Injection-Molded Capsular Device for Oral Pulsatile Release: Development of a Novel Mold

To improve the foaming behavior of a common linear polypropylene (PP) resin, polycarbonate (PC) was blended with PP, and three different grafted polymers were used as the compatibilizers. The solid and foamed samples of the PP/PC 3:1 blend with different compatibilizers were first fabricated by melt extrusion followed by injection molding (IM) with and without a blowing agent. The mechanical properties, thermal features, morphological structure, and relative rheological characterizations of these samples were studied using a tensile test, dynamic mechanical analyzer (DMA), scanning electron microscope (SEM), and torque rheometer. It can be found from the experimental results that the influence of the compatibility between the PP and PC phases on the foaming behavior of PP/PC blends is substantial. The results suggest that PC coupling with an appropriate compatibilizer is a potential method to improve the foamability of PP resin. The comprehensive effect of PC and a suitable compatibilizer on the foamability of PP can be attributed to two possible mechanisms, i.e., the partial compatibility between phases that facilitates cell nucleation and the improved gas-melt viscosity that helps to form a fine foaming structure.

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Production and Processing of a Spherical Polybutylene Terephthalate Powder for Laser Sintering

Applied Sciences ◽

10.3390/app9071308 ◽

2019 ◽

Vol 9 (7) ◽

pp. 1308 ◽

Cited By ~ 11

Author(s):

Rob Kleijnen ◽

Manfred Schmid ◽

Konrad Wegener

Keyword(s):

Mechanical Properties ◽

Thermal Processing ◽

Selective Laser Sintering ◽

Spherical Shape ◽

Laser Sintering ◽

Polybutylene Terephthalate ◽

Powder Production ◽

Injection Molded ◽

Continuous Extrusion ◽

Matrix Powder

This work describes the production of a spherical polybutylene terephthalate (PBT) powder and its processing with selective laser sintering (SLS). The powder was produced via melt emulsification, a continuous extrusion-based process. PBT was melt blended with polyethylene glycol (PEG), creating an emulsion of spherical PBT droplets in a PEG matrix. Powder could be extracted after dissolving the PEG matrix phase in water. The extrusion settings were adjusted to optimize the size and yield of PBT particles. After classification, 79 vol. % of particles fell within a range of 10–100 µm. Owing to its spherical shape, the powder exhibited excellent flowability and packing properties. After powder production, the width of the thermal processing (sintering) window was reduced by 7.6 °C. Processing of the powder on a laser sintering machine was only possible with difficulties. The parts exhibited mechanical properties inferior to injection-molded specimens. The main reason lied in the PBT being prone to thermal degradation and hydrolysis during the powder production process. Melt emulsification in general is a process well suited to produce a large variety of SLS powders with exceptional flowability.

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Design of Shape Memory Thermoplastic Material Systems for FDM-Type Additive Manufacturing

Materials ◽

10.3390/ma14154254 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4254

Author(s):

Paulina A. Quiñonez ◽

Leticia Ugarte-Sanchez ◽

Diego Bermudez ◽

Paulina Chinolla ◽

Rhyan Dueck ◽

...

Keyword(s):

Additive Manufacturing ◽

Shape Memory ◽

Thermomechanical Processing ◽

Material Selection ◽

Shape Memory Polymer ◽

Fused Filament Fabrication ◽

Materials Development ◽

Thermoplastic Material ◽

Polymer Systems ◽

Injection Molded

The work presented here describes a paradigm for the design of materials for additive manufacturing platforms based on taking advantage of unique physical properties imparted upon the material by the fabrication process. We sought to further investigate past work with binary shape memory polymer blends, which indicated that phase texturization caused by the fused filament fabrication (FFF) process enhanced shape memory properties. In this work, two multi-constituent shape memory polymer systems were developed where the miscibility parameter was the guide in material selection. A comparison with injection molded specimens was also carried out to further investigate the ability of the FFF process to enable enhanced shape memory characteristics as compared to other manufacturing methods. It was found that blend combinations with more closely matching miscibility parameters were more apt at yielding reliable shape memory polymer systems. However, when miscibility parameters differed, a pathway towards the creation of shape memory polymer systems capable of maintaining more than one temporary shape at a time was potentially realized. Additional aspects related to impact modifying of rigid thermoplastics as well as thermomechanical processing on induced crystallinity are also explored. Overall, this work serves as another example in the advancement of additive manufacturing via materials development.

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