polymer composites to possess multi-functional characteristics.…”