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. 2015 Dec 2;8(12):8279-8291.
doi: 10.3390/ma8125451.

Polypropylene/Short Glass Fibers Composites: Effects of Coupling Agents on Mechanical Properties, Thermal Behaviors, and Morphology

Jia-Horng Lin  1   2   3 , Chien-Lin Huang  4 , Chi-Fan Liu  5 , Chih-Kuang Chen  6 , Zheng-Ian Lin  7 , Ching-Wen Lou  8
Affiliations

Polypropylene/Short Glass Fibers Composites: Effects of Coupling Agents on Mechanical Properties, Thermal Behaviors, and Morphology

Jia-Horng Lin et al. Materials (Basel). .

Abstract

This study uses the melt compounding method to produce polypropylene (PP)/short glass fibers (SGF) composites. PP serves as matrix while SGF serves as reinforcement. Two coupling agents, maleic anhydride grafted polypropylene, (PP-g-MA) and maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MA) are incorporated in the PP/SGF composites during the compounding process, in order to improve the interfacial adhesion and create diverse desired properties of the composites. According to the mechanical property evaluations, increasing PP-g-MA as a coupling agent provides the composites with higher tensile, flexural, and impact properties. In contrast, increasing SEBS-g-MA as a coupling agent provides the composites with decreasing tensile and flexural strengths, but also increasing impact strength. The DSC results indicate that using either PP-g-MA or SEBS-g-MA as the coupling agent increases the crystallization temperature. However, the melting temperature of PP barely changes. The spherulitic morphology results show that PP has a smaller spherulite size when it is processed with PP-g-MA or SEBS-g-MA as the coupling agent. The SEM results indicate that SGF is evenly distributed in PP matrices, but there are distinct voids between these two materials, indicating a poor interfacial adhesion. After PP-g-MA or SEBS-g-MA is incorporated, SGF can be encapsulated by PP, and the voids between them are fewer and indistinctive. This indicates that the coupling agents can effectively improve the interfacial compatibility between PP and SGF, and as a result improves the diverse properties of PP/SGF composites.

Keywords: Short glass fibers (SGF); coupling agent; mechanical properties; polypropylene (PP); thermal behaviors.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) Tensile strength and (b) tensile modulus of PP (Polypropylene)/SGF (short glass fiber) composites.
Figure 2
Figure 2
(a) Flexural strength and (b) flexural modulus of PP/SGF composites.
Figure 3
Figure 3
Impact strength of PP/SGF composites, as related to various coupling agents.
Figure 4
Figure 4
Chemical reaction between PP-g-MA and SGF.
Figure 5
Figure 5
Chemical reaction between SEBS-g-MA and SGF.
Figure 6
Figure 6
DSC curves for (a) melting behavior and (b) crystallization behavior of PP/SGF composites.
Figure 7
Figure 7
Polarized Light Microscopy images (100×) of the PP/SGF composites that are composed of (a) 0 wt % of a coupling agent; (b) 8 wt % of PP-g-MA as a coupling agent, and (c) 8 wt % of SEBS-g-MA as a coupling agent.
Figure 8
Figure 8
Optical microscopy images (100×) of the PP/SGF composites that are composed of (a) 0 wt % of a coupling agent; (b) 8 wt % of PP-g-MA as a coupling agent; and (c) 8 wt % of SEBS-g-MA as a coupling agent.
Figure 9
Figure 9
SEM images (100×) of PP/SGF composites, which are incorporated with (a) 0 wt % of a coupling agent; (b) 2 wt %; (c) 4 wt %, (d) 6 wt %; and (e) 8 wt % of PP-g-MA; as well as (f) 2 wt %; (g) 4 wt %; (h) 6 wt %; and (i) 8 wt % of SEBS-g-MA.
Figure 10
Figure 10
SEM images (800×) of PP/SGF composites, which are incorporated with (a) 0 wt % of a coupling agent; (b) 2 wt %; (c) 4 wt %; (d) 6 wt %; and (e) 8 wt % of PP-g-MA; as well as (f) 2 wt %; (g) 4 wt %; (h) 6 wt %; and (i) 8 wt % of SEBS-g-MA.
See this image and copyright information in PMC

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