EFFECT OF MOLECULAR WEIGHT AND LITERATURE REVIEW OF 3D PRINTING
By: Narrations Review.G Mathew
Tags: 3D Printing, Polymer, Literature Review

EFFECT OF MOLECULAR WEIGHT AND LITERATURE REVIEW OF 3D PRINTING

Introduction

3D printing (sometimes referred to as rapid prototyping (RP) or additive manufacturing AM or solid free-forming (SFF)) is used to manufacture 3D solid objects by fusing layers or depositing materials like polymers, metals, powdered substances, liquids, or biological living cells. in layers to produce a 3D object. Producing a digital model is the first step in additive manufacturing. Computer-aided design (CAD) software is used to create a meshed 3D digital model. A surface tessellation language (STL) is commonly created. 2D files are further made by slicing the data of the 3D structure. The coordinates of the virtual object and the two-dimensional structure are then used to steer the motor, which further positions the orifice. Production of customized parts from metals, ceramics, and polymers can be carried out.

Materials suited for 3D printing

Thermoplastic polymer materials such as acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), polyamide (PA), polycarbonate (PC). Thermosetting polymers such as epoxy resins could also be processed. In order to complete the polymerization process, epoxy resins are required to undergo UV assisted or thermal curing as the material is quite reactive and to increase the viscosity.

Fused Deposition Modelling or Fused Filament Fabrication

During fabrication, the material passes through the heating element that partially melts the filament. It is fed through the nozzle. The material extruding through the nozzle is kept at a temperature above the melting point with the help of resistive heaters for the ease of flow. The nozzle moves in the X-Y direction and it deposits a layer of material. In the X-Y plane, a 0.001-inch resolution is achievable. After finishing the layer, the platform holding the material moves in the Z direction to begin depositing the new layer on the top of the previous layer. Both layers get fused together.

How do polymers diffuse

Parts produced from FDM suffers poor interfacial adhesion between layers. And it is due to poor diffusion of slow and very large polymer across the inter filament interface. It is already known that smaller polymer diffuses more quickly than the larger counterparts. Entropically it is favorable that the smaller polymer chains migrate the interface preferentially. By utilizing the thermodynamic principle and chemistry, bimodal blends can be prepared by incorporating smaller but identical polymers to the neat filament. Under the same printing condition and the lower molecular weight (LMW) polymer chains readily diffuse across the surface and hence it improves the entanglement.

Another method which improves adhesion between layers is chemical crosslinking. Crosslinking involves the formation of either noncovalent or covalent bonds between polymer chains. A variety of experiments have investigated the formation of noncovalent bonds in polymer systems, including ionic crosslinks in carboxylated-nitrile rubber (XNBR) and hydrogen bonding in the supramolecular network of maleated polyethylene-octene elastomer.