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A composite of 70/30 poly(lactic acid)/hydroxyapatite was systematically prepared using various amounts of glycidyl methacrylate as reactive compatibilizer or Joncryl ADR®-4368 containing nine glycidyl methacrylate functions as a chain extension/branching agent to improve the mechanical and biological properties for suitable usage as internal bone fixation devices. The effect of glycidyl methacrylate/Joncryl on mechanical properties of poly(lactic acid)/hydroxyapatite was investigated through flexural strength. Cell proliferation and differentiation of osteoblast-like MC3T3-E1 cells cultured on the composite samples were determined by Alamar Blue assay and alkaline phosphatase expression, respectively. Result shows that flexural strength tends to decrease, as glycidyl methacrylate content increases except for 1 wt.% glycidyl methacrylate. With an addition of dicumyl peroxide, the flexural strength shows an improvement than that of without dicumyl peroxide probably due to the chemical bonding of the hydroxyapatite and poly(lactic acid) as revealed by FTIR and NMR, whereas the composite with 5 wt.% Joncryl shows the best result, as the flexural strength increases getting close to pure poly(lactic acid). The significant morphology change could be seen in composite with Joncryl where the uniform agglomeration of hydroxyapatite particles oriented in poly(lactic acid) matrix. Addition of the epoxy functional compatibilizers at suitable percentages could also have benefits to cellular attachment, proliferation, differentiation and mineralization. So that, this poly(lactic acid)/hydroxyapatite composite could be a promising material to be used as internal bone fixation devices such as screws, pins and plates.

Single-purpose greenhouse films such as UV-blocking, NIR-blocking, or ultrathermic films are commonly developed in various climate regions. However, multifunctional films of combined functions are rarely explored, especially in the tropical regions. In this research, a multifunctional film having high UV filtration, high NIR reflection, and good light diffusion was developed for a greenhouse cover application in tropical regions. Effects of type, quantity, and particle size of additives on optical properties (280–2500 nm) and mechanical properties of 3-layer laminated films comprising 90% LLDPE/10% EVA polymer matrix and additives were studied. Results show that properties of those films are adjustable by varying types, particle size, and content of additives. The UV transmission of the film was ranged from 13.7 to 32.7 %T, NIR reflection from 12.1 to 19.8 %R, and %haze diffusion from 39.5 to 72.3 where photosynthetically active radiation (PAR) transmission was in the range of 62.6–78.9 %T. Those films exhibit tensile strength of 18–24 MPa, modulus of elasticity of 200–280 MPa, and elongation at break of 610–810%. A field test of the newly developed films as a cover for a greenhouse of 6 m wide ×24 m long ×4.3 m high with double roof design showed a better quality of plant growth in terms of weight, height, and bush width compared to a 7% UV absorber commercial film.

Nanofibers of poly(L‐lactide‐co‐DL‐Lactide) (PDLLAx) copolymers with DL‐lactate (DLLA) contents of 0, 2.5, 7.5, and 50%, which exhibit strong structure/properties correlation, were fabricated by electrospinning. Effect of the copolymer structure and electrospinning conditions on morphology and properties of the fibers were examined by SEM, DSC, XRD, and tensile measurements. Bead‐free fibers of PDLLAx prepared from a DMF/CHCl3 mixed solvent are roughly 10‐times smaller in size (600–800 nm), with lower degree of surface porosity, compared to those of CHCl3. When CHCl3 is employed, an increase in size (2.4–5.5 μm) and surface porosity (0–45%) with relative humidity value is observed in crystallizable copolymers, whereas an amorphous copolymer shows a reverse trend. Thermal properties and chain arrangements of the electrospun fibers are critically affected by DLLA content of the copolymers and electrospinning conditions, as a result from interplay between intermolecular and intramolecular hydrogen bonding. Contents of crystalline domains and “physical crosslinks” generated from DL lactate segments are proposed as the origin of this phenomenon. Fiber mats of PDLLA with 50% DLLA content show a large improvement in all aspects of mechanical properties, which are suitable for various biomedical applications. POLYM. ENG. SCI., 54:472–480, 2014. © 2013 Society of Plastics Engineers

Hollow polymeric nanoparticles have attracted vast attention as UV-shielding materials in personal care products due to their excellent light scattering characteristics and low density. In this work, a process for fabricating biocompatible/degradable poly­(lactic acid-co-glycidyl methacrylate), P­(LA-co-GMA), hollow nanoparticles via one-step phase inversion emulsification is examined, to gain insights into their formation mechanisms and optimization of the process parameters. The migration of poly­(vinyl alcohol) (PVA) (stabilizing agent) from the oil droplet to the oil/water interface while entangled with cross-linked P­(LA-co-GMA) chains and the fast evaporation rate of the chloroform solvent play an essential role in the hollow structure formation. Under optimum conditions, monodispersed hollow nanoparticles, with an average size of 500–700 nm and good colloidal stability, are obtained. The as-prepared hollow nanoparticles exhibit high UV shielding capabilities and low toxicity. The nanoparticles show high stability under UV exposure but can be completely degraded within 24 weeks under accelerated hydrolysis conditions. The materials have a high potential for use as environmental-friendly UV-shielding additives in cosmetic applications.

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